Solar Aircraft Company, San Diego, California

22 November 1948: The Navy Bureau of Aeronautics Representative (BARR) at Ryan was notified that Contract NOa(s) 8203 Items 10, 11, and 12 would have their completion date(s) amended on the contract. The intended new completion date(s) were not included in the Naval Speedletter.

10 December 1948: The BARR followed up on the November progress report with the recommendation that the Navy Bureau of Aeronautics (BuAer) authorize him to accept the Item 5 ABs at 31 – 32% augmentation and permit Solar to proceed with the 70 hour endurance test of the modified units. He further recommended that Solar be authorized to “modernize” one or two of the Navy ABs (these were the four (4) Item 5 deliverable ABs) to verify the contractor’s latest developments in the diffuser section, combustion section and burner design which were expected to provide improved performance. Due to the heavy AB running program, which consisted of two 70 hour endurance tests, one under NOa(s) 8203 and one under a production contract (number not specified), acceptance tests on all production ABs and conduction simulated altitude tests, it was important that there be no delay in moving to the next development phase. The BARR requested that he be advised as expeditiously as possible as to the acceptance of the Navy ABs and the conducting of the 70 hour endurance test.

16 December 1948: BuAer granted authority to the BARR to accept the Item 5 ABs at 31 – 32% augmentation and to conduct the Item 8 70 Hour Endurance Test at that level of augmentation.

28 December 1948: BuAer authorized the use of automatic controls during the 70 Hour endurance test for evaluation and testing. It stated it was not a contract requirement.

31 December 1948: CV asked for $61,137.00 to cover the new work on the Phase III and IV of Contract NOa(s) 9602. These would deliver a high-capacity AB fuel system, ground tests of the XF6U-1 AB, evaluation tests of a new style burner at high boost ratios, and developmental tests of the fuel control and associated controls to be used with the high-capacity fuel system.

5 January 1949: BuAer informed the BARR that since it had been indicated that Solar would be submitting an alternate proposal for further AB development in the near future, the consideration of a further amendment was being temporarily withheld.

12 January 1949: On the production contract for F6U-1s with AB (NOa(s) 8783), BuAer passed on a design change approval procedure to CV. The procedure was to ensure that no changes would be incorporated that would adversely affect the F6U-1 AB performance. All major changes were to follow the procedure. In addition, BuAer asked to be advised when the CV personnel concerned with AB design in the F6U-1 would be transferred from Stratford, CT to their new location in Dallas, TX.

25 January 1949: Solar was asked to proceed with the simulated altitude tests and defer the endurance test pending the decision on their AB modernization proposal.

3 February 1949: BuAer shipped engine X24C4A serial WE002018 to the BARR for use on contracts NOa(s) 8203, NOa(s) 10023 (ABs for the production F6U-1), and NOa(s) 10051 (tailpipes for the XF7U-1 prototypes). Engine WE002020 was to be shipped back to NAMC in Philadelphia and engine WE002024 was to be held for a future assignment.

7 February 1949: Based on their experience with XF6U-1 BuNo. 33532 in the AB testing, CV asked for 200% of the normally projected AB spares be shipped to Dallas to support the flight testing of the production F6U-1 when it started.

14 February 1949: Solar reported to BuAer regarding the difficulty in procuring good N155 tubing for the F6U and F7U AB programs. Almost all deliveries of the material had been rejected due to poor quality. The tubing was failing at the weld line. The tubing was to specification AMS 5532. Four different sizes and a total of 5,797 feet of tubing was required. Anything BuAer could do to expedite delivery would assist in expediting the AB programs.

16 February 1949: BuAer informed the Solar BARR that engine WE002030 was available in El Segundo if needed for the AB contracts and testing.

18 February 1949: CV BARR memo to Aircraft Scheduling Unit, BARR, Wright-Patterson AFB. Solar had reported that Babcock & Wilcox Company felt they could produce seamless tubing if there were a satisfactory market for the material, or if some financial aid were given for developmental work.

18 February 1949: BuAer reported that additional tubing suppliers had been identified. The Bureau had been informally advised that the Stellite Company could produce seamless tubing from their Kokomo, IN plant. No financial support was available at that time.

24 February 1949: Solar asked BuAer to extend the completion date for Amendment No. 9 to 30 June 1949. This was justified by the additional work necessary to complete the amendment.

24 February 1949: The CV BARR reported to Solar that the main problem with the AB tubing was the manufacturing methods being used to form the tubing.

1 March 1949: The addition funds Solar requested to complete Amendment No. 9 were processed on Amendment No. 13.

3 March 1949: Amendment No. 3 was issued to NOa(s) 9602 for CV ground testing. This added clarifying language to the allowable costs for the compensation determination part of the contract.

4 March 1949: A meeting with the Ryan BARR and the CV BARR resulted in fundamental questions being identified as to the method and procedures in the 70 hr qualification tests that required BuAer clarification prior to a firm commitment on this test.

