What size engines fit identical mounts? (first flight question)

Ther is no chart but many of us will know what engines will drop in for most others. What engine does it currently have?

An Enya 15-IV (size 15).

---Matt

I would check the width of the engine lugs, and then check the 'net for specs on the engine you're going to replace it with. Most engine manufacturers have their manuals in dowloadable .pdf format. BTW, you may have to re-drill the mount because the holes may not be the same distance apart. As a second option, you might want to replace your old mount with one that'll fit your new engine!

Morris

Unfortunately, I can't. The old mount is a piece of 1/4" aircraft plywood sandwiched between the upper and lower halves of a Styrofoam fuselage. The fuse was glued together with epoxy, and the mount was epoxied in as well, on both sides. Removing the mount will necessitate destruction of the fuselage -- which will negate my need for a larger engine!

Wouldn't you be able to just dremal the cutout to a larger size if necessary, and drill new mounting holes?

David

It's one of the options I've been considering. The problem with it is that I can't get to the underside of the mount to install the new nuts without gouging some chunks out of the fuse.

ATC, I thought I'd try to find a larger engine that would fit the mount. Or, as a friend told me, just get a new plane! :)

As you've discovered, the venerable iron pistoned Enya .15 IV is a heavy and largish sized engine for capacity, and not particularly powerful for class. Add in its weighty muffler and there is a need to build light with a generous aerofoil section and wing loading for it will work well - in certain applications.

As for the mounting lug dimensions, whether deliberate or not Enya and O.S. invariably differ in both the lateral and longitudinal spacing of their mounting holes. The width I can understand as it's crankcase width related, but it is annoying that they'll differ by ½ to 1mm in their chosen fore-aft spacing apart. Just enough so it's either a force fit with undersize mounting bolts or won't fit at all. eg: Enya's 45CX vs O.S. 46SF, FX, AX. If it weren't for this, you could just widen the bearers which is easily enough done with many glass reinforced plastic mounts these days.

Most manufacturers today conform to O.S.'s spacing so they are drop in replacements for the world's most popular brand. eg: TT's Pro 46, Magnum's XLS52A which are drop ins for O.S's 46SF, FX & AX.

Just remove the Enya, drill out the existing holes with an oversize drill to expose fresh wood, add a drop of aliphatic resin and dowel the holes. Reface the bearer surface, seal and redrill for your new engine. Voila!

If its one of those glass filled mounts, drill and tap for the proper bolt. Do not tap all the way thru the mount and it will act like a lock nut. No nuts needed. Never had one so much as loosen although I DO use lock nuts on large (.60+) engines. I aint crazy!

Much better. You're not going to be able to simply punch up a chart listing the dimensions of every engine ever manufactured. You know anybody that would spend the countless hours required to compile that kind of information for no other reward than the "warm fuzzies" from helping out their fellow modelers? I don't. You think competing manufacturers are going cooperate in the name of making things easier for the average consumer? I don't.

Websites like Tower Hobbies list the engine dimensions for the engines they sell. That's as close as you're going to get.

I think that particular Enya shares the same crankcase with my Enya .19-IV, which fits in a Dave Brown 2025 engine mount. A Magnum .25XL or .28XL also fits in the same mount. I also believe the OS .25LA fits in that mount.

You could also gain a signifigant amount of power by going to a modern Schneurle ported .15 engine, like any that are currently on the market. What you have is an old baffle-piston, cross-scavenged engine that spits more fuel than it burns.

Thanks for the info. I appreciate it.

Sure do. The kind of people that create an excellent flight simulator and release it for free. Or that come up with a new secure crypto algorithm and then refuse to patent it. Or that work their tail off for 70-odd years, and then will all their savings to a nearby school. :)

Actually, I think the net is crowded with people that spend countless hours setting up sites that provide help and information to others - for example just look at all the guys who know lots about RC planes on this newsgroup who spend much of their time here answering questions for those of us that need and appreciate help

David

Matt Senecal wrote: