J57 derivatives for F-101

[bigron427]

Good evening!

I am working on a book about the F-101 Voodoo, and have some questions about different engines tested during development. I am specifically interested in details about the J57-P-53 engines that powered early production blocks of the F-101B, as well as P-23 and P-45 versions that I know were tested on the P&W aircraft, 53-2426, but have no other details.

I am also looking for information on problems encountered with integrating the J57 with the F-101, and how these problems were overcome.

Thanks in advance!

Ron Easley

 

[bigron427]

Wow, has it really been a year since I posted this? :

I have continued scratching away at this so am posting what scant results are available for anyone interested.

The F-101B was approved in mid-1955, to be powered by advanced derivatives of the basic J57 engine. The primary track for engine development was undertaken by Pratt & Whitney. The ninth preproduction F-101A, 53-2426, was bailed to P&W and delivered to their facility at Edwards AFB on 22 Octiber 1955. At the time the aircraft was delivered, it retained its original J57-P-13 engines as well at they Type II inlet ducts that represented McDonnell's first attempt at addressing the compressor surge in the F-101A, which was quite severe with the original design. The engines would surge at full power settings immediately after takeoff or in any accelerated manuever over 1.5 G.

53-2426 was to be used for flight testing of advanced J57s for the F-101B, but at the time it was delivered the F-101A was still experiencing compressor surge. Indeed, throughout 1955 this was considered the major potential operational deficiency in the aircraft. While MAC continued work on refining both the inlet design and the geometry of the ducts leading to the engines, P&W initially concentrated on the powerplant to increase the surge boundary. The fixes to the basic engine proceded fairly quickly, although it took a great deal of time and effort on MAC's part to address the inlet duct issues. By December 1955, the surge boundary of the J57 had been improved to the point that, unbeknownst to pilots or MAC engineers alike, the F-101A began to run into the pitch-up boundary. Within a span of a few weeks from late December 1955 through mid-January 1956, Robet Little had enocuntered pitch-up at supersonic speed but recovered, Capt. John Dolan pitched up and rode in an F-101A near Edwards AFB, and Maj. Lonnie Moore pitched up on takeoff at Eglin AFB. As it turned out, there was little warning up through about Mach 0.95, and no warning whatsoever at supersonic speeds.

Initially, the F-101B was designed for the J57-P-45 engine, with the J57-P-35 as an interim fit. I have no evidence that the J57-P-35 was ever built or flown. Somewhere around early 1956, 53-2426 received the first of the developed engines, installed in the right engine bay. I have been unable to turn up specific records, but by all appearances this was the J57-P-45 engine. It looks as though it had a variable-flap ejector nozzle and, at least from P&W sources, was the first ever convergent-divergent turdojet nozzle flown and capable of producing over 17,000 pounds of thrust apiece. Unfortunately, I have no hard dates or other records to confirm this information, which is based on the recollections of a P&W test pilot. Apparently, at the time the news of the Fairey F.D.2 breaking the speed record reached the folks at Edwards, 53-2426 had been retrofitted with two C/D engines and during tests by P&W was routinely flying at speeds approaching Mach 2. Again, the record so far is extremely spotty but given G.E.'s experience with the variable ejector nozzle of the J79 in its early years, it is not surprising that this was abandoned for a fixed C/D nozzle design, the 57-P-55. This is what was flown on Project Firewall by Maj. Adrian Drew in December 1957, using P&W's development aircraft.

In the meantime, MAC was conducting its own tests using 53-2429 to test improved inlet ducts with a higher critical Mach number, the Type III inlet duct. By this time, a different interim engine for the F-101B was developed and flight tesgted on this aircraft by taking the existing J57-P-13 engine and modifying it with the afterburner developed for the J57-P-23 engine slated for prodcution examples of the F-102A. This yielded the J57-P-53 engine, tested on JF-101A 53-2426 and produced for F-101B aircraft 1-15 (not counting the NF-101A, 56-232.) These aircraft were built with a Type IIIb inlet that had been optimized for the J57-P-45 engine, but proved to be oversized for the production J57-P-55, leading to a slight but significant performance penatly for the F-101B. The inlet duct was simplified for more cost-efficient production to yield the Type IIIc, which is what was installed on most F-101B aircraft. As far as I can tell, both MAC and the USAF had decided to cut their developmental losses by this point and chose not to optimize the duct for the production "Dash-55" engine.

Anyway, for anyone interested, this is what I have come up with so far. I am thinking about a trip early next year to go through the P&W archives at the New England Air Museum to try to find more information.

 

[shockonlip]

Thanks Ron!

I'm a Voodoo fan myself!

Keep digging!

