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Twinstar 2 counter rotating props?

Old 11-14-2009, 04:44 AM
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Catalina
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Default Twinstar 2 counter rotating props?

Hi, have just ordered a twinstar 2 off ebay and am going to upgrade it with brushless outrunners and 3 bladed 8 x 4 props. I know that the multiplex motor mounts on these planes are angled at the mount end to the right hand side. Are these mounts at an angle to compensate for a certain motor direction or can I make one prop go CW (clockwise) and one go ACW (anti-clockwise) like I had previsoly done with my now dead catalina.
Also are the plastic mounts strong enough to hold the outrunners or should I modify.
Any help would be great.
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Old 11-14-2009, 05:12 AM
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you'll want'um dead ahead no right thrust, Counters cool and take-off runs are dead strait but I fly my twin's both ways and do fine, GWS props.com is a good place for counter three blades you want and spinners too, Mounts are cheap so get some as well, your gonna need two ESC's on you brushless set up, and don't forget to cut one of the ESC's power wires (middle red one) to the RX or better yet use a UBEC, Your new set-up will really put your twin-Star on after-burner, bubsteve
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Old 11-14-2009, 06:02 AM
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I have a multiplex minimag with the same angled motor mount and it flies great (and straight) so I thought there must have been a reasoning as to why they were designed with a slight angle. I know of other forums where guys have used everything stock on a twinstar 2 and had no problems with those mounts, however I dont know if they were running one in reverse which could cause an issue. I have all the electronics out of my catalina (2 X 30A ESC, motors , props etc) but I did not cut that red wire you were talking about above and all worked OK.
What I really want to know is will that angled mount (that comes in the twinstar 2 kit) work OK if I use a counter rotate prop/motor on one side?
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Old 11-14-2009, 07:20 AM
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No, it won't work very well. It's possible you could get away with it, but the right-angled mount is intended to compensate for an aerodynamic effect of clockwise-rotating propellers. With a counterclockwise propeller, you need the mount angled to the left. With a twin, rather than angling the motors both ways like this, you can also get by just fine with both motors pointed straight forward.

Also note that you typically want to have the right-hand motor spinning counterclockwise and the left-hand motor spinning clockwise (that is to say, with the blades moving downward close to the fuselage and upward towards the wingtips). This gives you the best single-engine/engine-out behavior, in the event of an emergency.
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Old 11-14-2009, 02:30 PM
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I have the same plane mounted emax motors using the supplied mounts. Flys great and have no problems to date. I have about 30 ish flights on the plane and not a problem. With the motor mounts supplied they have tabs built into them, on the narcel of the wing there is a slot that the tabs slide into. This sets the motor's up with no thinking on the builders part. For got to add I don't have counter rotating props on my setup.

