I wrote the initial version of that Wikipedia article. Those big piston engined planes fascinate me.
The installation in the B-36 was sub-optimal, though; the reversed, pusher configuration wasn't what the engine was designed for. The carburetors were meant to be after the engine and warmed by the airflow over the cylinders. Pusher configuration meant the carbs were first and got cold, sometimes damp air. Carburetor intake ice buildup meant the engine's mixture ran richer and richer until, fairly frequently, the engine caught fire. It wasn't uncommon to lose an engine or two during a long flight.
Especially scary in an aircraft built largely of magnesium. I'm sure you all remember high school science class, and how magnesium burns.
A brighter future for a darker age....Why would you build a plane out of magnesium? Surely the galvanic corrosion resistance isn't worth it on something that regularly gets shot with incendiary rounds?
Fight smart, not fair.I've never heard why it used magnesium so much. I suspect structural properties, rather than anything else.
I suspect incendiary rounds wouldn't light it. Only a sustained fire would.
edited 24th Apr '10 2:48:51 AM by Morven
A brighter future for a darker age.It's a fairly light metal, but I wouldn't expect it to be strong enough to be useful in an airframe, but I know exactly nothing about engineering of things more complex than a tent, so take that with a shaker of salt.
I have an anouncement in regards to that animation: Wankel. That is all. (If you get the reference, 200 points).
Charlie Tunoku is a lover and a fighter.According to the other wiki, it has a similar level of strength to volume as aluminum. Although the whole "easily burns" thing is what throws me. Seriously, it's not that cheap, why would you build anything out of it. I could see coating, but why build?
Fight smart, not fair.Hungry Joe, I got the reference. The Wankel rotary engine, by any chance?
Locking you up on radar since '09I guess magnesium was used in airframe construction since it is pretty light and strong, like aluminium. The main problem (if I remember that correctly) was that it is rather hard to weld.
The Wankel engine, well, communism worked too in theory. It is lighter and simpler than conventional piston engines, but it has a higher fuel consumption and you need a lot more sealing. Depends on what it's used for, really.
A different shape every step I take A different mind every step of the lineYes, it's hard to weld, but possible; Northrop developed a welding technique for the XP-58 project. I suspect that what was used in the B-36 and other airframes was a magnesium alloy, perhaps magnesium/aluminum, which appears from what I've looked up to have better properties than either metal on its own.
A brighter future for a darker age.Now magnesium alloys, I've heard good stuff about.
edited 25th Apr '10 12:11:17 AM by Deboss
Fight smart, not fair.Magnesium alloys are pretty good for sure, certain aliminium alloys contain magnesium to make them stronger and magnesium absorbs vibration pretty well. But I guess nowadays composite materials like fiberglass and carbon fiber are taking over as the light-weight high-technology materials in aviation.
A different shape every step I take A different mind every step of the lineI believe it's because carbon fiber and fiber glass are easier to mold than metals which require "heat 'n beat".
Fight smart, not fair.I guess. Quite a lot of new aircraft are manufactured with composites and carbon fibre.
Locking you up on radar since '09The problem with such materials is that the only way of manufacturing parts from them is to make the shape out of something else and then laminate the part layer by layer.
On a rather different note, does anyone think it is possible to perform any sort of aerobatics with a large aircraft not designed for it? It sure is possible in Flight Simultor (I've tried barrel roll and loop in a 747), but of course that is highly unreliable. On the other hand, it's surprising what can be done with some aircraft. Any opinions?
A different shape every step I take A different mind every step of the lineAt best, you'd overstress the airframe, meaning you'd have to be really gentle with it once you've done one (yes, one) manoeuver. At worst, it'll experience structural failure and you'll lose control.
Locking you up on radar since '09Probably. Stressed airframes are dangerous things, as was learned from the first-generation BAe Comet.
edited 26th Apr '10 2:38:07 AM by catfish42
A different shape every step I take A different mind every step of the lineSo the moral is:
There's a reason why certain aircraft types aren't certified for aerobatics, and why all aircraft have VNE (the Never Exceed speed).
Locking you up on radar since '09FWIW, some years back on History or Discovery Channel, they ran a mini interview with a guy whose dad had been a test pilot with Boeing. He was talking about (and showed home movies of) his dad doing a barrel roll during the first 707's test flight.
I remember that anecdote. Apparently the chairman of Boeing was seriously shocked by it.
Locking you up on radar since '09Nobody's ever rolled a B-52; I know that was the ambition of the idiot hotshot who caused the 1994 Fairchild AFB crash. It's strictly forbidden by the manual.
I recommend watching the video of that crash to get properly worked up about how fucking stupid that pilot was.
edited 26th Apr '10 12:57:09 AM by Morven
A brighter future for a darker age.Well, the B-52 has very long and rather flexible wings, so any sort of extreme flying is very risky. The Avro Vulcan on the other hand (smaller and delta-winged), is far more capable in that respect, the Vulcan prototype has been barrel-rolled.
British planes are just cooler.
A different shape every step I take A different mind every step of the lineMost wings are quite flexible. Provided you don't mind them being warped.
Fight smart, not fair.The B-52 is especially dangerous to do such stunts in because it lacks ailerons; roll control is through spoilers, which work by killing the lift over a section of the wing by disrupting the flow over the top surface.
A brighter future for a darker age.Sure, aircraft wings have to be flexible, otherwise they would break easily under the stress induced by any sort of maneuvering. But as the wings of a B-52 are very long and thin and also carry the eight engines, they bend even easier. And of course, don't over-bank an aircraft, it will "slide" sideways and lose a lot of height.
A different shape every step I take A different mind every step of the line^That's pretty much a side-slip, if I remember correctly.
Locking you up on radar since '09
I never knew that! Thanks for being a wealth of information!
Locking you up on radar since '09