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Author Topic: humming bird motor  (Read 262 times)

nemesis

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humming bird motor
« on: September 24, 2020, 04:32:05 PM »

I have unearthed a Humming bird electric motor, by the look of it, it had been in a boat at some stage. Can anybody give me an idea of the Spec, ie volts, amps and rpm. thank you, nemesis
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tonyH

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Re: humming bird motor
« Reply #1 on: September 24, 2020, 05:28:25 PM »

MFA Hummingbird 15 or 20. 540/550 size. 9.6volts. As apparently recommended for the MFA Piranha back in the 2010's
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tonyH

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Re: humming bird motor
« Reply #2 on: September 24, 2020, 06:04:19 PM »

Just found.Hummingbird 20 - 1380 revs per volt. Allegedly 1.3 amps and same output as 2cc diesel?
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malcolmfrary

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Re: humming bird motor
« Reply #3 on: September 25, 2020, 09:54:46 AM »

Just found.Hummingbird 20 - 1380 revs per volt. Allegedly 1.3 amps and same output as 2cc diesel?
Depends on the state of tune of the 2cc motor. 
Not a diesel, but a 2.5HP outboard (not a diesel, but still....) gives about 1/20 HP per cc, so a 2cc motor giving out the same rate would be about the same as an electric motor running on 12 volts and pulling about 7 amps under load.  750W=1HP, 750/20=37.5watts per cc, call it 80 watts to equal 2cc.  A 7 amp (under load) motor unloaded would should be a lot less.  What would the Hummingbird pull when working for its living rather than just spinning itself?
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Tug Fanatic

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Re: humming bird motor
« Reply #4 on: September 25, 2020, 10:29:55 AM »

Depends on the state of tune of the 2cc motor. 
Not a diesel, but a 2.5HP outboard (not a diesel, but still....) gives about 1/20 HP per cc, so a 2cc motor giving out the same rate would be about the same as an electric motor running on 12 volts and pulling about 7 amps under load.  750W=1HP, 750/20=37.5watts per cc, call it 80 watts to equal 2cc.  A 7 amp (under load) motor unloaded would should be a lot less.  What would the Hummingbird pull when working for its living rather than just spinning itself?

I am not sure that this is right. As brushed electric motors rarely run at more than 60% efficient (& often a lot less) you would need nearly double your 7 amps on 12v so lets call it 150 watts.

Neither am I sure that you can extrapolate a full sized petrol outboard to give you results for a model motor which could be in a much higher state of tune.

Am I wrong?
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tonyH

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Re: humming bird motor
« Reply #5 on: September 25, 2020, 11:01:27 AM »

I agree with a motor under load but assume the figure are no-load. I had a Hummingbird years ago but I can't remember for the life of me what it was in or how it went.
The numbers came from this and I can claim absolutely no accuracy! www.slkelectronics.com/ecalc/motors.htm
Seems that they were used a lot in e-flight so would/should be quite revvy possibly?
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tr7v8

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Re: humming bird motor
« Reply #6 on: September 25, 2020, 11:04:18 AM »

I am not sure that this is right. As brushed electric motors rarely run at more than 60% efficient (& often a lot less) you would need nearly double your 7 amps on 12v so lets call it 150 watts.

Neither am I sure that you can extrapolate a full sized petrol outboard to give you results for a model motor which could be in a much higher state of tune.

Am I wrong?
No perfectly correct. Assuming a modern Schnurle ported 2cc glow, max would be 0.25 to 0.3BHP which is around 150BHP per litre (very high by full size standards), a sport engine or an old diesel would be less. So .25BHP is 0.746  x .25 is .186kW or 186Watts. At 9.6V that would be 19.3Amps assuming 100% efficiency. At 60% or so it would be 32Amps & 309Watts. That needs a reasonable size brushless to give that output. And would probably be on a higher voltage supply for that.
This on 14.4V would work.
https://www.4-max.co.uk/po-3535-870.html
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nemesis

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Re: humming bird motor
« Reply #7 on: September 25, 2020, 05:54:18 PM »

Thank you all for the info, yes it was for model flight,it revs like a banshee, thanks again, nemesis
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Andyn

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Re: humming bird motor
« Reply #8 on: September 25, 2020, 06:34:35 PM »

No perfectly correct. Assuming a modern Schnurle ported 2cc glow, max would be 0.25 to 0.3BHP which is around 150BHP per litre (very high by full size standards), a sport engine or an old diesel would be less. So .25BHP is 0.746  x .25 is .186kW or 186Watts. At 9.6V that would be 19.3Amps assuming 100% efficiency. At 60% or so it would be 32Amps & 309Watts. That needs a reasonable size brushless to give that output. And would probably be on a higher voltage supply for that.
This on 14.4V would work.
https://www.4-max.co.uk/po-3535-870.html
Not sure where you pulled those numbers from, but a modern 2cc glow certainly isn't turning less than a horsepower {-)
A 3.5cc glow, untuned, is around 3bhp.
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unbuiltnautilus

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Re: humming bird motor
« Reply #9 on: September 25, 2020, 07:50:07 PM »

Hummingbird 15 was a Mabuchi 540, Hummingbird 20 was a Mabuchi 550 ( more torque, less revs, longer can ), and a Hummingbird 30 was a Mabuchi 750, loads of amps.. mostly useless!!
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