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Building Tips and technical articles. => Building techniques => Topic started by: t michael jennings on May 14, 2014, 07:34:56 PM
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Gentlemen,
Considering using a Glass Filled Engine Mount for my next aircraft. The engine is to be mounted horizontal (like a profile) rather than inverted.
Have several questions about using Glass Filled Engine Mount.
1) Do you drill and tap the Mount to hold the engine mounting bolts?
2) If not, how do you hold the engine to the Mount?
Plan to use 2 degree engine offset.
3) Do you sand 2 degree wedge in the back side of the mount?
4) Do you use the 2 degree plastic wedges on the back side of the mount?
5) Do you angle the F1 former at a 2 degree offset?
Most F1 former design for Glass Filled Engine Mounts are 1/4 inch (two 1/8 ply epoxied together) thick.
6) What additional design changes need to be done to strengthen the nose of the aircraft?
A design using an Engine Mount rather than the 1/2 X 3/4 Hard Maple Beams is Tom Dixon's THUNDERBIRD 60 Mk II.
Tom's design only states "2 degree Right Thrust." Not how to get the offset. The F1 former is 1/4 inch Violett Carbon/Bal Laminate, but it is not clear how the laminate fastened to the fuselage.
7) Is there a recommended design for using a Glass Filled Engine Mount?
8) Overall, is going the Glass Filled Engine Mount a better idea than the Maple Beam mount? (weight, simplicity, strength, etc...)
Thanks for your assistance.
T Michael Jennings ???
Knoxville, TN.
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Gentlemen,
Considering using a Glass Filled Engine Mount for my next aircraft. The engine is to be mounted horizontal (like a profile) rather than inverted.
Have several questions about using Glass Filled Engine Mount.
1) Do you drill and tap the Mount to hold the engine mounting bolts?
2) If not, how do you hold the engine to the Mount?
Plan to use 2 degree engine offset.
3) Do you sand 2 degree wedge in the back side of the mount?
4) Do you use the 2 degree plastic wedges on the back side of the mount?
5) Do you angle the F1 former at a 2 degree offset?
Most F1 former design for Glass Filled Engine Mounts are 1/4 inch (two 1/8 ply epoxied together) thick.
6) What additional design changes need to be done to strengthen the nose of the aircraft?
A design using an Engine Mount rather than the 1/2 X 3/4 Hard Maple Beams is Tom Dixon's THUNDERBIRD 60 Mk II.
Tom's design only states "2 degree Right Thrust." Not how to get the offset. The F1 former is 1/4 inch Violett Carbon/Bal Laminate, but it is not clear how the laminate fastened to the fuselage.
7) Is there a recommended design for using a Glass Filled Engine Mount?
8) Overall, is going the Glass Filled Engine Mount a better idea than the Maple Beam mount? (weight, simplicity, strength, etc...)
I would recommend checking out the Imitation plans, they seem to most of your questions, particularly #7.
Brett
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All I'm going to say is I drill and tap the composite mounts like the aluminum ones.
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The basic problem is that firewalls are tougher to fasten to the nose of the plane than beam mounts onto plywood nose doublers. Looks to me like a job for quite a few layers of fiberglass cloth, or a single layer of really heavy FG cloth, like 8 oz, with epoxy. It's tough to get it to bend around the corners, but there are ways to make it happen. The next problem is having tank access. Through the firewall makes sense to me, but opinions will vary. H^^ Steve
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Brett,
John,
Steve,
Charles,
Thanks for the info and advice.
Michael
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The basic problem is that firewalls are tougher to fasten to the nose of the plane than beam mounts onto plywood nose doublers. Looks to me like a job for quite a few layers of fiberglass cloth, or a single layer of really heavy FG cloth, like 8 oz, with epoxy.
I have helped a few guys get their RC ARFs assembled and functional, and I have found that hardwood triangle stock, epoxied over the firewall/fuse side doubler joint, does wonders for the durability, and in some case, the engines picked up alarming amounts of power, like 1000-1500 RPM.
Brett
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Brett is right on with the triangle stock comment. I am flying my 6th and 7th airplanes with this type of mount with no problems at all by using triangle stock to build the "box' front end for the radial mounts. My Crosswind #1 has over a thousand flights on it with a PA65.