Is the Raptor capable of this...

Originally posted by RichardPrice
Carbon Carbon composite is also incredibly brittle and not good for constant use aircraft.

Case in point the space shuttle. Foam cracked the carbon carbon leading edge.

The bottom line is this. Could the airframe itself handle Mach 3 speeds? Maybe, however, none of the systems that the SR-71 (fuel used a heat sink) or the XB-70 (stainless steel honeycomb) used to deal with heat are present on this plane. The internal components would not be able to deal with the heat and would fail pretty quickly. One A-12 flight, the air speed inlet malfunctioned and the plane went as high as 3.45 or 3.5 and when it landed all the wiring had been crisped any longer and the internal systems would have failed.

Also as some have pointed out its IR signature would be big and defeat the purpose of being stealthy. The Mig 29 if I recall has an IRST built in right?

Also, would it be able to sustain those speed for a meaningfull duration with its internal fuel load?

As most of the others have pointed out, the F-22 was not design to fly that fast! Remember, the faster you fly, the less meneuvable the aircraft becomes. The main goal of the F-22 was to be highly menuvable in A2A combat. For the F-22 flying at Mach 3 wouldn't help it achieve it's mission!

Also, Mach 3 flight is very expensive! Look at the cost that were spent on planes like the A-12/SR-71 Blackbird, XB-70, and Mig-25 Foxbat to get speed in this range! The idea of trying to go Mach 3 in the F-22 sound rediculas! Why would anyone want to fly it that fast? there are no enemy fighters that fast.

Tim

ummm not to under mind yah ghost but that could be a reason to fly that fast. ie out run enemy planes once it has fired its missiles, but i do know that the raptor can't do that even though it would be kind kool to have a plane with the speed of the sr-71's and the radar and weapons of the 22's.

Originally posted by Seekerof
This is the second time you have asked me this.
Can I allow this to answer your question?

Page Two: My Second post down






seekerof

[edit on 24-7-2005 by Seekerof]

Ahh, okay, sorry man, the first time I asked, I missed your response I guess (sorry about that). That's awesome though. Pararescueman are one of the hardest Special Operations components to join (not that you wouldn't know).

Well, I just realized where the Mach 1.72 figure came from.....it came from the latest book by Jay Miller called Lockheed Martin F/A-22 Raptor

Mr. Miller asserts that the F-22 can supercruis at Mach 1.72, which he then notes as actually being Mach 1.82+. Mr. Miller then goes on to say that the F-22 has been officially clocked at having a top speed of Mach 2.25+, which he then asserts is faster than has been previously officially acknowledged.

He goes on to mention that the F-22 has a sustained G which is Mach 1.8 at 6G's, and having a roll rate of 100 degrees per second, while carrying an internal 22,000lb. full load of JP-8. That the F-22 has a service ceiling of 65,000 feet, but would operate mainly around the mid-50,000 feet range to maximize its inherent advantages.

More evil things mentioned about the Raptor by Mr. Miller:

* Third, this is a dogfighter. The aircraft can maneuver into realms of the flight regime that would put other fighters into deep stalls and spins. To help the aircraft through these regimes are a pair of Pratt & Whitney F119 engines with vectoring exhaust nozzles.

* Finally, the F-22 is the most automated (computer-controlled) machine in the sky. The pilot still moves the stick, throttles and rudders, but computers manage the aerodynamics, engines, sensors, communications, countermeasures, etc. In short, if they could have spared the radar cross-section, there'd be a dome behind the cockpit representing the head of R2-D2.

seekerof

[edit on 27-7-2005 by Seekerof]

Originally posted by Figher Master FIN
I've read a lot about the F/A 22 or the "Raptor"... I was jsut wondering what the Raptors real top-speed is... On several sites I've seen taht the top-speed only would be from 1.7-2 mach... But ATS claims that the plane is capable of Mach 3 preformance... What is the truth...?

