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Tail unit formers


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Guest TOSGcentral

There are no particular set dimensions. All these things do is ensure the disturbed airflow separation from fin & tailplane re-attaches to the control surfaces.

 

Make them about 3/4 to 1" wide and about 2 to 2 1/2" deep at maximum section depth. Ensure you have an exactly symmetrical section top and bottom so you do not induce any lifting forces on the control surface! In the case of the two elevator halves ensure that you have exactly matching pairs for each side. You can make each in one piece.

 

Point of maximum section depth should be the conventional 1/3 back from leading edge.

 

You need two in each surface (you could put three in if you wish) and evenly space them out. As the control surfaces are tapered each will be a different length. Notch the leading and trailing edges so they interface with the tubular frame and tape them securely in position with ducting tape so they do not slip out of the taper. Then stick the skins back on and tension as normal.

 

These are not structural items in terms of taking any loading - they are purely for shaping. So any rigid foam (preferably skinned each side for durability and stiffness) that is really light will do.

 

The effect on handling and control power is remarkable. It is like fitting power steering! Once you have tried them you will never want to go back!

 

Tony

 

 

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Thanks Tony. Has anyone made them the full length /width so that the control/stab surfaces are foil shaped and all you do is add the outer skin [fabric] . Something like a cessna 150 ?

 

Cheers Alan

 

 

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Guest TOSGcentral

Not to my knowledge and would be an expensive 'overkill' anyway.

 

You just have to make the control surfacers deeper than the leading fixed surfaces to re-attach the airflow.

 

Besides which what you describe would be going out of 95.25 ordinance and is unnecessary anyway! Just two or three formers in each surface does the trick and remains kosher according to the 'factory'.

 

T.

 

 

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