26% Skybolt

[supercub Man]

My Skybolt has a 78"top wing span and a Quadra 50/52??cc with CH Ignition. It is covered with Sig Coverall and then doped. The final paint is the problem I got talked into using Moores Semi Gloss Latex house paint - was told it was easier! Took a lot to cover the plane and I think it has added a lot of weight. I have yet to add the trim colours which will be Flecto Varathane Colours. I will have to shoot another coat of white or just add the trim colours and shoot everything with a coat or two of polyurethane clear, to get the gloss white. But here's the problem. I got tired of the project and put it away a year ago but have recently resurrected it and want to fly it or get rid of it. I loaded it up with all the gear and it weighted in at just under 25lbs!!
Question: Is this too heavy to bother with? Would I gain much by stripping all the covering and going to film (and mortgaging the house in the process). The motor should be pretty powerful but assuming the plane is well built (of course!) will I have a marginal bomb or just a nice flying but not too spectacular bipe? Would anyone have a handle on this? I don't want to spend the time on it if it will really be a dog! The plans are by Dario Brisighella.

[waynek]

Wow,

You ask some hard questions. As is usually the case, you're probably going to get a lot of answers, based on different experiences by other modelers. I have a few suggestions that may help:

1. Make sure you have a problem. You mentioned the weight, but what is the wing loading? What about the thrust to weight ratio? Maybe 25 pounds is not so bad for that size of airplane and engine. What specs do the plans call for? Maybe you could get in touch with the designer and run your numbers by him.

2. I don't know much about paint, but is sanding an option? Someone once said "It doesn't matter how much you put on, what matters is how much you take off." Maybe just sand one section (rudder or something) and you might be able to get an idea how thick the paint is and whether or not you're going to be able to sand the rest of the airplane before the next millenium.

3. If it turns out that it is too heavy, then you really have nothing to lose and everything to gain by taking drastic action:

- Sand it down to near nothing, or;
- Pull the covering, re-mortgage the house, and cover with film or a textured iron-on flim. Beware, I think the textured films weigh more.

4. If your bird is overweight, then what you have is not an over-weight Skybolt but a (soon to be) ARC scratch built beauty. Just peel and go :)

Hope this helped, good luck with it!

Wayne

[scaleguy]

Option 5:

Sell it and let someone else mortgage their house.

You don't want on averweight bird, especially a Skybolt. I was a member of a full-scale club for years and one of the guys had one. WOW what a skyrocket. 360 HP on that puppy was amazing. The owner would routinely takeoff in about 500 ft and pull to verticle and keep going till he was not much more then a dot in the sky.

This baby was meant to perform. I think 25 lbs in excessive for a 52cc aerobatic model... OK for a Sopwith Pup or something but I think you would be dissapointed.

JMHO! :D

[supercub Man]

Yeah you're right! Was talking with Lee Richter, who used to weld up the Cabane struts and landing gear for Dario, (and still does as of a year ago) and he said the plane always did built "heavy" . Dario liked to make sure that the frame was good and strong so lots of 1/4 ply and spruce although I used bass wood which might be a bit heavier than spruce. Anyway I can't build something without trying to fly it - stubborn I guess. If I can get enough thrust from the engine prop combination to make me feel comfortable, I'll give it a go! Otherwise I'll sell it to someone with a 60cc. I'm just going to give it a light spray of trim colours, since an all white plane is hard to see and just take a shot. I never did plan on doing 3D but an occasional roll or loop would be nice! Thanks for your comments.

[ronm]

If It were mine, I'd tear-off the covering and cover it with mono/ultra-kote.

You could probably shave a few pounds, and it would be an
OK sport flyer.

If you don't have unlimited credit at the hobby shop, try the econo-kote covering!

[nony]

What is the wing area, and wing loading??

I have a 60 size skybolt that I thought was way too heavy for the tiny thing wings, but believe it or not, it flies beautifully (does not glide, though...) . I think there may be room for some optimism here....

