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Old Aug 05, 2011, 11:32 PM
Flying low is expensive.
pdiddyg40's Avatar
United States, CO, Boulder
Joined Jul 2008
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There's no airflow, and the prop isn't able to 'unload' it's power as it would be in the air. It puts more stress on the motor and will generally cause it to draw a couple more amps. I feel that it's fine to bench test motors, but not run them for long periods of time. If yours is running long enough to get hot, it's too long IMO. I normally run them long enough to get accurate readings on my watt meter and then shut it off.
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Old Aug 05, 2011, 11:39 PM
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rcplanes1234's Avatar
United States, IA, West Des Moines
Joined Jan 2010
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Quote:
Originally Posted by pdiddyg40 View Post
There's no airflow, and the prop isn't able to 'unload' it's power as it would be in the air. It puts more stress on the motor and will generally cause it to draw a couple more amps. I feel that it's fine to bench test motors, but not run them for long periods of time. If yours is running long enough to get hot, it's too long IMO. I normally run them long enough to get accurate readings on my watt meter and then shut it off.
The motor only ran for a minute or so on the bench and got hot just in that period of time.
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Old Aug 05, 2011, 11:54 PM
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United States, CA, Sebastopol
Joined Dec 2010
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Quote:
Originally Posted by rcplanes1234 View Post
The motor only ran for a minute or so on the bench and got hot just in that period of time.
A minute can be a long time. Motors heat up fast if they're drawing too many amps.
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Old Aug 06, 2011, 04:56 AM
UAV Pilot
UndCon's Avatar
sweden
Joined May 2007
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Quote:
Originally Posted by pdiddyg40 View Post
There's no airflow, and the prop isn't able to 'unload' it's power as it would be in the air. It puts more stress on the motor and will generally cause it to draw a couple more amps. I feel that it's fine to bench test motors, but not run them for long periods of time. If yours is running long enough to get hot, it's too long IMO. I normally run them long enough to get accurate readings on my watt meter and then shut it off.

I don't think that is true...

Static on ground full throttle test



In flight full throttle at a few moments


Now explain why the measured loads are greater in air...I do believe in my own logs.

Flying upwards at WOT most likely require more power than static on ground.

I can verify this by opening the logfile and see the load at a specific moment - ie when climbing vertically
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Last edited by UndCon; Aug 06, 2011 at 05:01 AM.
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Old Aug 06, 2011, 05:07 AM
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Joined May 2009
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Could it be greater in air because prop gets lots of air? Static test in ground is different because prop have to suck air?

Props
One guy explained to me that pusher prop is designed differently compared to normal props.
Pusher props have more thrust on end of props than normal props? Is that true? Why is that, because airflow is affected by frame and props don't get clean airflow?
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Old Aug 06, 2011, 05:18 AM
Smoke on , go !
zaguruinzasky's Avatar
Verona - Italy
Joined Jan 2007
2,527 Posts
Hey there's a SW V4 at my door looking for new friends !! Auuuuuuuuuuuuuu !!!
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Old Aug 06, 2011, 05:52 AM
Smoke on , go !
zaguruinzasky's Avatar
Verona - Italy
Joined Jan 2007
2,527 Posts
I'm probably make mine twin engine with custom motor pods on the leading edge of the wings.., less lipo to balance it, more efficient position of motors.. what do you guys think ? a Twin Sky Walker Star....
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Old Aug 06, 2011, 06:55 AM
Houba ! Houba !!
rcmonster99's Avatar
United Kingdom, England, Milton Keynes
Joined Sep 2003
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Quote:
Originally Posted by zaguruinzasky View Post
I'm probably make mine twin engine with custom motor pods on the leading edge of the wings.., less lipo to balance it, more efficient position of motors.. what do you guys think ? a Twin Sky Walker Star....
double engine, double trouble...plus wiring complications and lengthy setup on the ground before take off.
I think there is not a lot to improve on the SW. In my book, if it ain't broken, don't fix it.... and that would be in contravention with my KISS rule

that's my personal opinion...
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Old Aug 06, 2011, 06:59 AM
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Joined Nov 2008
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Quote:
Originally Posted by UndCon View Post

Now explain why the measured loads are greater in air...I do believe in my own logs.

