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OS Motor OMA-5025-375 .

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Old 07-17-2013, 12:44 AM
  #1
drac1
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Default OS Motor OMA-5025-375 .

Hi guys,

I am considering purchasing the OS OMA-5025-375.

Can anyone provide some info in regards to the performance and prop size etc. of this motor.?

Information appreciated.

Scott
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Old 07-17-2013, 04:25 AM
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Default RE: OS Motor OMA-5025-375 .

Hi,

In what plane do You plan to use the motor in?

/Bo
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Old 07-17-2013, 04:49 AM
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Default RE: OS Motor OMA-5025-375 .

Hi Bo,

The Beast 60e from e flite. I know it is a 60 size, but the motor e flite recommends won't be available for a while. Looking at OS specs it seems like it may be ok.
I haven't had much experience with electrics and i would be interested in others opinions. It may not be adequate for hard 3D flying, but if replies indicate it would be suitable for normal flying I may give it a go until the e flite motor is available.

Scott
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Old 07-17-2013, 06:03 AM
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bem
 
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Default RE: OS Motor OMA-5025-375 .



OK,

Beast 60e ARF specification:
http://www.e-fliterc.com/Products/De...ProdID=EFL9000


Here is the specification on E-flite "Power 60" Brushless Outrunner:
http://www.e-fliterc.com/Products/De...odID=EFLM4060B
Power 60 Brushless Outrunner Motor, 470Kv
Key Features
Perfect for 6- to 12-pound (2.7- to 5.4-kilogram) airplanes
High torque, direct drive alternative to brushless inrunner motors
Includes mount, prop adapter and mounting hardware
Quiet, efficient operation
External radial rotor design
Designed for high power applications, this 6S motor is ideal for 60-sized planes, or models that require up to 1800 watts of power.



Product Specifications
Type: Brushless outrunner
Size: Replacement for 60-size glow engines
Bearings or Bushings: One 6 x 15 x 5mm bearing and two 6 x 12 x 4mm bearings
Wire Gauge: 14 AWG
Recommended Prop Range: 15 x 8 - 17 x 7 electric propeller
Voltage: 22.2V (6S LiPo, 4400-5000mAh)
RPM/Volt (Kv): 470Kv
Resistance (Ri): 0.02 ohm
Idle Current (Io): 2.1A @ 20V
Continuous Current: 65A
Maximum Burst Current: 80A for 15 seconds
Speed Control: 80A brushless
Weight: 13.0 oz (380 g)
Overall Diameter: 2.00 in (50mm)
Shaft Diameter: 0.24 in (6.0mm)
Overall Length: 2.40 in (62mm)


Specification OS OMA-5025-375:
http://www.osengines.com/motors/moto...ane-index.html
(.50 Size)
Rotor Diameter (mm): 50
Magnet Length (mm): 25
kV: 375
Watts: 1550
Weight (oz/g): 14.3 (405)



PropLiPoVoltageCurrentWattage Thrust r.p.m.
14x8 7S 29.4V 47A 1,382W 4.8kg 9,570
14x10 7S 29.4V 54A 1,588W 5.6kg 9,300
15x8E 7S 29.4V 52A 1,529W 5.8kg 9,300
15x10E 7S 29.4V 64A 1,882W 6.9kg 9,100
16x8E 7S 29.4V 64A 1,882W 6.7kg 9,000
16x10E 7S 29.4V 71A 2,087W 7.3kg 8,500
16x12E 6S 25.2V 78A 1,966W 6.3kg7,200
17x8E 6S 25.2V 62A 1,562W 5.2kg 7,600



(6S = 6 cell, 7S = 7 cell)

It will probably work good with the OS motor anduse 6 cell 4500 - 5000 mAh capacity and around 25-40C rated Lipo will work.
Prop You can try is APC electric 16x12E, that will give rather good thrust but You may need to experiment to get optimal prop.
ESC You can try for example a Castle Creations Edge 100 ESC (with BEC) and You can combine that with a Scorpion Backup Guard so receiver and servos will still get current if BEC fail or motor LiPo battery fail. You want some margins how much continious current the ESC can handle so even if Your setup will not draw close to 100 amp but probably around 80 amp it is a 20% margin and that is good to have so ESC not get overloaded.

