Mustang XP-51F/G/J prototypes

[Steve Pace]

Does anyone have any high res images of these three experimental Mustang prototypes? -SP

 

[toura]

Hi
look at " www.aerofiles.com"
chose " aircraft a to z
and north american
you have your p 51

 

[Johnbr]

From the book Mustang by Robert W Gruenhagen.

 

[Johnbr]

Found better ones.

http://mustangp51.e-monsite.com/rubrique,developpement-2,146969.html

 

[Steve Pace]

Thanks guys...

 

[RAP]

Flight magazine article on P-51F from June 20, 1946.

 

[roadrunner2]

Hello,
where to find XP-51F/G 3 view drawing ?

 

[azlzft]

 

[Ronny]

apparently, this 5 blade P-51 is the fastest P-51 ever tested

 

[yasotay]

Interested in the propeller. Was it a completely new design, or derived from another, like those found on late Marks of the Spitfire?
The five bladed one.

 

[Archibald]

Did you loved "baby Yoda" ? You will love "baby Mustang". It is sooooo cute !

 

[Silencer1]

Seeing pictures of "ultimate" "Mustangs, kindly shared by azlzft, I rapidly noted, that one of the photos in collection is wrong (RAF FB-408, side view) - how Martin MB-5 came here?

I spend few seconds to figure out, that error was mine.

 

[Deleted member 2278]

Interested in the propeller. Was it a completely new design, or derived from another, like those found on late Marks of the Spitfire?
The five bladed one.

The XP-51G was fitted with a Rolls-Royce manufactured Merlin RM.14.SM & one of the pair received a Rotol wooden 5-bladed prop "temporarily". NAA test pilot Bob Chilton said the prop caused directional instability (source: the Crowood tome). Given the 5-bladed props' fairly wide fitment to Spitfires, maybe the lightweight Mustangs needed a little more fin area? The G already had a small fin extension compared with the F model, so a case of more is more? Perhaps the H model's altogether taller fin?

The G model was indeed the fastest but given Chilton's flight with the Rotol is described as "wild", the speed record was most likely achieved by the re-instated Aeroproducts 4-blade.

Some interesting info on the RM.14.SM here:

http://www.wwiiaircraftperformance.org/merlin-lovesey.pdf

 

[kitnut617]

It would have been a new design, viewed looking at the front, the Merlin rotates the propeller counter-clockwise, all the other Spitfires that had 5-blade props were powered by Griffons, which rotated the propeller clockwise.

It's nice to see the photos of the one in RAF markings, and I know the RAF tested a P-51H but this doesn't look like a P-51H. So looking on UK Serials to see what they have for FR408, it's interesting to note UK Serials has it listed as a Kingcobra I -- which it most definitely isn't --

 

[Deleted member 2278]

FR409-411 were the XP-51F above, the second XP-51G (I don't know whether it was actually received but it was allocated the serial) and an ex-USAAF P-51B/Mk.III respectively. 408 was indeed an eval P-63A (as was FZ440) and FR412-on were a batch of (anachronistic given the company) P-40Ms.

UK2 FR408 Bell Kingcobra ex US 42-68937 P-63A.jpg - AviationBanter

UK2 FR408 Bell Kingcobra ex US 42-68937 P-63A.jpg Aviation Photos

www.aviationbanter.com

KN987 was the RAF P-51H.

 

[kitnut617]

OM, yes, now looking at the photos up close with a magnifying glass, the serial number does look like FR409 --

I was puzzled for the longest time as to why NAA put such a huge canopy on them, but finally found evidence as to why. They had raised the whole cockpit up and these nice photos emphasize it very well. I've got a model build going where I'm making all these XP-51's and it took me a while to find a canopy for them, finally found what I need after I had got a couple of FJ-1 Furys and then found I could get aftermarket clear vac canopies.

 

[Justo Miranda]

Hi

 

[yasotay]

Superb! Thank you all. Wonderful information. I suppose that with the ending of the war and the shift to jets any work on the late model P-51was made redundant.

 

[kitnut617]

Given the 5-bladed props' fairly wide fitment to Spitfires, maybe the lightweight Mustangs needed a little more fin area? The G already had a small fin extension compared with the F model, so a case of more is more? Perhaps the H model's altogether taller fin?

