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« on: May 22, 2014, 09:59:32 PM »
K K Iyer
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@anwar sir,
It seems to me that a majority of posts are commercial in nature - 'I want this, I want that'
While this has a rightful place, and RCI provides a suitable forum,
I wonder if we could have a board for purely technical discussions.
For example, I would like to exchange notes with someone who has done some experimenting with L/D ratio of say AG03 aerofoil.
Can we have a board like Tech Notes, or Tech Corner?
Don't know if there will be adequate response, but what's the harm in trying?
Regards.
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« Reply #1 on: May 22, 2014, 10:28:25 PM »
K K Iyer
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For example,
Here is something bothering me for the last two weeks.
If you've seen the test hand launch of my RCTLG, you would have noticed that it went over 60m from a sub 2m launch.
From the video and google earth, i calculated that the avg speed was about 8m/s.
For the 200gms wt, that requires a Coefficient of lift of just under 0.5.
For the 4" avg chord, at 8m/s, the Reynolds number is around 50k.
The polar at Re 50k for the AG03 aerofoil I used shows that the L/D at CL=0.5 is about 25.
That is for the wing alone, not accounting for the drag of the fuselage and empennage.

The question therefore is:
How could the test flight achieve L/D of over 30?

Grateful for expert comments please.
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« Reply #2 on: May 22, 2014, 10:49:01 PM »
utkarshg13
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I totally agree with Iyer Sir. These days only for sale/wanted threads are being updated. As soon as my exams would get over I'll post a thread regarding FHSS(Frequency Hopping Spread Spectrum).
Sir, you can use xflr5 or profili. Or even the trial version of design foil. Might be it is of some help.

 Hats Off
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« Reply #3 on: May 22, 2014, 11:06:18 PM »
K K Iyer
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@utkarshg13
Remember to post only original stuff from your own exprience/experiments.
Not copy paste, as we can find such stuff on the internet ourselves.
Pl see my pm.
Regards.
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« Reply #4 on: May 22, 2014, 11:16:11 PM »
utkarshg13
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Sir, I'd personally not used these softwares. But, once my friend at IIT-K had shown me. So, I thought it might of some help to you.
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« Reply #5 on: May 23, 2014, 04:02:24 PM »
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+1 to having a Tech Board
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« Reply #6 on: May 23, 2014, 11:50:43 PM »
K K Iyer
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@rcpilotacro
Been wondering where you were!
My query (pl see reply #1)
How could the test flight achieve L/D of over 30?
relates to this test flight

My own guess is that the answer lies in excess kinetic energy at launch.
Should i cut the video to pieces and assess the velocity in each 1 sec segment?
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