4 March 1949: BuAer asked that a detailed specification of the AB be furnished under their modernized AB proposal. It should be based on the AB to be provided for the F7U-1 using the J34-WE-34 engine. The proposal should state that the AB would satisfactorily pass the 70 hr qualification test. It was assumed the qualification test could be conducted under Item 8 of the contract and that such specification herein requested would not alter the price analysis contained in Solar’s proposal.

6 March 1949 (Estimated): The following AB performance guarantees and expected actual performance for the Solar production ABs were sent to BuAer via telegram. (The information did not include which version of the Solar AB the guarantees applied to, but almost certainly they would apply to the “modernized” version of the Navy's H085000000 Solar had proposed to the Navy on February 25, 1949. A preliminary reply was requested by dispatch on or before 14 March 1949.

On the tag end of the telegram, Solar added that in their letter of 25 February 1948 they should have included the paragraph which was relative to the additional funds required to complete Items 10, 11 and 12. “Amount of request predicated on basis that 70-hour endurance test, Item 8 of Amendment 8, will be eliminated or covered by additional funds.” Solar would make no commitments at that time with respect to the 70-hour qualification test. The matter was to be discussed later in March. Their prior letter on 25 February 1949 did not include funds for the qualification test.

8 March 1949: The Dallas CV BARR relayed a request from CV that the unattached components of the remaining 29 ABs be shipped to CV before delivery of the Solar #472 AB assembly. This would enable subassemblies to be assembled before the main AB assembly arrived.

Fig. 1. Observed Performance with Westinghouse Engine WE002026 During Simulated Altitude Test with Afterburning.

8 March 1949: BuAer clarified an earlier memo from the BARR on 28 February 1949 and stated the ten (10) hour limitation on Military power on AB test stand engines at Solar applied regardless of the AB time associated with it. Whenever the Military time limit was reached prior to the one hundred (100) hour overhaul limit of operation, Solar should submit a detailed breakdown of the operating time on the engine. Simultaneously, they should furnish BuAer information concerning the apparent engine condition and the feasibility of attempting to continue operation until the hundred-hour limit, on either AB or non-AB engine operation.

16 March 1949: BuAer rejected CV’s request of 8 March for the separate delivery of the unattached AB components. They desired that the remaining 29 ABs be acceptance tested as complete units. However, if a limited number of unattached components were necessary from the standpoint of the aircraft (production F6U-1) schedule, the Bureau should be advised.

24 March 1949: Solar Amendment 13 was approved. This covered funding for the roughness investigation of $14,588.12 including the fixed fee.

24 March 1949: Solar requested BuAer authorize, if possible, the supply of a small stock of spare parts to be sent to Solar in support of the three J34s being using in the testing program. The local supply would conceivably save a lot of time while the test program proceeded. A parts list, compiled with the aid of Westinghouse, was attached.

24 March 1949: As requested, CV notified BuAer that the first flights schedule of the first three F6U-1 aircraft would be: BuNo 122478: Not later than 30 May 1949; BuNo 122479: by 15 June 1949; and BuNo 122480: 30 June 1949. The first and fourth F6U-1 ABs and components had been received but no information was on hand regarding additional afterburners. Other complexities were the assumption that Westinghouse was making more emergency fuel systems for the J34-WE-30A engines beyond the two received for the 1st and 4th F6U-1 airplanes. Afterburner components could be installed on those aircraft presently if the components were available. Flights of the fourth aircraft were difficult to predict as the runway at Hensley Field had not yet been lengthened and production flight test operations would have to be conducted from another, yet to be named, location.

28 March 1949: The Dallas BARR recommended approval of CV’s proposed flight AB testing program in the F7U-1 of which 15 hours were in flight and 15 on the ground. CV requested that four Solar ABs with burner ring No. 551 or development thereafter suitable for high boost operation be procured as GFE for use in the tests. Flight testing had been expected to begin as early as mid-March.

31 March 1949: With Solar model 103B ABs installed (but not operated), an X7FU-1 was ferried from Hensley Field to Carswell AFB in TX.

4 April 1949: CV emphasized to BuAer that the airframe completion and flight dates previously communicated were contingent upon receipt of one complete set of afterburner and components by 1 April 1949. As of 4 April, the AB and components had not been received and CV was bringing to BuAer’s attention that a potential delay in the flight date of BuNo 122479 proportionate to the delay in receipt of the subject assembly at their facility was expected.

7 April 1949: NOa(s) 8337 CV was notified that Solar was having difficulties calibrating the AB and obtaining the required thrust. Shipping would be delayed and CV would be further advised later.

15 April 1949: Solar wrote a long memo involving the moving of funds from the NOa(s) 10023 altitude testing to NOa(s) 8203 to cover the cost of the roughness investigation. The amount to be moved was $14,846.76.

