What's wrong with my plane?

[thestuff]

So I've read a lot of tutorials about making planes, but I can't seem to be able to make one work...

Here is one I tried to make. I try putting moving the center of lift closer or further from the center of mass, but can't find any spot that works (either the plane doesn't take off, or it spins upward). I'm sure there is some other conceptual thing I'm missing, buy I don't know what.

Thanks!

[MaverickSawyer]

You need some sort of pitch control. I'd advise a set of canards and pull the wings aft. You also have WAY too much yaw authority with that tail. With a bird that small, a fixed vertical stabilizer is good, since the command pod torque can give you your yaw control.

[Alshain]

Yep, no pitch control. A plane needs either elevators or elevons, since your plane is not a delta wing, elevators it is. Elevators should be as far from the center of mass as possible for optimum pitch control, while ailerons should be in line with the center of mass and far out on the wing tip for optimal roll control. Finally, either use smaller wings (or even winglets) or make your plane a little longer. You have too much lifting force there for such a small plane and it will make it heavy. Make sure you also right click each control surface (including winglets and tail) and set their desired function. Most times it will work anyway, but sometimes it does weird stuff. Elevator = pitch, Ailerons = Roll, Tail = Yaw.

I have Ven's installed but you should be able to get the basic idea from this (the control surfaces on the inside wing are flaps, not ailerons):

Edited September 4, 2015 by Alshain

[thestuff]

It flies! Thanks!

[mrclucks]

i know you fixed it, but i think you might be able to get it to fly better/faster/stronger if you take off all wings and place a small delta wing, add a small elevator and a small aileron and then position the delta wing so the center of lift is roughly where you have it now.

i'm just spit balling so dont take my word, it just seems like it might be better

[tbarcello]

i know you fixed it, but i think you might be able to get it to fly better/faster/stronger if you take off all wings and place a small delta wing, add a small elevator and a small aileron and then position the delta wing so the center of lift is roughly where you have it now.

i'm just spit balling so dont take my word, it just seems like it might be better

You see, it is not going to work. Look at where the fuel is. When drained, CoM will go back to engine. And CoL will be in front of CoM. So it will fly, just not far.

Switching places between materials bay and tank would solve this.

[Kryxal]

Actually, I don't see the CoM moving all that much ... but it's best to see what happens if you drain all the fuel out. You might want to remove the oxidizer too if you haven't already, unless you need it for stability purposes. It's also worth making sure the forward control surfaces are disabled, just to be safe.

[tbarcello]

Actually, I don't see the CoM moving all that much ... but it's best to see what happens if you drain all the fuel out. You might want to remove the oxidizer too if you haven't already, unless you need it for stability purposes. It's also worth making sure the forward control surfaces are disabled, just to be safe.

Yeah, you are right, there's oxidizer. But it will still move back, and the suggestion was to put CoL slightly behind CoM.

[Val]

Actually, I don't see the CoM moving all that much ... but it's best to see what happens if you drain all the fuel out. You might want to remove the oxidizer too if you haven't already, unless you need it for stability purposes. It's also worth making sure the forward control surfaces are disabled, just to be safe.

Agreed! The cockpit and engine roughly balance each other out in this design. I don't see CoM moving much either.

And he did remove the Oxidizer. Look at the resources tab at the bottom of the pic.

[cantab]

In the latest design the centre of mass is near the middle of the (only) fuel tank. That means CoM shift will be small.

And yeah, when it comes to your first planes I would say keep them fairly conventional. So have main wings, a tailplane at the back, and a tailfin. Tailless designs, with or without canards, are harder to make fly well.

[Claw]

It's also important to remember that a new player managed to fix his plane in his own way with your help. Don't forget to recognize that.

Nice job on the little science bird, TheStuff...and welcome to the forums!

Cheers,

-Claw

[Alshain]

My mentality is to give them the basics and let them learn on their own, unless they ask for more. I don't expect their first flyable plane to be pretty or perfect... just flyable.