Space plane Frisbee's at low speeds need help

[jj5437]

As said in the title at low speeds my plane doesn't function right it will stay straight for a while and any attempt at turning or lifting without a speed increase will cause it to spin to the left or right. It will spin 2-3 times before it stabilizes in the opposite direction to what it was originally facing. The plane may seem poorly built to a lot of you veterans but i would like to see it work none the less. Any suggestions would be helpful.

Side note, The spin is not caused by flame out as it happens even at low altitudes and none of the engines turn off, and the plane works perfectly fine at 325 mps and above.

[sal_vager]

Hi jj5437, you might like to check out this thread, it's a little old but still very useful, and KSP's aero and drag models have improved since so planes fly even more like they should

[BenG]

Any pictures? Sounds to me like you need a vertical stabilizer (tail fin) for directional stability.

[cantab]

Bigger vertical stabiliser, aka tailfin, at the back to stabilise the plane when it slips sideways.

If you're using FAR, you could also be having the centre of lift shift around with Mach number. Usually it will shift backwards at supersonic speeds which makes your plane more stable but might cause a nosedive, but it's possible an unusual design would have the centre of lift shift forward destabilising the aircraft.

[TheXRuler]

Also, if you are going for a tailless designg try using slightly dihedral wings

[Van Disaster]

Would probably put cash on insufficient yaw authority. A stage practically everyone goes through is not enough vertical stabilizers.

[Venusgate]

Basically, you're engines don't want to push your fat*** plane and want to fly on their own. If you have wings, you have all the pitch stability you need. If you don't have enough tailage, you've got nothing but the wee SAS in your cockpit telling your engines to behave.

If you want to keep tailage low, consider putting some SAS over the CoM - that way it's much more optimized. It doesnt really help taht you may have a terrible design, but it will save your asthetics if you can put them in a Mk2 service bay or get a mk2 shaped SAS module.

[Gahooligan]

A standard tail fin or a wing with control surfaces will do the trick for ya. Place it near the back, behind the center of gravity.

It should be smmoth fling after that.

It's interesting though that at hish speed, its stable. Could you upload a screenshot perhaps? id love to see what youre workin' with.

[GeneralVeers]

A good way to avoid the spinney outey in a turn is to fly the way fighter pilots generally do. Instead of using the rudder, roll about sixty degrees in the direction you want to turn, then pull up on the stick. Very stable and also usually gives you faster turns. Has the added benefit of looking badass!

[TheXRuler]

A good way to avoid the spinney outey in a turn is to fly the way fighter pilots generally do. Instead of using the rudder, roll about sixty degrees in the direction you want to turn, then pull up on the stick. Very stable and also usually gives you faster turns. Has the added benefit of looking badass!

Wait so you mean there are other ways to make a turn? I use this technique for everything, including my 350 odd ton spacplane xD

[GeneralVeers]

Yup, there's more than one way to make a turn......perhaps you'll TURN over a new leaf....?

(so, wait--by "I use this technique" do you mean rudder turns, or my roll-and-pull-up method? ambiguity + nitpick = me)

[cantab]

The vast majority of aircraft should turn by banking, which allows the lift from the wings to pull them round. If you fly without SAS you just need to roll to your desired bank angle and the plane will turn naturally. If you're using SAS it will fight that natural turn so you'll need to guide the plane round yourself.

For a more aggressive turn, bank steeply and pull up, that's the "fighter jet" approach.

The rudder is used to control sideslip - whether the plane's nose is in line with the airflow or not - and not to make turns. That was the crucial discovery and invention of the Wright Brothers.

Exceptions where you would turn with the rudder include an emergency where roll control is unavailable, steering on the ground, making *tiny* course adjustments, and some unusual aircraft types that are designed for rudder steering.

[TheXRuler]

Well say I need to make a 45 degree turn. I'll roll the entire 300 tons by ~70° and then pull up hard. That big*** spaceplane can pull like 4g's when subsonic. Really usefull for decelerating during reentry. (it really was rather ambiguos )

[Van Disaster]

Turning by yawing will generally result in a banked turn anyway in a properly built aircraft, because to be stable it should roll out of sideslip. I'm struggling to think of a real aircraft that turns without banking though, deliberate sideslip is usually reserved for losing speed/altitude or landing crosswind.

Obviously if it's built to be unstable then it's not going to do this

Edit: talking real life/FAR, no idea if stock aero deals with changes in lift due to yaw.

Edited November 3, 2015 by Van Disaster