motors

[anthony james 4Participant @anthonyjames4]

overheating

[anthony james 4Participant @anthonyjames4]

My friend has a 34 inch huntsman, fitted with a graupner speed 600, 25 amp ESC, running on 8.4 battery with a 35mm “s” prop.

 

Although the boat goes very well, (a little bit fast at times), the motor overheats after some five mintes and the esc is warm to the touch.

After ten mintes the motor is too hotb to touch, and the esc is decidely warm.

This was the recommended combination by various peple.

 

what exactly has “nominal” mean. I interprate as “th ideal”

 

Any ideas, apart rom watercooling gratefully received.

[Colin BishopModerator @colinbishop34627]

Not really my area of expertise but your friend could try using a smaller prop which would take the load off the motor and at the same time trim the full speed a bit. That would seem to be the obvious first option.

 

Colin

[Gareth JonesParticipant @garethjones79649]

Can you be a bit more specific as to which Speed 600 motor is fitted? There are lots of different variations on the same basic 600 size, some are optimised to run at high rpm and are not really suited to direct drives for boat propellers. It would help if you could quote the Graupner part number then we can identify the performance characteristics of this particular motor.

 

Almost certainly the propeller is too large for the motor being used, but I have not operated this particular model so I am not sure whether it would be best to change the motor or prop.

[ashley needhamParticipant @ashleyneedham69188]

I would have thought that a speed 600 would be ok on a 35mm “s” prop, but there again, as Gareth says, there are loads of different 600s about.

 

The Graupner “ECO speed 600” I have in the Toyboata running on 7.2v and driving not only a 35mm 3 blade brass prop but the worm drive to the back wheels only gets warm after a good thrashing (its the only way the lad drives it) .Do we take it that everything is free running and lined up ok etc?

 

Ashley

[anthony james 4Participant @anthonyjames4]

Many thanks guys, the motor is a “speed 600” not eco, turbo or race.

WE are now thinking of a 6volt dry sell battery to see what comes

and we did try running at half power to no avail.

 

WHat’s next ? Recycle bin??

[ashley needhamParticipant @ashleyneedham69188]

no other markings?? voltage or whatever? try a 32.5 or 30mm “s”prop, or even a 35mm brass 3-blade one. Any speed 600 should turn one of those without getting hot i would have thought..

 

Is it definitely an S prop and not an X variety?

 

Ashley

[Dave MilbournParticipant @davemilbourn48782]

The 34″ Huntsman was designed for a 1BHP glowplug (aka “nitro”) motor, and there is no way that a Speed 600 will put out that amount of power. I don’t think that changing the prop will have much effect; I would change the motor if it were my boat.

I suggest a Speed 700BB would be more appropriate, although one member of this Forum uses a Speed 900 clone on 18 volts! Over to you, Barzo…………..

Dave M

[Queequeg QuintParticipant @queequegquint38270]

I say gear it down. When I first ran my Orca, I used a 550 motor direct driving a 45mm 4-blade brass prop, at 8.4volts. The motor burned out in about 5 minutes, but man, the boat sure did fly!

 

I kept the 45mm prop and switched to a MFA Como 500 geared down 2.5:1 (I think it’s now known as the 919D series), running on 12volt 7 AH SLA battery. One time, I ran it full throttle for almost one hour. Upon returning to shore, I opened the hood and a cloud of white smoke came out of the hull! That motor was hot! The plastic gearbox cover also melted into the gears!

 

So, I got a new MFA Como 500 motor, 2.5:1, and added a 12 volt mini cooling fan (just in case). I’ve been running the thing for over a year now with no problem.

[TelstarParticipant @telstar]

Hi Anthony

“Nominal” value is not the ideal value See here

In this case it is the voltage at which other data is quoted, ie no-load current or motor rpm. These values change with applied voltage so are referred to a ‘nominal’ value.

The chart is ‘borrowed’ from Graupner website and is for the Speed 600 motor, it gives nominal V 9,6v but operating range as 7.4 to 10v

Operating voltage range	7,4…10	V
Blockierstromaufnahme	58	A
Diameter	35,8	mm
Free shaft length	8,7	mm
Case length	57	mm
All-up weight, approx.	195	g
Maximum efficiency	75	%
No-load current drain (A)	1	A
Charging rate at max. efficiency	7	A
Permissible motor direction	R und L
No-load speed	14500	U/min
Nominal voltage	9,6	V
Shaft diameter	8,7	mm

 

To reduce heating reduce prop size, but not voltage. If anything I would reduce the prop say 30X and up the volts to 10 or possibly 12 v

 

Cheers Tom

[ashley needhamParticipant @ashleyneedham69188]

As Dave M says, bung a bigger motor in.

 

Sorry to harp on about MFA motors, as I do, but a good old Torpedo 850 on 12v would give good performance on an X50 prop all day and only get warm.

 

I don`t doubt of course that better and more economical performance could be obtained by using an ?motor at ?V and on an ? prop. but I don`t know about those!!

 

Ashley

[TelstarParticipant @telstar]

Hi If Anthony is happy with the present performance

‘Although the boat goes very well, (a little bit fast at times)’ (first post on this thread), why bung in a bigger motor, another £25.

 

As for the MFA Torpedo 850 altho a nice motor, it does not (theoretically) provide as much power as a Graupner speed 600. However the speed 600 is designed to run at much higher RPM, and as such needs to have a smaller prop to allow it to generate the higher power. The Torpedo 850 is a much lower revving motor but has a high torque, as such it is much happier with bigger props.

 

Its horses for courses,

 

Having spent time looking at some of the motor performance evaluation programs (where you can predict the motors characteristics) and proved to my own satisfaction how effective they are(or are not) My winter project is to play with some props and try to evaluate their characteristics in an efford to be able to answer

‘using an ?motor at ?V and on an ? prop’ for best results be it efficiency or performance.

I’m not sure if a 50 x prop at 1000rpm is better than a 40 s at 2500rpm, but i’m going to try to devise some test to see which is which.

 

OFF soapbox Tom

 

[ashley needhamParticipant @ashleyneedham69188]

I would have thought that you want not only power per se, but speed of the water “jet-stream” coming off the prop to go really fast.

 

At the pond I have been amazed at various times by the speed of boats with tiny props, but which are revving to the devil in the process.

 

Good luck with any tests. I only know that holding on to the Fantome is a struggle at the quay side, such is the pull of it at full throttle (2x 800, 12v, 50x props) but its not particularly fast,

 

Ashley

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