JD didn’t check the fuel before he took off, and he couldn’t locate the switch that switched fuel tanks. The original design called for that switch to be located on the control panel. It was a kit plane, and many builders relocated that control to the firewall, which was behind the pilot. It had to do with shorter fuel lines and keeping the fuel lines behind the firewall.
I’m strongly pulled to respond, but have almost nothing to say because I can’t imagine what sort of confused whirlwind is going on in the OP’s head to prompt his questions.
Are you thinking of something like “Let’s take a 1920’s biplane and put it inside a modern shell and see how that flies?” Because *if *that is your thought, you’re essentially asking "What happens if we build a cargo airplane and then place a smaller airplane aboard *as cargo?" The answer to which is too obvious to explain.
If you mean “Can we take an existing airplane and powerplant and somehow enclose the airplane, but not the powerplant, is a better-shaped shell and thereby make it fly better?” Maybe, kinda, a little bit. For some spots in the operating envelope. But not across the board unless your original aircraft is a primitive piece of junk and your new shell is made of pure unobtanium with shiny new handwavium frictionless paint.
===========
- Airliner humor: Back in the 70s when the DC10 & L1011 came out and the standard mainline domestic aircraft were 727s, small 737s, and DC9s, the guys newly promoted to the DC10 & L1011 would joke to the guys on the smaller equipment: “Hey buddy, *I’m *flying the box *your *airplane came in. Neener neener.”
John Denver killed John Denver.
The plane he was in was modified. The original design had fuel lines running beneath the pilot’s seat to a valve to switch between main and auxiliary tanks on the cockpit front panel. The owner/builder of the plane Denver bought thought that was dangerous, so modified the design to place the valve behind the pilot’s shoulder (left shoulder, IIRC).
Denver was flying low, taking a fairly long-distance flight on his first flight of the plane he’d just bought. Flying low is dangerous; there’s no room for error. Flying a different type of plane than you’re used to carries special risks; you need to make sure you’ve put the plane through its paces and know how it behaves before adding risk such as taking a long flight or flying low for extended periods.
His main tank level ran low as he was flying very (very) low over the water just off the coast. Witnesses said his last maneuver was a sharp banking turn smack into the water, which is just what might happen if you were trying for the first time to operate a valve located just over your shoulder, naturally (but fatally) using your feet to help twist your upper torso to be in position to do it.
If he’d been at 10K feet, there’s a good chance he’d have been able to pull out of the spin. At 100 feet or so, no way.
If he’d practiced operating all controls on shorter flights where he might be less fatigued, he might have noticed the danger of twisting his upper body to operate the control (and not actually have had to operate it, having sufficient fuel). So he could have realized that it was an operation he should have practiced grounded.
Of course, if the original builder hadn’t tried to improve the safety of the original design, Denver would probably not have had that accident. No doubt there are a lot of sloppy pilots who lived long lives. Just not so many unlucky ones.
Moderator Note
Accusations of trolling are not permitted outside of the Pit. Do not do this again.
No warning issued.
I put the question in general terms because I wanted people who are particularly knowledgeable about this, such as yourself, Ravenman and possibly Stranger, to be able to respond in general terms too.
So, some background. Tell me at which point you grok the sense of my original question.
As you know, radars rely chiefly on specular reflections. Specular reflections are highly contingent on the geometry between the EM wave source, the angle of the reflecting surface and the receiver. Curves contain a high number of angles such that there is usually at least one angle in a curve which will give a specular reflection. Ergo: If you’re trying to reduce your probability of detection by radar, curves made out of reflecting materials like metal are bad. Hence, the Picasso-like look of the F-117.
The F-117 also shows that for an airplane, curves can be good. An airplane utilizes the fluid medium through which it’s moving. That medium is very flowy. If you want to make the most of it for high lift and low drag, you want to be flowy-looking, not Picasso-looking. Hence, the low payload and range of the F-117.
So, how do you solve that problem? You want your radar reflecting material to be shaped in a way that make it bad for flying. But you want your airframe to be good for flying.
Hypothesis: Make an inner airframe out of radar-reflecting material which is optimized for reflecting radar waves away from whence they came. Then, around that, put an outer airframe out of radar-transparent material which is optimized for high lift and low drag.
Now, that hypothesis may be inaccurate but I like to think it’s less a confused whirlwind and more a cogent whiff.
The F-117 was known as the ‘Hopeless Diamond’ shape. I like that better than Picasso. 
Which is pretty much what we have with the Northrop-Grumman B-2. The substructure has angular radar-trapping geometry, and the parts you see are radar-absorbant materials (RAM).
That’s what I was guessing, yes.
The datum about the B-2 substructure having angular geometry, is that open-source intelligence? Where did you see it confirmed that it did?
I’ll have to find a citation.
