I just read the review for this plane in MA. It looks like a great plane to fly. I am thinking that this will be my next plane as I have a brand new Magnum .91 four stroke laying around needing a home. I looked on Towers web site and compared the ARF to the Kit. The ARF is lighter in weight than the Kit. Why?

Where did they shave the weight off from? Is it as strong an airframe?

If anybody knows, I would appreciate the info.

Thanks, Vance

The kit has alot of solid balsa, blocks few lightning holes etc. The kit is of good quality but must be 10-15 year old technology. This is one of the best Biplanes available. Mine is a kit build any now is almost 10 yrs old. I shoe horned an OS 1.08 2 stoke in mine after starting out with a .61 to a 1.2 four stroke and then to the BIG 1.08. I have flown the ARF and it handles great, a little lighter on the sticks than my kit built but both are super airplanes.

be sure to read the thread here about this bird...................yes it is strong, but it wouldn't hurt to beef up the firewall area...........otherwise it's good right out of the box.
they shaved weight by using interlocking construction and cut lots of lightning holes.
mine is powered by an OS.91 surpassII and came out at 7.5 lbs
it needed 2 clicks of up elevator trim and nothing else.
i'm still fooling with the CG which is at this point in time, 3/8" back from suggested.
the landings are something else............this bird lands like a trainer.
takeoffs are straight as an arrow.
flying it is a whole nother program............it is a blast, and it'll doing anything you ask..........right now i've been doing the inverted snap rolls as Mike (Minnflyer) talks about.....really cool stuff.......oh yeah, i liked this plane so much i bought 3 of them, but have since gave one away to a buddy of mine.

I wonder why they don't update the kits construction to match the ARF?
I'll look at the other thread.

The use of foam in the turtle deck of the fuselage contributes to the lightness of the ARF. This is one of my favorite planes and with an OS 91 Surpass II it really performs.

Hi vrhoward1122.

I was just reading your post and thought I'd chime in here. I work in the R&D department at Great Planes. Although I didn't work on the Skybolt (ARF or Kit), both were developed in the shop where I work and I've worked on many other GP/TF kits/ARFs, so I think I can answer your question.

Actually, Kirk RC already hit the nail right on the head; the kit was developed quite a while ago--back before lightweight construction was more of a priority than it seems to be these days. In addition to the demand for lighter-weight models, ARF construction demands a higher level of simplicity for mass production. The combination of demand (for lighter models) and simplicy gives you a lighter model.

Tim

I'll second everything Summerwind says.

Since i've had my Skybolt i've been bitterly disappointed with every other ARF i've had. The Skybolt is just so much better than anything else on the market. The suggested OS FS .91 Surpass II is a perfect match for the airframe and it flies (and looks) like a dream.

I love that i can fit it in a small hatchback fully assembled and ready to fly. It always amazes my clubmates when i pull it out of the car ready to fuel and fly.

Thanks for the input guys. I think I will get one of these. I was thinking the price was a little steep, but everyone who has one seems to love it. So I gather from the other thread that the firewall issue is the only deficiency. I will reinforce the firewall.

I have been building a GeeBee Tiger Moth and it has been a hard project I'm not sure I was ready for. GeeBee (who is no longer in business) didn't seem to believe in even die cutting parts. They were just printed on balsa sheets and I had to cut and carve. It was basically a scratch built model, they just provided plans and balsa.

The ARF will be nice to have something together and ready to fly relatively quick. Was just worried about the quality. The Skybolt is a beautiful airplane.

If you use the suggested .91FS then the firewall is not an issue. The pictures shown of the firewall ripped out are the result of a crash when the pilot flat spun it and pancaked it into the ground.

Also those that have overpowered the plane buy putting anything more than a Saito 100 should think about reinforcement. I'm still flying mine as it came out of the box and have had no issues with the firewall. I would check the gluing of the servo tray. Mine came loose after about 25 flights but i detected it before it caused a crash.

The only gripe i have with the ARF is that the checkered covering under the wing is not MonoKote like the rest of the covering.

I powered mine with the OS 1.20 AX. Even though it's a larger engine, it fits just fine under the cowl. I did reinforce the firewall at the time of construction (nearly two years ago) and have had hundreds of trouble free flights. It is no understatement how good this plane flies. Two other pilots at my field have also powered their Super Skybolts with the OS 1.20 AX with complete satisfaction. The second photo shows the before and after of how I increased the cowl opening for better engine cooling

Are they aware of the issue with the firewall?

Do you think this may be addressed?

IMHO it's the only negative with this wonderful plane.

The firewall is fine as long as you don't seriously overpower it or crash it. I have around 70 flights with an OS 91 Surpass II and the firewall is as solid as ever.

You may want to check out Da'Rock's pictures of the firewall after it came off on him.

He neither overpowered it or crashed it.

The pictures illustrate the problem best...

Ah...... Not true.

Da Rock says he pancaked it in on a flat spin when he punched in the firewall.

The pictures of the firewall also include the cowling in the background. It's not very sharp in the picture but it's quite interesting. When we walked up to the airplane, everyone thought that nothing was damaged. The cowling was almost perfect. The attachment bolt holes were slightly cracked, but that was it.

The cowling looked perfect. The impact was gentle enough that nothing really happened to the cowling. It's flying today. Matter of fact, here is a picture of the airplane last time out. That's the cowling that came in the ARF box. Notice any damage? The bolt holes have been reinforced inside to reinforce them. But that cowling stopped the engine from moving back any farther after the firewall failed completely.

