F-22 Raptor speed

Anything goes, as long as it is about the Lockheed Martin F-22 Raptor
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skyhigh

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Unread post03 Mar 2009, 12:47

Kryptid wrote:Ah, so on the MiG-25, the engines would fail before the airframe would, but the opposite is likely true of the F-22? Those F119s are hot stuff...


That's right. The Tumansky R-15B-300 turbojets drank fuel like a thirsty trekker in the Sahara, and once, an Egyptian MiG-25 pilot blew out the turbojets at Mach 3.2 (ca. 3400 km/h) like popping a pair of balloons.
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xhack2

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Unread post26 Jun 2017, 16:01

Hello guys!

Long time lurker of this site since my days playing Falcon 4.0, just registered today.


I do have a question, hopefully you find this related, but what is the max speed that the Raptor's bay doors can remain open, or opened for an AIM9 or Amraam Launch?

just curious
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wrightwing

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Unread post26 Jun 2017, 17:10

xhack2 wrote:Hello guys!

Long time lurker of this site since my days playing Falcon 4.0, just registered today.


I do have a question, hopefully you find this related, but what is the max speed that the Raptor's bay doors can remain open, or opened for an AIM9 or Amraam Launch?

just curious

Let's put it this way. There isn't a scenario where an F-22 would have to slow down, to engage a target.
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Unread post29 Jun 2017, 19:24

Going to be a long time before anyone outside of a select few know her top speed, but it's fun to guess. Personally, I feel it's true top speed is around Mach 2.8, super-cruise mach 1.8 (now, perhaps mach 2 if and when the engines are up-rated).

I am still kicking myself for not bookmarking it, but I swear there's a quote from a pilot stating something to the effect that, "we haven't seen closing speeds like this since the Foxbat/Foxhound". I'm guessing that's probably not far from the truth, given both the Foxbat/Foxhound carry external stores - and the Raptor doesn't...
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Unread post04 Jul 2017, 11:07

Mach 2.8... And how could it deal with the airflow into the engines?

I'm not a specialist, so i ask other people who got a better understanding of the subject, they consider a top speed above Mach 2.0 is very unlikely due to the type of air intake on the F 22.

If you got some informations about that, would be curious to know more.
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disconnectedradical

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Unread post04 Jul 2017, 14:05

mixelflick wrote:Going to be a long time before anyone outside of a select few know her top speed, but it's fun to guess. Personally, I feel it's true top speed is around Mach 2.8, super-cruise mach 1.8 (now, perhaps mach 2 if and when the engines are up-rated).

I am still kicking myself for not bookmarking it, but I swear there's a quote from a pilot stating something to the effect that, "we haven't seen closing speeds like this since the Foxbat/Foxhound". I'm guessing that's probably not far from the truth, given both the Foxbat/Foxhound carry external stores - and the Raptor doesn't...


Bullcrap.

I don't get why people have to launch these hyperboles. The F-22 would look very different if it can make Mach 2.8, from inlets, to propulsion system, to the materials, to the canopy. The F-22 inlet looks to be external compression and seems to be 2 shock (1 oblique and the normal), but efficiency will really suffer at speeds well above Mach 2.2 compared to 4 shock systems like on the F-15.

The F-22 isn't going to dash at Mach 2.8, nor does it need to in order to be the most effective fighter. For the record, an new and spit clean F-15C with the -220 engines will do Mach 2.45 max on standard day conditions. With launchers attached (and no weapons) it drops down to around Mach 2.35, a number I don't think the F-22 will differ from much, assuming the materials can take it.
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mixelflick

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Unread post04 Jul 2017, 17:23

Perhaps, but you're guessing much like I am.

Only a very few know her top speed, and you can't rule out Mach 2.8 anymore than I can rule out 2.42 (or whatever). Just because every other aircraft up to the F-22 with fixed inlets can't achieve much above mach 2 doesn't mean that holds true for the Raptor. As anyone can see, the aircraft is a kinematic monster, and the Air Force long ago released plenty of performance figures exceeding its design objective(s).

It's been said that the Raptor was designed to beat (and handily) any near peer adversary for the next 30 years. So if the PAK FA has variable inlets and gets the right engines, it might be capable of dash speeds in excess of Mach 2.5. We already know the Mig-31 is capable of Mach 2.8. I don't think the air force is going to re-design the thing to be able to chase down a Mach 2.5+ jet. I believe the capability is already there...
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sferrin

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Unread post04 Jul 2017, 17:43

niafron wrote: they consider a top speed above Mach 2.0 is very unlikely due to the type of air intake on the F 22.


Most people can't get past, "hurrrr, fixed-inlet, so it can't go Mach 2". This is demonstrably absurd since there are numerous air-breathing vehicles that go FAR beyond Mach 2 with "fixed inlets". Here's one:

XF8U-3-Crusader-III-Featured-Image.jpg
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SpudmanWP

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Unread post04 Jul 2017, 19:46

And another... (with or without DSI)

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disconnectedradical

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Unread post04 Jul 2017, 23:03

mixelflick wrote:Perhaps, but you're guessing much like I am.

Only a very few know her top speed, and you can't rule out Mach 2.8 anymore than I can rule out 2.42 (or whatever). Just because every other aircraft up to the F-22 with fixed inlets can't achieve much above mach 2 doesn't mean that holds true for the Raptor. As anyone can see, the aircraft is a kinematic monster, and the Air Force long ago released plenty of performance figures exceeding its design objective(s).

It's been said that the Raptor was designed to beat (and handily) any near peer adversary for the next 30 years. So if the PAK FA has variable inlets and gets the right engines, it might be capable of dash speeds in excess of Mach 2.5. We already know the Mig-31 is capable of Mach 2.8. I don't think the air force is going to re-design the thing to be able to chase down a Mach 2.5+ jet. I believe the capability is already there...


