Vought XF8U-3 Crusader III

[Tailspin Turtle]

JT11/J58 info from Flight, 1959.

http://www.flightglobal.com/pdfarchive/view/1959/1959%20-%200820.html

Thanks, that is very helpful.

 

[shockonlip]

Thanks Overscan for the refs and the pix!

 

[overscan (PaulMM)]

According to Bill Gunston the early J58 engine shown in 1959 was designated JT11A-21.

Also note by 1961 military applications for the engine had disappeared from sight and JT11 was going to be the core of a new SST engine.

http://www.flightglobal.com/pdfarchive/view/1961/1961 - 0994.html

 

[overscan (PaulMM)]

There's a seven page article, J-58/SR-71 Propulsion Integration (or) The Great Adventure into the Technical Unknown by Bill Brown that was published in "Lockheed Horizons", Winter 1981 that seems to be a main source of the J-58 info floating about. An excerpt can be read online here:

http://books.google.com/books?id=sUHuZiBYSKYC&pg=PA225&dq=J58/SR-71+Propulsion+Integration#PPA226,M1

 

[shockonlip]

I always wondered why the prototypes had a 29k J-75 (some sort of oddball that) while the production models would have only had 25k. You'd think they'd have kept the higher powered motor.

...
There were design studies and performance projections with J75s of up to 30,000 lbs thrust supplemented by water injection and/or rocket engines. ... .

Any integration info (airframe/engine) on the rocket engine augmentation?

The piece I quoted yesterday from Rear Admiral Gillcrist, also mentioned rocket augmentation.

Also, are we thinking that a J58 for the F8U-3 might be for just higher thrust levels at
Mach 2.6, or are we thinking that a J58 for the F8U-3 would really be for Mach 3?

Interesting question.

I think I can answer my own question above.
I'm still interested in the rocket augmentation integration question too.

A J58 with or without bypass bleeds may be useful for an airliner or something
that cruises supersonic up to Mach 2.5 (without bypass bleeds) or Mach 3 (with
bypass bleeds), but it won't be useful to a fighter, due to it's low pressure ratio.
When a dogfight progresses to subsonic, it won't have the pressure ratio to give
good performance.

So in my opinion a F8U-3 gets no benefit from a J58 as the J75 is better for subsonic
performance.

So a J58 equipped F8U-3 (dogfighter) never existed.

But maybe it was something else, a J58 equipped XF8U-X/XF9U/X??, which was not a
F8U-3, but something else that flies at Mach 3. Maybe it was a Mach 3 Interceptor
or fast attack aircraft or recce, but not a dogfighter.

 

[Tailspin Turtle]

Any integration info (airframe/engine) on the rocket engine augmentation?

I haven't finished reviewing and summarizing this aspect of the F8U-3, but my initial impression is that the additional acceleration and altitude wasn't worth the hydrogen peroxide storage problem and reduction of range/endurance. It was of interest (like the Mach 3 capability) because of the need to intercept a supersonic Soviet bomber as far away from the carrier as possible. McDonnell also studied a rocket capability for the F4H, apparently as a store on the belly, and Grumman proposed one on the Design 118 that was submitted in competition with Vought's 401 proposal, which was implemented as the F8U-3. (The FJ-4F was reportedly another example, although some reports suggest it was intended as a test bed for an A3J installation.)

 

[sferrin]

I always wondered why the prototypes had a 29k J-75 (some sort of oddball that) while the production models would have only had 25k. You'd think they'd have kept the higher powered motor.

...
There were design studies and performance projections with J75s of up to 30,000 lbs thrust supplemented by water injection and/or rocket engines. ... .

Any integration info (airframe/engine) on the rocket engine augmentation?

The piece I quoted yesterday from Rear Admiral Gillcrist, also mentioned rocket augmentation.

Also, are we thinking that a J58 for the F8U-3 might be for just higher thrust levels at
Mach 2.6, or are we thinking that a J58 for the F8U-3 would really be for Mach 3?

