Hi
I open here a thread about Scorpion kits
Note that Ralph has already spoken a lot on his works using also Scorpion kits
see for example
http://www.rcgroups.com/forums/showt...n+fan&page=402
page 402 and page 403
But this thread is very general on subjects related to Scorpion motors mainly stock-factory references + ESC

Scorpion kindly sent to me a kit S 5525 for a personal winding + test
It is a interesting kit with 18 slots and 20 magnets
Scheme for this config. is AaABbBCcCAaABbBCcC
Stator dimensions are 55 x 25 mm (diam x height) using 70 lams thickness 0.35 mm
Weight is 625 grams
As I was desiring a low Kv, I began to wind 11+11+11 turns of 1 mm wire (1.04 mm with Polyimide enamel 200°C) without Kapton tapes
but I got a short between one phase and laminations despite the Fiber epoxy end plates.
So I decided to use the factory provided Kapton tape parts in addition to the isolation end plates.
I wound only 10+10+10 turns for successive triplets like AaA ...without problems
No shorts, so I epoxied the windings to secure them and assembled the core to the stator tube placing a little screw as an axial key.
Note that I left free all the six ends A1, A2, B1, B2, C1, C2 to keep the possibility to connect Star or Delta.
I glued with epoxy the magnets inside the rotor and finished the assembly.
Then I was ready to test
Star connexion
** Rm = 0.1983 ohm
** Kv 82.3 rpm/V
** Io @ 12V =0.51A Peakeff 81.9%
** Io @ 36V =0.87A Peakeff 82.1%
Delta connexion
** Rm = 0.0661 ohm
** Kv 143.5 rpm/V
** Io @ 12V =1.08A Peakeff 84.7%
** Io @ 36V =2.12A Peakeff 87.6% located at 1190W
Iron losses
3000 rpm 32W
4000 rpm 50W
5000 rpm 72.8W
Notes
Kv Ratio Delta/star is about 1.744
As a conclusion a good motor that I plan to use inside an electric car style Shell Eco Marathon in 2010
Next discussion ASAP about a kit S5030 that I am winding now (march 2010)
Louis

Hi
I continue the thread about Scorpion kits
After my S5525 kit, I present the results regarding the recent S5030 kit

Configuration is 12 slots and 14 magnets
I have adopted a true LRK scheme A - b - C - a - B - c
Stator dimensions are 50 x 30 mm (diam x height) using 149 lams thickness 0.20 mm
Weight is less than 600 grams
I started by glueing the isolation end plates with black Epoxy 3M Scotch weld 490 and I covered also inside the slots.
As I was desiring a low Kv, I wound 50 turns of 0.71 mm wire (0.74 mm with Polyimide enamel 200°C) one tooth every two.
No shorts, so I epoxied the windings to secure them and assembled the core to the stator tube placing a little pin as an axial key.
Note that I left free all the six ends A1, A2, B1, B2, C1, C2 to keep the possibility to connect Star or Delta.
Then I was ready to test
Star connexion
** Rm = 0.787 ohm
** Kv 43.2 rpm/V
** Io @ 20V =0.14A Peakeff 85.3%
** Io @ 40V =0.165A Peakeff 88.6%
Delta connexion
** Rm = 0.263 ohm
** Kv 75.4 rpm/V
** Io @ 20V =0.27A Peakeff 88.2%
** Io @ 36V =0.32A Peakeff 90.8% located at 271W
Iron losses
1500 rpm 5.3W
2410 rpm 9.6W
3000 rpm 12.8W
Notes
Kv Ratio Delta/star is about 1.745
As a conclusion a good motor that I plan to use inside a solar-electric car style Shell Eco Marathon in 2010
For this application I commutate star-delta by a 3 poles on-off relay
I use Scorpion Commander 50V 90A ESC under 36 V
Louis

Hi
My friend Olivier bought a Scorpion kit S4035 -10 poles to be used as a very low Kv motor for his big helicopter Bell 206 (tail rotor drive):
** Main rotor diameter : 3.4 m
** weight : 30 kg
The desired Kv was around 105-110 rpm/V to be run under high voltage (same voltage as the main rotor).
He asked me to calculate and to make the windings.
After averaging the products Kv x turns of the 3 factory S4035 (10P)-330-380-460, I adopted that new configuration :
True LRK 6 coils Wye (A-b-C-a-B-c-) , 25.5 turns per tooth + 10 magnets
(25.5 turns means that the first tooth A phase starts from the stator side and that the tranfer to opposite tooth at 180 deg is made rotor end bell side)
I used 0.71 mm copper wire from http://www.wires.co.uk (polyester 200°C, non solderable)
Stator dimensions are 40 x 35.8 mm (diam x height) using 172 lams thickness 0.2 mm
First the stator(12 slots) was coated by Epoxy Electrolube TBS (light blue)
Kapton tape was provided by Scorpion but not used
The 3phase windings were good at first attempt (no shorts !!)
So they were also coated by epoxy to prevent any bad freedom
I left outside the stator flange the 3 phases + the neutral (4 ends)
The rotor was provided with the magnets installed at Scorpion factory.
Ball bearings are two NMB 1680 (metric 8x16mm)
One is going stator flange, the second is mounted directly in the laminations (end bell side)
No problem to slide the rotor shaft.
Final weight is 430 grams.

