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Old Oct 03, 2012, 09:15 PM
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Doug Bartley's Avatar
Canada, ON, Owen Sound
Joined Oct 2008
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Hi JMorgan: I've been following along every once in awhile, very interesting project.
I would guess without searching your using Scorpion 4025-12 (440kv) motors. I would strongly suggest using 4025-16 (320kv) on 6S for this application with your 16/8/4 bladers. They should pull around 65a in real life. When you go generic in Scorp Calc, its so far off as to be laughable.
I just completed testing with 6S on a 16/12/ 3 blade Graupner propeller for a build, 56a,1300watts actual. FWIW Doug Bartley
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Old Oct 03, 2012, 09:21 PM
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bdelapen's Avatar
United States, FL, Pembroke Pines
Joined Aug 2008
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Just a refresher, here are the motors J is running:

http://www.rcgroups.com/forums/showp...&postcount=477

He is running 80A ESCs.

- B
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Old Oct 03, 2012, 10:33 PM
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ZRX212's Avatar
United States, FL, Christmas
Joined May 2010
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Hi, I have been silently followed several of your builds, all excellent!!!.
I would try testing with both motors connected to batteries and watt
meter hooked up to a single motor to see if your numbers drop, also
check this link http://www.hobbyking.com/hobbyking/s...ner_Motor.html

it list 5-8s lipos, maybe you can use a 5 cell ??, maybe I'm wrong, just
trying to help.

Hope you figure it out, Allen(ZRX212)
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Old Oct 03, 2012, 10:44 PM
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J Morgan's Avatar
Chapel Hill, TN USA
Joined Apr 2001
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Quote:
Originally Posted by bdelapen View Post
Just a refresher, here are the motors J is running:

http://www.rcgroups.com/forums/showp...&postcount=477

He is running 80A ESCs.

- B
Yeah, but that's a little misleading since my wattmeter was maxed out at 70A and I didn't even know it.

All great info guys. These motors are supposedly designed to run on a minimum of 6s. Same thing with the escs, 6s minimum. Therein lies my problem. I can't reduce cells to reduce the amps. Plus the four blade props have a safety rating to 8,000 rpm.
About the only way is to prop down on two blades and see what I can find that balances thrust with amps.
I did read on the HK site that one individual ran this motor on 6s-5000 and a 16x10 prop. That gave about 80A at full throttle. Probably could live with that.
It's way too late to order motors of course but maybe I have something in the shop that might work in case I can't find a happy medium.
And my problem is twofold, with the A-1 Skyraider. It has the same setup and I will have to change it out too. I have my work cut out for me tomorrow and Friday it looks like.

J
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Old Oct 03, 2012, 10:57 PM
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United States, FL, Pembroke Pines
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Quote:
Originally Posted by J Morgan View Post
Yeah, but that's a little misleading since my wattmeter was maxed out at 70A and I didn't even know it.

All great info guys. These motors are supposedly designed to run on a minimum of 6s. Same thing with the escs, 6s minimum. Therein lies my problem. I can't reduce cells to reduce the amps. Plus the four blade props have a safety rating to 8,000 rpm.
About the only way is to prop down on two blades and see what I can find that balances thrust with amps.
I did read on the HK site that one individual ran this motor on 6s-5000 and a 16x10 prop. That gave about 80A at full throttle. Probably could live with that.
It's way too late to order motors of course but maybe I have something in the shop that might work in case I can't find a happy medium.
And my problem is twofold, with the A-1 Skyraider. It has the same setup and I will have to change it out too. I have my work cut out for me tomorrow and Friday it looks like.

J
I know it's not 100% accurate but eCalc should get you in the ballpark. APC 16X10 E seems like they will work, 82A peak with fully charged packs. Here is the eCalc printout.

Regards,

- Birger
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Old Oct 03, 2012, 11:15 PM
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Chapel Hill, TN USA
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Thanks Birger,
I have 16x10s coming tomorrow to try. Hope they work out. Appreciate the help!