18 April 1949: BuAer wrote to Solar confirming the date of the contract NOa(s) 8203 was to be 30 June 1949 but was now informed by Solar that the work would not be complete and another extension would be requested. BuAer asked the BARR to notify them as to whether costs incurred after the delivery date specified should be approved for reimbursement. Pending receipt of the information, invoices for costs subsequent to 30 June 1949 would be withheld.

20 April 1949: BuAer notified CV that their former intention to replace the J34-WE-30A engines in the F6U-1 with J34-WE-34 engines was cancelled. All F6U-1s would retain their J34‑WE-30A engines permanently.

27 April 1949: CV asked for the production F6U-1 to begin flight testing with a +4G flight restriction at 10,500 lb gross weight to allow it to conduct the Part 1 demonstration.

10 May 1949: CV F6U-1 delivery issues regarding ABs. Four ABs had been shipped as of that date with two more to be shipped by 12 May and seven units between 18 and 21 May. Deliveries could be completed by the end of June 1949. Compressor output pressure rakes from Westinghouse had been received, six to date. Further deliveries were to be approximately 20 June 1949. These were required for the MM&M control but Westinghouse thought they were only needed for the experimental Solar testing. The units were being produced under an emergency order from BuAer for the 60 Solar production ABs. Emergency fuel systems for the J34-WE-30A would be shipped beginning 30 June 1949 to supplant the 6 units delivered to date.

23 May 1949: BuAer stated to CV that the Solar A-103B specification weight of 328.6 lb was not yet approved. They asked if the addition of the 5.5 lb of shroud weight was included by using the approved AB weight of 318.6 lb or the unapproved weight of 328.6 lb. CV had earlier (19 May) stated that the recent Solar weight increase did not require additional ballast in the F6U-1 but the aft CG position would now be at the extreme limit and any additional weight would possibly require additional nose ballast.

23 May 1949: XF7U-1 BuNo 122472 made the first recorded flight (76) where an AB was used during the flight. Level at 12,000 ft, the right engine AB switch was moved to the ON position. The AB apparently lit and then cut out before the eyelid “Open” light could come on. Repeated ignition attempts at 11,500, 11,300 and 11,100 rpm resulted in the same sequence of ignition with immediate shutdown before the eyelid “Open” light lit. After the last attempt in the sequence, the eyelid “Closed” light did not come on. The tests were discontinued.

24 May 1949: XF7U-1 BuNo 122472 Flight 77: The right engine AB was turned on in level flight at normal rpm at 12,000 ft and left on for three minutes. The AB control had been set before the flight to regulate the turbine out temperature (TOT) at 550°C. The TOT before turning on the AB was 450°C and was 400°C during the AB run.

28 May 1949: CV responded with the increased AB weight of 5.5 lb for the AB shroud and an approved Solar AB weight of 318.6 lb. The F6U-1 aft CG limit of 32.0% of MAC had been reached and no margin remained for manufacturing variations and heavy engines.

30 May 1949: XF7U-1 BuNo 122472 Flight 79: Installed a new Aerotec switch. The right AB was turned on at 12,000 ft at normal rpm. The TOT was lower than that desired so the engine speed on both engines was increased to 12,000 rpm. The right TOT temperature increased from 410°C to 510°C. A four-minute run was made.

30 May 1949: XF7U-1 BuNo 122472 Flight 80: Fuselage pressures determinations, ABs not used.

30 May 1949: XF7U-1 BuNo 122472 Flight 81: The right AB controls were actuated twice at 12,000 rpm and the left AB controls were actuated twice at 11,500 rpm and 12,000 ft but neither AB lit. Their eyelids opened and the AB fuel flow was normal but there was no increase in thrust and the TOT decreased.

1 June 1949: XF7U-1 BuNo 122472 Flight 82: The right AB turned on at 12,000 and operated for 4 minutes. The TOT reached 510°C indicated. The left AB not operated pending installation of a new pressure switch.

1 June 1949: XF7U-1 BuNo 122472 Flight 83: The right AB was turned on at 12,000 ft. A climb was made at 320 kt to 18,000 ft. The high flow, low altitude AB was expected to blow out between 15,000: 20,000 ft but was still operating at 18,000 ft. The TOT had dropped from 510°C to below 450°C with a noticeable reduction in the rate of climb. The AB climb was stopped and the AB turned off.

1 June 1949: XF7U-1 BuNo 122472 Flight 84: High flow AB run. Installed new Aerotec switch on right side. Rewired the blowout circuit test switch to allow cutout of blowout switch operation. Each AB operated individually for 3 minutes at 12,000 feet using 12,000 rpm. Operation appeared satisfactory with TOTs of approximate 525°C.

1 June 1949: CV complained to the BARR regarding the difficulty in attaching the J34‑WE‑30A engine to the Solar AB in the F6U-1. The attaching flanges on the engine, the exhaust collector, and the AB were not exactly circular, flat, and in one plane. It was taking experienced mechanics 10: 15 minutes to attach the engine to the exhaust collector. The aircraft specification time to remove and replace the engine could not be met. CV suggested that Westinghouse use a longer, conically tapered spigot or that several tapered dowel pins be provided to ensure rapid and proper alignment of the mating parts, thus allowing the clamp to be rapidly installed and secured. (The BARR concurred with CV’s suggestion when forwarding the memo to the Bureau on 10 June 1949.)

