Messerschmitt Me P.1101

[T. A. Gardner]

Of note here is that while the Messerschmitt P 1101 never flew, the prototype was delivered to Bell Aircraft in the US following the war where it was closely copied--with some improvements like being able to change the wing sweep in flight-- as the Bell X-5. So, we have some idea of how the Messerschmitt design would have performed in flight.
The Bell X-5 was considered somewhat dangerous to fly and had very vicious spin and stall characteristics (sort of like the P-39 maybe?). Both aircraft were really too small to be fitted with a useful armament or fire control systems. The Bell design did have some use in furthering both swept wing performance as well as in development of variable wing position aircraft. The Bell design was however much better than the competing Navy Grumman XF10F Jaguar that was a veritable death trap to fly.

Would the production version of the P.1101, which was intended to have been just a bit larger, have been better for housing armament and other systems?

Based on what we know of the very similar Bell X-5, I'd postulate that the P1101 would have had a protracted development due to the stability and spin issues it would almost certainly exhibit. I think the aircraft would have seen say about a half-dozen or so prototypes built that tried to rectify the issues over roughly 18 to 24 months then get dropped as the state of the art had moved beyond it.
Bell and the USAF floated, for a short time, the idea of production of the X-5 as a lightweight, low cost fighter but dropped the idea because of the plane's vicious tendencies in flight.

That being said, would you say, compared to the Focke-Wulf Ta-183, the Messerschmitt Me P.1101 does not have the same realized potential in the time required for it to be useful before being passed over? I recall such and such a South American country working with Kurt Tank post-war to develop a better-engineered version of the Ta-183 and that it flew rather well. Correct me here if I am wrong of course. Just food for discussion.

The Focke Wulf design had more potential to work. Postwar, Kurt Tank designed and produced what was pretty much a slightly better variant of the Ta 183 in Argentina, the FMA IAe 33 Pulqui II. While only four prototypes were produced, these were flown enough to find the aircraft was generally workable except at the upper edges of its performance envelope. At the upper end of performance, the plane exhibited instability, and serious stall issues. While Tank and other engineers on the project worked to rectify these issues they were never eliminated before the project ended. I would note, that these sorts of problems cropped up a lot with every design in the late 1940's so it isn't all just poor engineering, but also a lack of knowledge of high subsonic and transonic flight regimes.
A combination of financial and political instability coupled with lack of a sufficiently large, skilled workforce to build the planes in Argentina doomed the project.

 

[T. A. Gardner]

In the Messerschmitt construction description of November 2, 1944, the P 1101 is offered as a single-seat 'Wilde Sau' night fighter (see attached). There's no known mention of it as a night fighter after this.

If what Messerschmitt was proposing was a "Wilde Sau" type nightfighter, I'd say it wouldn't be worth the trouble. The loss rate on Wilde Sau single seat fighters per sortie was over 80%. While it was possible for a highly skilled pilot to make these tactics work, for the average pilot flying a single seat fighter plane at night was a virtual death sentence, and mostly to operational accident rather than enemy action. It was just too easy for a pilot to become disoriented, lost, or crash on attempting to land for them to fly this sort of plane at night in combat.

 

[Justo Miranda]

O boy, Lepage is an extremely unreliable author, I wouldn't even bother with his publications... He is actually a draftsman, who just adds some text (based on any information he had on hand) to his comic style drawings, which are not accurate or wrongly captioned too, and creates books this way. His works on the Flak and Hitlerjugend are unbelievably poor, full of the most fundamental mistakes. And, for example, in his Flak book he posts a thank you note fore a person, who provided him with technical information - it clearly means, he started his work knowing nothing on the subject.

Interesting. Thank you for that. I figured most of the jet aircraft he listed were dubious given that a few were traceable to Luft 46 and others being entirely napkin drawings so to speak. That being said, despite the likely dubious origin of this concept, would you say that compared to the "stag antlers" of FuG 202, 212, 218, etc., that FuG 240 would be more appropriate for such an aircraft in a night fighter role had the Germans actually committed to developing it? I do like the concept but I feel like it would be unrealistic when considering that production of said aircraft would then deviate between two separate designs, amounting to more work than is necessary, rather than just slapping on a dipole array.

It is highly unlikely that the P 1101 or a derivative thereof would be suitable as a nightfighter. In the late 40's and into the early 50's the state of the art in nightfighter technology required a dedicated radar operator aboard the plane. It wouldn't be until such systems as the Hughes E series of semi-automatic intercept computers were developed that you could successfully do all-weather intercepts with just one crew member. Germany during the war did put radar on single seat fighters, but these didn't produce much in the way of exceptional results.

Consider one of the first single-seat all-weather fighters, the F-86D. The "Dogship" as it became known fits this bill. It had the Hughes E-4 using an APG 36 radar to perform intercepts. It was at once a technological marvel and maintenance nightmare. Germany was nowhere close to producing anything remotely that sophisticated in 1945.

Some single engine fighters of the types Messerschmitt Bf 109 G-6 and Focke-Wulf Fw 190 A-6 used in operations Helle Nachtjadg and Wilde Sau from the summer of 1943 were fast enough to hunt the RAF Mosquitos, but lacked the electronic equipment Himmelbetteinsatz necessary to locate them in the dark. In February 1944, some Bf 109 G-6/U4N, equipped with passive radar receivers FuG 350 Naxos Z, began to operate at night with the 1./ NJG 10. This equipment was designed to detect the emissions of cartographic radar H2S used by the British four engine bombers, but not those used by the Mosquito.

The NJG 11 was formed as a night fighter squadron specialized in the experimentation with radars. In the summer of 1944, a Fw 190 A-6 / R6 was equipped with a FuG 217 L Neptun Liliput radar using it as a rangefinder for launching rockets W.Gr.21. Flying tests were also carried out with a Fw 190 A-8/R11 equipped with a FuG 217/218 Neptun J3 radar capable of measuring the azimuth and with Hirschgeweih antennas on the wings but it was found out that the drag generated by them caused an unacceptable loss of speed. The conclusion was that the most suitable model for night combat was the Fw 190 A-6 / R11. It was equipped with a FuG 217 Neptun J1 radar of inferior performances to those of the J3, but its Letzler aerials generated less drag than the Hirschgeweih of the most advanced model.

In early 1944, the Fw 190 A-6 / R11 began to be used by the night fighter units JG 300, JG 302, 2./NJGr 10, 1./NJG 10 and NJG 101 with few results because its BMW 801 engine lost power over 6,000 m of altitude. It was also useless to intercept the Oboe Mosquitos flying at 9,000 m. Additionally, its armament lacked the punch required to demolish a Lancaster in a single attack. The Messerschmitt Bf 109 G Series 5 and 6 had the right speed and ceiling to deal with the Mosquito, but their use in night operations was problematic given the fragility of their landing gear and the absence of blind-landing equipment.

However, in the summer of 1943 tests were carried out on two Bf 109 G-6 / N equipped with prototypes of the FuG 217 and Letzler aerials radar. The operational version, called the Bf 109 G-5/AS, with pressurized cockpit and DB 605 AS engine, was used in mid-1944 by the II./NJG 11 at high-altitude interceptions. Combat experience showed that single seat fighters were not suitable for night combat. In addition to the problems experienced with its landing gear, short range and aerials and the absence of blind landing devices, it was discovered that the glare of radarscope ruined the night vision of the pilot, who also needed to keep an eye on the airspace around him. For this reason, an aircraft of the II./JG 300 rammed a Lancaster in March 1944.

What they needed was a fast aircraft, with an extended range and a second crewmember to take care of the radar. After discarding the options represented by the Arado Ar 240 C-2 and the Messerschmitt Me 410 C/N, the Luftwaffe thought to find the solution in the Focke-Wulf Ta 154, a machine specially designed as night fighter, that used a wood construction system like that of its British adversary. Unfortunately for the Germans, during the first flying trials carried out with the prototype V2 in September 1943, it was verified that the drag generated by the Matratzen aerials of the radar FuG 212 reduced the maximum speed by 12 per cent. Similar results were obtained in December with the Hirschgeweih aerials of the FuG 220 installed in the prototype V3

It was expected that the Letzler aerials installed in the operational version Ta 154 A-4 would improve the performances, but after several accidents it was discovered that this model suffered a structural defect impossible to correct and the Luftwaffe rejected its use in nocturnal operations on 7 November 1944.

The Heinkel He 219 was not considered a good option; its performances were inferior to those of the Ta 154 due to the excessive weight of the first-generation ejector seats, activated by compressed air, and the Hirschgeweih aerials of the radar Lichtenstein SN-2 that generated even more drag than those of the Neptun J3.

In 25 October 1944, the OKL ordered the conversion of the fastest available airplanes -Me 262, Ar 234 and Do 335 - into emergency night fighters, following the Sofortprogramm directive. The modification consisted of installing a Neptun radar and a second crew member to operate it. The Me 262 B-1a/U1 and the Ar 234 B-2N, that were thus transformed, could enter service with some success in 1945. However, the air drag generated by the big Hirschgeweih antennae, installed in the nose, and the removal of one of the fuel tanks, to make room for the radar operator, penalised the maximum speed and endurance and partially overrode the advantage of the initial design.

The Sofortprogramm did not solve the problem

On 27 January 1945, the OKL published the Vorrückenprogramm for high performance night fighters, equipped with the new radar Telefunken FuG 222 Pauke S with parabolic antenna of 45 cm of diameter. It was installed INTERNALLY, within an aerodynamic container of di-electric material placed in the nose of the airplane. In this model, the scope was replaced by a Revi device equipped with a red filter that did not affect the night vision of the pilot. It was expected that the new night fighter would reach a maximum speed of 900 kph, with a service ceiling of 9,000 m and have an armament of four forward-firing MK 108/30 cannons.

