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Old Nov 28, 2011, 06:19 PM
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Awsome discussion guys, I'm really liking the info in this thread and it's being conducted in a very calm rational manor. Great job. A lot of food for thought.
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Old Nov 28, 2011, 06:28 PM
Facts, Logic, 3D
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If all this info is food... I need a nap!

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Old Nov 28, 2011, 08:10 PM
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AP,
The link below shows some static test result of the Torque 2814/820 kv with different propellers at multiple throttle positions. I think different prop pitch would affect the slope of the thrust vs. watt curve.
http://www.rcgroups.com/forums/showt...+static+thrust

Vien
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Old Nov 28, 2011, 08:10 PM
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Originally Posted by Aeroplayin View Post
What will provide the definite evidence, one way or the other, is if the lower pitch straightens out the Amp and Thrust graph plots. As they are now, they go up sharply, then flatten out at the top. If the 16x6 shows relatively the same leveling off, then we're better off riding the 16x8 to 83 percent than the 16x6 to 83 percent. If the curve stays at virtually the same angle all the way to the top, then the 16x6 would be the better prop option. If it was not raining out today, I'd have put the 16x6 on it and reported back by now, but we'll all have to wait.
Yes! That is what I'm talkin' about! Can't wait
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Old Nov 28, 2011, 09:25 PM
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Quote:
Originally Posted by Aeroplayin View Post
What will provide the definite evidence, one way or the other, is if the lower pitch straightens out the Amp and Thrust graph plots. As they are now, they go up sharply, then flatten out at the top. If the 16x6 shows relatively the same leveling off, then we're better off riding the 16x8 to 83 percent than the 16x6 to 83 percent. If the curve stays at virtually the same angle all the way to the top, then the 16x6 would be the better prop option. If it was not raining out today, I'd have put the 16x6 on it and reported back by now, but we'll all have to wait.
Holy cow look what has been up!

Now this thread is getting crazy interesting! Perhaps finding the optimum prop not based on WOT but rather a dialed back percentage throttle setting? Ringing out the absolute maximum system performance and prop efficiency to boot. Now your thinking!

Love it. Stellar spin off concept. Iíll take a second helping please.
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Old Nov 28, 2011, 09:30 PM
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While we're waiting... here's the mashed potatoes

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Old Nov 28, 2011, 09:40 PM
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Originally Posted by leespaddock View Post
Perhaps finding the optimum prop not based on WOT but rather a dialed back percentage throttle setting?
I love data but it doesn't always tell the whole story.

I used to do IT management consulting and I collected a lot of hard data. However, that was not the complete story. There is a human element that factors into the equation. It's the soft data I got by looking around and talking to people thaat gave me the complete view of what was going on.

Similarly, I am looking forward to the subjective data from the guys who fly the props and give us their opinions - the soft data.

I think this matters because nobody does 3D at WOT for the entire flight, in fact WOT is a small percentage. Nope, not even at 5/6 throttle. I suspect the average is around 40-50%.

This sure is a very interesting discussion!

Bring on the pilots picks!

JC
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Old Nov 28, 2011, 10:07 PM
Not as Good as The Kid
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Quote:
Originally Posted by vienquach View Post
AP,
The link below shows some static test result of the Torque 2814/820 kv with different propellers at multiple throttle positions. I think different prop pitch would affect the slope of the thrust vs. watt curve.
http://www.rcgroups.com/forums/showt...+static+thrust

Vien
Vien -- I just browsed this brefly and was wondering if you thought they actually picked a measured throttle setting, or moved the throttle until they reached a desired RPM setting? It looks like the are stepping the RPMs and then reading thrust, relating the two kinetic variables, but I'm not sure. I'll check it out more tomorrow when I have time. I have two projects going with dealines of January 6th.

I see where it says, "Experiments have been done in a stepwise fashion where RPM is increased."

Here is a taste of some of the 16x8 data, but because we were not able to collect most of the multiple plot points on the same day, same motor, same battery, etc, we will probably have to retest again the next time out.

http://www.rcwebclub.com//Portals/rc...06S%20Amps.pdf
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Old Nov 28, 2011, 10:22 PM
Not as Good as The Kid
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I may as well display the thrust along with the Amp data. This was Frank's data taken independently to include the additional plot points, as Vien suggested.

http://www.rcwebclub.com//Portals/rc...S%20Thrust.pdf

The Xoar is more linear and the APC seems to flatten out quite a bit in the last 1/6th of the throttle setting.

I use the term, 'flatten out', but it could be either pitch distortion or stalling considering the relative Amp reading. Either could explain the less thrust and less Amps at full.
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Old Nov 29, 2011, 08:33 AM
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So this is the first case in which the APC outperforms the Xoar in the thrust department, yes? Given the nature of 3D flight the APC should give better performance all around.
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Old Nov 29, 2011, 10:57 AM
Not as Good as The Kid
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So this is the first case in which the APC outperforms the Xoar in the thrust department, yes? Given the nature of 3D flight the APC should give better performance all around.
That's what it looks like. When I first got the data from Frank, I was scratching my head because the 15x8 data from Lee did not show this at 1/2 throttle, although the readings were very close. Franks was also not able to take RPM readings because of the low light conditions, so my intent is to rerun all readings for the 16x8 along with the 16x6 Vox test, but I will have to do it on the Motrolfly because we don't have the 500Kv Torque.

Regarding the top end performance... I think the visual video of the pullout from hover will determine, for each individual pilot, how worthwhile the top end performance really is. My feeling is that this will be a very subjective decision, and if guys see a big difference, they may not care as much about the minor difference in the lower setting data. This is where the flight visuals can really override the graph data display conclusions.
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Old Nov 29, 2011, 11:00 AM
Not as Good as The Kid
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I may have to get a 12x6 too so we can test both on the Torque 820Kv. This will give us 12x6, 14x7, 15x8, and 16x8 comparisons and see if any of the lower setting results are consistent.
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Old Nov 29, 2011, 12:20 PM
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If you could put the amp draw at hover, guessing half throttle, and then the amp draw at punchoit I think that would be a nice to have as overlays. This is going on youtube so it shouldn't be to hard, I am guessing here.


Also about the timing issues on the force that you asked about in the edge thread. I dint have a 150g motor yet but will probably be able to test it out on a sk3 800kv this weekend. I would guess the torques will come back in at the end of the month.
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Old Nov 29, 2011, 09:47 PM
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Originally Posted by stgdz View Post
If you could put the amp draw at hover, guessing half throttle, and then the amp draw at punchoit I think that would be a nice to have as overlays. This is going on youtube so it shouldn't be to hard, I am guessing here.


Also about the timing issues on the force that you asked about in the edge thread. I dint have a 150g motor yet but will probably be able to test it out on a sk3 800kv this weekend. I would guess the torques will come back in at the end of the month.
They may already be in, so check EF if that's the motor you decided on.

I wish I had some onboard logging, and I think this is another reason to go with the CC Ice 100A on the Motrolfly.
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Old Nov 30, 2011, 06:31 AM
2.3 D Hack Bradenton FL
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Originally Posted by Aeroplayin View Post
They may already be in, so check EF if that's the motor you decided on.

I wish I had some onboard logging, and I think this is another reason to go with the CC Ice 100A on the Motrolfly.
Jim, I have an Eagle Tree logger with the sensors that I used to dial in the Yak. Anybody know if a current sensor is available?
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