This can't be true...
05-18-2003, 02:18 AM
#1
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This can't be true...
A wooden engine mount? I've never seen one before on a .25 sized plane. I building and old kit(maybe 10 years) of an RV-3 by Kyosho. They tell you to glue some ply together and mount the engine! Should I just buy a real mount or is this done for a reason?
05-18-2003, 03:25 AM
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Goldberg uses a wooden mount in their Eagle II trainer and that plane has been around for years, one of the best. Nothing wrong with 'em
Steve
Steve
05-18-2003, 05:30 AM
#5
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If you opt to use the wood mounts be sure to seal them really good before mounting and running the engine. If not before long you'll find a soggy mount and a vibrating engine.
If you use a "store bought" mount you will probably have to beef up the firewall somewhat. Either way make sure you have a good solid mount for your engine.
If you use a "store bought" mount you will probably have to beef up the firewall somewhat. Either way make sure you have a good solid mount for your engine.
05-18-2003, 02:13 PM
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Wooden engine mount
Wooden engine mounts were very typical about 20 years ago even for some pattern planes. The breakthrough was the introduction of fiber-filled molded mounts.
The problem I had with wooden engine mounts was that they would usually become 'crushed' by my tightening the mounting bolts every so often (blind nuts were under the wooden engine mounts). Not a big deal because my planes only lasted a short while but it was a problem as I became a better pilot and kept my planes longer.
And the caution above to keep the engine mount area fuelproofed is excellent. Fuel will eventually get into ANY exposed wood in the engine compartment. So I would accurately drill out the engine holes, then drill them out a little oversize, then coat the inside of the holes and the entire engine compartment with two hour epoxy, let it harden completely then drill out the engine holes again to the correct size. That coated the inside of the engine holes with fuel proof epoxy. But that was all eliminated when I changed to the fiber-filled molded engine mounts.
The problem I had with wooden engine mounts was that they would usually become 'crushed' by my tightening the mounting bolts every so often (blind nuts were under the wooden engine mounts). Not a big deal because my planes only lasted a short while but it was a problem as I became a better pilot and kept my planes longer.
And the caution above to keep the engine mount area fuelproofed is excellent. Fuel will eventually get into ANY exposed wood in the engine compartment. So I would accurately drill out the engine holes, then drill them out a little oversize, then coat the inside of the holes and the entire engine compartment with two hour epoxy, let it harden completely then drill out the engine holes again to the correct size. That coated the inside of the engine holes with fuel proof epoxy. But that was all eliminated when I changed to the fiber-filled molded engine mounts.
05-18-2003, 08:27 PM
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Wood mounts were good when they were made from Rock Maple. Now they're made from Beech or something that crushes more easily. The main problem with wood mounts is that they can make the tank compartment very small and they tend to be heavy. But they are very trustworthy. If the design calls for them I would generally have no qualms with using wood mounts.
05-19-2003, 01:45 AM
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Wood mounts are still commonly used in very competitive C/L stunt planes. Often, however, aluminum or glass-filled pads are used between the engine and the bearers to prevent crushing the wood. The pads are not difficult to make, but it may require you to do some modifications in order to keep the engine thrust line where you want it. 
Good luck, Dzl
Good luck, Dzl
05-20-2003, 01:11 PM
#13
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I still build some aircraft with Wood engine mounts. Most of the time the wood beams have some good aircraft ply for the actual engine mount. One thing that is a must is to seal the wood as others have said. I use thinned epoxy and have never had a problem.
Old Goldberg kits would bolt the plywood engine mount to the side wood beams this method worked well.
Old Goldberg kits would bolt the plywood engine mount to the side wood beams this method worked well.
05-20-2003, 05:33 PM
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wooden mounts have been around as long as the planes, my dad's carl goldberg sky tiger 20+ years old uses a .40 size engine i believe and it has a wooden mount, that im going to have to repair after having to rip the screws out of it to get the motor off
05-22-2003, 02:11 PM
#18
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I have used wood mounts. As stated, if you do it, build a couple extras at the same time so you can replace it if needed, seal them really well and check them often. I personally won't use them again, but that is just me. There is nothing wrong with them and it worked well. I just felt that it got weaker as it got soaked. I had it sealed, but it still soaked in the cracks. Check it to make sure it is good before you start it and you will be fine.
