Flight Streak ARF fix?

Is there a easy fix for the very soft engine mounts in the Top Flight ARF Flight Streak?

Yes, used ALU pads on both sides of the mounts.

As circle burner says, Aluminum pads under the motor mount lugs and the mount nuts on the other side. They should be 0.064 (1/16th inch) thick and extend fowrard and aft of the motor beams about 1/4th inch and 1/16th inch out wider than the motor beams. On the nut side, they can be a little smaller, but not by much. The idea here is to distribute the load out over a wider ares so the mount lugs and nuts don't sink into the wood.

Mine are bigger than this and the wood still wants to crush, have to be careful not to tighten too much. I'm using locking nuts with the plastic inserts plus lock washers on the screw heads. Inserting copper/brass tubing through the mm beams as suggested here would harden the mounting point, then use the aluminum pads if you are still concerned (overkill probably but what the heck).

No offense intended, but it is stunning to see how many times this has been addressed by myself, plus the input of others, and we still get questions.

The wood will crush no matter how much the load is spread over more area. What you really need is a way to prevent this compression.

Drill fuselage to match engine lugs. Drill these holes to 1/4". Epoxy short lengths of 1/4" dowel into holes. Let dry. Trim flush. Drill again to mount engine.

It is still a good idea to use hardened aluminum pads under engine lugs. Similar pads on left side of fuselage also a good idea if using lock nuts instead of blind nuts.

Unless using a Fox 35 there is no crying need to tighten engine mounting bolts to the point where stock motor mount sticks are squished.

>No offense intended, but it is stunning to see how many
>times this has been addressed by myself, plus the input of
>others, and we still get questions.
>
>The wood will crush no matter how much the load is spread
>over more area. What you really need is a way to prevent
>this compression.
>
>Drill fuselage to match engine lugs. Drill these holes to
>1/4". Epoxy short lengths of 1/4" dowel into holes. Let dry.
>Trim flush. Drill again to mount engine.
>
>It is still a good idea to use hardened aluminum pads under
>engine lugs. Similar pads on left side of fuselage also a
>good idea if using lock nuts instead of blind nuts.
>
>Unless using a Fox 35 there is no crying need to tighten
>engine mounting bolts to the point where stock motor mount
>sticks are squished.
>
>Dan
>
Thanks to all...

Here's the history: engine is a TT .25 installed originally per plans but with very large washers on the back. first flight wallowed the holes out. removed engine drilled out the holes and epoxied in 1/4in dowel, redrilld holes. lasted a couple of flights. Maybe I had contamination in the wood before the epoxy trick (should have done it from the beginning)now the aluminum strips on the back are digging into the soft under material and the dowels are pulling free tearing out some of the soft engine mount.

I'll do a better job on the next one.

Ron,

I wouldn't give up on it.

That soft wood, especially if it has been damaged, might be easy to remove. Plus if you poke around a little you will see that top and bottom fuselage pieces, those between doublers and triplers, are considerably less than full depth.

So it is quite likely possible to cut perimeters of fuselage away, gaining further access to stock motor mount sticks.

Granted, slipping in full-length maple mounts of the sort we like to use when building a new model is not too likely, even if it is possible as you will see if you really dig into this oil-soaked wretch.

Whatever you end up with, sheeting it all over with high-quality plywood will surely result in a stronger-than-new model.

I'd posted this before but the easiest way to prevent this is to drill and install brass tubing in the mounting holes.Pass your bolts through these and with washers on the otherend you won't have any compression problems. I have over 60 flights on my first Streak with no problems. Power is an OS20fp, 9-4 APC.
Dennis

How about the brass threaded inserts that Du Bro makes being installed through the mounts, then mount the engine on them???

>
> How about the brass threaded inserts that Du Bro makes
>being installed through the mounts, then mount the engine on
>them???
>

I don't think that you have enough 'meat' there to do that. Even the du bro inserts as small as that are still need an 11/32 hole to install.
Dennis