By the end of 1944 the Heinkel engineers designed an advanced system of automatic triggering weapons combining the fire control radar FuG 222 Pauke S with the gyroscopic gunsight Askania EZ 42 Adler. The 1078 project was created to prove that the system could be integrated in single engine fighters, providing them with additional capacity to act as night fighter or Moskitojäger controlled by the ground command by means of the FuG 25a and FuG 125a devices installed inboard.

In February, 1945 the OKL added the requirement that the new fighter should include the FuG 244 radar which, together with the Schräge Musik guns and its ammunition, added 300 kg to the weight of the airplane.

The wind tunnel test on the Messerschmitt P.1101 models, performed by the AVA-Göttingen institute during the autumn of 1944, revealed that the maximum speed would still be lower than their expectations.

The reason was the turbulence generated in the joint of the rear fuselage and the engine nacelle, that had an '8' shaped section. It was discovered that the airframe generated a triple shock wave at transonic speed. The first one was formed around the cockpit hood, the second over the wing and the third one over the tail plane. The shock waves overlapped among each other with a braking effect similar to an arrow going through three disks of felt launched in the air.

The Messerschmitt designers tried to solve the problem replacing the cockpit hood with another with low drag type Rennkabine, originally designed for a high-speed version of the Me 262. Wind tunnel test performed with a 'V' ant 'T' shaped tail planes revealed that such modifications did not substantially improve aerodynamic performance and the P.1101 Jägernotprogramm was cancelled at the end of 1944.

Possibly the manufacturer considers the modification of the P.1101 as a night fighter but, by the beginning of 1945, the Luftwaffe did not need an all-weather interceptor moskitojäger, but a heavy night fighter with extended range and a great amount of electronic equipment.

On 27 February, the Technisches Amt published the Hochleistung Nachtjäger specification for a high-performance night fighter. It called for an advanced airplane, powered by two HeS 011 A turbojets, using the new search radar Telefunken FuG 244 Bremen 0, that had a parabolic mirror of 70 cm diameter and additional Schräge Musik weapons.

On 2 March 1945, the OKL requested the inclusion of a third crew member and the addition of a tail warning radar device Siemens/FFO FuG 218 Neptun R3 with Yagi aerial. This left the Junkers, Heinkel and Horten designs out of the contest, as they could not increase the crew area for structural reasons.

 

[Sherman Tank]

In the Messerschmitt construction description of November 2, 1944, the P 1101 is offered as a single-seat 'Wilde Sau' night fighter (see attached). There's no known mention of it as a night fighter after this.

If what Messerschmitt was proposing was a "Wilde Sau" type nightfighter, I'd say it wouldn't be worth the trouble.

Since when did something being objectively not worth the trouble ever stop Nazi Germany?

 

[Airborne2001]

The Messerschmitt designers tried to solve the problem replacing the cockpit hood with another with low drag type Rennkabine, originally designed for a high-speed version of the Me 262. Wind tunnel test performed with a 'V' ant 'T' shaped tail planes revealed that such modifications did not substantially improve aerodynamic performance and the P.1101 Jägernotprogramm was cancelled at the end of 1944.

So would the T-tail modification of the aircraft not be enough to improve the spin issues? (I am not that well versed in this topic, so I apologize if this question sounds a bit weird.)

Spoiler: (Swastika Warning)

 

[Basil]

Of note here is that while the Messerschmitt P 1101 never flew, the prototype was delivered to Bell Aircraft in the US following the war where it was closely copied--with some improvements like being able to change the wing sweep in flight-- as the Bell X-5. So, we have some idea of how the Messerschmitt design would have performed in flight.
The Bell X-5 was considered somewhat dangerous to fly and had very vicious spin and stall characteristics (sort of like the P-39 maybe?). Both aircraft were really too small to be fitted with a useful armament or fire control systems. The Bell design did have some use in furthering both swept wing performance as well as in development of variable wing position aircraft. The Bell design was however much better than the competing Navy Grumman XF10F Jaguar that was a veritable death trap to fly.

Would the production version of the P.1101, which was intended to have been just a bit larger, have been better for housing armament and other systems?

Interesting question - was the production version of the P 1101 intended to have been just a bit larger?
The original planned experimental version of the P 1101 was set out in drawing XVIII/138 of November 8, 1944. It shows an aircraft 8.815m long with a wingspan of 8.08m.
The original planned series version of the P 1101 was set out in drawing XVIII/130 of November 1, 1944. It was 8.915m long, also with a wingspan of 8.08m.
So, circa November 1944, the series version was 10cm longer - not really a massive amount of additional space for housing armament and other systems.
By the end of February 1945, while the experimental version of the design had remained fixed, the series version had been significantly altered. The data presented to the project comparison meeting at that point gives a wingspan of 8.25m but no fuselage length is offered. However, using the drawing included in the meeting documents, and the 8.25m span (the numbers on the best known copy of the drawing are too blurry to read), it is possible to determine that the fuselage length was about 8.94m.
It would seem that the series production version of the P 1101 was intended to be just a bit larger than the experimental version - but only to the tune of 40mm additional wingspan and 125mm in length. Probably not enough to make much difference, load-wise.

Was the P 1101 considered as a night fighter? Yes it was. The second known version, shown in drawing XVIII/113 of August 30, 1944, shows a design that was intended to be optionally extendable by adding a 650mm fuselage section - turning it into a two seater. Presumably this is is what LePage was basing his drawing on (though his drawing only bears a passing resemblance to the actual design). This design, with this feature, was discussed at a comparison meeting on September 10, 1944, and it wasn't actually made explicit that the extra seat was for a radar operator (there's no mention of installing radar equipment or night-fighting at the meeting) - it may only have been intended to make the aircraft suitable for conversion to a trainer.
In the Messerschmitt construction description of November 2, 1944, the P 1101 is offered as a single-seat 'Wilde Sau' night fighter (see attached). There's no known mention of it as a night fighter after this.

View attachment 651919

Interesting to see that the Schönwetterjäger would also have a Fug 218 radar. I assume this was for automatic ranging feeding the EZ 42.

 

[Justo Miranda]

The Messerschmitt designers tried to solve the problem replacing the cockpit hood with another with low drag type Rennkabine, originally designed for a high-speed version of the Me 262. Wind tunnel test performed with a 'V' ant 'T' shaped tail planes revealed that such modifications did not substantially improve aerodynamic performance and the P.1101 Jägernotprogramm was cancelled at the end of 1944.

So would the T-tail modification of the aircraft not be enough to improve the spin issues? (I am not that well versed in this topic, so I apologize if this question sounds a bit weird.)

Spoiler: (Swastika Warning)

View attachment 651964

T-tailplane, a too radical configuration that was object of criticism by the Technisches Amt. Its main objection was based on the danger posed by the tailplane to a pilot attempting to bail out at high speed. The ejector seat designed in 1942, to equip future versions of the Fw 190, could launch the pilot at a height of 2 m above the cockpit floor, with a margin of 43 cm over the tailfin. But the T-tailplane, designed to avoid the turbulent airflow generated by the cockpit hood, had to be installed more than three meters high above the level of the cockpit floor to be effective.

The Technisches Amt calculated that during an ejection at critical Mach number, the T-tailplane would reach the pilot in only 0.018 seconds. In 1944, the most effective ejector seat of the world was the Heinkel Kartusche propelled by an explosive cartridge with 30 grams of powder, with an ejection speed of 11 m/sec and 12 g. It was designed for speeds not exceeding 700 kph. At 1,000 kph and using a T-tailplane it was necessary to increase the ejection speed to 200 g, with equally lethal effects for the pilot.

 

[newsdeskdan]

Of note here is that while the Messerschmitt P 1101 never flew, the prototype was delivered to Bell Aircraft in the US following the war where it was closely copied--with some improvements like being able to change the wing sweep in flight-- as the Bell X-5. So, we have some idea of how the Messerschmitt design would have performed in flight.
The Bell X-5 was considered somewhat dangerous to fly and had very vicious spin and stall characteristics (sort of like the P-39 maybe?). Both aircraft were really too small to be fitted with a useful armament or fire control systems. The Bell design did have some use in furthering both swept wing performance as well as in development of variable wing position aircraft. The Bell design was however much better than the competing Navy Grumman XF10F Jaguar that was a veritable death trap to fly.

Would the production version of the P.1101, which was intended to have been just a bit larger, have been better for housing armament and other systems?

Based on what we know of the very similar Bell X-5, I'd postulate that the P1101 would have had a protracted development due to the stability and spin issues it would almost certainly exhibit. I think the aircraft would have seen say about a half-dozen or so prototypes built that tried to rectify the issues over roughly 18 to 24 months then get dropped as the state of the art had moved beyond it.
Bell and the USAF floated, for a short time, the idea of production of the X-5 as a lightweight, low cost fighter but dropped the idea because of the plane's vicious tendencies in flight.

That being said, would you say, compared to the Focke-Wulf Ta-183, the Messerschmitt Me P.1101 does not have the same realized potential in the time required for it to be useful before being passed over? I recall such and such a South American country working with Kurt Tank post-war to develop a better-engineered version of the Ta-183 and that it flew rather well. Correct me here if I am wrong of course. Just food for discussion.

The Focke Wulf design had more potential to work. Postwar, Kurt Tank designed and produced what was pretty much a slightly better variant of the Ta 183 in Argentina, the FMA IAe 33 Pulqui II. While only four prototypes were produced, these were flown enough to find the aircraft was generally workable except at the upper edges of its performance envelope. At the upper end of performance, the plane exhibited instability, and serious stall issues. While Tank and other engineers on the project worked to rectify these issues they were never eliminated before the project ended. I would note, that these sorts of problems cropped up a lot with every design in the late 1940's so it isn't all just poor engineering, but also a lack of knowledge of high subsonic and transonic flight regimes.
A combination of financial and political instability coupled with lack of a sufficiently large, skilled workforce to build the planes in Argentina doomed the project.

