ATF’s Initial Flight May Be Delayed by Engine Problems
Although the Advanced Tactical Fighter is still in early development, the Air Force is already discussing internally a plan to postpone the first flight of the new jet fighter because parts of the project are going slower than expected, according to knowledgeable industry and military sources.
The potential delays involve development of the ATF’s jet engines, which will feature a new technology known as a “thrust-vectored nozzle.” The nozzle will operate somewhat like a rocket engine in directing the force of engine exhaust, making possible very high-speed maneuvers and short takeoffs.
The schedule delays could push back between three and six months the date of the first flight of the ATF prototypes, which are under development by two prime contractors, Lockheed and Northrop. The original schedule called for the prototypes to make their first test flights in October, 1989. The likely delay would push that into early 1990.
A postponement this early in the ATF program, although embarrassing to the Air Force, may have few long-term consequences. Aerospace experts say that the small delay, if it does not grow into a severe technical obstacle, will not upset the schedule to begin full-scale ATF production in the mid-1990s.
An Air Force spokeswoman said no official decision has been made to delay the ATF program. “The program has not been slipped, but I am not saying it never will be slipped,” she said. “I can’t speculate what is going to happen.”
A briefing paper presented in the Pentagon in recent weeks, however, outlines the probability of a three- to six-month delay in the availability of “flight-qualified” jet engines. The engines are under development at General Electric and Pratt & Whitney.
A resolution of the issue is expected within the next 30 days, the industry sources said. The cost of a three- to six-month schedule delay could not be determined, but it would certainly add millions of dollars to the ATF’s cost if thousands of workers now on the program have to be carried for six additional months.
Since the defense industry has already agreed to develop the ATF at a financial loss under fixed-price contracts, it is not clear who would bear the additional costs.
Aerospace analyst David J. Smith of the Baltimore investment firm of Alex Brown & Sons said rumors of the slippage have circulated in recent weeks. “GE will never be on time,” he said.
ATF prime contractors Northrop and Lockheed have no responsibility for the engines. The Air Force is conducting the engine development separately.
The ATF jet engines are known as the Joint Advanced Fighter Engine (JAFE). General Electric and Pratt & Whitney were each awarded 50-month engine demonstration contracts in September, 1983, worth slightly more than $200 million apiece.
The ATF engines, like much of the program, are highly classified. “We don’t say anything,” a General Electric spokesman said.
One factor that has caused the engine manufacturers problems is that the Air Force had not originally intended to have flying prototypes in the ATF program. The engines were originally to be evaluated and tested on the ground; the additional requirements of providing flight-qualified engines have added substantially to the amount of work.
The ATF engine’s nozzles are one of the major technical hurdles in the ambitious program.
A conventional airplane turns and maneuvers by deflecting air currents moving over control surfaces, such as ailerons, elevators and flaps. A thrust-vectoring nozzle would direct the forward force of the engine much as a firefighter is pushed around by the direction of the fire hose he is holding.
Thrust vectoring would use the power of the engines to force the airplane to turn, climb and dive with very quick responses. It would also enable a pilot to reverse thrust in flight, which would virtually slam on the brakes in a dogfight.
It is believed that thrust vectoring will reduce takeoff distances by up to 35%, an important advantage in determining from which runways the ATF could operate.
