Was considering the G.P. Super Skybolt Arf and would appreciate hearing from others who have this plane.
Is the OS91 four stroke adequate power or would it be better with the 120?
I need to purchase an engine for this plane and was looking at having enough power for those unlimited verticals and also thinking how the plane would balance. I read an article from one chap that had the 91 on the front and plane was quite tail heavy. He moved his battery pack alongside the engine mount and still had to add I believe about 6 oz of lead to achieve balance.
I have not checked the weight difference between the 91 and 120 but would hate to have to add to much lead , if with the 91 she comes out to tail heavy.
What condition did your arf arrive in. How well was the covering....lots of wrinkles in the covering? and were you successful removing them with your heating iron?
How was the build, airframe seem strong enough, any weak areas? etc....
Any info you could provide me with would certainly be appreciated.
Thanks and best regards

Mike

This plane is an awesome flyer.

While not unlimited with the .91 it is quite respectable with it in.

As far as the C.G. don't believe what you read.

Everyone puts a lot of weight in the nose to get the C.G. to the recommended range... as it appears tail heavy if you go by the manual.

Then they fly the plane only to discover that this way it is too NOSE heavy.

There is NO need to move the battery pack forward with the .91 FS engine. It's perfect under the canopy.

IMHO the manual is off by 1" at least.

A larger engine would add that much more weight to the nose.

Any wrinkles come out w/o problems with a heat gun. I use a hot gun to cause the material to bubble then pull tight, but you must be careful NOT to heat the area around seams.

Re: Weak areas.

The gear area could use some re-inforcement, but ( Da Rock will chime in here ) the firewall needs re-inforcement.

He advises putting a sheet of thin ply over the existing firewall to add additional support.


My Skybolt is well on to it's second century of flights now.

I have an OS 91 fx I would like to use in a Super Skybolt. I know some have gone to a 1.20 two stroke and had good results. Can anyone tell me what to expect with the .91 fx in terms of vertical performance?

Given that the 2C .91 FX has a higher BHP rating than the .91 FS, that should give the plane unlimited vertical.

You would need to re-inforce the firewall though.

I have the super skybolt ARF. I have the OS 91 four stroke in it and opjose stated everything correct. The fire wall on mine started to get loose and I never had any hard landings with it, but a very easy fix to beef that area up. Which I did and have never had another problem. I think I may have three or four gallons of fuel thru it now.
The covering it real good, or was on mine, just be carefull around the checkered area because they seem to be removed real easy if not careful.
Mine did come out tail heavy, but I did add a smoke system. The build was very easy and went togather great. I think anyone who gets a skybolt will love it. I know I do mine and if mine should have a mishap I will replace it in a second.

I guess some folks are going with the 1.20 AX. I'd love to have that kind of performance, but a new engine just isn't in the budget for this ship. I read through the other long Skybolt thread and it doesn't seem like the guy flying the 91 fx was too jazzed with it.

You have to take what you read here with a grain of salt. One man's rocketship is another mans slug.

I've flown my skybolt with an OS .75AX spinning an APC 14x6 at an even 10,000rpm and the plane flies very nicely indeed. The vertical is excellent. It's not unlimited but it's almost there. My own opinion was the model was perhaps a little too fast so i contemplated slowing it down with a 15x4 but never got around to trying it.

I'm sure the .91FX would be even better. It weighs the same as the .75 and has about 20% more power.

I'm now flying my skybolt with the OS .91 Surpass II 4-stroke and find it slightly less powerful than the .75AX with the APC 14x6 (400rpm less) but with a Graupner 14x7 it flies very well and with more pull than the APC 14x6 and 14x7 props (those graupner super nylons pull like a tractor).

I agree with what has been said about the CG. Mine is also a bit further back than the recommendation.

As CustomPC said, I'm flying mine with a .91 Surpass III Pumped and it's just about perfect, but it could stand a bit more power for the verticales.

That said, I'm not contemplating changing the engine for any reason. The plane is great this way.

I have one, it's a 60 to 91 size plane. I have a Magnum 70 on mine, it balanced out perfect, fly's like it's on rails, but could use a little more engine, but not much. A 91 four stroke would be awesome in my opinion.

I've got one. Been flying it since about this time last year. It's an excellent choice for anyone beyond an absolute beginner.

The original that was so popular was a kit airplane that finished out over TWO POUNDS heavier than the ARF that's being sold today. TWO POUNDS !! And almost everyone flew them back then on 60s. And 60s back then were just a slight bit less powerful than what we've got today. And they flew great. Will an OS91fs pull it? Yes, very, very well.

I fly mine on an OS61FX. It flies almost as well as the other one at our field that has a larger engine on it. Biplanes have a way about them that tends to make overpowering them a waste of time. Forget about the 1.20. It'll be a waste of time and money.

Does my Skybolt have unlimited vertical? First off, that term "unlimited" usually means "it went basically in an up direction longer than my limited attention span". I do prop tests with everything I fly and they include a vertical check. This airplane with it's 60 goes as nearly perfectly vertical as I can fly it way farther up than two vertical 8s (one on top of the other). Part of the deal is prop selection and needle setting, but bottom line....... a 60 will pull it vertical more than adequately.

His airplane isn't your airplane. Nor is it mine. Each one is assembled by people who might as well be assembling Barbie Dolls for all they know. If heavy wood is what they got when they assemble the aft bits, it matters not to them. They couldn't care less. And they're the ones who may or may not glue all the parts together. Sound like I'm carrying a grudge? Nope, not at all. Just telling it like it's been for the last couple of years. If we are to do this hobby with any hope of success, we've got to recognize the things we need to deal with. Glue joints without glue and ARFs that show an amazing range of weight distributions is just a fact of our hobby.

Covering is a fact of our hobby that most expect. I tried to use a gun on my Skybolt, but the sucker has so many layers upon layers, it wasn't appropriate for much. You really need to use an iron wherever there are seams. The airplane is mostly seams everywhere. Monokote when layered can beat your brains out. Mine took a session with the iron before assembly. And being layered Monokote, a fair (or unfair) amount of the wrinkles came back somewhat after the first outing. Put sun on it and bring it back in the house and some of the originally bad wrinkles come back just enough to let you know they aren't happy being stretched flat.

Any weak areas?

See the picture of the firewall? That resulted from what could realistically be called a somewhat hard landing. That firewall is two layers of liteply. Firewalls made out of liteply are a fact of our hobby. They're not the smartest of design solutions. And if you look closely at the picture you can see that the upper half of the firewall is attached to foam. The foam is sheeted in thin balsa. That's it. The upper half of the firewall is "supported" by picnic cooler foam and 1/16" balsa.

Not a weak area, but something worth considering.......... see the picture of the aileron rigging. There is a long thread about this model that includes a discussion about that. I'd suggest doing it, mostly because I was the one who figured it out. The airplane obviously flies good with the mfg supplied stuff and design. The original discussion covers that and more. Mine flies without any problems. And that rigging actually took less time to do than it would have their way.

It's one heck of a good airplane. They all have warts from the ARF mfg's. These are little ones and can be easily cured.

Very good!

I'll have to remember that definition.

unlimited would be all the way to outter space. lol I wanna see this !

Perhaps unlimited means to the limits of visibility? I guess a smaller plane wouldn't have to go up as high...