stunthanger.com
Building Tips and technical articles. => 1/2 A building. => Topic started by: ray copeland on January 29, 2014, 08:54:08 PM
-
Anyone out there running a Norvel with crankcase pressure using the Norvel screw in backplate with a pressure tap? I have 5 1/2a's on the table right now ,1 will run a bladder, 1 a balloon tank and 3 will have hard tanks. I would like to try something other than muffler pressure on the hard tanks. The hole in the pressure backplate looks awful small but that may be what it takes, maybe need a one way valve?
-
Ray, from what I know of tapped backplates on Tee Dees, the hole is tiny. Some people fill a screw-in tap with JB Weld and a strand of copper from a 14ga wire through it(I'll double check on that size). After the JB sets, pull the wire out and there's your tap. I'm pretty sure Jim Thomerson says he uses a check valve in between. Fit90 from RCGroups is an expert on 1/2A pressure systems. I think one of the little plastic Fourmost valves is good if you can still get them. If you need one, I have a Fourmost and a couple of metal ones who's brand I forget. I don't need them, so let me know if you do.
Rusty
P.S. The Skyray is still flying. Never landed unintentionally. I'm presently copying it with new wood.
-
Ray, I have some experience with running them on pressure. As it was shown to me, the hole required has to be incredibly small. The fellow who set these up for me explained how he blackened the smallest music wire he had over a candle. He used small copper tubing fitted to the backplate with JB weld and he would solder the inside of the tubing and insert the blackened pin into the solder. This left an extremely small hole. As he suggested, the engine will run fine on the stock needle valve. The stock needle valve will not work properly on bladder. The smaller the hole the better and no back check valve is required. The engine is running on a 1/2A proto plane. I'm having difficulty though with the tank. It needs a little redesign. Ken
-
I take a piece of aluminum tube and crimp it hard over some .006 diameter wire. Pull the wire out and you have the proper size hole.
I have a reel of the wire and can send a length to any who want to try this technique. H^^
-
Thanks guys, i have a couple of the factory pressure backplates. I tried once a long time ago but i believe i drilled the hole larger,didn't work too well. I will give it a go with the standard hole once the weather breaks and give a shout back how it worked.