F-22 Speed = Mach 2.84 Calculations!!

Originally posted by FredT

Originally posted by TACHYON
Thats pretty fast, I thought it was Mach 2.5 tops. Anyway is the F-15 skin alumunimum or something and what about the raptors.

Titanium 64 (Ti-64) 36%
Thermoset Composites 24%
Aluminum (Al) 16%
Other Materials* 15%
Steel 6%
Titanium 62222 (Ti-62222) 3%
Thermoplastic Composites >1%
www.globalsecurity.org...

Considering that the F-22 is mostly titanium it will expand less due to thermal variations:

Aluminum:
Coefficient of linear thermal expansion [/K-1 multiplied by 10^6]: 23.1

Titanium:
Coefficient of linear thermal expansion [/K-1 multiplied by 10^6]: 8.6

[edit on 8-8-2004 by TACHYON]

Originally posted by TACHYON

Considering that the F-22 is mostly titanium it will expand less due to thermal variations:

- well there's some truth in that but the really significant point is what is and where is the titanium not a bald percentage figure.

If the government gave a speed of Mach 1.5-1.8, there had to be a good reason.

Maybe those are the speeds that he Raptor are more manueverable at.

Shattered OUT...

Actually the Air Force gave the Raptor an oficial speed of Mach 1.8+ and it is listed as a Mach 2 aircraft. The 1.5 is without afterburners. Plus wasn't the BlackBird made of mostly titanium like Raptor?

Without using afterburners it can cruise relatively economically between Mach 1.4 to Mach 1.72. Mach 1.4 is "generally" the point where an aircraft has full supersonic airflow over its entire body rather than the locallized supersonic flow that can happen depending on design anywhere beyend Mach 0.95 or so. The famous pics of the B-2 with that vapor cloud around it is a result of localized supersonic flow just because of wing curvature. True supersonic flight is when you're out of that dirty muddled airflow.....if you look at a transsonic drag profile you'll see that drag rises in a hump in the transsonic region and then actually reduces as it is fully supersonic at Mach 1.4 or so. So in essense it about as much power to go Mach 1.5 as it is to go Mach 1.2 or so. It varies from design to design where the drag rises, falls off and rises again in the supersonic regeime.

Originally posted by WestPoint23
Actually the Air Force gave the Raptor an oficial speed of Mach 1.8+ and it is listed as a Mach 2 aircraft. The 1.5 is without afterburners. Plus wasn't the BlackBird made of mostly titanium like Raptor?

The A-12/SR-71 was primarily Titanium, the Filets in the forward Chine was termoplastics. The Raptor is about 40% Titanium

Originally posted by TACHYON
Bill Sweetman has said that "the F-15 can attain its top speed only iwth a minimal weapons load and no external fuel, and most pilots never see 2.5 on the machmeter. The F-22 has plenty of thrust for Mach 2.5, but providing that performance would have demanded variable inlets and higher-temperature materials throughout the aircraft."

Alot of the speed and altitude records set by the F-15 were done with specialy modified "streak eagles" No weapons of conformal fuel cells, no paint for weight savings etc.

Originally posted by WestPoint23
............. Plus wasn't the BlackBird made of mostly titanium like Raptor?

- What I was getting at before Westy was that as well as the external 'skin' composition things like the materials/methods for fixing/bonding the skin to the internal structure and the internal structure itself all come into play in the realities of 'heat soaking'.

It's a very complex issue.

Originally posted by sminkeypinkey
What I was getting at before Westy was that as well as the external 'skin' composition things like the materials/methods for fixing/bonding the skin to the internal structure and the internal structure itself all come into play in the realities of 'heat soaking'.

Christ Sminkey two days in a row.

The blackbird used its huge low volitile fuel stores as a giant heat sink to reduce airframe temperatures. As special pumping system circulated fuel so that the hottest fuel was burned first.

Without an adequate ssytem to deal with all that heat buildup, the Raptor, even if it had enough thrust, would begin to suffer from the effects of heat well before it reached mach 2.8 or so.