Although Tank reportedly took the Ta 183 plans to Argentina, I think the Pulqui II was physically a very different aircraft.

 

[newsdeskdan]

The Heinkel He 219 was not considered a good option; its performances were inferior to those of the Ta 154 due to the excessive weight of the first-generation ejector seats, activated by compressed air, and the Hirschgeweih aerials of the radar Lichtenstein SN-2 that generated even more drag than those of the Neptun J3.

In 25 October 1944, the OKL ordered the conversion of the fastest available airplanes -Me 262, Ar 234 and Do 335 - into emergency night fighters, following the Sofortprogramm directive. The modification consisted of installing a Neptun radar and a second crew member to operate it. The Me 262 B-1a/U1 and the Ar 234 B-2N, that were thus transformed, could enter service with some success in 1945. However, the air drag generated by the big Hirschgeweih antennae, installed in the nose, and the removal of one of the fuel tanks, to make room for the radar operator, penalised the maximum speed and endurance and partially overrode the advantage of the initial design.

The Sofortprogramm did not solve the problem

On 27 January 1945, the OKL published the Vorrückenprogramm for high performance night fighters, equipped with the new radar Telefunken FuG 222 Pauke S with parabolic antenna of 45 cm of diameter. It was installed INTERNALLY, within an aerodynamic container of di-electric material placed in the nose of the airplane. In this model, the scope was replaced by a Revi device equipped with a red filter that did not affect the night vision of the pilot. It was expected that the new night fighter would reach a maximum speed of 900 kph, with a service ceiling of 9,000 m and have an armament of four forward-firing MK 108/30 cannons.

By the end of 1944 the Heinkel engineers designed an advanced system of automatic triggering weapons combining the fire control radar FuG 222 Pauke S with the gyroscopic gunsight Askania EZ 42 Adler. The 1078 project was created to prove that the system could be integrated in single engine fighters, providing them with additional capacity to act as night fighter or Moskitojäger controlled by the ground command by means of the FuG 25a and FuG 125a devices installed inboard.

In February, 1945 the OKL added the requirement that the new fighter should include the FuG 244 radar which, together with the Schräge Musik guns and its ammunition, added 300 kg to the weight of the airplane.

The wind tunnel test on the Messerschmitt P.1101 models, performed by the AVA-Göttingen institute during the autumn of 1944, revealed that the maximum speed would still be lower than their expectations.

The reason was the turbulence generated in the joint of the rear fuselage and the engine nacelle, that had an '8' shaped section. It was discovered that the airframe generated a triple shock wave at transonic speed. The first one was formed around the cockpit hood, the second over the wing and the third one over the tail plane. The shock waves overlapped among each other with a braking effect similar to an arrow going through three disks of felt launched in the air.

The Messerschmitt designers tried to solve the problem replacing the cockpit hood with another with low drag type Rennkabine, originally designed for a high-speed version of the Me 262. Wind tunnel test performed with a 'V' ant 'T' shaped tail planes revealed that such modifications did not substantially improve aerodynamic performance and the P.1101 Jägernotprogramm was cancelled at the end of 1944.

Possibly the manufacturer considers the modification of the P.1101 as a night fighter but, by the beginning of 1945, the Luftwaffe did not need an all-weather interceptor moskitojäger, but a heavy night fighter with extended range and a great amount of electronic equipment.

On 27 February, the Technisches Amt published the Hochleistung Nachtjäger specification for a high-performance night fighter. It called for an advanced airplane, powered by two HeS 011 A turbojets, using the new search radar Telefunken FuG 244 Bremen 0, that had a parabolic mirror of 70 cm diameter and additional Schräge Musik weapons.

On 2 March 1945, the OKL requested the inclusion of a third crew member and the addition of a tail warning radar device Siemens/FFO FuG 218 Neptun R3 with Yagi aerial. This left the Junkers, Heinkel and Horten designs out of the contest, as they could not increase the crew area for structural reasons.

There's a lot wrong with this.
The He 219 was not considered a good option because it required too much aluminium to build, there weren't enough jigs in existence to build it in large quantities and the easily mass-produced Ju 88 G could do basically the same job for far less cost.
Efforts to turn the Ar 234 into a night fighter started in December 1943 and the company was formally commissioned to create a night fighter based on the Ar 234 B-1 shortly after September 12, 1944.
Efforts to turn the Me 262 into a night fighter started in July 1944. The company was formally commissioned to develop a two-seater night-fighter based on the Me 262 B1 on September 1, 1944.
I've never seen any mention of a 'Sofortprogramm' in contemporary documents. And I have seen a LOT of contemporary documents on German WW2 night fighter projects (nor a Vorrueckenprogramm, nor a Jaegernotprogramm. Similarly, Schraege Musik is never used in contemporary documents).
A specification for a new 3-seater night fighter was issued on August 28, 1944, to Blohm & Voss, Dornier, Focke-Wulf, Heinkel and Messerschmitt. Initial engine options were Jumo 222 E/F, As 413, DB 603 L or DB 613. Combination piston/turbojet was to be tested.
The full story of late-war German night fighter development is one of continually shifting requirements as personnel and organisational structures rapidly changed. New specifications were issued on January 27, February 27 and April 2. I have copies of all of them and none of them mention the FuG 222 Pauke S - but all require a crew of 3 and FuG 218 R. Horten and Junkers were never involved in the night fighter design competition, though Horten did apparently want their 229 to be considered (it wasn't).
Heinkel's wartime P 1078 was the company's entry for the 1-TL-Jaeger competition, after the company was banned from offering anything based on the He 162, and was not concerned with the integration of fire control systems. These only appear in the postwar P 1078 drawings which, if they were drafted during the war, do not appear to have been submitted for formal consideration.
Goettingen's wind tunnel tests on various P 1101 configurations (including a T-tail or 'hochgelegte Hoehenleitwerke') appear to have begun on November 15, 1944, and continued on into February 1945, with the results finally being reported on by Messerschmitt on March 1, 1945.

 

[iverson]

So would the T-tail modification of the aircraft not be enough to improve the spin issues? (I am not that well versed in this topic, so I apologize if this question sounds a bit weird.)

As I understand it, T-tails create stability issues of their own on aircraft with swept, tapered wings. When a swept wing stalls, the center of lift moves forward, pitching the aircraft up. Under these conditions, turbulent air from the wing blankets a high-mounted tail--especially a T-tail--and reduces or eliminates the latter's control power. The stall characteristics of highly tapered wings like the P.1101's magnify the effect. As a result, tail planes have been placed low on the tail plane or fuselage on most successful high-performance aircraft since.

So, if anything, I'd expect a T-tail to exacerbate the overall handling characteristics.

 

[sienar]

Of note here is that while the Messerschmitt P 1101 never flew, the prototype was delivered to Bell Aircraft in the US following the war where it was closely copied--with some improvements like being able to change the wing sweep in flight-- as the Bell X-5. So, we have some idea of how the Messerschmitt design would have performed in flight.
The Bell X-5 was considered somewhat dangerous to fly and had very vicious spin and stall characteristics (sort of like the P-39 maybe?). Both aircraft were really too small to be fitted with a useful armament or fire control systems. The Bell design did have some use in furthering both swept wing performance as well as in development of variable wing position aircraft. The Bell design was however much better than the competing Navy Grumman XF10F Jaguar that was a veritable death trap to fly.

Bell was very much enamored with the design and they certainly copied the overall layout, but to call it a copy is just going too far. Structurally it is quite different, with the wings sweeping and translating simultaneously (which makes it what, one of two/three aircraft to every do this?). There are also numerous other aerodynamic and structural differences, some rather substantial.

Additionally you should be careful about trying to deduce flight characteristics from looking at thee-views. The P-1101 has fairly reasonable tail volume coefficients, ~0.47 horizontal and ~0.07 vertical. Voigt designed the wing to have a larger LE radius near the tip and the slats were extended after testing to alleviate tip stall. Would the aircraft have benign handling by todays standards? Of course not. Would it have been a deal breaker for that time? Or even that bad as far as first/second gen jets are concerned? That is much harder to say. Especially when the v1 was being built to test the wing at different sweeps, with

Of note here is that while the Messerschmitt P 1101 never flew, the prototype was delivered to Bell Aircraft in the US following the war where it was closely copied--with some improvements like being able to change the wing sweep in flight-- as the Bell X-5. So, we have some idea of how the Messerschmitt design would have performed in flight.
The Bell X-5 was considered somewhat dangerous to fly and had very vicious spin and stall characteristics (sort of like the P-39 maybe?). Both aircraft were really too small to be fitted with a useful armament or fire control systems. The Bell design did have some use in furthering both swept wing performance as well as in development of variable wing position aircraft. The Bell design was however much better than the competing Navy Grumman XF10F Jaguar that was a veritable death trap to fly.

Would the production version of the P.1101, which was intended to have been just a bit larger, have been better for housing armament and other systems?

Based on what we know of the very similar Bell X-5, I'd postulate that the P1101 would have had a protracted development due to the stability and spin issues it would almost certainly exhibit. I think the aircraft would have seen say about a half-dozen or so prototypes built that tried to rectify the issues over roughly 18 to 24 months then get dropped as the state of the art had moved beyond it.
Bell and the USAF floated, for a short time, the idea of production of the X-5 as a lightweight, low cost fighter but dropped the idea because of the plane's vicious tendencies in flight.