Max Speed: Mach 1.8 - Mach 2.0 (Apparently capable of a Mach 3 performance)

abovetopsecret.com...

I once saw an interview with an F-22 test pilot and he said that although we couldn't reveal the plane's specs the F-22 was a well above Mach2 class plane

www.edwards.af.mil...

Straight from edwards airforce base.

Commenting on the flight, Lt. Col. C. D. Moore, F-22 Combined Test Force commander here, said: "Sustaining the target Mach was not difficult for the Raptor. The difficulty was keeping the Raptor from going faster than the target speed. Yesterday, the airplane demonstrated that it can achieve awesome speed, flying above Mach 1.5 at a low power setting, for a sustained period of time. No other fighter in the world can do that.

Lockheed Martin says :

Performance estimates give the F-22 a speed of Mach 1.5 in non-afterburning supercruise mode, and a speed of Mach 2.0 or above with afterburner. Service ceiling is thought to be over 15 kilometers (50,000 feet) and the maximum range is believed to be over 3,000 kilometers (1,860 miles). Flight tests demonstrate that the F-22 combines good handling characteristics with very high maneuverability. The F-22 is 18.9 meters (62 feet) long, with a wingspan of 13.6 meters (44.5 feet) and a height of 5.2 meters (17 feet). While the USAF is quiet about many of the Raptor's specifications, it is estimated to have an empty weight of about 15 tonnes (16.5 tons) and a fully loaded weight of about 27 tonnes (30 tons).

The term "supercruise" may confuse people into thinking that is the term for its top speed, which it is not. Supercruise is the term for its LOW powered supersonic flight. The F-22's ability to supercruise at speeds ABOVE Mach 1.5 at a LOW power setting is accomplished by its high output fuel efficient jet engines, and its vectored thrust. The vectored thrust can shrink its size, accomplishing what I would call the garden hose effect. Have you ever pushed your thumb over the end of a garden hose in order to get more thrust? Im sure you have.

If the F-22 can fly Mach 1.5 at a low setting, imagine what it can do at a high setting! Then add afterburn to that high speed supercruise. Mach 3.0 should not be ruled out. I know its possible with this craft.

They claim they built this jet for 3 reasons. Stealth, Manuverability, AND Speed. Not just Stealth and Manuverability.

Someone stated the speed would increase its IR signature and would compromise stealth. That is false, they designed this jet so that its engines exhaust is deap inside the fuselage to hide most heat. Its high aerodynamics and special design reduces its radar cross section (RCS), and reduces friction with air to give it a much smaller heat signature.

IntelGirl says that stealth compromised its speed because the jet was built WITHOUT variable geometry inlets. Variable geometry inlets are used to change the size of the jet engines air intake, to optimize for speed. You would think that because the F-22 was built with fix inlets it would compromise speed, but Lockheed has removed that problem. They designed the inlets for optimized air intake for the two Pratt & Whitney F119-PW-100 engines (155.69 kN / 35,000 lb st with afterburning each) so that while in supersonic flight the engines will not starve for air. They are tuned for the purpous of speed, and still keep its stealth. Pilots of the F-22 are trained to only reach supersonic flights at a predetermined altitude for max preformance.



[edit on 29-7-2005 by Deny0rder]

Originally posted by Deny0rder
Someone stated the speed would increase its IR signature and would compromise stealth. That is false, they designed this jet so that its engines exhaust is deap inside the fuselage to hide most heat.

Aerodynamics or not, you cannot get around airframe heating period. Also Mach 3 would require afterburners and those are hard to hide as well. Thats why you have the platapus exhause n the F-117 and the the B-2 uses the airframe to partialy sheild the plume from the ground. The YF-23 also had this feature.

Remember that parts of the SR-71 airframe got as hot as 550 or so. How exacltly do you propose to keep the internal componets cool enuf?

