The early work by Westinghouse on the axial turbojet models 19A, 19B and its successor the 19XB-2B never included any discussion of adding reheat, tail-pipe burning or afterburning (AB) as it is known now. The early engines’ low thrusts and the performance of the McDonnell FD-1 with its J30 engines showed both the limitations of low thrust and reduced range because of high fuel consumption, but also the promise of higher speeds when more thrust became available. The idling thrust of the J30 in the FD-1 added to the difficulty in slowing the aircraft down for carrier landings and a mockup of a thrust diverter for the J30 was built but never constructed or tested. [Early Westinghouse Axial Turbojets 19A, 19B, 19XB-2B (J30), 9.5A/B (J32) Page 227, by the author.]

Fig.1. 19XB-2B Thrust Diverter Design Mockup. WAGT P33013, 5/3/1944. Courtesy of the Hagley Museum and Library.

6 March 1944: The U. S. Navy Bureau of Aeronautics (BuAer) issued a requirement to Westinghouse for an engine of 3,000 lb of thrust and a lower specific fuel consumption than the earlier models. This would emerge as the J34 in the Westinghouse (WAGT) response of April 20, 1944 as the model 23C. The “23” indicated the diameter of the engine in inches. The specification was for a booster engine and did not provide for AB support in any form. The overall design was unambitious and carried over a pressure ratio of 4:1 from the early designs. It would use a ten-stage axial compressor, two stage turbine, ball and roller bearings with engine lubrication using oil mist (similar to the very small J32) and achieve a specific fuel consumption (SFC) of 1.07 lb/hr/lb. Air flow would be 54.5 lb/sec at 12,000 rpm. Early design changes included enlarging the diameter of the combustion chamber to 24"; the WAGT model then becoming the 24C from that point forward. The engine’s prolonged development would add complexity to the various airframe manufacturers’ efforts to bring airframes to production status. The many delays and design changes to the development J34 engines also complicated the parallel efforts of Ryan, Solar and McDonnell to develop ABs that were intended to be able to be attached to the back of production J34 engines. Those airframe development histories were related in the earlier segments of this series on early Navy AB development. [The full J34 development story can be found in the author’s Westinghouse J34 Axial Turbojet Family, Development History and Technical Profiles.)

1 August, 1945: WAGT responded to a request from BuAer under Contract NOa(s) 3962 with proposal AGT-6 specifying adjustable nozzles for the 19XB and X24C-4. It included development to be complete and three fully tested variable nozzles for each model to be delivered by 1 April 1946. Development would continue with the view to making the nozzles fully automatic.

12 September 1945: BuAer rejected the 1 August proposal for the reasons of it failing to deliver a fully automatic nozzle along with production and testing of four complete nozzles (for each model) prior to delivery. They stated that manually controlled nozzles were OK until the automatic control was added later. The testing acceptance should include designs for full service usage and the passing of any qualification test and operating schedule to which the engine might be subjected.

April 1946: BuAer asked WAGT for a tail-pipe burning system proposal for the X24C engines. The variable exhaust nozzle should be integrated with this proposal as the AB would require such a nozzle anyway.

10 June 1946: WAGT’s AB proposal (AGTD-25) for a cost plus fixed price of $476,632.00 would deliver four ABs plus various design reports. The design would include the variable nozzle. The AB would attach to the exhaust extension flange of the X24C-4B without alteration and use a special type of automatic variable area exhaust nozzle operated from a single lever pilot control. Delivery would be two ABs in 18 months and two more 19 months after contract acceptance. The acceptance test would be by the Bureau Air Resident Representative (BARR) in Essington; the test run would consist of an X24C‑4B engine without alternation and the AB operation not to exceed fifteen minutes in total duration but sufficient to the demonstrate to the BARR that the guarantees were met.

BuAer failed to accept the proposal at that time. WAGT continued to develop the X24C-4B without an AB to get it through an acceptance test.