That being said, would you say, compared to the Focke-Wulf Ta-183, the Messerschmitt Me P.1101 does not have the same realized potential in the time required for it to be useful before being passed over? I recall such and such a South American country working with Kurt Tank post-war to develop a better-engineered version of the Ta-183 and that it flew rather well. Correct me here if I am wrong of course. Just food for discussion.

The Focke Wulf design had more potential to work. Postwar, Kurt Tank designed and produced what was pretty much a slightly better variant of the Ta 183 in Argentina, the FMA IAe 33 Pulqui II. While only four prototypes were produced, these were flown enough to find the aircraft was generally workable except at the upper edges of its performance envelope. At the upper end of performance, the plane exhibited instability, and serious stall issues. While Tank and other engineers on the project worked to rectify these issues they were never eliminated before the project ended. I would note, that these sorts of problems cropped up a lot with every design in the late 1940's so it isn't all just poor engineering, but also a lack of knowledge of high subsonic and transonic flight regimes.
A combination of financial and political instability coupled with lack of a sufficiently large, skilled workforce to build the planes in Argentina doomed the project.

The Ta-183 was Multhopps baby, he went to work in England right after the war before ending up in the US.

And I wouldn't really consider the Pulqui to be a "slightly better variant" - its more like a conservative execution of some of the 183s ideas. Its not trying to build a flying wing with a small fuselage and small trimming surface, which was the whole point of the 183 as originally pursued by Multhopp. Nor is it doing the quite simply brilliant structural design and manufacturing breakdown of the 183, which is pretty much the reason that design was still being pursued even after significant doubts about its aerodynamics had been raised.

So would the T-tail modification of the aircraft not be enough to improve the spin issues? (I am not that well versed in this topic, so I apologize if this question sounds a bit weird.)

As I understand it, T-tails create stability issues of their own on aircraft with swept, tapered wings. When a swept wing stalls, the center of lift moves forward, pitching the aircraft up. Under these conditions, turbulent air from the wing blankets a high-mounted tail--especially a T-tail--and reduces or eliminates the latter's control power. The stall characteristics of highly tapered wings like the P.1101's magnify the effect. As a result, tail planes have been placed low on the tail plane or fuselage on most successful high-performance aircraft since.

So, if anything, I'd expect a T-tail to exacerbate the overall handling characteristics.

The big issue with T-tails at speed is pitchdown. The Voodoo was speed limited because of this not engine power as is typical. Deep stall is an issue with T-tails at any speed unless the moment arm is really long.

Of note here is that while the Messerschmitt P 1101 never flew, the prototype was delivered to Bell Aircraft in the US following the war where it was closely copied--with some improvements like being able to change the wing sweep in flight-- as the Bell X-5. So, we have some idea of how the Messerschmitt design would have performed in flight.
The Bell X-5 was considered somewhat dangerous to fly and had very vicious spin and stall characteristics (sort of like the P-39 maybe?). Both aircraft were really too small to be fitted with a useful armament or fire control systems. The Bell design did have some use in furthering both swept wing performance as well as in development of variable wing position aircraft. The Bell design was however much better than the competing Navy Grumman XF10F Jaguar that was a veritable death trap to fly.

Would the production version of the P.1101, which was intended to have been just a bit larger, have been better for housing armament and other systems?

Interesting question - was the production version of the P 1101 intended to have been just a bit larger?
The original planned experimental version of the P 1101 was set out in drawing XVIII/138 of November 8, 1944. It shows an aircraft 8.815m long with a wingspan of 8.08m.
The original planned series version of the P 1101 was set out in drawing XVIII/130 of November 1, 1944. It was 8.915m long, also with a wingspan of 8.08m.
So, circa November 1944, the series version was 10cm longer - not really a massive amount of additional space for housing armament and other systems.
By the end of February 1945, while the experimental version of the design had remained fixed, the series version had been significantly altered. The data presented to the project comparison meeting at that point gives a wingspan of 8.25m but no fuselage length is offered. However, using the drawing included in the meeting documents, and the 8.25m span (the numbers on the best known copy of the drawing are too blurry to read), it is possible to determine that the fuselage length was about 8.94m.
It would seem that the series production version of the P 1101 was intended to be just a bit larger than the experimental version - but only to the tune of 40mm additional wingspan and 125mm in length. Probably not enough to make much difference, load-wise.

Was the P 1101 considered as a night fighter? Yes it was. The second known version, shown in drawing XVIII/113 of August 30, 1944, shows a design that was intended to be optionally extendable by adding a 650mm fuselage section - turning it into a two seater. Presumably this is is what LePage was basing his drawing on (though his drawing only bears a passing resemblance to the actual design). This design, with this feature, was discussed at a comparison meeting on September 10, 1944, and it wasn't actually made explicit that the extra seat was for a radar operator (there's no mention of installing radar equipment or night-fighting at the meeting) - it may only have been intended to make the aircraft suitable for conversion to a trainer.
In the Messerschmitt construction description of November 2, 1944, the P 1101 is offered as a single-seat 'Wilde Sau' night fighter (see attached). There's no known mention of it as a night fighter after this.

Interesting question - was the production version of the P 1101 intended to have been just a bit larger?
The original planned experimental version of the P 1101 was set out in drawing XVIII/138 of November 8, 1944. It shows an aircraft 8.815m long with a wingspan of 8.08m.
The original planned series version of the P 1101 was set out in drawing XVIII/130 of November 1, 1944. It was 8.915m long, also with a wingspan of 8.08m.
So, circa November 1944, the series version was 10cm longer - not really a massive amount of additional space for housing armament and other systems.
By the end of February 1945, while the experimental version of the design had remained fixed, the series version had been significantly altered. The data presented to the project comparison meeting at that point gives a wingspan of 8.25m but no fuselage length is offered. However, using the drawing included in the meeting documents, and the 8.25m span (the numbers on the best known copy of the drawing are too blurry to read), it is possible to determine that the fuselage length was about 8.94m.
It would seem that the series production version of the P 1101 was intended to be just a bit larger than the experimental version - but only to the tune of 40mm additional wingspan and 125mm in length. Probably not enough to make much difference, load-wise.

Was the P 1101 considered as a night fighter? Yes it was. The second known version, shown in drawing XVIII/113 of August 30, 1944, shows a design that was intended to be optionally extendable by adding a 650mm fuselage section - turning it into a two seater. Presumably this is is what LePage was basing his drawing on (though his drawing only bears a passing resemblance to the actual design). This design, with this feature, was discussed at a comparison meeting on September 10, 1944, and it wasn't actually made explicit that the extra seat was for a radar operator (there's no mention of installing radar equipment or night-fighting at the meeting) - it may only have been intended to make the aircraft suitable for conversion to a trainer.
In the Messerschmitt construction description of November 2, 1944, the P 1101 is offered as a single-seat 'Wilde Sau' night fighter (see attached). There's no known mention of it as a night fighter after this.

View attachment 651919

I'd like to add that the initial problems with the P-1101s armament installation centered around CG, ammo routing and ground handling difficulties. These issues were identified early, maybe because of RLM review, and a better solution was one of the drivers for the single engine jet fighter designs that Messerschmitt pursued from late 44 on.

Also have you ever come across a report of a 262 being flight tested with a 1101 wing? Going from memory, it was alleged to have been installed at rib 6 which is the outer engine edge.

 

[newsdeskdan]

I'd like to add that the initial problems with the P-1101s armament installation centered around CG, ammo routing and ground handling difficulties. These issues were identified early, maybe because of RLM review, and a better solution was one of the drivers for the single engine jet fighter designs that Messerschmitt pursued from late 44 on.

Also have you ever come across a report of a 262 being flight tested with a 1101 wing? Going from memory, it was alleged to have been installed at rib 6 which is the outer engine edge.

According to Hornung's Projektuebergabe of November 10, 1944, the P 1101's wing structure from rib 21 to rib 7 was the Me 262's wing structure but with a new enlarged end cap added. The outer aileron was extended onto the end cap.
I guess the end caps might have been tested on an Me 262 but if so I've never heard of that happening.

The project comparison meeting of September 10, 1944, didn't go as far as to discuss armament installation and the P 1101 was withdrawn from consideration by the Chef-TLR from then until the end of Feb 1945 (with the P 1106 being pitched on its own in December 1944, and the P 1106 and P 1110 being pitched in January 1945).
At the end of Feb 1945, Messerschmitt finally resubmitted a P 1101 variant for consideration alongside a revised P 1110 and the new P 1111.
But from December 22, 1944, Messerschmitt itself was in charge of assessing day fighter projects. The internal version of the pre-end of Feb comparison meeting report (which includes these assessments) does indicate that armament is a weakness for the P 1101 insofar as it can only carry 4 x MK 108 in its nose.
I'm not aware of any issues being raised about the P 1101's armament installation during 1944.

 

[sienar]

According to Hornung's Projektuebergabe of November 10, 1944, the P 1101's wing structure from rib 21 to rib 7 was the Me 262's wing structure but with a new enlarged end cap added. The outer aileron was extended onto the end cap.
I guess the end caps might have been tested on an Me 262 but if so I've never heard of that happening.

It was in a Russian book. I think it said this testing resulted in the slats being enlarged.

Either way I think there was some big change in the 1101s wing. Voigt, in a post war interrogation, says that they used modified naca airfoils with an enlarged LE radius and modified thickness to reduce tip stall while also simplifying construction. The slat and aileron could be of a constant section and there was a bit of a structural benefit as well.

There are drawings of one such wing and P1101 in Randinger and Schlicks Messerschmitt Geheimproject.

