DARPA cancels Blackswift

First off hypersonic and supersonic are different. Hypersonic IS speed related. Mach 1-5 is supersonic, Mach 5+ is hypersonic. There IS a difference.

Secondly, the fact that we're selling the F-35 to other countries means nothing other than the fact that we wanted to help defer the costs of the project some. We don't have ANY yet, as there are two flying, and both are still prototypes. It hasn't even hovered yet with the F-35B. The F-35C is ALMOST finished but it has a ways to go yet before it even flies the first time. No one is getting ANY of the for several more years yet.

Last, "multiple, nearly undetected sorties", you would need almost all of the F-35s that the US is getting to have enough to make a huge difference in a theater in the bombing role. One of the huge drawbacks to the F-117 was that it only carried two bombs. I don't care how stealthy it is, two bombs isn't enough to make it super important. Yeah, you can hit heavily defended targets and maybe succeed in a decapitation strike, but what's the point in using the F-35 as a bomber, when we have the B-2. For the F-35 to be useful in a bombing role it's going to have to fly out of bases near their targets. If we wanted to hit Iran let's say, they'd have to fly out of Iraq or Afghanistan. Otherwise, they would have to have massive tanker support, and fly so long that the pilots would be exhausted before they even got NEAR their targets.

So even if they ARE stealthy, all your enemy has to do is have people sitting around watching the runways to show take off time, and that they took off, and they know they're coming. They might not be able to SEE them coming (which they probably still CAN see them somewhat) but they can take steps to prevent a decapitation strike.

reply to post by Zaphod58


Do the math, it's internal fuel capacity is 2.5X that of the F-16 while its internal weapons systems ALONE reduce the drag of the F-16 by half. Not to mention its stealth design.

Yet its estimated range is speculated at 600km, even though its actual range is classified.

Originally posted by Jay-in-AR
The only difference between the known mach 3.5 speeds and the rumoured mach 5 speeds are just how quickly can you outrun any missle. After mach 3.5, it is moot. Pretty soon, you are talking about unmanned vehicles.

There are HUGE differences besides that. The SR-71 couldn't go much faster than Mach 3.2 because of heating. As your speed increases, your heat increases monumentally. The faster you go, the higher the temperature. This means that you're limited by the materials used, and the shape of the airframe. It's a lot more complex than you make it out to be.

reply to post by Jay-in-AR


And that proves what exactly? The fact that it carries more internal fuel means that it carries fewer weapons. They have to take the room for the fuel from somewhere. The F-35B has a smaller weapons bay because of the lift fan. So what if the range is longer than the F-16, that proves nothing except that it can fly farther.

You're not going to launch a strike from the US using F-35s, because they'd still have to fly for hours to get anywhere, and by the time they did, the pilots legs wouldn't be talking to the rest of them. All that means is that they'd only have to refuel twice, instead of three times in theater.

May I ask you what your definition of hypersonic is? And no, I don't mean, that which moves at a speed greater than mach 5.

Originally posted by Jay-in-AR
Do the math, it's internal fuel capacity is 2.5X that of the F-16 while its internal weapons systems ALONE reduce the drag of the F-16 by half. Not to mention its stealth design.

Are you confusing Combat radius with maximum range? There is no way that the US would stage F-35's from the CONUS like they do the B-2's. I mean in theory you could with tanker support but it would be pointless.

But apparently we have enough of them to sell them to foreign nations now. Plus, they're stealth. Multiple, nearly undetected sorties putting smart payloads on any target, anywhere on the planet.

The plane is barely in LRIP right now and its been a collaborative effort among several nations so its not a question of enough to sell yet. Its not even out of flight test let alone squadron service and the B and C variants have not even flown yet if im not mistaken.

As Zaphod notes, hypersonic speeds is not a question of strapping on a bigger engine. Heat is a huge issue that has to be dealt with. The SR-71's / A-12 had the engines needed to go faster but thier airframe could only cope with the heating of mach 3-2 to 3.35 anything above that would and could seriously damage the airframe to the point of failure.


[edit on 10/13/08 by FredT]

Originally posted by Jay-in-AR
May I ask you what your definition of hypersonic is? And no, I don't mean, that which moves at a speed greater than mach 5.