Remeber all those speed quotes on planes is usually dash speed. The one convention fighter that can achieve Mach 2.8 is the Mig 25 (at a cost of burning out its turbines) and is constructed of stainless steel for heat resistance. The oly other Mach 3+ plane the XB-70 uses stainless steel honeycomb as well to help with heat resistance.

Originally posted by FredT
Christ Sminkey two days in a row.

- it must be a 'sign'!?

The blackbird used its huge low volitile fuel stores as a giant heat sink to reduce airframe temperatures. As special pumping system circulated fuel so that the hottest fuel was burned first.

Without an adequate ssytem to deal with all that heat buildup, the Raptor, even if it had enough thrust, would begin to suffer from the effects of heat well before it reached mach 2.8 or so.

- Yeah that's part of the 'trick' they have to use, Concorde did similar too.

Remeber all those speed quotes on planes is usually dash speed. The one convention fighter that can achieve Mach 2.8 is the Mig 25 (at a cost of burning out its turbines) and is constructed of stainless steel for heat resistance. The oly other Mach 3+ plane the XB-70 uses stainless steel honeycomb as well to help with heat resistance.

- Yeah I agree (). It seems mach 2.2 - 2.5 is a bit of a 'wall' until the materials, construction or maybe a bit of new tech comes along.

IMO it just isn't worth the candle to push things further.....rapid reaction is fine and all but what plausible scenario could there be that would call for more speed anyway (given the current global surveillance/early warning capacity) versus the costs/capability reduction it would impose?

Originally posted by sminkeypinkey
IMO it just isn't worth the candle to push things further.....rapid reaction is fine and all but what plausible scenario could there be that would call for more speed anyway (given the current global surveillance/early warning capacity) versus the costs/capability reduction it would impose?

I think rapid global strike will be the cornerstone of US strategy in the future. As the avalibilty of oversea bases declines, the ability to base Mach 6+ aircraft int he US and strike targets all over the world rapidly will be of great benifit. Thats why the Non nuclear ICBM makes sence. push a button, 30 minutes later, target hit.

Originally posted by FredT
I think rapid global strike will be the cornerstone of US strategy in the future.

- True. It pretty much is now, isn't it?

As the avalibilty of oversea bases declines,

- I can see what you mean but I don't see the US leaving in sufficient areas of the globe to really make that much difference in the foreseeable future.

In any case I think (hope) the current US indifference (amongst some in the US, not all) to whether they are isolated or not is a temporary phenomenon.

the ability to base Mach 6+ aircraft int he US and strike targets all over the world rapidly will be of great benifit.

- Maybe. But then again the handful (like the B2) that that 'policy' would require would be so specialist and non-typical of the general USAF.....why bother with such a demanding and difficult aircraft?

Thats why the Non nuclear ICBM makes sence. push a button, 30 minutes later, target hit.

- This makes far more sense if response speed is your top priority.

I can't see why there would be such a need for such an aircraft.

With several carrier groups around the world and the overseas deployment such as it is what is likely to be so unseen by surveillance (and all the rest) that makes such a vast investment so necessary - particularly when the non-nuclear missile option is now accurate enough to be feasible?

Recall was always the big deal before but given the stated desire for speed (and the availablity and quality of recon from other sources) surely that becomes redundant? What could a manned ultra-highspeed plane see that the satellite couldn't?

Recall was always the big deal before but given the stated desire for speed (and the availablity and quality of recon from other sources) surely that becomes redundant? What could a manned ultra-highspeed plane see that the satellite couldn't?

Satellite flight paths can be found and all you have to do is throw some cammo nets until the satellite leaves your area. But a Hypersonic stealth plane can be a surprise it comes out of nowhere and zooms by at Mach 7 snapping photos before you even have a chance to move.

Maybe. But then again the handful (like the B2) that that 'policy' would require would be so specialist and non-typical of the general USAF.....why bother with such a demanding and difficult aircraft?

No I think if the US has 20 Hypersonic stealth planes that is enough we don't need 400,20 will do the job. Having some is better than having nothing. Plus the US always pushes the envelope we never stay with one thing to long or others could catch up.

