Will someone please take this lot aside and point out to them that jet aircraft are the shape they are because of something called aerodynamics and anything cobbled together from aesthetics is going to auger straight into the ground faster than you can say Icarus?
Thank you.
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| Um, where are the pedals? |
13 comments:
Unfortunately, the rise of fly-by-wire (and subsequently fly-by-light) controls, allied to the ability of computers to cope with the demands of flying a staticaly unstable airframe, means that this probably could be made to fly. Indeed, it would probably be all the more manueverable as a result.
As one of the guys who worked on the F-117's avionics is supposed to have said - "with this computer and enough thrust, we could make the Statue of Liberty do barrel rolls"
Mind you, I wouldn't want to risk a birdstrike on that canopy
The only vertical surfaces are positioned ahead of the center of gravity, and that would probably make the whole thing tumble like a very heavy piece of paper all the way to the ground. Just the most obvious complaint. Couldn't resist writing it.
Way I heard it (when I were a lad, back in the days of Yaroslav the Corpulent (or was it Ivan the Bucktoothed?)), it was, "with enough engine, you can make a barn door fly". Maybe put a huge chunk of lead in the nose, to bring the CG forward?
best analogy for relaxed stability aircraft I heard - Imagine sitting on the bonnet (hood) of a car, holding the handlebars of a bicycle which is in front of you (facing in the opposite direction to the car). Now, as the car drives forwards, you must try to keep the bicycle upright by steering the handlebars.
Humans might be able to manage up to about 10mph, but a computer can cope with a lot higher speeds.
The lack of rudder pedals indicates that the DFBW system would take all control inputs through the yoke. Myself, I'd want a sidestick on the armrest to deal with G forces at high AoA.
Yes, it would definitely fly. And assuming a high composite content in the structure and skinning, it would probably have a fairly low RCS as well.
However, with all the drag-and-vortex-inducing "zigs" and "zags" in its wing, I'd expect it to handle about like an F-117. Which the pilots nicknamed the "Wobblin' Goblin", and not out of affection for its handling characteristics, either.
Which means you'd want a highly-trained professional behind the controls- not a rich-boy Top Gun wannabee. The latter would auger this sucker for sure.
Also, governments aren't going to tolerate private pilots screaming around in Mach 3+ birds in commercial lanes or oil-burner routes. To say nothing of their reaction to the commercial availability of what is basically a stealth strike aircraft.
It might not be pretty, but it could be a "poor man's Nighthawk" in the bomb-dropping department. Governments hate that- after all, the bombs might be aimed at them.
cheers
eon
Add enough lead in the nose to stop the tumbling, and the moment arm between the CG and the wing's center of lift will be so large you'll need abnormally high speed to remain airborne, and the plane will be very sluggish (and stable) in pitch, while unstable in every other axis.
Flying it would certainly be a very interesting experience, maybe even fun, but not in the way the designers had intended. And why did they have to make it so ugly ? :)
Daniel,
In Britain it was making a tea tray fly.
The fly by wire instability reminds me of the story of the Fokker D7 during WWI, which was so unstable that if you touched the joystick wrong it would prang. When it came time to show it to the Germans, the Fokker representatives took the German pilots aside and told them that the D7 was "ultra-manoueverable" and required delicate handling, thus turning a fatal design flaw into a selling point.
Lemons and lemonade, I suppose.
Maybe with sufficiently powerful avionics and fast control surfaces the thing would fly. But it still looks like a ten-year-old's interpretation of a Batplane (with a sparrow's-head cockpit glued on as a joke). My smoothly flowing designs, by contrast, look like they were rendered by at least an eleven-year-old.
of course, the proposed performance is absolutely hilarious - top speed of mach 9.8? The F-111 was limited to no more than 10 minutes of top speed at low level, as frictional heating meant that the canopy started melting if it went any longer.
Presumably, the canopy on this design must be made from synthetic diamond (or unobtainium...)
David;
The Sopwith Camel had similar problems. It was highly maneuverable, simply because it was, in modern terms, a "relaxed static stability" design- another way of putting that is "fundamentally unstable". It literally had to be "flown" every second from "contact" to shutdown, even in the takeoff and landing runs. It wasn't exactly a docile "taxier", either.
It also had some quirks that could be deadly if you weren't familiar with them. Among other things, fast, diving turns to the left were prohibited, as the combination of the movement plus engine torque (the entire radial engine rotated around the crankshaft to enhance air cooling) could turn the maneuver into an unrecoverable flat spin.
The Camel had the best kill ratio vs. the German fighters of any Allied fighter in the war, due to its high maneuverability in a furball. It also chalked up the highest casualty rate for trainee pilots in practice, plus takeoff and landing, due to its unforgiving handling demands.
An old aeronautical engineer's saying goes, "Safe, Agile, Fast; Choose Any Two." The Camel was a case in point.
cheers
eon
Daniel;
I can (sort of) buy a never-exceed speed of M=9+ with the ramjet propulsion system mentioned in the article. As for the canopy, I'd expect something more like an X-15 or SR-71 solid canopy with small windscreens, probably quartz, for a speed run like that.
Vision would not be good.
(I once sat in the pilot's seat of a Blackbird, at the National Museum of the U.S. Air Force, in Fairborn, OH, and concluded that anyone flying it was on IFR from the second he let the brakes off, even on the taxiway to the active.)
The composite materials could probably handle the thermal shock and aeroelastic stress of high-Mach flight, at ~high~ altitude. With a hybrid turbo-ramjet propulsion system, I'd figure that pushing it past M=2.5 or so below 40,000 ft (12,000 m) ASL would be possible, but asking for trouble. In the sense of a rather spectacular "in-flight catastrophic self-disassembly", as they used to say at Farnborough.
cheers
eon
One big advantage of staticaly unstable airframes is the ability to make them do things conventional aircraft would find impossible.
In the late 80's and early 90's, all the talk in fighter jet design was about "Control Configured Vehicles" - fighter jets designed to be dramatically unstable, rather than just "relaxed stability". The main attraction was the ability to decouple flight path from attitude - CCV demonstrator aircraft (some of which looked pretty damned strange - there was an F-104 with a second tailplane just behind the cockpit) demonstrated tricks like flat turns, ascending and descending while remaining at the same angle to the horizontal or, conversly, changing the angle of attack while maintaining a level flight path, and finally sideslipping horizontally and its corrolory, yawing the aircraft while maintaining a straight flightpath.
Unfortunately, it was almost impossible to design a control interface for such an aircraft that didn't require all the pilots concentration to use.
Daniel;
Another problem with CCV-type fighter aircraft is that in pulling such out-of-envelope maneuvers, they can easily generate pilot-killing G loads without half trying.
For this reason, I suspect that the future of CCV- type combat aircraft will be with UCAVs- Unmanned Combat Air Vehicles. Microprocessors generally don't care how many Gs you subject them to, or whether they are positive, negative, transverse, or two or more of the above at once.
While the pilot sits safely on the ground and only has to worry about where his next target has got to.
cheers
eon
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