But thats exactly what hypersonic means

In aerodynamics, hypersonic speeds are speeds that are highly supersonic. Since the 1970s, the term has generally been assumed to refer to speeds of Mach 5 (5 times the speed of sound) and above. The hypersonic regime is a subset of the supersonic regime.en.wikipedia.org...

reply to post by Jay-in-AR


What do you think hypersonic is? It's a SPEED. The generally accepted speed is Mach 5, by just about everyone in the aviation industry. That includes engineers and designers.

Nothing that currently flies that we know of is hypersonic, because it requires a ramjet or scramjet to fly that fast. Ramjets don't work a lower than about Mach 3-4. Even the X-43 which hit Mach 10 required a Pegasus booster to get it up to Mach 5 before the engine worked.

The definitions are debatable on the terms of is it the speed of the craft moving, or the airflow around it.

Hypersonic can be determined to be that which the airflow intake is overwhelmed by the airflow around the craft itself. Not necessarily Mach 5.

Regardless the ACTUAL speed of the craft, barriers can be broken prematurely, or delayed, via airflow.

[edit on 13-10-2008 by Jay-in-AR]

Speed definitions are made by the speed of the aircraft. Saying an SR-71 can fly at Mach 3.2 doesn't mean that the airflow is going Mach 3.2, it means the AIRCRAFT is flying at Mach 3.2. Speed definitions have nothing to do with airflow speed, they have to do with AIRCRAFT speed.

reply to post by Jay-in-AR


Can it? By whom? And is their opinion worth a light when it disagrees with the ENTIRE aeropace industry of the world, which ought to know what it is talking about.

every definition I can find comes out like this;

hypersonic ; Adjective
having a speed of at least five times the speed of sound

And even if you take your home made personal definition, in what way does it apply to the F-35?

To me, this means nearly nothing, which is part of the point. In any event, the speeds are tremendous, but in terms applicable to my own EYEBALL, it would be airspeed vs. ground speed.

In my car I can literally outrun a plane to a destination at interstate speeds while the plane is moving at an airspeed of 140+ mph.

But now you are doing what is known in my locality as 'talking bollocks'.

But the entire essense of the "sonic boom" is the airspeed around the craft!


Eh, I'll leave it at this. Supersonic speed is less of a requirement into a 40mph headwind.

[edit on 13-10-2008 by Jay-in-AR]

You would have to go some to find a 3,500mph headwind though, which is what you'd need to make your 'argument', such as it is, stand up. Which it doesn't

It's going to be the same speed, whether you have a headwind or not, unless you're at a different altitude. The higher the altitude the lower the speed. You are talking about INDICATED airspeed vs TRUE airspeed. The two of them are different, and one is affected by headwinds and tailwinds. Or as my father liked to put it, you have airspeed, and you have groundspeed.

Not really.
The FA-22 and 35 have a classified top speed. They are supersonic CRUISERS.

My point was that at those speeds, you don't need much else. Especially when you combine their stealth. Any faster and you start dealing with the inability of any surface to air missile catching them. After that, you are dealing with reconaissance only missions. Straight flights. Any trajectory changes and you are talking about G-forces that can crush a human. (Remember the "heating" talk)...

Speaking of that, when is some genius going to put a gyrating cockpit in an aircraft (or have they already?)

The point about the SR-72 was that it is probably black listed now. Hell, it was before 1 month ago.

Not only that, but if we have an admitted F-35 project, we have it developed. It has been black for awhile now.

[edit on 13-10-2008 by Jay-in-AR]

reply to post by Zaphod58


Very true, like I said, airspeed vs. ground speed.

...

And no, you don't need a 3,500 mph headwind. Just a 40mph headwind will alter the speed at which a sonic boom is achieved.

The F-35????? Black??????? Where the heck do you get that idea? The F-35 has been transparent the entire time, with the exception of some of the stealth aspects. But the design has gone through the competition, development, contract award, and testing stages, and has been followed the entire time. What do you think, that we have hidden wings of F-35s that NO ONE has seen flying around somewhere? There are TWO F-35s flying right now, and both have been accounted for from the time they rolled off the line.

As to your speed issue, it would take a LOT more for them to go from supersonic to hypersonic. As for the G forces, have you ever bothered to read anything about SR-71 missions? There is no way that they could turn at ANY type of force, or it would have torn the airframe apart. That's why even at Mach 3 it took them several hundred, if not several thousand miles to make a turn.

reply to post by Jay-in-AR


Except that the speed of a sonic boom doesn't change, except with pressure. It doesn't change with a headwind, or a tailwind. What changes is the INDICATED airspeed that they go supersonic. The TRUE airspeed stays the same, no matter what the outside conditions are.