The project comparison meeting of September 10, 1944, didn't go as far as to discuss armament installation and the P 1101 was withdrawn from consideration by the Chef-TLR from then until the end of Feb 1945 (with the P 1106 being pitched on its own in December 1944, and the P 1106 and P 1110 being pitched in January 1945).
At the end of Feb 1945, Messerschmitt finally resubmitted a P 1101 variant for consideration alongside a revised P 1110 and the new P 1111.
But from December 22, 1944, Messerschmitt itself was in charge of assessing day fighter projects. The internal version of the pre-end of Feb comparison meeting report (which includes these assessments) does indicate that armament is a weakness for the P 1101 insofar as it can only carry 4 x MK 108 in its nose.
I'm not aware of any issues being raised about the P 1101's armament installation during 1944.

Le Fana Hors Serie #42 explicitly says that armament issues were identified as one of the major weaknesses of the P1101 in fall of 1944;

"A l'automne de 1944, plus le travail avançait sur
le P1101 et plus le doute croissait face aux pro-
blèmes qui apparaissaient de plus en plus sérieux
et importants. Les principaux étaient:

-le manque d'espace pour l'armementet une quan-
tité limitée de munitions ;
-la complexité du logement des atterrisseurs prin-
cipaux. A la mi-octobre, Willy Messerschmitt pro-
posa pour le 1101 un train rétracta ble vers l'avant,
et son esquisse fut plus tard dessinée avec plus de
précision;
-la disposition des charges principales dans le fuse lage, ce qui l'alourdissait;
-plus grave : une vitesse maximale calculée plus
basse que prévue. En plus, à cause de la forme du
fuselage qui, avec ses cadres oblongs s'éloignait
du fuseau à section circulaire, les calculs présen-
taient des incertitudes.
-la position du moteur générait des couples selon
la poussée (problèmes de compensation)."

Given the large number of original Messerschmitt drawings in that issue, with almost all of them listed as coming from the EADS archive, I am inclined to trust that Le Fana had a good reason for writing that even if they unfortunately didn't list the source.

The above then leads directly into Le Fana discussing the P.1106. While they don't talk about armament much here, they do say "Dès le départ, le P1106 reçut un plus grand volume de carburant (1200 kg au lieu de 1069 kg, soit 1350 1) dans la moitié supérieure du fuselage entre les armes et le pilote."

And if one looks at the early P1106 and P1110 of late 1945, Messerschmitt has clearly chosen just about the simplest armament installation possible with far more flexibility than the P1101 offered. Now obviously there would need to be some kind of proof to show that the P1106 layout was chosen in-part because of the armament issue in P1101, but I think we can say that armament was one of the concerns Mess. was carrying forward from P1101. The subsequent designs show much better armament packaging that is a strong indicator of this imho.

 

[newsdeskdan]

Le Fana Hors Serie #42 explicitly says that armament issues were identified as one of the major weaknesses of the P1101 in fall of 1944;

"A l'automne de 1944, plus le travail avançait sur
le P1101 et plus le doute croissait face aux pro-
blèmes qui apparaissaient de plus en plus sérieux
et importants. Les principaux étaient:

-le manque d'espace pour l'armementet une quan-
tité limitée de munitions ;


Given the large number of original Messerschmitt drawings in that issue, with almost all of them listed as coming from the EADS archive, I am inclined to trust that Le Fana had a good reason for writing that even if they unfortunately didn't list the source.

The above then leads directly into Le Fana discussing the P.1106. While they don't talk about armament much here, they do say "Dès le départ, le P1106 reçut un plus grand volume de carburant (1200 kg au lieu de 1069 kg, soit 1350 1) dans la moitié supérieure du fuselage entre les armes et le pilote."

And if one looks at the early P1106 and P1110 of late 1945, Messerschmitt has clearly chosen just about the simplest armament installation possible with far more flexibility than the P1101 offered. Now obviously there would need to be some kind of proof to show that the P1106 layout was chosen in-part because of the armament issue in P1101, but I think we can say that armament was one of the concerns Mess. was carrying forward from P1101. The subsequent designs show much better armament packaging that is a strong indicator of this imho.

I have that Le Fana but it's in one of several dozen massive boxes in my garage and currently inaccessible. I do recall that it had some great drawings in, though. As I said, Messerschmitt acknowledges prior to the Feb 27-28 meeting, in the pre-meeting report of Feb 26, that lack of space is an issue for the P 1101's armament.
Regarding the P 1106 - the general configuration doesn't appear to have allowed much, if any, more space for armament than that of the P 1101. Nearly all versions seem to have been proposed with 2 x MK 108, the same as the P 1101.
In terms of fuel, Le Fana seems to be referencing a version of the P 1106 from a spec sheet dated 13.12.44, which does give a fuel capacity of 1200kg. However, there are two drawings that give different fuel tank capacities:
Drawing XVIII/151 - 1 x 200 litre tank over the engine, 1 x 1100 litre tank over the engine + 150 litres in the wings. Total = 1450 litres.
Drawing XVIII/154 - 1800 litres in a single massive tank over the engine.
There are several other different versions in drawings but these don't show tank capacity. Also, another spec sheet, dated Feb 17, 1945 - presumably just about the last word on the P 1106 - gives fuel capacity of either 900 litres in a rubber tank or 1300 litres in "dicht. geniet. Rumpf'(?). This last version mentions 3 weapons (although it doesn't specify exactly what they are). But by now the P 1101 had been redesigned to take four cannon (as shown in the pre-meeting report of Feb 26).
It's worth mentioning that the Messerschmitt designs tended to only show the weaponry required by the spec they had been designed to. So the P 1101 and P 1106 only had 2 x MK 108 because that's what the spec said they had to include. Later specs asked for more weapons.
In terms of P 1101 wings, plans were certainly drawn up to give the prototype a different set of wings but whether these were ever carried through into the actual construction is unclear (and try as I might I could find no reference to even wind tunnel testing, let alone practical tests by attachment to an Me 262. That's not to say it's impossible but there doesn't seem to be any known evidence for it). The documents relating to the developed version are from the Messerschmitt Probü (projects office) and later the Stabü (staff office) rather than the Kobü (construction office).
I would guess that the wings of the prototype as-built were the modified Me 262 units, as I mentioned. Work on developing the second set of wings was ongoing even towards the end of March 1945.

 

[ArmchairSamurai]

According to Hornung's Projektuebergabe of November 10, 1944, the P 1101's wing structure from rib 21 to rib 7 was the Me 262's wing structure but with a new enlarged end cap added. The outer aileron was extended onto the end cap.
I guess the end caps might have been tested on an Me 262 but if so I've never heard of that happening.

It was in a Russian book. I think it said this testing resulted in the slats being enlarged.

Either way I think there was some big change in the 1101s wing. Voigt, in a post war interrogation, says that they used modified naca airfoils with an enlarged LE radius and modified thickness to reduce tip stall while also simplifying construction. The slat and aileron could be of a constant section and there was a bit of a structural benefit as well.

There are drawings of one such wing and P1101 in Randinger and Schlicks Messerschmitt Geheimproject.

The project comparison meeting of September 10, 1944, didn't go as far as to discuss armament installation and the P 1101 was withdrawn from consideration by the Chef-TLR from then until the end of Feb 1945 (with the P 1106 being pitched on its own in December 1944, and the P 1106 and P 1110 being pitched in January 1945).
At the end of Feb 1945, Messerschmitt finally resubmitted a P 1101 variant for consideration alongside a revised P 1110 and the new P 1111.
But from December 22, 1944, Messerschmitt itself was in charge of assessing day fighter projects. The internal version of the pre-end of Feb comparison meeting report (which includes these assessments) does indicate that armament is a weakness for the P 1101 insofar as it can only carry 4 x MK 108 in its nose.
I'm not aware of any issues being raised about the P 1101's armament installation during 1944.

Le Fana Hors Serie #42 explicitly says that armament issues were identified as one of the major weaknesses of the P1101 in fall of 1944;

"A l'automne de 1944, plus le travail avançait sur
le P1101 et plus le doute croissait face aux pro-
blèmes qui apparaissaient de plus en plus sérieux
et importants. Les principaux étaient:

-le manque d'espace pour l'armementet une quan-
tité limitée de munitions ;
-la complexité du logement des atterrisseurs prin-
cipaux. A la mi-octobre, Willy Messerschmitt pro-
posa pour le 1101 un train rétracta ble vers l'avant,
et son esquisse fut plus tard dessinée avec plus de
précision;
-la disposition des charges principales dans le fuse lage, ce qui l'alourdissait;
-plus grave : une vitesse maximale calculée plus
basse que prévue. En plus, à cause de la forme du
fuselage qui, avec ses cadres oblongs s'éloignait
du fuseau à section circulaire, les calculs présen-
taient des incertitudes.
-la position du moteur générait des couples selon
la poussée (problèmes de compensation)."

Given the large number of original Messerschmitt drawings in that issue, with almost all of them listed as coming from the EADS archive, I am inclined to trust that Le Fana had a good reason for writing that even if they unfortunately didn't list the source.

The above then leads directly into Le Fana discussing the P.1106. While they don't talk about armament much here, they do say "Dès le départ, le P1106 reçut un plus grand volume de carburant (1200 kg au lieu de 1069 kg, soit 1350 1) dans la moitié supérieure du fuselage entre les armes et le pilote."

And if one looks at the early P1106 and P1110 of late 1945, Messerschmitt has clearly chosen just about the simplest armament installation possible with far more flexibility than the P1101 offered. Now obviously there would need to be some kind of proof to show that the P1106 layout was chosen in-part because of the armament issue in P1101, but I think we can say that armament was one of the concerns Mess. was carrying forward from P1101. The subsequent designs show much better armament packaging that is a strong indicator of this imho.

