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Old Apr 03, 2011, 03:48 PM
The Flying Circus
ommadawn's Avatar
Adelaide South Australia
Joined Sep 2007
3,997 Posts
Help!
Folding prop equivalent size

Hi Chaps,
Sorry for the newbie question, but I have fried a few motors in the past,and dont like learning the hard way. I hope to use a motor that is optimised for a 10x5 or 10x6 prop.
http://www.hobbyking.com/hobbyking/s...idProduct=2112
Is it a direct swap to use a same size folding prop, or does the increase in overall diameter from using the folding hub need to be factored in?
Any suggestions on what would be a good folding combo for this motor?

Cheers
Frank
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Old Apr 04, 2011, 09:15 AM
Registered User
Fond du Lac, WI
Joined Mar 2005
559 Posts
As you know the '10' in 10x6 refers to the diameter. It doesn't make any difference whether the blades fold or not, the diameter is still measured the same way: from one tip of the blade to the opposite tip of the blade. For a 10-inch diameter folding prop blade length + hub length + blade length will measure 10 inches. When measuring blade length be sure to measure from the tip of the blade to the center of the hole that the pivot bolt passes through; when measuring the hub length, be sure to measure from the center of the bolt hole on one end of the hub to the center of the blade hole on the other end of the hub.
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Old Apr 04, 2011, 10:01 AM
The Flying Circus
ommadawn's Avatar
Adelaide South Australia
Joined Sep 2007
3,997 Posts
Thanks Bob J,
I kind of suspected that, but just wanted confirmation. I wasnt sure, as there are different manufacturers of hubs and blades. I have a bin with all different sizes of blades and hubs, and tend to mix n match a bit. I guess its probably best to keep to the same make of blades and hubs to maintain the correct rated diameter.
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Old Apr 04, 2011, 12:36 PM
WAA-08 THANK FRANK!
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Las Cruces, New Mexico, United States
Joined Jun 2002
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Get a watt meter.... use the wattt meter....no worries and no guessing needed.
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Old Apr 04, 2011, 01:41 PM
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San Diego area
Joined Jul 2006
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Quote:
Originally Posted by JimNM View Post
Get a watt meter.... use the wattt meter....no worries and no guessing needed.
Hi, Frank:

I agree with JimNM that you need to get a watt meter. It is a real necessity for anyone doing electric powered RC. In addition to watts, it gives you amps, peak watts, peak amps. This can save future fried motors.

I have a Watt's Up brand and really like it. Advantagehobby.com sells it for about $50.

It is absolutely necessary in order to select the best battery/motor/prop/esc combination.

It will give you peace of mind and you will wonder how you ever lived without it.

Craig
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Old Apr 04, 2011, 06:39 PM
The Flying Circus
ommadawn's Avatar
Adelaide South Australia
Joined Sep 2007
3,997 Posts
Thanks for the tips guys. I already use a Watts Up and also a Turnigy IR thermometer.
All of my flying is slope soaring FPV motorgliders. Its a HOOT! (Best viewed in fullscreen)
Greensleeve motorglider at Maslin Beach South Australia (10 min 38 sec)

So my power requirements are a bit different from most electric sailplanes. I just use the motor as my get out of jail card if I wander into a difficult spot and need to cheat to get back.
Cheers
Frank
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Old Apr 05, 2011, 02:21 AM
Multi Rotor Maniac
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Australia, VIC, Melbourne
Joined Oct 2007
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What do the nudists think about an RC plane flying overhead with a camera??? Ive been to Maslins before and it looked like a great place for slope soaring.

I recommend you get yourself a few different sized folding props and test them all out with your wattmeter. That way you can optimise your setup. Dont go buying those cheap HK folding props tho, get yourself some decent graupner or aeronauts as they are far more efficient.
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Old Apr 05, 2011, 09:56 AM
The Flying Circus
ommadawn's Avatar
Adelaide South Australia
Joined Sep 2007
3,997 Posts
At Maslins Beach you do get to see white pointers
Actually I used to fly my hang glider down to Maslins from Ochre Point , about 2 miles N along the coast. I once saw a couple doing the horizontal folk dance up in a secluded gully that was only open to the sky..
Couldnt see anything from 350ft above though.
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Old Apr 05, 2011, 01:53 PM
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San Diego area
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Quote:
Originally Posted by ommadawn View Post
At Maslins Beach you do get to see white pointers
Actually I used to fly my hang glider down to Maslins from Ochre Point , about 2 miles N along the coast. I once saw a couple doing the horizontal folk dance up in a secluded gully that was only open to the sky..
Couldnt see anything from 350ft above though.
I used to fly hang gliders at Torrey Pines.

Same problem, Blacks Beach nude inhabited primarily were gross males, very few women.

But there were some good sights comming off of Ortega Lookout near Lake Elsenor. Lots of sun bathing in back yards.
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Old Apr 05, 2011, 03:26 PM
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Fond du Lac, WI
Joined Mar 2005
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Quote:
Originally Posted by ommadawn View Post
Thanks Bob J,
I kind of suspected that, but just wanted confirmation. I wasnt sure, as there are different manufacturers of hubs and blades. I have a bin with all different sizes of blades and hubs, and tend to mix n match a bit. I guess its probably best to keep to the same make of blades and hubs to maintain the correct rated diameter.
You're welcome

I too have a drawer full of folding prop blades as well as a variety of hubs. I will experiment with different blade and hub combinations to see which works best on a particular model. As has been mentioned by others, a wattmeter is absolutely essential if you don't want to overstress your ESC. I have also found the Castle Creations ICE controllers to be extremely valuable. A wattmeter gives the current under a static condition while the ICE controller gives you a dynamic reading. The dynamic reading is usually somewhat smaller than the static reading with the difference between the two reading varying somewhat from model to model.

Good luck with your project.
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Old Apr 05, 2011, 05:44 PM
Wood Chucker
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USA, TX, Allen
Joined Nov 2009
1,512 Posts
You should be able to get relatively close with a good calculator. This is the same calc that Castle links to for their power estimates.

http://www.ecalc.ch/motorcalc_e.htm


I used that to size my prop and I have no complaints. I'm pulling a 34oz 2M glider with a E-Flite Park 450 and a AeroNaut 11x6 with no problems. I can run the motor for the 30 second motor run and still have all my components cool to the touch. Should provide plenty of margin for the 100F days to come.
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Old Apr 05, 2011, 06:36 PM
The Flying Circus
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Adelaide South Australia
Joined Sep 2007
3,997 Posts
Thanks for the excelllent feedback guys! That calculator is a neat tool. I will be using that heaps. While on the subject, I wonder how the numbers compare from a static motor on the bench compared with a prop that is moving forward through the air at different airspeeds? Would the dynamic flow relative to the blades change the whole performance calculation?
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Old Apr 05, 2011, 06:39 PM
Wood Chucker
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USA, TX, Allen
Joined Nov 2009
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They are apples and oranges. There will be lower blade speeds and higher resistance on the ground. If you're going to be putting a significant number of amps through your ESC you may want to take a look at the Castle ICE series. They have onboard data logging that will tell you all that good stuff through the Castle-Link you need to purchase separately. I wish you could just plug a USB cable straight into the ESC to download data but it is what it is.
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