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Link to: “Testing the Republic F-84 Thunderjet" - Part Two Editor's Note: We know the Thunderjet as the F-84 but in 1947 we still used the "P" (pursuit) designation seen in this article. The museum has both an early straight wing version and a later swept wing version of the F-84. TESTING THE THUNDERJET LATEST JET FIGHTER TO JOIN AAF OPERATIONS PUT THROUGH ITS PACES BY REPUBLIC’S TEST PILOT Editor’s note: Photographs which illustrate this article were specially taken by Martin & Kelman. In order not to interfere with Republic Aviation Corporation’s important program of service testing these aircraft, an entire week was required to take the photos which are reproduced here. That is why different numbers appear on the P-84s of these pages. Basically they are all put through the same testing routine.
You can’t keep thinking at the rate of 400 miles per hour when you re flying 600 mph. That’s the first lesson to learn when the time comes for a company test pilot to hurdle the gap between conventional reciprocating engine fighter planes and the new jet-propelled ‘‘squirt jobs.’’ We used to think we were really high-tailing it in the days when we climbed into the cockpit of the old T’bolts, as the P-47’s became affectionately known in every combat theater around the world. And as we went through all the experimental tests and, later, the regular acceptance flights with the Thunderbolt, we got to know her like an old friend. We knew all the fancies and the foibles of this seven-ton concentration of horsepower, until the tricks of getting every last ounce of performance out of her became pretty much routine. At Farmingdale, Long Island, and at Evansville, Indiana, Republic put together 15,329 of these babies, and you can judge by that the fact that the company’s test pilots never had too much time to sit around the lounge and engage in “hangar flying” except when the weather closed in on us and forced us to leave our coveralls and our goggles hanging up in the locker while we flew with our hands in describing some new characteristic we had uncovered in the previous day’s tests. At that, we sometimes came closer to disaster getting our arms all tied up in unflyable attitudes while we were relating the latest maneuvers than we did in actually executing the maneuver in the airplane. Every airplane driver has his own ideas and methods of doing flight tests. At the same time, when a group of pilots are working on the same type of ship, they keep close tabs on each other in order to extract the experiences of everyone in putting planes through their paces. There is no such thing as a secret formula. By the same token, the test pilot learns all he can about a new airplane long before he even climbs into it for his cockpit check. From the time it moves from the drawing board to the production line, he is asking questions of engineers, aerodynamicists, stress analysts, weight engineers, and project men. He practically lives with the flight test engineer assigned to the airplane, because this man is possessed of all the technical knowledge and theory concerned with that particular airplane.
Strictly speaking, it is no longer fashionable to climb into a new type of aircraft and take it up for a ride to determine whether it will fly or will execute a certain type of maneuver without falling apart. The aeronautical sciences have progressed to the point where it is determined long before flight just what is likely to occur in the air. In the case of the P-84 Thunderjet, for example, the Army Air Forces called for a jet fighter with certain characteristics and performance qualities. Republic’s engineers, under Alexander Kartveli, vice- president in charge of engineering, put down on paper a design which they felt would meet those requirements two full years before the first prototype was ready for flight. The design was based on certain factors exclusive of the plane itself. For instance, the plane was built to house an engine which also was on paper at that time. If the General Electric engineers and production men did their job in producing a powerplant with the guaranteed amount of thrust, our engineers and production men were betting that the Thunderjet would meet all performance guarantees plus or minus one or two percent. If you think that’s as easy as it looks on paper, please remember that in this particular case, the airplane under consideration was being planned as the fastest hunk of machinery this country had ever produced—planned to fly in the area of 600 miles per hour!
In order to keep this long story from being even longer, let’s just say that the AAF Air Materiel Command, which is responsible for the development and procurement of all Army aircraft, flew the airplane and was satisfied with its performance to such a degree that procurement contracts were immediately signed and Generals Eaker and Powers have since stated that the P-84 Thunderjet is the standard fighter airplane on order for the next fiscal year. There is also the little matter of a world speed record—but that’s another story, except to say that we hope that Republic’s present planning with the AAF will result in raising the mark by enough miles per hour so that the United States will be able to hold onto it for some time to come.
Flight-testing the Thunderjet has been the responsibility of a handful of us, since the airplane was first taken to Muroc Army Air Base for its initial bow. Wally Lein, now with North American, was the first man to leave the ground in the ‘84. Lowery Brabham, now head of Republic’s Military Contracts department, but then Director of Flight, took time off from his first flights with the four-engine XF-12 Rainbow to get valuable information on Thunderjet flight characteristics first hand. Oscar Hass, now Director of Flight, also spends a certain amount of time away from his XF-12 testing and his important desk work, investigating P-84 performance. Jack Bade and I do the balance of the flitting about over Long Island wringing out the bugs.
There is a lot of difference between experimental or service flight testing now, and the kind we engaged in while the war was on. And it’s not all just the difference between the types of planes then and now. It involves greatly reduced rates of procurement and production; varying methods of modifications and improvements, and a lot of other less tangible differences between wartime and peace time development. In 1942, when the first P47’s came off the line, it was well understood they would be used for training and not for combat; therefore, changes not involving combat performance could easily be held off while the production line rolled on and rates of manufacture were being established. In the event any of those first hundred or so ships were as signed to overseas use, they could be brought back and the necessary changes made. That saved valuable time and was one of the reasons why this country was able to expand its aircraft industry so rapidly into all-out production.
But, today, every airplane coming off the line must, theoretically, be able to do the job for which it is assigned and on short notice. Everything in the ship must work immediately—guns, instruments, special fuel tanks, and, of course, the airplane itself—according to the strictest performance requirements. This is not because the AAF expects they will have to be used in combat, but because procurement, production, training, recruitment and all the other elements of maintaining the best air force under restricted circumstances of the economy have to be geared to getting the most done with what is available under present budget requirements. For that reason, it will take far longer to equip and retain a strong air force, providing it with the most modern aircraft that research and development can produce than it did during the war years. Those are some of the philosophical differences. Now for some of the actual technical differences........(continued in part Two) |