This will probably be a stupid question, but post-war photos of the prototype at Bell Aircraft Company have been painted on either side with different armament installation profiles. Does this give any indication on how the Germans may have installed them or does it instead highlight how awkward it would have been to install anything at all in the nose?

 

[Justo Miranda]

According to Hornung's Projektuebergabe of November 10, 1944, the P 1101's wing structure from rib 21 to rib 7 was the Me 262's wing structure but with a new enlarged end cap added. The outer aileron was extended onto the end cap.
I guess the end caps might have been tested on an Me 262 but if so I've never heard of that happening.

It was in a Russian book. I think it said this testing resulted in the slats being enlarged.

Either way I think there was some big change in the 1101s wing. Voigt, in a post war interrogation, says that they used modified naca airfoils with an enlarged LE radius and modified thickness to reduce tip stall while also simplifying construction. The slat and aileron could be of a constant section and there was a bit of a structural benefit as well.

There are drawings of one such wing and P1101 in Randinger and Schlicks Messerschmitt Geheimproject.

The project comparison meeting of September 10, 1944, didn't go as far as to discuss armament installation and the P 1101 was withdrawn from consideration by the Chef-TLR from then until the end of Feb 1945 (with the P 1106 being pitched on its own in December 1944, and the P 1106 and P 1110 being pitched in January 1945).
At the end of Feb 1945, Messerschmitt finally resubmitted a P 1101 variant for consideration alongside a revised P 1110 and the new P 1111.
But from December 22, 1944, Messerschmitt itself was in charge of assessing day fighter projects. The internal version of the pre-end of Feb comparison meeting report (which includes these assessments) does indicate that armament is a weakness for the P 1101 insofar as it can only carry 4 x MK 108 in its nose.
I'm not aware of any issues being raised about the P 1101's armament installation during 1944.

Le Fana Hors Serie #42 explicitly says that armament issues were identified as one of the major weaknesses of the P1101 in fall of 1944;

"A l'automne de 1944, plus le travail avançait sur
le P1101 et plus le doute croissait face aux pro-
blèmes qui apparaissaient de plus en plus sérieux
et importants. Les principaux étaient:

-le manque d'espace pour l'armementet une quan-
tité limitée de munitions ;
-la complexité du logement des atterrisseurs prin-
cipaux. A la mi-octobre, Willy Messerschmitt pro-
posa pour le 1101 un train rétracta ble vers l'avant,
et son esquisse fut plus tard dessinée avec plus de
précision;
-la disposition des charges principales dans le fuse lage, ce qui l'alourdissait;
-plus grave : une vitesse maximale calculée plus
basse que prévue. En plus, à cause de la forme du
fuselage qui, avec ses cadres oblongs s'éloignait
du fuseau à section circulaire, les calculs présen-
taient des incertitudes.
-la position du moteur générait des couples selon
la poussée (problèmes de compensation)."

Given the large number of original Messerschmitt drawings in that issue, with almost all of them listed as coming from the EADS archive, I am inclined to trust that Le Fana had a good reason for writing that even if they unfortunately didn't list the source.

The above then leads directly into Le Fana discussing the P.1106. While they don't talk about armament much here, they do say "Dès le départ, le P1106 reçut un plus grand volume de carburant (1200 kg au lieu de 1069 kg, soit 1350 1) dans la moitié supérieure du fuselage entre les armes et le pilote."

And if one looks at the early P1106 and P1110 of late 1945, Messerschmitt has clearly chosen just about the simplest armament installation possible with far more flexibility than the P1101 offered. Now obviously there would need to be some kind of proof to show that the P1106 layout was chosen in-part because of the armament issue in P1101, but I think we can say that armament was one of the concerns Mess. was carrying forward from P1101. The subsequent designs show much better armament packaging that is a strong indicator of this imho.

This will probably be a stupid question, but post-war photos of the prototype at Bell Aircraft Company have been painted on either side with different armament installation profiles. Does this give any indication on how the Germans may have installed them or does it instead highlight how awkward it would have been to install anything at all in the nose?

Here

 

[newsdeskdan]

This will probably be a stupid question, but post-war photos of the prototype at Bell Aircraft Company have been painted on either side with different armament installation profiles. Does this give any indication on how the Germans may have installed them or does it instead highlight how awkward it would have been to install anything at all in the nose?

It goes without saying that the prototype was unarmed and was never designed to have any armament.
There's no known wartime configuration of the P 1101 with six MG 151s. By the end of Feb it was considered that normal armament for the production model would be two MK 108s with an additional two MK 108s possible. The side of the aircraft showing two MK 108s is inaccurate - the lower 108s (the two that would be installed in standard configuration) were below and to the sides of the pilot while the upper ones, if installed, would be further back - in the fuselage under the wings.
Why Bell would paint inaccurate series production model armament options onto an unarmed prototype is unclear.

 

[sienar]

Le Fana Hors Serie #42 explicitly says that armament issues were identified as one of the major weaknesses of the P1101 in fall of 1944;

"A l'automne de 1944, plus le travail avançait sur
le P1101 et plus le doute croissait face aux pro-
blèmes qui apparaissaient de plus en plus sérieux
et importants. Les principaux étaient:

-le manque d'espace pour l'armementet une quan-
tité limitée de munitions ;


Given the large number of original Messerschmitt drawings in that issue, with almost all of them listed as coming from the EADS archive, I am inclined to trust that Le Fana had a good reason for writing that even if they unfortunately didn't list the source.

The above then leads directly into Le Fana discussing the P.1106. While they don't talk about armament much here, they do say "Dès le départ, le P1106 reçut un plus grand volume de carburant (1200 kg au lieu de 1069 kg, soit 1350 1) dans la moitié supérieure du fuselage entre les armes et le pilote."

And if one looks at the early P1106 and P1110 of late 1945, Messerschmitt has clearly chosen just about the simplest armament installation possible with far more flexibility than the P1101 offered. Now obviously there would need to be some kind of proof to show that the P1106 layout was chosen in-part because of the armament issue in P1101, but I think we can say that armament was one of the concerns Mess. was carrying forward from P1101. The subsequent designs show much better armament packaging that is a strong indicator of this imho.

I have that Le Fana but it's in one of several dozen massive boxes in my garage and currently inaccessible. I do recall that it had some great drawings in, though. As I said, Messerschmitt acknowledges prior to the Feb 27-28 meeting, in the pre-meeting report of Feb 26, that lack of space is an issue for the P 1101's armament.
Regarding the P 1106 - the general configuration doesn't appear to have allowed much, if any, more space for armament than that of the P 1101. Nearly all versions seem to have been proposed with 2 x MK 108, the same as the P 1101.
In terms of fuel, Le Fana seems to be referencing a version of the P 1106 from a spec sheet dated 13.12.44, which does give a fuel capacity of 1200kg. However, there are two drawings that give different fuel tank capacities:
Drawing XVIII/151 - 1 x 200 litre tank over the engine, 1 x 1100 litre tank over the engine + 150 litres in the wings. Total = 1450 litres.
Drawing XVIII/154 - 1800 litres in a single massive tank over the engine.
There are several other different versions in drawings but these don't show tank capacity. Also, another spec sheet, dated Feb 17, 1945 - presumably just about the last word on the P 1106 - gives fuel capacity of either 900 litres in a rubber tank or 1300 litres in "dicht. geniet. Rumpf'(?). This last version mentions 3 weapons (although it doesn't specify exactly what they are). But by now the P 1101 had been redesigned to take four cannon (as shown in the pre-meeting report of Feb 26).
It's worth mentioning that the Messerschmitt designs tended to only show the weaponry required by the spec they had been designed to. So the P 1101 and P 1106 only had 2 x MK 108 because that's what the spec said they had to include. Later specs asked for more weapons.
In terms of P 1101 wings, plans were certainly drawn up to give the prototype a different set of wings but whether these were ever carried through into the actual construction is unclear (and try as I might I could find no reference to even wind tunnel testing, let alone practical tests by attachment to an Me 262. That's not to say it's impossible but there doesn't seem to be any known evidence for it). The documents relating to the developed version are from the Messerschmitt Probü (projects office) and later the Stabü (staff office) rather than the Kobü (construction office).
I would guess that the wings of the prototype as-built were the modified Me 262 units, as I mentioned. Work on developing the second set of wings was ongoing even towards the end of March 1945.

View attachment 652170

I found what I was thinking of. CIOS German High Speed Planes Development.


Also Le Fana does contain drawings of the V1 with armament. Actually several of them with the 004 and one with the 011.



Now in the above drawing there are two interesting things going on with the armament. First is that no ammo or anything of the sort is show. The second is that the guns are mounted sideways. I don't think I've ever seen a Mk108 mounted like that before. And looking at the actual volume available its not hard to see why;

If you account for the cockpit then there is very little room to make the ammo feeding work any other way than mounting the gun sideways. And this does line up with what I remember reading in an interrogation, where the ammo feed was cited as a constant problem with the design.

I will also add that its not just about the volume that is available, but how readily you can exploit it as well. In the P1101 there is a whole lot going on in the vicinity of the canons. What happens if they need to be swapped out with something different? Or the ammo feed to alteration to stop jamming? The odds of those alterations possibly running into or requiring alteration to a hydraulic line for the front gear, electrical line, vacuum, ect, ect are high. The way things are packaged in the P1101 just isn't conductive to easily modifying the armament and it could potentially cost a lot of manhours to do so - something Mess was aware they didn't have a lot of. Compare this to the later designs where the armament is either segregated or restricted to sharing the same space with one thing, ie gear. The P1106 armament installation doesn't pose any routing challenges if it has to be radically changed. There is plenty of flexibility for having a simple ammo storage and feed system.

 

[newsdeskdan]

If you account for the cockpit then there is very little room to make the ammo feeding work any other way than mounting the gun sideways. And this does line up with what I remember reading in an interrogation, where the ammo feed was cited as a constant problem with the design.

