dispatcher418

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hello, i purchased a GP arf super skybolt 60 - 91

any advice on an engine?

thanks

Insanemoondoggie

I use a Saito 1.00 with a 14x8 APC in mine . Great power to weight ratio and never run out of vertical .

The firewall has lots of lightening holes , which makes it a little weak and had to replace mine , as the engine mount was pulling it apart .
The Skybolt is my favorite plane, and looks great in the air.

da Rock

Look closely at the prop/ground clearance for any oversize engine you're considering. 3-blade props can help solve the problem, but it's better to know up front what your engine choice can affect.


Also, keep in mind that the firewall is only 2 layers of liteply. And the upper part of it has no support other than foam and skin sheeting. It would be a good idea to consider laminating a layer of aeroply (real hardwood plywood) to the firewall to keep the motor mount from compressing into the soft liteply. Liteply doesn't stand compression very well.

Mttvannest

One of the guys in our club just flew his for the first time wed. It was the kit version, but it's the same size as the arf. It flew quite nice with a super tiger 75. It flew like an airplane. It won't hover on the engine.

matt

dispatcher418

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Thanks for the help

FlyingPilgrim

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Unless you are flying at extreme altitudes, I don't think there is any reason to go larger than an O.S. FS-91, which is what this plane was designed for. If you prefer a 2-stroke, any .61 to .75 should be fine.

dispatcher418

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what engine did you use?

thanks mike

Jester241

Our instructor has an O.S. .91 4-stroke in his skybolt and it flies great.

dispatcher418

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thanks

what prop?

da Rock

The kit version used to finish out quite a bit heavier than the ARF. And it built a lot of it's reputation with 60s in the nose. Not too many people were into 3D.

So don't think you need more power than 60 2cycle or 90 4cycle. Mine is great with the 60.

ChuckW

I'm assembling on right now and have a brand new Saito 1.00 for it. Hopefully it will be a great combo. I've heard several horror stories about the firewall. Mine seems to be made of good quality aircraft plywood, epoxied and braced with tri-stock. Is there something I'm not seeing or did they maybe improve it?

Jester241

......no clue,lol.

Insanemoondoggie

The firewall looks good from the front , but there are so many lightening holes in the back of the second peice of ply , thst it is very weak and a strong engine will pull the the mount off the plane . See da Rocks pics in post above.

With the Saito 1.00 I have unlimited vertical and will hover on the prop . Thats how I pulled the firewall lose, hanging it on the prop.

da Rock

And they didn't provide supporting bulkheads across the back. Amazing. In the picture you can see they had a horizontal bulkhead about 1/3 from the top that they actually cut the middle out of. I guess they wanted to make the nose lighter.

Also, liteply more often has voids and holes. They reject it when they are on the exterior plys, but don't see the internal ones. And it doesn't stand compression worth spit. You can often tighten down the motor mount bolts and pull the blind-nuts right into the ply. It often happens that blind-nuts tighten easily until they contact the back of the motor mount. The stuff is that poor. It's made to be light first and strong second.