h a l f b a k e r yQuis custodiet the custard?
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First, see link about the V22 Osprey. This aircraft, when flying, looks ALMOST like an ordinary propeller-driven plane, except the propellers are HUGE. And for each engine assembly, including the huge propeller, the whole thing tilts, so that the prop can force air downward instead of rearward. This
allows the plane to land and take off vertically.
The V22 has also had a lot of development problems; quite a few deadly crashes have occurred. But the military has a huge huge need for a plane with capabilities like the Osprey, and so now I can present this Idea.
When building this plane, we start with the fuselage oriented vertically, like a rocket. Passenger seats are laid-back, too, just like in a rocket. Kind-of stubby, though. We attach one LARGE set of mostly-ordinary wings, also oriented vertically, unlike like Osprey wings in the take-off position. We will almost certainly need 4 engines on these wings, with large prop blades. Look at the second link, regarding the "blended wing body aircraft"; its a kind of flying wing that has significantly thick middle section, much like an ordinary aircraft fuselage. The stubby length is balanced by width; part of the interior of the wing-space is useful for transport; the total transport volume is roughly the same as an ordinary large aircraft.
Now for the +. This is a smaller wing also attached to the fuselage, oriented at right angles to the first. From above, the overall shape of the plane would look something like a plus-symbol, except these secondary wings are smaller and only have two engines on them (also with large prop blades). This smaller wing is specifically called the "+Wing" in the text that follows. Note that the overall + shape has great stability; the plane won't fall over when built/parked in that vertical orientation.
After being built, all six engines are revved up, and the whole thing takes off just like a helicopter. Once a reasonable altitude is achieved, the purpose of the +Wing is revealed. One engine is revved up even higher, and the other engine is slowed down and perhaps even turned off. This causes the entire aircraft to start tilting. The four big props on the main wing, of course, are tilted right along with it, and they start giving plane motion in a "forward" direction. This motion of course now lets the huge wing start to grip air and act as an ordinary aircraft lifing surface.
With the wing now starting to provide some lift, the whole aircraft continues to tip over until full ordinary horizontal flight is achieved. Now the two motors on the +Wing can be revved back to normal speed, helping the plane get to its destination. The fixed-in-place passenger seats have of course also been tilted with the whole aircraft, to the standard/ordinary position.
At the destination the OTHER +Wing motor is revved up, (not the one that originally caused the plane to start tilting after take-off), which causes the plane to start re-orienting back to the vertical position, in preparation for landing.
(?) V22 Osprey
http://www.boeing.c...itary/v22/index.htm
As mentioned in the main text [Vernon, Oct 06 2006]
Blended Wing Body
http://oea.larc.nasa.gov/PAIS/BWB.html
As mentioned in the main text [Vernon, Oct 06 2006]
Like this?
http://aerofiles.com/convair-xfy1.jpg
from 1954 - Convair XFY-1. Just add small props on the wing tips. [ConsulFlaminicus, Oct 06 2006]
Or this?
http://en.wikipedia.org/wiki/Lockheed_XFV
The Lockheed XFV-1 from 1955 [ConsulFlaminicus, Oct 06 2006]
Downloadable model
http://www.fiddlers...ockheed-XFV/xfv.php
You can even use these as a prototype tool [Vernon]! [ConsulFlaminicus, Oct 06 2006]
[link]
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Not recommended for transporting jeeps, I guess. |
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I propose passenger seats be replaced by hammocks, which are cheap and will reorient themselves automatically. And much more relaxing. |
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So the whole plane tilts from vertical orientation to a horizontal one? You could do something similar by strenghtening and attaching wheels to the rear of a traditional plane, and have the pilot perform a near-stalling manouvre that leaves his plane's nose pointing in the air. |
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I'm not sure how such a pilot might manouvre his craft (other than simple up/down controlled by varying the throttle control) while it's in vertical mode - and the same question applies to the +Wing. |
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[moomintroll], you put the jeeps inside the fuselage, before take-off. You park them at an angle equivalent to 45 degrees uphill. In flight, the plane changes its orientation by 90 degrees; the jeeps are now titled to an angle equivalent to 45 degrees downhill. Simple. |
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[zen tom], All wings have flaps on them to influence air-flow. This combined with the motors on the +Wing should allow reasonable orientation control. The three types of reorientation are called "pitch" (nose up-down), "roll' (one wing up while other goes down) and "yaw" (seen from above, plane turns left or right). In this plane, during ordinary flight, the +Wing is in charge of pitch-control; the wing-flaps (aerilons) can control roll, and the four main engines can be revved at different speeds for yaw control (usually handled by a rudder or "vertical stabilizer", and note I haven't precluded adding that). In vertical flight mode, the roll-controlling aerilongs are sufficient to rotate the wings slowly around the central axis through the length of the fuselage, to whatever degree needed. |
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I'm not sure that this would have less development problems than the Osprey (I'm fairly sure it would have more), but it's a feasible proposition and would look awesome taking off. More out of the box thinking from Big Vern. [+] |