I will also add that its not just about the volume that is available, but how readily you can exploit it as well. In the P1101 there is a whole lot going on in the vicinity of the canons. What happens if they need to be swapped out with something different? Or the ammo feed to alteration to stop jamming? The odds of those alterations possibly running into or requiring alteration to a hydraulic line for the front gear, electrical line, vacuum, ect, ect are high. The way things are packaged in the P1101 just isn't conductive to easily modifying the armament and it could potentially cost a lot of manhours to do so - something Mess was aware they didn't have a lot of. Compare this to the later designs where the armament is either segregated or restricted to sharing the same space with one thing, ie gear. The P1106 armament installation doesn't pose any routing challenges if it has to be radically changed. There is plenty of flexibility for having a simple ammo storage and feed system.

The P 1101 series production model was always intended to have its guns mounted sideways. The attached two drawings are from early November 1944. And all the source material I have says that the prototype was never meant to be armed.
As further evidence, I offer a page from 'Ministry of Aircraft Production - Visit to Messerschmitt Plant at Oberammergau - Bavaria - June 18th-25th 1945. Report by Mr R. M. Clarkson, de Havilland Aircraft Co.', which is AVIA 10/113 at the National Archives (photo of the page attached below).
Clarkson went to Oberammergau and examined the P 1101 in person. He wrote:
"This very ugly aircraft was designed originally as an operational fighter, but was being built as a research aircraft only, no provision for guns, etc. being made. As a fighter it weighted 8900 lb and had a wing loading of 52.3 lb./sq.ft.
The wing has a sweepback of 40-degrees and is thinner at the root than at the tip - 8% T/C at root and 12% T/C at tip. * This was done to reduce the interference between wing and fuselage at high Mach numbers.
Leading edge slots are used, being 24% C. at tip and 13% C. at root.
All tail surfaces have a T/C of 6%.
The following estimated performance figures were obtained:-
Max. speed at 23,000 ft. 612 mph.
Rate of climb at Sea Level 4330ft./min.
Landing Speed with 1/3 fuel in tanks 107 mph.
Take off Run 775 yds.
Landing Run 625 yds.
The construction of this aircraft is approximately 75% complete and has been assembled by the Americans at Oberammergau. The wing is of metal construction similar to the Me 262 and the empennage is wooden. The rather crude cowling round the engine is steel, spot-welded - the reason is not very apparent, unless it is a fire risk."

In attempting to find the source for your assertion about weapons packaging, I had a look through the fairly lengthy interrogation report on Woldemar Voigt to see whether he had anything to say about it (A.D.I. (K) Report No. 1/1946) and although he does talk about the design it's mostly in relation to its wings - the weapons installation doesn't get a mention.
I checked the USSAFE Technical Intelligence Report No. E-16 Investigation of Me Target at Oberammergau, 7 June 1945, and although that does briefly mention the P 1101, there's no detailed discussion of its configuration.
I then went to CIOS XXXII-41, Messerschmitt Advanced Fighter Design, Reported by Lt. Comdr. M. A. Biot, USNR Nav Tec Mis Eu. This just says: "2. Outline of Design Program. (a) The first project, P-1101, was carried out at the personal wish of Prof. Messerschmitt for the purpose of collecting experimental data on high speed aircraft. this project was pushed ahead and carried out in great detail without considering the military applications as essential for the design. This project does not approximate the optimum solution. In this airplane the pilot sits forward and the fuel tank is located above the engine. A two (2) meter span model of this airplane was tested in the wind tunnel at Berlin-Adlershof. The prototype had been completed and was blown up before the arrival of our troops. This prototype had a Jumo 004 engine which was later to be replaced by the HeS 011. This engine was under development and was to be ready for use about six (6) months. The trust [sic] of this engine at sea level is 1,300 kilograms."
I can't think of anywhere else to look. Can you remember anything about whose interrogation it was or where it appeared (I have approximately 500 sheets of Messerschmitt design data, reports and drawings on the P 1101 - dating from August 1944 to March 1945 - and there's no mention of weapons packaging issues on any of them - and they discuss every other design detail, including, for example, placement of the compass)? Looking at the drawings, you're right, it does look as though packaging would have been an issue, but I cannot find anything contemporary which actually says that it was.

We know that the P 1101 had been withdrawn from consideration in the 1-TL-Jaeger fighter competition by December 1944, but that Messerschmitt then decided to re-enter it for the Feb 27-28 comparison meeting. I would guess that the two drawings from Le Fana are an attempt to show how the V1 could potentially be configured for a weapons installation mock-up - in the event that the P 1101 design was selected for further development during the Feb 27-28 meeting. But it wasn't, and so no further effort was made to contrive any sort of weapons installation mock-up.
As I've already said, Messerschmitt acknowledged that a weakness of the P 1101 was the lack of space to expand its armament further.

 

[iverson]

This will probably be a stupid question, but post-war photos of the prototype at Bell Aircraft Company have been painted on either side with different armament installation profiles. Does this give any indication on how the Germans may have installed them or does it instead highlight how awkward it would have been to install anything at all in the nose?

If anything, I think the latter. I can't recall where, but I remember reading that the silhouettes of guns were paper cutouts and compared MK108 installations to a six 0.50-in Browning installation.

 

[Apophenia]

... I can't recall where, but I remember reading that the silhouettes of guns were paper cutouts ...

The MK 108s, at least, were attached by two metal fasteners. Possibly light sheet metal cutouts?

 

[Temistocle]

A color picture of the Me-P.1011 V1 at Oberammergau in May 1945. It is interesting to note the wings (or at least the right one, slat apart) are camouflaged. From Flugzeug Classic, June 2020, page 9.

 

[Vahe Demirjian]

Re: Messerschmitt P. 1101/VIII-104 « Sichelflügel » ("crescent wing")

"Sichelflügel" drawing here ...

There's a Messerschmitt company drawing on page 112 of Luftwaffe Secret Projects: Strategic Bombers 1935-1945 showing the same design but with the drawing label P.1101/XVIII-105 (paradoxically, the drawing of the Zerstörer version included under company label P.1101/XVIII-105 is identified as the P.1101/XVIII-104 in Luftwaffe Secret Projects: Ground Attack & Special Purpose Aircraft), even though a company drawing with the drawing number P.1101/XVIII-104 appears in the book Willy Messerschmitt - Pioneer of Aviation Design by Erbert, Kaiser and Peters. Is there any difference between the P.1101/XVIII-104 and P.1101/XVIII-105 despite the fact that the Sichelflügel appears under both numbers?

 

[F.L.]

A color picture of the Me-P.1011 V1 at Oberammergau in May 1945. It is interesting to note the wings (or at least the right one, slat apart) are camouflaged. From Flugzeug Classic, June 2020, page 9.

United Service Organizations troupe posing with a Messerschmitt P.1101 at the Oberbayerische Forschungsanstalt, Oberammergau, Germany, in 1945.

 

[F.L.]

 

[F.L.]

Sad end.

 

[archipeppe]

This is my 3 views about the Me P.1101 that comes from my latest book:

https://www.amazon.com/X_Planes-from-the-X_1-to-the-X_60_-An-Illustrated-History-_Springer-Praxis-Books_/dp/3030863972

 

[ArmchairSamurai]

A color picture of the Me-P.1011 V1 at Oberammergau in May 1945. It is interesting to note the wings (or at least the right one, slat apart) are camouflaged. From Flugzeug Classic, June 2020, page 9.

United Service Organizations troupe posing with a Messerschmitt P.1101 at the Oberbayerische Forschungsanstalt, Oberammergau, Germany, in 1945.
View attachment 701540

Déjà vu?

 

[HoHun]

Hi Basil,

Interesting to see that the Schönwetterjäger would also have a Fug 218 radar. I assume this was for automatic ranging feeding the EZ 42.

Was the FuG 218 really used in that way? I'd have thought that the FuG 218 probably was an "R" variant, providing rear warning. The P-47 and P-51 could also be fitted with rear warning radars, though I am not sure to which degree that was actually done in WW2 - the technology at least seems to have been available.

Regards,

Henning (HoHun)

 

[Foo Fighter]

One of those days so, I am sure this is a daft question asked before. Has anyone done studies on how these late war projects might have actually fared if the got to flying status?

 

[F.L.]

A color picture of the Me-P.1011 V1 at Oberammergau in May 1945. It is interesting to note the wings (or at least the right one, slat apart) are camouflaged. From Flugzeug Classic, June 2020, page 9.

United Service Organizations troupe posing with a Messerschmitt P.1101 at the Oberbayerische Forschungsanstalt, Oberammergau, Germany, in 1945.
View attachment 701540

Déjà vu?

Better quality.

 

[sienar]

Hi Basil,

Interesting to see that the Schönwetterjäger would also have a Fug 218 radar. I assume this was for automatic ranging feeding the EZ 42.

Was the FuG 218 really used in that way? I'd have thought that the FuG 218 probably was an "R" variant, providing rear warning. The P-47 and P-51 could also be fitted with rear warning radars, though I am not sure to which degree that was actually done in WW2 - the technology at least seems to have been available.

Regards,

Henning (HoHun)

There were plans to have the range finding radar mounted on a wing-tip pod.

 

[Airborne2001]

One of those days so, I am sure this is a daft question asked before. Has anyone done studies on how these late war projects might have actually fared if the got to flying status?

As tested with the Bell X-5 that was (mostly) a copy, the aerodynamic layout of the P.1101 was flawed. This could lead to irrecoverable spins at higher wing sweeps. As far as I'm aware I don't think this was encountered at lower sweeps though. I do not know how the different dimensioned production version would have handled with this. I also do not know how the T-Tail version would have handled this either. Would anyone on here with more knowledge in aerodynamics care to shed some knowledge?

