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Attaching a 10mm prop to a 8mm motor shaft.

Old 11-25-2012, 10:16 AM
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Dayaks
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Default Attaching a 10mm prop to a 8mm motor shaft.

Hello,

I bought a Neumotor 1924 and most props (like a Xoar PJA prop) I am interested in are 10mm. I am at a bit of a loss of how I safely connect the prop to the motor in a way I don't get myself killed. Any suggestions? I've been looking around and it's difficult to find guides on a motor of this power. (I've used a collet on smaller motors.)

Thanks.
Old 11-25-2012, 10:26 AM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

I think you are in need of a prop reamer to open the shaft hole. Tower sells them in both metric and SAE. Most hobby shops stock them. They are just step reamers and you do it by hand, they have a handle on them. Some people remove the4 handle and use them in a drill press. It's worth buying both of them to keep in your flight box.
Old 11-25-2012, 11:57 AM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

Most of the 8mm prop adapters I've seen are for 10 mm props. Can you use something like this? https://www.leaderhobby.com/product....=9394001130003
Old 11-25-2012, 12:05 PM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

It sounds like you are trying to mount a gasser prop to an electric. If so, bad idea. The gasser prop will draw much more current. For E setups you MUST use an E prop for best performance. APC has a huge line of E props up to at least 22" Zoar makes wood E props that should have the 8mm hole. All the larger APC props come with an 8mm hole as well
Old 11-25-2012, 12:25 PM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

Hmm, does the Neumotor 1924 have a 10 mm shaft or is it 8mm as the title suggests?
Old 11-25-2012, 01:26 PM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

Confused me, I thought he just needed to open an 8 to a 10. If it's the other way around then a shim will work. I have a number of prop shims for electrics.
Old 11-25-2012, 01:33 PM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

Gray, I hear ya but when electrics get this big the difference between an E prop and a gasser prop mean alot more current. The gasser prop is simply too heavy and the blades are too thick. He could easily fry the motor/controller.
Old 11-25-2012, 05:09 PM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

I think I found a collet that adapts to 8mm motor shaft and uses 3/8" (approx 10mm) props on tower hobbies. I plan to get around a 22" prop and meter/TC the setup in a fixture. In my eyes collets are extremely easy to use and this reduce the risk of something bad happening. My main concern was if there's a power limit to collets. I guess a lot of the props I was looking at were 10mm or a choice between 8 and 10.

The collet I found: http://www3.towerhobbies.com/cgi-bin...&I=LXMWL0&P=ML

Edit: I may have been looking at a few gassers by accident too. I guess I should look into a way to mount 8mm to 8mm... 8 to 10 would still be fine for Mejzlik. Or if I bored out other props like mentioned above.

Thanks for the replies. Even if I confused you I have a better understanding now. I'll also try and make sure I get electric props.
Old 11-25-2012, 06:04 PM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

Neu has an 8mm shaft, but you need to use a prop adapter. There are some 8mm/8mm prop adapters, but really you're better off using an 8mm/10mm adapter as it will be more robust (I have used both quite a lot). You can use the GP 3/8" adapter you linked (I have a few) or you can get some of these below:

http://www.espritmodel.com/prop-shaft-adapters.aspx
Old 11-25-2012, 06:07 PM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

You are using a big prop on a powerful motor, I think you will not regret using the NEU prop adapters, they are very robust and can handle those props at that power with no problem:
http://www.f3aunlimited.com/webstore...products_id=45

I understand the cost is a lot more (relatively) than the Great Planes or Esprit adapters, but this is a very good design that is used extensively on high power Neu and Hacker setups. You might cringe when you pay for it, but never again.
Old 11-25-2012, 06:10 PM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

Please let us know how your project works out! I have been interested in those motors but didn't want to be the 'guinea pig' - they supposedly have their efficiency curve geared toward large props (helis actually) but with your 22" prop you might be getting close. I am curious what battery configuration you use, and what the readings look like on your meter
Old 11-25-2012, 07:17 PM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

I'll definitely post the results! I'll take a look at the Neu prop adapters. Thanks for the heads up.

I picked that motor since it had decently high watt ratings and some low KV ratings. It's also cheap (relatively to Neu's other motors) so if I have a whoopsie it's not as painful. I plan to run it on a CC Ice2 HV 160 controller with 12S. I did not plan to start this project for another six months but CC had a Black Friday deal with $120 off the hv160. I couldn't resist.
Old 11-25-2012, 07:31 PM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

What airplane?
Old 11-25-2012, 07:36 PM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

ORIGINAL: speedracerntrixie
The gasser prop will draw much more current. For E setups you MUST use an E prop for best performance.
I would argue against this point for these larger propellers. APC (and most other) props flex. They have redesigned their larger props to flex less, but the still do. There is a big gain to switching to something like a carbon fiber prop. I have a friend who has done some testing (including working with APC) and found that glow props are more efficient than the electric props at large sizes and high power. I would take a wooden glow prop over an electric APC prop. The Xoar he's using might even be lighter too, but that is a guess.
Old 11-25-2012, 08:39 PM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

Joe, take a look at the prop that he mentions and then realize that it comes with a 10mm center hole.

http://www.xoarintl.com/props/model-airplane/PJA.html

The reason that it comes with a 10mm center hole is that is the standard dia. on all gasoline engines, not glow. The prop he is looking at is intended for gasoline/ignition engine with a 4 or 6 bolt hub. As a result the hub and blades are thicker to take the stress of this type of engine. I'm not 100% sure but it sounds like we are talking 22" to 24". Now take a look at what Xoar makes speciffically for electric in those sizes.

http://www.xoarintl.com/props/model-airplane/PJH-E.html

there is a big difference, I still would not run a gasser prop on an electric setup, it is going to draw more current. Yes the APCprops do flex however if you look at whats on the nose of 75% of 2M pattern airplanes you will see APC E props. The others will be mostly Falcon CF E props.
Old 11-25-2012, 09:42 PM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

I'm not saying that gas prop is ideal, but it is not going to hurt anything to try it. The best prop is what feels the best to the pilot. Hopefully he will try a few.

