Profile Engine Mount question?

I have a question on how to bolt on a engine mount plate.
Do you use wood screws or 4-40 bolts?
I had already planned on using 4-40 cap screw with blind nuts to bolt the engine to the plane and just drilling holes in the plate. But to attach the plate I see 4 what seems to be screws on the plate.

Help please. ( a picture is worth 1000 words)

Thanks
Paul

I've never seen a plate that big under an engine. Seems like it would be heavy.

It's not mine. Someone posted it here awhile back.

I have a plastic one from Brodak. No instructions on how to mount it.

Thanks
Paul

>It's not mine. Someone posted it here awhile back.
>
>I have a plastic one from Brodak. No instructions on how to
>mount it.

I love those Brodak plastic profile mounts! I've even constructed a template to use with my router so I can effectively "inlay" the Brodak mount so it is flush with the ply doublers. You can just stack it on top of the ply doubler but that seems to add more assymetry to the model centerline and the motor center line (you get the thrust line too far outboard for my tastes).

I've gotten some amazingly solid profile motor runs on my last several ships.

>I have a question on how to bolt on a engine mount plate.
>Do you use wood screws or 4-40 bolts?
>I had already planned on using 4-40 cap screw with blind
>nuts to bolt the engine to the plane and just drilling holes
>in the plate. But to attach the plate I see 4 what seems to
>be screws on the plate.
>
>Help please. ( a picture is worth 1000 words)
>

My personal preference is *never* to use wood screws. The oil gets into the wood, softens it, and the screws pull out. I *always* bolt through and use either blind nuts or nylock nuts. I really prefer the nylocks, which have nylon inserts that prevent the nuts from vibrating loose. So I would advise you to bolt the plate on using socket head screws passing through the fuselage, and secured with nylock nuts. If the protruding nuts really offend you, use blind nuts, but they can pull out and damage your finish over time. I prefer the nylocks. If you want to further improve things, line the holes through the fusleage with bushings made of brass tubing. These can be held in place with thin CA. This virtually eliminates oil penetration, and prevents the wood from being crushed when the bolts are tightened. This minimizes damage from vibration, which also tends to crush the wood.

Just drill the Brodak plastic plate the same as your engine and bolt through everything using blind nuts or lock nuts. The reason the aluminum plates use 8 screws is so engines can changed without needing to re-drill the airplane.

http://www.clstunt.com/htdocs/dcforum/DCForumID1/9659.html
Never use wood screws, Bolts only with nyloc nuts.

Hey Paul,

Hey you guys!!! That's my plane/picture! You are correct that small wood screws are used to hold the mounting plate in place. But they are not used for mounting the engine. The main engine mounting screws are 4-40 allen screws which go through holes in the plate and the fuselage into blind nuts. The front two wood screws are located such that they go into the engine mounting blocks beneath the plywood doublers. The other two go into the plywood doubler. Never had a problem with them stripping out.

I cut the plates out of 1/16th hard aluminum plate most of the time. I have used thinner stuff, but it scrunches down and really offers no real advantage to just mounting directly to the wood.

As far as weight goes, the plate in the picture above weighs just about 13 grams. That's less than a half ounce. That's less than most most tongue mufflers. It's also less than the small veco wheel in the picture below. I like the protection this kind of mount provides to the wood. Polish them up and it looks good and makes a very solid mount.

To each his/her own. But for me it's the only way to go on a profile.

John,

I LIKE your engine mount. After I saw it in the earlier post, I based the front end of my Buster on it. Now the Buster isn't done yet (sorry Paul) but fuselage with the inlet metal mount is all together and glassed. Anyone can make a light airplane that starts to self destruct before you get it trimmed out. It is a lot harder to make a light-enough airplane that you can fly a few years....

Thanks for posting YOUR solution.

Dave
LA_Flyer

SIG Buster Preassembly Photo

Hello Dave,

Your motor mount is terrific!! You took it a couple of steps farther than I did. A couple of the guys in our club here said the same thing...that's got to be heavy, until I tell them it weighs less than half an ounce. I build pretty light most of the time and an extra half ounce spread out over the nose is usually insignificant.

Looks like yours is thicker material that will be inset into the fuselage. I've thought of doing it that way, but haven't got around to trying it yet. I use a scroll saw to cut mine out. Then use a file to finish the shape out. Usually wears the blade out to do just one; but the blades are pretty cheap. That's a trick way to get a solid front end the way you make the custom hard wood piece. Ought to make for a very stiff front end.

Another Way

Engine plates recessed.

Thanks guys for the advice. This helps.
The photo's are great. You guys are craftsman!

Now have have another little problem. (see warp post)

Paul