Great photo of F-22 breaking the sound barrier

Originally posted by kilcoo316
Are you suggesting the F-22 has a combat range of 1,300 miles at 65K & M1.8?

I was being very conservative with the 650 mile combat range figure given the altitude and speed, total 1,300. So yes, all at Mach 1.8 and at 65K.

Originally posted by kilcoo316
Just wondering, because current sources would indicate the combat radius is 310+100nm (sub+super)[1], and that the ferry range of the F-22 is 1,700nm, which will be strictly subsonic with drop tanks.

Those figures are so misleading it's not even funny. I'm going by inference from pilot comments, not undervalued government figures. Do you really want to pretend that one of the most aerodynamically clean aircraft with efficient engines and 20,650 Lb of fuel on it can only fly for 410NM in combat? Come on now.

There were two ATF goals with respect to fuel and range. The ATF was envisioned as having a 700-750 mile combat range under supercruise. This would put virtually all of central and western Europe within quick range from the United Kingdom. Second, they wanted the ATF to carry as much fuel internally as the F-15C carries with full internal and three fuel tanks.

As I said before the F-22 has an internal fuel capacity of 20,650 lb (3,082 gallons), or roughly 10.3 tons. So far with the 4 external fuel tanks certified for it is has a total fuel capacity of 36,515 lb (5,450 gallons) or roughly 18.2 tons. Or about 28,582 lb with two fuel tanks.

The F-15C has an internal fuel capacity of 11,792 lb (1,760 gallons), or roughly 5.9 tons. This goes up to roughly 23,000 lb with 3 x 600 gallon fuel tanks. The F-15E with conformal tanks (see internal) has a fuel capacity of 21,842 lb (3,260 gallons), roughly 10.9 tons.

Anyone still think the F-22 has no legs?

[edit on 2-7-2009 by WestPoint23]

Originally posted by WestPoint23
I was being very conservative with the 650 mile combat range figure given the altitude and speed, total 1,300. So yes, all at Mach 1.8 and at 65K.

I'll shortly demonstrate how ludicrous that is.

Originally posted by WestPoint23
Those figures are so misleading it's not even funny.

Yes... because Lockheed are under-selling the aircraft.

Originally posted by WestPoint23
I'm going by inference from pilot comments, not undervalued government figures.

Lockheed figures... not government.

You can infer whatever you want from whoever you want. If it could do those range figures, Lockheed would be screaming it, and so would the USAF to get more under purchase.

Originally posted by WestPoint23
Do you really want to pretend that one of the most aerodynamically clean aircraft with efficient engines and 20,650 Lb of fuel on it can only fly for 410NM in combat?

Do you really want to start talking to me about L/D figures, fuel fractions and range?


The Breguet range equation (for turbofans) is as follows:

Range = 1/gravity * Speed * Lift/Drag * 1/Tsfc * ln(initial weight/final weight)

Tsfc is thrust specific fuel consumption (which is the amount of fuel consumed in an hour per unit of thrust produced). The F119 has *supposedly* a Tsfc of 0.78 lb/lbf.hr at full mil power (thats just what I've picked up along the way, it could be a bit lower).


I'm gonna circumvent the equation a bit. The L/D will be under 10 (10 would be absolutely ludicrously high for a fighter) - but we'll use it anyway to drop the 1/gravity term.

So:

Range = (1.8*660) * 1/0.78 * ln(64,500/(64,500-20,650))

Range = 590 miles



Or looking at it another way

Drag squares with speed (subsonically), and you know that the F119s in the F-22 produce approaching double the thrust of the F100s in mil power (~15,000 vs. ~25000). Which of course means approx double the fuel consumption.

The F-100 has an sfc of 0.76 lb/lbf.hr (@ full mil).

Which means the F-15 consumes 22,800 lbs of fuel in an hour and the F-22 39,000 lbs of fuel in an hour using the 0.78 mentioned earlier (at full mil thrust). Each aircraft does have 2 engines after all.

At that rate, the F-22 can go just over half an hour on full mil thrust. At Mach 1.8 that corresponds to a ground range of 630 miles or so.



So a supercruise range of 590 or 630 does roughly tie in with the radius of 300+100 [sub + supersonic], i.e ranges of 600 + 200 [sub +super].




Either way, your 1,300 miles range is absolute rubbish. Unless the F119 has a Tsfc of the order of 0.4 - which would be near half all fighter engines in the world - including the F135 which its rumoured has a Tsfc of 0.7 lb/lbf.hr.

Oh, and that would neglect the time taken to climb to 65K feet.

Originally posted by WestPoint23
There were two ATF goals with respect to fuel and range. The ATF was envisioned as having a 700-750 mile combat range under supercruise.