[edit on 7/29/05 by FredT]

Originally posted by Deny0rder
Someone stated the speed would increase its IR signature and would compromise stealth. That is false, they designed this jet so that its engines exhaust is deap inside the fuselage to hide most heat. Its high aerodynamics and special design reduces its radar cross section (RCS), and reduces friction with air to give it a much smaller heat signature.

The presense of afterburners would massively compromise any stealth design, by increasing the IR output several hundred times. This is the whole point of supercruise, and unless you are saying the F-22 can supercruise to its maximum speed, then there is a point where the IR signature heads for the skies (no pun intended).

Variable geometry inlets are used to change the size of the jet engines air intake, to optimize for speed.

In the context it was used, variable geometry inlets are not used to increase the size of the intake, but to ensure that the shockwave created by the air entering the intake will always hit the compressor stage fan and not the center or the sides of the intake, which would induce huge amounts of drag and possibly create compressor stalls.

The biggest point of variable inlets is to slow the air to subsonic speeds. Air hitting the compressor blades at supersonic speed would shatter them. By having the inlet retract into the engine somewhat, it decreases the amount of air that can get to the compressor, and causes it to slow to subsonic speeds.

[edit on 29-7-2005 by Zaphod58]

Someone stated the speed would increase its IR signature and would compromise stealth. That is false, they designed this jet so that its engines exhaust is deap inside the fuselage to hide most heat. Its high aerodynamics and special design reduces its radar cross section (RCS), and reduces friction with air to give it a much smaller heat signature.

I made that statement, though I can't remember if I was first or not. It is absolutely NOT false either.

As the other guys have pointed out, heating the airframe is unavoidable. Raptor has some clever stuff to reduce the effect but it is still there, and, although heat levels are negligible at supercruise speeds as was intended, it is increased as the speed goes up and as such can be detected by systems such as PIRATE etc. The Raptor does extremely well to maintain a stealthy profile at supersonic speed ( in itself unthinkable a few years ago) but the fact remains that once the pilot has made the decision to go to afterburner then 'stealth' no longer exists and other considerations would have forced the choice.

I also wonder what 'high aerodynamics' means and how they differ from 'low aerodynamics'?

waynos, typically, I would agree and you would be correct on the IR issue on detection, but in the case of the Raptor, detection by IR has been so radically reduced, that other than afterburners, IR detection on the Raptor is minimal to nil.





seekerof

Oh yes, I agree that you are right there, as long as the aircraft is supercruising. What I am talking about is when the Raptor goes beyond that speed, but by then of course the heat from the exhausts would be much easier to detect than airframe heat anyway and once that happens stealth is out of the window. I tried to say that but perhaps not very clearly (it was the bit about maintaining a stealthy profile at supersonic speeds)

Well... I never said the jet would be completly stealth durning its high speed flight above mach 2.0. I hinted that its IR signature would be drasticaly lower than one might think.. Theoreticaly a jet producing that much power and traveling at that speed would raise its IR becase of many different factors. But let me tell you that there was a lot of research, and testing that went into the design of this aircraft. Some of which is still classified. Methods to reduce and hide or store heat would include the use of exotic metals, special machining techniques to disperse and rid away heat like a heatsink on a computer cpu, and thermal insulation that can stop or slow conduction of heat, from solid to solid, and gas to solid, and even liquid to solid.

www.school-for-champions.com...

I also wonder what 'high aerodynamics' means and how they differ from 'low aerodynamics'?

I made a mistake.. i ment to say HIGH SPEED Aerodynamics often called compressible aerodynamics.

www.vzlu.cz...
www.grc.nasa.gov...

Apposed to LOW SPEED Aerodynamics.

www.vzlu.cz...

Originally posted by RichardPrice
The presense of afterburners would massively compromise any stealth design, by increasing the IR output several hundred times. This is the whole point of supercruise

No, the WHOLE point of supercruise is not just for stealth, it is also for range. To save fuel, and have maximum speed.