2 June 1949: The Dallas BARR asked the Ryan BARR if any ABs for the F6U-1 airplanes had been shipped short of any components and the actual delivery dates for ABs as of 1 June 1949.

2 June 1949: XF7U-1 BuNo 122472 Flight 85: Both ABs were operated together at 12,000 ft using 12,000 rpm for 4 minutes. Maximum thrust was not available due to the setting of the CECO valve limiting AB fuel flow. Except for low turbine out temperatures and a fluctuation of the left engine speed, operation appeared to be satisfactory.

2 June 1949: XF7U-1 BuNo 122472 Flight 86: The CECO valves on both ABs were reset for greater fuel flow. ABs operated in flight separately for 3 minutes each to check out the new CECO valve flow effects. Both ABs ran at 550°C indicated, which was a little low. The airspeed was slower with the right AB running than with the left AB. The engine on the non-operating side was running at approximately 11,000 rpm during the respective run.

3 June 1949: XF7U-1 BuNo 122472 Flight 87: Left AB turned on at 12,000 ft and 12,000 rpm. The TOT that was reset higher before flight appeared to be satisfactory. The right AB was turned on 5 seconds after the left. The right AB went about 50°C above the limit setting, so right AB was shut off after 30 seconds of operation. The right AB reignited at 0.86 indicated Mach just prior to the brown recorder cycle that printed out the TOT. Both ABs were turned off at the end of the brown recording instrument cycle.

3 June 1949: XF7U-1 BuNo 122472 Flight 88: Right AB not operational pending parts arrival. Left AB started at low altitude and climb made to 8,000 ft. During climb, an oscillation of the left engine fuel flow and engine speed occurred that could be felt throughout the aircraft. The oscillation quieted down at 8,000 ft so the AB was ignited and climb made to 12,000 ft. At 12,000 ft an oscillation again picked up so the AB was shut down and the flight terminated.

4 June 1949: XF7U-1 BuNo 122472 Flight 89: Right hand AB fuel amplifier serial #1 replaced with serial #39. The left AB started satisfactorily at 12,000 ft using 12,000 rpm so 5 seconds later the right AB was started. Both appeared to operate satisfactorily as indicated airspeed increased from less than 305 kt to nearly 480 kt over 4 minutes. On AB shutdown, a slight nose up trim change was experienced.

6 June 1949: Contract NOa(s) 9602 - BuAer found a CV license to the government for an AB control switch patent to be unsatisfactory due to the omission of the contractor serial number, title, inventor’s name, and filing date of the patent application with the Patent Office. BuAer asked for the missing data be supplied on their attachment and returned for acceptance.

Fig. 2. AB Pressure Ratio Switch Drawing. CV Patent, 30 June 1948.

6 June 1949: XF7U-1 BuNo 122472 Flight 90: Increased diameter of Aerotec pressure pick up to 1/8 inch at the AB. Both AB blowout circuits wired so that if the switch was too sensitive and shut off the AB before the pressures had stabilized, the pilot could cut out the blowout circuit manually. Both ABs lit at 8,000 ft and a climb made to 19,200 ft. Above 15,000 ft, the TOTs fell off with further increase in altitude as expected for this high flow, low altitude installation. Both ABs were lit at 6,000 ft to check ignition and not allowed to operate for very long.

6 June 1949: XF7U-1 BuNo 122472 Flight 91: Both ABs were lit at 6,000 ft and a climb made to 20,000 ft. Above 15,000 ft, the TOTs fell off with altitude as expected with the low altitude, high flow burner rings. The ABs did not blow out in the climb, but were shut down by the pilot at 20,000 ft. Both ABs were ignited at 16,000 ft. The right burner fuel flow and engine speed varied slowly over a range of 300 units (lb/hr, rpm).

6 June 1949: XF7U-1 BuNo 122472 Flight 92: The switches that cut out the blowout circuit to actuate the AB fuel solenoid valves were rewired. This made possible the check of the Aerotec blowout circuit section by simulating a blowout. When the fuel was cut, the switch should automatically close the eyelids, shut off the AB pump and return the boost pumps to normal operation. During flight, the ABs were operated separately. The left AB was lit successfully at 6,000, 11,000, 15,000 and 18,700 ft. The fuel was shut off and the switch operated successfully following each of four starts at 7,700, 12,000, 16,000 and 19,200 ft. The left AB ignited successfully after a several second pause but cut out immediately at 20,000 ft. The right AB lit at 8,000, 13,000 and 17,000 ft. The Aerotec switch operated successfully at 9,500, 14,000 and 18,000 ft. It failed to start once at 17,000 ft prior to successful ignition. Prior estimates had predicted poor or no operation above 15,000 ft for the high flow, low altitude burners were then installed.