Interesting question.

I think I can answer my own question above.
I'm still interested in the rocket augmentation integration question too.

A J58 with or without bypass bleeds may be useful for an airliner or something
that cruises supersonic up to Mach 2.5 (without bypass bleeds) or Mach 3 (with
bypass bleeds), but it won't be useful to a fighter, due to it's low pressure ratio.
When a dogfight progresses to subsonic, it won't have the pressure ratio to give
good performance.

So in my opinion a F8U-3 gets no benefit from a J58 as the J75 is better for subsonic
performance.

So a J58 equipped F8U-3 (dogfighter) never existed.

But maybe it was something else, a J58 equipped XF8U-X/XF9U/X??, which was not a
F8U-3, but something else that flies at Mach 3. Maybe it was a Mach 3 Interceptor
or fast attack aircraft or recce, but not a dogfighter.

The thing that I've seen many times re: the J-58 is the phrase "originally conceived for a navy attack aircraft" but never is any light shed on what that might be. ???

 

[overscan (PaulMM)]

interesting titbit from 1957

the U.S. Navy have recently been placing an
increasing amount of business with Pratt and Whitney. The com-
pany's largest commitment to the Navy is the J58 turbojet, which is
intended to fill the role for which G.E.'s advanced (high-energy fuel)
engines are being planned for the U.S.A.F.. It has been reported in
the U.S.A. that the J58 is a high-airflow engine intended for operation
at Mach 3 and sized to give 22,500 lb static thrust, conforming to the
Newbury Memorandum requiring each new engine to exceed the
previous generation's output by 50 per cent. Another report, how-
ever, has claimed that the J58 is an 18,000lb engine, which would in
effect make it a much lighter and more advanced unit in the thrust-class
of the J75. Current J58s are designed to use conventional jet fuels,
and their development and testing is being undertaken at the Pratt
and Whitney facility at West Palm Beach, Florida.

http://www.flightglobal.com/pdfarchive/view/1957/1957%20-%201048.html

 

[KJ_Lesnick]

I'm guessing the J-58 lost more thrust at altitude than the J-75?

 

[overscan (PaulMM)]

Erm, based on what exactly?

 

[KJ_Lesnick]

Based on the fact that shockonlip said that the F8U-3 got no benefit out of the J-58 over a J-75.

The J-58 produced more thrust, to the best of my knowledge than a J-75 at sea level, I therefore assumed that at altitude it lost more thrust as it had a lower pressure-ratio.

 

[overscan (PaulMM)]

Wrong. He said

"So in my opinion a F8U-3 gets no benefit from a J58 as the J75 is better for subsonic performance."

A higher compression ratio is more efficient at slower speeds and lower altitudes than a low compression ratio. At high speeds a lower compression ratio is better as it allows you to go faster before the engine gets too hot and/or stalls.

 

[KJ_Lesnick]

Overscan,

Wrong. He said

"So in my opinion a F8U-3 gets no benefit from a J58 as the J75 is better for subsonic performance."

Sorry about that.

A higher compression ratio is more efficient at slower speeds and lower altitudes than a low compression ratio. At high speeds a lower compression ratio is better as it allows you to go faster before the engine gets too hot and/or stalls.

Generally that's the case -- I would not be surprised if the J-58 wasn't as fuel efficient at subsonic speed.


KJ Lesnick

 

[Mark Nankivil]

Greetings All -

A couple of pics from the Vought Archives to give some sense of size and power.....

Enjoy the Day! Mark

 

[overscan (PaulMM)]

Nice photos, and the artwork is especially beautiful.

 

[shockonlip]

I have an engineering paper that I obtained some time ago, about computing
the inlet duct dynamics of the XF8U-3.

The paper is a highly technical, but it does indicate a few historical facts
about the investigations described in the paper. Also the names of Chance Vought
propulsion engineers who were involved with the study are included, and are
possibly still around.

