I would like to say that Cox engines aren't real sensitive to tank height but like any engine its really a matter of gravity. I would suggest though, especially if its an old tank to take it apart and check to see that the pickup is soldered securely to the tank. Pressurize the tank prior to use under water with caps on the vent pipes and pressurize it hard and look for bubbles. Not all pickups are truly centered within the tank. The center of crankshaft would be a good starting point. Keep your fuel line as short as possible as well if that means moving the tank forward. My concern is the Sure Start that you plan to use. The Clown is sensitive as is, using a Black Widow engine protrudes out considerably more than the product engine. I would suggest if the plane isn't already built to make another fuse extending the nose an inch. If its already to go heavier wheels would aid the balance but the wheels are somewhat close to the CG now. I have made brass spinners for some engines to help with tail heavy planes and of course you could always epoxy some 1/4 oz. weight to the side of the fuse up against the nylon mount. Props can help in addition to aid in balance for instance the APC props are slightly heavier than wood or Master Airscrew props. Sometimes I find it necessary to cap one of the vents leaving the other open to atmosphere which can stop siphoning, increase fuel draw, also assist you if the engine decides it wants to run backwards. You can easily place your finger over the open vent and it will shut the engine down for restart. I'm quite fond of the Cox engines and with the latest available hop ups you can really get a performer without breaking the bank. Bernie from Xenalook can provide higher performance cylinders, high compression plugs and better quality reeds available in a few flavors for you to try. The Killer Bee backplates once again are available complete with the true Killer Bee needle valve which is finer thread than the standard Sure Start. This also brings something to my mind. The Stock needle valve is too long if you decide to do away with the choke tube which you will need to do if using the Brodak mount. Therefore the needle is going to go all over the map if left long and vibration will actually make it unscrew itself. I generally cut them down about 5/8". Short needle valves are available for the Sure Start. You can also use the stock one like I do and hook a rubber band around it at the knob and proceed to wrap it around the fuse one to two times and rehook it on the needle. This will hold it steady and prevent it from turning at least until the rubber band gets gooey and disolves. Another suggestion would be to soak the holes in the fuse for the mounts with some thin ca. This will harden that area and prevent your mount from crushing the fuse. Ken
Topic: Tank mounting for baby clown (Read 904 times)
