h a l f b a k e r yAlas, poor spelling!
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Ideally, a Jet engine is a hollow tube with a flame (expanding gasses) in the middle. The flow of a fluid (air in most cases) then creates a directional thrust. To further the effect, rotating fans create this airflow in the direction that is desired.
My theory is for a spherical combustion chamber
with eight holes, cooresponding with the X, Y, and Z axises. Over these holes, some type of heat-resistant "iris" shutter(like in a camera) is fitted. The fuel is injected from the diagonal corners of the sphere (where there is no hole), and depending on the desired direction, shutters are opened. To begin with, the engine would operate primarily like a rocket, using the expanding gas as the sole means of propulsion, but as the speed increases, the shutter of the opposite direction could also be opened, and then engine would operate like a RAM-jet(jet engine that uses no rotating fans)
Obviously, the speed could be controlled through 1: fuel flow, and 2: shutter width, and direction could be changed by opening more than one shutter. One proposed vehicle would be a cabin with four of these engines on pilons jutting out from the upper corners of the roof. They would have to be at diagonal (45 degrees) with the pylons, to provide them with free range of exhaust, without danger of burning off their supports and killing pilots and passengers. This vehicle would then be able to perform VTOLs and many acrobatic maneuvers that are only limited by the strength of the airframe, the pilots stomach, and the type of fuel used.
The Delta Clipper
http://www.hq.nasa....tory/x-33/dc-xa.htm
NASA's VTOL rocket experiment. [8th of 7, Oct 04 2004, last modified Oct 06 2004]
Batter up!
http://www.houseofh...phantasmreviews.htm
[bungston, Oct 04 2004, last modified Oct 06 2004]
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In what way is this a new suggestion? |
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I R no physicist, but what about lift? |
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Overlooking any issues with designing an efficient, thrust-producing spherical combustion chamber...(assuming you had this), directional control would be poorly served by 6 discrete exhaust vectors (polar coordinates of x,y,z, relative to airframe orientation. Not sure where you are suggesting the 7th & 8th 'holes' would be). IR no engineer either, but I think a design with a single exhaust and rotational/pivoting control over direction would work better, especially for VTOL. (Look at the difficulties the Osprey design has had).
That said, I have also seen new aircraft designs using baffles to redirect jet exhaust in two vectors (down/back), though these craft rely on conventional airfoil design for control. |
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I also was confuseled by the other two holes, but [jong-scx] mentions 'diagonal corners of the sphere' which I assumed to indicate the diagonals of a *cube*. I decided not to bother with confirmation as it stopped making sense long before then. |
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The biggest problem I can forsee would be rapid erosion of the iris structures, even if they were make of highly refractory material. Even a partial failure of one iris would be immediately catastrophic. |
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Ramjets rely on developing a standing shockwave in a long, carefully profiled tube. I don't think this goes well with the concept of a spherical combustion chamber. |
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The idea addresses lift and lateral motion, but not roll and yaw (rotational forces) issues due to potentian asymmetric thrust and turbulence in the hover. |
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OK, IR no physicist either (I'm not even out of high school yet), but what about a space application , where lift would not be an issue. |
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RE angel, the "diagonal corners of the sphere" was in relation to the fact that I did find a lot of it absurd after the second paragraph! and The miscount of the axises produced the 8-shutter thing that many have raged about |
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And Many Have RaGeD. The new hit album. |
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VTOLs like the Flying Bedstead, of which this is a derivation are more practical today with modern control system technology. |
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The only issue is one of efficiency. Today, AFAIK, there is no production VTOL vehicle that does not employ a lifting surface to some degree or other device to counteract the effect of gravity. |
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Helos (VTOL) have rotating wings,
Harriers (VTOL/VSTOL) have fixed wings
Rockets (no VTOL examples) rely on momentum |
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Your device, like the flying bedstead or rocket pack, will likely have a very short range and flight duration |
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Stick with it. Keep the ideas flowing. HB can quite be hostile to the sane/ practical. |
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// Rockets (no VTOL examples) // |
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There was that McDonnel-Douglas VTOL prototype that they built for NASA as a potential shuttle replacement, but it crashed and burned. I'll try to find a link. |
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//Rockets (no VTOL examples)//
Apollo LM? |
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The Apollo LM is a bit of a cheat (hybrid), because it was actually two components; one of which was vertical landing only, the other vertical takeoff only, the one being the carrier for the other. But that's at least two instances of a VTOL rocket system. |
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//McDonnel-Douglas VTOL//
//Apollo LM// |
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To clarify I had in mind aircraft intended to operate in the Earth's atmosphere. The LEM can only work in the airless, low gravity environment of the moon. Also, the LEM is not in production (although it has been produced). BTW, AFAIK the flying bedsted was a proof of concept project in the Apollo program. |
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The MD-VTOL is a lovely concept, right out the pages of a Flemming or Herge novel. It may well prove commercially viable, but is not as yet in production. When it does, it isn't intended to achieve the radical manouvering that [jong-scx] intends. |
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All said, I stand partially corrected. |
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Needs Korean language support, in case you don't have it: |
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Mian hamnida. Komapsumnida. |
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Why not make an icosahedral rocket with 20 valves, with the output of each valve controlled by a computer. Heck, make a bajillion little valves, since a computer is keeping track of them. The failure of one little valve would no longer be catastrophic, just wasteful, since the valve immediately opposite it on the rocket would need to also open completely in compensation. As regards lift, whichever valves are on the bottom will of course be blasting away the most - this in an environment with gravity. If the robopilot needs to rapidly dive, these are shut off and the top valves are opened, propelling the craft rapidly downwards. |
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I like it. It reminds me of that nasty little ball the jedis used for light saber practice. Which in turn reminds me of that flying blade-egg from the movie Phantasm. Maybe the spherical rocket, the jedi ball and the blade egg could team up and fight evildoers? |
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Kind of reminds me of "The First Men in the Moon" by H.G Wells. |
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[bungston], what you end up with is a sphere which is just a combustion chamber with a large number of small apertures distributed over its surface. There is no provision for fuel storage, distribution, or the control system. |
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SIx nozzles for 3D manouvering in vacuo makes some sense, but anything beyond that starts to produce more problems than it solves. |
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I'm sorry but I think that rockets should be rocket-shaped. Otherwise they're just not rockets. That's all there is to it. |
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I can see the advantage of having a landing ball. Very much like the use of airbags to land the pathfinder mars probe. no need for landing gear & the addition of retro rockets to soften the fall. |
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//Ideally, a Jet engine is a hollow tube with a flame (expanding gasses) in the middle.// |
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Jet engines happen to work in a lot more complicated manner than this! Since your whole idea is based on this "ideal" oversimplification of a jet engine (without all of the internal workings), I'm going to have to throw you a bone here! [-] |
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yes rocket canna suddenly be ramjet/scramjet just cos you make it go fast. no bone. |
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