Pre-production engine design changes: During early development many changes had been made, the greatest being the addition of another compressor stage to the X24C-2 and changing the lubrication system in the middle of the development pre-production run of the model 24C‑4. This divided the run into -4A and -4B engines, the latter having “solid” oil lubrication in place of the earlier oil mist design. The -4B engine led to the first production engine model, a design produced as the J34‑WE‑22 engine. Initial production started in Essington, Pennsylvania while a new factory was outfitted and staff trained in Kansas City, Missouri to produce the very large numbers of the J34 engines that were expected to be needed by both the U.S. Navy and the U.S Air Force. The J34‑WE-22 still did not have any design elements in it to support an AB even though Ryan and Solar’s work had shown changes to the aft flange of the exhaust nozzle would need to be made to make it stronger to enable ABs to be attached. The production engine also did not have any circuits and controls for an AB as part of the engine control. A thrust diverter design was built for the 24C-4 model engines and tested. No details other than the picture (Fig. 2) were found.

Fig. 2. 24C-4 Thrust Diverter Mounted in Test Cell. WAGT P35997, 11/8/1946. Courtesy of the Hagley Museum and Library.

31 January 1947: In dialog with BuAer about the planned use of the 24C-4B production version engine in the Lockheed XP-90, WAGT stated they had no contract for AB development. They had done some work on design, construction, and very preliminary functional testing of a conservative test stand model that was not suitable for flight, but at that point all work on AB development had stopped. The test AB had a maximum burner temperature of 3,000°F and was expected to produce a thrust augmentation of 40-45% under sea-level conditions. Further development was expected to increase the burner temperature and static augmentation percentage.

15 October 1947: Another WAGT proposal for an AB development was sent to BuAer (AGT-34 – not found).

8 December 1947: BuAer responded to the proposal, saying they understood that the J34-WE-22 would need modifications to operate with an AB. These would include an automatic integrated control and might include structural revision of the turbine housing and rear flange of the basic engine to enable AB attachment. Such modifications should not affect installation interchangeability with any engines already produced. BuAer asked if WAGT could proceed with full scale engine and component testing under contract NOa(s) 5382 (J34-WE-22 production) under Section “B”, “Supporting Services”. Production could not be affected in any way and no money or time in addition to those authorized under Contract NOa(s) 5382 could be expended.

All available data from Solar, Ryan and McDonnell AB development programs would be provided to WAGT. If acceptable to WAGT as described, the BARR was authorized to approve test projects in accordance with a program agreed upon between BuAer and WAGT.

19 January 1948: WAGT notified BuAer that production J34-WE-22 engines beginning with Serial No. WE020121 would have a 0.125" combustion chamber housing rear flange. All engines with prior serial numbers should be allocated to non-AB projects.

24 May 1948: BuAer accepted WAGT’s development plan, reminding WAGT that any components developed would be the property of the U.S. Navy (versus the Air Force) when the contract was completed. If funding was extended beyond 30 June 1948 and WAGT was willing to continue development, the components would be reallocated to them for use in further work.

25 May 1948: WAGT asked for BuAer assistance in getting their prototype AB tested in the NACA wind tunnel along with the Ryan and Solar tests then planned.

11 June 1948: BuAer responded saying the AB testing in Cleveland was being curtailed beginning 1 July 1948 because of higher priorities. As of that date, only Solar and Ryan ABs had been tested. While it was not possible to know when testing might continue, both the WAGT and McDonnell ABs would be put on the schedule.

11 June 1948: BuAer asked for the date that a Specification for the planned AB under development would be available.

18 June 1948: WAGT was informed that under a new Supplemental National Defense Appropriation Act, Public Law 547, the availability for the expenditure of the required funds had been extended to 30 June 1949.

