Ok here is the deal. I have an homemade foamie that I fly hard 3D with a 12X6 prop. When ever I do rolling circles the motor rips off of the front of the plane[X(]. So my question is how much will my torque reduce if I stick on a 12X3.8?

Thanks,
Kevin

post some pics of how you attach your motor to the fuse

If I could tell you that would be eaiser. It is a firewall outrunner motor mount glued to the front of the plane, in other words foam.

Kevin

I had problems with my motor ripping off, i used triangles of depron to support the firewall. I'll try to get a pic up tomorrow. This made it very strong. I've had pretty hard prop strikes that broke the prop and the motor stayed on.

Epoxy it on. It'll be on for good.

The only problem is that the foam breaks around the epoxy.

Kevin

Alright, new idea what if I use a stick mount? How long would it have to be to keep it from torqueing off? BTW this motor is extremely strong for a foamy 200 watts so I will have to have alot of holding power.

Kevin

Sorry for not getting a pic up today. A much lighter and stronger solution is triangular pieces glued with foam safe CA around the motor mount on all four sides. Not only will the foam break around the epoxy, it is much heavier. Bracing it with depron did the trick for me! I have another busy day tomorrow but I'll try to remember to post a pic.

God Bless!

Jay

Here's a pic. This is a plane I designed and I have a 12x4.7 on it. In this pic the prop is broken, still waiting for the order. This last flight I smashed it into the ground during a rolling harrier. It broke the prop, snapped off the upper depron in front of the motor, and cracked the wing about half way through. It was the third big crash I've had and only had to glue the firewall back on after the first crash. This mod adds a lot of strength without a lot of weight.

Ok thanks.

Kevin

I'd strongly suggest epoxy. It's much stronger than just CA, and is less brittle too. I've used it on about 15 foamies, and even in crashes have never lost one yet.

No matter what glue you use, you are still only gluing to foam.
Replace the foam triangles that you have behind the firewall with balsa.
This will give you wood glued to wood,,,,,,,,problem solved.

Exactly and that what I needed to fix. I think that I found the solution to my problem. If you look at the airfoilz planes mount's it will show you what I think that I will model mine after. Thank you all for your help and I will let you know how it turns out.

Kevin

do slower rolling circles=problem solved

LOL....... but where is the fun in that!

Kevin

Exactly,,,,,,,,,, don’t compromise on the maneuver,,,,,,,, fix the build problem.

Needs to be braced up with balsa as Piroflip says. It's not a torque problem, it's gyroscopic forces ripping the motor mount out. Try this, hold the plane with the nose pointed up. Now, put it at wide open throttle and swing the tail back and forth fairly fast like a pendulum. and feel the forces that are working against it swinging. That force is being put on your firewall and the glue is the only thing holding it. You need to transfer that load back to the sides of the fuselage with bracing.

Exactly like the Airfoilz planes. I believe that is what I will do. Now the big question lite ply or balsa supports?

Thanks,
Kevin

Light ply isn't much stronger than hard balsa, Kevin . Aircraft or birtch ply is much stronger. 3/32 would do the job. If you can slot it back into the foam to cover more area it will spread out the load. If it's a profile fuse you can glue 1/32 ply to the fuse sides and go back a few ins. and tie the firewall to that. there again, it spreads out the load. Let us know how it works out. I make some motor mounts from kitchen cutting board you can buy at Home Depot. It's about 1/2 in. thick but cuts like butter with a bandsaw. Very tough stuff.

i use balsa triangle stock to reinforce the motor mount area on my foamys

one question though?

how big of a foamy are you flying that your power system requires an 12/6 prop?
i have an 45" wingspan flat foamy that i fly with an 10/3.8 slowfly prop
it has plenty of power with this setup
seems like if you have a 33-35 inch wingspan flat foamy
and your power set requires that much prop
you could benefit more from an lighter power set
you will give up some of the punch on your veriticles, but
with less weight you will find that it flys better