The 10mm hole is perfect for the right prop adapter (which has a 3/8" or 10mm prop shaft).

Now that there are a few brands of carbon props, guys are switching away from APC at a decent rate. Falcon, PT, Rasa, and Mejzlik are all making carbon prop sizes suited for pattern. And I think almost everyone would switch if it wasn't about cost. APC has a great aerodynamic design. A few of those carbon prop companies copy the design. The benefit to composite props (APC, carbon, etc) is that you can design the prop with sharp edges and still maintain strength. I believe the more blunt edges of a wood prop are the reason you don't see wood props in pattern; they sacrifice aerodynamic for mechanical design, thus affecting performance. I think Hatta came out with a wood prop for pattern but it's laminated with glass and is super wide.

I have a few Xoar e-props. They are OK, they don't pull a lot of current but they also don't seem to produce as much thrust. I will not buy them again. I would personally still try a gas prop to see the difference. I would bet on better throttle response and thrust, and possibly LESS amps. Flexing propellers is wasting a bunch of energy. Dave L has run some glow props on his Neu inrunner and found the glow props were more efficient than electric props. It might depend on flying style, it's hard to say where one would draw the line between the extra energy needed to spin a heavier prop and the energy lost due to flex. The prop flexes every time you touch the throttle, so that's a lot of loss.

Don't forget the motor he is using is designed for direct drive helicopter applications, so swinging a big/heavy prop is it's purpose. I say try it, worst thing that happens is he doesn't like the performance or efficiency.
Old 11-25-2012, 11:53 PM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

Setting up for a big electric isn't as easy as some make it sound.
First, you shouldn't start with a prop near the max limit unless it's been tried and found to work reliably with that particular motor/ESC/battery setup. If unsure, then it's best to 'back into' which prop to use by trying one that's undersize at least an inch or two, checking the RPM vs. amp load and temp of components at WOT. I know it's not the most economical way, but is better than frying a motor or ESC the first time out. Been there, with the T-shirt. [X(]
Another important consideration is not running the prop above its rev limit, remembering you'll gain 10%+ RPM in the air as the prop unloads. Last, I don't know why anyone would run a gasser prop in an E application. The E prop is lighter to take acceleration loads off the motor, which means less heat, mechanical stress, etc. There is an E prop, or 3, out there that will be perfect for your application.

Xoar E props:
http://www.xoarintl.com/rc-propellers/electric-props/PJN-Electric-Beechwood-Propeller/
Old 11-26-2012, 05:18 AM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

A simple fix to a simple question.I have used heatshrink tubing,1 to 4 peices depending on how much shim was needed.use very little heat just enough to make it stay in place,they come in alot of sizes for a build up to what you need.just a thought.
Old 11-26-2012, 06:34 AM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.


ORIGINAL: eddieC

Setting up for a big electric isn't as easy as some make it sound.
First, you shouldn't start with a prop near the max limit unless it's been tried and found to work reliably with that particular motor/ESC/battery setup. If unsure, then it's best to 'back into' which prop to use by trying one that's undersize at least an inch or two, checking the RPM vs. amp load and temp of components at WOT. I know it's not the most economical way, but is better than frying a motor or ESC the first time out. Been there, with the T-shirt. [X(]
Another important consideration is not running the prop above its rev limit, remembering you'll gain 10%+ RPM in the air as the prop unloads. Last, I don't know why anyone would run a gasser prop in an E application. The E prop is lighter to take acceleration loads off the motor, which means less heat, mechanical stress, etc. There is an E prop, or 3, out there that will be perfect for your application.

Xoar E props:
http://www.xoarintl.com/rc-propellers/electric-props/PJN-Electric-Beechwood-Propeller/
+1

The PJN is a much better prop for your application. I have them for a 60 size electric motor that had a 10mm shaft and had to open up the 8mm hole but yours should fit just fine as is.
Old 11-26-2012, 04:57 PM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.

I'd go to your LHS and see if they have what you need,most of the RC hobby stores carry all that stuff.
Old 01-10-2013, 12:31 PM
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Default RE: Attaching a 10mm prop to a 8mm motor shaft.


ORIGINAL: speedracerntrixie

Joe, take a look at the prop that he mentions and then realize that it comes with a 10mm center hole.

http://www.xoarintl.com/props/model-airplane/PJA.html

The reason that it comes with a 10mm center hole is that is the standard dia. on all gasoline engines, not glow. The prop he is looking at is intended for gasoline/ignition engine with a 4 or 6 bolt hub. As a result the hub and blades are thicker to take the stress of this type of engine. I'm not 100% sure but it sounds like we are talking 22" to 24". Now take a look at what Xoar makes speciffically for electric in those sizes.

http://www.xoarintl.com/props/model-airplane/PJH-E.html

there is a big difference, I still would not run a gasser prop on an electric setup, it is going to draw more current. Yes the APCprops do flex however if you look at whats on the nose of 75% of 2M pattern airplanes you will see APC E props. The others will be mostly Falcon CF E props.
I have the same problem I got a xoar prop with a 10mm home and the OS gt33 gas motor I just got has a 8mm shaft and the OS gt33 is a single hole hub

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