1 September 1948: Specification WAGT-X24C5-2 was issued (not found) for the AB and four reports were being prepared. These were contingent on the F-80 flight test installation results. The F-80 installation was being delayed due to unspecified problems. (The reports mentioned were not delivered to BuAer until 5 January 1949, but since they included the development details of and testing history of the early AB test models, the data from these reports are inserted here to allow the reader to follow the AB development in some semblance of chronological order.)

Fig. 9. WAGT Experimental Model 1 AB Layout. The Model 1A differed in not having a liner, which resulted in increased thrust because of the higher temperature operation possible.	Fig. 10. Model 1 Flame Holder for the 24C-4B Based on Work at the Massachusetts Institute of Technology.

Model 1 testing showed that the durability of most parts was satisfactory during 80 minutes of wet operation and 626 minutes dry. The AB started consistently from 10,000 to 12,000 rpm and occasionally up to 12,500 rpm when a 306 in² nozzle was used. Vibrations were not noted except at shutdown. Squeal was heard when the fuel was shut off, the sound likened to that of tires during an emergency stop. At that point, the cause was unknown. Combustion efficiency was between 90 – 100% and wall cooling problems were not encountered. The four-foot cooling length was found to be undesirable. The design required very good pressure recovery in the AB diffuser thus requiring that part to be very long. Too much attention to burning efficiency had been paid at the expense of length, weight, pressure loss, and structure. The Model 2 had a shorter burner length and simple, sturdy flameholder with less blocking of the air flow and a shorter diffuser.

1 November 1948: WAGT copied BuAer with the specification above and referenced Contract NOa(s) 9670 (for the J34-WE-32, -38 and J46-WE-2), stating they wished to continue AB development under that contract.

11 November 1948: Progress Report A-770 covering Project 839, the control system for the AB.

[Author's Note: Text below taken from Westinghouse J34 Axial Turbojet Family, Development History and Technical Profiles, Chapter 9.]

After initial studies were complete, it was determined the development should progress toward automatic scheduling of an optimum fuel/air ratio in the AB while maintaining the peak turbine temperature by modulation on an infinitely variable exhaust nozzle while providing the pilot a means to establish the desired percentage of thrust augmentation by manual selection of fuel routing to the afterburner fuel manifolds. (Note: If achieved, it would give the pilot some level of variable AB thrust, not just an on/off option. – Auth.)

It was decided to develop a fuel system that could maintain a given fuel pressure for a given measure of mass air flow, thus keeping the AB fuel/air ratio within the limits of stable burning over the anticipated flight conditions for partial as well as full augmentation. A parallel development of an automatic engine exhaust nozzle was underway, so Project 839 focused on a manually controlled electric actuator to the exhaust nozzle to be used on the first development AB. The work was completed on schedule and formed the groundwork for the detailed design of the fully automatic systems for the J34-WE-32 and J46 afterburners.

As developed for the initial prototype, the engine power control only held the Military rpm of the engine and peak turbine outlet temperature at constant values through coordinated regulation of engine fuel and modulation of the exhaust nozzle area, irrespective of any variations in AB operating conditions. The exhaust nozzle area was adjusted by the pilot in accordance with temperature indications on a cockpit instrument. The control used a toggle switch operating an electric actuator linked directly to the exhaust nozzle eyelids. This would later be replaced by a hydraulic exhaust nozzle actuator eliminating the need for the separate cockpit control.

It was found to be necessary to arrange for admission of fuel to the afterburner in progressive steps starting with the innermost manifold and then all the manifolds for full thrust. Fuel pressure rather than fuel flow was scheduled in the fuel regulator to avoid complexity. The result was the ability to cut out groups of fuel nozzles without upsetting the local fuel/air ratios in the afterburner. In the prototype, the AB control system was provided with a fuel pressure regulator which automatically maintained the manually-selected fuel pressure settings irrespective of the degree of thrust augmentation selected. A separate fuel source next to the spark plug was found to be unnecessary. The continuously operating ignition coils proved capable of maintaining a continuous spark during the entire period of afterburner operation.

