F-22 Raptor speed

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

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Unread post06 Jul 2017, 14:55

mixelflick wrote:
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.


The F-15 can only really get to just below Mach 2.5 at about 50,000 ft IIRC. Any lower and it drops to Mach 2.3 or so.
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sferrin

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Unread post06 Jul 2017, 15:04

tacf-x wrote:The F-15 can only really get to just below Mach 2.5 at about 50,000 ft IIRC. Any lower and it drops to Mach 2.3 or so.


Mach 2.5 is always the maximum given. Mach 2.7 was the original requirement but it was dropped to Mach 2.5 in order to get the "bubble canopy". (The original concept had a Tomcat-like windscreen.) Can it ACTUALLY do Mach 2.5? Don't know. Where have you heard it couldn't?
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Unread post06 Jul 2017, 16:17

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


I can't place the source, but I recall a USAF General saying that the F-15 has gone > mach1.2 in combat ~"maybe a handful of times". This is one of the reason why they did not spec the F-35 above mach 1.6.
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Unread post06 Jul 2017, 22:14

Check page 346 (A9-4C) and beyond : http://www.avialogs.com/viewer/avialogs ... hp?id=3704

When clean and with an engine trim of 97.7%, the F100-PW-100 powered F-15A/C has a top speed a bit below Mach 2.25 on a standard day. A lightly loaded one (4 AIM-7, 4 AIM-9 and the centerline pylon), is a bit above Mach 1.8 in the same conditions.
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disconnectedradical

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Unread post06 Jul 2017, 22:41

sferrin wrote:
tacf-x wrote:The F-15 can only really get to just below Mach 2.5 at about 50,000 ft IIRC. Any lower and it drops to Mach 2.3 or so.


Mach 2.5 is always the maximum given. Mach 2.7 was the original requirement but it was dropped to Mach 2.5 in order to get the "bubble canopy". (The original concept had a Tomcat-like windscreen.) Can it ACTUALLY do Mach 2.5? Don't know. Where have you heard it couldn't?


On a standard day atmosphere conditions, no it can't. A clean F-15C with no adapters or launchers and with F100-PW-220 tops out at Mach 2.45. It can go over Mach 2.5 if the air temperature is 10 degrees colder than standard day. If you add launchers and adapters it drops down to Mach 2.35 on standard day, and adding weapons will just make it go lower.
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Unread post08 Jul 2017, 16:25

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


I can't place the source, but I recall a USAF General saying that the F-15 has gone > mach1.2 in combat ~"maybe a handful of times". This is one of the reason why they did not spec the F-35 above mach 1.6.


Understand, why pay for the capability (greater than 1.6) if you're not going to use it?

As for the maximum quoted mach # for the F-15, I think it was Dozer in Bosnia vs. the Mig-29 where I read he hit Mach 1.4. As for the Tomcat, there's an Iranian pilot on youtube claiming he hit Mach 1.6 chasing a Foxbat. I suppose the USAF finally come to grips with "speed isn't life" only recently (after years of reviewing the Desert Storm/Iraq 2 and Bosnia air wars).

Will we see a fighter capable of Mach 3 ever again? Yep. Although it will almost certainly be Russia's Mig-31 replacement, assuming that makes it off the drawing boards...
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Unread post08 Jul 2017, 19:30

disconnectedradical wrote:
sferrin wrote:
tacf-x wrote:The F-15 can only really get to just below Mach 2.5 at about 50,000 ft IIRC. Any lower and it drops to Mach 2.3 or so.


Mach 2.5 is always the maximum given. Mach 2.7 was the original requirement but it was dropped to Mach 2.5 in order to get the "bubble canopy". (The original concept had a Tomcat-like windscreen.) Can it ACTUALLY do Mach 2.5? Don't know. Where have you heard it couldn't?


On a standard day atmosphere conditions, no it can't. A clean F-15C with no adapters or launchers and with F100-PW-220 tops out at Mach 2.45. It can go over Mach 2.5 if the air temperature is 10 degrees colder than standard day. If you add launchers and adapters it drops down to Mach 2.35 on standard day, and adding weapons will just make it go lower.


The original -100 engine had a bit more power than a -220. The -229 certainly does. The F-15C/D also gained weight over the A/B (see page 1-2 of your document). The graphs on pages 5-7 and 5-8 both show 1 minute transients of Mach 2.5 are allowed.

Capture.PNG


And from, "F-15 Eagle Origins and Development" page 30:

Capture2.PNG
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Unread post08 Jul 2017, 20:01

sferrin has it. The original F-15A was pretty fast, like around 800 knots CAS fast at 36,000 feet, completely clean. That's 1,600+ mph.
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Unread post09 Jul 2017, 02:13

sferrin wrote:The original -100 engine had a bit more power than a -220.

Sea Level Static Uninstalled Thrust, sure. The -220 had more Dynamic thrust at most operational conditions.
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Unread post09 Jul 2017, 18:16

Also, the removal of the exhaust nozzle petals resulted in an aerodynamic drag increase, over the original F-15A.
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Unread post16 Aug 2017, 23:58

sferrin wrote:
tacf-x wrote:The F-15 can only really get to just below Mach 2.5 at about 50,000 ft IIRC. Any lower and it drops to Mach 2.3 or so.