I wonder how high in thrust the J57 eventually got to?

Did McDonnell ever investigate a J75 engined example?

 

[bigron427]

JFC Fuller,

I first heard specifically of C/D nozzle tests on 53-2426 about a year and a half ago, and a few months leter saw a photo of the aircraft. It wasn' the "Dash-55" engine that I am familiar with. A bit after that, I ran across a book on P&W engines by Jack Connors (excellent overview!) where the J57-P-45 was listed in a table. Earlier this year, I received a bunch of contract documents and official correspondence from Paul Stevens and found references to both the "Dash-35" and "Dash-45" engines so I have at least that much documentation, but no hard dates or technical information as of yet. The fixed C/D nozzle design of the J57-P-55 engines used in prodcution F-101B aircraft were sufficient to raise the thrust from 16,000 lbs. with the P-53 to 16,900 pounds. Taking some measurements from an F-101B, the exhaust velocity for the P-55 engine works out to about Mach 1.3 assuming ideal gas flow. (For reference, the throat diameter is about 32 inches, the exhaust diameter 34 inches to give an Ae/At ratio of about 1.13.) The same basic afterburner nozzle was used in the later versions of the F-8, equipped with J57-P-16 and J57-P-20 engines. The design was relatively heavy and could only be optimized for one set of conditions, but it was robust, effective, and sufficient to get both the F-101 and F-8 out to very close to Mach 2, and this with non-adjustable inlets.

I'm not sure that there was much of any consideration of optimizing the engines for low altitude for the F-101. Given the nightmare scenario that the USAF, MAC and P&W went through just to successfully integrate the J57 engine with the airframe and have it work within the aircraft's operational parameters, I think that it would have pretty much amounted to reinventing the wheel, if you will. By July 1957 when the F-101A and RF-101A began to enter service with TAC, the strategic fighter version had been curtailed in favor of more recce airframes. At least until the need for a true low-level capability was shown after the Cuban Missile Crisis, the RF-101 was intended mainly for use at medium and high altitudes where it could take best advantage of its speed and large-format KA-1 cameras. From TAC's perspective, it was placing all of its bets on the F-105 which could be better tailored to changes in mission or doctrine as it was still under development. Once the J57-P-13 engine and Type IIb inlets eliminated compressor surge through the speed and maneuvering envelope of the F-101A, there were no further changes to the engine, at least to those assigned to a "tactical" mission.

Ron Easley
Aerospace Museum of California
Sacramento, CA

 

[bigron427]

Shockonlip:

Yeah, this airplane has some fascinating stories attached to it. You might search the Post-War Jets thread for "F-101" to see some of the earlier stuff I posted on weapons.

As far as engines go, the J57-P-55 with 16,900 lbs. thrust was the most powerful used in the Voodoo. The F-8 had a longer production run and took advantage of further developments of the engine. Looking at the table in Connors, the F8U-2 (F-8C) used the J57-P-16 engine with a C/D nozzle producing 16,900 lbs in A/B. This was roughly contemporaneous with the J57-P-55 of the F-101B. As manufactured, the F-8D and F-8E used the J57-P-20 from about late 1959, producing 18,000 lbs. in A/B. Remanufactured F-8H and F-8J models used the J57-P-420 from about 1967, with a maximum thrust rating of 19,600 lbs. in A/B. As far as I can tell, there were no changes to the basic afterburner design but my guess is that they found ways to increase the engine compression ration as they continued to refine the J57 design. While normal rated power remained about the same, there was a corresponding increase in available military power in the later versions.

The J75 was considered for use with developed versions of the McDonnel Model 36 but due to their larger diameter would have required extensive redesign. J79s, however, were strongly considered. If you want more specific information on the J75 proposals for the Voodoo, let me know and I will look them up.

 

[bigron427]

A thumbnail sketch for Voodoo engine options, beginning with the XF-88, follows (dates listed if available):

Model 36C (XF-88): 2 x J34-WE-22
Model 36D (XF-88A): 2 x J34-WE-15 (with MAC-designed A/B)
Model 36E: 2 x J33-A-23
Model 36F: 2 x J46-WE-2 (Intended production version of F-88)
Model 36N: 2 x Allison J71
Model 36S: 2 x G.E. J73
Model 36V: 2 x J67 (F-88J, leter resurected as the "Voodoo 67" for which I have some performance figures)
Model 36W: 2 x J57 (F-88K, renamed F-101A and granted contract)
Models 36AE-1 through 36AE-4: J67 (three of the versions), XJ-79 (one version). Sometime prior to May 1954 (no date)
Model 36AK: SAC fighter derivative of F-101A with 2 x J75-P-1 with 20-inch constant section added, two more fuel cells, and duct/nacelle changes. (6 May 1954)
Model 36AT: 2 x J57-P-55 (F-101B, 22 Nov 1954) Also provision for rocket boost pod.
Model 36AU: Advanced variant of F-101A with 2 x Allison J71 (15 Dec 1954)
Model 36BE: F-101B with J79-GE-3 (8 Jul 1955).
Model 36BF: F-101B with nacelle changes for J57-P-35, J57-P-49 (15 Jul 1955).
Model 36BJ: F-101B with J57-P-45 (steel or titanium case, 27 Oct 1955).