A run was made at 12,000 ft but a low amplitude, rapid variation of the left engine fuel flow and engine speed of 12,000 rpm could be felt through the aircraft so the left engine was not started. The right AB was started but a variation of fuel flow and engine speed occurred so after about 2 minutes of recording, the AB was shut down by simulating blowout. Simulated blowouts in climbs resulted in an increase in engine speed of less than 400 rpm prior to eyelid closing, but an increase of 700 rpm was obtained on the right engine in a higher ram level flight run at 12,000 ft.

9 June 1949: CV was asked to advise on the effects on the F6U-1 airplane of lowering the AB operating limits to the newly updated Solar A-103B specifications. This had added a dead band region at airspeeds below 380 kt above altitudes from 33,500 to 40,000 ft. CV had responded that the best climb of the F6U-1 was above 380 kt at 40,000 ft which was outside the dead band. Maneuvering and allowing the airspeed to decrease below 380 kt would result in AB blowout and force a descent because of insufficient thrust available to sustain level flight. That would also apply to climbs where the airspeed decayed below 380 kt. CV stated that the restrictions, while undesirable, were not entirely unacceptable. They urged every effort be made to remove the restrictions.

9 June 1949: XF7U-1 BuNo 122472 Flight 93: Repaired right hand AB burner ring cracks. Installed 4 pressure survey tubes through the upper skin in AB compartment on right hand side. Installed pressure tube for survey through right hand tailpipe diaphragm between hook compartment and the AB shroud. Changed CECO valve #31 and replaced it with #14 on right hand side. Adjusted both CECO valves. Increased right hand eyelid closed diameter by 0.10". The left AB was turned on at 5,000 ft. Operation appeared satisfactory except for usual one or two second delay before the eyelids opened. Reduction of engine speed was apparent prior to opening occurring, then returning to within 210 rpm of original setting. The right AB was turned on about 15 seconds after the left with a similar eyelid delay being experienced. A climb was made to 24,000 ft. The right TOT was a little high. Neither TOT fell off above 15,000 as they had on previous flights due to the higher CECO valve settings. At 23,000 ft the left AB apparently blew out as would be expected with the high flow, low altitude burner rings.

10 June 1949: XF7U-1 BuNo 122472 Flight 94: The left AB was started at 3,800 ft and after a 30 second stabilized run, the blowout circuit checked by turning off the AB fuel solenoid valve. The overspeed was about 300 rpm. The right AB was ignited at 2,700 ft and after a 30 second run the blowout circuit was checked in the same method as the left. The overspeed was 700 rpm but the ram was also higher.

14 June 1949: XF7U-1 BuNo 122472 Flight 95: The left AB was used during takeoff, the engine running at 12,000 rpm. The right engine was operated dry at 12,500 rpm. The TOT on the left engine was satisfactorily controlled. The right turbine TOT indicated low for takeoff and fell off in the climb to 15,000 ft. The directional trim due to asymmetrical power was not very noticeable.

14 June 1949: Solar issued Engineering Order No. 32808 to affect ABs installed in the F6U-1. It called for a 40 micron fuel filter to be installed between the AB fuel pump and the Chandler Evans fuel metering valve to protect the close tolerance parts of the AB fuel controls. A filter meeting the specification was not commercially available and would have to be specially procured. Some modification of fuel lines in the airframe would be necessary, the type and extent to be determined by the size of the procured filter. Solar projected an estimated cost to procure and purchase sufficient quantities for the F6U-1 program would be $3,200.00

15 June 1949: Solar Contract NOa(s) 8203 Amendment No. 13 issued. This shifted funds of $16,495.00 from endurance testing to the Item 13 roughness investigation and added $14,846.76 to fully fund the Item 13 cost and fixed fee.

18 June 1949: XF7U-1 BuNo 122472 Flight 96: Purpose of the flight was high flow AB climbs. Four AB starts, two on each engine and six minutes of AB time, three on each AB, were logged during two climbs. New engine and accessories checked and various other adjustments as well during the flight.

21 June 1949: XF7U-1 BuNo 122472 Flight 97: Both ABs turned on prior to takeoff. A takeoff and climb followed by a short level run at 14,000 ft was made using 4.5 minutes of AB operation on both engines at 12,000 rpm. The TOTs on pilot’s instrument panel were 10°C lower with the ABs on at 12,000 rpm than with the eyelids closed at 12,500 rpm. The left TOT held fairly constant during the AB climb but the right TOT fell off a little over 10°C indicating a low setting of the CECO valve.

