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Homemade RC Glider

Old 07-23-2019, 09:04 PM
  #51  
quorneng
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aaindthu
You can run the cables through a guide tube but the servo and control horn should still be in the same plane or fairly close to it.
What is important is that when the servo is deflected the tension in the cables should tend to slacken rather than increase..
The trick with pull/pull cables is not to over tension them in the first place as apart from overloading bearings and hinges it will put an additional constant load onto the fuselage.
If you can keep the cables running inside or close to the surface of the fuselage any bending should not be an issue on a plane that is rigid enough to fly!
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Old 08-02-2019, 01:17 AM
  #52  
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the progress so far...

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I did not use the pull pull cable technique because... after 5 crashes in a row, I was hesitant to do
anything that's either complicated or that which is new to me. So I went with what i know - the regular push rods.

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Old 08-02-2019, 02:30 PM
  #53  
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That looks very neat.
I do wonder if you will ever actually need flaps other that to play with to see what happens.

ff I was doing it i would have kept it simple and used just 3 servos (ailerons and elevator) instead of six and put the elevator servo right at the back with a short direct link as you have done for the ailerons.
Such a linkage is significantly more efficient and gives a higher 'precision' than a snake and guess which control needs the greatest precision for accurate flight - the elevator!

As long as you have the CofG more or less in the right place it should fly and I suspect quite well too.
Do let us all know how you get on.
.
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Old 08-02-2019, 02:37 PM
  #54  
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That looks very neat although I doubt you will really need the flaps.

If I was doing it I would have used just 3 servo (ailerons and elevator) rather than 6 and placed the elevator servo right at the back with a short link as you have done for the ailerons.
Such a linkage is both more efficient and gives a greater 'precision' of movement and guess which surface requires the greatest precision for accurate flight - the elevator.

If you get the CofG something like in the right place it should fly and I suspect quite well too.
Do let us all know how you get on.
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Old 08-17-2019, 02:29 PM
  #55  
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My glider is ready to fly.
weighs 907 grams, and C.G is around 20% from L.E.
The 2m Wings are strong enough as seen from the wing load test
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I thought flaps would be useful to land the glider when slope soaring.
I've cut the 11 inch folding prop into a little less than 9 inch one. I've cut it myself with hand, and have no vibration kind of problem.
will fly it soon.

Last edited by aaindthu; 08-17-2019 at 02:52 PM.
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Old 08-17-2019, 03:56 PM
  #56  
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Good load test!
What made you decide to cut down the prop? At 11 inch was it drawing to many amps for the speed controller?
A 11 inch prop cut down to 9 is not quite as efficient as a true 9 if they have the same pitch.
Also a bigger prop run at lower power is significantly better at converting each watt into thrust. Unless you have to go fast big slow props are better.

Last edited by quorneng; 08-19-2019 at 12:05 AM.
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Old 08-17-2019, 06:03 PM
  #57  
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Originally Posted by quorneng View Post
Good load test!
At 11 inch was it drawing to many amps for the speed controller?
.
11 inch prop was creating torque problems for the motor. It was a learning experience for me from my previous glider.
that 11 inch prop made my previous glider to spin out of the sky. so, i cut it down to a 9 inch for my new design.
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Old Yesterday, 01:04 PM
  #58  
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The glider flew alright. But, it was too fast/heavy to be a glider and the wind was only making it worse. And I am a newbie.


I think the airfoil is to blame for its speed. It is a semi symmetric one. Throughout the maiden flight including the glide test, the flaps were down, but still it was flying so fast. It doesn't maintain altitude and likes to dive as seen from the video.

Sooo, I am going to build another wing, but a thicker one with a more slower and lift producing shape of an airfoil. I won"t be adding flaps this time.

I am looking forward to hear the opinions from the experts that you all are!! Thank you.

Last edited by aaindthu; Yesterday at 01:21 PM.
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Old Yesterday, 02:18 PM
  #59  
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Well done!
To me that maiden flight looked fine given it is a home design! Was there much damage?
There are many things you have to get right for a plane to fly well, including the skill of the pilot.
Of course without knowing what control inputs you were making it is difficult to be exactly sure.

My advice is to make any necessary repairs and move the balance point (CofG) forward by say 6 mm (1/4") as it looked to me like it was flying a bit tail heavy, hence the tendency to pitch up a bit on the glide and a lot more when under power.
Remember a nose heavy plane flies well enough but a tail heavy plane flies just once!
Do not use any flaps until you have it flying really well. When used they will effect the way it flies, likely pitch up, leading to a stall and a wing drop into a dive so only test them first time when you have lots of height!
Finally don't worry about it appearing to fly fast. At this stage all you want is it to fly in a controllable manner. It probably will be able to fly quite a bit slower but finding out is for later.
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Old Yesterday, 02:47 PM
  #60  
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Originally Posted by quorneng View Post
Well done!
To me that maiden flight looked fine given it is a home design! Was there much damage?
Quorneng,

Thank you.
Yes, the wing just snapped in two and the slender tail section broke separating the tailplane from the rest of the fuse.

I have changed my plans now, after watching the video again and again. I think I know what is wrong. I think a mere elevator up trim would have prevented this crash.
The glide angle of this glider is not straight with all the control surfaces at neutral position. It tends to glide with its nose pitching down. You can see that during the glide test, just after I launched it (with my right hand), it was pitching down, until I got my hand back on the radio and pulled the elevator up. Only after that, the glider pitches up and there was quite a lot of head wind that might have made it appear as if the glider is tail heavy. But it's definitely not, I am certain.
During the actual flight, again I think the headwind makes it look like its tail heavy.

So, I am just going to give it another try. with some up elevator, after gluing the broken pieces back.
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Old Yesterday, 10:59 PM
  #61  
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Fix it and continue to fly it.

Work on moving that CG around.
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