Forum: F-35 Lightning II

General rule of thumb is that the larger the bypass of an engine the heavier it gets because of the larger fan. The larger fan weight is a trade off for increased fuel efficiency and cooler exhaust temperatures. How ever looking at the turbine inlet turbine temperature the F-135 is one hot engine.

I've been reading up on the thrust to weight of the newer jet fighter engines.
Rafale M88-2= 18,000 lbs thrust/ 1,978 lbs = T/W 9.1
Eurofighter EJ-200= 20,250 lbs thrust/ 2,180 lbs = T/W 9.3
Raptor F-119= 35,000 lbs thrust/ 3,900 lbs = 9.0
F-35 F-135= 43,000 lbs thrust/ 5,400 lbs =7.96

The F-135 has a very low T/W of only 7.96 to 1. This is lower than some engines built in the 70's and 80's. Why?
This also seems low because it has a inlet temp of 3600 deg. F vs. only 2871 deg and 2700 deg for the M88 and the EJ-200.

What gives? Whatever help you can give would be great. Thank you.

Replace 43k with 50k. And that F119 figure should be closer to 40k.

Regarding the fact that the F-35 cannot supercruise.. Is that the matter of airframe disability/engine or both?

I did that the other day and got bashed on for three pages for not having my specs right. I've talked to a F-22 demo pilot and an F-35 test pilot(with crew) at an airshow out side Sac. CA. The F-22 pilot said it's about 39,000 lbs for the F-22 and the F-35 test pilot said the F-35 fully loaded in mil. power would out run an F-16 clean in mil. power. In my three page bashing I was told I was lied to.
50,000 lbs/5400 lbs =9.26
39,000 lbs/3900 lbs =10.0
Sound better to me given the temp of these engines. The lower T/W of the F-135 vs. the F-119 maybe because of the weight increase in getting the higher bypass ratio.

Thanks TSFG

From what I understand the airframe aerodynamics in most modern fighters wouldn't stop you from supercruising. As most 4th gen aircraft will do so clean or very lightly loaded. The engine seems to be the biggest issue. The F-119 in the Raptor makes twice the thrust of the F110 at high supersonic. The higher engine temp seems to help make thrust at altitude as well, do to the increased expantion of exhaust gas.
This is as I understand it. If I'm wrong somebody say something as this is how we all learn.
TSFG

Actually F-35s in military power were running away from F-16s in afterburner, which they had to use to keep up.

Any weight figure from P&W or the USAF ?
There seem to be a number of figures out there; Wiki cites 3750lbs for the F135.

Wiki is a crock. P&W says 3,900 lbs for the F-119 and 5,400 lbs for the F-135. P&W also says the F-135 is 1,500 lbs more than the F-119. Adds up to me. The 7.96 to 1 is what sounds low to me.
TSFG

Apart from definitions, anything above Mach 1 without afterburner shows off and is vital on the battlefiled. Lightly loaded F-16 also can go above Mach 1 - I don't know how far exactly but surely it can and it would be kinda weird if F-35 coluld not do the same..
But still Viper can go 2 times faster than the sound, while the Litening barely over 1 and a half of that speed. Regarding all factors like airframe shape, inlet(s) duct shapes (whether it constant or adjustable), overall drag, T/W ratio - is it only a matter of lack of thrust (F-16) or huge bypass ratio of F135 (F-35) that not allow these birds to hit somewhere Ma 1.3 or greater supercruise?
It would be interesting to see F-16 and F-35 both clean on the parallel runways taking off full throttle to see which one first break the sound. I'll still put my on Viper.

Btw, I've heard that in subsonic regimes the F-16 (clean) has comparable acceleration to the F-22.