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Old Aug 07, 2009, 06:35 PM
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antonlubo's Avatar
East SF bay
Joined Apr 2007
572 Posts
Prop weights

Hi all,
With nothing better to do, I weighed some props. The EPP 10x4.5 comes in at 6 g the 12x4.5 is 10g. The APC 10x4.7 is 11g and the 12x3.8 is 19g. This can be filed as you wish...Tony
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Old Aug 07, 2009, 07:33 PM
. . . gravity?
Flyboy_001's Avatar
Huntsville, Alabama
Joined Mar 2008
542 Posts
Thanks Tony!
I know this has come up several times on a couple of threads, it helps to have it all sitting side by side.
Greg

Quote:
Originally Posted by antonlubo
Hi all,
With nothing better to do, I weighed some props. The EPP 10x4.5 comes in at 6 g the 12x4.5 is 10g. The APC 10x4.7 is 11g and the 12x3.8 is 19g. This can be filed as you wish...Tony
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Old Aug 07, 2009, 08:30 PM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
14,705 Posts
Thanks Tony.
Does anyone successfully use the APC 10x3.8 pairs that are also available? If so, then with what motors?
Cheers,
Jim
Quote:
Originally Posted by antonlubo
Hi all,
With nothing better to do, I weighed some props. The EPP 10x4.5 comes in at 6 g the 12x4.5 is 10g. The APC 10x4.7 is 11g and the 12x3.8 is 19g. This can be filed as you wish...Tony
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Last edited by jesolins; Aug 08, 2009 at 06:40 AM.
Old Aug 07, 2009, 09:20 PM
Registered User
antonlubo's Avatar
East SF bay
Joined Apr 2007
572 Posts
Quote:
Originally Posted by jesolins
Thanks Tony.
Does anyone successfull use the APC 10x3.8 pairs that are also available? If so, then with what motors?
Cheers,
Jim
Hi Jim,
Just got the props and haven't flown with them, yet. Just tested one a little and got, for the APC 10x4.7 a little over 710 grams of thrust at 13.5 amps on an AXI 2217/20...Tony P.S.. This might be off a little, my test equipment is not the best

Corrected prop size. Sorry, Jim, thought I had the 3.8
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Last edited by antonlubo; Aug 07, 2009 at 09:47 PM.
Old Aug 07, 2009, 10:18 PM
13brv3's Avatar
Navarre, FL
Joined Mar 2002
3,845 Posts
Quote:
Originally Posted by jesolins
Thanks Tony.
Does anyone successfull use the APC 10x3.8 pairs that are also available? If so, then with what motors?
Cheers,
Jim
Hi Jim,

Just the other day, I tested an APC 10x3.8, 10x4.7, and EPP1045 on the Turnigy 2213/22 motor. The 3 are virtually identical in thrust.

EPP 1045- 29.2 oz
APC 10x3.8SF- 29.1 oz
APC 10x4.7SF- 29.7 oz

I just received some APC 12x3.8SF props today, but haven't tested them on this motor. Previously, I've tested them on a DT750, and they were right up there with the EPP1245 for thrust. Of course, the APCs coast forever, and clearly aren't going to be the best for instantaneous speed changes.

The 10" props I have are a bit different between the 3.8 and 4.7 pitch. Mostly, the hub of the 3.8 is much thicker, and I'd bet the whole prop is slightly heavier than the 4.7. I'm not sure if that's just a difference between the batches, or if they're all that way. The 12x3.8 props are closer to the 3.8's in thickness.

I balanced the 10x4.7 set as best I could, and made a flight in perfect conditions. I may very well have been the best MK flight I've ever had, BUT this was no wind, and only one flight, so don't read much into this yet.

Rusty

PS- I only used one locknut, with no tiewraps or o-rings
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Old Aug 08, 2009, 05:38 AM
Registered User
Hoofddorp, Netherlands
Joined Sep 2004
3,917 Posts
Quote:
Originally Posted by martinch
@Arthur P
I've tested a few motors, but the turnigy was the worst of all...
I think the Roxxy and Axi Motors are better ones.
Axi's are undoubtedly better quality which is reflected in their price. The Roxxy' do not have a very good reputation. Many of the original Roxxy's had internal shorts. And most are lower power than the 2217's. The KDA's I-ve seen were qualitatively significantly worse than any of the Turnigy's I-ve seen so far. The TowerPro's vary being somewhere between the KDA's and the Turnigy's.