22 June 1949: XF7U-1 BuNo 122472 Flight 98: Both ABs turned on prior to takeoff and operated for 5 minutes. The IAS increased to 390 kt at 2,000 ft prior to climbing to 15,000 ft where a short level run was made. The indicated TOTs on the ground were 580/590°C L/R engines at 12,500 rpm. At 15,000 ft at 12,000 rpm, ABs on, they were 540°C both the L/R engines. The left AB was checked for operation at 2,000 ft and 305 kt and appeared satisfactory. Both ABs were turned off using the blow out circuit check switches at 15,000 ft. The engine speed increase was less than 500 rpm during the blow out checks.

23 June 1949: XF7U-1 BuNo 122472 Flight 99: AB takeoff made, both running. Climbed to 11,500 ft, cloud limited height. Run made up to 480 kt (0.87 IMN) (Indicated Mach Number). TOTs observed - Ground AB off 575°C L/R; AB on prior to T/O 590°C left, 600°C right; at 7,000 ft 570°C both L/R; at 10,000 ft; at 11,500 ft 546°C left and 510°C right. Both ABs ignited again at 2,000 ft and 310 kt IAS. Operation satisfactory except for slight delay in the ignition of the right AB.

23 June 1949: Solar advised the BARR that a Solar representative was available and awaited an assignment from BuAer at Dallas.

24 June 1949: The Dallas BARR asked for urgent overhaul of the J34-WE-22 engines being used for Contract NOa(s) 8337 AB ground testing. If rapid turnaround time for the overhaul was not possible, they requested permission to use one or more production engines scheduled for the F7U-1 program in the interim.

29 June 1949: F6U-1 BuNo 122478 Flight 1: Improper operation of the A/C unit allowed hot air to blow on pilot’s feet and flight was terminated immediately after takeoff. Shot hops prior to flight showed satisfactory performance and control. AB not used.

1 July 1949: F6U-1 BuNo 122478 Flight 2: Flight satisfactory. AB not used.

5 July 1949: F6U-1 BuNo 122478 Flight 6: Performance check. Slow acceleration noted in level flight at 10,000 ft. A possible cause was that the AB eyelids were creeping open; this was to be investigated.

7 July 1949: F6U-1 BuNo 122478 Flight 7: Prior to flight, AB shroud replaced with part from No. 3 aircraft and a crack welded in the AB. Tightened the eyelids to close an additional 0.1” distance across the eyelids in the closed position. AB not used.

9 July 1949: F6U-1 BuNo 122478 Flight 10: The eyelids were opened in flight and the engine speed increased from 120 to 270 rpm at the higher rpm settings. Upon closing the eyelids, the rpms remained elevated and did not return to the original setting. On landing the eyelids were opened to reduce idling thrust and decrease the landing run.

11 July 1949: XF7U-1 BuNo 122472 Flight 101: Before flight removed Solar Hi-flow low altitude AB #102 on right side and replaced it with Solar Model 551 AB #106. Removed Solar Hi-flow low altitude AB #100 of left side and replaced it with Solar Model 551 AB #103. Replaced defective left- and right-hand fuel shutoff switches on the pilot’s console. Removed Aerotec #1 and replaced it with #51 on the left side. Decreased nozzle diameters on both engines by 0.30”. After takeoff, runs were made to check the new installations of the model 551 low flow ABs. The ABs were ignited at 8,000 ft and shut off at 15,000 ft. Operation appeared to be satisfactory. Engine overspeed was held to 150 left and 99 rpm right by the flyball governors after shutdown.

15 July 1949: BuAer notified the BARR at CV that Solar required the 40 micron filter. They asked the Ryan Barr to send a description of the proposed filter to them and to CV for an evaluation. A further explanation to the BARR noted that Solar had found that small shavings from pump parts emanated from gear pumps regardless of the cleanliness of the fuel admitted to the fuel inlet. The metal shavings could cause malfunction of the RC-3 pressure operated valve which would cause a severe under or over pressure thrust when the AB was operating.

18 July 1949: CV Part 1 Power Plant Demonstration Model XF7U-1 Airplane: In the appendix to the main report, CV discussed the fact that the difference in thrust between the engines with a straight tailpipe installed and those when a Solar AB system was installed was about 150 lb of thrust per engine. This was an 8% decrease in thrust. Calculations for temperature and altitude adjustments were presented showing that the "thrust velocity lapse rate is adversely affected by the Solar afterburner of the order of 8 – 11% at a Mach Number of 0.73."

27 July 1949: CV reported experiencing “explosions” on engine start on both the XF7U-1 and F6U-1. This was a recent development and investigation had found the engines were undamaged. It was thought to be caused by the pilot leaving the throttle slightly open before the engine start, allowing excess fuel to accumulate and forming an explosive mixture which ignited when the engine start began. CV thought the addition of the longer tailpipes and/or ABs were preventing natural ventilation from removing the explosive mixture prior to the start. Running the starter for 15 seconds with the fuel off was found to remove any residual fumes prior to start with fuel turned back on. A modification to the starter switch to add a 15 second delay was recommended.