Available air-turbine driven fuel pumps were not adequate without modifications. Special engine driven gear type pumps of 13,000 lb/hr capacity were provided for the first two J34 development ABs.

It was determined it would be possible to use the planned J34-WE-32 and J46 power controls interchangeably on AB and non-AB burning engine variants. Further development would be concentrated on the AB fuel regular and afterburner fuel pump in Project 962.

Fig. 11. J34-WE-11 AB Fuel Control Schematic. WAGT Report A-770. Courtesy Hagley Museum and Library	Fig. 12. XJ34-WE-11 AB Specification Thrust Chart; Assumes J34-WE-22 Engine Used.

13 December 1948: The various performance and thrust curves for the engine specification were submitted to BuAer. The basic engine at that time was to be a production J34-WE-22 and the sea level thrust with the AB installed dry was reduced from 3,000 to 2,900 lb (-3.3%) but with the AB wet the thrust was 4,100 lb (+41.3%). With work on the XJ34-WE-32 engine and its afterburner underway, the Air Force designated XJ34-WE-11 model can be seen as an intermediate stepping stone to meeting the full BuAer requirements for the XJ34-WE-32.

10 January 1949: Delivery of the final report, A-795, covering AB durability. (Report not found.)

20 January 1949: Report A-796 Contract NOa(s) 9670 included the information that eight “production” ABs were under construction with the first to be completed by 4 February 1949. Two were to be assigned to the 24C8 (J34-WE-32) program development testing and the balance to be shipped to the XF-90 flight test program.

25 January 1949: The Air Forced asked that the engine’s continuous power operating limit be raised from 15 to 30 minutes for the XF-80A-2 test program. WAGT approved the increase and also increased the continuous operating limit time on the AB from 5 to 10 minutes. BuAer also approved. These extensions were intended to allow the project flight tests to reach higher altitudes and obtain complete equilibrium of flight variables which suggested they only be used when necessary.

Although the J34-WE-22 was only qualified with a 15-minute Military test time limit, such an extension of the continuous military time had been granted to the Douglas D-558-II project and such extended operation was not considered hazardous by WAGT when accomplished at medium and high altitudes.

18 March 1949: BuAer finally responded to WAGT’s 12 January memo. They noted that although some detail objectives of the program had not been achieved, the balance of the work reported was all within the scope of the contractor’s outline. However, the reports made no mention of the overall objective quoted in their 8 December 1947 proposal. Apparently, all the efforts had been devoted to design and construction of a workable AB system specifically toward immediate application in the F-80 and XF-90 airplanes and also the contract NOa(s) 9670 afterburner development. BuAer requested that a report summarizing the degree of attainment of the overall objectives be submitted in addition to the reports already submitted and the specification WAGT-X24C5-2 written under the program.

The general description contained in the proposal regarding the type of afterburner control system actually developed for the F-80 and XF-90 airplanes was not sufficient to enable BuAer to determine whether or not that system was superior to the Solar ABs in use in the F6U-1 and XF7U-1 airplanes. A detailed description of the XF-90 control system was requested before the earlier request for two sets of the developed control systems could be reconsidered. “Until acceptable information requested (above) is presented, transfer of afterburner and associated engine modification materials from contract NOa(s) 5362 to contract NOa(s) 9670, as requested, is not authorized.” As will be seen a bit later, many changes to the design of the J34-WE-32 AB control came about at this time as responses to the -32’s mock up board suggestions were worked through.

29 June 1949: Issue of Report A-864 – Afterburner Fuel Control Development Contract NOa(s) 5382. The report included a schematic sketch of the control system that met the requirements of an automatic control system permitting selection of partial augmentation by the pilot, the latter having been demonstrated in flight tests. It was felt it lent itself more readily than any other known type to adaptation to future engine models with electronic governing system (planned for the J34-WE-32, -38, J46 and J40 engines) to provide maximum thrust augmentation with maximum combustion efficiencies.