 

[HoHun]

Hi Dan,

In the Messerschmitt construction description of November 2, 1944, the P 1101 is offered as a single-seat 'Wilde Sau' night fighter (see attached). There's no known mention of it as a night fighter after this.

View attachment 651919

This type overview had me a bit puzzled about why the fair weather fighter version had an auto pilot too.

By accident, I just came across this document (freely available at the German Bundesarchiv site) ... K.T.B. 8.1./14.1.1945, I'm afraid I can't link the relevant page directly:

https://invenio.bundesarchiv.de/invenio/direktlink/ff268edd-8129-450a-b0e4-6a35d48fc287/

It summarizes a Rüstungsstab meeting on fighter armament chaired by Saur, held on January 10, 1945. The interesting point is that the meeting results in Saur ordering fighters to be fitted with 'course control' with high priority, as it's expected that will significantly reduce aiming errors.

The term for aiming error in the original is "Abkommfehler" ... a technical term that (according to my impression) denotes the difference between the pilot-intended aim point and the direction in which the sight is actually pointing.

I believe the RAF concept of "aim wander" has the same background, with "aim wander" being the average size of the "Abkommfehler".

Now I have to admit that I have no information on how exactcly the autopilot achieved this improvement. I figure that it could have worked as a yaw-damper, or even worked to zero yaw (i. e. to keep the ball centered), if one understands a yaw damper as a device that only zeros the yaw rate.

First time ever I heard of this in a WW2 gunnery context ... it's probably not so different from the autopilot use with real-time bomb sights like the Norden or the Lotfe's, but still!

Regards,

Henning (HoHun)

 

[F.L.]

I'm afraid I can't link the relevant page directly

Can you attach a pdf of this document ?

 

[HoHun]

Hi F.L.,

Can you attach a pdf of this document ?

I'm not sure that would be legally permissible ... you can get there with very few clicks, though:

• First, click this link: https://invenio.bundesarchiv.de/invenio/direktlink/ff268edd-8129-450a-b0e4-6a35d48fc287/
• Click "X" to close the splash screen.
• Click on "Digitalisat anzeigen" for the first entry shown (should be "RL 3/2567 Kriegstagebuch")
• Then drag the slider to page 65 of 370.

Browsing through all of this, it's interesting to see that the Rüstungsstab put a high priority on getting the EZ42 lead-computing gunsight into service, while repeatedly recording "Führer" orders to have the Me 262 to be equipped with heavier guns, like a 5 cm cannon or a battery of 6 x MK 103 machine cannon. Page 65 also points out that an "increase of muzzle velocities delivers no significant increase of the probability of kill, but heavy installation weight". So apparently, the Rüstungsstab didn't agree with the Führer here, and I'm not sure how much attention they actually paid to his orders!

Regards,

Henning (HoHun)

 

[hesham]

From this book.

 

[HoHun]

Hi again,

Now I have to admit that I have no information on how exactcly the autopilot achieved this improvement. I figure that it could have worked as a yaw-damper, or even worked to zero yaw (i. e. to keep the ball centered), if one understands a yaw damper as a device that only zeros the yaw rate.

First time ever I heard of this in a WW2 gunnery context ... it's probably not so different from the autopilot use with real-time bomb sights like the Norden or the Lotfe's, but still!

Regards,

Henning (HoHun)

Luck is on my side ... I just stumbled upon the article "The Birth of Sweepback - Related Research at LFA-Germany" by Peter G. Hamel, and it gives some background on the topic of yaw dampers in WW2 Germany:

https://www.researchgate.net/publication/245430247_Birth_of_Sweepback_Related_Research_at_LuftfahrtforschungsanstaltGermany

The earliest recognition of the need for stability augmentation was given by E. Heinkel on September 20, 1940 while introducing two lectures on the subject. He briefly remarked that longitudinal stability of very fast airplanes will diminish, and that the transition to artificial stability produced by an automatic pilot will become an inevitable necessity in the near future.

One of the lectures on this subject was presented by E. Fischel who for the first time discussed analytical methods by which it is possible to predict the benefits of artificial stability. One of the first applications of artificial stability was concerned with the reduction of directional snaking oscillations which were aircraft configuration dependent, annoying the pilots extremely during tracking tasks. K.-H. Doetsch and E. G. Friedrichs of DVL-Berlin flight-tested in 1944 the first dedicated yaw damper by replacing the rudder of a Henschel Hs 129 with two separate yaw control surfaces, one for pilot manual control and the other for rate gyro controlled yaw damping.

Similar electromechanical aids to aerodynamics were implemented by Richard Vogt to the longitudinal and lateral axes to make the very large flying boats BV 222 and BV 238 with large control forces more pleasant to fly for the pilots. These activities represented also the beginnings of control systems with artificial feel.

Regards,

Henning (HoHun)

 

[HoHun]

Hi again,

It summarizes a Rüstungsstab meeting on fighter armament chaired by Saur, held on January 10, 1945. The interesting point is that the meeting results in Saur ordering fighters to be fitted with 'course control' with high priority, as it's expected that will significantly reduce aiming errors.

In another document from the same archive, the average size of the aiming error is quantified as part of a training document (addressing the gunnery instructors):

https://invenio.bundesarchiv.de/invenio/direktlink/342fff41-bf0b-4fc3-9ccf-f593c0e4923a/

From p. 10 by slider count:

"Die Auswertung von Frontfilmen und Schiessversuche haben ergeben, dass ein Durchschnittsschütze beim Beschuss bewegter Ziele die Hälfte der von ihm abgegebenen Schüsse in 100 m Entfernung in einen Kreis von 2 m Durchmesser zu bringen vermag. Der Radius des 50%igen Streukreises beträgt somit in 100 m Entfernung 1 m, in 1000 m Entfernung 10 m."

Translation:

"The evaluation of gun camera footage and gunnery trials have shown that an average shooter firing at moving targets is able to place half of the shots he fires in a 2 m diameter circle at 100 m range. The radius of the 50% dispersion circle thus amounts to 1 m at 100 m range, to 10 m at 1000 m range."

In other words, an average shooter will hit 50% of his shots in a 20 mil diameter circle. For comparison, the Luftwaffe's gunsight reticle according to the same document is 100 mil in diameter.

From the high priority assigned to the yaw damper, I would conclude that probably the Luftwaffe found that with the help of the yaw damper, an average pilot was able to significantly reduce the size of that circle.

Of course, the good shots could probably achieve a much smaller diameter for their 50% circle ... Eglin Air Foce Base test pilot Don Lopez in "Fighter Pilot's Heaven" notes that in his gun-camera recorded tracking tests, the optimum tracking result he achieved was an accuracy of 0.5 mils - dramatically smaller than the 10 mil the Luftwaffe expected. This was not in a combat situation though, and he had been flying a long series of similar gunnery trials, so he had gotten extremely good at tracking. He actually mentions that a tracking accuracy of 6 mils was considered acceptable by the US ... pretty close to the Luftwaffe's 10 mil figure for actual combat gunnery.

(The often-quoted "only 2% hits" figure for Luftwaffe service pilots is a myth, by the way - most likely a misunderstanding of Ballistic Laboratory Report 727 by Herbert K. Weiss, which notes low hit percentages based on gun camera films. However, if one reads the report carefully, it's clear that Weiss talks about discernible hits, which are only a percentage of all hits score, since not all hits produced "visual effects" clear enough to be recorded on film. Weiss points out that there were kills scored/fires started from attack runs without any discernible hits! )

Regards,

Henning (HoHun)

 

[HoHun]

Hi again,

From the high priority assigned to the yaw damper, I would conclude that probably the Luftwaffe found that with the help of the yaw damper, an average pilot was able to significantly reduce the size of that circle.

The aforemention Herbert K. Weiss in this paper (Ballistic Research Laboratories Memorandum Report No. 462, Airplane Vulnerability and Overall Armament Effectiveness) actually quantifies this, albeit for diving attacks on ground targets:

https://apps.dtic.mil/sti/pdfs/ADA800394.pdf

"The following information regarding tracking errors of a fighter aircraft has been obtained through Wright Field . An F6F-5 fighter was dived at a fixed ground target, and errors in keeping a Mk 8 fixed sight and a Mk 23 gyro sight on the target were photographically recorded. When all errors for all four pilots were averaged, an average error of 2.44 mils was obtained for the Mk8 sight and 1.24 mils for the Mk 23 sight. Air speeds varied between 170 and 310 knots. When all of the tracking data was divided into two speed groups, and elevation and deflection errors listed separately, the following average errors were determined.

Elevation Deflection
230 knots 0.95 1.52m
230 knots 1.09m 1.82m

When the tracking data was separated according to angle of-dive; the following table-was obtained

Elevation Deflection
25° 0.52m 1.44m
25° - 35° 0.88m 1.39m
35° 1.45m 2.44m

The airplane is more difficult to control laterally because coordinated movements of ailerons and rudder are required,, hence:the large deflection errors. The report also comments that the required control forces at high speeds increase tracking difficulty. Speed is also increased as dive angle increases, and it is observed in the report that there is increased difficulty in trimming the airplane in steep dives."

The source for the data quoted by Weiss is given in his paper as "'Experimental Determination of Tracking Inaccuracies of Fixed and Disturbed Computing Gunsights in Fixed Gun Fighter Aircraft", 24 August 1946, prepared by four officers under the direction of Dr. C. S. Draper, Instrumentation Laboratory, Massachusetts Institute of Technology."

(Somehow, the term "Davis-Draper sight" pops up from my memory, but I have no idea what it is about.)

Regards,

Henning (HoHun)