[supercub Man]

Hi Nony - The Wing Area is about 1650 squares with a weight of just under 25lbs. It has a Quadra 52 with CH Ignition. Klaus at Aerrow Quadra told me he had "worked" the engine for higher performance. I have only run the engine once but I think I tached it at around 7000 with a 20-8 Master Airscrew prop. I was having trouble with the carb as it isn't a walboro so I've changed it to a walboro off a Quadra 41 and will test it further. I'm just spraying some trim colours on it and hope to have it pretty for our upcoming St. Catharines Air Show on the 28th. After that will come a test flight and then the decision to strip or use it as a sport flyer as was my intent! So what think you?

[wells]

Jim,

Take a look at the specs on the real plane, power loading in particular.

http://www.steenaero.com/Skybolt/specifications_standard.cfm

1650 lbs / 300 hp = 5.5

If you stay true to that, you will have a very scale-like flying airplane. I'm pretty sure the Q52 is capable of 4.5 HP? Your plane is under what I would consider a maximum weight for scale flying (minimum loop and turn radius). That is determined from the weight of the full size plane:

weight * scale^3
1650 * 0.27^3 = 32.5

Next, would be to determine the flying speed for your model and picking an appropriate propeller. I don't think 8 inches of pitch is going to give you the flying speed needed for scale-like vertical maneuvers. That's like putting a 10 x 4 on a trainer. It'll fly, but it'll probably stagger through the air as compared to putting a 10 x 6 on it. It's a good hovering or leaf-blowing prop! ;) Your model will need to fly close to 90 mph to have the airspeed required for scale-like vertical performance. 12 inches of pitch is a good starting point, imo.

[supercub Man]

Thanks Wells - That's very encouraging. I will probably run the motor up this afternoon after I cut the @#$%@ lawn. Neighbours will hardly notice the difference in noise! Once I get it going I'll probably gravitate to the field and do some static thrust tests. There are still a few items I need to finish before I actually fly so I'll leave the top wing at home! I'll start with the Dynathrust 20-8 and then test a Zinger 20 -6/10 and a Zinger 22-8. This is my full inventory at present without a trip to Burlington! Once I get RPM readings, I may know better what I have here.

[wells]

I have a MA classic 20 x 10 you can try! If it's nice in the morning, I'll be at the field.

[supercub Man]

Super! - I got the motor running. Not as great as I thought. the 20-8 Dynathrust ran around 6600/6700 and pulled about 15lbs. The 22-8 Zinger ran at 59/6000 and pulled 18lbs. I had to change from the Walboro carb back to the one supplied with the engine, which is a Walboro copy, but maybe the ports in it are larger or something 'cause it runs better. Still not running steady but I think I've got the nack. Needs to have the s...t primed out of it and then it starts with a simple flick! Weather good I'll see you there. Thanks

[Heli_Gal]

I think this Ultimate is the biggest I had seen.. not sure the wingspan though must be longer than your skybolt ?

[supercub Man]

Hi Heli-Gal I don't think my Skybolt is that big. Top wing is 78" and fuse is 60" Maiden flight was last Friday and I am quite pleased with it. Used a 20-10 Dynathrust but waiting for a 20 8-14 Zinger which I think will help more with the climb rate. Got only 65/6600 RPM out of the 52 Quadra so am also playing with it. It has a Zama carb instead of the good old Walbro and I'm wondering if that makes a difference. Would post a pix but can't get the darn thing to work!

[supercub Man]

Tried to attch to first post but wouldn't do it. Hope this works!

[ronm]

That looks great!

But if you need lots of power, use the Dynathrust as a paint-stirrer, and use one of your other props.
Dynathrust is only good if you have too much engine, and want to reduce thrust! :wink:

[supercub Man]

I have already posted some of the results of my test flights under "Large Engine - Carb for Quadra 52" but I'll finish this topic off. I felt after running the engine with the Dynathrust that I should get more RPM so I checked the spark and it was set at about 24/25 deg. BTDC The mark for the magnet was on 30 deg. but the plug didn't fire there. I adjusted this to fire at about 30 deg. I also got a Zinger 20 6-10 prop and went to test on Fri. The difference was astounding. The rpm only went up to 6700+ but the static pull was about 24#+ as best we could guess with our old fish scale! However performance in the air was great. The plane leapt off the ground in no time and climbed out with no sign of dropping off. It rolled, looped and would have flown knife edge out of sight had I let it. With a tweak to slightly richen the High Speed needle and using a 30:1 Mix with Klotz synthetic, I think I now have a great plane to play with. As we get to know each other better it'll be even more fun. The fish scale may not be as accurate as I thought and I may only weigh in at 21-22lbs. Thanks for all the advise!!