I wouldn't mind helping contact these engineers if you need help as I am very
interested in this subject, but it's up to you.

The paper info follows. I also included the paper's summary and the author
info as well.

Supersonic Inlet Dynamics
H.R. Fraiser
Chance Vought Aircraft, Incorporated
Journal Of The Aero/Space Sciences
June 1960
Pages 429-436

Summary:
An approximation of the differential equation for compressible duct flow is presented.
The equation is linear and of the second order. The duct transfer function and response
characteristics are obtained by applying small-perturbation theory to the differential
equation. The resulting equations describe duct natural frequency as a function of
duct areas and volumes, and damping ratio as a function of the slope of the steady-state
mass flow, pressure-recovery curve.

The calculated response agrees, to a first approximation, with measured response as
obtained from tests of a fixed-geometry, sugar-scoop inlet model with bypass for
matching airflows. Testing was done in the 10 x 10 and 8 x 6 ft. supersonic tunnels at
NASA Lewis Flight Propulsion Laboratory. Further agreement was obtained during flight
tests of the F8U-3 airplane.

The original paper was received by the Journal Of The Aero/Space Sciences on
May 28, 1959. Revised and received November 13, 1959.

H.R. Fraiser is a Propulsion Engineer, Propulsion Group with Chance Vought Aircraft.
The author is also indebted to F.D. Isely and R.D. Witter of Chance Vought Aircraft
for their assistance and guidance throughout this investigation and to Ronald Yoshida
of Marquardt Aircraft Company for suggestions on the method of attack.

(so names of the involved engineers, this Marquardt reference is also quite interesting,
as well as where the testing was done and when the paper was submitted).

Regards.

 

[Tailspin Turtle]

I have an engineering paper that I obtained some time ago, about computing
the inlet duct dynamics of the XF8U-3.

The paper is a highly technical, but it does indicate a few historical facts
about the investigations described in the paper. Also the names of Chance Vought
propulsion engineers who were involved with the study are included, and are
possibly still around.

I wouldn't mind helping contact these engineers if you need help as I am very
interested in this subject, but it's up to you.

The paper info follows. I also included the paper's summary and the author
info as well.

Supersonic Inlet Dynamics
H.R. Fraiser
Chance Vought Aircraft, Incorporated
Journal Of The Aero/Space Sciences
June 1960
Pages 429-436

Summary:
An approximation of the differential equation for compressible duct flow is presented.
The equation is linear and of the second order. The duct transfer function and response
characteristics are obtained by applying small-perturbation theory to the differential
equation. The resulting equations describe duct natural frequency as a function of
duct areas and volumes, and damping ratio as a function of the slope of the steady-state
mass flow, pressure-recovery curve.

The calculated response agrees, to a first approximation, with measured response as
obtained from tests of a fixed-geometry, sugar-scoop inlet model with bypass for
matching airflows. Testing was done in the 10 x 10 and 8 x 6 ft. supersonic tunnels at
NASA Lewis Flight Propulsion Laboratory. Further agreement was obtained during flight
tests of the F8U-3 airplane.

The original paper was received by the Journal Of The Aero/Space Sciences on
May 28, 1959. Revised and received November 13, 1959.

H.R. Fraiser is a Propulsion Engineer, Propulsion Group with Chance Vought Aircraft.
The author is also indebted to F.D. Isely and R.D. Witter of Chance Vought Aircraft
for their assistance and guidance throughout this investigation and to Ronald Yoshida
of Marquardt Aircraft Company for suggestions on the method of attack.

(so names of the involved engineers, this Marquardt reference is also quite interesting,
as well as where the testing was done and when the paper was submitted).

Regards.

Any help you could provide would be welcome. The paper sounds like it might be too technical to be interesting to an enthusiast but the individuals might provide some insight into the change in the inlet rake forward from the proposal/mockup (I've found one NASA test that provides some data on the two different inlet configurations) and the fixes that reduced but did not eliminate compressor stalls in supersonic flight.