Originally posted by WestPoint23
Satellite flight paths can be found and all you have to do is throw some cammo nets until the satellite leaves your area.

- That's only partially true Westy. In a serious situation tensions would trigger the altering of flight paths and probably even a few new satellites going up (secretly/covertly).

In any case do you really think any country/region of any significance isn't covered to some degree now with geostationary observation? They are where the people are.....which is where you want them.

.....and with observation across the entire spectrum 'cammo nets' are a tad insufficient to cover all but the most cursory glance.

But a Hypersonic stealth plane can be a surprise it comes out of nowhere and zooms by at Mach 7 snapping photos before you even have a chance to move.

- Well if you say so. I can't see it myself.

A 'plane' at mach 7 within the atmosphere at high or medium altitude is going to trigger every IR detector on the globe (even if they can do something about the noise) and at low altitude is, frankly, so unlikely as to be impossible....in any case even a rudimentary sound homing device couldn't fail to lock and hit it.

I think if the US has 20 Hypersonic stealth planes

- LOL, you really want - and need - to believe this stuff, huh?

Having some is better than having nothing.

- If they have no real plausible functional role what on earth is 'better' about it?

Plus the US always pushes the envelope we never stay with one thing to long or others could catch up.

- What is this Westy? God bless America broadcasting? Should we have a tear in ort eye right now and be stood up saluting at the thought of what awesome military weeners er, I mean might, the US military might have?!

Rather than concentrating on the wildest flights of 'Buck Rogers' fantasy you might start thinking about the practicalities a little more.

If they have no real plausible functional role what on earth is 'better' about it?

They do have a role to play reconnaissance at a moments notice.

LOL, you really want - and need - to believe this stuff, huh?

You don�t know what we have in our black projects neither do I we cant rule it out.

A 'plane' at mach 7 within the atmosphere at high or medium altitude is going to trigger every IR detector on the globe (even if they can do something about the noise) and at low altitude is, frankly, so unlikely as to be impossible

Nope the Black bird flew at 85.00o-100.000 feet. A hypersonic plane with a ramjet engine would fly higher than that and closer to space since a ramjet can work fine at those altitudes. At those heights no IR sensor is going to have an easy time picking you up.

Originally posted by sminkeypinkey
- That's only partially true Westy. In a serious situation tensions would trigger the altering of flight paths and probably even a few new satellites going up (secretly/covertly).

You can only alter a satelites trajectory a little. And you would burn up its manuvering fuel pretty quickly. Once that happens, that lacrosse bird is just about useless. Most countries do not have backups ready to go as far as I we know. The really high end birst are pricey to say the least.

I'll see if I can find out for you pretty soon about the speed....but I don't talk to my dad that much, hehe....

That's likely something he'd gloat about, and then say "oops..."

Most countries do not have backups ready to go as far as I we know. The really high end birst are pricey to say the least.

It's a bit of a pain to launch a military spy satellite compared to civilian comms satellites because the spy satellites use very heavy mirrors. I would guess it takes a lot of planning to launch one into the correct orbit. Hence I doubt any country has spy satellites sitting on a launch pad ready to go.

Originally posted by Cjwinnit

It's a bit of a pain to launch a military spy satellite compared to civilian comms satellites because the spy satellites use very heavy mirrors. I would guess it takes a lot of planning to launch one into the correct orbit. Hence I doubt any country has spy satellites sitting on a launch pad ready to go.

- I have no doubt that no-one has a satellite or two on a pad anywhere but I would bet a lot of money that there are one or two warehoused in reserve in a clean cocoon around the place somewhere. Ready to go within a few days if needed.

IMO the idea that a situation could or would develop any faster than that with no warning or notice of any kind is just not feasible.....

....and as I said the coverage as it is is pretty comprehensive at the moment.

Originally posted by sminkeypinkey
IMO the idea that a situation could or would develop any faster than that with no warning or notice of any kind is just not feasible.....

True. Most events take a few weeks minimum to play out before all-out conflict starts, it just depends on how good your intelligence is on how big a warning you get.