RCU Forums - Incidence question

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Incidence question

Hi all

I am busy putting a new horizontal fin on my Stick 60 and want know what the effects are of adjusting the incidence of the horizontal fin. (i.e what will the effect be if the horizontal fin has a bit of positive incidence , will it pitch up or down?)

Previously I had just glued the horizontal fin without worrying about incidence.Before I had to fly with quite a bit of up trim which I think is becasue the wing's incedence was slightly negative.That I can fix if I have to, by putting foam under the front of the wing.But before I glue the new horizontal fin in place I would like to know wether I should give it a bit of negative incidence or just make sure that it is parallel to the thrust line and then adjust the wing's incidence to make the plane fly level.Before I had lost a lot of travel on the elevator because I think the incidence was not right.I know that the C of G may also effect the pitching of the plane,but that I have set to be slightly nose-heavy).

Thanks!

RE: Incidence question

Quote:

ORIGINAL: TuNeD PiPe

Hi all

I am busy putting a new horizontal fin on my Stick 60 and want know what the effects are of adjusting the incidence of the horizontal fin. (i.e what will the effect be if the horizontal fin has a bit of positive incidence , will it pitch up or down?)

>Positive incidence on the horizontal fin will cause it to pitch down.

>If no incidence is called out on the plans or in the instructions,
>set the incidence to 0 on the main wing and 0 on the horizontal fin.
>The main wing and horizintal fin should be parallel to the thrust line when
>setting the incidence.

Previously I had just glued the horizontal fin without worrying about incidence.Before I had to fly with quite a bit of up trim which I think is becasue the wing's incedence was slightly negative.That I can fix if I have to, by putting foam under the front of the wing.But before I glue the new horizontal fin in place I would like to know wether I should give it a bit of negative incidence or just make sure that it is parallel to the thrust line and then adjust the wing's incidence to make the plane fly level.Before I had lost a lot of travel on the elevator because I think the incidence was not right.I know that the C of G may also effect the pitching of the plane,but that I have set to be slightly nose-heavy).

Thanks!

RE: Incidence question

I'm not familiar with the Stick 60, but if it has a flat bottomed wing, a bit of negative incidence in the wing can improve its agility, particularly in inverted flight. Negative wing incidence is an old trick for making flat-bottoms stunt well. However, the stab should probably be at zero incidence.

RE: Incidence question

I presume you are talking about the Big Stick 60.

The incidence for both wing and stab ought to be 0. Prop your plane up so the wing is level. Use an incidence meter or measure from the table to the center of the leading and trailing edges. Once this is level, you can adjust the stab.

It is fairly common for Sticks with a high wing and low stab to need a little up elevator trim. It shouldn't be excessive, however.

You might want to check the CG. If you are nose heavy, you'll be carrying extra up elevator. As I recall, most Sticks build nose heavy. I use a Big Stick 40 for an airborne engine break-in plane and I put the rudder servo in the rear to help with CG. I also added 2-56 rods from the fin to the stab tips to keep the stab from breaking off. Seems to me it is just glued on the bottom. A better method would be to have it mounted in a slit halfway down the rear of the fuselage.

Another thing you should notice in the air is planes with low mounted stabs are more sensitive in down elevator than in up. The up movement is into disturbed air so it isn't as effective. Outside loops will be tighter than inside ones with the same elevator movement.

RE: Incidence question

Thanks to all for the info!

I glued it on with 0 incidence and moved the c.g a bit backwards.The wing is symmetrical and does have a slight negative incidence.I tried it today and it feels like a different airplane much more maneuverable than before.There was a very strong cross-wind so it was actually a lot of fun because the plane would literally just hang in the sky even with the throttle at idle.

By the way, the Stick is V-Stick 60 made by V-mar.They are really cheap and low quality but good enough to have fun with.
The reason why my old horizontal stab broke off was because it just popped off when I was cleaning it.I used better epoxy this time because it seems the fuel made the epoxy go soft therefore weakening its strength.