Tip Stall
 

Can someone please explain exactly what "tip stalling" is, how does it happen, and how do you prevent it. I have read many one liners about it (the tone of the lines suggest it is a bad thing), but I have not read any real explanation of just what the phenonen is. Thank you all in advance.

Max

RE: Tip Stall
 

Stall:
The wing needs a minimum airspeed to create enough lift to keep the plane in the air. The wing is tilted upwards slightly (angle of attack) to create more lift. At low speed the angle of attack needs to be higher than at high speed. When a certain angle of attack is reached (normally 16-18 degrees) the wing stalls. It quits producing lift. When this happens, the plane will quit flying and start falling. This is what happens when you go too slow and hold full elevator to try to keep it flying.

Tip stall:
In some cases only one wing half stalls. One wing will drop because it lost lift (this happens fast). One situation that might create a tip stall is; you are flying very slowly, just above stall speed. You apply full aileron. The aileron that moves down will make the effective angle of attack higher, and stall the wing half. The other wing half will not stall because the aileron going up makes the effective angle of attack smaller.

To sum it up; tip stalls are stalls where only one wing half drops (instead of both wing halfs in a "normal" stall). Full aileron deflection at very low airspeed is one of the things that can cause a tip stall. Tapered-wing, highly aerobatic planes tip stall "easier" than trainers.

RE: Tip Stall
 

sandal has a good explanation. I will just add that it nearly always occurs when there is a yaw introduced at the moment of stall. Use of ailerons in slow flight without coordinating rudder will cause one wing to drop suddenly due to the adverse yaw introduced by aileron deflection. Also flying with rudder only near the stall increases chance of "tip stall". To reduce the tendency to drop a wing, especially on trainers, the designer sometimes specifies a small amount of "wash out" which is a twist of the wing so that the root portion stalls first. This isn't desirable on a stunt ship as it makes inverted flight more difficult and interferes with good snap maneuvers. Usually tip stall isn't a problem with a rectangular wing since it naturally tends to stall from the root out. A sharply tapered wing tends to stall at the tips first making tip stall likely.

This assumes that the wing is built straight and true. A wing with even a slight warp built in will tend to drop a wing at the stall without warning. This is often mistaken for actual tip stall.

RE: Tip Stall
 

Two good explanations, and yes, it happens fast and yes it's a bad
thing. Especially at low altitude. Hard to recover quickly enough.

tommy s

RE: Tip Stall
 

Most tip stalls occur at take off, the pilot applies to much up elevator before the plane has had a chance to build up enough speed to provide the needed lift.

RE: Tip Stall
 

Rudder use INSTEAD of ailerons is the way to help avoiding the tip-stall when needing to do a turn at low speed.

The ailerons at low speed can create adverse-yaw. (drag of the lowered aileron opposing the desired direction of the turn.) This effect can in some cases overpower full rudder being used to aid the turn. When that happens, the tip stall will be immediate and will always result in a spin. (sometimes flipping hte aircraft inverted for an inverted spin)

Low speed turning control... use the rudder. Using the ailerons at stall speed can cost you the airplane.

RE: Tip Stall
 

OK guys---got it. Really appreciate your responses. Pretty much what I thought but I had never seen it put into words before. Very judicial use of the ailerons, or no use at all, on climb out is the ticket, huh? Thanks, guys.

Max

RE: Tip Stall
 

Hi!
Lots of good info...but it is vital that you understand that light weigt is of vital importance to avoid any stalling of the wing.
Trainers and scale airplanes (Spitfires and the like) benefit from having wash-out in the wingtips!

Regards!
Jan K
Sweden

RE: Tip Stall
 

I will agree with a wing with Dihedral. For a aerobatic or flat wing, this may not always be true.

RE: Tip Stall
 

Then what can I do to avoid the stall on landing,even tho the plane still has flying speed.I've ask this question in other post but got no response.
The plane flies great except for landing.It takes a hard right hook on landings.I realize that too slow will stall but I tried to bring it in faster and it still stalled.
What changes can I make to stop the stalling.Can I program something in my 6XA to help or am I stuck with a stalling plane..It's bound to get torn up if this keeps up.

Thanx
Walt

RE: Tip Stall
 

Check carefully for a warp in the wing. If it hooks to the same side each time and it is not really slow I would suspect a slight warp. If it is a trainer type with a rectangular wing and not overly heavy, it’s not likely “tip stall”.

RE: Tip Stall
 

If you're having troubles with stalls on landing approaches, then you really are slowing down too much. Don't hold so much up elevator during the descent, let the nose stay a little lower, and pull up closer to the runway.

My over-weight CAP would tip stall very quickly and was rather nasty about it. To land it, I'd almost dive at the end of the runway, then pull out and fly down the runway few inches up, and let the plane settle on to the wheels. No long, nose-up descents with that plane.

RE: Tip Stall
 

Also, check the CG. If the plane is too nose heavy, it will tend to need to fly faster. More up elevator is needed to overcome the nose heavy condition. This can cause the plane to stall at a higher airspeed. Remember, stalling airspeed is not a constant.