The ATF goal was 250+100. That is 250 sub + 100 super.


NOT 350 in + 350 out all supercruise. You speak as if cruising supersonically does not come at a cost in fuel consumption relative to cruising subsonically.

Originally posted by WestPoint23
As I said before the F-22 has an internal fuel capacity of 20,650 lb (3,082 gallons), or roughly 10.3 tons. So far with the 4 external fuel tanks certified for it is has a total fuel capacity of 36,515 lb (5,450 gallons) or roughly 18.2 tons. Or about 28,582 lb with two fuel tanks.

Anyone still think the F-22 has no legs?

Amateurs talk fuel loads, professionals talk fuel fractions.

F-22 = 20,650/66,470 = 0.31

F-15 = 14,400/44,500 = 0.32

Su-27 = 20,700/60,600 = 0.34

MiG-31 = 36,050/88,550 = 0.41

That is why the MiG-31 has the massive range it does.


When you bring fuel tanks into it, you are sacrificing your radar properties. You also then are sacrificing your clean aerodynamic profile.

I am comparing aircraft on internal fuel only.

Awesome!

It astounds me to be reminded time and time again how human technology has an impact on it's surroundings.

Especialy visualy!

Nice find!

Originally posted by kilcoo316
So a supercruise range of 590 or 630 does roughly tie in with the radius of 300+100 [sub + supersonic], i.e ranges of 600 + 200 [sub +super].

Those figures are closer to the ballpark. I admit my error. This article further supports the above.

"In stark contrast to the pilots of 4th generation machines, Raptor pilots exceed the sound barrier “multiple times on a daily basis”, Zuercher said. As such, the supersonic overland ranges around Holloman are an especially valuable training resource for the 49th FW aviators. Typically, depending upon the type of mission, a Raptor pilot will see speeds as fast as Mach 1.5 or Mach 1.6 “a few times a week”. More importantly, Zuercher emphasizes, is that “we can stay in those regimes for a very long time”. Zuercher added that he has flown the Raptor out to the aircraft’s maximum allowable speed under current regulations of Mach 2. Asked if he had ever come close to such speeds in the F-15, Zuercher answered, “The fastest I’ve ever flown the F-15 was around Mach 1.3, and in the F-15 you got to really be trying to go that fast”.

As a vivid illustration of what supercruise capability can afford, Zuercher shared an anecdote about a mission conducted by the 49th FW in October 2008. A flight of Raptors launched from Holloman to perform a strike mission inside the Utah Test and Training Range (UTTR). The aircraft cruised to their targets at over Mach 1.5 the entire way, dropped their bombs, before recovering at the nearby Hill AFB in Utah. After recovering at Hill, the aircraft immediately turned around and flew back to Holloman. Zuercher said the point of the exercise was simply “to see we could do it”.

Source

From Holloman Air Base to Hill Air Base is roughly 650 miles (considering supersonic corridors). It does not say, however, that this is the maximum supercruise range. Nevertheless, this is still a significant capability.

Originally posted by kilcoo316
Oh, and that would neglect the time taken to climb to 65K feet.

This was written by Lt. Col. Michael "Dozer" Shower. Now with the 94th FS in Elmendorf.

"At slower speeds the engines are not putting out maximum thrust, the more air flow there is through the motors the more thrust you're getting, so, for example, I did a takeoff where I was at about 570 knots at Edwards, I was prior to the end of the runway, not used to being that fast so I pulled up to 90 degrees nose high (single ship with my own tanker and first chance to try this with a Raptor so I decided to see what she'd do), and the mass flow at that point is close to producing max possible thrust, the a/c continued to accelerate in the climb to .99 mach passing about 20 thousand feet and then slowly began to decelerate - (unofficially according to the engineers I would have ended up around 65+ thousand feet on that day and broke every time to climb record we could think of for category & weight class -- and oh by the way, that wasn't a Streak Eagle or Flanker stripped down bare with weight removed, no external stores for combat configuration, etc., that was in a stock, off the line F-22, fuel of gas, combat configured with the internal weapons bay full - as an Eagle guy previous I was absolutely astonished, I hope someday we go after the official records because this jet will likely crush most of them.

One last interesting point is that I did that going straight up after takeoff (that day I ended up blasting past my assigned altitude at Edwards of 29 thousand after takeoff, ended up at 31.5 AFTER a 5g pull to level out which at that weight and altitude should bleed energy fast but when I rolled out I was still at 330 knots KCAS!!), but normally to get those altitudes they use a specific climb profile like the Streak Eagle did (I forget what it's called) climb at .9m to the mid 30 thousands, push over to accelerate to supersonic and then finish the climb profile to bust the records from there)."

It's comments like this and others that make me believe certain performance figures for the F-22 are purposely undervalued.