Elevator/Rudder Linkage Wt. Question

[TIA]

Hey guys!

I'm finishing up my Spirit Build and want to keep the plane light as possible. My question is regarding the linkage going from the servo to the elevator & rudder. It's very long and I want to know if anyone has any tips or tricks to what works well and is minimal in weight?

Would I want to go with carbon snakes or plastic Sullivans? The old fashioned balsa with wire ends method?

TIA.

[alstrahm]

TIA, I have three Sagittas and they all use the sullivans, I use the .056 in. brass cable with the plastic housings, very versatile as you can snake them around, on the Saggita elevator you need to J them up to the elevator, and they are light and strong. Just my 2 cents worth.
Allen

[LVsoaring]

I use CF pushrods.... can't remember the size, either .065 or .072, but whatever the standard brass couplings will fit.

I start by installing the outer pushrod housing from a set of ny-rods into the airframe, keeping them as straight as possible.

Next, I cut a number of pieces of inner ny-rod about 3/4 inch long. I space these evenly along the CF pushrod. Lastly, after measuring everything, I glue the inner ny-rod pieces to the CF pushrod with thin CA, and glue the brass couplers to the ends. A word of caution here, make sure you clean the couplers in acetone first, and then scratch or score the inside where the pushrod slips in. This is critical to get a good bond. Glue the couplers with thick CA, or that black rubbery CA. Then, slightly crimp the coupler to give some added security. (Ask me how I know this!)

The result of all your efforts will be a pushrod that is stiff but still a bit flexible, and has very little friction. The inner nyrod pieces keep the pushrod centered inside tghe outer tube, and prevent slop from flexing inside the tube. Since the contact area is very small (just the inner ny rod pieces touch the outer housing), there is very little friction. I have been using this set up for years with great results. The picture should make it very clear.

[glidermang]

TIA:

I have used all that you mentioned, and all are time-honored, reliable ways to go.

I use a lot of Sullivan pushrods, #507, just for the convenience. I've probably used a hundred yards of them. You can solder one end and Z-bend it; the other end you can solder or epoxy on a clevis.

Guys like ASK at RCBuilder.com will sell you their DLG control rods, which are stainless steel wire inside teflon tubing. Very light, strong if supported all along the length.

Properly made, however, and balsa stick pushrods with wire ends are as light as anything, and absolutely rigid.

Go for it!

Yours, Greg

[target]

Balsa is not very rigid, I would go for the CF rods, and you might try gluing just the Nyrod yellow inner into the fuse as the housing to a .060" CF rod. #111 Dubro couplers fit perfectly, but to be honest, I just glue and bind a quality nylon clevis (MPJet only, with the brass pins) or a ball link yoke to the tail end of the CF rod. This is THE LIGHTEST setup you can use for the tail end.
Then I use the #111 coupler up front, with another MPJet clevis, for adjustability.

Really though, retro-fitting this to a built fuse is difficult at best to get bonded in properly.
You might include the pustrod install to the fuse build next time before either the top or bottom sheeting go on.

I buy my CF from

www.goodwindskites.com

Good luck, Target

PS. The fuses that I'm running these in are 58-60" long, and the planes fly in excess of 100MPH, no problems! Good enough for the Spirit, me thinks!

[TIA]

Good deal!

Thanks for all the great info guys.

I think I have a good idea of what I'm going to do now.

Thanks again! :)

[LVsoaring]

Hey Target, where do you get the MP Jet clevises? I googled it, looks like they come from the Czech Republic. Who carries them in the US?

[dwells]

Great looking Spirit there TIA, I fly one myself. If you don't have the push rod tubes intalled at this point, it would be difficult to get them mounted securely. The supplied push rods work just fine and are actually bass I believe and not balsa. I did replace the bass wood with aluminum tubing though which turned out to be just a bit lighter.

[TIA]

Hi.

Thanks for the complement. I feel I'm going to have to go with the basswood and wire for the rudder due to the design of the fuse, (going out the top), but do you think I can run a snake out the back of the fuse to connect right up to the elevator? It looks to me like the alignment is ok.

Any tips on where this thing likes to fly cg-wise?

Lastly, there's no towhook for this plane but I do have the three blind nuts mounted. Should I just bend a 4-40 rod and call it a day?

Thanks! :)

[dwells]

TIA,

The elevator rod indeed goes straight out of the end of the fuse and you can easily drop the wire through the fuse formers. If I were you I would use the supplied stuff. I fly the CG exactly on the rear edge of the spar...flies great. Whatever you can do for the tow hook will work, just needs to be smooth for release. Start with the front blind nut for sure.

Don