Hey guys. Just did the maiden flight yesterday with my new Skybolt and it flew just as expected. I used standard set-up with an OS 91 two stroke. Flew great with just a click or two of up needed. Laterally it was fine (but I had added about 2 oz of weight on the left side in the servo compartment).

My question is prop for the OS 91. I have a 13x8 master airscrew on now and after two flights, it seems a little fast. I like a lot of pulling power and not so much speed, so I was thinking about a 6 prop, but I am worried a 13x6 will be too much rpm. Does anyone have a 14x6 on a OS 91 and how is that performance?

Thanks! - Bill

I use a Graupner 14x7 and love the performance

I have a 14x6 on the very same OS91: runs very well and pulls really hard, give it a try. BTW I'll move to a 14x7, the 6 prop is a little too slow for me.

Try a Graupner. You can pull stumps with these things:

http://www.hobby-lobby.com/14x7_prop_391_prd1.htm

Thanks guys! Just ordered a 14x7!

I have the YS 1.10 in mine. Pulled the firewall right out of the front of the fuse. And yes, I did reinforce the firewall. It happened right on final about 1 foot off the ground. I was flaring and the whole plane dropped. It spread the landing gear, but that was the worst of it. The break off the firewall was a clean break, so it was an easy fix.
I also have VERY fast coreless motor servos. This biplane is amazing!

that's scary......how many flights did you have before the firewall came off?

i'm just getting ready to mount a YS 110S in mine.
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after examining the ramains of my first SS i can see where pinning the firewall may prevent this, but now i don't know.

I was running the APC 14x6 on an OS .75AX which turned the prop at an even 10,000rpms and found that it was a good match for the plane.

Your OS .91FX should turn that prop about 500-700rpm more and would be even better.

It was my 9th flight.

This combo is the most amazing I've ever flown. This bipe deserves this engine. I would guess the kit would hold together better, but I think the arf firewall can be strengthened. I'm considering using fiberglass outside and under the cowl on top of the internal reinforcement.

Weight is not an issue- Believe Me!!!

I was looking into my super skybolt and it looks like great planes is adding tristock to reinforce the firewall now, has anybody else noticed this?

Yes, it seems that now Great Planes adds tristock at the left and right sides behind the firewall. I was planning to power my SS with a new FS-110alpha, yet the extremely high cost of glow fuel here in Greece changed my mind and I'm now waiting for a RCGF 20cc engine to come. The other owner of a SS with a Zenoah and his reports were also a reason. What I did to reinforce the firewall was to somehow "bolt" it to the structure behind it. Below are 3 pictures, the first one showing the 2 holes opened on the firewall, the hatch to be able to work behind and the 2 "bolts" (notice their shape), the second one shows the back side of the firewall with the reinforcement installed (and you can see the tristock at the sides) and the third the final front side. I still do not know if I'll have to trim the heads that protrude, but I guess that with a gas engine on stnad offs that will not be necessary.
As you can see at the first picture, the sides structure does not fully contact the firewall, and that is because the inside lamination of the firewall is cut slightly bigger. So the sides only contact the firewall at half its thickness. Do you think that epoxying a stripe of fiberglass around the firewall would be necessary? Weigth is an issue with a gas engine in front, though I guess total weight will not exceed the one of the kit.

Wasn't that tri-stock there in the first batch? I find it hard to believe that it wasn't

you would think so..........i know that the 2 areas that had tri stock were all that stayed together after my crash.
the opening of the bottom to reinforce the FW for animal engines seems to be a necessity however..........i am amazed at how well ARF's are constructed, but the FW attachment on some leaves me scratching my head.
i know it's the reason why they recommend the lower powered engines, but with the Skybolt it's like buying a Corvette with a straight "6" because the frame isn't strong enough to hold an "8"...................

The way I see it is:

The original Skybolt kit was fantastic, but it was heavy. This in itself wasn't too bad, but I added a smoke system to it (Pump, servo, battery, etc) which made it REALLY heavy, but it was still a blast to fly.

But then 3-D came along and everyone was on a "LIGHT-AS-POSSIBLE" kick. So when GP designed the ARF, I think they may have gone a little overboard on the lightening.

But personally, I think the biggest mistake they made was not keeping the way the top wing and interplane struts are mounted. On the kit, this was the best system I have ever seen - quick and easy. but on the ARF, it's not only a PIA to get the top wing off, but you HAVE to take the top wing off first to get the bottom wing off. So if you want to get at the radio compartment for something minor, you have to disassemble the whole thing [:@]

EXACTLY!

I don't think it would hurt at all. Weight won't be an issue, you'll be fine.

There was tristock on mine, but the left side didn't even contact the firewall. Apparently, I didn't add enough reinforcement either. However, after getting it all back together, no one can tell it ever happened to begin with. I'll be adding fiberglass on the outside of mine. She is just too sweet to not put into the air and beat the snot out of! [8D]

how bout tail reinforcement?
think it's necessary, such as some CF rod on diagonal from ruder to stab?

I don't have any issues with the tail sufarces. Just seal the hinge gaps.

I am using a Saito 125 and that's what I did. Used some thin carbon fiber rod.

R/C Foolish

Do you think reinforcement will be needed with O.S. 110?

I would.

I've put the new O.S. 110 in my skybolt and the spinner did not fit. I had to bore out the back plate just a smidge. after I did that I realized the vess props I had purchased were'nt going to fit the great planes spinner also, so I just went ahead and bought a wide blade spinner from tru-turn.

just to be 100% sure.. you check the CG with plane inverted. this is my first bipe</p>

Nope, with the plane upright.

The C.G. is measure from the leading edge at the center of the TOP wing.

Formaiden andfirst flighs I set the CG slightly forward. When confident with the new bird, I removed weight from the nose to feel the plane just right. I think fine tuning CG is somekind of subjective matter.</p>

Nope, the CG is measured on the top wing where the interplane strut is located