Mach 4 or 5

[Rocketscience101]

I've been doing research into future aircraft that could achieve incredible speeds. I've discovered the Sr 72, which appears to be unmanned, but I would like to see a manned aircraft traveling at around mach 4. Could somebody look for something like that?

video on the sr 72:

[DaveofDefeat]

http://en.wikipedia.org/wiki/North_American_X-15

[moogoob]

What about the rumored Aurora spy plane? Has that been declassified yet?

[Nibb31]

What about the rumored Aurora spy plane? Has that been declassified yet?

There's nothing to declassify. If there was a super-secret spy plane called Aurora, you wouldn't know about it.

Edited December 28, 2014 by Nibb31

[Meecrob]

What about the rumored Aurora spy plane? Has that been declassified yet?

Ben Rich (Chief engineer of the F-117) mentioned in his book that when Lockheed was bidding on the B-2 bomber program that they received money from the government. On a program as top secret as the B-2, you don't just write "TOP SECRET STEALTH BOMBER" in the accounting books, so they chose to call it "Aurora." Its been a few years since I've read it so I'm not sure if this was in Lockheed's or the government's ledgers, but I am leaning heavily towards the government's. Of course you can just say the men in black made all that up and told Ben Rich to say it, but I think Occam's Razor comes into play here.

Edit for content: Rocketscience101 - There are no current manned aircraft with cruise speed in the range you are asking about. I think the reason for this is that we don't need them to operate in that speed range. Sure, it would be nice to do NYC to London in less than 2 hours. but would you pay $500,000 a ticket? Concorde topped out just over mach 2 because when you go faster, the skin friction increases so much that traditional aluminum loses its strength. Then what about the (expensive) titanium SR-71 you ask? Back when it was being developed, spy satellites didn't exist and atmospheric recon had to be done. To go to mach 3, they chose to use titanium, then realized they had no tools that were strong enough to use with it. They literally created their own titanium milling procedures and made all their parts themselves. Now, the SR-71 was actually on budget if I recall, but it was considered such an asset to national security and the Russian Threat that money was not an object in its construction.

Overall, unless there is a significant breakthrough, the physics of pushing something that fast while in atmosphere loses out to slowing down, or biting the bullet and going (sub) orbital and accepting the added complexity for vastly improved performance.

Edited December 28, 2014 by Meecrob

[Streetwind]

A derivative of Skylon's SABRE engines could be feasible for use on an all-atmospheric passenger jet called LAPCAT-A2. It would be capable of flying at up to Mach 5, making the trip from London to Sydney in roughly four hours.

Said engine derivative is currently carrying the codename "Scimitar" (yes, really) and is expected to do away with the closed cycle capability of the SABRE, but in return gain a high-bypass mode for fuel efficient subsonic flight - to avoid hammering population centers with incessant sonic booms on every arrival, departure or overflight.

More info: http://www.reactionengines.co.uk/lapcat.html

Note: this is a theoretical concept study at this point. I would expect Reaction Engines Ltd. to tackle this project after Skylon makes it to space. Which is probably still at least 6 years away, most likely more.

[moogoob]

Thanks for the info - I recall hearing about the Aurora-B2 connection some time a while ago. Still, there might be a plane or three that IS classified but still in use. How long did the SR-71 fly for before being officially announced?

Of course, that was the era where spy planes were actually useful; spy satellites had to shoot film canisters in reentry capsules just to recover high-res images and planes could simply, well, land and have their film developed without risking it being intercepted. Maybe there's just no need for top-secret super-fast planes any more?

[PakledHostage]

Of course, that was the era where spy planes were actually useful; spy satellites had to shoot film canisters in reentry capsules just to recover high-res images and planes could simply, well, land and have their film developed without risking it being intercepted. Maybe there's just no need for top-secret super-fast planes any more?

IIRC, that was the justification for retiring the SR-71fleet back in the early '90s.

[Kryten]

How long did the SR-71 fly for before being officially announced?

-5 months. LBJ publicly announced the programme after being accused of letting the US fall behind technologically in the 1964 presidential campaign.

[bdito]

X-15. The fastest manned plane ever. Got up to mach 6 and actually left earth's atmosphere. And that in the 60's.

[Meecrob]

A derivative of Skylon's SABRE engines could be feasible for use on an all-atmospheric passenger jet called LAPCAT-A2.

~snip~

This is the type of breakthrough I was thinking of when I previously replied. In a sense, we are very similar to being back in the late 20's-early 30's trying to break the sound barrier. Back then we needed new engines, aerodynamics, engineering...well pretty much a level up in all our technology at the time. These things were improved upon because there was a need for them in order to achieve what we wanted to do in fields other than aviation (IE commercial/military, and not NACA/NASA experimental flight). Currently, I don't see a need, but I do like to think that is because the people who are developing the technology aren't playing their cards yet.