In the Rolls Royce Heritage Trust book, Rolls Royce and the Mustang, it explains that when RR were modifying the Mustang Mk.I's to Merlin power and started testing it, they found that the Merlin caused more yaw problems than what the Allison did. Some wind tunnel testing revealed that the aircraft needed more fin area. RR solution was to add 3" to the leading edge of the fin, top to bottom and this resolved the problem. This extension was added to all five of the Mustang X's.
They looked like this below, this is the last iteration of the Mk.X.

 

[Justo Miranda]

North American P-51 Mustang evolution

​

In spring 1943 the Americans launched five programmes to improve the P-51 D performances.

For a weight saving, the airframe was extensively redesigned as XP-51F. To eliminate unnecessary structure, high-strength 75 ST aluminium and plastics were also employed. Principal changes included a much thinner cross-section wing, with straight leading edge, a lighter landing gear with small wheels and removal of the fuel tank behind the pilot.

To save drag, the radiator housing was redesigned with a smaller chin scoop.

The only added weight was due to the fitting of a longer bubble canopy that required one hydraulic device to move.

On February 1944 the XP-51F performing its first flight.

The prototype weighted 1,468 kg (3,229 lbs) less than the P-51 D-NA and was 47 kph (29 mph) faster powered by the same engine. To save weight the standard airscrew was replaced by one hollow-steel, three-bladed Aero Products propeller, the armament was reduced to four 0.50 cal machine guns with 250 rounds per gun and the oil cooler was replaced with a heat exchanger.

The XP-51 G was flown in 9 August 1944, powered by one 1,500 hp. Rolls-Royce Merlin 14 SM engine driving a five-bladed Rotol airscrew with 3.35 m (11 ft) of diameter. The British engine reaching 2,200 hp. emergency power burning 150 octane fuel, 130 per cent more power than the original engine.

The XP-51 G weighted 1,546 kg (3,401 lbs) less than the P-51 D-NA and was 57 kph (35.4 mph) faster.

Only two prototypes were built.

On 3 February, 1945 the P-51 H first flight tests were performed, powered by one Allison V-1650-9 engine, with 370 hp less than the V-1650-7 standard used by the P-51 D-NA. The P-51 H was 81 kph (50 mph) faster and weighted 370 kg (814 lbs) less, with the same armament.

Over 370 units were delivered to the USAAF prior the V-J Day, too late to see actual combat.

The fastest version of the line, named XP-51 J, was flown in 23 April, 1945 powered by one 1,500 hp. Allison V-1710-119 engine which offered over 1,720 hp. at 6,100 m (20,000 ft) altitude, with water injection and 150 octane fuel.

The prototype weighted 1,432 kg (3,150 lbs) less than the P-51 D-NA and was 87 kph (54 mph) faster.

To save drag the cooling systems were redesigned, with coolant and oil radiators in one ventral fairing. The carburettor intake was also moved to the ventral radiator scoop.

Only two prototypes were built.

On July 1944 the British launched a desperate attack against the new German cruise missiles V-1, to face the 'robot offensive' with their high performance interceptors Mustang Mk.III of RAF Squadrons 129, 306 (Polish) and 313 (Polish).

The aerodynamic drag of the V-1 airframe was higher than anticipated, due to low standards of manufacturing, decreasing from projected 900 km/h (559 mph) to the real 640 km/h (398 mph). Fortunately for the Allies this made the new missile susceptible to be intercepted by conventional fighters, but the game was dangerous.

They used to start the attack with a dive to gain speed, moving on to horizontal flight at 230 m behind the missile to be able to shoot it. The calculation of relative speeds was complicated, and some pilots died when firing from a too short distance.

It was necessary to modify the fighters to make them fast enough to intercept the V-1, the Mustang Mk.III changed their exhaust by those of the Spitfire engine that generated less drag, rear view mirrors and armour plates were also stripped. To reduce the drag on some airplanes, the camouflage paint was removed to gain some speed.

During the 'Operation Diver', between June 1944 and March 1945, sixteen squadrons of interceptors used the new aviation fuel ‘150 grade’ produced in the USA. Using trimethylpentane, that fuel had a higher octane-number, so allowed a higher compression and power output.