Flying upwards at WOT most likely require more power than static on ground.

I can verify this by opening the logfile and see the load at a specific moment - ie when climbing vertically
if the prop is stalled with static test it will draw less?
if the SW has not reached top speed, it is more like a static test?
try wot straight and level.
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Old Aug 06, 2011, 10:47 AM
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United States, IA, West Des Moines
Joined Jan 2010
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Can a use a 8x6 prop with that motor.
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Last edited by rcplanes1234; Aug 06, 2011 at 11:17 AM.
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Old Aug 06, 2011, 03:27 PM
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United States, IA, West Des Moines
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Im going to go to the hobbyshop and pick up a 8x6 and see what happens.
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Old Aug 06, 2011, 04:23 PM
Never fly an A model anything!
jayb1rdz's Avatar
Antarctica
Joined Apr 2008
4,983 Posts
I put my SW in yesterday for it's first major. I run mine with tri- gear and a change of wind direction forced a different approach to usual. My base turn was too near and I ran out of runway so I opened up the throttle to go round and BOOOoooof. Into a 4m high earth mound. It looked lower every other time I flew over it!!

Front gear is mashed. Tail boom ripped at the fuse, pilot is feeling stupid. All fixed overnight except I have realized that the P&T and cam mount are still buried on the mound somewhere.

It seems it will be a while before I am flying with Mooses and carving through the gaps on the trees. J
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Old Aug 06, 2011, 08:27 PM
I do all my own crashes
Wingnut13's Avatar
United States, NH, Rochester
Joined Jan 2011
243 Posts
^^Sorry to hear of your crash, good luck getting it back in the air!

Today was the first time I put my SW V2 up with the RVOSD Gen4 in charge. I've spent the last few days setting up the autopilot. One scary moment when I flipped the RTH switch for the first time and it took a wicked dive.... I took control over and pulled up...hard! Tested the wing strength as well, GTG.

I'm happy, I would have played with the A/P more but in my rush forgot my second battery on the charger. Also looks like it will rain for the next week, glad to get it up!

~Wingnut13
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Old Aug 07, 2011, 06:57 AM
Houba ! Houba !!
rcmonster99's Avatar
United Kingdom, England, Milton Keynes
Joined Sep 2003
6,195 Posts
Quote:
Originally Posted by Wingnut13 View Post
^^Sorry to hear of your crash, good luck getting it back in the air!

Today was the first time I put my SW V2 up with the RVOSD Gen4 in charge. I've spent the last few days setting up the autopilot. One scary moment when I flipped the RTH switch for the first time and it took a wicked dive.... I took control over and pulled up...hard! Tested the wing strength as well, GTG.

I'm happy, I would have played with the A/P more but in my rush forgot my second battery on the charger. Also looks like it will rain for the next week, glad to get it up!

~Wingnut13
My second SW is also equipped with the same OSD.... So far I am only using it as a OSD. One day I must summon the courage to enable the RTH...
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Old Aug 07, 2011, 09:27 AM
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Avenger GBU-1H's Avatar
Acworth, GA
Joined Mar 2007
225 Posts
Quote:
Originally Posted by zaguruinzasky View Post
I'm probably make mine twin engine with custom motor pods on the leading edge of the wings.., less lipo to balance it, more efficient position of motors.. what do you guys think ? a Twin Sky Walker Star....
I remember you had mentioned doing this once before about 2000 replies ago. That would be an awesome build design if you can get the physics just right.

What kind of motors would you use? How would you mount them? I would really like to see the finished product.


Good luck! Keep us updated!
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