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Jul 23, 2020, 08:43 PM
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Wingerbill's Avatar
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Anyone recognize this motor?

You all are so good at identifying some unknown aircraft I have picked up, here is a chance to do the same with a motor. Obviously an outrunner, it is 43mm in diameter and 47 mm long. It has absolutely no identifying marks on it anywhere, looks like 12 poles (little difficult to count accurately through the holes).

I am particularly interested in the propeller adapter. I suspect there must be an inner spacer/washer that fits over the hexagonal part of the shaft, but I do not have it. The motor was acquired in a box of miscellaneous stuff at an R/C swap meet, and all I have is what's in the picture. I have not been able to find any adapter that looks similar to this one. I do not know if there is a motor shaft sticking out on the front that the adapter fits over, or if it just bolts onto the motor, one of the screws is frozen and I have not been able to successfully remove it yet. If I can find the proper spacer for it I won't bother, because I am liable to have to destroy the adapter to get the screw out, and don't want to chance that until I know that I have an alternative.

Bill Perry
Caldwell, Texas
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Jul 23, 2020, 08:59 PM
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It looks like a V1 Torque Motor, but it looks more like a copy of one.
Jul 23, 2020, 09:06 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
A safe starting point, conservative rule of thumb for motorpower: 3 to 4watt max. powerhandling per gram motormass.

Four simple straightforward methods for determining the velocity konstant Kv, rpm for given voltage:
→ Motor constants
→ The speed constant or velocity konstant (Kv)

Note that the velocity konstant Kv is not a rating, not a figure of merit, not a design/production achievement.
More about what the velocity konstant Kv stands for

Vriendelijke groeten, en wees voorzichtig, Ron
• Without a watt-meter you are in the dark ... until something starts to glow •
e-flight calculatorswatt-metersdiy motor tips&tricksCumulus MFC
Jul 23, 2020, 10:14 PM
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Wintr's Avatar
That looks the same as the motor for my Airfield Sky Trainer, but the diameter is a bit more. That hex part fit into the back plate of a spinner in my case; I'd assume the same for yours.
Jul 24, 2020, 12:49 PM
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Wingerbill's Avatar
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Ok, I managed to get the prop adapter off without damaging the adapter, so here are some additional pictures. The motor has no output shaft, so the prop adapter bolts on, the hole is about 11mm. The prop adapter does have a hole in the shaft for a screw to hold a spinner on, so I suspect that the piece I am missing is the spinner back plate, which must be fairly thick because there is 20mm of unthreaded shaft between the flat on the adapter and the threads to hold the prop on. I guess I will be trying to find the missing piece for this adapter, or trying to find an alternate adapter with the same size center hole and screw pattern.

I did look up a V-1 Torque Motor, it does look similar but without the shaft. I found a chart listing all the Torque Motor specs, the biggest motor on that chart was 180 grams, 2812T/720, 55 amps. This motor weighs in at 220 grams, but using the formula Ron provided as a starting point, that would calculate out to about 720 watts, which looks like the same size as the biggest Torque Motor.

Jul 24, 2020, 02:42 PM
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The 4016 Toque Motor weighed more then 200 grams, 480kv I think.
Jul 26, 2020, 10:22 PM
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Wingerbill's Avatar
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Finally found the information I needed. This motor is an FMS 4250 KV500 that is used in an FMS P-51 Mustang with a 1400mm wingspan. There is a spinner that is specific to the Mustang that fits over the hex on the prop adapter. The spinner is a 4 bladed spinner for the Mustang. My thanks to AMain Hobbies for finally confirming this info and hooking me up with the spinner. There is also a company called Small Parts Cnc that makes a prop adapter without the hex that fits this motor, it has a longer shaft so you can use a variety of propeller configurations. There are numerous conversations on RCGroups that address this particular adapter.

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