here are three way that I can mount this engine there is a 2 1/4 inch space beetween the fire wall and the engine plane hanger 9 edge 540 33%

Ronman
The stand off's will work here is a pic of how mine is mounted on
my DR Hobbies 2.6 Also go to the link click on kit photo and there are more pic's at the
bottom of the page
http://bpassociates.homestead.com/ExtraRep.html

My choice would be pic 1, then 3. I'm not fond #2. My only concern with #1 is the firewall eventually compressing a bit under the concentrated load of the standoff.

-Ben

Ben Biss
why aren't you fond with 2 ? Thats the one I am seriously considuring.
Todd Bloss what about the manual it does not recomend that typpe of setup ?

I personnally use #1.
The most stable is number 3.
THe wood comprising the firewall will compress using #1 & #2.
Setup #3 will prevent that as well as reduce the chance that the engine mount will break.

The stand off's will work if you have aluminum stand off's and the aluminum plate for the stand off's to sit
on, this keeps the firewall from compressing. The problem that I have had using wood spacers
is the wood will compress and the bolts will loosen up. When you tighten them up
you can change the thrust in the motor. I have shown Keith the set up on my plane
and he liked it because there is no way you can warp the motor mount because of the
plate on the firewall. ( one other Pic I forgot this keeps the firewall from compressing)
Hope this helps

What thickness is the aluminum plate.
Do you mount one on both sides of the firewall?

They are 1/4 plates, if you have the 3in hole in all plates the whole mount weights 9oz

Ron- Regarding #2, I'm concerned about the small amount of wood supporting the very high compressive load.

Toddbloss: the probleme with nuber one is that I don't have a plate to put beetween the engine mount and the stand off.
number 3 do you think the bolts will loosen up the same on number 3 ?

This is the set up I have on mine and it has not come loose yet. Maybe I should check it, but it has worked for me so far.

I guarantee you Todd's would be better, I don't think it will be lighter though.

RTK,
you are right mine is heavier, It does make it a little easier to balance the plane.
On the mount like yours I would always check the bolts and they would seem lose,
so I would tighten them and in return it was compressing the wood cauding the
thrust to change.

Todd, I am going to give your method a try as soon as I convert over to li-ion batteries from NiMh.
I guess I might not be checking my mount often enough.

Sounds good, I have had good luck with the mount.
If the plane you have is the Comp-Arf you will need
2 - 1/4in plates and the spacers will also need to be 1/4in

Here's the mount I made for my BME 105. It sets the motor out about 2" and fills Keith's bill for support around the entire circumference of the radial engine mount. It's seen hundreds of flights and this year will be its third year of duty mostly behind a BME 110. It's light, builds quick, and I can say that I've not experienced any compression of the wood in the motor mount and resulting loosening of the bolts. Many ways to skin a cat, for sure, this has proved absolutely trouble free for me.

Tim_Indy
The solution is pretty neat!


Is there any reason (more distance away from the firewall allowing better cooling...) against mounting the engine directly on the firewall as oppose to using standoffs?

Albatross, the only reason I didn't mount directly to the firewall was I needed to set the engine out 2 inches for the spinner to properly mate with the cowling. I originally had a Great Planes 330L kit and simply built the motor box long enough to mount the engine directly on the firewall. Engone cooling was never an issue.