Last edited by gramps2361; 11-14-2009 at 02:57 PM.
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Old 11-14-2009, 05:02 PM
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Sparky Paul
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Electric twins are much less prone to single-engine flight than fuel motors.
It's neat to have the counter-rotation setup, but not really needed.
If one motor fails, pull the power back a lot and determine which one failed, then fly accordingly, with the caveat that full power on the running motor may be more than the aerodynamic controls can handle.
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Old 11-15-2009, 01:13 AM
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[QUOTE=Catalina;661272]I have a multiplex minimag with the same angled motor mount and it flies great (and straight) so I thought there must have been a reasoning as to why they were designed with a slight angle. I know of other forums where guys have used everything stock on a twinstar 2 and had no problems with those mounts, however I dont know if they were running one in reverse which could cause an issue. I have all the electronics out of my catalina (2 X 30A ESC, motors , props etc) but I did not cut that red wire you were talking about above and all worked OK.
What I really want to know is will that angled mount (that comes in the twinstar 2 kit) work OK if I use a counter rotate prop/motor on one side?[/QUO
Most folks and myself have alot of probs not cut'in it, Yours isn't cross'in up yet and it's always recommended that you do cut one when not use'in a UBEC and cut'in both, I got away with it for a while then it bit me an I went-in hard! Hope it works for you but my four twins go on one power source ,, bubsteve
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Old 11-15-2009, 08:28 AM
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Originally Posted by Sparky Paul View Post
Electric twins are much less prone to single-engine flight than fuel motors.
It's neat to have the counter-rotation setup, but not really needed.
If one motor fails, pull the power back a lot and determine which one failed, then fly accordingly, with the caveat that full power on the running motor may be more than the aerodynamic controls can handle.
Thanks for all your replys. Sparky, the only real reason I was going for 1 counter rotating prop was because I heard with 2 motors/props spinning the same way you can get some torque tuning issues (plane wants to vear to one side). But I assume that with the Twinstars angled mounts they have compensated for this.
So in conclusion to what you guys have advised I will go for the 2 motors/props to spin clockwise (I think!) and cut one red wire off my Y-harness that leads to one of my ESC's. I am assuming this will make the other ESC provide all power to the servo's etc.
On the flip side, wouldnt it be better to have 2 supplies to servos in case an ESC died mid flight?
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Old 11-15-2009, 03:21 PM
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Originally Posted by Catalina View Post
On the flip side, wouldnt it be better to have 2 supplies to servos in case an ESC died mid flight?
That's a very unlikely failure. Unless you leave them both connected, and they're fighting each other to provide power to the servos at slightly different levels, in which case one could pretty easily overheat. Basically, having them both hooked up would be a neat safety feature which will probably only be necessary because you have them both hooked up.
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Old 11-15-2009, 03:36 PM
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Originally Posted by Catalina View Post
Thanks for all your replys. Sparky, the only real reason I was going for 1 counter rotating prop was because I heard with 2 motors/props spinning the same way you can get some torque tuning issues (plane wants to vear to one side). But I assume that with the Twinstars angled mounts they have compensated for this.
So in conclusion to what you guys have advised I will go for the 2 motors/props to spin clockwise (I think!) and cut one red wire off my Y-harness that leads to one of my ESC's. I am assuming this will make the other ESC provide all power to the servo's etc.
On the flip side, wouldnt it be better to have 2 supplies to servos in case an ESC died mid flight?
.
It's not torque with twins, it's P-factor.
Torque operates around the fore-and-aft line of the motor-prop.
Fuselage mounted motored planes will "torque roll".
With wing mounted motors, it's the asymmetric thrust that does the yaw-roll manuver.
It would be interesting to make a twin 3D plane, with individually controlled motors to demonstrate this.
And don't cut the red wire in the ESC harness. Cut the red wire in an extension harness instead and use that between the ESC and the receiver. Fixing the original harness can be a problem, so just avoid having to do that at all.
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Old 11-15-2009, 04:23 PM
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Originally Posted by aramid View Post
That's a very unlikely failure. Unless you leave them both connected, and they're fighting each other to provide power to the servos at slightly different levels, in which case one could pretty easily overheat. Basically, having them both hooked up would be a neat safety feature which will probably only be necessary because you have them both hooked up.
You'll plow your plane if you leave it like that,
Don't take my word for it,,check it out,,
I've built 8 or so twins and may have learned something in the last near 50 years of do'in this, good luck, bubsteve
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Old 11-15-2009, 08:04 PM
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Originally Posted by Sparky Paul View Post
And don't cut the red wire in the ESC harness. Cut the red wire in an extension harness instead and use that between the ESC and the receiver. Fixing the original harness can be a problem, so just avoid having to do that at all.
Either do this or just remove the red wire from the plug (it's pretty easy to do, you just need to lift up a little plastic finger), fold it back along the wire, and heatshrink it out of the way. You don't want the red wire connected, but there's no sense in permanently damaging the wiring.
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Old 11-16-2009, 11:17 AM
  #13  
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Originally Posted by aramid View Post
Either do this or just remove the red wire from the plug (it's pretty easy to do, you just need to lift up a little plastic finger), fold it back along the wire, and heatshrink it out of the way. You don't want the red wire connected, but there's no sense in permanently damaging the wiring.
Thanks guys. Ok, you have all convinced me, I will definately remove (not cut) a single red wire to one of my ESC's and I will leave both motors spinning in a CW direction with the original mounts.
Just have to get the plane now. Purchased 3 days ago but want it now. Ahhhh, this hobby is addictive.
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Old 02-02-2010, 08:11 PM
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Originally Posted by gramps2161 View Post
I have the same plane mounted emax motors using the supplied mounts. Flys great and have no problems to date. I have about 30 ish flights on the plane and not a problem. With the motor mounts supplied they have tabs built into them, on the narcel of the wing there is a slot that the tabs slide into. This sets the motor's up with no thinking on the builders part. For got to add I don't have counter rotating props on my setup.
gramps, can you please tell me what direction your props are spinning. CW or CCW when looking at prop front on with motor behind.
Thanks
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Old 02-02-2010, 08:43 PM
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They both spin ccw looking at it from the front. Still working on yours?

