adjusting the amount of roll on airplanes?

[Belphegor]

hello,

is it possible to adjust the amount of roll on winged aircraft somehow? i don't have all parts yet in carreer mode so i usually end up sticking a standard control surface to that wing that comes without control surfaces. the problem is that the rolling motion is.. well.. violent. usually a small tap on the Q/E key rolls the vessel almost 90 degrees so i always end up over-shooting the runway while trying to level out the plane for landing :/

could i be doing something wrong during the build? i always try to get the center of lift just in front and a little above the center of mass. i tried lowering the center of mass but there is only so much i can stick to the bottom before it starts scraping the ground on take-off

thanks

Edited August 18, 2014 by Belphegor

[diomedea]

I would suggest to use precision mode (activated by pressing Shift-Lock) if the commands are too rough. But I agree, too big control surfaces on the wings is the cause of your issue. About building a plane, better to place the CoM slightly in front of the Center of Lift, it helps to recover from a stall.

[Belphegor]

nice! didn't know there was a thing like 'precision mode'.. and yes.. i just looked trough a plane tutorial again and realized i've been doing the Com/CoL thing wrong

looks like i have to gather some more sciene then.. thanks

[Pecan]

diomedea has identified the most likely culprits. If that's not enough you can try moving the control surfaces closer to the CoM. The further they are from the CoM the greater the 'control authority' (strength) they will have. Specifically, if they are on the outside edges of the wings, move them inwards so they are nearer the fuselage. Similarly, with elevators, if you are pitching up/down too violently you can move them forward so they are nearer the CoM.

[cantab]

Other things to consider:

Are you sure you don't have the smaller control surfaces? Wiki lists them in the same tech node.

Try moving the ailerons closer to the middle of the wing.

Which control surfaces are affecting roll? You can right-click them and turn various functions on or off. For example if my plane has separate ailerons and elevators/canards, I like to ensure they control only roll and pitch respectively.

Do you have pod or reaction wheel torque on? Try turning it off. Alternatively, try turning it on and disabling aerodynamic roll control, relying just on the torque to roll your plane.

[Belphegor]

that's some usefull information there.. thanks Pecan, thanks Cantab

i put the control surfaces near the tip of the wings. i'll put them closer to the hull i don't think i have the small control surface.. i'll check that when i get home.. i might just hit myself in the head if they are in the parts list and i looked over them the entire time..

for the sake of simplicity there are only 3 of them on everything i've built so far.. one on each wing, and a tailfin. i like that idea, turning off roll on the main wings and using some winglets to roll the craft instead. i'll try that.

cockpit torque must have been on.. didn't even think about that..

thanks i'm sure these little adjustments will make a big difference! you saved many kerbals from certain death today

[impyre]

I'd like to mention a couple things here. I use my main flaps for pitch control only, and use a smaller vertical tailfin to control yaw, and two small canards mounted near the front for pitch+roll.

Edit: removed inaccurate info.

Edited August 18, 2014 by impyre

[cantab]

I would expect a deflected control surface to produce a fixed maximum force. How much torque that force then generates depends on the distance of the surface to the CoM. KSP aero being KSP aero though I may be wrong.

[Pecan]

...edit: I don't think it matters where the flaps are in relation to the axis of roll...

cantab is, as usual :-), correct. See http://forum.kerbalspaceprogram.com/threads/52080-Basic-Aircraft-Design-Explained-Simply-With-Pictures

[GoSlash27]

In addition to the above suggestions, I'd recommend a little dihedral on the wings. At least the outer portions. It won't reduce your roll response any, but it will make your aircraft want to self-correct to wings level, so you won't have to roll as often.

Best,

-Slashy

[Belphegor]

okay.. after a few hours of crafting numerous paper airplanes with differently angled 'control surfaces' in various locations i have come to the conclusion that aerodynamics are confusing.

dihedral.. had to google that. i'll try it thanks

[Pecan]

...aerodynamics are confusing.

Yeah, but hey, at least it isn't rocket science *grin*

[Belphegor]

nice one

6 part orbital space station.. no problem. but a simple take off, turn and landing with plane results in persistent failiure on my part. i love this game

edit: thanks guys i followed the advise and the airplane is a lot more stable now. i noticed a little airstrip on the island near KSC and went for it. so much easier now without the excessive rolling

Edited August 19, 2014 by Belphegor