J
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Old Oct 04, 2012, 06:53 AM
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austria
Joined Aug 2004
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Hi John,
here are measurement datas of a Turnigy motor with 3-and 4 blades:
ww.rc-wasserflieger.at/forum/thread.php?threadid=209&sid=&page=1

Regards
Herbert
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Old Oct 04, 2012, 06:56 AM
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austria
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..now it works.
http://www.rc-wasserflieger.at/forum...09&sid=&page=2
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Old Oct 04, 2012, 09:18 AM
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Chapel Hill, TN USA
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Thanks Herbert.
More numbers to consider. Hated to see that beautiful seaplane go in but looked like it wasn't damaged too badly.

J
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Old Oct 04, 2012, 01:08 PM
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J Morgan's Avatar
Chapel Hill, TN USA
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Got the new props in. I ordered APC 15.5x12 ( Nut said he had used them before) but after my wattmeter debacle I knew they wouldn't work. And 16x10s too.
So I put one of each on and ran one motor at a time on 6s-5000 batts.
So it's official, I am using the 15.5x12 props and entering the AC-119K in the speed contest with all those damned EDFS!!!!
The 15.5x12 on a single motor gave 90A and 2100 watts!!!!! Wow, motors wouldn't last long.
The 16x10 was much more promising at 55A and 1250 watts. So I put the other 16x10 on and ran a thrust test. Got 19 lbs thrust, lends me to believe they may be usable. At least they shouldn't destroy the motors.
We haven't given up yet on the big four bladers, have one more thing to try before I do. Time is running out, Hans will be here in 48 hours. We leave Monday and Sunday will be all packing and maybe just a little flying.

J
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Old Oct 04, 2012, 01:11 PM
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United States, FL, Pembroke Pines
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Quote:
Originally Posted by J Morgan View Post
Got the new props in. I ordered APC 15.5x12 ( Nut said he had used them before) but after my wattmeter debacle I knew they wouldn't work. And 16x10s too.
So I put one of each on and ran one motor at a time on 6s-5000 batts.
So it's official, I am using the 15.5x12 props and entering the AC-119K in the speed contest with all those damned EDFS!!!!
The 15.5x12 on a single motor gave 90A and 2100 watts!!!!! Wow, motors wouldn't last long.
The 16x10 was much more promising at 55A and 1250 watts. So I put the other 16x10 on and ran a thrust test. Got 19 lbs thrust, lends me to believe they may be usable. At least they shouldn't destroy the motors.
We haven't given up yet on the big four bladers, have one more thing to try before I do. Time is running out, Hans will be here in 48 hours. We leave Monday and Sunday will be all packing and maybe just a little flying.

J
Hi J,

Just to make sense of the numbers, those 15.5X12 are four bladed and the 16X10 are 2 bladed, correct?

- Birger
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Old Oct 04, 2012, 02:15 PM
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Sorry Birger, I should have restated that.
Yes, the 15.5x12 are four bladerd and the 16x10 are two bladed.
Getting ready to run my final test and I'll post those results a little later.

J
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Old Oct 04, 2012, 05:42 PM
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Chapel Hill, TN USA
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Here are the results of the final motor test. These motors are set up for 6s-12s lipos. But we wanted to see how they would operate on 4s in order to see if the big four bladed props might be used. I set up one side with a Suppo 70A esc and used a fully charged 4s-5000 and the 16x8 four blades. Results were 46A and 740 watts. So clearly that won't get it done.
It looks like the plane will have to fly on the 16x10 two blade props on 6s-5000 batts. That gives almost 90watts/lb and at least 19 lbs thrust. That should get the job done..... hopefully

J
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Old Oct 04, 2012, 07:22 PM
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United States, IN, Granger
Joined Jan 2003
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Don't have any 5S around ??? that might take you there .
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Old Oct 04, 2012, 08:40 PM
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Nelson, B.C.
Joined Jun 2008
150 Posts
Cherokee flyer & Wilfor
FYI, an AC clip on ammeter on the load side of the esc will give you bang on current readings.
Kim
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