Thanks,

T

 

[KJ_Lesnick]

Was the Super-Crusader to carry out hands-off intercepts (or at least heavily automated SAGE style intercepts)? Or was it to carry them out in the conventional style (i.e. carrier vectors them to a given location, they pick up the target with their own radar, fly towards the target, lock up the target, fire on the target, shoot it down, etc)?

Because I remember at the very least some arguments during the development of the XF8U-3 program that two pilots weren't necessary because of a high degree of automation and the pilot would basically be along for the ride. I'm not sure how seriously this was taken or if it was followed through, but at the very least I do remember hearing that Vought did at the very least claim that the single pilot could carry out the workload to perform an intercept.


KJ Lesnick

 

[dreamstar]

Is there any notification when Thomasen's book on the XF8U-3 going to come out?

 

[Tailspin Turtle]

Not soon, since I've been distracted by other things. Perhaps by the end of the year...

 

[SteveDuncan]

http://www.flight-manuals-on-cd.com/ has the Manufacturer's Flight Manual for the F8U-3. It is well worth the price for anyone interested in the Super Crusader and it also has the USN manual for the F-8H and J Crusader.

Some various tidbits from several sources I've run across.

The control stick actually had 2 grips. The right one had the normal aircraft controls and the left controlled the radar. To track a target you used the controller to move a cursor | | over the displayed radar return. That slewed the antenna on to the target which was then automatically tracked within the gimble limits of the dish.

NASA used the Super Crusader for sonic boom tests. Due to the need for precise speeds, the temperature limit of the windscreen (I believe the limiting Mach above 35,000ft due to windscreen temp was something like M2.1) and the fact that the J75 did not have variable reheat, the NASA pilots actually had to fly with the speed brakes extended to keep the aircraft from exceeding Mach 2.

It suffered through various problems with the inlet that were never fully solved. One manifestation of that was that if the afterburner was disengaged above Mach 1.4 the inlet would cause violent engine compressor surges resulting in severe buffeting and loud booms until the speed became subsonic.

 

[circle-5]

Can anyone confirm if that is Chance Vought test pilot John W. Konrad featured in the YouTube video? Thank you.

 

[Abraham Gubler]

The control stick actually had 2 grips. The right one had the normal aircraft controls and the left controlled the radar. To track a target you used the controller to move a cursor | | over the displayed radar return. That slewed the antenna on to the target which was then automatically tracked within the gimble limits of the dish.

This wasn't a unique feature. The Convair F-106 had a twin handle stick.

 

[RyanC]

This could actually be the projected 34" radar version of the XF8U-3.

 

[Stargazer]

The aircraft pictured in that 3-view looks rather strange. The radome, if there is one at all, seems extremely small and would only accommodate a very small diameter radar dish (the nose looks rather more like the one on the radar-less initial versions of the F-8U). The intakes seem to be structurally part of the wing, which would probably preclude a variable-incidence wing (the air ducts would need to be articulated, their AOA would increase with the wing incidence and the actuation system would have more weight and stress to cope with). And if the (small) wing has no variable incidence, where would the low-speed flight characteristics required for a naval aircraft come from, even with sophisticated lift devices or BLC? And why a foreign engine when perfectly suitable US ones were available?

 

[overscan (PaulMM)]

I'm pretty certain it was inspired by a purely verbal description of the XF8U-3 ("ferri intake like an F-105") which was misinterpreted. Like how the unicorn was based on descriptions of a rhino

 

[overscan (PaulMM)]

Merging topics.

 

[Tailspin Turtle]

My F8U-3 monograph got put on the back burner for various reasons but I've been working on it for the last month in hopes of sending the manuscript and illustrations to Steve Ginter by the end of the month. He has other projects in his queue, but was optimistic about producing it early next year. In the meantime, here's a preview of one of the less well known aspects of the program:

 

[Steve Pace]

Does anyone have a good high res color image of the Dash III in-flight?

