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Balsa slope soarer - 3m - wing issue?

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Old 03-30-2015, 11:15 AM
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bjmcgeough
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Default Balsa slope soarer - 3m - wing issue?

Hi Everyone,

I am new to this forum, and also new to slope soaring, so I will greatly appreciate any help! I decided to move from power to sloping when I acquired a lovely sailplane from someone's old collection. The 3M Bala wing is separated into 3 parts and fits together using stainless steel rods (see photos) which insert into brass hollow tubing. However, there seems to be no indication of a locking mechanism for the wing, and I am worried that it doesn't take too much force to remove the outer two wing sections from the main centre panel.

I have no information on how the plane flew before, maybe the wing was secured with tape? Hopefully the photos explain this better than I do!

Once again, I would greatly appreciate any advice,

Regards

Bradley
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Last edited by bjmcgeough; 03-30-2015 at 11:18 AM.
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Old 03-31-2015, 03:02 AM
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I'd say you're right, the wing parts are held together with tape. I have a similar glider, see pictures.

I use clear Polyester tape because (1) it's stiff and (2) doesn't stick too much. Problem is to get the tape off after flight without tearing the wing covering off. That's also why I don't put a piece of tape around the whole joint, what would seal the gap and would be aerodynamically better. Instead I put 4" strips across the joints, one on the upper side and one on the bottom, about where the airfoil is thickest. The strips hold the parts well together but will simply break in a hard landing. That spared me some damage because the outer wing parts just came off without breaking.

By the way, I think what you have is a thermal ship, not a special sloper. You may use it on slopes as well but it won't fly as dynamically and fast as a real "slope razor". Meseems your wing has spoilers to help escape too big thermals and for landing approach control. The airfoil of your wing looks similar to that of my wing, which is a SD7037 and a typical, classical thermal airfoil. And did I notice correctly that your wing has not even ailerons? That would be typical for a thermal ship but not good for a sloper.

I don't know the type, but I think you will enjoy slope and thermal soaring with your airplane. Happy soaring!
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Old 03-31-2015, 11:28 AM
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That's most certainly a thermal soaring model. As suggested by all means use it for some slope flying but don't be surprised if anything more than a light to moderate wind causes it to become almost uncontrollable. Especially during the landing approach where it's typical to have to come down through the rotor turbulence found behind the lip of the slope.
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Old 03-31-2015, 12:11 PM
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Hi UStik,

Thank you for the advice! That's a nice glider you have! I now see that it may not be the most ideal slope soarer, but I don't have very high expectations, I would be happy just to get it in the air. I plan to install ailerons, but will test it out first in relatively light wind.

Thanks!
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Old 03-31-2015, 12:13 PM
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Thanks for your reply. Yes, I now see how right you are ... I just hope that I'll be able to use it for a small amount of sloping just to try. If it doesn't work out I assume winching is the way to go, but that is a bit of a hassle.

Thanks
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Old 03-31-2015, 11:46 PM
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That nice thermal ship would possibly not gain anything by ailerons. I would leave it as it is. Rather I would install an electric drive, that's appropriate and quite easily done. A small drive with a big prop (on a gear) would be just right and give hours of flight duration.
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Old 04-01-2015, 06:49 AM
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Yes, you're probably correct. That sounds like a good idea - what do you mean by 'on a gear'... Sorry probably a novice question.
Thanks
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Old 04-01-2015, 01:40 PM
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Hi,
If tape, then two layers.
First on is clear high grade that will stay on. Second is a nice tape like colored electrical tape that is applied at the field and taken off after flying. This prevents the covering/paint from lifting.
Also Multiplex and some others have wing locking systems.

Jared
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Old 04-02-2015, 02:17 AM
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Sorry for ambiguity, I simply meant a geared drive. My glider for instance has a 14x9" folding prop spinning at only 5000 rpm. You could use a 17x12" at only 4000 rpm. The quite big pitch is essential for efficiency. For the low rpm you would need such a low Kv motor that it would be far too big (too powerful) for the airplane. I guess you need only 200 Watt in and that means a quite small motor with a gear. Brushless inrunners like a Hacker A30 (or 40 or 50) and a Maxon 4.4:1 gear are customary for such gliders today. There might be cheaper alternatives.
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Old 04-04-2015, 01:29 AM
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Thanks for clarifying that and the detailed information!
I will attach photos when done
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