I didn't build one but I found one cheap and have a couple questions for the builders

[RAM]

Someone put a balsa glider/trainer on craigslist today for $40 so I now own one.

It has a motor and folding prop but the motor is not brushless. No servos either.

Other than that, it is fully assembled. It has a 78" polyhedral wingspan, very light open style frame, covered with monokote??.

I have some brushless motors from my foam plane builds. I also have some 9g plastic gear servos.

My questions, finally, ---- Do you guys think the 9g plastic servos are ok to use on a balsa build or should I get some metal gear servos (just elevator and rudder). The control surfaces have real hinges in them and they are stiff but not much stiffer than a foamy.

Second question ---- Should I bother with the brushed motor? I have no way of testing it (assume that I have to buy a special esc for it).

Thanks.

 

[Barron.Barnett]

I'd personally just ditch the motor and drop in a new one if you don't have an ESC for it. You can go buy a brushed ESC for it. My thought is you can probably find an equivalent sized motor that's lighter and performs the same.

Servos, I'd probably go with metal servos. Remember it's not just the weight of flexing the wing but also the forces on the control surfaces. You'd probably be fine with plastic but the extra weight combined with the surface area for the control surfaces would make me want to go with metal to be safe. I've also been known to over engineer things so take that for what it's worth.

Oh, and serious props on the awesome find. I'm going to start paying attention to craigslist for sweet finds.

 

[Joker 53150]

I would agree that going brushless is probably the better route. For the servos, metal or something bigger than a 9 gram wouldn't be a bad idea, especially if you're ording the motor/ESC anyway - keep the plastic gear for smaller birds. I have one glider close to the size of yours and run 9 gram for ailerons, rudder, and elevator. No problems at all with it after a few dozen flights.

 

[RAM]

Thanks for the replies. I'll go with brushless since I have a couple motors lying around.

I was able to figure out what plane it is by searching for the motor (Great Planes Spectra). Turns out NoddRC just rebuilt one of them last year so now I have all the info I could ever want about servos used prop used motor size etc. He did say the design was prone to "tip stall" (oh no, that phrase again!)

Here's his build log http://www.rcgroups.com/forums/showthread.php?t=2121190
https://www.youtube.com/watch?v=Wf1u4p4p1uU

 

[earthsciteach]

Nice that you have Nodd's rebuild as a guideline. That guy is GOOD! Tip stall? Facepalm.

My only comment was going to be, be aware of the significant drop in weight with going to brushess and adjust components accordingly. But, I'd bet my paycheck that Nodd has that covered. Work in some washout at the wingtips to help with that nasty stall characteristic.

Nice score, man!

 

[RAM]

Nice that you have Nodd's rebuild as a guideline. That guy is GOOD! Tip stall? Facepalm.

My only comment was going to be, be aware of the significant drop in weight with going to brushess and adjust components accordingly. But, I'd bet my paycheck that Nodd has that covered. Work in some washout at the wingtips to help with that nasty stall characteristic.

Nice score, man!

What's funny is that my very first post on this forum was about a set of videos from Ken Cashion where he takes an older glider and mods it to take a brushless motor. He went over all the problems he found on weight lost, CG changes, motor power, all in great detail. With those videos I already had a lot of info but finding NoddRC's build log is the icing on the cake
http://forum.flitetest.com/showthre...ideos-on-how-it-s-done-the-basics-of-building

Can't wait to get it into the air. Hope I can find metal gear servos locally.

 

[crispytato]

I'm presently converting a great planes spirit to brushless, which is the same model, but the un powered hi-start version. It required a great deal of nose weight to balance out with the original, and with brushless motors + small servos + lipos rather than Nicads you may need to put a good chunk of battery (or lead) in the nose. that said, this was a very popular model, and is known to fly pretty well when set up right.

Servos are mounted rear of the CG, so moving to mini or micro servos over the original standard size ones will help with the balance situation. I'm planning on putting an 1800mah 3s or similar as far forward as possible on mine, which should just about balance it out without any dead weight. Fitting a bigger pack would probably be a challenge to fit into the fairly slim nose. Perhaps you could remove the pilot bust and fit the battery in that area?