The Curtiss-Wright J67-W-1 remained a very strong contender for the F-101 through its cancellation in mid-1955. As this audience knows, it was an Americanized Bristol Olympus engine that offered similar specific fuel consumption to the J57, better surge characteristics, and higher thrust. This higher thrust would have led to decreased range and combat radius, but the thrust-to-weight ratio would have been extremely impressive! One wonders what would have become of this engine if C-W had its act together from a company management standpoint.

From early 1956 on, the various design proposals considered either the J57-P-55 or various versions of the G.E. J79, most notably the J79-GE-7 in the later studies. The J79 was flown in the Number One F-101A, 53-2418, from November 1956 but by this point with more advanced designs on the horizon, re-engined versions were not seriously considered for production. The engines in this aircraft were later modified to burn borane fuel in the afterburner to provide data for the development of the J93-GE-5 engine for the B-70. It first flew with these engines in September 1958. I know that Steve Pace posts here and would like to discuss this further with him sometime, as I first leaned about this in his B-70 book a number of years ago.

 

[Stargazer]

Did McDonnell ever investigate a J75 engined example?

If I refer to McDonnell's own internal models list, the Voodoo was mostly studied in J57 and J79 variants. A handful of J67-powered were also considered. As for the J75, I was able to find three projects, as shown in attachment:

 

[bigron427]

Well, almost another year has passed...time to add an update!

In recent weeks, I have been trying to pin down who flew the first flight using a turbojet with an engine with a convergent-divergent nozzle. GE flew its F4D, Bu. No. 124587, on 8 December 1955. However, flying with a YJ79-GE-3 engine producing only 13,500 lbs in AB (versus 14,700 for the following modified "Dash-3" engine), I question whether it had a functioning divergent ejector nozzle for its first flight, although a C-D nozzle was integral to the design of the J79.

Pratt & Whitney's F-101A, 53-2426, flew with a J57 with a variable C-D nozzle at about the same time, although I have yet to pin down a date. I have seen one photo that I will post later, and had assumed that it was the J57-P-45 engine. However, doing some reading on the F-107 today I saw reference to the J57-P-35, which had been proposed earlier. It had been the original proposed engine for the F-107 before Mach 2 became the design goal and emphasis switched to the J67 and J75. My guesstimate is that development work on the new C-D engine started at the beginning of 1954. Using the J57-P-35 engine producing 17,200 lbs in AB, the early version of the F-107 design was supposed to reach Mach 1.7. Dropped from consideration in mid-June 1955, a month later the engine found its way into a MAC proposal for the Model 36BF interceptor derivative.

Pratt & Whitney received its F-101A on 20 October 1955 and soon went to work on the Voodoo's severe compressor stall problem, giving P&W the data they needed to tweak the surge boundary of the engine compressors while MAC worked out the inlet ducts. This went fairly quickly, after which they received the first of two "long can" engines for flight testing. I wonder if it was the J57-P-35 that they tested. Two years after starting on it, they might have had some flyable hardware by the end of 1955. I'd kill for a proper identification of the engine flown as well as some good dates! ;D

 

[sferrin]

Did McDonnell ever investigate a J75 engined example?

If I refer to McDonnell's own internal models list, the Voodoo was mostly studied in J57 and J79 variants. A handful of J67-powered were also considered. As for the J75, I was able to find three projects, as shown in attachment:

An F-101 with a pair of J-75s would have been something to see.

 

[charleybarley]

bigron,
I'm sure you already have this book but, in case not, there are some general CD nozzle F-101 test flying accounts by P&W's Harry Schmidt and McDonnell's Robert Little. Nothing detailed with respect to engine ID or dates though. The CD nozzle was also variously referred to as the "long afterburner" and the "supersonic nozzle" by these pilots. Harry Schmidt's account does say that the CD on the J75 and the CD on the J79 in an F-104 came after the F-101 flights - no dates tho.
Also much testing was done with only one "supersonic afterburner" for several months before the second one was installed.
"Test Pilot" edited by Harry Schmidt