So far I-ve only had one single Turnigy on which the prop adapter would not center correctly. As indicated this was simply remidied and after scraping a way a bit of metal sticking up from a screw hole the adapter does center correctly. The 2217/20's are probably not the most efficient of the motors in their class, but overall I-ve found their quality to be OK. They've done well for the last almost 2 years. The current vibration problems are certanly multifactorial and not just related to these motors or props. On the ground or in a hover under calm conditions they don't show up which you would expect if these were simple motor/prop-induced vibrations.

As indicated the vibrations hit when the craft hits layers of air with higher wind speeds in calm conditions, or is flown in higher wind conditions. Under those conditions there could be more revving of the motors, and possibly more bouncing around which could induce vibrations in the motor mounts, arms, frame, etc. Not sure whether there might be an effect of higher wind speeds over the plane of the props.

Have just stiffened the 4mm thick motor mounts as they did allow a little bit of flex. This could be a factor if the motors start revving up and down at high frequency. Arms are already stiffened with 8mm carbon tubes glued into the 10mm alu arms. Frame might be stiffened a little bit more, but is already of such stiffnes that I really wouldn't expect that to contribute much to the problem.
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Old Aug 08, 2009, 05:51 AM
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Old Man Mike's Avatar
Joined Oct 2007
1,803 Posts
Vibration Reduction By Prop Rotation

I think those of you trying to reduce quad vibration to obtain good video and still picture performance will be interested in a series of tests I just completed. Using the vibration analysis of the motor/prop test fixture (discussed in this thread: Motor/Prop Test Fixture), the prop was rotated in one of 8 positions to find the point of lowest vibration. The recorded positions are shown here:





Five different motors and five different props were used during the test. Before installation on the motors, all props were balanced using a magnetic balancer by adding a small amount of tape on the under side of the prop blade. The props were then mounted on the motors.

The motor/prop test fixture was used to measure the percent of vibration for different offsets positions of the prop. In all cases a minimum of 1% or less was achieved. The data collected using the minimum vibration position as a reference shows a very interesting result:





This chart shows that even with balanced props, there is a sweet spot for mounting that will provide a minimum vibration level. Without testing, it is very unlikely that a low vibration will be achieved and most likely the number will be at least two times greater than the minimum. It could even be much worse. One of the five motor/prop combination had more than 6 times times the minimum vibration for some prop positions and more than 4 times as much even just 45 degrees away from the minimum position!

It typically takes about 10 mins per motor/prop to find the minimum so it adds a bit of time to my quad builds. Since I'm somewhat obsessed with getting low vibration performance with my quads, I think it is worth the effort.

OMM
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Old Aug 08, 2009, 06:52 AM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
14,705 Posts
Thanks Rusty and Mike for the great prop info.
I am starting to realize, what Arthur P. obviously did long ago, that the EPP1045's are just an accident waiting to happen with their habits of random breaking despite best practices of balancing, mounting and even replacement after hard landings, particularly with quads above 1kg. The bigger they are the harder they fall so to speak. If the performance trade-off for an AVP platform is not that great using APC's which seem not to break in-flight, then the answer to get rid of that hazard is obvious.
So you are back to using a nut on your props, eh?...
Cheers,
Jim
Quote:
Originally Posted by 13brv3
Hi Jim,
Just the other day, I tested an APC 10x3.8, 10x4.7, and EPP1045 on the Turnigy 2213/22 motor. The 3 are virtually identical in thrust.
EPP 1045- 29.2 oz
APC 10x3.8SF- 29.1 oz
APC 10x4.7SF- 29.7 oz
I just received some APC 12x3.8SF props today, but haven't tested them on this motor. Previously, I've tested them on a DT750, and they were right up there with the EPP1245 for thrust. Of course, the APCs coast forever, and clearly aren't going to be the best for instantaneous speed changes.
The 10" props I have are a bit different between the 3.8 and 4.7 pitch. Mostly, the hub of the 3.8 is much thicker, and I'd bet the whole prop is slightly heavier than the 4.7. I'm not sure if that's just a difference between the batches, or if they're all that way. The 12x3.8 props are closer to the 3.8's in thickness.
I balanced the 10x4.7 set as best I could, and made a flight in perfect conditions. I may very well have been the best MK flight I've ever had, BUT this was no wind, and only one flight, so don't read much into this yet.
Rusty
PS- I only used one locknut, with no tiewraps or o-rings
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Old Aug 08, 2009, 09:45 AM
The tattoo guy
Greasetattoo's Avatar
USA, MN, St Paul
Joined Jun 2009
614 Posts
Hey Everyone,

I was wondering if anyone else was having this problem..

I was out in the field the other day flying and I got totally confused on my Mikrokopter.
I could not tell if it was flying towards me or away from me.
Almost seemed like a optical illusion?