I'd like to see some pics if you have a camera. More ideas for my build can't hurt!

 

[RAM]

I'm presently converting a great planes spirit to brushless, which is the same model, but the un powered hi-start version. It required a great deal of nose weight to balance out with the original, and with brushless motors + small servos + lipos rather than Nicads you may need to put a good chunk of battery (or lead) in the nose. that said, this was a very popular model, and is known to fly pretty well when set up right.

Servos are mounted rear of the CG, so moving to mini or micro servos over the original standard size ones will help with the balance situation. I'm planning on putting an 1800mah 3s or similar as far forward as possible on mine, which should just about balance it out without any dead weight. Fitting a bigger pack would probably be a challenge to fit into the fairly slim nose. Perhaps you could remove the pilot bust and fit the battery in that area?

I'd like to see some pics if you have a camera. More ideas for my build can't hurt!

I'm terrible about taking pics even though I have several cameras. I decided that I want the best of both worlds so I am putting a power pod on it to hold the motor above the wing. I'd like to try slope soaring as well as powered flight with it so the pod needs to be removable.

I found this blog entry and video but no actual plans for a power pod.
http://www.jonshobbies.com/i-wrecked-the-reactor-bipe-time-for-a-new-used-fpv-plane.html (pics at the bottom of page)

Edit: I did find some original plans that I can use with some modification http://manuals.hobbico.com/gpm/gpmg0805-manual.pdf

 

[crispytato]

Just a thought- I've built and flown a couple of pod-based motor gliders, an old kyosho Melody ARF and a conversion of an old balsa design, and never managed to get a particularly wonderful flyer. I could never find a thrust line setup that didn't give weird adverse pitch characteristics. The spirit/spectra is a case I'd think the power pod is less than ideal as a design, with it's balance issues. You'd need to put lead into the nose for sure.

Have you considered just using a folding prop, and leaving the motor in while sloping it? maybe rubber band or tape the blades down if you want to avoid potential damage? You could even have a backup plan for if you get stuck in a downdraft or lose lift at the wrong moment (okay, I admit slope soaring anything that's not an cheap EPP wing scares the crap outta me )

 

[RAM]

Just a thought- I've built and flown a couple of pod-based motor gliders, an old kyosho Melody ARF and a conversion of an old balsa design, and never managed to get a particularly wonderful flyer. I could never find a thrust line setup that didn't give weird adverse pitch characteristics. The spirit/spectra is a case I'd think the power pod is less than ideal as a design, with it's balance issues. You'd need to put lead into the nose for sure.

Have you considered just using a folding prop, and leaving the motor in while sloping it? maybe rubber band or tape the blades down if you want to avoid potential damage? You could even have a backup plan for if you get stuck in a downdraft or lose lift at the wrong moment (okay, I admit slope soaring anything that's not an cheap EPP wing scares the crap outta me )

My original idea was a folding prop. It already has one but on a brushed motor. I do understand the need for more or less weight depending on the setup (after doing some reading). I also found one plane where the guy put a small balsa box in the plane where he stores the lead BB's. He used it for adjusting the overall weight to combat different wind speeds but I think the same box idea will work in the nose of the plane.

 

[RAM]

Finally maidened it today. Perfect weather and very low winds. I'm still too nervous flying and instead of just gaining altitude I panicked the first three tries and nosed it into the dirt. I can't recommend folding props enough after that No broken props!

Eventually I got it airborne but could not get it to turn back to me (I think I forgot to yank after I banked). So I decided to bring it down some distance away. I misjudged the distance of a small group of trees and ended up flying it right through the branches of one. The fuselage came away intact but both wings split in half, the spar (aluminum and plywood) broke in half, and both the rudder and elevator were torn free from the fuse. I had a blast.

The wing halves are so damaged I think it would be best to build new ones out of foam. The balsa wingspan was 78". I'm thinking about a 100" Armin wing to replace it. I've seen videos of 100" Armin wings in flight but no build videos. I'd appreciate any recommendations you guys might have on the wing rebuild.

Thanks