Ejecting wings?

[angeldust]

Hello everybody!

Did you ever have the problem that your awesome (space-)plane technically flies like a flying saucer, but will not take off the runway until the end, where it falls off and the angle of attack becomes big enough? Well, I had it!

So I thought about this:

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What do you think? Is that a good idea? The swept wings are ejected as soon as the plane is flying. They can not stay on, because the plane tips (too much lift on the nose).

After a while I ejected the outer part of the main wing. Is that a good thing to do?

I'm interested in your oppinions =)

Edited September 22, 2014 by angeldust

[Fiddlestyx]

Are you building with Center of Mass and Center of Lift in mind (the yellow and blue spheres turned on)? If so, you shouldn't have this problem.

[SkyRex94]

critical for this problem is the position of your REAR GEAR. even if the plane was designed to fly good (CoL-CoM) to lift off you need to place the Rear gears properly.

They are the Angle point of rotation when pitching up during liftoff, so they should be as close as possible to the center of mass, but not on it, otherwise your plane could tip on the back even if standing still. Thats the key to that problem. And you have to watch out that your not too low at the tail, so you didnt smash your engine in the runway during takeoff.

Tip for your craft: It looks way too low at the tail, make the gear make it (nearly) as high as the front. And place the gear just behind your CoM . Try it and it should fly

[cantab]

I'd say on the contrary, if your plane sits on the runway slightly nose-up, it will generate lift in its takeoff roll helping it get airborne. After all, real aircraft using "conventional" landing gear are like that, with main wheels forward of the CoM and a tailwheel at the very back.

Alternatively, you can build in some angle-of-attack on your wings, so they'll give lift when rolling with the fuselage level.

If you have full "freedom" to design your plane you shouldn't need to do things like jettison canards, though if you're constrained by other factors there might be a place for such techniques.

[magnemoe]

I'd say on the contrary, if your plane sits on the runway slightly nose-up, it will generate lift in its takeoff roll helping it get airborne. After all, real aircraft using "conventional" landing gear are like that, with main wheels forward of the CoM and a tailwheel at the very back.

Alternatively, you can build in some angle-of-attack on your wings, so they'll give lift when rolling with the fuselage level.

If you have full "freedom" to design your plane you shouldn't need to do things like jettison canards, though if you're constrained by other factors there might be a place for such techniques.

Yes one tips is to put nose wheel on the center of body and the back wheels a bit outward on body this will tilt the body upwards.

Use two wheels far back and out on wings as caster wheels, to protect engines during takeoff and landing and for stability.

If you use droppable wings they should have an pretty high angle of attack, also mount some seperatrons on them to help during launch, put a parachute to and they can probably be recovered.

[SkyRex94]

But all this uptilting doesn't help you if you'd like to pitch up while still on the runway. for that you need the main gear as a roll angle as i said.

Assuming you generate enough lift already i bet i could make your plane fly and take off brilliantly with just a replacement of the main landing gear

[angeldust]

What about "streamlining" (i. e. ejecting parts of the wing) a spaceplane when reaching higher altitudes? Is that a good idea?

[Alshain]

Well, if it works it works, however, it is a loss. I prefer SSTO's because they have no loss aside from fuel. It is entirely possible to design without any ejecting parts.

As for the comments below, either method of lift off the runway is perfectly acceptable, you can use the wheels as a fulcrum with the pitch as a lever or tilt the aircraft on the runway so it automatically has lift. Just be aware the latter design is a bit more dangerous if you have a long tail.

Edited September 22, 2014 by Alshain

[Rithsom]

Well, if it works it works, however, it is a loss. I prefer SSTO's because they have no loss aside from fuel. It is entirely possible to design without any ejecting parts.

Yeah, this sort of ruins the whole "Single Stage To Orbit" thing. Just be sure to position your center of lift and gear correctly, and you won't even need canards.

[Voculus]

It's a very Kerbal solution!

[Alshain]

I will say this though, on some of my rockets, I've decoupled winglets just to reduce mass before I was ready to discard the stage. However as I grew more experienced I started to time my stages just right so I was done with the stage that had winglets as I left the atmosphere, so the winglets were discarded anyway without special decouplers.

[MalfunctionM1Ke]

Hope this helps you a little

http://forum.kerbalspaceprogram.com/threads/52080-Basic-Aircraft-Design-Explained-Simply-With-Pictures

Edited September 22, 2014 by MalfunctionM1Ke

[Alshain]

Hope this helps you a little

http://forum.kerbalspaceprogram.com/threads/52080-Basic-Aircraft-Design-Explained-Simply-With-Pictures

This is my favorite guide, however he does illustrate vertical asymmetric thrust as being a little more grim than it really is. Don't be afraid to try some of the things he recommends against. However, he's dead on with lateral asymmetric thrust and wheel barrowing. You don't want that at all in any way, shape, or form.

[mythic_fci]

This is my favorite guide, however he does illustrate vertical asymmetric thrust as being a little more grim than it really is. Don't be afraid to try some of the things he recommends against. However, he's dead on with lateral asymmetric thrust and wheel barrowing. You don't want that at all in any way, shape, or form.

True, but if you design properly, you can minimize the effects of lateral asymmetric thrust via SAS control. The engines must be close to the centerline of the COM to reduce rolling and yawing. With proper control, planes can be saved.

[Alshain]

True, but if you design properly, you can minimize the effects of lateral asymmetric thrust via SAS control. The engines must be close to the centerline of the COM to reduce rolling and yawing. With proper control, planes can be saved.

It's pretty hard to design away lateral asymmetric thrust. SAS can help with vertical asymmetry, but lateral almost always sends you into a flat spin and until that thrust is evened out that flat spin will be hard to recover from, at least in the real world. It might be easier to recover in stock KSP.

Vertical asymmetric thrust just forces the nose of the plane downward, SAS can correct it, but if you want to balance it there are various things you can do. You can angle that engine downward toward the CoM or you can make the resting angle of the ailerons raised, so when you take your hands off the keyboard, the ailerons are in a natural pitch up position, thus countering the pitch down from the engines. This is just for jet engines though, the only way I know of to counter rocket asymmetry is with more engines angling against the rotation. Those little orange radials are good for that.

Anyway, that was a little off topic but angeldust, you can see there are many ways to design a plane which is why even in the real world planes don't always look identical. The same is true for KSP and my personal opinion is you should do it however you enjoy doing it. If you like ejecting wings, do it. That's why I love this game, there are no wrong designs. There are more cost efficient designs, there are more fuel efficient designs, there are more balanced easy to fly designs, but none of them are wrong.

Edited September 22, 2014 by Alshain