TS Carbon Paddles (these 20gram finished units are manufactured from broken TT CF blade sets)
Flying Results:
Expect a slightly higher cyclic rate as compared to the Miniature Aircraft 20 gram 3-D paddles with similar hovering stability which the stock TT paddles enjoy. Typical 600mm rotor disk pitching in fast forward flight is lower and the onset is notably milder. Flybar weight is needed to fine tune the system for fast flying. We basically ended up with a faster maximum cyclic rate while enjoying an expo like feel or heavy paddle like feel in the hover.
1) Cut the paddles from the blade section using a miter box. The paddle chord is 55mm and the span is 100mm. The fitting hole is centered spanwise at 20mm from the inboard end. You might want the TT logo facing up or down when installed on the helicopter rotor head so decide before drilling the paddle for the threaded metal fitting .
2) Drill 1/16 inch pilot holes at approximately ¼ chord or centered 17mm back from the leading edge. Make sure the paddle incidence is 90 degrees to the drill bit.
3) Lay second paddle over the first to jig drill. Make sure the paddle incidence is 90 degrees to the drill bit. Make sure the overlaid paddle incidence is 90 degrees to the drill bit.
4) Find a muffler stand off/support or some round aluminum stock and drill 90 degrees at half the length on two short pieces. Use a #41 drill for the 3mm tap you’ll use to thread the hole. What you decide to use for metal stock depends on what is laying around the work shop.
5) Gradually make the hole in the paddle the same as the aluminum stock outside diameter. Do so by changing drill bits several times.
6) Lay the paddles on top of each other with a long piece of round stock shoved through both to check that they are drilled the same.
7) If they are not the same elongate the big paddle holes in opposite directions so that they are.
8) Dig out the foam core to a depth just before the round paddle hole, but not into it.
9) File threaded round stock ends to the correct chord height making sure they are symmetrical and even to the 3mm threaded hole.
10) Poke the flybar through the thin section of remaining foam and into the cavity center you drilled in the paddle.
11) Epoxy glue the aluminum fittings into the paddles and align with the flybar threaded in. Align 90 degrees to the chord and center to the span and chord height. Repeat this process with the other paddle. Use car wax on the flybar in case epoxy comes in contact. 5-minute epoxy works well since you can align and wait for it to harden.
12) Finally remove the flybar and clean and recoat with car wax. Thread into the paddle again and pour 5 minute epoxy into the paddle cavity you dug the foam from. The glue will run in and level itself with the paddle inboard end up. At this time you must make sure the flybar is installed straight to the paddle length and span wise. Let harden and thread out the flybar. Then do the next paddle.
13) Take some filings or drill swarf from drilling the carbon blades and mix with epoxy then apply it to the outside paddle edge. Let harden, sand lightly and finally coat with CA. The CA turns the gray ends black. You can do the same with the inboard ends if you like.
14) The paddles should either be installed with loctite into the metal fittings or by another secure manner, but the wax has to be removed from the flybar, epoxy thread bore and fitting. You’ll find the epoxy formed threads in the paddle inboard end to be fairly good for CA application, if you want to employ this bonding agent the keep the paddles aligned. Just wick thin CA in carefully. I used acetone on a twisted paper towel to clean the waxy internals prior to glue application. If this does not hold well enough then you can apply CA through holes drilled in the ends of the paddle fittings or carefully use jam nuts with washers snugged up against the paddle inboard end.
The wax is used as a release compound. The metal fittings ensure the paddles cannot depart the flybar even if the epoxy thread let go. JB weld might hold the paddle on but we are not sure since it may not bond correctly to the carbon paddle structure. Go for the threaded metal inserts (just like the R-60) above to be safe. Test torque the paddles after everything is cured to make sure they cannot shift incidence.
Finally if it does not work out for you, I’m not at fault. This type of manufacturing is carried out solely and entirely at the risk of the builder. The paddle system should be pre-stressed before flight. I’m sure there are other ways to safely build these paddles so feel free to modify the process. The paddles have low centrifugal loads compared to the main rotor blades, so don’t over build either, it isn’t a tractor.
