The F136,is being designed to be installationally interchangeable with the F135, and also to respond in precisely the same way to all interfaces between engine and pilot so that in theory a future F-35 pilot would not know which type of engine was installed in his aircraft.

VAATE is the national turbine engine technology plan that will provide the future propulsion capability our war fighters need to combat these changing threats to our security. Comprised of all sectors of the Department of Defense, NASA, the Department of Energy, six major engine companies and three airframe manufacturers, VAATE is a totally integrated, physics-based, turbine engine technology program chaired by the Office of the Secretary of Defense. The program includes technical activities, which will improve turbine engine capabilities beyond those of a year 2000 baseline engine while reducing all facets of engine cost.

GE F136
40,490lb MAX
26,090lb MIL

PW F135
43,000lb MAX
28,000lb MAX

"The F136,is being designed to be installationally interchangeable with the F135, and also to respond in precisely the same way to all interfaces between engine and pilot so that in theory a future F-35 pilot would not know which type of engine was installed in his aircraft."

According to "Jane's" here are some given performance ratings



GE's site for the F136 says "Thrust Range: 40,000 lbs."
PW's site for the F135 says "Thrust: 40,000 lb"

Like the PW-229 and the GE-129 they are probably VERY close; IE "29,000
lb Class"

Since..


I doubt there would be a BIG difference in thrust or the pilot may notice?

Funny, I was under the impression that the GE F-136 made much more power than the P&W F-135???

Yeah, GE would like everyone to believe that they have something "superior" to offer. The reality, however, is quite different.

When GE developed the F110 for the F-16, they were able to convince the USAF to allow them to change the rules of the game in their favor. Rather than attempting to precisely match the F100 on a size and thrust basis, they convinced the USAF to increase the inlet area for the GE-equipped airplane, which allowed them to produce more thrust than the F100-220 that was then in production without having to attain the greater hot section temperatures. The result has been that the GE and P&W engines are NOT interchangeable. With the exception of experimental airframes, you cannot plug one engine into the other's airframe. P&W meanwhile, elected to develop a higher thrust version of its engine, the F100-229 that maintained maximum commonality with its F100-220 predecessor - and could fit into the same engine bay.

The Air Force today is determined not to let this two-track engine approach (which was forced upon them by Congress) derail their airframe and logistical planning for JSF. They have insisted that both P&W and GE fit into the same engine bay, and use the same amount of airflow to meet the USAF thrust requirements. This means that GE can't play the same game of developing a cooler engine with more airflow that they can market as being somehow "superior" to the original engine requirement. Both P&W and GE are going to have to operate to nearly the same hot section temperature to meet minimal thrust demands for the F-35 - a real problem for GE since P&W has more experience operating at these temperatures.

The F136 has a long way to go to achieve even parity with the F135. P&W has been flying the basic core for their engine in the F-22 for over a decade now. I fully expect the price tag for GE to come up that learning curve to be far in excess of what has been quoted to Congress and the US Air Force. They have a lot of catching up to do - and their partnership with their ally/rival Rolls Royce (which is producing the fan and LPT for the F136) is only going to complicate matters.

Well, that is a very good point and I understand what you are saying. That said, during the development of the YF-22. Didn't the GE YF-120 generate more power than the P&W YF-119? Which, both designs matured into todays GE F-136 and P&W F-135..............

Well, that is a very good point and I understand what you are saying. That said, during the development of the YF-22. Didn't the GE YF-120 generate more power than the P&W YF-119? Which, both designs matured into todays GE F-136 and P&W F-135..............

Sounds like the F-35 Program is benefiting from the competition between P & W (F-135) and GE (F-136)!

I would agree that the F-35 is benefiting from the "Great Engine War" between the F100 and F110. That episode has left a lasting impression in the industry, where no one takes their success for granted any longer.

I fail to see the "benefit", however, from the F135/F136 competition. The US is being asked to foot the bill to develop TWO entirely different engines. This is a giant aerospace welfare project, fueled by Congressional delegates whose districts would benefit from more GE engine sales, and by our British allies who would prefer to see the US produce an engine with more Rolls Royce content.

Contrary to popular misperception, the US military does not purchase these engines in a traditional "free market" environment, where competitors have an incentive to lower their cost to win more market share. Quite the opposite. The US government insists that would-be suppliers must open their books to government review, demonstrate how much it really costs to make their product, and are then allowed to earn a profit at a pre-set rate. The cost of the F135 and F136 will be fixed by the manufacturing cost for each engine - not the amount of profit margin that the suppliers might WISH they could earn. The government will decide how much profit the suppliers can make.

So instead of buying more F-22s or F-35s, we are instead developing a "competitor" engine that will do nothing to lower costs. It's pork barrel politics, as usual.

is it really in the interests of the US Goverment to give one manufature the vast majority of the fighter engine market for many decades to come?

I am not so sure I agree..............is it really in the interests of the US Goverment to give one manufature the vast majority of the fighter engine market for many decades to come? While, it may be more expensive. The advantages clearly out way the cost.............IMO

Is it really in the interests of the US Government to give one manufacturer the vast majority of the bomber engine market for many decades to come? GE was the sole source supplier for jet engines for the B-1 and B-2, and more recently won a US government contract under the ADVENT program (Adaptive Versatile Engine Technology), that is expected to be a pre-cursor to America's next bomber engine. Pratt & Whitney lost out on that competition. Does that make sense?

The bottom line is that neither GE nor Pratt & Whitney is going to disappear from the marketplace anytime soon. Given that reality, funding GE to develop a second engine for the F-35 makes about as much sense as funding P&W to develop a second engine for the B-3 (or whatever the next bomber will be called). The US cannot afford to develop two engines for everything.