Then I was ready to test. The motor ran very smooth at the first drive on my bench.

Star connexion
** Rm = 0.420 ohm @ 20°C (preliminary measurement)
** Kv measured = 112 rpm/V (low timing)
** Io @ 24.1V =0.24A rpmo = 2690 Peakeff 87.1%
** Io @ 42.1V =0.31A rpmo = 4725 Peakeff 88.9%
No load (iron) losses are only 12W around 4500 rpm

Efficiency under 44.4V (12S) is > 75% up to 19 A (850W) corresponding to an APC 22x12 prop providing a 4.3 kgf static thrust and a 68.5 km/h pitch speed.

Louis

Great report, Louis! An inspiration to us all!

I noticed you say you used a non-solderable wire and don't understand the use of that.

Looking at the wire specifications I can see the wire you used has a better heat rating (200C over 155C for solderable wire) but does it also mean that you cannot solder the connectors on?

Jack

Originally Posted by jackerbes

Great report, Louis! An inspiration to us all!

I noticed you say you used a non-solderable wire and don't understand the use of that.

Looking at the wire specifications I can see the wire you used has a better heat rating (200C over 155C for solderable wire) but does it also mean that you cannot solder the connectors on?

Jack

Hi Jack
No
You have just to scratch off the enamel (mechanical action)
I use a simple cutter all around the wire on 20 mm length end
For single strand 0.71 mm it is not so difficult
But for multi-strands thin wires it could be tedious
Unfortunately, I have no motorized "enamel eraser" head or tool
Louis

OK, so the wire will take solder OK but not until the coating is removed.

I have been using the Micro Dan wires and have to do the same thing. I use an EXacto knife blade held perpendicular to the wire and scrape all around, then I lay it flat and hit it with some 100 grit or so emery cloth to shine it up and get everything off. It is more work but worth it to have that tough coating on the wire.

I tried using a small sanding drum in a Dremel tool but it was too aggressive, it would eat the copper right up if I put any pressure at all on it.

Have you ever tried the trick with laying the wire on a aspirin tablet and using a soldering iron? I tried that and it did not work for me.

Jack

Hi Jack
Same for me, aspirin is not working on that enamel.
But it works when I have some pain myself
Louis

Hi
We got a Scorpion kit S4535-10 poles (or HK4535) to be used as a medium Kv motor for a solar car prototype style Shell Eco Marathon (Paris West University IUT Ville d'Avray team)
The desired Kv was around 170 rpm/V .
I adopted the following configuration, after some calculated estimation :
True dLRK 12 coils (AabBCc aABbcC) , 10 magnets
Half parallel opposite 22.5 turns per tooth (22.5+22.5) (transit end bell side), DD
I used 0.51 mm copper wire from http://www.wires.co.uk (polyester 200°C, non solderable)
with the enamel coating, diameter is 0.57 mm
The windings were realized (april 2012) by a newbie professor assistant (Bernard) under my supervision and with my help. The room in the slots was easy for the 22.5 turns. Probably good for 24 turns and lower Kv..
I was the CCW-CW guide and the turns counter. It was my pleasure to teach some know how. Bernard's hands and fingers are pretty good (stronger than mine).

Stator dimensions are 45 x 37.2 mm (diam x height) using 175 lams thickness 0.2 mm
Stator is equipped with glass fiber epoxy end plates
First the stator(12 slots) was coated by Epoxy Electrolube TBS (light blue)
Kapton tape was provided by Scorpion but not used
Slot area is about 33.7mm2
All 3phase windings were good at first attempt (no shorts !!)
So they were also rapidly coated by epoxy to prevent any bad future freedom
I left outside the stator flange the 6 phases ends
The rotor was provided with the curved magnets installed at Scorpion factory.
Airgap around 0.4mm
Outer diameter is 56.7mm
Shaft is 10mm reduced to 6mm on the stator flange side
Ball bearings are two metric 10x19x5mm, labeled Singapore
Final total weight is 592 grams. Stator 204.5g + 294.5 g copper. Rotor 293.5g

Then I was ready to test. The motor ran very smooth at the first drive on my bench.
Results for Delta connexion, Half parallel :
Note that I soldered 4mm bullet gold connectors with 3 slightly different lengths of wires
** Rm = 0.13 ohm @ 20°C
** Kv measured = 171 rpm/V (low timing)
** Io @ 24V =0.51A rpmo = 4110 Peakeff 89.5%
** Io @ 16V =0.42A rpmo = 2730 Peakeff 88.4%
No load (iron) losses are only 11.4W around 4000 rpm

Finally we glued a 8mm stainless tube to get an output shaft fitting our 8mm pinions hole.
The kit is really superb.
Louis

very impressive motor.