Replies to This Discussion

DeveloperPermalink Reply by jasonshort on July 15, 2012 at 9:07pm

Too heavy.

try this:

http://www.rctimer.com/index.php?gOo=goods_details.dwt&goodsid=...

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Permalink Reply by Alex Hills on July 15, 2012 at 9:19pm

I only get like 5min of flight time with two of those in parallel according to the calculator.

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Permalink Reply by Wesley Chuen on July 15, 2012 at 10:53pm

I also got the 880kV motors from the DIYDrone store but I use 10" props.  I've tried my hexa with 2x2200, 2x5000, and also 2x8400, with lift-off weight range from 3kg to 4kg with gimbal and camera.  With 2x8400 and the gimbal and camera, it is very close to the limit.  I get about 15 minutes flight time but it is not as stable in 20mph wind gust.  I would recommend using the 2x5000.

I've also tried using 12" prop, but it was really pushing the motor and the esc.

Here is a short video clip of my hexa with 2x8400 with a Contour+ camera mounted over the weekend during a local meetup.  The lift-off weight was 3.625kg.  The middle one in the video is mine.  It was very very windy when that video was shot.  You can see the hexa actually tilting to the right to fight the wind.

https://vimeo.com/45786239

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Permalink Reply by roger on January 3, 2013 at 6:41pm

Wesley,

What's the specs on the 3.625kg all lift off weight hexa you've shown in the video ...

a. by 2x8400 you mean you have a total of 16800mah ... wow that's huge!

b. propeller size was 12x47?

c. the 8400 battery what's the brand?

d. the 15minutes flying time indicated for the 2x8400, that refers to hexa you're flying in the video right?

Thanks.

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Permalink Reply by Daniel Allen on February 19, 2013 at 9:53am

Hi Wesley,

So you think having 1000g+ of batteries isn't a problem for most Hexas? Such as 2 x 5000mah 20C in parallel?

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Permalink Reply by Wesley Chuen on July 15, 2012 at 11:14pm

Just noticed that you linked a 4s battery.  Do you need to do some heavy lifting?  If not, you should either use 3s lipo or using  shorter props like 9" or 8".  Either of those gives you longer flight time.

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Permalink Reply by Alex Hills on July 16, 2012 at 3:31pm

The calculator is showing decreased flight time with shorter props.  I did find a new battery though.  How about two of these?

http://www.hobbyking.com/hobbyking/store/%5F%5F14842%5F%5FTurnigy%5...

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Permalink Reply by Wesley Chuen on July 16, 2012 at 4:32pm

You have to look at the hover time vs the flight time.  Using shorter props decrease very little hover time, but increase the flight time.  During a normal hover outdoor, it still have to increase the throttle level above the idle calculated hover percentage on each motor constantly.  So, in real life, you do want to use a shorter props with 4s, unless you need to carry heavy payloads.

But whatever, the props are cheap, get different sizes to try them out yourself and you'll see.  I did it and just letting you what my experience is.

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Permalink Reply by Johnny Yu on July 17, 2012 at 12:55am

The calculator show use 100% throttle as the bases for "flight time". Clearly a large prop will draw more current, thus lower "flight time". However, in reality, the large the prop u got, you will normally fly in lower  throttle range. 

In general a large prop gives better efficiency, but you need to account for some cons:

1. space to accommodate the increased prop size, and (may be) more structural weight

2. large angular momentum for the motor to change its speed quickly

3. vibration issues

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Permalink Reply by Vincent on July 20, 2012 at 11:14pm

Gens-ace may help you, their batteries for RC helicopter is being famous. Their headquarter http://www.grepow-lev.com is also doing a battery project of UAV, try it. 

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Permalink Reply by Alex Hills on July 22, 2012 at 5:37pm

what about a pair of these batteries in parallel?  

Turnigy Nano Lipos

also, these have a 25c discharge rate... if I use them in parallel will i get a combined 50c discharge rate?

thanks for all the replies guys :)

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Permalink Reply by Eddie Weeks on July 22, 2012 at 8:33pm

I have tried LOTs of different batteries...  They all suck...

After 3-4 months of use, every day, every other day.... They puff a bit, one cell may start to go bad.

They heat up and the end of a flight... ect... This is the same for all of them I tried so far... The latest are the 25C nano.

Zippy, Max Amps, Blue LiPo  ect...   For 5000 mah I usually put in 3000 or less...   The nano seem to last a lil longer.

Its a good thing batteries are not that much any more..

Eddie Weeks

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