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GlobalFlyer Aims To Go Voyager One Better
LucidBeast writes "We all remember Voyager, the first plane to fly around the world in 1986 on one tank of gas. Now Voyager pilot Steve Fossett plans to do it solo with a jet powered GlobalFlyer. See also New York Times article about it (registration required). The idea of the solo flight according to this story originated with the Voyager builder Dick Rutan." Update: 12/01 13:25 GMT by T : Note, the original submission reversed the roles of Rutan and Fossett; Fossett is the pilot, while Rutan (and his company, Scaled Composites) is the builder.
This little bugger
Steve Fosset is a millionaire balloonist who eventually made it around the globe after about 4 failed attempts. He had exactly nothing to do with the X-Prize winner AFAIK.
Burt Rutan is an aeronautical engineer and the the brains behind Scaled Composites who built the X-Prize winning SpaceShip One and the Voyager.
Dick Rutan is Burt Rutan's brother and he piloted Voyager around the globe non-stop in 1986.
From memory the pilot will be allowed to take naps on the flight. The aim with the jet was to allow it to fly high enough that it could reach the jet stream which would also take it over most of the turbulence. This will allow him to take naps of potentially up to an hour and if there is an issue that he needs to take care of, mission control will easily be able to wake him.
steve fossett is the round the world balloon guy.
burt rutan is the ss1 guy, and the voyager guy _and_ the guy building the Global Flyer. at the time of the voyager flight, the original concept was for a jet, or at least a turboprop, but at the time, those engine choices would not provide the kind of fuel economy necessary.
dick rutan and jeanna yeager flew the voyager.
the global flyer is being paid for by the Virgin CEO Richard Branson.
The difference between Theory and Practice is greater in Practice than in Theory.
The point of the GlobalFlyer is a SOLO non-stop round-the-world flight. So it seems the right time to mention that the Voyager non-stop round-the-world flight was piloted by two people: Dick Rutan and Jeanna Yeager.
If it isn't true, don't say it. If it isn't helpful, don't say it. If it's true and helpful, wait for the right time.
Well, it's not just that. What happens in an airplane in that as you decrease your speed, you are required to increase your angle of attack to provide sufficient lift to remain aloft. Now, as AoA increases, induced drag (the component of wing lift that is now pointing backwards) increases, thus reducing effciency. So, what you have are basically two drag components, parasitic drag, which increases by the exponential power of velocity, as given in your post, and induced drag, which increases inverse to velocity. At some point these drag-velocity curves intersect at a minimum drag speed, which is approximately the speed of best effciency, generally designed to be the cruise speed.
Another factor is thrown into the mix with non-constant (wrt velocity) thrust in jet engines. Jet engines are designed for best performance in an optimal speed range, and produce poor thrust from a standstill, but are incapable of functioning at a certain maximum speed limit (due to internal shock effects). For a generic jet engine, the efficiency curve peaks at about M=.8,.9 quickly plummets at M=1, and then climbs to it's best value at M=3, then decreases until M=5 or so, where operation becomes impossible. This is why most subsonic airliners fly in the region of M=.8 to M=.9.
At any rate, the point is that slower is definately not better when it comes to airplane effciency, particularly with regard to jet engines, which have optimal operating speeds.
BBC Link to an article that has a partial picture of the beast. Not slashdotted ... yet.
Less is more.
"If you go too slow, you'll drop out of the sky (duhhh...). If you go fast, you need less time but burn fuel like crazy. Also, for slow flying you might need more wing surface, read: increase the weight of the aircraft. So where's an optimum here? Anyone got some (informed) insights?"
It is more complex than that. Every airplane has an speed that is the best lift to drag ratio. It is usually very close to best climb speed. Below that speed you have to increase the angle of attack of the wing too much and you get a lot of drag. This also is very dependent on altitude as well as the air gets thinner the optimal speed increases. For some aircraft like the U2 family the stall speed, optimal speed, and max mach number can come very close to converging. And that can be bad.
Yes as you are right that as you increase the wing area you increase the weight but you also can increase the drag from the extra wetted area. Now if you increase the aspect ratio of the wing "make it longer and thinner" you will decrease the induced drag but then the weight can go up and that increases the induced drag. Everything on an airplane is a compromise. The trick is to find the best compromise for the job. Frankly Burt Rutan is very very very good at that.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.