Does anybody know why spilerons (ailerons mixed with elevators) help to perform high alfa harriers in 3d flying?.
Whats the physical explanation

I'll take a chance on this one.

In such high attack angles, air departs from the wing skin and causes a stall and loss of control. If ailerons are raised (as in upright harriers) the air stays laminated with the wing or at least the stall is retarded, hence better stability and control.

That is just something I have heard and now explained in my simple words...

Actually 3d Joy that is backwards. Spoilerons do exactly what the name implies...spoil the lift. This is why they were invented. Notice the spoilerons deploying on commercial jets when you land. Once they are armed by the pilot the "weight on wheels" or WOW switch activates them once you touch down. This helps to prevent bouncing on the landings and leeps the plane on the ground. Sailplanes use spoilerons to kill the lift and drop altitude quickly.

Now in 3d flight you generally want the wings in a stalled position and you are flying in what is really "vectored thrust" mode; using the engine and large control surfaces to point the a/c in the direction you want. What often happens in harriers with some planes is the wings want to keep flying and they are bouncing back and forth between flying and stalled. Thus the wing rocking. Adding spoilerons kills this oscillating lift and wallah!.......much nicer harriers. Hope this helps everyone!

Thanks Mike... VERY GOOD explanation !!!!...[8D]

Here is my humble 2 cents worth: The need for spoilerons to harrier w/o rocking is mainly a wing design thing. Thinner wings with sharper leading edges stall quicker and at lower angles. Thats why some planes do not need spoilerons to harrier at all, like Caps and even CG Ultimates harrier well without spoilerons. The U-Can-Do type design can be a B---ch to harrier,mainly the transition to get the wings fully stalled. A Do type will harrier w/o spoilerons but you will suffer a lot of rocking until the angle of attack is high enough to fully stall the entire wing,and you must keep it above that point or back to rocking again. That fat ,blunt airfoil has advantages and some drawbacks. Adding spoilerons(and the Do needs a lot)spoils the lift by disrupting airflow on the top of the wing,the transition to fully stalled harrier is smoother,less rocking. There are different ways to get a model plane into a harrier,some simply need to slow down to just above stall and then squeeze in some elevator and its in a harrier/elevator.Aileron on this type of plane is all thats needed to handle a little rocking if there is any. You can pull to harrier at the bottom of a loop,harrier from a hover,from a rolling harrier,even snap to harrier(I havent tried but looks so awesome). The point is,you might be able to get a plane into a harrier without the transition and rocking that usually comes with it,I mostly use the spoilerons if needed.

You are welcome!

Just to add more to the equation: wing rocking can also be atributed to yaw instability. That's class 201 and I'm calling it a week to go play now![8D]

With the huge and tall rudders its hard to imagine that. What is needed is a model airplane wind tunnel so we can hang them from a string and then crank up the fan with smoke added and try flying the maneuvers,then we can see whats up. Are you listening Tower???

OK, to do effective harrier manuvers, typically how much Spoileron is required. How many degrees of spoiler to elevator?
I am considering trying this and would like a good place to start working in this mix

Thanks!

Ken,
Every plane is different. Start small and experiment your way up.
Phillip

The typical U-Can-Do type(very fat with round leading edge) airfoil require a lot of spoileron,I use about 45Deg in the mix and have enough travel left over to have aileron control. I had to make some modifications to get this amount of travel on the Do. This helps a lot getting into the harrier with less rocking but you still have to experiment with each and every plane to find the right amount of elevator,spoileron and throttle setting to lock it in. The down side of using the mix is when you get into trouble, like heading to the ground and you need to pull up quickly,with spoilerons on,the plane does not pull up very well,in that situation its hard to hit the switch off first,I've bashed it a few times that way. I've noticed planes that harrier without spoilerons and had the chance to fly some for a few minutes,they all had more conventional scale like airfoils,thinner wings,more pointy,less rounded leading edges. Caps,Extra,Ultimate Bipe to name a few. My EF Yak would harrier w/o spoilerons but it seemed to require a lot of constant aileron input to stop rocking and lock in. I,ve only experienced 3 or 4 planes that didnt rock at all,harriers are so easy with them,but they werent my planes,they were:
The Monty foamy(TBM I think)
Cap H9 33%
Dave Patrick Extra 29%
Goldberg Ultimate.

Start with no spoilerons, see how adjusting your throttle and elevator change the plane.

The easiest way to Harrier is without spoilerons - as long as your particular plane doesn't want spoilerons.

I was using spoilerons on my CapX, and I could not get that bird to stay steady. After talking to Chip Hyde, I adjusted my elevator throw and turned off the spoilerons, and what a nice Harrier that plane does now!! REAL low, and steady, and without the use of spoilerons recovery is much cleaner.

On the other hand, my Midwest Cap needed a full 1/2" of spoilerons to Harrier.

Some advice -- make sure your engine doesn't overheat. In a Harrier there is less air flow thru your cowl.