[cmcardarelli]

I'm also finishing a bird like this one! How does it flies? Is it gentle? Slow? Stable? Landing is easy?

Thank you!

[supercub Man]

Since I last posted in Sept. 04, I have ripped off the cloth and Latex Paint covering and re-covered with Solartex. I only needed to paint the trim and I was done. No filling etc. I gained about 1 pound. I then switched from sub C batteries to two sets of AA at 2300mah each and put a Zenoah 62 in the nose with a 22 X 6-10 prop. Weighed with a buddy's accurate scales, it comes in at just over 22lbs. The difference in flying is now astounding. I have unlimited vertical and once I got the CG well back, it lands like a feather with very good slow speed characteristics. At this new speed it is very "frisky" and perhaps I need to add some expo. But it is a wonderful flyer and I am now moving on to the Pepino Waco YMF-5 in which I will install the Quadra 52 w/electronic ignition.
I don't know which version you are building but mine is the 26% scale by Dario Brisighella. I have seen the Great Planes 60/90 size Super Skybolt fly and it is a winner as well. Does everything in the book and is a gentle flyer. Good luck!

[waynek]

Glad it worked out for ya.

W

[cmcardarelli]

Mine is also the 26% from Dario Brisighella! I'm happy that is a gentle flyer and everything went fine for you! Do you cutted all the wood by yourself or had paid to be laser cutted?

I'm curious: why are you moving to another airmodel? Got tired of flying the Skybolt? ;)

[supercub Man]

I cut all the wood myself. I have used a Kit Cutter, but only once and I wasn't happy with the results as I had to re-cut many of the pieces again. In my case they cut per the plans and any errors in the plans were my problem. There are plans where the cutter has actually built the airframe and adjusted the laser cutting to correct errors. I don't know how to find these but the $500 plus dollars I paid was no bargain. When I first built the Skybolt, kit cutters weren't very well known and the thought of using them never occurred to me. I am retired so I have the time to cut my own pieces. Also if the plans are a little out, I can adjust immediately and re-cut the part to fit. I find it much easier to cut the parts as I proceed rather than all at once. This allows me to adjust as I build and not make the cutting experience a tiresome thing. I am currently working on a 1/6 scale model of the DeHaviland Dragon Rapide which I had Laser Cut. The rib outlines, drawn separately on the plans, for cutting, were out according to the building plan for the wing. The result was I had over 100 ribs cut wrong - which was not necessarily the Kit Cuttters responsibility - but which would have been recognized immediately if I had cut them. Thus I had to build the wing using these parts and had to make some major adjustments for final assembly.
So suit yourself. A small band saw and a scroll saw is the way to go and how to cut wing ribs is well documented on the net if you do a search. I worked for a printer many years ago and when I first built the Skybolt and I had a "knife die" of the wing ribs outline made for me by a box cutter. I still use this for repairs by laying it on the balsa sheet and gently tapping it to leave an outline which I then finish cut by hand. A gentle sanding as a group completes the job.
No I'm not getting tired of the Skybolt! I have a number of aircraft which I fly from time to time. I tend to spend more time on the one that's giving me trouble as this is the more interesting one and the Skyboly fell into that catagory for a while. I have a 1/4 scale Super Cub with gas but all the others are nitro and I prefer gas. Thus I won't be giving up on the Skybolt but taking both to the field and flying the Super Cub mainly at float flys. The Waco will be my third big gasser. I can fly 7 days a week if I wish so I tend to mix and match a lot. It is true that the more you fly one model the better you get with it. As a result I must spend a few flights, when I switch aircraft, remembering how to fly them! It makes it interesting. I've rambled enough - now back to building!!

