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Old Aug 23, 2011, 07:39 PM
Gig 'Em!
TexasAggie's Avatar
United States, TX, College Station
Joined Nov 2010
646 Posts
30A will be plenty for the ESCs for a TS; mine are 18A.

As you're picking parts, you should be figuring out how much thrust you want and how fast you want it to go, numerically. You can use these numbers in a calculator to tell you what prop to use. I'll run a few samples for you to demonstrate:

Start with 1050kv. With an APC-E 8x8 you can get to 65 mph with 44 oz total thrust and 15.5 A per motor.
With the same motor, you could also put on a 9x6 and get 60 oz. of thrust with a top speed of 48 mph and the same 15.5 A drawn (that's probably total overkill).

With an 1100 kv motor, you could have a top speed of 51 mph, nearly 50 oz. of thrust, and 13A drawn with an 8x6.

Roughly speaking, a motor with kv between about 900 and 1300 should work fine. I use 900.

This is the calculator I'm using to come up with these values: http://flbeagle.rchomepage.com/softw..._imperial.html
A great tutorial is here: http://www.rcgroups.com/forums/showthread.php?t=1136470
If you want to play around with it yourself, the TS's numbers are:

weight: 44 oz. A pretty good estimate for an average TS
wingspan: 56 in
wing area: 676.8 sq. in.
number of props: 2
max prop size: 10

If you need any more help, shout.
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Old Aug 24, 2011, 05:30 AM
One cell short of a Pack
steve1814's Avatar
Good ole Smithsburg, MD
Joined Mar 2007
1,843 Posts
Looking for a couple of the Motor Mounts

Looking for two of the Twinstar Motor mounts. if you have one or two, PM me please!

Cheers,
Steve
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Old Aug 24, 2011, 05:17 PM
Registered User
Joined Feb 2008
100 Posts
Hi guys, bit 'off piste' but always found you guys helpful : )
Just rebuilt my TwinStar Brushless after having to buy a new wing. Would like to have said it was due to some spectacular aerial adventure but no, a drunken stumble!!!
Anyways was moving my Spektrum AR500 receiver and the tape pulled off the last silver braided bit of the Ariel away from the rest of the grey ariel.... It's about an 1" long, (2.5 cm), and does 'poke back in' but obviously won't stay there. Should I try and strip back the grey insulation and solder this peice back on or will the loss of this bit not affect the range much? Cheers, Hughie
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Old Aug 30, 2011, 09:24 AM
Pesky Landings!
bigandy's Avatar
Abergele, North Wales, UK
Joined Apr 2004
1,107 Posts
Hi Folks,

I'm considering putting together a Twinstar to use as an Aerial Photography platform. The unobstructed view from the nose will be perfect for videos. I was just wondering if anyone could tell me what the vertical distance is between the underside of the fuselage and the centreline of the motor mount? I'm looking at the sort of size props I can squeeze in there without there beinga ground clearance issue?

Thanks!
Andy
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Old Aug 30, 2011, 09:34 AM
So many UMs, so little money.
Nashville
Joined Jun 2008
380 Posts
I think 9" is the largest you can use without issue. I've noticed a lot of people, myself including, using 8x6 props with great efficiency, depending on your motor of course. I have also used 9x6, but my motors came down hot. I wouldn't feel comfortable running 10" props without landing gear.

Brandon
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Old Aug 30, 2011, 10:42 AM
**** 37130 ****
RobC(UK)'s Avatar
Joined Aug 2007
1,781 Posts
For Slide Off Ground take off, 8" are the largest diameter props you can safely use. With wheels fitted you could use up to 12" props.
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Old Aug 30, 2011, 10:45 AM
Pesky Landings!
bigandy's Avatar
Abergele, North Wales, UK
Joined Apr 2004
1,107 Posts
Cheers folks. I've not decided on motors yet, but I'll look to size them to suit a 7 or 8 inch diameter prop I want to be able to climb quickly with a decent payload onboard, so perhaps the 8 inch props are the ones to go for.

Andy
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Old Aug 30, 2011, 08:12 PM
Registered User
flyingflipper's Avatar
Joined Sep 2004
637 Posts
Brushless Power Curve

My Twinstar II is ready for it's maiden flight. When I ran up the motor on my test stand, the motors peaked at about 1/2 throttle. The battery is fully charged and the trim on the radio is trimmed right. If I pushed the stick past 1/2 throttle, there isn't any increase. I'm not looking for a speed demon - it was enough to hold it back during the run up!

