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Dec 31, 2012, 05:04 PM
An Aussie in Chicago
Quote:
Originally Posted by TexasAggie View Post
  • Weight: around 73 oz.
  • Motor: 920 kv Emax BL2820/07 from HURC (http://www.headsuprc.com/servlet/the...ushless/Detail)
  • Prop size: 9x6, 10x5, 10x6, 10x7
  • ESC: Hobbywing 40A
  • Separate BEC: Castle 10A
  • Servos used: HS-82MG x4 on wings (noisy little buggers); HS-65HB x2 on tail
  • Flight battery: 1 Sky Lipo 4S 4000 mAh
  • Video battery: small 3S
  • Flight cam: RMRC 480
  • VTX: 400 mW Sunsky
  • VTX antena: DIY Cloverleaf
  • RX: Sunsky or Lawmate
  • RX antenna: DIY Virevent or Skew-planar wheel
  • Stabilizer: GWS PG-02 dual-gain, switchable via Tx
  • OSD: Remzibi OSD
  • Max wind: about 25 knots
  • Mods: flaps, motor mount, carbon ribbons in wings/stabilizers, proper hinges and control hardware.

Some prop data for my motor. Admittedly, it's not very helpful since I don't have a tachometer and therefore, have no way of measuring thrust.

10x5:
Max current: 29.59 A @ 15.88 V
Max power: 469.9 W
Min voltage: 15.64 V

10x6:
Max current: 34.98 A @ 15.77 V
Max power: 551.5 W
Min voltage: 15.45 V

10x7:
WILL UPDATE

You can measure static thrust using one of the light weight kitchen scales. The one I have has a max of 11 lb capacity and cost $10 from Amazon.

With a rear engine plane like the Skywalker. Just place the nose on the scales and hold it vertically up side down. The apply full thrust and check the scale, then just subtract the planes weight giving you thrust. Best with 2 people.

You don't need the wings attached or anything like that.
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Dec 31, 2012, 05:29 PM
Gig 'Em!
TexasAggie's Avatar
Sounds like a nightmare as far as safety goes. I think I'll just buy a tachometer...
Dec 31, 2012, 05:31 PM
Registered User
Daemon's Avatar
Tachometer isn't going to tell you much about thrust.
Dec 31, 2012, 05:34 PM
Gig 'Em!
TexasAggie's Avatar
With the Flybrushless data it will. For instance, http://flybrushless.com/prop/view/78
Dec 31, 2012, 05:36 PM
An Aussie in Chicago
Quote:
Originally Posted by TexasAggie View Post
Sounds like a nightmare as far as safety goes. I think I'll just buy a tachometer...
Its not hard or unsafe at all with 2 people. Anyway its the only way to get real static thrust figures.

You can also do this without the plane...just the motor and ESC & battery and some device to hold the engine @ full throttle.
Dec 31, 2012, 05:44 PM
Gig 'Em!
TexasAggie's Avatar
I'd rather not take that risk. If the prop shatters it could end up in my chest or something. The less time the prop's plane of rotation spends intersecting me the better. For me, it's not worth that much to get a few numbers.

I updated my main post with more data.
Last edited by TexasAggie; Dec 31, 2012 at 05:55 PM.
Apr 03, 2013, 01:27 AM
Registered User
Hi guys
I need max flight time for a 1.8kg skywalker

should I use:
http://www.hobbyking.com/hobbyking/s...00kv_550w.html
OR
http://www.hobbyking.com/hobbyking/s...dProduct=18231

OR none of those ?

