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Some basic Half-A gear (above left). At the top is the Fora 049, a very competitive engine like the Profi 049. Below on the left is a 128 tpi custom needle valve from Texas Timers and Cox reed valve backplates with a 128 tpi needle for bladder feed from coxengines.ca. Next is a Norvel 061 with a wide open venturi and fine thread needle valve, followed by a stock Norvel 061 with its standard venturi and needle valve. Not shown since Phil didn't have one is the TeeDee/Medallion shaft valve engine which has a sturdier venturi than the


pressing the NV body in using the drill press. It goes in from the needle side. The fuel nip- ple has a stop machined onto it so the NV body can’t press in that way. It should take a firm press, maybe 3–5 pounds of pull. If it still won’t go in run the drill through the hole a couple of times to open it up slightly and try again. If it doesn’t seem to be working, go to a #32 drill (.116-inch). Try inserting the NV body into the hole with the drill press. See how tight it is. The press fit should be tight enough to be at worst very difficult to press out with a bare finger. Once you’re happy you can make the right


TeeDee. Cox 128 tpi needle valve assembly from Texas Timers (above right) fitted to a Norvel 061 with a wide open venturi by Roy Glenn. This motor had been fitted with a larger diameter needle valve used in some NV engines. Roy machined two small eyelets to press into the case and sized the inside diameter for a press fit on the needle valve. The needle was cut down and a knurled brass disk soldered on. The needle is held in place with a short piece of silicon tubing that provides drag on the needle and seals any air leaks.


size hole, try it on the right side of the case (looking from the rear). The hole should be a little off center, towards the crank, to leave as much material as possible. Try pressing the NV body part way in using the drill press. If it is difficult to pull out the hole is about the right size. Drill the other side out from the left. Then press the NV body in from the right until it hits the stop ring. Next cut down the needle. Get a small gear or a nut and drill it to fit snugly on the needle. Solder it in place on the needle so it is about ¹⁄₄ inch from the case. Then cut off the excess. Next it needs a seal. Get some


silicone or neoprene fuel tubing about ³⁄₃₂- inch inside diameter and cut off a piece about ¹⁄₄ inch long. The best way to do this is put a piece of ³⁄₃₂-inch wire in a piece of tub- ing and cut it to length by rolling a sharp knife on it to get a square smooth edge. Slide the tubing onto the needle and thread it into the NV body. The tubing will slide over the protuding part of the NV body and the needle threads and press on the nut or gear. The tubing should be tight enough to hold the needle from turning. Final step is to try things out on a plane. Boy do I go on! Until next time.


Combat Sources Texastimers.com


Freeflight stuff, timers, antiques, needle valves and other accessories


Coxengines.ca


Many original and new parts for the old Cox engines, including needle valves


www.foamwingcutting.com


Cutting foam wings for C/L and R/C video


http://home.earthlinkl.net/~philcartier


Phil believes Wayne McDaniel’s plane is on the left. These little high performance Half-As pretty much fly just like the larger F2D and Fast planes. The actual airspeeds are lower, but the turns, chasing, and excitement are just as great.


FLYING MODELS


Ready to use white foam wing panels for many popular models


47


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