Completed building first glider. Couple questions - RC Groups
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Mar 20, 2007, 05:18 AM
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Completed building first glider. Couple questions

I have just completed building up my first glider, an "Electrofreshman" that I have had since 1991 (72" wingspan). This is the first plane I have ever built, I made a couple of mistakes and found the instructions terrible. I still need to do a final sand (balsa filler in places) and start on the covering. I have ordered a Master Airscrew flight pac 3.0:1 with folding prop (off ebay, $19). I am not sure if it will fit, or provide ample power. Any suggestions on other motors, servos or esc's would be greatly appreciated. In searching some of the threads I have never seen this glider before. I am curious about the strength of the wing, perhaps there is something I can do to reinforce it?

I ran into one problem building the wing. The instructions indicated proping up the outer wing tips 3.5" when glueing. I ended up with about 4.25" on each wing tip, increasing the dihedral. Having never flown I glider, I am curious how this will affect the flight, any comments? I included some pictures.
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Mar 20, 2007, 02:10 PM
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It should be fine It will be very forgiving I think.
Mar 20, 2007, 08:14 PM
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Resurgam's Avatar
That motor set should work fine. The extra dihedral will just make the plane a little more stable.
Mar 20, 2007, 09:46 PM
Culper Junior
You're heading in the right direction. I use Master Airscrews a lot. Try to keep the servos as far back as possible, maybe under the wing trailing edge, then receiver, battery, and finally, motor. You should be able to move the battery back and forth to achieve the correct center of gravity. I lay a strip of velcro in the fuselage bottom and one on the battery, then the battery stays put and I can adjust the CG for windy weather or calm. Don't let someone convince you brushed motors and nicads are no good. They're fine for your glider, it just won't go straight up. Looks like you did a good job building. If you are concerned about wing strength run 1" wide fiberglas reinforcing tape from wing tip to tip, on the bottom, under the main spars, after covering. Also. Tower hobbies sells a 1900 ma nicad battery by Electrafly for around $20. I have 3, good power source. Don't worry about the dihedral, more is better, less is bad. Jim
Mar 21, 2007, 02:43 AM
Registered User
Thanks for the advice. I haven't received the motor yet, but hopefully it will fit fine. I don't really have a clue how to mount it, but I'm sure the kit has instructions.

Just one other question, how much stronger will the covering make wing, fus etc...
Mar 21, 2007, 07:50 AM
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Resurgam's Avatar
Just one other question, how much stronger will the covering make wing, fus etc...
Depends on what covering material you use. Monokote seems to add a good deal of torsional stiffness to the wing which is good as it reduces any tendency to flutter.
Mar 21, 2007, 09:09 PM
Culper Junior
most iron on coverings will add stiffness as long as they adhere well. I have always used monokote but lately i have talked with several fliers who claim Ultrakote is much easier to work with, so the next cover job will be with that. just follow the directions that come with whichever covering you choose and it'll workout. Keep us posted with your progress! ps in my previous post i meant to say to lay a strip of velcro on the INSIDE bottom of the fuselage, under the wing, NOT the OUTSIDE of the bottom. (but you may have already figured that out)
Mar 22, 2007, 08:20 AM
Registered User
My master airscrew 3.0:1 motor and prop just arrived. There is no way it will fit. The front motor ply plate on the plane is only 1.5" in diameter. The gearbox on the MA is offset, it would be sticking out from the plane at least an inch. I know some people just mount that on the outside sticking out the side, I don't want to go that route. Can someone give me a suggestion of a motor that has less diameter, with a gearbox and still give good power.
In the front motor area of my plane I also have triangle reinforcement as seen in the pic, making the area even smaller. How on earth do I fit a motor in there?
Thanks for the help.
Mar 23, 2007, 03:21 AM
Culper Junior
Most pure sailplane noses taper to a point which sometimes becomes too narrow as you found out. And sometimes because of that taper the motor sticks out too much and looks ugly. As a result it becomes necessary to modify the nose either by removing the first couple if inches or fairing the motor in with soft balsa pieces. Shortening the fuse isn't as radical as it sounds since the CG might be too far forward with the motor all the way out front. I usually remove enough of the fuse until there is enough cross sectional area to fit the motor. This also moves the motor back so balancing is a little easier. Add a 3/8" piece of balsa to the top hatch and sand to fit /fair in the gear housing. Also don't forget with the Master Airscrew it is necessary to mount the gear housing directly to the motor, don't be tempted to sandwich a bulkhead between then for mounting purposes. You could buy a motor with planetary gearing but that will cost more than what you spent on the MA. If appearances are your worry,99% of geared units are offset so everybody's used to seeing them (how often do you see a glow engine faired in?) If aerodynamics are your worry in isn't going to make any noticeable difference.Yes it's extra work but so is making gravy, but it is worth the effort. What you have is workable, it just boils down to your preference. Please keep us posted. PS nice worktable!
Mar 23, 2007, 08:40 AM
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Resurgam's Avatar
I don't think shortening the nose will help much, there doesn't seem to be a lot of taper there. As Aeronca says, a planetary (in-line) gearbox will cost more - see for 500-size boxes. The only other alternative to letting it all hang out that I can see is to rebuild the nose - maybe by adding something like a really high canopy to cover the gears. That probably would be quite ugly anyway.
Mar 23, 2007, 12:02 PM
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rdwoebke's Avatar
Many gliders use planetary (inline) gearboxes. The gearbox has a smaller frontal footprint. They are more expensive, as an above poster noted.

This one might fit your motor, if it is a speed 500 and is smaller:

Or this one:

I order from that place quite often.

BTW, you can run prop sizes, cells, and motor options through this free online calculator and get an idea for in flight thrust, pitch speed, motor current, etc.

Good luck. Plane looks nice.

Mar 26, 2007, 09:09 PM
Culper Junior
So what's up? Still using the MA or did you switch to something else? Flying weather is here now gotta get it finished and in the sky!
Mar 27, 2007, 07:09 AM
Tree Hater
zeuglodon's Avatar
Originally Posted by rgillies
Thanks for the advice. I haven't received the motor yet, but hopefully it will fit fine. I don't really have a clue how to mount it, but I'm sure the kit has instructions.

Just one other question, how much stronger will the covering make wing, fus etc...

I have used them all and my advice is Hangar 9 Ultracote.

It is the US version of Oracover. Nothing applies easier or looks better.
Mar 27, 2007, 10:59 AM
Registered User
MrThermal's Avatar
Looking @ your pic's ... It would be a good idea at this time to install some
verticle grain shear webs between the top/bottom spars.

Takes a little time, but you will have a much stronger wing. Much less chance of folding up !

Shearweb from center to polybreak on each side with wood glue. Looks like
3/16 or 1/4" thick stock would work. A good snug fit & a little wood glue,
and lots of sanding will be worth it.

FWIW ... you may also want to consider a geared S400 with
2S lipo for power. That '05 is pretty heavy ! ... maybe even an
outrunner ... all depends on if you are looking for a warmliner or just
a sport floater ... decisions -decisions *
Mar 27, 2007, 02:51 PM
Registered User
I haven't choosen another motor, yet. I am not going to use the MA, it is just too big. I think I may do something brushless, they seem to be a little smaller and lighter. I will be starting on the covering sometime this week. As far as the sheer webbing, should I run it all the way along the wing? The wing does have sheer webbing but only near the middle.
Any suggestions on a good brushless motor.

Thanks for all the help.

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