Plane design for automatic recovery from a graveyard spiral

[delta wee]

Right now I have a plane that starts to go in a spiral when power is turned off, and never recovers from the spiral by itself. What kind of plane design would be able to automatically recover from a graveyard spiral without power so that it ends up pointing in the prograde direction?

[GoSlash27]

Sorry, can you elaborate? What does your "graveyard spiral" look like? Is it like a flat spin, or attempting to fly backward, or just slowly rolling?

Best,
-Slashy

[OHara]

Dihedral in the wings is the classic solution.  

First, though, if you have a large vertical stabilizer on the tail, you should try to reduce its size. and make sure it is above the center of mass so it gives a little bit of correction to roll.

When the plane slipping to the side, there are forces that make it yaw into the relative wind, and those that make it roll away from the relative wind.  If the yawing forces are relatively larger, you spiral. With the center-of-lift and center-of-lift indicators turned on the in SPH, you can select the root part and shift-A to yaw it 5°, and see how the moved center-of-lift is trying to turn the craft. 

 

[Helmetman]

@OHara Very true about the dihedral effect.

I just want to add to this that anhedral wings provide dihedral effect to meet the very same purpose. Some people have their wings on the top, and a anhedral angle on the main wings will also give the same effect.

When being asked these kind of questions I always prefer a picture of the craft in the SPH with the Com, Cot and Col indicators with a panoramic view of the aircraft. 
This will tell us more (something) 
Now I or anyone else is just guessing about the solution.

Edited November 18, 2017 by Helmetman

[delta wee]

Here are some pics of my plane. It's a space plane so has no propulsion and I want it to glide stably on re-entry.

[GoSlash27]

Yeah, I can see how that would want to fly backwards. The empty mass is centered longitudinally well ahead of the center of lift, but you have a large, draggy, light structure in the front. You would need a lot more drag in the back to compensate for that. Maybe clamshell airbrakes?

Best,
-Slashy

[delta wee]

17 hours ago, OHara said:

Dihedral in the wings is the classic solution.  

First, though, if you have a large vertical stabilizer on the tail, you should try to reduce its size. and make sure it is above the center of mass so it gives a little bit of correction to roll.

When the plane slipping to the side, there are forces that make it yaw into the relative wind, and those that make it roll away from the relative wind.  If the yawing forces are relatively larger, you spiral. With the center-of-lift and center-of-lift indicators turned on the in SPH, you can select the root part and shift-A to yaw it 5°, and see how the moved center-of-lift is trying to turn the craft. 

 

Thanks, making the wings dihedral works.