Now that you explain it your idea makes complete sense. Very creative. Not so much a whiff on your part but rather a fastball that blasted past all us conventional batters.
IANA an expert in this area, but I suspect it’s an idea whose time came and went about along with the F117.
The B-2 is much more naturally aerodynamic than the F117. The latest stealthy F35, X-47B UCAV, etc., are even more so.
IOW, since the F117 design era we have learned how to be both aerodynamic and stealthy with the same shape.
A different objection that I don’t know enough to quantify is that carbon fiber composite materials are electrically conductive. Which I suspect means that they’re radar-reflective, not radar-transparent. So it wouldn’t be a good choice for a false outer skin in a non-stealthy shape.
Traditional fiberglass is radar-transparent. Whether you could build and structurally support enough large areas of it strong enough to hold up to modern jet speeds is a good question. Overall I’d suggest you’d have much better luck doing this to a bomber aircraft with low G requirements. For a fighter, the higher G loading would require a lot more structural strength in the shell and its supports.
ETA: Ref Johnny L.A. … If indeed the B-2 is angularly stealth shaped on a micro-scale (say 1" sawteeth) with a RAM coating then you get the best of both worlds.
OK, I found this:
And:
Now, the Wikipedia article mentions the Blackbird series and not the B-2; but since it says the structures were ‘first used’ in those aircraft I think it’s a safe assumption that it’s also used in the B-2, as indicated by the google books result.
This actually isn’t true for most aluminum skinned aircraft. The skin is acting both as the aerodynamic fairing and as the structure. In wings, the skin is usually required to resist the torsion loads. This is referred to as “semi-monocoque” constructions.
More than speculation, the biggest issue with radar evasion is vertical surfaces. That is why the B-2 is a flying wing with a blob in the middle: the radar beam that does bounce off the plane goes up or down, not so much back toward the antenna.
Planes like a rudder, the Wrights found this out, because they counter a thing called adverse yaw: when you bank into a turn, the upper wing which needs to move faster experiences more drag (in whole or part because it is moving faster), so it wants to lag rather than advance, as you want it to. Most likely, the B-2 counteracts adverse yaw simply by directing engine force (balance), bypassing the need for a big vertical surface back there. Though, of course, if you are banking, you may be exposing your underbelly to reflecting radar more.
One must consider that the need for metal in an airplane’s structure is increasingly a design choice rather than a necessity. Certain things just gotta be metal: engines, landing gear, etc. But using carbon fiber both as structure and skin is not revolutionary. The guys at Scaled Composites, now owned by Northrup Grumman, have been doing this for ages. And if you can use composites in such a way, I don’t see why building two structures is necessary. You just build an airplane, not an airplane in a separate case.
The second source mention of re-entrant triangles would suggest that they built the radar equivalent of an outward-facing anechoic chamber. I don’t know much about aeronautics but it sounds like that would be a pretty unaerodynamic surface without the smooth radar transparent/absorbing outer surface.
True, large parts of the plane can simply be built out of radar transparent material with no need for a radar deflecting substructure. The parts that have to be built out of metal can be significant, though. The ordnance bay alone will be filled with lots of metal stuff, at least for part of the journey.
Also, since one cannot have a radar-transparent radar array, I wonder if the radar is housed behind a radar-reflective surface that’s moveable in some way.
And as LSLGuy mentioned, non-metals tend to have a tough time with the high G loads required of fighters.
Might not be that big a deal. After all, one pilot managed to land an F-15 with one wing ripped off. (And apparently the plane was repaired and put back into service.)
But with a fighter, you’re also not looking to have high lift as you propose this fairing to provide. You’re also not going to look to make it any larger than required, which runs counter to the idea of a fairing because of the associated increase in drag.
Wings are un-aerodynamic without a smooth outer surface. I don’t know what the internal structure of a B-2 looks like, but here is a cutaway view of an SR-71. You can see the triangular construction of the edges of the wing. To my eyes, it doesn’t look structurally different from the leading edge structure of any number of non-stealth aircraft – except that the ‘leading edge ribs’ are arranged in triangles. That is, the structure has to be there anyway; they just optimised it to trap radar.
IIRC – and I may not be – the F-117 didn’t have radar.
The B-2 uses spoilerons to deal with adverse yaw. Each aileron is composed of an upper and lower surface which can be moved together as an aileron or split apart to function as a spoiler. With a left roll input, the right aileron moves down and the left aileron moves up and also partially splits to maintain coordinated flight.
My understanding is that the mission profiles flown play a large part in preventing the second problem you mention.
Ah, so the OP really wanted to know if one can cover an existing non-stealthy aircraft with non-metallic materials and end up with a stealthy aircraft that would work as well (or better?) than the original construction? Okay.
No, your reading comprehension is lacking.