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[wagster], I think most of the Osprey's problems are related to the fact that the wing doesn't tilt along with the engines and rotors. That downblast of airflow hitting the horizontally oriented wing can't be good! In this design you not only have the airflow always going over the wing "properly", you also don't have the moving parts associated with tiling the engine nacelles (OR with wings tilting while the fuselage stays horizontal). |
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I'm not sure you want the air going over the wing "properly". Traditional lift, rotated 90 degrees is going to result in horizontal motion - which is fine if you want to go that way, I suppose. |
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[zen tom] the aerilons can control that adequately. |
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[ConsulFlamincus], those linked 1950s planes are single-pilot. I'm describing a fairly large aircraft here, rather taller and with a LOT bigger wingspan. |
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The transitions sound very problematic. |
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When you start tilting you are going to be well below stall speed for quite some time. Especially with the wings tilted "up" at a rather extreme angle, so are not going to provide much lift (or control) until the craft is mostly horizontal and at speed. At the same time the rotors are tilting away from vertical and giving less and less lift and control. |
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I suspect that this will be even more difficult on landing. When you start tilting up your wings are going to reach a stall point long before your rotors can provide enough lift to make up for it. This is going to give a very exciting ride. |
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Perhaps extra large propellors with controllable pitch like those of a helicopter would help... some... You could then move it somewhat like a regular helicopter for a bit to gain some foreward momentum before that rough transition. |
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[river] That is going to help up until a certain point. At some point it will drop off. I suspect that point is less than 45 degrees from vertical. I know that conventional fixed wings stall at well below 45 degrees from horizontal. This means that for some portion of the rotation there will be little or no lift (a condition also known as falling). |
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The V-22 avoids this by tilting the entire wing, this way the prop wash flows over the wing and provides some lift during the transition. |
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Funnily enough CF, that was what I had in mind too. Those aircraft managed to get from vertical to horizontal without extra engines or tilting mechanisms. I think vectoring the thrust, using flight surfaces, might have been the method they used. |
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Folks, the changeover isn't that tough a problem. From vertical to horizontal, you trade altitude for speed, even if it is a falling speed, and use that speed to to reorient the vehical (to horizontal), with the props helping a lot. From horizontal to vertical, you use your forward velocity (400kph?) to start climbing toward the vertical; by the time you are vertical, you have lost all that airspeed, but now the props are holding up the weight of the vehical. |
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The entire reason for developing the Osprey was to eliminate the many issues involved with tailsitting air craft designs. They are very hard to load, cannont use space as effciently, cannot be easily maintained and generally are very impractical. Your idea here is really just a big version of the planes shown in the links. |
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The question I have relates to the very gist of what makes this idea different. Why six engines? Given that the move from vertical to horizontal can be achieved with just one engine and some fairly ordinary control surfaces / flying techniques, why are six engines required? I mean, it would look impressive, sure enough, but what's the scientific justification? |
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[david scothern], that's a reasonable question. The answer has to do with the size of the prop blades, vs the load, AND vs the speed of sound. There is a two-"prop" helicopter (the Huey?) that has fairly standard-size blades, and maybe only one engine powering them, and it lifts a reasonable load for a big chopper -- but remember that choppers don't fly so fast in the forward direction. Notice I mentioned "400kph" in the main text? To do that the prop blades must spin faster, and large blades will have tip-speeds that will exceed the speed of sound, with a lot of accompanying problems. So, to go fast you need smaller props, and to lift a big load you need more of those props. And since VTOL speeds are pretty slow, you can't expect good performance from aerilons at those speeds. |
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Another thing is the mechanical complexity of the helicopter rotor-joints. To allow a chopper forward motion, the blade pitch is constantly changed even as it makes one single circle. Multiple engines with fixed blade-pitch (or slightly-adjustable pitch, nothing as complex as helicoptor rotors) just seems simpler, than trying, while oriented vertically, to go sideways fast enough for the aerilons to catch enough breeze to fully reorient the vehical to the horizontal flight mode. But an unbalanced prop-induced breeze, as described in the main text, ought to work efficiently. |
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I disagree with [jhomrighaus] about loading this vehical. The Blended Wing Body design is very spacious. Storing stuff on multiple levels then becomes more of a design problem (see what I wrote about Jeeps in an earlier annotation). Another possibility, if interior floors are deliberatly angled for such a purpose, then when on the ground perhaps some way of tilting the entire craft (to 45 degrees) could be arranged, for easier loading. |
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