 

[famvburg]

OM, yes, now looking at the photos up close with a magnifying glass, the serial number does look like FR409 --

I was puzzled for the longest time as to why NAA put such a huge canopy on them, but finally found evidence as to why. They had raised the whole cockpit up and these nice photos emphasize it very well. I've got a model build going where I'm making all these XP-51's and it took me a while to find a canopy for them, finally found what I need after I had got a couple of FJ-1 Furys and then found I could get aftermarket clear vac canopies.

I have some WIPs and had planned to use F2H Banshee canopies. I’ll have to look at the FJ-1s.

 

[kitnut617]

OM, yes, now looking at the photos up close with a magnifying glass, the serial number does look like FR409 --

I was puzzled for the longest time as to why NAA put such a huge canopy on them, but finally found evidence as to why. They had raised the whole cockpit up and these nice photos emphasize it very well. I've got a model build going where I'm making all these XP-51's and it took me a while to find a canopy for them, finally found what I need after I had got a couple of FJ-1 Furys and then found I could get aftermarket clear vac canopies.

I have some WIPs and had planned to use F2H Banshee canopies. I’ll have to look at the FJ-1s.

Look in JAYS Models New Zealand website

TA203 FJ-1 Fury Canopy TA203 FJ-1 Fury Canopy [1:72nd scale] - $5.00 : JAYS Hobby Products, New Zealand

range of vacuum form canopies in 1:72 scale, squadron, tasman, jays

jaysmodelkits.com

 

[kitnut617]

Justo, the XP-51 with the 5-blade prop is the XP-51G

 

[Justo Miranda]

Justo, the XP-51 with the 5-blade prop is the XP-51G

OK

 

[azlzft]

 

[Foo Fighter]

I wonder if the larger canopy had an aerodynamic element to it. I saw an interview with a Mustang pilot who stated that the earlier aircraft were faster due to better aerodynamics compared to the bubble type canopy.

 

[kitnut617]

The P-51H was the production version of these three XP-51's. They made the fuselage sides taller to accommodate the raised cockpit and then placed a regular bubble canopy on top. It was the fastest production P-51 built, so I don't think the aerodynamics were that bad.

 

[2Bravo]

Hi
Does anyone have recent pictures of the XP-51G rebuild by John Morgan? I'm building a big J model and would like to see how his is progressing. it seems to me that the XP-51 models had a rounded windshield without armored glass. Am I wrong? I also noticed that the XP-51G, 343335 John Morgan is rebuilding had an H-Style fin fitted during testing. You will see the difference on the two side views in the thread.

 

[azlzft]

Latest found XP-51F

 

[2Bravo]

Never seen these photos of the F-Model before. These are very clear in contrary to many of the other photos of the XP-51 models. Your photos clearly shows the standard P-51 tailfin on #433333.
The G-model being rebuild must have been refitted with an early H-model tail assembly, if you look through this thread.

 

[yasotay]

I could be wrong, but I thought I saw pictures of the XP-51G restoration effort completed and sitting outside of a hanger.

...or I could have looked at the pictures above.

 

[BarnOwlLover2]

Anyone have any technical or other drawings or illustrations?

 

[meijer]

Latest found XP-51F View attachment 704133View attachment 704134View attachment 704135

Hello Sir

I was enormously pleased to find the three high resulution pictures of the 3rd P-51F here, they are part of AF technical report 5653 dated 4 december 1947 .
In that tech report a fourth picture (picture 158419) was also givven. the one i have attached .

Did you by chance find this three quarter rear view i the same high resolution also?

Eagerly awiting your answer

Sincerely

H Meijer

 

[azlzft]

I found it here, you can ask mjfur

XP-51F/G/J

I'd bet there's a few in the Ebay P-51 thread, but I'm wondering if there's any floating around, preferably in high res but any that can be found will be good of these rare hotrods :)

ww2aircraft.net

Hello Sir

I was enormously pleased to find the three high resulution pictures of the 3rd P-51F here, they are part of AF technical report 5653 dated 4 december 1947 .
In that tech report a fourth picture (picture 158419) was also givven. the one i have attached .

Did you by chance find this three quarter rear view i the same high resolution also?

