Forum: General F-22A Raptor forum

This is on the AW&ST website:

Quote:

The U.S. Air Force is taking the F-22 Raptor to the Paris Air Show for the first time this summer, according to Larry Lawson, executive vice president and general manager of the F-22 program.

The trip to Paris has been long delayed. A furor that surrounded the detailed customs inspection and electronic surveillance of the F-117 the only time it went to France has apparently subsided.

The new U.S. administration has no grudge against France for not participating in the invasion of Iraq. Even recent concerns about the French air force’s electronic surveillance of the Indian Air Force’s Su-30 MKI during a 2008 Red Flag exercise at Nellis Air Force Base, Nev., has died down (Aerospace DAILY, Aug. 25). Moreover, the potential for additional U.S. sales and, possibly, foreign sales has removed any remaining barriers.

To pique consumer interest, Lockheed Martin has revealed better than expected performance for the stealth fighter.

The F-22s overperformance includes a radar cross section that is “better” than was contracted for, the company says. That classified requirement has been calculated at a -40 dBsm, about the size of a steel marble. By contrast, the F-35 is thought to be a -30 dBsm, the size of a golf ball. Supercruise is at Mach 1.78 rather than Mach 1.5. And acceleration – although company officials would not say from what speed or at what altitude – is 3.05 seconds quicker than the requirement of 54 seconds.

In nonafterburning military power the Raptor can operate at just more than 50,000 feet. However, it is known that the F-22 opened its aerial battles at about 65,000 feet during its first joint exercise in Alaska, apparently using afterburner.

There also is a mysterious admission that the range of the Raptor’s Northrop-Grumman/Raytheon active electronically-scanned array (AESA) radar is 5 percent greater than expected. That means a cushion of an additional 5-6 miles of detection range against enemy aircraft and missiles.

Supercruise at 1.78M! Wow...

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Meteor wrote:

This is on the AW&ST website:

Supercruise at 1.78M! Wow...

Fulghum is referencing a lot of the official site’s plus number he’s reported on but what’s interesting is that his aeroperformance figures he’s talking about appear to come from the MIL/1G/Ps=0 envelope that’s been circulated recently. It shows that the jet can’t supercruise much above 45,000ft (but it can reach ~M1.68 at that altitude) or above 50,000ft on dry thrust which is why I think he said “apparently using afterburner.” There exists the possibility that that envelope is sanitized as there have been other comments from pilots and program officials that hint at more. This one’s from a couple years ago and credit goes to sferrin for digging it up:

Quote:

[b]Pilots say new U.S. stealth fighter has no equal[/]]

BY: MELISSA NELSON , ASSOCIATED PRESS
12/22/2005

And then there is the Raptor's super cruise capability that lets it fly at supersonic speed without using fuel-guzzling afterburners as required by other fighters.

"That saves us a lot of gas and opens up a whole host of things when you start talking about dropping bombs," Krumm said. "You can imagine if you are 60,000 feet doing mach 1.9 (about 1,400 mph) and these bombs are flying out of your airplane, the swath of hell you can produce going through a country saying 'I'll take that target, and that target'."

Now granted he technically didn’t say supercruising at 60,000 ft etc. but the context of the quote is clearly about supercruise and what it kind of capability it allows. I seem to recall that Lt. Col. Showers’ commented about supercruise at 60,000ft on another board before it was taken down so it’ll be interesting to see if some “real” data start becoming public in the coming years (that’s a big IF)

BDF

The whole point of supercruise is to do it @ 50,000 ft or above.

Would I be off to far saying that the acceleration would have to be dead stop to max speed or max cruise? I recall a comment that from a dead stop takeoff to the end of the runway, mach 1 was nearly achieved. If that is the case then it would not be too much of a reach to say the acceleration mark that was beat by 3 sec. or 50 sec. to max cruise/speed.

How does the 50K w/o AB compare to legacy aircraft? And 65K w/ AB?

Imagine with the engine tweaking that goes on, what kind of performance we could see. The F-15/15 started out as 25K class engines now they are 30-35. Could we see an AC that cruises @ its top design speed? w/ dazzling acceleration. What kind of fuel consumption would they have, maybe bigger engines will not be feasible, considering fuel fraction.

With improvement to EW, RCS, engines etc., the F-22 will look the same on the outside but perform at a higher level, so to speak.

Definitely. I wouldn't bet against it reaching M. 2 supercruise before it's out of service.

Meteor wrote:

The F-22s overperformance includes a radar cross section that is “better” than was contracted for, the company says. That classified requirement has been calculated at a -40 dBsm, about the size of a steel marble. By contrast, the F-35 is thought to be a -30 dBsm, the size of a golf ball.

We can look at this two ways:

a; The F-22 RCS is pretty good, since it is a much larger aircraft than the F-35, but has a much smaller RCS.

or....

b; The F-35 RCS is somewhat disappointing, because despite the fact that it is a much smaller aircraft than the F-22, it has a substantially larger RCS.

Part of the problem is the RCS reducing coatings on the aircraft and the thermal loads they can stand up to. I believe that's more of a limiting factor to the aircraft than engine life cycle upgrades. Going Mach 3 but peeling the paint off isn't good. I think the real development is in watching the paint dry *sigh*.