30 July 1949: XF7U-1 BuNo 122472 Flight 107: Purpose of the flight was to attempt AB starts with the lo-flow, 551 burner, Solar ABs. At 10,000 ft the ABs were turned on at 12,000 rpm and 261 kt IAS. The right AB did not start and the left started and blew out almost immediately. Both ABs started and then blew out after approximately 2 seconds of operation at 11,500 ft, 12,000 rpm and 330 kt IAS.

Fig. 4. Solar Breadboard AB Control System Next to Altitude Test Rig

5 August 1949: F6U-1 BuNo 122478 Flight 19: Afterburner Climb. In a climb at 12,000 ft, started the AB and continued to 20,600 ft where the AB blew out. Not clear if the flame blew out or the Aerotec switch shut it off. The AB was not a full thrust as the CECO and MM&M valves were adjusted for lower fuel flow. The TOT and AB fuel flow were both low.

8 August 1949: XF7U-1 BuNo 122472 Flight 108: Before flight, the CECO valves were replaced on both ABs, the shrouds and tail cone supports were replaced on both ABs. The fuel valve manual switches for the ABs were disconnected and the Aerotec switch was connected for blowout protection. Several unsuccessful attempts were made to light the ABs at 12,000 ft. Several more attempts were made at engine speeds from 12,000 to 12,500 rpm. In all cases, the left AB fuel flow remained zero and the eyelids remained closed. The right AB would give a slight starting kick, have fuel flow and the eyelids open light would go on, but the TOT would decrease and there was no thrust increase. It was assumed the Aerotec switch would have shut off the fuel flow and closed the eyelids if the Aerotec switch had been energized.

10 August 1949: F6U-1 BuNo 122478 Flight 20: AB climb and Carbon Dioxide/Carbon Monoxide Demonstration (which oxide was not specified). Replaced MM&M control valve. Adjusted CECO fuel control valve for higher fuel flow. Opened the P1, P2, P3 air tech eyelid pressure switch pickup holes in AB from 1/16” to 1/8” diameter. Before takeoff, a successful AB start was made. Military takeoff without AB was made to 10,000 ft altitude. At 12,000 ft, a successful AB start was made at 12,500 rpm at 255 kt IAS. A Combat power climb was made at combat power (12,500 rpm plus AB) to 25,400 ft. No evidence of engine surge was encountered, but the longitudinal pulsation previously encountered was experienced during the climb. AB operation was satisfactory.

10 August 1949: XF7U-1 BuNo 122472 Flight 109: Afterburner Climb. The left AB did not start at 8,000 ft due to the sticking of the solenoid fuel valve. The right AB ignited satisfactorily and the TOT held fairly constant at 590°C to 19,000 when it was shut down.

11 August 1949: XF7U-1 BuNo 122472 Flight 110: Test fuselage pressures with AB ON. Lit both ABs at 6,000 ft in a Military power climb. Power was on for 3.5 minutes up to 12,000 ft and a level speed run up to 0.89M was made. Rough air made the AB fuel flow fluctuate in the cockpit, but the later investigation showed the ABs were not affected but the cockpit instrumentation was.

12 August 1949: F6U-1 BuNo 122478 Flight 22: Rewired cockpit switch to AB blow out circuit, readjusted CECO switch clockwise 1/8 turn. A normal takeoff and climb to 15,000 ft were made. Six (6) AB starts were attained at 12,500 rpm and 258 kt IAS for starting. Starts obtained with the blowout protection circuit in or out were similar. Data was obtained for analysis.

12 August 1949: XF7U-1 BuNo 122472 Flight 111: AB starts were checked at 4,000 and 15,000 ft. An AB climb was made from 4,000 to 25,000 ft. The left AB started OK at 4,000 ft. The right AB started but ran for a few seconds with low AB fuel flow and low TOT before beginning normal operation. After reaching 0.68M, a climb to 25,000 ft was commenced with the speed increasing to 0.75M. Both ABs blew out (or were cut off) at 25,000 ft. The Aerotec switch had been deactivated on the right engine only before the climb but both ABs blew out within seconds of each other. A slow oscillation of the right engine speed was observed at reduced powers where governor surge was reported in the F6U-1. The oscillation was mild and went away after 3 or 4 cycles. No AB roughness was felt.

16 August 1949: F6U-1 BuNo 122478 Flight 23: Combat power at 12,500 rpm and AB operating. Two AB starts at 12,000 ft and 257 kt IAS were made. The AB blew out after 10-12 seconds each time. Prior to the blowout, the rpm and TOT were both decreasing. The eyelids remained open after blowout because the Aerotec switch was de-energized until the AB control switch was placed at OFF. A decent was made to 10,000 ft and a satisfactory AB start was made at 12,500 rpm and 285 kt IAS. A climb was made to 21,500 ft where the AB blew out. The rpm stabilized at 12,360 rpm during the climb. The TOT was constant at 595-600°C during the climb. AB operation was deemed satisfactory except for a longitudinal pulsation which occurred only when the AB was operating.