The watt meter showed 360 watts and 34.5 amps.

So is what I am experiencing normal for my setup?

TP ProLite v2 3S/3300 mAh
Spektrum DX6i radio and receiver
Multiplex Power Pack:
* (2) Himax 2812-1080 Brushless Motors
* (2) 9 x 6 APC Props, (2) Hub and Driver sets
* (2) MULTIcont BL-17 ESC's

Thanks
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Old Aug 30, 2011, 08:58 PM
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antonlubo's Avatar
East SF bay
Joined Apr 2007
572 Posts
Quote:
Originally Posted by flyingflipper View Post
My Twinstar II is ready for it's maiden flight. When I ran up the motor on my test stand, the motors peaked at about 1/2 throttle. The battery is fully charged and the trim on the radio is trimmed right. If I pushed the stick past 1/2 throttle, there isn't any increase. I'm not looking for a speed demon - it was enough to hold it back during the run up!

The watt meter showed 360 watts and 34.5 amps.

So is what I am experiencing normal for my setup?

TP ProLite v2 3S/3300 mAh
Spektrum DX6i radio and receiver
Multiplex Power Pack:
* (2) Himax 2812-1080 Brushless Motors
* (2) 9 x 6 APC Props, (2) Hub and Driver sets
* (2) MULTIcont BL-17 ESC's

Thanks
According to the Himax site, those motors should output the followsing:
HC2812-1080 Kv = 1080, Rm = .111, Io = 0.75, Efficient Operating Current = 5-13A, 15A Max 15 seconds

If you're getting 34.5 amps with two motors (radio should be negligible), something is fuzzy somewhere. Did you calibrate the esc's to work with those motors? Maybe one of those more knowledgeable about such things would chime in. Good luck...Tony
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Old Aug 30, 2011, 11:17 PM
So many UMs, so little money.
Nashville
Joined Jun 2008
380 Posts
I know some ESCs require that you calibrate your throttle input. Mine did. Check the documentation of your ESCs. Mine were running completely different speeds until I calibrated them to my throttle.

Also, 34.5 amps doesn't sound good if they're only supposed to pull 26 continuous or 30 for 15 seconds. That seems to point even more at your ESCs not being calibrated to your throttle.

Brandon
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Old Aug 31, 2011, 02:09 AM
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flyingflipper's Avatar
Joined Sep 2004
637 Posts
Thanks for the advice. I'll check into this right away before I maiden it
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Old Sep 01, 2011, 05:35 PM
So many UMs, so little money.
Nashville
Joined Jun 2008
380 Posts
Has anyone mounted a GoPro to their TwinStar yet?

I'm getting one tomorrow and I'm thinking I'm probably just going to stick it on the wing as close to the fuselage as I can and angle it down and to the side. I'm wanting to do more of an aerial video/photo thing than FPV (for now ). Do you guys think that would be alright? I may have to put some counter weight on the other wing, but I'm not expecting to have to put much if any.

Brandon
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Old Sep 01, 2011, 05:45 PM
Gig 'Em!
TexasAggie's Avatar
United States, TX, College Station
Joined Nov 2010
646 Posts
Plenty of people. Youtube has lots of examples. ReadymadeRC sells a GoPro mount for the TS. Most people remove the canopy and use that space for mounting cameras. That's what I did before I lost my two... It might be a bit more complicated to get it mounted securely to the wing, but I doubt it would give the plane any problems.
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Old Sep 01, 2011, 05:56 PM
So many UMs, so little money.
Nashville
Joined Jun 2008
380 Posts
Thanks bro.

I did a search the other day and was surprised to see how many TwinStars are being used for FPV. Makes sense, though! Its where I would start if I was getting into FPV. Plenty of PayLoad.

Brandon
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Old Sep 02, 2011, 05:36 PM
Micro Flyer
United Kingdom, Marham Airfield
Joined Jun 2005
741 Posts
Hello.
just thought id drop in and say
i have a twinstar on the way! with the build focus on an FPV platform!
i thought id snoop around in here and look for a nice power set up to give me some long ish flight times!
also looking for a nice easy paint scheme. thinking Canadian search and rescue.
Chris
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