Fig. 17. AB Fuel Control Schematic as Used in the XF-90 Flight Test Program.

For the XJ34-WE-32 program, the manual fuel pressure regulator was replaced with an automatic barostatic device. The -32 design would also include an emergency system to route fuel from the main engine fuel pump in case of failure of the AB fuel pump or fuel pressure control elements.

The report included a comparison to the Solar fuel control system. It stated its main drawback was that at higher altitudes, increasing amounts of fuel were required to achieve a given temperature rise and consequently the fuel consumption might increase out of proportion to the additional thrust obtained.

To meet condition No. 1, mass air flow through the engine had a linear relationship with the compressor outlet total pressure, which considered air speed, temperature and altitude. Outlet pressure was selected as the basis for scheduling fuel to the AB.

To meet condition No. 2, an infinitely variable-area tail was believed necessary, utilizing the fuel control to maintain optimum fuel/air ratios. It would provide the maximum range of operating conditions and maximum combustion efficiency, both the basic engine and the AB. It was noted that the performance guarantees for all the new engine designs under development for BuAer were based on the utilization of an infinitely variable exhaust nozzle for the basic engine.

To meet condition No. 3, fuel flow by means of pressure regulation was necessary. Thus, as any desired portion of the total number of manifolds was selected, the proper fuel/air ratio for the manifolds still operating could be maintained automatically.

Based on the above, WAGT felt that their control system best met the requirements for an AB with a variable-area exhaust nozzle where partial thrust augmentation was desired.

10 August 1949: BuAer acknowledged receipt of the reports, reminding WAGT that they had suggested the basic engine control be revised to provide a fully automatic engine-AB control along with full protection against exceeding the safe operating limits of the basic engine at all times.

21 October 1949: WAGT forwarded to BuAer a memo on modifications needed by the J34-WE-22 in an effort to resolve the impasse and gain the Power Plant Division’s approval. Attached were copies of the Specification WAGT-X24C5-2A dated August 26, 1949 and copies of five drawings (not retained).

27 October 1949: The BARR’s forwarding memo added some further details. The 4-hour endurance test had actually been done as a development project under Contract NOa(s) 9670. The BARR was not informed of the start of the test and the defects resulting from the test were not on display for the BARR to review. (This was an Air Force Project.) The WAGT XJ34-WE-11 engines supplied to the Air Force had considerable trouble in that the flameholders, diffuser struts and the eyelid seal had cracked during the acceptance test. Thrust in both non-AB and AB operation had been borderline to the guarantees. SFCs were about 10% below the guarantees.

14 December 1949: BuAer HQ accepted the information received as answering the open questions and considered the objectives of the program as having been generally met. Transfer of residual AB and associated components to NOa(s) 9670 as GFE was authorized. A list of the items transferred was requested.

16 December 1949: In a USAF memo covering the Model XF-90 Flight Test Progress Report 14, it was stated that the XF-90 used the J34-WE-22 engines WE020016 and WE020019 modified with WAGT ABs to the J34-WE-11 configuration. The engines ran reliably for the most part in limited flying but Lockheed discovered the basic engine thrust with the AB attached but not operating dropped 14%. Phase I testing was forced to use the North Field at Muroc due to extremely wet conditions on the lake bed. To attain acceptable takeoff conditions on the shorter North Field airstrip, the ABs were removed and JATO bottles used to supply the missing thrust. WAGT engineers installed improved seals around the AB eyelids and the ABs were reinstalled for the Phase II testing. Total Phase I and Phase II flying time was about 40 – 50 hours across both airframes.

27 January 1950: The list, which shows two (2) complete AB assemblies and a variety of modified engine parts, was delivered to the BARR on January 27, 1950.

At this point, all development attention was now on the other Westinghouse contracts that were to use ABs. These were the J34-WE-32, the J46-WE-2 and the J40-WE-8/22 and their complex and intertwined development histories will be covered next.