16 August 1949: F6U-1 BuNo 122478 Flight 23: Flight to determine the maximum altitude at which the AB would not ignite. Constant climb with starts and shutdowns using a constant airspeed. Initial start at 6,000 ft at 285 kt IAS using 12,450 rpm. Over 7 attempted starts, as soon as stable operation was “assured” the AB was shut down and restarted shortly thereafter at roughly similar IAS and rpm. The maximum altitude a start was attained was 14,700 ft but burning could not be sustained because of rough running and falling rpm after the start.

18 August 1949: XF7U-1 BuNo 122472 Flight 112: Reconnected Aerotec switches in the cockpit. Maximum AB altitude test flight. ABs turned on at 2,000 ft and 260 kt IAS. Several attempts to start the right AB were made before it lit successfully. It would light and immediately blow out. The fuel flow would drop to zero and the eyelids close. With both ABs running, the climb commenced at 375 kt at 5,000 ft, speed dropping off at rate of 5 kt per thousand feet throughout the climb. Twice during the climb the engine speed dropped off 200-300 rpm with the right hand engine dropping off slightly more than the left. Throttle adjustment kept the rpm at 12,500 rpm. Throttle creep might have caused the drop but that was not definitely determined. The TOT temps rose from 580°C to 600°C. At 23,000 ft both ABs blew out. The eyelids closed and fuel flow dropped to zero automatically. During the decent, the ABs were started at 12,000 ft and 347 kt IAS. The left started normally. The right started with low fuel flow and a low TOT of 500°C with rough burning. As speed increased to 410 kt, fuel flow and TOT rose to their normal readings along with smooth burning. Further AB starts were made at 2,000 ft and 175 kt IAS. The left started, the right did not. Fuel flow on it was low and the eyelids did not open.

19 August 1949: XF7U-1 BuNo 122472 Flight 113: AB starts and simulated blowout check. Before flight, the left hand AB eyelid lights were checked and also both the left and right hand AB ignition. The ABs were started at 2,000 ft, 225 kt IAS and 12,500 rpm. The emergency fuel shut-off valve was then turned to OFF to simulate AB blowout. The blowout system closed the eyelids.

20 August 1949: XF7U-1 BuNo 122472 Flight 114: An AB takeoff and climb to 14,000 ft was made. The climbing speed was below the best speed for climb below 8,000 ft. This was the first flight using model 551 burner rings in the ABs. TOTs regulated around 600°C during the entire operation. No AB issues.

22 August 1949: XF7U-1 BuNo 122472 Flight 115: An AB takeoff was made. Held below 2,000 ft until the indicated Mach number of 0.65 was reached, a climb was made to 14,000 ft to an indicated Mach number of 0.89 was reached. TOTs regulated around 600°C during the entire operation. No AB issues.

22 August 1949: XF7U-1 BuNo 122472 Flight 116: AB takeoff made after ABs had stabilized. Climb made to 10,000 ft and speed increased to 0.88M. TOTs were comparatively low at end of the run. Two attempts were necessary to get the left AB to start before takeoff.

22 August 1949: XF7U-1 BuNo 122472 Flight 117: AB takeoff made after starting the ABs separately before brake release. Speed was built to 480 kt below 1,500 ft and a climb commenced. TOTs and rpm remained constant at 600°C and 12,500 throughout the climb. At 26,500 ft the TOT on right engine dropped rapidly followed by blowout at 27,000 ft. The fuel flow dropped to zero and the eyelids closed. The sequence repeated immediately on the left engine.

23 August 1949: XF7U-1 BuNo 122472 Flight 118: Took off and lit ABs at 1,500 ft after a decent from 6,000 ft. Starts were at 390 kt IAS at 12,500 rpm, beginning with the left AB. The airspeed was built up to 490 kt IAS and a climb commenced, speed decreasing 5 kt per 1,000 ft altitude gained. Time to climb to 20,000 ft at best climbing speed was less than two minutes. In level flight at 20,000 ft, a run was made using 12,500 rpm. The indicated Mach number of 0.89 (calculated 0.905) and 410 kt was attained. ABs were turned off after 5 minutes 45 seconds of continuous operation. On descent, AB starting was attempted at 14,000 ft and 347 kt using 12,500 rpm. The left started and immediately blew out on second attempt. The right did not start on two attempts.

24 August 1949: XF7U-1 BuNo 122472 Flight 118: ABs started separately before takeoff had begun. Accelerated to 44 kt at 1,500 ft and climb begun. Climb schedule was 5 kt of decreasing IAS for each 1,000 ft to 10,000. TOTs and rpm held constant at 600°C and 12,500 rpm. Level run to 0.89 indicated Mach number made. AB time was approximately 6 minutes. AB starts were attempted at 174, 217 and 260 kt IAS. Left did not start at lowest and middle airspeed, but did start at the higher. Right started at lowest and intermediate speed but with rough running before operation became normal. Start of highest speed was normal.