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Reviving an old TwinStar

Running on LiPo's

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Stephen Belshaw17/02/2019 16:21:18
106 forum posts
24 photos

I have one of the original TwinStar's, originally flown on a 7 cell Nicad, and having brought it out of a long hibernation I'm now wanting to fly it on LiPo's. I have put in a 2S which is obviously lower voltage than the original battey, and it shows.

Although the model is around 200g lighter, even with added noseweight, it struggles to get airborne and after one very hairy circuit I'm relieved to get it down in one piece. I'm wondering if I could fly it on 3S, the Pico Duo Control 400 ESC caters for a max of 14.4V, it still has the original motors which are "Permax 400" rated at 6V I think.

Can I just slot a 3S battery in, will the ESC and/or motors take it, would I need to change the props? Or would it be better to swap out the motors?

Edited By Stephen Belshaw on 17/02/2019 16:22:17

Former Member17/02/2019 16:32:32

[This posting has been removed]

Frank Skilbeck17/02/2019 16:49:17
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4674 forum posts
101 photos

Stephen, I did exactly as you suggest, just chucked in a 3s lipo and away I went, but first off the push on props kept flying off, so I fitted prop adaptors and some other small propellers, the performance was great for a few flights until one of the 400 motors burnt out.

Rather than replace the burnt out brushed motor I hacked my Twinstar and fitted a couple of brushless motors.

Stephen Belshaw17/02/2019 16:59:22
106 forum posts
24 photos

Frank, that's pretty much what I thought - that the motors would end up totalled in short order.

I've got 3S batteries, the duo control ESC would presumably still do the job so just fitting new motors would be my preferred option. What would you suggest for motors?

Percy, I've looked for the replacement powersets but cannot find anything for less than the cost of a new kit - am I missing something??

Stephen Belshaw17/02/2019 17:10:02
106 forum posts
24 photos

And still running on 35Mghz ..............

twinstar (1).jpg

Trevor Crook17/02/2019 17:37:14
938 forum posts
67 photos

Stephen, your brushed motor esc would need replacing too (with a brushless one for each motor), and remember you'll need to run 3 wires to each brushless motor. The Twinstar was a good flier in its original form, should be a great one with a brushless setup.

Former Member17/02/2019 17:42:32

[This posting has been removed]

Frank Skilbeck17/02/2019 17:45:30
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4674 forum posts
101 photos

Stephen I used 2 small E-Max motors, can't find then but these are a couple cheap alternatives, fitted with 7 x 4.5 props, 3,000 mah 3s lipo and 20 amp ESCs. I use a separate RX battery so disconnect the redwire from the ESCs. I also plug them into separate channels on my Rx and have rudder-throttle mixing as I have made mine a tail dragger and this is essential for on ground steering.

Former Member17/02/2019 17:57:27

[This posting has been removed]

Stephen Belshaw17/02/2019 18:12:50
106 forum posts
24 photos
Posted by Percy Verance on 17/02/2019 17:57:27:

There you go Stephen. Frank's solution looks as good as anything. yes

Indeed it does Percy - thanks Frank!

Paul Marsh17/02/2019 18:35:40
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3956 forum posts
1182 photos

i have the original one, with standard 400's. I put a 3s Lipo, and so far after a few flights, the motors are still going - they were rattling and worn, but both are still ok.

Only problem, is that the 2200 3s i much lighter than the 7 cell Nicad and have to put 2 in the nose just to get it to balance, and still too light, so put two 3s 3000mah and ok, i just plugged one in, and swapped to the other when after 15 mins, I remember just having a 5 min flight with the 1800's 7.4v Nicad which was hopeless.

I also flown my cargo, using a 4000mah 3s, and again, have to use two as it's still too light...

Frank Skilbeck17/02/2019 19:45:09
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4674 forum posts
101 photos

here's a photo of my brushless installation

twinstar motor.jpg

Stephen Belshaw17/02/2019 21:44:50
106 forum posts
24 photos

Thanks Frank, that's very helpful - pop a ply former in and mount the individual ESC's immediately behind, then form a "Y" lead for connection to the battery I presume?

As I've nothing to lose I think I'll do what Paul did and hammer the motors with a 3S until they give up, then switch to the brushless set-up.

Frank Skilbeck17/02/2019 22:10:18
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4674 forum posts
101 photos

I mounted my ESCs on the underside of the wing just by the fuselage, I scalloped out some the foam so they sit flush with the wing surface, held in with some tape.

Re using the brushed motors on a 3s, if the plane starts flying weird when you throttle up, cut back and land, you've burnt one of the motors out surprise, this is what instigated my change to brushless wink

Mike Stevens18/02/2019 07:46:04
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464 forum posts
57 photos

I converted mine to brushless and much better performance - can recommend it.

Stephen Belshaw18/02/2019 07:47:04
106 forum posts
24 photos

Thanks for all the suggestions, so my proposed set-up would be:

ESC **LINK**

Motors as suggested by Frank: **LINK**

A couple of 7 x 5 props, CW or CCW or one of each and run in opposite directions?

Wiring of system as here: **LINK**

Run from a 3S LiPo.

Mike Stevens18/02/2019 07:49:23
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464 forum posts
57 photos
Posted by Stephen Belshaw on 17/02/2019 21:44:50:

Thanks Frank, that's very helpful - pop a ply former in and mount the individual ESC's immediately behind, then form a "Y" lead for connection to the battery I presume?

As I've nothing to lose I think I'll do what Paul did and hammer the motors with a 3S until they give up, then switch to the brushless set-up.

Unless you burn one motor out in flight and then have to fly asymmetric to get back to terra firma laugh

Frank Skilbeck18/02/2019 08:32:40
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4674 forum posts
101 photos
Posted by Stephen Belshaw on 18/02/2019 07:47:04:

Thanks for all the suggestions, so my proposed set-up would be:

ESC **LINK**

Motors as suggested by Frank: **LINK**

A couple of 7 x 5 props, CW or CCW or one of each and run in opposite directions?

Wiring of system as here: **LINK**

Run from a 3S LiPo.

Yep, should be fine, I think my ESCs are 20A , I went with Option 3 on the wiring diagram but put the throttles on separate channels, mainly because I had added undercarriage and also because I could.

Stephen Belshaw27/09/2019 12:34:44
106 forum posts
24 photos

It's been a while but I've finally got round to doing this!

All the components are now in the airframe and I just need to conect the ESC's, I'm intending to use this option.

I have run the motors independently to check prop direction but I'm not sure how I program the ESC's (brake) - do I set them up seperately before I wire them together (Y-lead in to one throttle channel) or can they be programmed together as a single unit?

Paul Marsh27/09/2019 15:36:17
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3956 forum posts
1182 photos

I've flown my mk1 Twin Star on the original motors,but they survived on a 3s Lipo, but have to use a 4000mah battery as the 2200 3s are much lighter than the 7.2v 1800 mah Ncad I used to use. Also have a Twin jet, but those were 6v 380 motors and fried both using 3s Lipo, but found a set of 7.2V 400 motors, which looks like seems to accept the higher voltage and hasn't burnt out.

Also have a Cargo, same motors, and they are still working.

Edited By Paul Marsh on 27/09/2019 15:38:05

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