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Old Feb 11, 2012, 09:34 AM
Irg
ol' yellow eyes is back
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Brooklyn, NY
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Quote:
Originally Posted by heritageflyer View Post
Ok, what if you want to run Two 6S 5000's in an 89 Slick as 12S?
easy.... Hacker Q80 8M. or go old school with the A60 18L or 16L. or wait for Ken's 50cc motrolfly. or Rimfire 50cc, though I've heard that flight times may suffer (<6 min).

plenty of options to ponder while you save up, Warren. :-)
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Old Feb 11, 2012, 09:50 AM
Fly low or fly home.
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Haha lol
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Old Feb 11, 2012, 10:08 AM
TEAM HILLBILLY
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Groveport, OH...USA
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planks theme song

Quote:
Originally Posted by plank420 View Post
Just skip through Aronphs posts, Then it's only like 5 pages
i have found it....this is planks theme song.....it are go good with pizza....crank it UP!
OFFICIAL VIDEO - "BEER!" by Psychostick (2 min 17 sec)
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Old Feb 11, 2012, 10:12 AM
TEAM HILLBILLY
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United States, MN, Minneapolis
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Quote:
Originally Posted by aronph View Post
i have found it....this is planks theme song.....it are go good with pizza....crank it UP!
http://www.youtube.com/watch?v=O-jOEAufDQ4
Beer is good
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Old Feb 11, 2012, 10:24 AM
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And stuff!!
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Old Feb 11, 2012, 10:38 AM
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Santa Clara, CA
Joined Nov 2008
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Quote:
Originally Posted by cmala View Post
that makes perfect sense. Thanks for spelling it all out for me Peter +.
I was bouncing all around what I needed but with the way you explained it now I can research some motors, esc's and batteries, populate a spreadsheet and figure out what I want.

How would I calculate flight time? I'm still finding myself drifting back and forth between gas and electric and I think the main advantage f
or gas, for me, would be run time.
Battery capacity is expressed in mAh (milliamp-hours), a 5000 mAh pack will deliver 5000 mA (5 amps) for 1 hour until it is stone cold dead, 100% discharged.

Above we calculated that on 10S we'd be pulling about 81amps to deliver 3000 watts, the reality is most of the time you won't draw that much, but let's take it as a worst-case scenario, drawing the full 81amps for the duration of the flight.

81/5 = 16, so that's 16C, 60 minutes (1C) / 16C = 3.75 minutes

That's worst case, and I was looking at 5500 packs from GensAce, so that's 81/5.5 = 14.7 60 minutes (1C) / 14.7C = 4 minutes

That's to 100% depleted, so judge it down to 80% of that, so we're talking 3-3.2 minutes, if you were going 100% the whole time.

In my experience the average draw is about 50% of the max draw, so we're looking at 6-6.4 minutes.

Same is true for the 12S 4000 packs, we're pulling fewer amps, but the pack capacity is reduced so you'd get the same times.

For a fairly significant weight penalty of about 200-300g you can go to 12S 5500 packs which will increase your theoretical runtime by about 37%, since you are adding weight I'd judge it down to about 30%. 6 minutes x 1.3 = 7.8 so you're pretty close to 8 minutes.

Of course, that's all theory and it doesn't directly account for power losses in the system as a whole. In practice I'd set a timer to a much lower number (i.e. 4 minutes), fly a "typical" flight, then check how much I put back in the pack to calculate the average C draw in practice and determine how long I can go to pull no more than 75% of the battery capacity (to allow for someone else landing before me, a go-around on landing, etc.) and set my timer there.

Peter+
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Old Feb 11, 2012, 10:40 AM
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Quote:
Originally Posted by heritageflyer View Post
Ok, what if you want to run Two 6S 5000's in an 89 Slick as 12S?
I do :-) GensAce 6S 5300 packs with a Q80-8M and a Mezjlik 24x10TH. I could easily do 8 minutes with my style (very little 3D) on that.

Peter+
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Old Feb 11, 2012, 10:42 AM
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Pvogel knows his stuff.
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Old Feb 11, 2012, 10:45 AM
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Quote:
Originally Posted by cmala View Post
Ok.

Whats the lightest way to get 3000-3500 watts and decent flight times?

How do I figure this stuff?
How do I pick kv, voltage, prop size, mAh?

All I've done in the past is compare similar plane setups

Craig
Motrolfly 5320-300 on 8S ~5000mAh spinning a 20x10 Xoar will be right about 3000W. Pretty sure this is what Losi said he was running in a 71" Slick. BTW that is a 495gr motor.
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Old Feb 11, 2012, 10:49 AM
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Quote:
Originally Posted by Eagle34 View Post
Motrolfly 5320-300 on 8S ~5000mAh spinning a 20x10 Xoar will be right about 3000W. Pretty sure this is what Losi said he was running in a 71" Slick. BTW that is a 495gr motor.
Yeah but that is only a 10 lb plane. I believe Cmala is looking to setup a 15-16lb 50cc sized plane.
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Old Feb 11, 2012, 10:58 AM
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Quote:
Originally Posted by tominator06 View Post
Yeah but that is only a 10 lb plane. I believe Cmala is looking to setup a 15-16lb 50cc sized plane.
True, but he was also asking if 3000W was roughly equal to a 30cc.
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Old Feb 11, 2012, 11:30 AM
customstandoffs
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USA, AL, Madison
Joined Dec 2007
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Yeah, 15 lb 3D plane. 3000 watts would be 200 watts/lb.

I'm thinking it should be enough.

I'm just worried that the motrofly would be too small.

They are liking the Power 160 in the EF Extra 13 lbs on 10S . Looks to be a great combo for that plane. No option for 12S though on that motor AFAIK
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Old Feb 11, 2012, 11:32 AM
Irg
ol' yellow eyes is back
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Brooklyn, NY
Joined Apr 2009
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Quote:
Originally Posted by cmala View Post
Yeah, 15 lb 3D plane. 3000 watts would be 200 watts/lb.

I'm thinking it should be enough.

I'm just worried that the motrofly would be too small.

They are liking the Power 160 in the EF Extra 13 lbs on 10S . Looks to be a great combo for that plane. No option for 12S though on that motor AFAIK
can't believe no one has asked.....but, what plane?!?!
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Old Feb 11, 2012, 11:32 AM
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Yeah the 5320 would be working hard in that size plane In my opinion. I know Ken is working on a 50cc sized motor but haven't heard how far they are from being available. Manta is pretty tight with Ken and is one of the people whoo had mentioned the 50cc motor. You might want to shoot him a Pm.
While talking to Ken about my 10s setup in my 71 he mentioned running 12s if I wanted to try it. I figured 10s was enough and am just trying to figure out the optimum prop.
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Old Feb 11, 2012, 11:37 AM
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Groveport, OH...USA
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so does anybody prefab skis for a 50cc plane?.....or am I gonna hafta make them myself?
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