NASA dusts off X15-successor rocket hyperplanes NASA has dusted off a pair of prototype hypersonic rocket-planes it has had lying around since the 1990s with a view to getting them flying. The X-34 project was cancelled in 2001 "for both technical and budgetary reasons", but now the mothballed rocket ships are being checked out to see if they are "potentially viable as flight …
Specifically, 1990's cutting-edge tech from NASA.
Sounds like an admission that they've done fuck-all of any consequence in the rocket science department for the last 10 years, if brushing the dust off these hanger queens and flying them is supposed to prove anything useful.
The X-33 engine program was cancelled when its fuel tanks kept fracturing when filled with cryogenic hydrogen and/or oxygen. The fuel tanks were constructed with composite materials to help reduce lift-off mass.
Apparently, the composites that were tried became exceedingly brittle at cryotemps, and their lack of elasticity at very low temperatures made it difficult to isolate the tanks from vibration transmitted from the engines by the fuel/oxidiser feed lines.
This vibration, combined with the lack of required elasticity, would cause the tanks to become friable along the composites' "grain", much is the same way that it's easier to split a log into firewood along the wood-grain, as opposed to across it...
"I'd like to know why they discontinued development of the X33 linear aerospike motor. "
There were hopes its development would be continued after the X33 went down the pan but since the X33 *was* the only vehicle whose geometry matched the size and shape of the engine it didn't happen.
"It seemed to have all the right answers. for an uncomplicated rocket motor"
It's "simplicity" is only relative to something like the SSME. You're looking at an engine with 10 thrust chambers designed to eliminated gimbal steering by differential throttling. This needs faster valves *combined* with a fast responding thrust chamber design that remains *stable* to substantial throttling. . But it's pretty impressive for something in store since about 1974.
Was NASA's attempt to demonstrate that while they had destroyed the DC-X through careless ground handling they *could* build a vehicle and demonstrate the pre-cursor of a true Single Stage To Orbit transport.
Note a *true* X programme aims to demonstrate *capability* in the simplest possible way. It's *key* requirements are very short and direct. build it, test it to near destruction (or sometimes beyond) and use the data to build the *real* vehicles of the future. You might recall the X1's mission. Exceed the speed of sound without falling apart and/or killing the pilot. *Everything* else is negotiable.
NASA management types then proceeded to tag on a load of unnecessary requirements *including* that the winning contender stump up a chunk of cash into the design to be developed *after* X33 had proved the concept.
Lockmart won with the most complicated, least tested (indeed the original shaped failed in later wind tunnel tests *after* they won the contract) design with the *most* amount of bleeding edge tech *coupled* with the highest planned cash injection for their follow on vehicle design.
Why?
Because they had *no* plans to get to a follow on vehicle.
They had (and as ULA still have) a *very* substantial expendable launch business. Hoovering up *all* the available money choked off both North American(the people who built the shuttle) and McDonald Douglas (The people who built DC-X for c$50m, an unheard of price for high tech R&D) proposals.
X33 burnt through its build budget *and* its planned test budget (as NASA *very* generously allowed them to use that also) and *still* stayed in pieces on the ground. BTW an Aluminum tank which *matched* the shape and weight of the composite tank *was* built but a design "expert" stated that using would have destroyed the chain of component usage (demo multi-lobed composite H2 tank -> full size H2 tank), needed to build "investor confidence." (I'll bet LockMart management had a few ROFLMAO moments at that one).
As the design was "refined" its weight ballooned like a compulsive eater who had their stomach stapled to win Slimmer of the Year and having won has decided to let themselves go a bit.
Again in a *true* X programme the object is *data*. short cuts, single string control systems, looting old bits out the retired hardware warehouse are *all* acceptable *if* it keeps the schedule on target.
Lockmart choked off any *serious* competition for a generation, got some of their staff some on the job training and walked away from Uncle Same with better than $1.1 Bn having delivered virtually *nothing*.
And no one got arrested.
Just as long as they develop (in my lifetime) the ability to fly commercially to the other side of the world, in a timeframe that doesn't leave me a gibbering wreck. Let's say, 6 hours.
I'd pay the price of a 1st-class ticket to do that in a cattle-class seat. Currently, it's 36 hours door to door AKL-DUB. Grrr.
Oh, and some sharks with frikkin laser beams too.
"Just as long as they develop (in my lifetime) the ability to fly commercially to the other side of the world, in a timeframe that doesn't leave me a gibbering wreck. Let's say, 6 hours."
How does 45min sound?
