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Homemade RC Glider

Old 05-11-2019, 07:51 AM
  #1  
aaindthu
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Default Homemade RC Glider

Hello,

I wanted to do slope soaring so badly and I have finally found a place in Chennai to do slope soaring, but the hill was too rugged and covered with thick vegetation. I had a motorless Flying wing glider and I was afraid I would lose the model somewhere among these bushes and I Never did slope soaring before. So I am going to build a motor glider. This time with some good quality materials and extra functions like spoilers etc. So I thought I'll start a build log (again), if that's okay.
Here's the basic sketch of the glider
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I have decided to start with wings. It's going to be 2 meter long and made of foam, supported by 4mm thick plywood spars.
I have done the frame work on the wings.
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The in-between spaces will be glued with High density foam and the space at the centre of the frame is for the fuselage.
The two short square-beams at the centre will be glued to the fuselage permanently and wings should slide in and out for easy transport. No rubber-bands this time.
Click image for larger version

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The frame weighs 240 grams without the square beams. Seems light enough to me, for a 2 meter wing. Or, should I be concerned?
Please tell me what you think.
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Old 05-11-2019, 08:21 PM
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quorneng
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aaindthu
The nearest 2m solid foam wing powered glider I have is an ST330.
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The wings including a pair of aileron servos and an aluminium joining tube weigh 340 g.
At 240 g for your basic structure I think your complete wing is likely to end up a bit heavier.
Extra weight for a slope soarer is not too much of a problem except more weight means it will fly that bit faster and will need more wind up the slope to keep aloft.
For faster flying your wing section does look to be on the thick side.
To give an example the wing of the ST 330 is 220 mm front to back and is 24 mm thick.

I will follow your blog with interest.
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Old 05-12-2019, 02:16 AM
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aaindthu
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Quorneng,
That was valuable information, some number for reference-exactly what I wanted. Thank you very much.
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Old 05-13-2019, 02:27 AM
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The wings ended up being too heavy. I am going to replace the wooden beams with aluminium wire from cloth hanger and cut off half the length of the frame on each side of the wing.
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Old 05-13-2019, 07:39 AM
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Wildflyer
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Check plans available at, Aerofred.com and outerzone.com
You can download the PDF's for free for many, many model aircraft, including gliders with proven designs
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Old 05-13-2019, 12:49 PM
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aaindthu
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Wildflyer,

Thanks for the links.
But, in a way, I think my design is also a proven design. Because, it is simple, conventional and
there are many similar gliders out there.
It's the same fuselage, wing and V-tail (also very conventional).
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Old 05-19-2019, 01:57 AM
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The wings ended up weighing 400grams. But I got another idea to make it even lighter.
so I am going to build the wings for the third time.
This time without the plywood.
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Old Yesterday, 12:24 AM
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AEAJR
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I have done a LOT of slope soaring. Weight is often not a big issue for slope gliders. All depends on the height of the hill and how strong the wind might be. I have seen slope gliders made out of solid maple wood.

I have taped a 16" spike onto my ZAGI foam slope wing for ballast.

EPP foam is popular for slope gliders as it is almost indestructible.

So, tell us about your hill, the height of the hill and typical wind speed.
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Old Yesterday, 05:22 AM
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aaindthu
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AEAJR,
Hi,

The wind at my place is not strong at all. It's moderate breeze at maximum and at times it drops to zero wind for 5 seconds or so. The thick vegetation obstructs the wind speed further.

I don't know how to measure the height of the hill. But you can have a look at it in google maps 3d view. here's the link https://www.google.co.in/maps/place/12%C2%B057'19.4%22N+80%C2%B004'25.1%22E/@12.9630339,80.070029,203a,35y,142.87h,79.02t/data=!3m1!1e3!4m9!1m3!11m2!2sVaUz2PnZz8Utim3t-5qpy7FvTod16A!3e1!3m4!1s0x0:0x0!8m2!3d12.95538!4d8 0.073626?hl=en

Because the wind speed is gentle to moderate, I am trying to keep the weight as low as possible.
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Old Yesterday, 11:18 AM
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quorneng
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aaindthu
With that sort of location I think you are quite correct to keep the weight, and thus the flying speed, as low as you can, particularly as that type of "mound".hill will not produce the strongest lift for any given wind speed.
What is required for slope soaring is that when your glider is flying a bit faster than the wind speed going up the slope it is gliding at an angle a bit less than the angle of the slope.
To do this needs a suitable combination of flying speed and aerodynamic efficiency. The slower the wind speed and the more gentle the slope the harder it gets to find a workable combination.
Without previous experience simply do the best you can and have a go.

Just a point but have you ever seen anyone else flying gliders at that location?
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Old Yesterday, 03:21 PM
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AEAJR
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Build it light but make a provision for adding ballast for those days when the wind is stronger and the lift is strong.
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Old Today, 12:26 AM
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aaindthu
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Originally Posted by quorneng View Post
Just a point but have you ever seen anyone else flying gliders at that location?
No, I've never seen anyone else doing anything
At all at that location. Thank you very much.
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Old Today, 02:16 PM
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aaindthu
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Wings are almost done.
Servos are not yet installed. And then I will put some tape on it for strength.
As of now, the wing weighs only 212 grams. including the aluminium wires from cloth hanger.
I am expecting the total weight to come around 300 grams. Will post pics soon.
​​​​​
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Old Today, 04:39 PM
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I look forward to some pictures.
If you really do achieve 300 g for a 2 m span wing it will indeed be pretty light.
I hope it proves strong enough to survive more than one flight! .
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