The firewall failed completely in a situation that did nothing more than cosmetic damage to the fiberglass cowl. That is an issue no matter what engine you choose. BTW, that is the original OS61 in the picture. It's been in the airplane since day one.

You're right. Your firewall is as solid as ever.

Liteply is not always going to fail. But it has almost no excess strength at all. And it is very subject to poor internal integrity. And there is little or no way to check to see if the interior ply is even there. And it is very easily crushed by compression. It is seldom composed of even one layer of hardwood in it's three layers. And two of the layers are usually nothing more than veneer thickness.

It's use is high risk for firewalls.

Will it always fail for everyone? Nope.

Is it a smart choice of material to use in a firewall? Nope.

Since the experienced guys at the field discovered the almost universal use of Liteply in ARF firewalls, we've been inspecting them fairly regularly. And every one of us has found motor mounts crushing into them, cracking across them away from the mounts, and every one of us has had reason to reinforce at least one firewall in an existing model. And they all had a firewall that was as solid as ever.

Liteply is marginal as a firewall. It's easier to apply a layer of aircraft ply when building than later. Thin aircraft ply, just one layer, seems to be perfectly adequate to make up for Liteply's weaknesses. Why the ARF mfg's don't use just one layer in the pair they almost universally install is beyond me.

Well, actually "he didn't crash it" is true as a description of the violence of impact.
And it's true that I said the damage came at the end of a flat spin. But I also characterized it as really nothing more than a flat, hard landing. It really wasn't a crash in terms of violence.

What amazed a couple of us experienced guys was that the impact was so minor the cowl took no damage but the firewall was trashed. And that it was obvious the cowl had stopped the engine from going anywhere.

Keep in mind that the upper 1/3 of that firewall is attached to almost nothing. And that for some unimaginable reason, the cross bulkhead that is highest behind the firewall has the center removed. No lie. The picture showing the hole shows a horizontal bulkhead that appears to have it's center "crashed out". There is no center to it. Nothing was crashed out. It's intact from when it was installed. They removed half that crossmember when they laser cut it. There wasn't any "cross" wood in that thing when it was installed. AaaaaMazing!!! They didn't need the room for the gas tank. It's not even close to the firewall. And they certainly did not need to reduce the weight as much as that firewall needed the support. amazing....... The upper third of the firewall is glued to foam basically. Foam covered in 1/16 balsa.

it may also be smart not to PANCAKE it into the ground....................

Funny, but that was exactly the advice I got when we were bringing the sucker back to the pits.

One guy even said that was the shortest landing he'd ever seen.

hehe........you know i just had to poke you a bit on that one...............mine flies with an OS.91surpassII and has been fine so far, but as a long time builder/flyer of models of all types, i agree with you that the firewall should have had at least one plate of 7 ply 1/8".
and the funny thing is, the normal "liteply" that is used is the same stuff we all buy from Midwest that has "not for aircraft use" stamped on it.................maybe GP felt that "if we use two pieces, who'll complain"..............LOL

I'm just curious if the Skybolt firewall has failed for anyone else that hasn't crashed their plane. And sorry, a flat spin into the ground is a crash. There are a lot of Super Skybolts out there and I'm sure the firewall could have have been done better, but under normal circumstances, has it failed for anyone else?

Hi opjose.

As I stated in my first post in this thread, I am familiar with the Skybolt ARF, but I never worked on it here at Great Planes. But I didn't want to dodge your question, so I'll try to answer you anyway;

First, I don't know if anybody at Great Planes is aware of any issue with the firewall on the Skybolt ARF. That doesn't mean nobody is aware of an issue, it just means I don't know if anybody is or isn't. But unless something becomes a really big issue/problem, usually only the guy who worked on the project is the only one in R&D (besides the R&D manager and his boss) who may know about it. Not all of us know every thing about every model because we are mostly focused on our own projects.

Now, to try to understand what you are talking about I've read the posts in this thread following my previous one from yesterday. I see there is some disagreement whether there even is a problem.

All I know for sure is that if anybody has a product from Great Planes that they feel is unsatisfactory or defective, they should contact our Product Support department (info in the instruction manual). I also know that, for the most part, Product Support is usually very gracious and cooperative in resolving problems.

I didn't mean to turn my answer into an advertisement, but the bottom line is that I know of no problems with the Skybolt firewall, but if somebody does have a complaint they should go through the proper channels. Each case will be examined separately with all the necessary details (what engine was used, how/when did the failure occur, etc.). Then, the problem will be resolved.

I hope this answers your question--at least partly. [sm=49_49.gif]

Tim

As DaRock pointed out, it seems that the firewall could use a bit more re-inforcement as he indicated.

It would be nice to see this slight design change implemented, as IMHO it would complete this otherwise exceptional plane.

The firewall of the first Skybolt ARF to show up at our field came loose during flight with no previous crashes or PANCAKES. That is why I reinforced the firewall on mine during the build. It's easy to do so why not add some insurance. Another issue another pilot and I had was the servo tray coming loose. A little tri stock on both sides of the tray took care of the problem.

Well, It looks like I started another thread for this plane. Didn't mean to. Didn't look far enough into the posts in this forum. However, I will know to reinforce the firewall and servo tray now. All good info, Thanks.

I have Harry Higgly's all about ARF's and will go through their recommended inspection on this one also.