I may not know the definitive dash speed of the F-22 but as someone with aeronautical engineering education I can make informed hypothesis, and I can almost certainly rule out Mach 2.8. I've went over reasons for inlets, and materials, and the polycarbonate canopy, and very questionable benefit. Even from a drag point of view, assuming that your drag coefficient remains roughly the same at high supersonic (fairly reasonable assumption), your drag increases with velocity squared, so at Mach 2.8 you would have roughly double the drag you have at Mach 2, and nearly two and half times the drag at than Mach 1.8 which is about what the F-22 can reach without afterburners. When you factor in things like gradual loss of inlet efficiency as Mach number increases, and the fact that afterburning thrust is nowhere near double the dry thrust, you'll see why that high Mach number is so unlikely.

If you read about the history of the ATF, then you'll see after discussing trade studies with the Lockheed, Northrop, and other companies before the final RFP, the Air Force relaxed the original Mach 2.5 dash speed to Mach 2. Because you have to create so much additional complications and expense to go at a speed that a fighter will barely touch, plus potential compromises in stealth, that dash speed above Mach 2 makes no sense. Guess what, Sukhoi reached the same conclusion. No, the PAK FA isn't making Mach 2.5 either, not in its current form. The original requirement was Mach 2.35, which got reduced to Mach 2.15, and perhaps even lower to Mach 2. The reasons given were almost the exact same as the USAF, it adds unnecessary weight and potential compromises that it simply isn't worth it.

Even the best fighter aircraft isn't immune to physics, and relying on wishful thinking doesn't help. Also, no one, not even fighter pilots, is immune to hyperbole either. Sure the F-22 is fast. MiG-31 fast? No, and it doesn't even need to.
Last edited by disconnectedradical on 05 Jul 2017, 07:50, edited 1 time in total.
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jetblast16

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Unread post04 Jul 2017, 23:46

Perhaps a look into the past reveals something different (An oldie but goodie):

viewtopic.php?t=5474
Bringing BLAST since 2004...(In my opinion)
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mixelflick

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Unread post05 Jul 2017, 19:16

I may not know the definitive dash speed of the F-22 but as someone with aeronautical engineering education I can make informed hypothesis, and I can almost certainly rule out Mach 2.8. I've went over reasons for inlets, and materials, and the polycarbonate canopy, and very questionable benefit. Even from a drag point of view, assuming that your drag coefficient remains roughly the same at high supersonic (fairly reasonable assumption), your drag increases with velocity squared, so at Mach 2.8 you would have roughly double the drag you have at Mach 2, and nearly two and half times the drag at than Mach 1.8 which is about what the F-22 can reach without afterburners. When you factor in things like gradual loss of inlet efficiency as Mach number increases, and the fact that afterburning thrust is nowhere near double the dry thrust, you'll see why that high Mach number is so unlikely.

If you read about the history of the ATF, then you'll see after discussing trade studies with the Lockheed, Northrop, and other companies before the final RFP, the Air Force relaxed the original Mach 2.5 dash speed to Mach 2. Because you have to create so much additional complications and expense to go at a speed that a fighter will barely touch, plus potential compromises in stealth, that dash speed above Mach 2 makes no sense. Guess what, Sukhoi reached the same conclusion. No, the PAK FA isn't making Mach 2.5 either, not in its current form. The original requirement was Mach 2.35, which got reduced to Mach 2.15, and perhaps even lower to Mach 2. The reasons given were almost the exact same as the USAF, it adds unnecessary weight and potential compromises that it simply isn't worth it.

Even the best fighter aircraft isn't immune to physics, and relying on wishful thinking doesn't help. Also, no one, not even fighter pilots, is immune to hyperbole either. Sure the F-22 is fast. MiG-31 fast? No, and it doesn't even need to.[/quote]

The paragraph I highlighted made sense. Thanks..
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sferrin

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Unread post05 Jul 2017, 20:12

mixelflick wrote: Also, no one, not even fighter pilots, is immune to hyperbole either. Sure the F-22 is fast. MiG-31 fast? No, and it doesn't even need to.


What's more likely, that Paul Metz, Chief Test Pilot of both the YF-23 and F-22A, resorted to hyperbole on the record, or that the F-22 is actually almost as fast as an F-15?
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disconnectedradical

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Unread post05 Jul 2017, 21:14

sferrin wrote:
mixelflick wrote: Also, no one, not even fighter pilots, is immune to hyperbole either. Sure the F-22 is fast. MiG-31 fast? No, and it doesn't even need to.


What's more likely, that Paul Metz, Chief Test Pilot of both the YF-23 and F-22A, resorted to hyperbole on the record, or that the F-22 is actually almost as fast as an F-15?


F-22 reaching roughly F-15 speeds (around Mach 2.4) is plausible. Speeds like Mach 2.8 that has been suggested here, almost certainly not.
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Unread post06 Jul 2017, 14:33

sferrin wrote:
mixelflick wrote: Also, no one, not even fighter pilots, is immune to hyperbole either. Sure the F-22 is fast. MiG-31 fast? No, and it doesn't even need to.


What's more likely, that Paul Metz, Chief Test Pilot of both the YF-23 and F-22A, resorted to hyperbole on the record, or that the F-22 is actually almost as fast as an F-15?


Yeah, this is a fair point too. I do recall hearing it's "by far, the fastest aircraft we've got" - something to that effect. Sidebar: Is the F-15 really capable of Mach 2.5? Obviously, it'd need to be clean but I was just wondering.

It seems as if Mach 1.4/Mach 1.6 are the highest attributed combat airspeeds obtained to the F-15/F-14 respectively.
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