Eagerly awiting your answer

Sincerely

H Meijer

 

[azlzft]

Color photos

 

[drgondog]

In the Rolls Royce Heritage Trust book, Rolls Royce and the Mustang, it explains that when RR were modifying the Mustang Mk.I's to Merlin power and started testing it, they found that the Merlin caused more yaw problems than what the Allison did. Some wind tunnel testing revealed that the aircraft needed more fin area. RR solution was to add 3" to the leading edge of the fin, top to bottom and this resolved the problem. This extension was added to all five of the Mustang X's.
They looked like this below, this is the last iteration of the Mk.X.

I would offer an addition to the comments. AL 963 had the fin chord extension as you mentioned, but it was preceded by the dorsal fin mod - while the DF mod was deemed slightly less effective, the chord mod was deemed to make the Mustang response to roll input less desirable.

 

[drgondog]

I wonder if the larger canopy had an aerodynamic element to it. I saw an interview with a Mustang pilot who stated that the earlier aircraft were faster due to better aerodynamics compared to the bubble type canopy.

He was wrong. Although the D was heavier due to increased firepower (2x 50 cal plus 600 rnds of ammo) the fuselage/canopy design with better windshield and flow properties, combined with much better pylon reduced P-51 parasite/form drag co-efficients below the P-51B/C. It was clean enough to offset slight increase in Induced Drag due to 500+ pounds of additional GW,

Long after war, David Lednicer confirmed NAA/NACA 1943-1944 wind tunnel tests with sophisticated CFD/Navier Stokes mesh models to compare the two.

I have both the drag reports as well as the CD build up for both (plus P-51H). The P-51H was the cleanest of all despite being a larger airframe/wing design over the B/D (and F/G/J)

The longer canopy profile as well as the longer aft radiator cooling exit cover were contributors to better aerodynamics to offset the increased profile drag of slightly 'taller' fuselage/canopy section.

Further, the NACA 66 series wing, while basically the same thickness/chord ratio as the NAA/NACA 45-100 wing was slightly less draggy in the low CL range of high speed/cruise

 

[drgondog]

North American P-51 Mustang evolution

​

In spring 1943 the Americans launched five programmes to improve the P-51 D performances.

For a weight saving, the airframe was extensively redesigned as XP-51F. To eliminate unnecessary structure, high-strength 75 ST aluminium and plastics were also employed. Principal changes included a much thinner cross-section wing, with straight leading edge, a lighter landing gear with small wheels and removal of the fuel tank behind the pilot.

To save drag, the radiator housing was redesigned with a smaller chin scoop.

The only added weight was due to the fitting of a longer bubble canopy that required one hydraulic device to move.

On February 1944 the XP-51F performing its first flight.

The prototype weighted 1,468 kg (3,229 lbs) less than the P-51 D-NA and was 47 kph (29 mph) faster powered by the same engine. To save weight the standard airscrew was replaced by one hollow-steel, three-bladed Aero Products propeller, the armament was reduced to four 0.50 cal machine guns with 250 rounds per gun and the oil cooler was replaced with a heat exchanger.

The XP-51 G was flown in 9 August 1944, powered by one 1,500 hp. Rolls-Royce Merlin 14 SM engine driving a five-bladed Rotol airscrew with 3.35 m (11 ft) of diameter. The British engine reaching 2,200 hp. emergency power burning 150 octane fuel, 130 per cent more power than the original engine.

The XP-51 G weighted 1,546 kg (3,401 lbs) less than the P-51 D-NA and was 57 kph (35.4 mph) faster.

Only two prototypes were built.

On 3 February, 1945 the P-51 H first flight tests were performed, powered by one Allison V-1650-9 engine, with 370 hp less than the V-1650-7 standard used by the P-51 D-NA. The P-51 H was 81 kph (50 mph) faster and weighted 370 kg (814 lbs) less, with the same armament.

Over 370 units were delivered to the USAAF prior the V-J Day, too late to see actual combat.

The fastest version of the line, named XP-51 J, was flown in 23 April, 1945 powered by one 1,500 hp. Allison V-1710-119 engine which offered over 1,720 hp. at 6,100 m (20,000 ft) altitude, with water injection and 150 octane fuel.

The prototype weighted 1,432 kg (3,150 lbs) less than the P-51 D-NA and was 87 kph (54 mph) faster.

To save drag the cooling systems were redesigned, with coolant and oil radiators in one ventral fairing. The carburettor intake was also moved to the ventral radiator scoop.

