Is this FT3D behaviour correct?

[nickf]

Hi,

I have been getting more courageous with the things I have been trying with my FT3D.

One of them is to see what happens with full rudder (at quite low speeds), with a bit of up and ailerons normal. I expected it to do a 'flat turn' as dictated by the rudder, but it rolls out of the turn in the opposite direction (and does this in for L or R rudder turns)!!! ?? The rudder has alot of authority (full throws) and works a treat in all other respects, stall turns etc.

I believe the plane is set up neutrally based on the online guides and advice from this great forum, any ideas what is going on as presumably this is not normal?

Thanks nick

 

[ElectriSean]

Try giving opposite aileron input to keep the plane flat.

 

[nickf]

Try giving opposite aileron input to keep the plane flat.

Hi, thanks for the reply!

I did try assisting the turn with some aileron in the same direction to encourage it into a flat spin, but it suddenly snaps into a normal spin (in the direction of the rudder with aileron assistance). Won't opposite aileron encourage it even more to roll out of the rudder controlled turn?

nick

 

[Namactual]

It's really hard to tell what is happening without seeing it.

If I understand what you are saying I would guess the Rudder being so large and above your CG it is actually causing a rolling moment itself. If this is the case, you will have to apply more aileron to counter the roll with a little more speed.

You could always modify the plane too. Make the rudder just as large below the centerline as the top.

 

[Hai-Lee]

When doing a flat turn the wing on the outside must be travelling faster than the wing on the inside of the turn. The wing travelling faster will generate more lift than the slower wing and tend to rise up or the slower wing will tend to have less lift and fall.

This difference in lift will cause the aircraft to roll as it turns. This is the way that 3 channel aircraft actually manage to turn but their increased dihedral allows the turn to be managed or controlled.

It is normal on all conventional aircraft to require some countering roll control input if a truly flat turn is to be accomplished.

If you fit a stability controller then the roll input will be applied automatically by the controller as you apply the rudder only.

Have fun!

 

[nickf]

Thanks very much. Looking at the the FT3D vids,, they did quite wide flat turns. I think It was just pushing it too far!

 

[Bricks]

When starting a flat spin for me at least I cut throttle back input rudder and opposite ailerons to keep it flat and start to give more throttle as the planes starts to flat spin faster, let up on some aileron and input some up elevator.