I don't know if the copter was to far away or it was just me?

I actually came in to fast and hit the ground.
Broke a aluminum arm.
Being fixed as we speak.

I do have orange leds on the front and my front aluminum arm is painted fluorescent, with a fluorescent ping pong ball on the front.

Maybe inexperience?
This was about my 5th flight with the kopter.

I did fly the Draganflyer before this, though.
Mikrokopter is much faster!

Thanks
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Old Aug 08, 2009, 09:49 AM
Tinkering again!
MorenoEnNYC1's Avatar
New York, U.S.A.
Joined Aug 2007
1,367 Posts
For an AP platform I personally feel you don't need/want precise on the dime performance such as you would for sport flying. For an AP platform you want smooth gradual response...especially for video I've used the Axi/APC combo from day one using only a lock nut (no zips or savers) without fail.

AJ

Quote:
Originally Posted by jesolins
If the performance trade-off for an AVP platform is not that great using APC's
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Old Aug 08, 2009, 09:53 AM
Tinkering again!
MorenoEnNYC1's Avatar
New York, U.S.A.
Joined Aug 2007
1,367 Posts
Do you have any visible markers on the rear/left/right arms of your MK that is easily seen when your craft is at eye level? if not you'll need that.

Quote:
Originally Posted by Greasetattoo
Hey Everyone,

I was wondering if anyone else was having this problem..

I was out in the field the other day flying and I got totally confused on my Mikrokopter.
I could not tell if it was flying towards me or away from me.
Almost seemed like a optical illusion?

I don't know if the copter was to far away or it was just me?

I actually came in to fast and hit the ground.
Broke a aluminum arm.
Being fixed as we speak.

I do have orange leds on the front and my front aluminum arm is painted fluorescent, with a fluorescent ping pong ball on the front.

Maybe inexperience?
This was about my 5th flight with the kopter.

I did fly the Draganflyer before this, though.
Mikrokopter is much faster!

Thanks
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Old Aug 08, 2009, 10:06 AM
13brv3's Avatar
Navarre, FL
Joined Mar 2002
3,845 Posts
Quote:
Originally Posted by Old Man Mike
This chart shows that even with balanced props, there is a sweet spot for mounting that will provide a minimum vibration level. Without testing, it is very unlikely that a low vibration will be achieved and most likely the number will be at least two times greater than the minimum. It could even be much worse. One of the five motor/prop combination had more than 6 times times the minimum vibration for some prop positions and more than 4 times as much even just 45 degrees away from the minimum position!
As usual, Mike's making me look like a slacker. I just commented on the same thing a few minutes ago on the MK forum, but of course I didn't have pictures and graphs

FWIW, I've been using Mike's method of finding the best mounting location as well, and it makes an amazing difference in most cases. The reason this works of course is because the motors aren't all that well balanced either, so you're using the imperfectly balanced prop to offset the imbalance of the motor. No matter how carefully you balance a prop, it's very rare that you end up with a perfectly balanced prop that doesn't change the vibration when you rotate it's mounting position.

You should all feel fortunate that you didn't have to endure my week of dynamic balancing experiments. Mike wasn't so lucky

Rusty
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Old Aug 08, 2009, 10:24 AM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
14,705 Posts
AJ,
I agree. But I thought you were using those pricey CF props? The APC's are more in my price hurt range, so I'm more interested...
Cheers,
Jim
Quote:
Originally Posted by MorenoEnNYC1
For an AP platform I personally feel you don't need/want precise on the dime performance such as you would for sport flying. For an AP platform you want smooth gradual response...especially for video I've used the Axi/APC combo from day one using only a lock nut (no zips or savers) without fail.
AJ
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Old Aug 08, 2009, 10:48 AM
Tinkering again!
MorenoEnNYC1's Avatar
New York, U.S.A.
Joined Aug 2007
1,367 Posts
The CF versions introduced vibrations under windy conditions so I switched back to the harder heavier plastic.

AJ

Quote:
Originally Posted by jesolins
AJ,
I agree. But I thought you were using those pricey CF props? The APC's are more in my price hurt range, so I'm more interested...
Cheers,
Jim
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Old Aug 08, 2009, 11:10 AM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
14,705 Posts
AJ,
Do you have a good source for the APC's? I've seen prices about $3 per prop at Todds models for the tractor/CCW props, but the pusher/CW props are harder to find. What sizes have worked well for you for the motors you have used?
Cheers,
Jim
Quote:
Originally Posted by MorenoEnNYC1
The CF versions introduced vibrations under windy conditions so I switched back to the harder heavier plastic.
AJ
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