Well, not so much a question as a request.

I'm in the process of building the Dynaflite Super Decathlon, and planning to put a Zenoah G-38 on it. I've read as many threads as I can find here on RCU, including the current build thread that's going [link=http://www.rcuniverse.com/forum/fb.asp?m=4082993]Building a Dynaflite Super Decathlon [/link] . But haven't found exactly what I'm looking for.

I'm close to finishing up the wing panels and will be starting the fuselage soon. I haven't been able to find any pictures of the Zenoah G-38 mounted on the plane. I'm going to use the Bisson Pitts muffler on the motor. When I look at the plans and do measuring of the cowl and engine area I'm not quite sure how to modify the mount to get this all in. I know that a lot of people here on RCU have the G-38 on this plane (in fact it was posts from lots of members that helped me decide to use the G-38).

If possible can I get some pictures of how everybody using the plane/motor combo have mounted it to the firewall? I'm especially interested in how the muffler fits because it mounts on the backside of the motor's head.

Huge thanks in advance for any help I can get on this.

Ken

Ken


I don't have a digital camera but I can try to explain what I did to mount mine (I mounted it last week). I followed steps 1 & 2 in the Gas Engine Installation section & laminated everything together. I then went to step 2 in the Glow Engine Install section & marked the firewall for where the centerline & thrust line should be located. I then extended these lines onto the lamintaed engine mount with the mount positioned over the firewall as shown in the picture above step 4 for glow engine installation. Next I took the measurements of the mount plate that comes with the G38 & centered it exactly over the centerlines of the laminated engine mount pieces. I marked the mount hole locations and drilled the out to accept 1/4 20 blind nuts that are 5/16" inch deep.

From here, I determined that to get the 6 7/8" required spacing from the firewall to the back of the spinner backplate, I needed spacers that were exactly 1 1/4" long. I made these spacers out of pieces of laminated 3/4" birch plywood & 1/2" solid pine (epoxied together). I traced a pattern onto the birch plywood that would match the contour of the G38 mount plate but not interfer with the allen head bolts that are used to mount the plate to the engine itself.

Once that was accomplished, I positioned the laminated engine mount (with the blind nuts installed) back over the firewall and drilled 4 holes through it & the firewall and installed 1/4 20 blind nuts onto the back of the firewall. Now to mount the engine, bolt the laminated engine mount to the firewall then bolt the engine to the laminated engine mount.

The only tricky part about this is the bolt for the upper right engine mount needs to be a different length than the rest so that it does not protrude into the area where you need to glue a 1/4 inch balsa stringer for the top sheeting. I used 2" bolts for the other 3 mounts & only 1 1/2" bolt for that mount.

I should also mention that you need to drill a hole through the engine mount right at the centerline so the shaft protruding from the back of the engine does not rub against the mount.

Mounting it this way, there is about 1/2" clearance from the muffler (stock) to the firewall. I will be getting a bennet smoke muffler & hopefully that will fit without the need to modify things further.

I installed my cowl tonite & you will need to cut an opening around the carb as it is too wide to fit concealed inside the cowl. Also, the ignition module buts right up to the lower inlet hole on the cowl, providing just enough clearance for the spinner back plate.



Hope this helps you out.


Jim

Wnuk,
Thanks for replying. Hopefully I can still get some pictures posted. I understand what you are saying, but I still have confusion for fitting the muffler in. Also, I guess I'm just a bit slow tonight (was a really long day at the flying field today!! Yippee) because I understand what you're saying, but just can't picture it completely. I guess that all comes in with the saying "a picture is worth a thousand words!!!". But trust me, I do appreciate everything you posted too.

Thanks

Ken

I know what you mean Ken, Pictures do provide a lot more. Sorry I can't provide them for you. Loooking at it, I really don't see the muffler being an issue but then again, I don't have the muffler I'm going to use with me either!

Hopefully someone will post some pics for you.


Jim

I used the Bennett cup mount, spring starter and muffler. It fits just right. I'm in final stages of covering etc. Still need to find a warm day to paint cowl.

Richard,
Do you have any pictures of your install??

Thanks in advance

Ken

It's not mounted right now, as windshield is clamped on fuse waiting for glue to dry. I don't have tail feathers mounted yet either. Hope to do that within a few days. I used the engine mount method shown on plans. However I did cut new firewall and mount parts with better aircraft ply.

Richard,
Where did you order that mount from??

Ken

Here is the link

http://www.bennettbuilt.com/

RCKen, some pics of my install.

Jim,
Thanks!!! That's exactly what I was looking for!!

Ken