Mach 2.5 is always the maximum given. Mach 2.7 was the original requirement but it was dropped to Mach 2.5 in order to get the "bubble canopy". (The original concept had a Tomcat-like windscreen.) Can it ACTUALLY do Mach 2.5? Don't know. Where have you heard it couldn't?

Wouldn't the original requirement come from the F-15 being designed in part because of the Mig -25 Foxbat?

So , there was a worry the Eagle couldn't catch a Foxbat in a chase and might need to play that game

and funny enough ,look what eventually actually happened after it was developed- Foxbats outrunning Eagles....(granted not too often)

(I assume the Foxhound would have a harder time replicating the feat, and for what it's worth, suspect the Foxbat would manage to catch a running Foxhound, and that a F-22 would be the plane of choice to catch a going-for-broke Foxbat/FoxHound/Blackbird trying to get away over say a clean F-15 with a minimal number of AMRAAMS if you had a presumed (or real, for that matter) Mach 3 target running around seemingly untouchable to weapons that all run out of initial fuel and can't play catch-up while gliding.

I've seen many hold fast that a Eagle however, is what you'd want to try to get a target running around like that. IF we ever see that proposed Mig-41 or they cough out a Mach 3 Blackjack - we'll see. Mach 2.5 or 2.8, the Raptor's internal bay should be a benefit against a Eagle also trying to catch up to the same Mach 3 foe.

That's an interesting prediction that we will see another Mach 3 fighter for sure. I actually am of the same mind, but....suspect it will be a long time- perhaps until some country with Foxbats (or maybe Foxhounds) starts using them in a way that we see more of them outrunning other planes as the one that nabbed a Hornet did.
Probably more likely to see a Mach 3 fighter than Bomber I suspect.

That note on the origins of the Eagle notes increased Titanium would have been needed- I guess that indicates significant heating occurs even before the Mach 3 zone.
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Unread post17 Aug 2017, 01:37

High speed supersonic fghter airplanes were originally intended to intercept high speed supersonic bombers at short range on short notice but when all the supersonic bombers got cancelled in lieu of ICBM's the need for mach 3 bombers dissolved.

Also the amount of fuel required to do a mach two plus supersonic dash isn't really worth the effort since drag is the square of the velocity and thrust must equal or exceed the drag the fighter goes bingo fuel to fast to make it operationally useful. For instance the combat radius of the mig 25 was only 300 KM which when compared to some thing like the Patriot missile system is relatively comparable given the required mission.

With that being said it is easy to see why the USAF dropped the mach 2 requirement for the F-22 and F-35 as it just wasn't useful. Instead of a high ultimtate speed specification of mach 2 it was operationally realized that a high average speed in realm of mach 1.6 to mach 1.8 was more then adequate given the operational historical data of how fourth genration fighers were actually used in combat configuration.
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Unread post17 Aug 2017, 05:01

alloycowboy wrote:High speed supersonic fghter airplanes were originally intended to intercept high speed supersonic bombers at short range on short notice but when all the supersonic bombers got cancelled in lieu of ICBM's the need for mach 3 bombers dissolved.

Also the amount of fuel required to do a mach two plus supersonic dash isn't really worth the effort since drag is the square of the velocity and thrust must equal or exceed the drag the fighter goes bingo fuel to fast to make it operationally useful. For instance the combat radius of the mig 25 was only 300 KM which when compared to some thing like the Patriot missile system is relatively comparable given the required mission.

With that being said it is easy to see why the USAF dropped the mach 2 requirement for the F-22 and F-35 as it just wasn't useful. Instead of a high ultimtate speed specification of mach 2 it was operationally realized that a high average speed in realm of mach 1.6 to mach 1.8 was more then adequate given the operational historical data of how fourth genration fighers were actually used in combat configuration.


Not only that but the Mig-25's engines were over-optimized strictly for high speed flight. The engines consisted of a low OPR single-spool turbine which meant fuel consumption at low speeds and altitudes was going to be crap as well. The reason why low compressor pressure ratios are desired for high-speed flight is because all you really need for compression at ~Mach 3 is the ram compression from the intake ramps, shockwaves and diffuser. The turbomachinery would only increase the likelihood of overtemping the turbine inlet at those speeds.
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Unread post17 Aug 2017, 15:38

OK... does anyone know the top speed (clean) of an F-15 with those bigger, more powerful GE motors?

They all seem to be Strike Eagle derivatives, but assuming you take the FAST packs/CFT's and everything else off....? Any guesses vs. the Pratt and Whitney birds?
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Unread post17 Aug 2017, 15:41

mixelflick wrote:OK... does anyone know the top speed (clean) of an F-15 with those bigger, more powerful GE motors?


The P&W -229s are as powerful as the F110s. (I'd think they'd do even better at high altitude/speed.)
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