It's called a ballistic transport and it was developed by a man called Philip Bono and described in a little rather colourful book called "Frontiers of Space" printed int he early 1970s.
Just in time for the last wave of oil price shocks and general eco-doom stories.
Despite decades of improvement in the theory and testing the idea still remains unproven but no one has actually proved it could not work..
Then look at Blue Origin's work.
Are you referring to Ithacus? A "plug-nozzle semi-single-stage-orbit launch vehicle [used] as a 1,200 soldier intercontinental troop transport"?? I really don't feel like being smeared across the rear bulkhead of somebody's rocket-powered meatbag-thrower.
6 hours is fine. A scramjet is perfectly acceptable, thanks.
Ithacus was one of several concepts discussed in the book. Bono had been working the idea for at least a decade and a lot of his thinking was reported int eh 1967/68 editions of Spaceflight (back when it was the only publication of the BIS).
His aim was to supersede the expected Super Sonic Transport (Concorde and its expected US competitor). In point of fact the vehicle would have been a lifting (semi-ballistic) flight with *much* lower acceleration/deceleration profiles (IE suitable for reasonably fit individuals who can survive a modern roller coaster without blacking out).
ICBM's pull stupid accelerations to keep the propellant mass small (because they normally fit into smallish containers) and because their engines have *no* throttling ability at all. Once you relax those conditions things get a lot more reasonable.
It would still be 45 mins to cross half the world. he also worked out the the energy consumption (often a complaint) is equal to the round trip fuel from roughly London to Sydney. A fact that is rarely appreciated. Fuel costs are virtually *nothing* The ET costed c$12m but the actual propellant about $1m (and you get big economies of scale)
Jenski sez on 11.24.10 @ 01:17gmt:
"Are you referring to Ithacus?"
Actually, I think you might mean "Icarus". But, yeah; I know which concept you're talking about... and come to think of it, you might be thinking of an entirely different Greek mythic being altogether:
http://www.astronautix.com/craft/pegvtovl.htm
"American manned spacecraft. Study 1966. Bono design for semi-single-stage-to-orbit ballistic VTOVL launch vehicle.
Drop tanks were shed on the way to orbit. Pegasus could deliver either a Saturn V-size payload to LEO or 172 passengers and their luggage the 12,000 km from Vandenberg to Singapore in 39 minutes.
The "Pegasus" was a Saturn V-class intercontinental rocket capable of transporting 170-260 passengers and 13-33.5t of cargo at 25,000km/h, or 90t to a 560km low Earth orbit. It would have been available in the 1980s and reduced the travel time from New York to Bombay from 22 hours to only 40 minutes..."
http://www.astronautix.com/graphics/p/pegasus2.jpg
...and I'll tell y'all what, I sure would've loved this bad boy on my trip to South Africa this past summer. Washington DC/Dulles to Johannesburg in _eighteen goddamn hours_ with a stop in Dakar to clean out the plane and for a mandatory crew change. Thank the FSM for the in-seat video entertainment system aboard the A340, otherwise I would've been raving'n'drooling by the time we touched down in Jo'burg.
Philip Bono proposed quite a number of variants over the years of his core design. Since my copy of Frontiers of Space went AWOL IIRC Ithacus was in there along with Hyperion (sled mounted, resembled the 1960's revival of the Sanger Silverbird) and Pegasus (which I think was more of the civilian concept).
Note that working for Douglas he had access to both the airliner issues (the operating cost equations) and the rocket side for the work on the Saturn 2nd stage (SIVb)
In airliner terms *bigger* is *always* better.
BTW The reason for these *monster* vehicle was 2 fold. Bigger is better but also mass estimation uncertainty.
With a bigger design you can in theory cope with more weight growth. Actually if you admit you don't want to go orbital (just very long range, very fast) you can relax the issues quite a lot. But now you have to bit a *very* fast moving (downward) and not too maneuverable (by aircraft terms) into an aircraft traffic pattern.
People *presume* he wanted a plug nozzle engine but actually that was *not* mandatory. The effects that plug nozzles rely on for altitude compensation *could* work with a bunch of normal engines just expanding around the periphery of a (very) big centre body.
Although that has never been tried in flight either. The closest seems to have been the 25Klb design made by rocketdyne under the leadership of Dr Hwang (That's the Hwang in Huzel & Hwang) but that got badly damaged in testing (Check AIAA for c1974 for the details).
Pictures of him show a dapper fellow with a fondness for white suits and a marked resemblance to Walt Disney.
So how much would it be worth for you to turn 18 Hrs into say 2 hrs?
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