 

[Mark Nankivil]

Hi Steve -

Hope these fit the bill....

Enjoy the Day! Mark

 

[Rickshaw]

I wonder what the over-the-nose view was like with the F8U-3. Afterall that was one of the major criticisms of the F-111B.

 

[Tailspin Turtle]

I wonder what the over-the-nose view was like with the F8U-3. Afterall that was one of the major criticisms of the F-111B.

It was acceptable. And the view from the F-111B was improved in the production redesign, but it was good enough as is for the carrier trials aboard Coral Sea.

 

[Tailspin Turtle]

Well, thanks to lark, here's the beastie in question.

Chance Vought F9U-1 "Super Crusader"

Rolls-Royce Conway RCo.11 with 7700kgp thrust, 13,600kgp with afterburning, or Rolls-Royce C-133.

Length: 16.6m
Height: 4.5m
Span: 8.4m
Wing area: 20 sq m
Speed: Mach 2.4-2.5
Landing speed: 220km/h
Ceiling: 19800m
Range: 1800km

Flugwelt 1958

Never say never. I found an "investigation" in the files at Vought of a Conway (R.Co.11)-powered F8U-3. Contrary to the fanciful F-105-like three-view provided earlier, the only external difference was the incorporation of a cavity in the belly between the main landing gears for a store. The investigation suggested that it be equipped with all-British systems: avionics, armament, electrical, hydraulic, instruments, etc. I didn't have time to do a complete review of the document. If there was a model number, I missed it. I'll try and take a better look at it next week.

 

[zen]

16.6m? Thats not even 55ft, yet the F8U-III was I seem to reccal 58ft long.

What British systems would it have?

And presumably this is aimed at the RN?

 

[Tailspin Turtle]

16.6m? Thats not even 55ft, yet the F8U-III was I seem to reccal 58ft long.

What British systems would it have?

And presumably this is aimed at the RN?

Only the Conway is specifically mentioned with respect to hardware. Somebody's else's guess will be better than mine with respect to the customer. What Brit requirement was there for a low-level fighter bomber in 1957?

 

[Abraham Gubler]

Only the Conway is specifically mentioned with respect to hardware. Somebody's else's guess will be better than mine with respect to the customer. What Brit requirement was there for a low-level fighter bomber in 1957?

As fighter bomber a replacement for the Scimitar in a new larger carrier. Or in air to air as an alternative to the transonic Sea Vixen?

Does the Conway Crusader (IV?) information have anything about endurance? The lower SFC of the turbofan should provide a bit of a boost.

 

[zen]

How odd.....?

Is this a way of getting a low to medium level fighter after the death in '54 of the Scimitar FAW?

Then again even by 1957 the SeaVixen is hardly a sparkling performer. Knowing this where they already looking to replace it even as it was about to enter service?

The odd thing is the idea of fitting British avionics here, as we know there is no radar/missile combination bar the AI.23/Red Top in this periode. Though there are paper options for the missile.

In theory it has a lot of attractions bar the single engine. It could certainly replace the Scimitar if it can carry the bombload and that high wing could in theory easy the restrictions for carridge of British nuclear weapons (Scimitar essentialy having to land on land rather than the carrier, if returning with Red Beard).

If anything it smacks of the DLI mission, but the Conway suggests they where looking to expand it into the CAP role.

 

[Steve Pace]

XF8U-3 No. 1 in NASA hands - dated 10 September 1959.

 

[Stargazer]

Outstanding pic, Steve, as usual...

 

[Tailspin Turtle]

Only the Conway is specifically mentioned with respect to hardware. Somebody's else's guess will be better than mine with respect to the customer. What Brit requirement was there for a low-level fighter bomber in 1957?

As fighter bomber a replacement for the Scimitar in a new larger carrier. Or in air to air as an alternative to the transonic Sea Vixen?

