paully_321

I bought a Ultra Sport 40 ARF kit on ebay. It'w really pretty sweet, But I have a problem...I mounted a OS 46 LA in and it's about 5/8" shot of the prop being able to clear the cowling. I mounted the engine well out on the mount (about 1/4" from the end).

Is there anything I can do to easily fix this? It is 4.75 inches from firewall to edge of cowling and the current engine mount is 3 inches.

I have included photos.

Any help is appreciated,

Paul

ChuckW

You might try making a plywood spacer for the engine mount and using longer screws. I've done this before although it has always just been for 1/4 inch or so.

Gray Beard

My Feedback: (-1)

Yep, you can make up A spacer from Ply, thickness as needed and use longer screws. You may have to carve on the cowl to make the engine clear the areas that were already cut for the last engine. CG will also probably change too. Or you may contact Tower and get another cowl and start from scratch. Just one of the little problems of swapping engines, both size and make. Looks like A nice plane, good luck!!

nedyob

My Feedback: (67)

Or try the next size bigger motor mount DuBro has, It sould have longer motor mount beams. Was your cowel pre cut for the engine already, or dod you do it your self??
NEDYOB

horace315

My Feedback: (15)

looks like you can either trim the cowl some or move it further back on the fuse?if not a spacer would do the trick like was said here.

TedMo

Best solution is to obtain longer mounts which are readily available. I assume you cut the hole in cowl for needle valve, too bad. other methods mentioned will also work but would require pretty thick ply shimming. Kind of strange that they provide such a short mount with arf?

Campy

My Feedback: (1)

Be careful with a mount with longer arms. SOME mounts, unless reenforced properly by the factory, can allow the engine to move.

I had this happen with a Saito 82. When I gave the engine a sudden burst of throttle the mount allowed the engine to move. I initially had 1/8" - 3/16" from the back edge of the prop to the cowl. During a bench run with the engine I heard a noise and killed the engine. The front of the cowl had been scraped by the prop. The paint was visible on the back edge of the prop as well as the faint cracks (plural). The prop was a brand new APC prop. Because I didn't think it was the mount, I put on another new prop and did the bench run again. The 2nd time the prop gouged the cowl and broke the prop blade. After removing the cowl and running the engine a 3rd time you could see the arc of the prop move AND the engine move when the throttle was suddenly advanced.

After repairing the cowl, I shimmed the shorter motor mount with some 5/8" ply and used longer bolts.

Not all longer mounts will flex, just a heads up.

paully_321

Okay,

So, let's say I use a piece of 5/8" ply...should I drill the holes into the same configuration and just bolt it as a shim or should I add some epoxy between the shim and the firewall?

I did cut that hole and they don't make that plane anymore...(F word here).

Thanks for the suggestions,

Paul

ChuckW

Be sure and use good aircraft plywood from the hobby shop. You may have to laminate several pieces of thinner ply to achieve 5/8 since it may not be available that thick.

It would be best to epoxy it to the firewall in addition to the screws. The only problem is that means you are stuck with it. If you decide to change engines later, you may not be able to move it back far enough.

There is nothing wrong with your GP motor mount. I'd definitely try to make it work before trying omething longer that may flex as campy pointed out. The length problem has to do with your engine more than anything. The LA series is a bushing engine and they are shorter than most ball bearing engines such as the .46-FX or .46-AX. Once you get the mount spaced correctly though, you should be fine.

jetmech05

you can try fiber glass specialities to see if they have your cowling.....looks like to me the cowling is too far forward....all the ideas given to you will work....

goirish

Hangar 9 makes a longer mount. I have had to use them for my 4 strokes. They come both in the 40 and 60+ sizes.

gunfighterII

It looks like in the first picture your butting the cowl up to the firewall. The cowl needs to slip over the fuse by at least an inch or more.

As the plans show, the drive washer needs to be 4-7/8 to 5" out from the fuse, it seems to me your close.

The cowl needs to attach to the fuse rather than the blocks on the firewall.

Might as well buy the new cowl and start over.

propbuster

My Feedback: (1)

Hayes makes a long mount that won't twist or move and you can cut it down if it's too long for the cowl. See:
http://www3.towerhobbies.com/cgi-bin...?&I=LXK809&P=7
That and a new cowl would get you fixed up.

paully_321

I am mounting the cowl according to the directions. A. It wouldn't fit any further onto the fuse B. It is not put together wrong. C. there is 1/8" of recessed fuse that is designed to accept the cowl...I am on that as per the instructions.

This is the ARF (40) not the kit so there were no plans. AND they don't make this cowl as a piece to buy and start again. They stopped making the arf years ago.

RCKen

My Feedback: (9)

[link]http://www.fiberglassspecialtiesinc.com/cowlkit.htm#GREAT PLANES[/link]

You can purchase a new cowl for this plane at Fiberglass Specialties.

With your current setup, you can cut a piece of ply to extend your engine mount out so that the engine will fit the cowl. Cut the ply the same shape as the bottom of the engine mount, and then drill holes through it that match the holes in the engine mount. Then use longer mounting bolts to secure the mount and the extender block in place.

Ken

gunfighterII

Paully,
My apologies, your initial post said that it was the kit version, so I was looking at the those plans.

No need for a new cowl if you extend it with blocks.

paully_321

Cool!!! No problem.

paully_321

Thanks Ken...I didn't know about that site...The rest is in my plan. Thanks!

gunfighterII

Paully,
On second thought you will need a new cowl. I need to get back to my drink.[

Something is definitely not right here.[] I had the same problem with my UCD 60, mounted it to specs and the planes trim would'nt line up with the cowl paint.