John
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Old 02-03-2010, 07:45 PM
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Originally Posted by gramps2161 View Post
They both spin ccw looking at it from the front. Still working on yours?

John
Yeah I have just finished, been busy with kids going to school for the first time and all that stuff.
OK mine both spin the other way, do you think it will cause an issue or should I get the soldering iron once again?
I must of put on my counter rotating props on by mistake and wired my motors to produce thrust in the right direction.
So CCW is the correct direction with these angled mounts I take it?
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Old 02-04-2010, 03:03 AM
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If you used brushles motors just switch any wire from the motor to the esc and that will change the rotation of the motor.
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Old 02-04-2010, 03:07 AM
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I understand the whole kid's thing yours sound a lot younger and they do need more time from you, and give it to them cause before you know it they will be grown up and you and the wife will be like what happened.
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Old 02-05-2010, 08:16 PM
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Well, flew it for the first time yesterday. All went well. Hand lanched without a problem. This plane does fly very well even with very little throttle. Only issue I noticed is that it always wanted to roll to the right. I could trim this out but was wondering why. Is it because of both motors spinning in that direction with the large 8 x 4 3 bladed props on. Do you have this problem also gramps?
Anyway with the watt meter at WOT was measuring approx 38 amps. My 3cell 30C battery was quite hot when I landed (ran at 3/4 throttle most of flight). Might have to get a bigger C rating battery.
Landing was very easy as this plane just floats.
All in all a very nice plane. Did do some tricks (loops, invertered etc) but it is a nice plane just to fly scale.
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Old 02-05-2010, 10:20 PM
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What motor are you using to be using a 3 blade prop? Post the motor size and spec's for the motor, and the battery size it shouldn't be coming down hot.
The roll to the rt. sounds like a trim issue with the ailerons. Mine I am using 2 emax motors 2812 and 7x4 APC prop . No I don't have a issue with a torque roll caused by the motors.
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Old 02-06-2010, 12:20 AM
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I am using these motors:

http://www.hobbycity.com/hobbycity/s...idProduct=2046

And these props:

http://www.hobbycity.com/hobbycity/s...idProduct=5247

Battery is a 3 cell 30 C 2450mAh.
2 X 30A ESC's

This combo should be fine I think as long as I dont use max throttle continuely.
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Old 02-06-2010, 01:11 AM
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Ya know I don't have a clue why the battery would be hot. Seems people are running 15c batteries with no issues with a single motor and 3 blade prop. Try using 8x4 apc prop see if that makes a difference with the battery temp. You don't want to smoke the battery. These motors are amp hungry. At 38 amps I beleave if I did it right you are produceing 444.6 watts at WOT the motor is rated to 200 watts max so you are pushing the motor and the battery I'm sure. With that much power this must move right along. Wonder what your getting for thrust on this setup.

Maybe some one will chime in with more knowledge in this area than I have.
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Old 02-06-2010, 01:22 AM
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You might want to make sure there's a set of vents to provide a bit of airflow through the fuselage - that might help keep your batteries cool.

Still, if you decide to upgrade your battery, you'd be better off getting a bigger battery, rather than one with a higher C rating. The Twinstar will easily carry even a massive 5000 mAh pack, which will double your flight time as well as handling the amps better.

Since amp capability is C rating times capacity, increasing either one helps with setups drawing a lot of amps. There's absolutely no reason to spring for more expensive 30c and 40c packs unless power-to-weight ratio is critical for your application, and flight time is irrelevant (a 30c discharge gives you 2-minute flights; 40c gives 90 seconds). Most modelers would be just fine with 20c or even 15c packs - typically only helicopter pilots and crazy people will actually use more than 20c.
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Old 02-08-2010, 01:01 PM
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OK, crashed the twinstar badly today, bent the nose, snapped the 2 white plastic wing retainers, bent both motor shafts, snapped props and ripped a 3 inch cut in the wing.
Got the nose back to being almost straight. Am changing out the outrunners to the following:

http://www.hobbycity.com/hobbycity/s...idProduct=5203

with 6x4 props. This is the same combo as in my minimag and it works great there.
Will take me a while to get the parts in howerver.
Dam this hobby.
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