Only two prototypes were built.

On July 1944 the British launched a desperate attack against the new German cruise missiles V-1, to face the 'robot offensive' with their high performance interceptors Mustang Mk.III of RAF Squadrons 129, 306 (Polish) and 313 (Polish).

The aerodynamic drag of the V-1 airframe was higher than anticipated, due to low standards of manufacturing, decreasing from projected 900 km/h (559 mph) to the real 640 km/h (398 mph). Fortunately for the Allies this made the new missile susceptible to be intercepted by conventional fighters, but the game was dangerous.

They used to start the attack with a dive to gain speed, moving on to horizontal flight at 230 m behind the missile to be able to shoot it. The calculation of relative speeds was complicated, and some pilots died when firing from a too short distance.

It was necessary to modify the fighters to make them fast enough to intercept the V-1, the Mustang Mk.III changed their exhaust by those of the Spitfire engine that generated less drag, rear view mirrors and armour plates were also stripped. To reduce the drag on some airplanes, the camouflage paint was removed to gain some speed.

During the 'Operation Diver', between June 1944 and March 1945, sixteen squadrons of interceptors used the new aviation fuel ‘150 grade’ produced in the USA. Using trimethylpentane, that fuel had a higher octane-number, so allowed a higher compression and power output.

Some good data, some a little off based on my sources. Wondering what yours are particularly with respect to GW, flight test comparisons,etc.

For example, the NACA 66, 2(18155) wing was 15.5% T/Cmax compared to 16.13% T/Cmax - true 'thinner' but hardly 'much' thinner, especially since the tip T/Cmax of the H was 12% compared to the 11.46% D wing. At the MAC they were vey close.

Candidly I have not seen a XP-51F vs P-51D flight test but I do have comparisons vs P-51B-5 - both with 1650-3 engines. For the test comparisons I have Vmx delta was 16mph at 31K FTH at 6930#GW for XP-51F @61"MP and P-51B at 8800#GW. Where the XP-51F/G really out performed was in ROC.

EDIT I must have been in a daze because I have no idea why I wrote this "Chilton claimed 491 mph at 6230 GW but I have neither seen the test, nor fullyunderstand how the F without say, 75" boost and minumum fuel - could get there"
AFAIK - no 'official flight test of the XP-51F exceeded 466mph TAS' in level flight. Apologies to HoHun who understandably was vexed by this statement.

My data from Specifications reports has the following empty weight comparisons
XP-51 6280#
XP-51F (still looking for spec number but recall ~5700, with G at 5900)
XP-51J 6030
P-51B 6980
P-51D 7100
P-51H 7040

 

[Foo Fighter]

He was wrong. Although the D was heavier due to increased firepower (2x 50 cal plus 600 rnds of ammo) the fuselage/canopy design with better windshield and flow properties, combined with much better pylon reduced P-51 parasite/form drag co-efficients below the P-51B/C. It was clean enough to offset slight increase in Induced Drag due to 500+ pounds of additional GW,

Long after war, David Lednicer confirmed NAA/NACA 1943-1944 wind tunnel tests with sophisticated CFD/Navier Stokes mesh models to compare the two.

I have both the drag reports as well as the CD build up for both (plus P-51H). The P-51H was the cleanest of all despite being a larger airframe/wing design over the B/D (and F/G/J)

The longer canopy profile as well as the longer aft radiator cooling exit cover were contributors to better aerodynamics to offset the increased profile drag of slightly 'taller' fuselage/canopy section.

Further, the NACA 66 series wing, while basically the same thickness/chord ratio as the NAA/NACA 45-100 wing was slightly less draggy in the low CL range of high speed/cruise

Thanks.

 

[HoHun]

Hi Bill,

Chilton claimed 491 mph at 6230 GW but I have neither seen the test, nor fullyunderstand how the F without say, 75" boost and minumum fuel - could get there

Are we positive that Chilton talked about top level speed and a true air speed figure?

If he was actually talking about 491 mph indicated air speed in a dive, that would be in line with a dive into the region of the P-51D manual's Mach limit, or even beyond it. Validating the diving capabilities of the XP-51F probably would have made good sense too, considering how much of a headache compressiblity could be at the time.

Just my speculative thoughts based on the absence of actual source information!

Regards,

Henning (HoHun)