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Feb 15, 2013, 10:07 PM
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CoolCanuck's Avatar
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Looking for a 12.5x4 folding prop


Anyone knows who makes a 12.5x4 folding prop?
Looking to install on my 2m Simprop Excel Competition (first series fiberglass fuselage, with built-up wing), using a C3542/06 KV100 // SK3536/05 KV1400 or SK3548/03 KV1100), on 3 / 2 or 5 cells respectively.
My calcs show that this would make interesting combinations ...

I thought there was a CAM one available, but can't seem to find one.
Last edited by CoolCanuck; Feb 15, 2013 at 10:13 PM.
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Feb 16, 2013, 01:26 AM
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CoolCanuck's Avatar
Thanks Rick. Aware of those.
I already have an Aeronaut 12.5x6, hence looking for the 4"pitch.
Feb 16, 2013, 04:14 AM
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WimH's Avatar
The white Aeronaut 12* 7 folder has a real life pitch much closer to 5 than 7 and may be exactly what you're after. You could use a twisted aeronaut yoke to fine-tune it even further , here's a list with measured values for the black/carbon props...(in cm ....)
http://www.aero-naut.de/fileadmin/do...eichswerte.xls
Feb 16, 2013, 02:10 PM
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CoolCanuck's Avatar
Thanks Wim. I'll have to investigate this a bit further and educate myself. Never considered offset yokes before.
Feb 16, 2013, 04:33 PM
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sneu's Avatar
There is a good reason why they don't make many props like a 12.5x4---they are best suited for applying epoxy than to spinning on the nose of your plane. Anything below a .5 pitch-diameter ratio is not good for things that fly. Props like that will give lots of static thrust but once the plane is moving things go bad. Better to get a smaller diameter prop with more pitch. As a general rule you want a PD of .75 or more.

Steve Neu


Steve
Feb 16, 2013, 09:14 PM
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vil64's Avatar
Hey guys, this is what I'm looking for. I've got 2m moldie and would like to use Neu 1110/1y/6.7 motor. Can somebody tell me what would be the smallest folder you can run on this with high pitch for speed.
Feb 17, 2013, 12:57 AM
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Quote:
Originally Posted by sneu View Post
There is a good reason why they don't make many props like a 12.5x4---they are best suited for applying epoxy than to spinning on the nose of your plane. Anything below a .5 pitch-diameter ratio is not good for things that fly. Props like that will give lots of static thrust but once the plane is moving things go bad. Better to get a smaller diameter prop with more pitch. As a general rule you want a PD of .75 or more.

Steve Neu


Steve
Not valid for all cases.
In multicopters the lowest PD possible is the most sought. 12x3.8 is the most obvious example that comes now, but also 17x5 are available.
Yes, this application field means lots of static thrust, and (apparently) zero speed.
But I think it is valid for gliders propulsion too. I climb better with a 13x5 than with a 12x6.5, same MVVS 960kv motor.
Feb 17, 2013, 12:29 PM
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sneu's Avatar
Quote:
Originally Posted by renatoa View Post
Not valid for all cases.
In multicopters the lowest PD possible is the most sought. 12x3.8 is the most obvious example that comes now, but also 17x5 are available.
Yes, this application field means lots of static thrust, and (apparently) zero speed.
But I think it is valid for gliders propulsion too. I climb better with a 13x5 than with a 12x6.5, same MVVS 960kv motor.
A PD prop is like a plane stuck in 1st gear--lots of pull at the start but is quickly hits the wall and stops accelerating. The one place low PD makes sense is for static operation--like the quad copters but gliders are better with higher PD props.

Steve Neu
Feb 17, 2013, 12:30 PM
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sneu's Avatar
Quote:
Originally Posted by vil64 View Post
Hey guys, this is what I'm looking for. I've got 2m moldie and would like to use Neu 1110/1y/6.7 motor. Can somebody tell me what would be the smallest folder you can run on this with high pitch for speed.
How many cells?
Feb 18, 2013, 03:09 AM
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vil64's Avatar
Planning 3cell 2200mAh
Feb 18, 2013, 07:54 AM
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sneu's Avatar
Quote:
Originally Posted by vil64 View Post
Planning 3cell 2200mAh
There are F5D pylon props that are 11x22 that would give you around 140mph prop pitch speed. http://www.neumotors.com/store/page11/index.html

If those are over the top then I would be looking at a 12.5x13 of 15x16 from SUSA http://www.soaringusa.com/Props/?page=11

Steve Neu
Feb 19, 2013, 03:43 AM
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vil64's Avatar
Thanks Steve, that's the info I was looking for.
Mar 11, 2013, 05:31 AM
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vil64's Avatar
Hi Steve, I have just changed my mind and plan to use Neu 1105/2.4y/4.4:1 instead of 1110/1y/6.7. Still, I will use 2200mAh 3S. Could you please let me know what could be the smallest folding prop I can use for speed. This is going to a 2m Spirit E glider/hotliner.
Mar 11, 2013, 09:41 PM
Balsa addiction since age 3
ScottSails's Avatar
Quote:
Originally Posted by sneu View Post
A PD prop is like a plane stuck in 1st gear--lots of pull at the start but is quickly hits the wall and stops accelerating. The one place low PD makes sense is for static operation--like the quad copters but gliders are better with higher PD props.

Steve Neu
Awesome analogy.... I think this is a great way to describe it.


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