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Old Nov 14, 2014, 01:17 AM
Livin it UP when Im goin DOWN
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Keith: have you pinned the front cap of your ARC? If so, you can easily run a 16x17S on 5S.
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Old Nov 14, 2014, 01:49 AM
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Quote:
Originally Posted by mustflynow2 View Post
http://www.rcgroups.com/forums/showt...158876&page=16

Have you seen here, from post 231, what do you think?
Just read it now ---I dont think at those amps and watts it will be reliable on 7s. longer term.

I will probably test 6s with a similiar prop to keep revs just under 60k.

Will get a backfire eventually ---have a spareNeu 1115 2.5d with 6.7 will prop with 17.5 x 17.5 on 7s @ 2000 watts plus that should push it along nicely.

Regards Keith
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Old Nov 14, 2014, 02:08 AM
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Quote:
Originally Posted by keithmoor View Post
Just read it now ---I dont think at those amps and watts it will be reliable on 7s. longer term.

I will probably test 6s with a similiar prop to keep revs just under 60k.

Will get a backfire eventually ---have a spareNeu 1115 2.5d with 6.7 will prop with 17.5 x 17.5 on 7s @ 2000 watts plus that should push it along nicely.

Regards Keith
Just did some number crushing on that set up on E Calc :-

On 6s with a 14.5 x14 prop it pulls 131 amps 2340watts 9381 thrust 9035 revs 120mph .

Thrust is up to 9381 ------------------but efficency has dropped to 24.6%
and its only 3 mph faster than my proposed set up @ 84 amps 1493 watts 86.1% efficency.

Exactly as I expected

Regards Keith
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Old Nov 14, 2014, 02:33 AM
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Quote:
Originally Posted by Arcteryxxx View Post
Keith: have you pinned the front cap of your ARC? If so, you can easily run a 16x17S on 5S.
.
No --but it's a good idea,thanks --I have some fiber glass tape wrapped around it

I have a rfm 16 x 16 s I could try on 5 s but :-

16 x 16 = 157amps 2534 watts 10331 Thrust 7654 revs 116mph

Again thrust is up to 10331g but top speed is down and efficiency is very low

How much thrust is really needed this is a small glider AUW will be in vicinity of 1500g .and its not for competition flying.

If it was a 3000g 3m hotliner then yes prop it 17 +

Regards Keith
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Old Nov 14, 2014, 01:59 PM
Livin it UP when Im goin DOWN
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Needed? Never been the question around here. Limits and possibilities are more normal things to wonder about, my friend
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Old Nov 14, 2014, 04:50 PM
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Quote:
14 x9 and 5 degree offset ,
Did you calculate that Prop as a "regular"14x13 and compared it to the other mentioned Props in E-calc?

Yello
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Old Nov 15, 2014, 12:44 AM
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Quote:
Originally Posted by Mreyello View Post
Did you calculate that Prop as a "regular"14x13 and compared it to the other mentioned Props in E-calc?

Yello
No ---I just put in 14 x 9 plus the 5 offset , a regular 14 x 13 would probably be better.

I've been using various props which I have on hand plus 2.5 and 5 degree offsets to get a rough idea of a reasonable efficient set up.

At this stage it looks like it will be 14 x 13 or 14 x 14 on 5s --maybe I should look at 14.5 Rfm.

Using 4s at the moment with 14 x 9 plus 5 ---even that is just effortless.

Thanks and Regards Keith
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Old Yesterday, 11:47 PM
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Cool testing the Hawk F5B

Still waiting on my 5s--any day now ---in the meantime here's a copy of the castle log on 4s --77.8amps 1122watts 34.2C 7593rpm

This was the initial launch--subsequent motor runs were about 2 secs duration back to height

Any comments guys ---Regards Keith
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Last edited by keithmoor; Yesterday at 11:52 PM.
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