[Josh]

OT, but a question that doesn't deserve its own thread:

I've seen various figures given for the F-22's cruise/patrol altitude. They start at around 50,000 feet and go up as high as 65,000.

65,000 seems really high even for an a/c of F-22's size and power and usually takes some serious wing area a la U-2/RQ-4.
But even given the lower range, one assumes the F-22 is perfectly capable of zoom climbing to that altitude if needed.

So my question: wouldn't F-22 pilots potentially need pressure suits as are used by U-2's?




Also while we're at it, anyone hear any feedback on the F-22 in Red Flag? I read an account of 'Northern Edge' recently that said they not only were mopping up all other a/c but they were helping other a/c mop up red targets as well--on top of the 144 to 0 exchange rate there was something like ~230 to 2 exchange rate in air to air combat over all between red and blue. A little hard to take too much aware from that not know the exact circumstances, but still...

[JamesG123]

The F22 has a "lifting body" fuselage. It could fly without any wings at all. They are there for low speed flight (takeoffs and landings) and someplace for control surfaces.

The Raptor has been in development for nearly a decade now. You would think that they would have had a procurement plan and contract hammered out a long time ago...

[Gunguy]

The F-22 I saw did not seem to have a lifting body fuselage. Especially once the bomb bays are open (missile bays). Those big wings are for lift and dogfighting. Also, the F-22 has "post stall manuever capability" but it seems to be classified as I have not seen anything in detail on this capability. This is considered a large edge for a dogfight.... I'm no expert on dog fights, so I take them at their word. It would be nice to have a good quality F-22 book come out like they did for the F-15 and 16. They had info in the books that was "classified" by the military (ten years later) even though it was in print and sold all over the western countries....... great reading.

[Brad F]

Lt. Col. Michael “Dozer” Shower has stated that the USAF lifted the 50,000’ rule for pressure suits for the Raptor and they have a self imposed 60,000’ limit to keep from flirting with the Armstrong line, although he’s been higher. The ability of the F-22 to reach said altitudes isn’t one just of wing area (wing loading) but also of thrust; i.e. min mach to sustain level flight at those altitudes. It’s a good bet that the F-22 is supersonic up there.

Brad

[JamesG123]

What is still classified is that the F22 is actualy an aerospace fighter built with alien technology. Oooooooo :D

[Tranquil]

Gunguy, on Wed 9 May 2007 1739, said:

Also, the F-22 has "post stall manuever capability" but it seems to be classified as I have not seen anything in detail on this capability. This is considered a large edge for a dogfight....

Also known as Thrust Vector Control. Which is certainly nothing new in the world of combat aviation. Employment of TVC in the raptor may indeed be related to high altitude performance. Not a lot of air all the way up there for traditional control surfaces.

[TonyE]

JamesG123, on Thu 10 May 2007 0232, said:

What is still classified is that the F22 is actualy an aerospace fighter built with alien technology. Oooooooo :D

According to rumors it can also teleport to anywhere in the world, take out enemy communication and airdefencenetworks by the sheer power of its onboard radar and shot down enemy fighters while flying completly unarmed. It`s the best i tell you, THE BEST!

[seahawk]

Acutally it is THE BEST.

It is a much a breakthrough as the F-15 was in 1975 compared to then flying fighters and as much as the F-4 was to the previous generation.

Cruising at Mach 1+ at 60.000 feet with the RCS it is sid to have, this thing is harder to interecept then a SR-71.

[Chris Werb]

Tony Engelsen, on Thu 10 May 2007 1048, said:

According to rumors it can also teleport to anywhere in the world, take out enemy communication and airdefencenetworks by the sheer power of its onboard radar and shot down enemy fighters while flying completly unarmed. It`s the best i tell you, THE BEST!

It's a good job it's not relying on the sheer power of the intellect of some of its proponents.

[Josh]

seahawk*, on Thu 10 May 2007 1003, said:

Acutally it is THE BEST.

It is a much a breakthrough as the F-15 was in 1975 compared to then flying fighters and as much as the F-4 was to the previous generation.

Cruising at Mach 1+ at 60.000 feet with the RCS it is sid to have, this thing is harder to interecept then a SR-71.

Actually I'd say its a bigger step forward than the F-15 was over the F-4. The radar, weapons, and general performance increases are similar between the two upgrades, but the service ceiling, cruise speed, and RCS weren't improved much in the F-15 compared to the F-22 over the F-15. Put another way, if a flight of four F-4's went up against an F-15 the winner would be in some doubt. Apparently in exercises, there isn't much doubt who wins when an F-22 comes up against similar numbers of F-15. And considering the cost of development in time and money it should be so, quite frankly.

Brad F, on Wed 9 May 2007 2046, said:

Lt. Col. Michael “Dozer” Shower has stated that the USAF lifted the 50,000’ rule for pressure suits for the Raptor and they have a self imposed 60,000’ limit to keep from flirting with the Armstrong line, although he’s been higher. The ability of the F-22 to reach said altitudes isn’t one just of wing area (wing loading) but also of thrust; i.e. min mach to sustain level flight at those altitudes. It’s a good bet that the F-22 is supersonic up there.