/Bo

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Old 07-17-2013, 06:12 AM
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Default RE: OS Motor OMA-5025-375 .

Thanks. Much appreciated.
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Old 07-17-2013, 06:43 AM
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Default RE: OS Motor OMA-5025-375 .

Those motors are not that similar. If you are asking that question then I would recommend avoiding something that is not a 'drop in replacement' where you have to change batteries, props, etc and start experimenting.

Try the Hacker A50-12S, I would consider that a direct replacement. If you are looking to compare motors, the first two things I look at are kV and weight. kV gives you the rpm - similar kV means similar batteries and prop. Weight is directly related to power handling and of course balance.

With the A50-12S you would use the same prop, same batteries, same everything as suggested in the E-flite setup. You may have to adjust the mounting to get the prop cone to line up right, not sure since the length is missing from the specs. There is a 35g difference in weight, so minor adjustment of battery position to compensate for balance.

And of course Hacker motors are great. E-flite motors are great too, just much less of a selection of models with various kV.

Hacker A50-12S
https://www.aero-model.com/8_164_198...-12S%20V3.html

Weight 345.00 grams
Shaft Diameter 6.00 mm
Shaft Length 0.0000 mm
kV 480
Idle Current 0.00 Amps
Operating Current 70 Amps
Peak Current 90 Amps
Peak Watts 1700
Peak Amps 90.0000
Resistance 0.0000 ohms
Poles 0
Orientation
Motor Diameter 48.00 mm
Motor Length 0.00 mm
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Old 07-17-2013, 07:14 AM
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Default RE: OS Motor OMA-5025-375 .

If you are going to use six cells, I would also look at the Hacker A50-16s with a CC Ice 75. That is what I have in my Miss Wind Bipe and love it. In the air it only pulls about 60 amps with a 16x12 Xoar Wood prop.
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Old 07-17-2013, 08:51 AM
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Default RE: OS Motor OMA-5025-375 .

Quote:
ORIGINAL: RCBruski65

If you are going to use six cells, I would also look at the Hacker A50-16s with a CC Ice 75. That is what I have in my Miss Wind Bipe and love it. In the air it only pulls about 60 amps with a 16x12 Xoar Wood prop.
Just to help the OP:
The Hacker A50-xxS motors are the same size/weight and relatively same power rating. The A50-xxL would be longer and heavier. The motor suggested by RCBruski is a lower kV than the E-flite, so you will get lower RPM. But note he is using a 16x12 instead of the 17x7 as suggested on the E-flite page for the Beast.

The difference between the recommended E-flite motor (or the A50-12S I suggested) and the setup suggested here is sort of like "3D vs Pattern". For Pattern/IMAC flying we like very smooth aerobatic flying with relatively constant speed. In 3D guys prefer large diameter props with less pitch for slow, high alpha maneuvers.

If you really like pattern and want to practice graceful, precise aerobatic flying then RCBruski's suggestion is a good one. Either way you will have a setup that is within the recommended limits of that airplane (power, weight, size, etc). His suggestion is also going to be a little more efficient and give you longer flight times.
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Old 07-17-2013, 04:20 PM
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Default RE: OS Motor OMA-5025-375 .

Hi,

I do not have direct experience with the motor you are considering, but I am using a 5020-490 on a 6lb 330 Extra. The plane flies well behind a 16x12 prop on a 5S battery; however, the prop I ended up using is quite a bit different from what their data sheet recommends. The prop I am using is larger than what they recommended, even so, the current draw is in the 55 amp range so it is within reason. I am pretty happy with the motor so far, it is nice and smooth although it seems to get a little warmer than the AXI it replaced.

The only thing that I do not like about it is the use of a collet type adapter to hold on to the prop. With this much power, I would prefer a bolt on adapter. I would not shy away from the OS motor, but as it has been said before, you might need to play around with props until you find something you are happy with.

