One hour CD ROM motor construction PART2 - Page 14 - RC Groups
Jan 07, 2004, 09:48 PM
Why not Delta?
Quote:
 Originally posted by rcflyer2 ...and test was done with a 2s1p E-Tech 1200s ... WOT test with a zagi prop 5 1/4 x ? Thrust= 7.3oz WOT amps=9 WOT volts=8.4 WOT 2nd Test with 6030 prop Thrust=10.1oz WOT amps= 5.5 WOT volts= 6.7 WOT This is the prop for this motor!

1. You can't get 8.4V from 2x 1200 LiPo at 9 A - something is not right here.
2. To get 10 oz thrust from 6x3 you need to spin it about 12700 rpm and put the output power around 45W. In your second test you got motor with 120% efficiency (you give 5.5A * 6.7V = 37W).

Here my calculations based on your data:
1-st test (as I remember Zagi prop is 5.25 x 5.25)
RPM = 14100 rpm
Power out = 62.5 W
Power in = 75.6 W
Efficiency = 83 %
rpm/V = 1683 rpm/V

2-nd test:
RPM = 12700 rpm
Power out = 44 W
Power in = 36.9 W
Efficiency = 119 %
rpm/V = 1900 rpm/V

RysiuM
 Jan 07, 2004, 10:28 PM Registered User I am using a Astro flight Watt meterr and only posting what it says? I never let it stay at that amp draw more then a couple sec, and I will run it again just to be sure? At the lower amp draw 5.5 it will run WOT and not heat up? And I think the firs test was on a 3s1p 1200 I;ll check. Scott
 Jan 07, 2004, 10:38 PM Registered User O.K. I re-tested with both the 2s1p and the 3s1p E-tech 1200s results: 2s1p A=5.4 V=6.5 W=36 3s1p A=7.2 V=8.4 W=63 Both tests are with the 6030 prop. Now I'll do it with the zagi prop and post results!
 Jan 07, 2004, 10:45 PM Registered User O.K. 2nd test with the zagi prop 2s1p A=7.0 V=6.2 W=44 3s1p A=9.2 V=8.0 W=74 There ya go! Scott
 Jan 09, 2004, 06:41 AM Registered User I like the progress and information you guys are sharing... As I am interested in doing one of these cd-rom convertions for my micro heli (hummingbird), I have some questions as to: What type of winding (delta or star)? Magnet wire guage? How many turns? Any suggestions?
Jan 09, 2004, 11:43 AM
Registered User
I think I've posted a photo of this one before, most likely in the original "homemade brushless" thread. However, today is the first time I've had all of the equipment together to get good readings. I pulled this motor from an unknown CD-ROM drive, and just mounted it to a fiberglass plate, soldered on my connector, and added a prop adapter and prop. As shown, with an MPJ 3mm prop adapter, Dean's 3-pin connector and APC 7x5E, it weighs 1.375oz / 39g. I have flown the motor in a small bipe, but it probably needs rewound to get the best from it. With a 7-cell 1000SCR (just for testing, of course), it spun the 7x5E at around 5000rpm (hard to get a good reading with the lights off in the shop and using a flashlight). Current draw was 1.7A. After several minutes of running, the motor was barely warm to the touch.

Tony Turley

PS: Anybody else snowed in? We only got about 3" total, but it has a layer of ice glaze beneath it. I tried to stop going down a steep hill less than 1/4 mile from my home to help a guy who was in the ditch, and ended up in the same ditch myself!! Fortunately, he has an uncle who lives nearby and works for the local power company. He used the winch on his truck to rescue us both. I decided that was pushing my luck enough, and came back home and called in.

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 Jan 09, 2004, 11:58 AM Registered User Tony- Do you know how much static thrust you're getting with that setup? I'm impressed that you successfully flew a plane on the stock windings. Not much snow on the ground here, although we had a 18" snowfall in mid-December. The big story here is the temperature = below zero F at noon. - Jeff
 Jan 09, 2004, 12:08 PM Registered User Jeff, No, I don't have any way of measuring thrust. Tony Turley
 Jan 09, 2004, 12:09 PM Registered User Well, it was enough to fly an airplane, which is what matters! - Jeff
Jan 09, 2004, 01:04 PM
Well, my magnets came in yesturday. For the mount I used an old EPD 50XC motor can that I totally gutted (took out the magnet and bushing).

Here's the first tests

Weight: .8 oz. (22.6 grams)

Prop: 4.75x4.75 APC
Battery: 3s1p 1200 ETEC
Amps: 8.4
R.P.M: 16,200
Watts: 78W
Static Pitch Speed: 73 m.p.h.

Prop: 4.5x4.1 APC
Battery: 3s1p 1200 ETEC
Amps: 7.2
R.P.M: 18,000
Watts: forgot (I'll post later)
Static Pitch Speed: 62 m.p.h.

I'll test other props later. I think the 6x3 will work very well, although it would have a pretty slow pitch speed of around 40 m.p.h.

This motor is more powerful than the 010. It swings the 4.75x4.75 prop 1,200 r.p.m. faster than the 010, pulling 1.5A more than the 010. I know it is slightly less efficient than the 010, BUT WHO CARES It only cost around \$3.00! It is also .8 oz. where the 010 is 1.3 oz.

-- Acer
http://speedwing.net

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Last edited by Acer; Jan 09, 2004 at 01:23 PM.
Jan 09, 2004, 01:07 PM
I'm going to put this in my original Mini SpeedWing. If I use 3s1p 340 Kokams I'll have a wing the same weight as my 4 oz. MSW and MUCH faster . It'll fit right into the stock mount.

Here's a picture of the winds (Note: I didn't heat shrink the leads yet, didn't have heat shrink small enough).

-- Acer

### Images

Last edited by Acer; Jan 09, 2004 at 01:19 PM.
 Jan 09, 2004, 07:19 PM Registered User Very nice, Acer. This afternoon I was testing the rewind I mentioned a few posts back. It is the one with a smaller, thicker stator. I rewound it with 10T of dual-strand #26. I used the stock magnet ring at first, but I'm going to replace the magnets with N45s. I can't seem to get good tach readings, though. My tach indicates 3600 with the lights on, so I have to turn off all of the lights and try to get the readings by flashlight. I even put a small piece of white electrician's tape on the back of the prop, but the readings jump around too much. If the tach is to be believed, the motor spins a Gunther 5x5 black prop at around 11K at 6A from 7 cells, at about 2/3 throttle. It won't go much higher, though. When the current reading hits about 8A, the rpms suddenly drop, and the motor gets erratic. Below 3/4 power, however, it runs very smoothly. The worst part is that the prop thrust overcame magnetic forces, and the bell went flying across the room, taking one of my precious 3x6 mm bearings with it. I never found the bearing. Tony Turley
 Jan 09, 2004, 07:43 PM Lipoly not Lipo-suction Hi guys. I may have missed this question in an earlier post but............. How do you fix the stator to the aluminium post? Thanks. Cranky.
Jan 10, 2004, 02:14 PM
Hi Wattage Electrics - Cool

# First CD rom motor flight

I flew my first CD rom motor today, this is a photo before the maiden flight. It powers a slow stick really well, performing much like the stock motor. This CD motor uses a 3.75 gear reduction (GWS A) and the stock grey CD rom magnet. My next step is to replace the current magnet with some 5x5x1 N45's. Hopefully I'll get a little more thrust.