NewFlyingMan

My Feedback: (24)

Hey there RCUers,

I'm beginning to scratch build a Wendell Hostetler Steen Skybolt and have been losing much sleep over my powerplant choice, or rather the choice I will have to make. There seem to be so many to choose from. I hoping ya'll can give me the down and dirty deeds on what's available, what to consider and what to stay away from.

With some weight mods I am hoping to pull the model into the 18 (optimistic) to 20 (realistic) pound weight range, the original design called for heavy building. The model will have WS of about 76", length of 66" and wing area of 1800 sq.in.. Here is a link to the models site: http://www.hostetlersplans.com/skybolt.html

Obviously I am looking to find a gas engine. It would need to be 1 cylinder for inverted install. I've been looking for engines in the 80cc to 100cc range. I want to spin a 3-blade prop, and ultimately I want it to be capable of 3D. And I would prefer a more compact package so I don't have to open up too much of the cowl.

What are the important numbers to consider?

I'm not sure what to trust. The new Evo 80cc site shows it makes 10.5hp and the DA85 only makes 8.5hp???

Any thoughts would be greatly appreciated.

Keith

Tired Old Man

My Feedback: (1)

HP values are usually not to be trusted. The Evo, DA, and 3w are all great engines in the 80-85cc class. Any of the BME 100 to 116cc twins would fit and be lighter than any of the singles. You might need the weight though.

You might also look at Fox to see if they are still maiking their 5.8 singles, and look around for a used Brison 5.8. The Brison would be an excellent engine and the cost would be in the affordable range. Taurus engines may still have one of theirs on the shelf.

ec121

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??

Jake Ruddy

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I am not sure why you would need more than an 80 on a plane weighing 18-20 pounds, a 50cc will 3D an 18 pound plane. It won't be super pull out but will get the job done. A 100cc or more is a complete waste and will way over power the plane. You can 3D a 28 pound plane no problem with a 100.

If you want light and smooth I would be looking at the ZDZ 80. More power than you need let still a light and smooth engine.

Bass1

I kinda like the newer ZDZ 80 as well. Should be more than enough for that airframe. http://www.youtube.com/watch?v=81ntfggJfcA

NewFlyingMan

My Feedback: (24)

Thanks everyone for the input. I've be surfing the engine sites and I too am starting to like the ZDZ for this project. I've been looking at 80-100s because I'm not quite sure how much weight I will be able to shave off, although I am fairly proficient at moding airplanes in that favor.

I just want to make sure I have enough engine to go around if the weight doesn't come off as much as I am expecting, but even at the manufacturers spec of 24lbs, it looks like the ZDZ Super 80 RV-J will get the job done well and given its apparent performance the price is reasonable.

Keith

NewFlyingMan

My Feedback: (24)

Yep. The ZDZ80 is just about right. Forget about written specifications...video specifications will work!!!

mrbigg

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That's what I bought for my 70" Cox Pitts. People say they come in at 18 pounds and being a bipe, they suck up the power with all the drag. That's why I went with the 80.

Tired Old Man

My Feedback: (1)

The way the old kits always seemed to work out, I simply added a couple pounds to the anticipated finished weight. Went with engine sizes from there after factoring in a little for the additional drag of a bipe. If it comes in light the 80 will do it, but the Skybolt is a "muscle bipe" so spare power is somewhat nice. I've had a few Skybolts (kit built) and all of them finished up over the "listed" weights. Interesting that the one I painted was the lightest one...