Good luck,

Teo
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Old 07-17-2013, 05:17 PM
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Default RE: OS Motor OMA-5025-375 .

Thanks guys for all your advice.

As i said i don't have a lot of experience with electrics so any help is appreciated. With the E flite 60, 470kv not available yet, i am just looking for something to get the plane flying and then maybe switching to the E flite when available.

That's why i initially considered the OS. Looking at the OS specs the weight is about right and it seems to have enough power with the right prop size and i like the bolt on prop adaptor for a model of this size. I have been flying pattern for a long time, so trialing and selecting the appropriate prop goes with the territory. I have no problem with trying props that are not on the manufacturers list either.
OS say the APC 16x10E gives 1966W, so maybe a 17x8 or 18x8, depending on prop clearance, maybe the go. This is working on IC theory but i assume electric is different which would explain previous recommendations of the 16x10 or 16x12.

Is it that the KV is lower than the e flite, a higher pitch prop is needed to get the thrust?

I posted on here because i haven't been able to find any reviews as to how this motor actually performs in the real world. I've found some bits and pieces of info, but nothing substantial. The couple of things i have read is that the OS power specs are a bit high and that the kv is a bit low.

Taking all this into account, my gut feeling is that the OS should be able to fly The Beast reasonably well. The cost of the OS is reasonable as well, so if i went this way and then changed to the E flite it isn't too much cost.

I was just looking at the Hacker range also.

As i like flying pattern, i would fly The Beast for both precision aerobatic flying and 3D.

It's all a bit confusing but i will get my head around it eventually.

Thanks
Scott
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Old 07-17-2013, 07:02 PM
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Default RE: OS Motor OMA-5025-375 .

I think the kV of the OS is too low for 6S. The big problem is you can't find props with more than a 12" pitch with that small of a diameter. You may run out of options and find the airplane flies too slow, and there is nothing you can do about it.

I had that experience with a 210kV motor running on 10S. I know those numbers are used in bigger pattern planes so I thought it would work well 'overpowering' my 1.20 size plane. Well, the big planes run bigger props and up to 14" pitch props. I am still using that motor but have to fly full throttle climbing into a breeze, and have nothing left to after vertical and having to pull/push into the wind.

It is very disappointing - it was my first electric experience and I just want to help others avoid having the same disappointment.

Note the specs for that OS mostly revolve around a 7S pack. It's an odd size, you'd have to make your own from 4S and 3S packs or whatever.
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Old 07-18-2013, 01:49 AM
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Default RE: OS Motor OMA-5025-375 .

Here's some discussion about this O.S. motor:
http://www.rcgroups.com/forums/showt...5#post23228396

IMO, these are excellent motors. In this case the weight and size are close to the recommendation but kv is lower. That means you need a bigger prop to achieve the same performance. For 3D you do not want a very high pitch prop so I'd say a 17" is a good starting point.

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Old 07-18-2013, 05:51 AM
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Default RE: OS Motor OMA-5025-375 .

The kV of the OS and the A50-16s are pretty close (OS slightly more actually) - based on that and the other thread it sounds like you would be OK with 6S and a 10-12 pitch prop. Importantly, RCBruski and the linked thread both are comparing motors on a biplane which is good.

kV and voltage give you nominal RPM. Multiply kV X 3.7v/cell X 6 cells for your peak RPM. So lower kV results in lower rpm, hence a higher pitch prop is needed.
(When you give full power the voltage will drop - you will never have 4.2V/cell going to the motor at high power. There is also efficiency, usually around 88% or so, so you won't reach quite the number you calculate.)

So peak RPM from the E-flite is around 10,400 and peak RPM from the OS is around 8300. 2000 rpm difference is HUGE.

OS makes good stuff. I love their glow engines and just bought their ESC which reports are saying is fairly solid.

If I was going to get the Beast, I personally would be weary of a kV that low for anything other than pattern. It sounds like it will work but you're limited off the bat to 10-12 pitch props. They don't make them bigger, smaller risks flying too slow. Also high pitch props don't bite as well at slower speeds (prop stall) so for 3D they are not preferred.

Just my take - everyone has their own.
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