By the way, the Brisighella plans build quite heavily. He uses a lot of 1/4 ply. See if you can cut back on some of the weight by switching to "lite ply" where possible and by laminating balsa for strength and cutting back on all the spruce. Use basswood instead of spruce. If you are not experienced in this, consult with a club member who can advise you. You should be able to build it under 20lbs with a little care.

[cmcardarelli]

Thank you for your answer! But regarding the Skybolt plans from Dario, does it have outlines or something wrong that need to be corrected? I'll defenitelly start to build a new one (light and perfect!).

The one I have finishing right now was built by a builder that I paid but the service was not good... he changed some things on the wings and the fuse is too heavy I think.

The problem is that my plans are scratched and the lines are so smoth that some part cannot be viewed, so I'll need a new set of the plans, liking the original draw not a copy from the copy. But I don't know where to get it. I'll try to contact the son of Mr. Dario Brisighella that was the person who sold me the plans I have. Do you have a better idea?
Thank you again! Good weekend!!

[supercub Man]

No, the plans do not have any errors that I can find, although I would be careul when setting up the incidence for the top wing to have it the same as the bottom wing. My plans are much too cut up to copy. I suggest you do a search on the net to find someone who has a set. Just keep it light!

Jim

[Skybolt]

You can contact Dario Brighsella son's. He is still handling the sales of his father plans.

I powered mine with an Saito 300 with 22x10 prop.
Covering is Sig Coverite with Sig dope

Still working on final tuning for test flight but when it put the nose up I get almost a 1 to 1 power to weight ratio.

[Skybolt]

You can contact Dario Brighsella son's. He is still handling the sales of his father plans.

I powered mine with an Saito 300 with 22x10 prop.
Covering is Sig Coverite with Sig dope

Still working on final tuning for test flight but when it put the nose up I get almost a 1 to 1 power to weight ratio.

[Pull Up Now!]

Does anyone have any close-up photos taken of their Brisighella Skybolts without covering yet applied? I have some questions about how these parts go together.
Thanks!

[TexasSkyPilot]

Rick,

Have you started building your yet? I'm curious about the build.

Jim

[Pull Up Now!]

Rick,

Have you started building your yet? I'm curious about the build.

Jim

Ooooooh yes, I've started building it all right. And REBUILDING IT! I finished the scratch built effort late last summer. It took off fiine, was flying around a while, and then the elevator became progressively less effective. I crashed into the forest. It took 3 guys 1.5 hrs to find it. It was a mess!!!!!! We gathered all the parts and I stared at it in the garage for 2 wks trying to figure out what happened. For the final failure analysis and pics of the plane, see this RC Universe thread.

http://www.rcuniverse.com/forum/m_10832283/anchors_10832283/mpage_1/key_/anchor/tm.htm#10832283

Bottom line, the plane is flying really well now and I love it! I have some construction photos if anyone is really interested.

[TexasSkyPilot]

Wow, quite the mess. Losing a hinge pin - as you've already found out - is due to not bending the end of the pin at a 90-degree angle.

Those DuBro horns are great, but every bit of hardware has to compliment every other bit. The clevises used with those should be the DuBro safety-lock Kwik-Links. They keep the horn flange from swiveling. Ball links don't work on those.

You don't need hardwood end-grain, and I would absolutely not use end-grain. Too much stress and too little strength, and that's a real poor exchange for not crushing!!! It'll split right next to the horn. Don't do it. Simply soak thin CA into the wood grain and let it harden. You won't see that crush easily, and the strength will triple.

And yes, of course we're interested in the construction photos! Sorry about those flamers I saw on the other thread, there are many of us who are behind you all the way. Especially when the plane is coming down out of control. Okay, bad joke.:rolleyes:

Jim

[TexasSkyPilot]

Wow - I just saw something impressive. You have built that Brighsella 1/4-scale at just over 19 pounds? I saw the 19.5 pounds after the rebuild, and even that's light. Every place I've read about this, they were making references to 25 pounds.
So, My question is this - Did you do anything special while building in order to keep the weight down? I'd love to see photos of any of those innovations if you have any.

Looking good.

Jim