How to make tail struts?
 

I would like to make a set of supporting tail struts for an edge 540 with a 66" span. The use of this plane will be limited to sport flying and imac sequence practice. I have a couple of questions I am hoping someone could help me out with..

1. How does one determine the appropriate length of each strut? Is there some formula to use involving the width of the horizontal stab?

2. Are 2-56 or 4-40 pushrods better for this purpose?

3. What is the best way to connect the rods to the fuselage and the horizontal stab?

4. Shoul I put struts on both the top an bottom of the stab? If so, how/where should I connect the top strut in the middle?

5. What is the best way to make a hard point on the fuselage/horizontal stab for the rods?

Thanks in advance!

RE: How to make tail struts?
 

I just used this kit on my Vectorflight Extra 300S 66 inch. http://www2.towerhobbies.com/cgi-bin...?&I=LXFV30&P=7

I used the kevlar instead of the wire due to weight, and radio interference.

""1. How does one determine the appropriate length of each strut? Is there some formula to use involving the width of the horizontal stab?""

I just used the triangle that I used to mount the tail, for marking purposes, and came close to the middle of the stab.

""2. Are 2-56 or 4-40 pushrods better for this purpose?""

Answered above.

""3. What is the best way to connect the rods to the fuselage and the horizontal stab?""

Use this kit, it has all that you need.

""4. Shoul I put struts on both the top an bottom of the stab? If so, how/where should I connect the top strut in the middle?""

I did, I wanted to connect the whole thing together for strength. Yes in the middle.

""5. What is the best way to make a hard point on the fuselage/horizontal stab for the rods?""

There should be plenty of places to put the kit on, just use some CA to make the holes that you drill sturdier.

See Ya,
John

RE: How to make tail struts?
 

For optimum strength, place the attachment 2/3 of the span out from center. If you are using rigid struts, you can sometimes omit the lower (underside) struts and you use both the compresive and tensile strength of rigid struts. If you use wire or kevlar, you must use both upper and lower flying wires for them to be effective as they work only in tension.

RE: How to make tail struts?
 

To put in hard points just glue in some bass wood or plywood where you want the wires to attatch. Just figure out where you want them and add the parts.

Mark Shuman

RE: How to make tail struts?
 

Carbon fiber rods epoxed to tail is how i did it.

RE: How to make tail struts?
 

Struts top and bottom are your best choice IMHO because they are lighter for the reason given by Rodney. (I prefer wire)

If you want to brace just the top (or bottom) I would sugest some airfoil shaped tubing that is availabe at many LHS's. It would give you better stiffness at lower weight than solid rods. The struts on many FS such as the Piper Cub and all single engine Cessnas are tubular. They are in tension during flight, but under slight compression on the ground. They need to be stiff beause a hard landing could put sizeable compressive loads on them.

On a related topic, this is why many of the early airplanes, starting even before the Bros. Wright were biplanes. Stiffning the structure with struts and cables in tension was much lighter than a cantalever spar would have been back then.