Scramjets

What do folks know about Scramjet technology? How long will it take to put this technology to practical use?

they've recently had a successful hypersonic missile test, right?

don't know why it's taking so long. maybe due to failures or something.

been waiting for a long time.

http://en.wikipedia.org/wiki/National_aerospace_plane

The X-30 National Aero-Space Plane (NASP) was an attempt by the United States to create a viable single-stage-to-orbit (SSTO) spacecraft. The project was cancelled prior to the first craft being built.

NASP originated from a Defense Advanced Research Projects Agency (DARPA) project called Copper Canyon that ran from 1982 to 1985. In his 1986 State of the Union address, President Ronald Reagan called for "...a new Orient Express that could, by the end of the next decade, take off from Dulles Airport, accelerate up to 25 times the speed of sound, attaining low earth orbit or flying to Tokyo within two hours."

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The X-30 configuration was basically a highly integrated engine. The shovel shaped forward fuselage generated a shock wave to compress air before it entered the engine. The aft fuselage formed an integrated nozzle to expand the exhaust. The engine in between was intended to be a scramjet engine. At the time, a scramjet engine had never been successfully tested.

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http://en.wikipedia.org/wiki/Scramjet

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Projections for the top speed of a scramjet engine (without additional oxidiser input) vary between Mach 12 and Mach 24 (orbital velocity). The X-30 research gave Mach 17 due to combustion rate issues. In contrast, the fastest conventional air-breathing, manned vehicles, such as the U.S. Air Force SR-71 Blackbird, achieve approximately Mach 3.4 and rockets from the Apollo Program achieved Mach 30+.

Scramjets have weight and complexity issues that must be considered. While very short suborbital scramjet test flights have been performed, no flown scramjet has ever been designed to survive a flight test. The viability of scramjet vehicles is hotly contested in aerospace and space vehicle circles, in part because many of the parameters which would eventually define the efficiency of such a vehicle remain uncertain. This has led to grandiose claims from both sides, which have been intensified by the large amount of funding involved in any hypersonic testing. Some notable aerospace commentators such as Henry Spencer and Jim Oberg have gone so far as calling orbital scramjets "the hardest way to reach orbit",[citation needed] or even "scamjets"[citation needed] due to the extreme technical challenges involved. Major, well-funded projects, like the X-30 were cancelled before producing any working hardware.

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http://en.wikipedia.org/wiki/Scramjet#Recent_progress

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On May 27, 2010, NASA and the United States Air Force successfully flew the X-51A Waverider for approximately 200 seconds at Mach 5, setting a new world record hypersonic airspeed. The Waverider flew autonomously before losing acceleration for an unknown reason and destroying itself as planned. The test was declared a success. The X-51A was carried aboard a B-52, accelerated to Mach 4.5 via a solid rocket booster, and then ignited the Pratt & Whitney Rocketdyne scramjet engine to reach Mach 5 at 70,000 feet.[17]

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i don't see it happening anytime soon except possibly for missiles, and even that's a stretch.

Originally posted by zeeblebot
i don't see it happening anytime soon except possibly for missiles, and even that's a stretch.

this is likely to be a weaponized technology in the short term -- cruise missiles might have unlimited range and could be flown by remote control, arriving on target much sooner than present rocket motors.

However, the long term potential is for hypersonic passenger aircraft, although hypersonic military transports will be the first to be developed, probably.

The other end of the spectrum is also moving ahead -- a trilobe airship that can serve as a long term recon platform is in prototype testing by Lockheed.

I'd like the 6-seat model with the large cargo bay and a dog run, please.

I can't think of a better RV than an airship that can land anywhere without a ground crew, etc.

The biggest problem technically is the short amount of time you get to ignite the propellant. It is on the order of 1 or 2 milliseconds or less, most of the early failures were due to flameouts. Think about striking a match in a tornado.

Originally posted by Scriabin
this is likely to be a weaponized technology in the short term -- cruise missiles might have unlimited range and could be flown by remote control, arriving on target much sooner than present rocket motors.

However, the long term potential is for hypersonic passenger aircraft, although hypersonic military transports will be the first to be developed, prob ...[text shortened]... can't think of a better RV than an airship that can land anywhere without a ground crew, etc.

how is it going to land anywhere? if scramjets only operate at high speeds, you'd need an extra set of non-scramjet engines just to boost to your cruising speed, and also to reduce to landing speed. penalty weight.

Originally posted by zeeblebot
how is it going to land anywhere? if scramjets only operate at high speeds, you'd need an extra set of non-scramjet engines just to boost to your cruising speed, and also to reduce to landing speed. penalty weight.

They would presumably have jet engines onboard also to get you up to scramjet speed and have some fuel left over after you re-enter the atmosphere. Also, the space shuttle manages to get back to Earth without power, so gliding is an option.

ok, i missed the part where Scriabin said "airship". that changes the feasibility of "land anywhere without a ground crew" quite a bit 🙂.