Jun 112010
Another minimally-described 1977 concept, this time a fighter meant to cruise at faster than Mach 5. Apart from having some impressively large engines, not much about this design screams “hypersonic,” but rather “Mach 2 or so.”
3 Responses to “General Dynamics Hypersonic Cruise Vehicle”
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Reminds me of a couple Boeing designs from the 80s
You can see the engines as being some sort of turbo-ramjets or injector ramjets, but their position that close under the wing is going to create pure hell in regards to airflow once multi-Mach shockwaves are taken into account.
If the wing leading edge was perpendicular to the engine intake inlet in front of them it might work, but the combo of highly-swept leading edge and circular intake design that far aft of the leading edge is a complete mess.
Don’t even get me started on how hot those cockpit window panels are going to get at Mach 5 with a design like that.
That explains why the engines are so far aft; that’s to counteract the weight of all the quartz glass in the canopy. 🙂
That was supposed to be _Ejector Ramjets_ BTW.
The whole design seems to owe a lot to the souped-up canard-equipped B-58 designs that were supposed to use Mach-3 style turbo-ramjets like those employed on the Lockheed A-12.
It looks like a sub-scale version of one of those designs, but seems to suffer from the same basic problem that the whole B-58 series did – insufficient vertical tail area to keep it stable at supersonic speed in the yaw axis.
Take a look at the vertical fin area on a F-102 or F-106 and compare it to that of a B-58 sometime.
Failure of either of the outboard engines on the B-58 caused it to immediately crab into the air at such a severe angle that airflow to the inboard engine on the same side was disturbed enough that it flamed out, and at that point the aircraft went into a fatal flat spin that overstressed the airframe to the point where it fell apart within a few seconds after the outboard engine failed.
One has to remember that the B-58 program went so far back that the roll coupling problem that the X-3 showed was the cause of so many F-100 crashes, due to too small vertical fin area, wasn’t known when the basic design was being come up with.
As to why General Dynamics hadn’t figured that out by the time they came up with this design is a good question.
A supersonic unstart of either of the Blackbird’s inlets was severe enough to shake the crew up but good, but at least the aircraft kept going front-end-first till both engines could get up to thrust again, due to the large area of the twin vertical fins.