Edit cause I aer ngineeeeer and engrish nto so gud.

strykerxo wrote:

Would I be off to far saying that the acceleration would have to be dead stop to max speed or max cruise? I recall a comment that from a dead stop takeoff to the end of the runway, mach 1 was nearly achieved. If that is the case then it would not be too much of a reach to say the acceleration mark that was beat by 3 sec. or 50 sec. to max cruise/speed.

How does the 50K w/o AB compare to legacy aircraft? And 65K w/ AB?

Imagine with the engine tweaking that goes on, what kind of performance we could see. The F-15/15 started out as 25K class engines now they are 30-35. Could we see an AC that cruises @ its top design speed? w/ dazzling acceleration. What kind of fuel consumption would they have, maybe bigger engines will not be feasible, considering fuel fraction.

With improvement to EW, RCS, engines etc., the F-22 will look the same on the outside but perform at a higher level, so to speak.

Howdy!

Not sure if it provides any answers, but this dated AFA presentation shows some slides (p. 23 - 32) comparing a few simplified F-15C and F-22 mission profiles including som dash intercept, altitude, mach and combat radius figures. I'm not sure if the Eagle is compared with or without CFTs, and being lazy I'll let someone else to figure out the math. Wink

B. Bolsøy
Oslo

LordOfBunnies wrote:

Part of the problem is the RCS reducing coatings on the aircraft and the thermal loads they can stand up to.

An expert on RCS matters once stated that the four most important factors in stealth design were, in order; shape, shape, shape, and materials. While coatings are a factor in stealth, the vast majority of "stealthiness" comes from the mold line or planform of the aircraft, not materials.

The size and shape of the F-35 were dictated by the USMC need for V/STOL. If it were not for the V/STOL requirement, the F-35 would probably be even stealthier than the F-22.

I thought the F-35 was intentionally given a larger RCS than the F-22 because it was being planned for export?

If I were a USAF F-35A pilot going into a fight to the death flying an "F-35 was intentionally given a larger RCS than the F-22 because it was being planned for export", I'd be rather pissed.

energo wrote:

Howdy!

Not sure if it provides any answers, but this dated AFA presentation shows some slides (p. 23 - 32) comparing a few simplified F-15C and F-22 mission profiles including som dash intercept, altitude, mach and combat radius figures. I'm not sure if the Eagle is compared with or without CFTs, and being lazy I'll let someone else to figure out the math. Wink

B. Bolsøy
Oslo

Very interesting. Kind of difficult to deduce anything on the F-22's supersonic range from this presentation other than the supersonic fuel burn appears to be about half of the Eagle's. The jet’s supercruise range has always been controversial and we’ve seen specific range values of 0.04 lb/nm at mach 1.5 and 45K ft [Stevenson et. al & general agreement w/ AFA values] which translates to a supersonic range of roughly 500nm for 12,400lbs of gas (2/3rds rule of thumb for ingress/egress).

The data from those sources stops at 45,000ft yet we’ve heard anecdotal evidence such as the one above that the jet can supercruise at 60,000ft which would improve fuel burn considerably. Right now the most reliable anecdote I’ve seen is the June 2006 report in AvWeek detailing F-22’s importance in cruise missile defense highlighting its ability to cruise supersonically “at about mach 1.5” for 41 minutes or a range of 695 nm; this translates to a specific range of roughly 0.056 lb/nm which interestingly is almost exactly what I was able to extrapolate from the data in the Stevenson data for M 1.5 at 60,000ft.

What I think is the most interesting aspect of the presentation is the effect supercruise has on survivability. Against SAMs the rate of survivability is twice that at M 1.7 than M 0.9 for the same signature (4th order of magnitude; i.e. -40 dBsm); now compared to M 1.7 4th order to M 0.9 3rd order magnitude the rate of survivability is now roughly 3.5 times more. Where it gets really interesting is against fighter threats. In the first scenario the survivability M 1.7 to M 0.9 and same signature is 4.5 times more and goes to 5 times for 4th to 3rd, M 1.7 to M 0.9.

BDF

Tinito_16 wrote:

The whole point of supercruise is to do it @ 50,000 ft or above.

Why?

Kryptid wrote:

I thought the F-35 was intentionally given a larger RCS than the F-22 because it was being planned for export?

Actually, the RCS was not pushed to keep costs down. It is to the F-22 what the Viper was intended to be to the Eagle, i.e. cheaper and in significantly more numbers.

Roscoe wrote:

Kryptid wrote:

I thought the F-35 was intentionally given a larger RCS than the F-22 because it was being planned for export?

Actually, the RCS was not pushed to keep costs down. It is to the F-22 what the Viper was intended to be to the Eagle, i.e. cheaper and in significantly more numbers.

and

Meteor wrote:

If I were a USAF F-35A pilot going into a fight to the death flying an "F-35 was intentionally given a larger RCS than the F-22 because it was being planned for export", I'd be rather pissed.

All things being equal, there's no arguing that a lower RCS is better. However, resources required rises exponentially (both in acquisition and sustainment) as RCS is lowered, translating into more spending (less likely) or fewer aircraft. I wouldn't have a problem giving up a little RCS if that meant I could have a 4-ship vs a 2-ship with me in combat.

Forum: General F-22A Raptor forum

F-22 performance statistics released