AND what prop ?
Apr 03, 2013, 11:09 AM
Mini Obsessed
Shadrack's Avatar
What type of flight time? You looking for an hour? I can get close to that with an OS 3820-1200kv and on a 3S 5100 I can glide along for 45 minutes with throttle management. Have had my amp use down to just over 3 amps in level flight. I run a 9 x 6 as a prop and never go much past half throttle except for launch.
Apr 03, 2013, 07:00 PM
If it's to be, it's up to me.
subsonic's Avatar
Quote:
Originally Posted by jasonyyd View Post
Hi guys
I need max flight time for a 1.8kg skywalker

should I use:
http://www.hobbyking.com/hobbyking/s...00kv_550w.html
OR
http://www.hobbyking.com/hobbyking/s...dProduct=18231

OR none of those ?

AND what prop ?
That's what this thread is for, isn't it? Have you read any of it?

You didn't mention what battery you are going to use. 3S? 4S? 12S?

The original Skywalker is pretty much limited to a 9" prop, unless you're keen on moving the motor up and accepting the slight handling compromise that goes with it.
Apr 03, 2013, 11:53 PM
Registered User
FWIW, theres not much reason to install the motor on the plane to test it...

there is going to be little effect on its efficiency on the plane vs a simple wooden mount attached to whatever scale you have. It would certainly reduce measurement error and risk. When I see thrust measured in grams and the idea of balancing a 2kg plane in the mix... little sirens go off in my head.

For that matter, this thread could be as well applied to any plane... The design of planes may impede the airflow to the motor, but I should think this should be both negligible, and consistent between motor/props on the same plane. The most efficient motor and prop to push 1kg of thrust should be the most efficient for EVERYONE (desiring that amount of thrust anyway). but then, the individual units across production runs may not be so consistent for different people.
Apr 04, 2013, 12:32 AM
Registered User
Quote:
Originally Posted by subsonic View Post
That's what this thread is for, isn't it? Have you read any of it?

You didn't mention what battery you are going to use. 3S? 4S? 12S?

The original Skywalker is pretty much limited to a 9" prop, unless you're keen on moving the motor up and accepting the slight handling compromise that goes with it.
FYI:
I'm looking for the best "combination" for this much weight on the plane.
Doesn't matter if I end up using 3s, 4s....
Doesn't matter which prop, I knew the max is 9xX but isn't there still plenty of people are using bigger ones(thus I know I know it need to be modified...).

Again, there is only 1 thing can't be changed, is the weight of 1.8Kg....
That's why the weight is the only information I provided.
Apr 04, 2013, 04:28 AM
Registered User
Daemon's Avatar
Doesn't change the fact that the information you want is already in the thread.
Many people list their weight, and cruise amps. Look for the one that
best matches what you want. It's best to convert cruise amps to watts
Watts = volts (3S versus 4S nominal voltage) * amps, so you can
compare apples to apples. If want individual response, all you'll get
is people telling you that their own setup is best.

Besides, this thread is not for questions, it's for listing proven setups.
Apr 04, 2013, 04:37 AM
9W2DLR
Quote:
Originally Posted by jasonyyd View Post
FYI:
I'm looking for the best "combination" for this much weight on the plane.
Doesn't matter if I end up using 3s, 4s....
Doesn't matter which prop, I knew the max is 9xX but isn't there still plenty of people are using bigger ones(thus I know I know it need to be modified...).

Again, there is only 1 thing can't be changed, is the weight of 1.8Kg....
That's why the weight is the only information I provided.
have search this thread? if you did you should find this post by subsonic what more do you need?

https://www.rcgroups.com/forums/show...v#post21484280

as ian said this thread is not for questions, it's for listing proven setups. people need to learn how to use search button
Apr 06, 2013, 03:36 AM
Registered Loser
First the forum coders need to make a search that works well.
Apr 06, 2013, 03:42 AM
Registered Loser
btw.. what does "proven" mean? I think a lot of the setups shown here are VASTLY over powered. I'm using this motor with mine with a dinky 18A ESC... something I got laughed at when I first suggested it. But it works, and I get far more flight time than someone using a 600W monster motor. Granted, I can't even dream of doing a flip or climbing at a steep rate... but that isn't (in my opinion) what this plane is all about.


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