What I tried to say, was that at supersonic speeds, the jets stealth IS NOT fully compromised because of its design. You said it was COMPLETLY COMPROMISED, which is false. I understand that using the afterburners would raise the heat in the rear, but with a jet like the raptor, you wouldnt need 100% stealth when you can out run any missle, jet, or threat. Afterburners are almost like rockets, its a direct fuel feed to the engines exhaust. Afterburners would increase the heat A LOT but heat-resistant components give the vectoring nozzles of the jets exhaust the durability needed to vector thrust, even in afterburner conditions and has features that contribute to the aircraft stealth requirements (which are classified).

Here is a lot about the engines:
www.globalsecurity.org...



back to the subject... I firmly believe this jet can reach mach 3.0 max.


[edit on 29-7-2005 by Deny0rder]

Originally posted by Deny0rder
If the F-22 can fly Mach 1.5 at a low setting, imagine what it can do at a high setting! Then add afterburn to that high speed supercruise. Mach 3.0 should not be ruled out. I know its possible with this craft.

Mere wishful thinking from your part. Your patriotism won't make it fly faster.

Originally posted by Deny0rder
That is false, they designed this jet so that its engines exhaust is deap inside the fuselage to hide most heat.

This shows you don't know what you're talking about. The exhaust comes still out of the back of the plane and since the F119 is a low bypass ratio turbofan anyway and the amount of mixing of air inside a length much smaller than the length of the plane is minimal, the location of the engine does absolutely nothing regarding the infrared signature. The reason for hiding the engines inside the fuselage is to prevent radar waves from bouncing off directly from the fast spinning turbine blades, which would be a dead giveaway.

Ok thank you... Now I know much more about the Raptor...

Thanks to everybody who have posted to this thread... I have nothing more to say...

Non Mil power settings can indeed achieve Mach 1.5, the acknowledged top end in the supercruise regime is approx M 1.7-1.8. Top end is in excess of Mach 2.4. But its academic, the fuel fraction of the jet is about the same as an F-15. As disclosed by the USAF themselves, they expect a mixed subsonic/supercruise mission radius on internal fuel to only be about 455nm and pure subsonic mission radius of 595nm. Quite good really, but not what was expected of it given the original ATF specifications of 750nm.

ok... Now we know so much about speed taht I'am about to faint...

Now, I just noticed that i wasn't quite finnished... Dear Seekerof

Originally posted by Seekerof

Obviously, to novices and arm-chair generals, speed is the main factor, eh?

seekerof

[edit on 24-7-2005 by Seekerof]

About those generals, yes, they dont care about anthing else. Because they have other staff worrying about it... If a general would worry about those things it wouldn't work, they have far more important things to do... And those generals, arent maybe as brave as the ones in the battlefield... But does everybody have to be brave...

BTW, I herad that you are in the army, did you even think taht those arm-chair generals are the ones who decide if you go to battle or stay at home...

[edit on 30-7-2005 by Figher Master FIN]

Originally posted by Figher Master FIN


About those generals, yes, they dont care about anthing else. Because they have other staff worrying about it... If a general would worry about those things it wouldn't work, they have far more important things to do... And those generals, arent maybe as brave as the ones in the battlefield... But does everybody have to be brave...

BTW, I herad that you are in the army, did you even think taht those arm-chair generals are the ones who decide if you go to battle or stay at home...

[edit on 30-7-2005 by Figher Master FIN]

FIN, Not meaning to belittle you in any way, but the term "Armchair General" refers to a civilian who tries to second guess military planners, it is not a General with a desk job.

An "Armchair General" usually starts off his sentence with, "What they ought to do is..." or "Why don't they ..." - just as an observation, ATS has no shortage of these civilian "generals".

Therefore it is not "armchair generals" that make any military decisions, also, Seekerof was USAF not US Army.





[edit on 30-7-2005 by intelgurl]