Eflite Pitts 12 15e conversion to 4stroke glow - RC Groups
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Mar 19, 2012, 11:50 PM
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Build Log

Eflite Pitts 12 15e conversion to 4stroke glow

Here she is as she sat when I got her.

Tear down


See the broken spar in there

Also broken firewall

This is the prop. 11x6, should let me run this engine at a good speed.

Fuel proofed the firewall, bay cover, and inside the fuse

Battery I will use. Hopefully this will help balance the CG

This is where it is on the plane, but it will be inside for sure.

Snug fit for sure. I will likely have to cut out the area of the cowl around the head to keep it from melting onto the engine.

This picture shows that the carb will have to be inside the fuse so the firewall will have to be cut away for that.

Overall engine placement

This shows what the front will look like when mounted.

Fuel tank will go here, it will be pressurized, and foam mounted.

Couple notes:

I will mount the engine right side up so the exhaust can be directed down, and so the choke pull as well as the mixture screw can be extended out the sides of the fuselage for easy adjustment.
I will be making a solid firewall from 1/8th inch basswood, that will be screwed and epoxied to the current firewall.
I will be using a vibration absorbing mount that has rubber bushings to keep from shaking this thing to death.
I have to use the 11x6 prop because the 12x6 only turns 9700 rpm on this engine and that isnt enough to run in the sweet spot.
I will have to bend the exhaust pipe to a 45* angle so it doesnt interfere with the firewall, unless I get a 90* manifold and a straight head pipe(Anyone know where to get this?)
I will be using basswood dowls to make supports inside the fuselage once its all together, this thumper will vibrate alot more than that electric motor did.
I am mounting the fuel tank under that support, because after it runs and flies I will be installing a smoke system, and the tank for that will mount on top of the battery tray.
I am searching for a figurine to install inside the canopy, but as of yet I havnt found what Im looking for.
I will be using a Spektrum DX7s to fly it.
I have named the plane "Confutetion" because everyone I have spoken with said it couldnt be done. Confute means to prove a person or an assertion wrong. I think it fits.
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Mar 20, 2012, 07:05 PM
If you want to continue with your folly, here are my recommendations. Do not use basswood sheet for the firewall, its too brittle. Use birch plywood, not lite-ply. Try to get at least a 1/4 inch or more total firewall thickness. If your going to use dowels to reinforce the fuselage, carry them from the firewall to the trail edge of the wing area. And I hope you did use epoxy for your fuel proofing efforts which will also reinforce the existing glue joints.
Mar 20, 2012, 08:20 PM
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Toysrme's Avatar
ya no kidding.
i built an ace bipe that size with an FS-26, much smaller & lighter than your 40. turns a 10*6 around 9000-9500rpm.
after much work it balances correctly, however it has a huge issue with torque rolling at low speeds and ground handling is absurd. if you breathe it will nose over.

jjkupinski is all over it.
toss the firewall. it needs to be aircraft ply (5 ply) not lite ply.
toss the low grade basswood for an actual hardwood worth something (birch, etc)
Mar 20, 2012, 09:29 PM
Registered User
Thanks for the input. I will make those changes. I did use epoxy for the fuelproofing. I was thinking the basswood would be ok since its going to be laminated to the existing structure. That will make it 1/4 inch thick, but if you guys think it needs to be birch I will do that instead.
Mar 20, 2012, 10:31 PM
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ckreef's Avatar
Nice build. Did you also post on RCU ??? Watching both threads.
Mar 21, 2012, 07:36 PM
team sleprock
whiskykid's Avatar
I like it FATBOY!

I also am gonna put a 4 stroker in an E-Flight plane,with the lack of any good nitro kits in this size! mine is gonna be a new extra 260 3d 480! should be here Fri.

I'm going with an original OS 20fs I've had nearly 20 yrs! still flys great! I have it in a 45" superfly right now!

keep up the good work on that pitts, should be fun!

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