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Old May 17, 2010, 05:26 PM
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This is perfect! You've made everything so simple! thankyou very much
Thank you very much, Sam!

PS: The reason I made it simple was so that I could understand it myself. I figure if I can understand it, anyone can...

Thanks again for the kind words,

Chuck
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Old May 18, 2010, 08:15 AM
The Flying Circus
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Im not having much luck picking a prop for my motorglider. Its 112"span, 64oz with 803sq inches wing area. I have 3s and 1000kv motor. Direct drive. It currrently spins a 11x8 but I know thats not real efficient. WOC wants me to use a 24" prop but thats just silly on a glider. Any suggestions?
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Old May 18, 2010, 08:20 AM
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Im not having much luck picking a prop for my motorglider. Its 112"span, 64oz with 803sq inches wing area. I have 3s and 1000kv motor. Direct drive. It currrently spins a 11x8 but I know thats not real efficient. WOC wants me to use a 24" prop but thats just silly on a glider. Any suggestions?
Let me take a look at it. Actually, WOC doesn't want you to use a 24" prop. What it always tells you is the most efficient prop, even if it happens to be in a size not suitable for your flying. Obviously, we have to pick a prop from what's available out there, and that often limits our efficiency. I'll be back in a whiole, maybe we can find something better for you...
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Old May 18, 2010, 09:15 PM
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Originally Posted by ommadawn View Post
Im not having much luck picking a prop for my motorglider. Its 112"span, 64oz with 803sq inches wing area. I have 3s and 1000kv motor. Direct drive. It currrently spins a 11x8 but I know thats not real efficient. WOC wants me to use a 24" prop but thats just silly on a glider. Any suggestions?
Can we find out what kind of current your motor is capable of pulling safely, without overheating? Also, do you primarily use the motor to cruise slowly around while you're hunting thermals? Or do you use the motor for climbing hard up to height, then shut it off and glide for long times? Basically, we need to know how you use the motor, and for what.
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Old May 18, 2010, 10:30 PM
The Flying Circus
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The plane is a big floater, and if it goes too fast the wingtips flutter, so I really just want to achieve a climb rate of 150-200 feet/min. Its an FPV camera platform that I usually fly slope and hook thermals from there, so usually the motor doesnt get a run. Its only really there as a rescue option if I get into a difficult position, like low, downwind. I have run the motor comfortably at 15A without overheating. This is it:

http://www.hobbycity.com/hobbycity/s...idProduct=5499
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Old May 19, 2010, 04:52 PM
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That is some really nice work Chuck.

Man, how long did it take you to complete that piece of work?

I ask this because (some years ago) I wrote up a "Choosing an RC Helicopter for Beginners" piece that took quite a bit of time (I think the piece was only 3Kb or so) .
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Old May 19, 2010, 05:01 PM
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That is some really nice work Chuck.

Man, how long did it take you to complete that piece of work?

I ask this because (some years ago) I wrote up a "Choosing an RC Helicopter for Beginners" piece that took quite a bit of time (I think the piece was only 3Kb or so) .
Thank you for the kind words! A lot of the time was spent in putting it in language that a beginner could relate to. Most of the time was spent in getting rid of all the fluff that usually bewilders and confuses newcomers. I just wanted to take away all the hocus-pocus that the pros seem to flood the beginners with, and strip it down to something that made sense on a gut level...

Chuck
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Old May 19, 2010, 05:20 PM
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Originally Posted by NoFlyZone View Post
Thank you for the kind words! A lot of the time was spent in putting it in language that a beginner could relate to. Most of the time was spent in getting rid of all the fluff that usually bewilders and confuses newcomers. I just wanted to take away all the hocus-pocus that the pros seem to flood the beginners with, and strip it down to something that made sense on a gut level...

Chuck
You're dead on Chuck.

The first thing that any technical writer must address is just who his or her audience will be.
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Old May 20, 2010, 10:07 AM
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Wow, I've been looking for something like this for the 5 years that I've been into electric flight. It really takes away the trial and error. Thank you Chuck.
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Old May 20, 2010, 10:10 AM
Tom Bass Park RC Nonconformist
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Subscribed!!
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Old May 20, 2010, 12:20 PM
2 no or knot 2 no!
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Too cool, thanks so much for sharing your knowledge.
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Old May 20, 2010, 01:16 PM
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Too cool, thanks so much for sharing your knowledge.
Thank you! One of my mentors wrote WebOCalc, and my only contribution is to break down to the simplest elements the things that all of us hobbyists need to know in order to make wise decisions, and to apply the basics to his wonderful program. Believe it or not, it doesn't have to be any more complicated than what is presented. I love it when I know the 'whys' behind things we do in RC. I love it even more when I don't have to rely on other people's choices for what would work best in my planes.

If I can help (in my limited way) in any way possible, I certainly will.

Chuck
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Old May 20, 2010, 01:17 PM
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Wow, I've been looking for something like this for the 5 years that I've been into electric flight. It really takes away the trial and error. Thank you Chuck.
Believe me, it is truly my pleasure!
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Old May 20, 2010, 05:45 PM
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OK, time for a practice exercise ...

I'm about ready (literally) to go fly my plane. and for the life of me, I can't remember which prop it uses because I took the prop off to store it last year, and I have the attention span of a doorknob.

Here's the specs:

11.7 ounces AUW
Wingspan 35"
Wing Area 300 inē
I can use any size prop I want and have tons of ground clearance.
I'd like "Gentle scale flight" as my flight mission.
I'm using a 4100 kV motor, and a 6.66:1 gearbox. The motor would be classed as an "Average Inrunner".
I'd like to use my 2s Li-Pos in it.

What prop shall I stick on it, and how much current will I be using, and what's my expected top speed and thrust?

EDIT: By the way, the reason I picked this problem is because once we see what prop I'm using, we are going to lay to waste that old adage about needing 'so many watts per pound' to fly our planes in such and such a manner. That old adage is pure, unadulterated cockapoo!
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Last edited by NoFlyZone; May 20, 2010 at 06:24 PM.
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Old May 21, 2010, 02:25 AM
The Flying Circus
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Oh Man, I wasnt expecting homework!!
Are we going to be tested on this?
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