Brad

Thanks, I was figuring that the either the altitudes quoted had to be wrong or someone had to change the rules (not personally knowning what the rules are). What is the 'Armstrong line'? And these rules seem a little arbitrary; what is the physical limit to how high a human can go pressure wise assuming a steady supply of oxygen?

Its pretty clear the F-22 can be supersonic at high altitude if it wants to, though quotes I read about the 'Northern Edge' exercises indicate the F-22's would spend a lot of time loitering sub sonic waiting for targets and conservng fuel, so apparently the wing area is sufficient such that the plane not go to full military power to maintain altitude.

Specifically a pilot stated:

"We could sit up at high altitude and save our gas and watch. We don't hang out at Mach 1.5. With our acceleration, when we saw the threats building, because we could see them so far out, we'd dump the nose over, light the burners and we were right up to fighting speed."

http://www.aviationw.../aw010807p1.xml

[Mote]

Quote

What is the 'Armstrong line'?

Quote

The Armstrong Limit is the altitude that produces an atmospheric pressure so low (.0618 atmospheres), that water boils at the normal temperature of the human body: 37°C (98.6°F) [1].

The altitude, also sometimes referred to as Armstrong's Line, is variously reported as being between 18.9 km - 19.4 km (62,000 - 63,500 feet) (about 11.8 miles) [2] [3]. At or above this point, exposed human fluids will boil without a pressure suit, and no amount of breathable oxygen, delivered by any means, will sustain life for more than a few minutes. A human would, eventually, boil in their own body fluids (a process known as ebullism), though death from asphyxiation would occur first, as the barrier of the skin and control of blood pressure would prevent blood from boiling immediately [4].

A NASA technical report, Rapid (Explosive) Decompression Emergencies in Pressure-Suited Subjects, discussing the brief accidental exposure of a human to near vacuum notes the likely result of exposure to pressure below that associated with the Armstrong Limit: "The subject later reported that ... his last conscious memory was of the water on his tongue beginning to boil."

http://en.wikipedia....Armstrong_Limit

[Josh]

Silly question: I assume fighter a/c are pressurized or else you'd freeze at 30K feet. So why the oxygen masks? Just to force higher pressure O2 in hard manuvers?

As far as the Armstrong Limit, seems to me a human could tolerate exposure with an O2 supply pretty easily since bodily fluids are not that exposed. So in a depressurizing event above 60K' you'd have time to bring the a/c lower so long as you had oxygen.

[BansheeOne]

Except that oxygen will not transfer to your blood with insufficient pressure.

[Brad F]

jua, on Thu 10 May 2007 1448, said:

Silly question: I assume fighter a/c are pressurized or else you'd freeze at 30K feet. So why the oxygen masks? Just to force higher pressure O2 in hard manuvers?

As far as the Armstrong Limit, seems to me a human could tolerate exposure with an O2 supply pretty easily since bodily fluids are not that exposed. So in a depressurizing event above 60K' you'd have time to bring the a/c lower so long as you had oxygen.

Most fighters have limited pressurization for crew comfort. Most can put up about 3 psi cabin differential although the F-22 might be more. This isn’t enough to maintain high enough O2 partial pressure for adequate cognitive abilities and in that regard breathing 100% O2 is a must for maximum alertness and eye function.

My understanding is that the F-22’s Combat Edge/ATAGS has been chamber tested up to 66,000’ and is designed to give the pilot enough time get down before he becomes incapacitated.
Brad

[Josh]

BansheeOne, on Thu 10 May 2007 1536, said:

Except that oxygen will not transfer to your blood with insufficient pressure.

Isn't the O2 in a pilots mask pretty much at atmospheric pressure?

Also, on that note, I remember that there was a system being looked at that force fed high pressure oxygen to pilots, not for high altitude but for hard manuvers to prevent GLOC. I believe it was found to be rather successful. Does any organization use such a system? Does anyone use anything more complex than old school G-suits?

[BansheeOne]

The oxygen itself may be at atmospheric pressure, but AIUI it will no longer dissolve/bind to the hemoglobin due to lack of ambient pressure long before your blood will start to "boil". Nelson DeMille described that scenario in "Mayday" where a supersonic airliner gets accidentially hit by a test missile at 60,000 ft and returns with a load of brain-damaged passengers and crew though everybody put on their oxygen masks (except for the usual PPL holder/stewardess/little kid who happened to be in semi-sealed areas while the plane descended on autopilot and proceed to save the day).

As for anti-G systems, the trend actually seems to be towards the less complicated, like the Libelle suit.

[Josh]

Just thought I'd tag another OT post on the thread since this isn't worth its own. Thought this was a funny quote:

""I can't see the [expletive deleted] thing," said RAAF Squadron Leader Stephen Chappell, exchange F-15 pilot in the 65th Aggressor Squadron. "It won't let me put a weapons system on it, even when I can see it visually through the canopy. [Flying against the F-22] annoys the hell out of me."

[JamesG123]

There is still the gun. <_<