Does the Conway Crusader (IV?) information have anything about endurance? The lower SFC of the turbofan should provide a bit of a boost.

There was no performance information in the document I found other than the Mach number vs. altitude chart that I posted or any mention of the better sfc presumably provided by the Conway. I suppose that it wasn't the only one provided to the MoD at the time but there's no reference to any others. As usual, I had to put two and two together to get something to say:

In early 1957, Chance Vought and Rolls-Royce teamed up for a “Preliminary Investigation of Possible Manufacture in U.K. of F8U-3 Airframe Incorporating Rolls-Royce Conway Engine,” to present to the British Ministry of Defence (MoD). The license-built F8U-3 was also to incorporate British armament, radar, hydraulic and electrical components, etc. The stated mission was low-level fighter-bomber. It’s possible that the study was being accomplished in anticipation of the British government’s 4 April Defence White Paper, which announced cancellation of most of its advanced manned airplane programs for the Royal Air Force, including the Avro 730 supersonic bomber and the Saunders-Roe SR.177 interceptor. In addition, the Royal Navy did not have a supersonic fighter in development. However, the Scimitar was being introduced and the first production Sea Vixen had just flown in March; neither was affected by the Defense White Paper.

The Conway was an early version of the turbofan engine—and the first to enter service—which incorporated a bigger compressor than required for combustion. The additional air flowed around, or bypassed, the basic engine. This use of additional mass flow provided lower specific fuel consumption than the conventional axial flow jet engine. The Conway engine proposed was R.Co.11, an uprated 17,000-lb thrust version for the improved Victor bomber. With an afterburner added, it would provide thrust equivalent to that of the J75 but with lower fuel consumption.

The document was not, strictly speaking, a proposal. It contained no specific content from the British aerospace industry other than Conway installation details. For example, it states that “A comparable armament system utilizing the present structural attach points for missile pylons, etc. is anticipated for the airplane. This armament system will probably consist in entirety of British items. Installation of such a system is not considered to be particularly difficult.” One interesting omission was any mention of the Martin-Baker ejection seat, which would have one of the most obvious substitutions.

It summarized the F8U-3 design and the changes required to accommodate the Conway engine along with providing structural design and performance data, a raw material list, and high level engineering drawings. The only change besides the Conway was the incorporation of a large recess between the main landing gear for semi-submerged carriage of a 2,000-lb store need for a fighter-bomber mission. The catapult and tail hook were retained. Very little performance data was provided other than level flight speeds. It was projected to have a top speed of Mach 2.2 at 35,000 feet. No mention was made of the presumably lower fuel consumption or any range/endurance benefit.

As it happened, the English Electric Lightning program had been allowed to continue by the MoD as the last manned fighter. The production prototype flew the same day that the White Paper was released. It proved to be an excellent point interceptor, with a terrific rate of climb and Mach 2 speed. While the F8U-3 would have had better range and endurance, its adoption would have involved the budget and schedule penalty of a program startup.

There was no home for it in the Royal Navy either. At the time, the Royal Navy had new, albeit subsonic, airplane programs in progress for all its requirements, with its strike mission to be accomplished by the Blackburn Buccaneer. It also planned to buy the supersonic SR.177, which had been allowed to continue in hopes of a sale to Germany in addition to the small RN purchase. However, at the end of 1957, when the German Defence Ministry announced its short list, the SR.177 was not on it and the program was cancelled.

The British MoD was eventually forced to admit that there was still a need for manned and supersonic strike fighters. Since the development pipeline had been shut off in 1957, it had few alternatives but to order a variation of the eventual winner of the U.S. Navy’s 1958 fighter competition, the F-4 Phantom. Like the F8U-3 Conway proposal, it was powered by a Rolls-Royce turbofan engine, an afterburning variant of its Spey. British airframe and avionics content, however, were limited to the aft fuselage and a radar altimeter.