First plane attempt- Suggestions/Improvements?

[Panzerbeard]

This is in the correct section, right? It seems like the right section. Sorry if this is not, in fact, the right section.

So, I've never really touched SSTO's, Spaceplanes, Planes, Helicopters, Giant Catapults or indeed any other form of atmospheric travel in KSP before, and I thought I'd give it a shot today. I'm not looking to make a spaceplane yet, just a good-old regular plane I can use for exploring Kerbin and buzzing farmers (look, I can pretend, ok?). After a bit of trial, error, and burning, I came up with this little thing, that seems to fly reasonably well. (that is, it stays in the air and doesn't evaporate when I try to turn it).

My first issue is this: while it keeps a heading more or less perfectly on its own, the nose wants to dip down a few degrees whenever I touch the controls- even a minor roll will drop the nose down and force me to readjust it. I thought this would be a CoL/CoM problem, but the CoL IS slightly behind the CoM (that's half the reason why I have so many wings on the back. The other half is that it looks cool. Obviously.), so I don't know what's causing it.

Secondly, the turning is very twitchy and jerky, even with precision controls turned on (I use a 360 controller for flying; left analogue stick for pitch/yaw, shoulder buttons for roll). I tried removing the control surfaces from the upper and lower wings, which helped a tiny amount, but it's still not very smooth. This might be exacerbated by my first problem, though.

Also, any general flying tips? Specifically, turning and landing. For turning, I've just been rolling to a ~90 degree angle, and gently pitching up, which I assumed would be the best way of doing it. And although I can land 5 times out of 10 on flattish ground, if I'm lucky, I seem to take about 5x the length of the runway to do it. I'm not sure if it's just incompetence, lack of practice, or some vital flaw in my plane design or flight technique.

Cheers,

Ash.

Edited October 21, 2013 by Panzerbeard

[boomerdog2000]

May want to add a vertical stabilizer just for good measure. Other than that all I really know is keep the center of lift behind the center of mass and burn until you hit orbit.

[Cal'Mihe]

I second the vertical stabilizer. You basically have no yaw authority, and depend on the reaction wheel for yaw. The twitchyness is because your roll authority is way overdone, with a plane that size, you could make do with just a single set of the small elevators and it would roll fine.

For landing, what speeds are you normally comming in at ? Depending on the amount of lift you have availiable (lots in your case), you should be able to do a glider landing at 50 m/s forward and -4 m/s vertical. I generally try to touch down at less than -5 m/s and everything stays together.

[Panzerbeard]

Thanks for the replies, guys.

When you say "vertical stabilizer", do you just mean a tail fin/canard?

Also, how important is yaw, for atmospheric flight, just out of curiosity? When should I be using it as opposed to just rolling and pitching?

Sorry if I seem incredibly noobish here- I can put sattellites into a Moho orbit or land on the Mun easily, but the humble aeroplane has bested me

For landing' date=' what speeds are you normally comming in at ? Depending on the amount of lift you have availiable (lots in your case), you should be able to do a glider landing at 50 m/s forward and -4 m/s vertical. I generally try to touch down at less than -5 m/s and everything stays together.[/quote']

I've been overcautious with the landings and wobbled a few metres above the ground until I was at about ~40m/s. I've been practising a bit more since I made that post and can land reasonably well now- I managed to land on the runway at the abandoned airstrip island, so I think that the landing issue is more inexperience than anything else

[Lohan2008]

When you say "vertical stabilizer", do you just mean a tail fin = YES

I use the winglet: tail fins let you turn left/right (yaw).

2> KSP is not a flight simulator. The game engine is very twitchy / as wings do not use real world math...

Edited October 19, 2013 by Lohan2008

[arq]

Use the small control surfaces, and only one or two pairs at that. Actual yaw control surfaces are not very important, but having some vertical stabilizers (a 'tail') is important for keeping your plane pointed prograde in the yaw axis (actually I don't even add control surfaces to my vertical stabilizers ('rudders') any more, they get used in roll maneuvers which tends to annoy more than it helps for pitch.

If your plane is pointing down too much when you bump the controls, it is because the SAS gets temporarily disabled. This happens because the CoL is behind the CoM, so naturally the plane wants to pitch down. Moving the CoL forward just slightly should reduce this.

[GraviTykillz]

making sure to ck your mass and lift and icons.

Lift should be @ center of mass.

[boomerdog2000]

Lift should be behind center of mass. If it is at center of mass your plane is going to be very unstable.

[Sovek]

Lift should be behind center of mass. If it is at center of mass your plane is going to be very unstable.

Actually I've found that COL has to be very close if not at the same location as COM, otherwise the nose falls and will continue to do so, proving nigh impossible to keep under control. Conversly, if COM is behind the COL, the plane WILL pitch up, and any attempt to correct it at speed will fail.

Trust me, I've spun out too many times this past week trying to get a plane to orbit. I've done it, but its not easy.

[Cruzan]

Most of the possible problems have been covered, but something else to consider is that your CoM and CoT (thrust) likely aren't perfectly in line due to how heavy those landing gears are. It's a common problem for planes to have the CoM brought down slightly due to those gears being mounted on the belly of the plane. This puts the thrust above your CoM, making your plane want to nose down constantly. You can counter this by trying to get the gears as close to level with your CoM as possible, or putting weight on top of the plane to compensate, such as RCS pods and whatnot.

For fine roll control, 1-2 sets of the small control surfaces are good and you can mess around with how far out you put them on the wings as well which will change how much of an effect they have. Further away means twitchier responses. Closer to the body means smoother responses.

If all else fails, slap more SAS units on there! They're the secret to making just about any design work haha

[Panzerbeard]

Thanks very much, all, I've made a few changes based on your suggestions and it all works much better now