Cermark speed 480 7.2v- 9.6v motor ?

[Andris Golts]

Hi all last weekend at the Toledo show i picked up 4 of these motors still in there original packaging at the swap shop for $5 i was thinking of installing one in my 16'' hydro weights 12 oz's on 2s lipo . Im guessing these motors have been off the market for a decade or so.What size prop would be a good starting point? Regards Andris Golts.

[NativePaul]

Have you got the brushed ESC for it already? If not, I wouldn't be investing in them.

While silver can brushed motors still have their place, a hydroplane is not one of them. That place is scale models that spend long periods of time at very low throttle (where brushless motors are inefficient), and wheeled crawlers that need high torque at zero RPM (where brushless ESCs struggle to work out which winding to activate in order to spin the motor in the right direction until the motor is moving).

A can 480 is good for about 15A, which seems OK for a 16" hydro, I would prefer around 20A on 2s, which is easy to do with brushless. However brushed motors and especially can motors are a lot less efficient. The best can motors (made by Sagami in Japan) were 50-60% efficient and Chinese Mabuchi motors like the Cermark were 40-50% efficient. Whereas the best brushless motors will be in the low 90s% efficient, and the worst Chinesium crap will be in the 70s. If we compare your 15A Cermark setup to a small budget brushless setup in terms of power output there is a big difference, 7.2V x 15A / 45% =48.6W but 7.2V x 20A / 80% = 115W, there is well over double the power available at the prop, and the brushless motor will also run much cooler.

The Brushed 480 also weighs about an ounce more than a 400 size brushless that I would suggest for that size hydroplane.

This is no great hardship, but brushed can motors have holes in the can, and possibly a flux ring so you cant fit a water jacket, you will probably have to wind up an alloy tube around a mandrel slightly smaller than the motor, to make a cooling coil for it, unless you can find a coil for sale.

Back when we ran minis on can motors the boats were only 12-13" long, and we ran 4.8v speed 400s which were capable of about 14A on 4 round cells and 27mm props, a pretty different setup, but I would guess that if built as light as possible and designed well it would be possible to get a Cermark 480 powered hydroplane up on plane.

I haven't used that motor, a quick search didn't bring up a KV for it, and having a 7.2-9.6v range whereas all the can motors I ran had a single voltage rating so I cant compare them, makes it impossible for me to suggest a prop size, start with as small as you can get and work your way up checking for heat each time. I would use a m4 threaded shaft and buy Graupner 2318 props from 29mm up, as they are great props at this power level, don't need balancing and are only $5 each from OSE, which gives you the most amount of props to try for the minimum investment of time and money.

[Andris Golts]

480

Have you got the brushed ESC for it already? If not, I wouldn't be investing in them.

While silver can brushed motors still have their place, a hydroplane is not one of them. That place is scale models that spend long periods of time at very low throttle (where brushless motors are inefficient), and wheeled crawlers that need high torque at zero RPM (where brushless ESCs struggle to work out which winding to activate in order to spin the motor in the right direction until the motor is moving).

A can 480 is good for about 15A, which seems OK for a 16" hydro, I would prefer around 20A on 2s, which is easy to do with brushless. However brushed motors and especially can motors are a lot less efficient. The best can motors (made by Sagami in Japan) were 50-60% efficient and Chinese Mabuchi motors like the Cermark were 40-50% efficient. Whereas the best brushless motors will be in the low 90s% efficient, and the worst Chinesium crap will be in the 70s. If we compare your 15A Cermark setup to a small budget brushless setup in terms of power output there is a big difference, 7.2V x 15A / 45% =48.6W but 7.2V x 20A / 80% = 115W, there is well over double the power available at the prop, and the brushless motor will also run much cooler.

The Brushed 480 also weighs about an ounce more than a 400 size brushless that I would suggest for that size hydroplane.

This is no great hardship, but brushed can motors have holes in the can, and possibly a flux ring so you cant fit a water jacket, you will probably have to wind up an alloy tube around a mandrel slightly smaller than the motor, to make a cooling coil for it, unless you can find a coil for sale.

Back when we ran minis on can motors the boats were only 12-13" long, and we ran 4.8v speed 400s which were capable of about 14A on 4 round cells and 27mm props, a pretty different setup, but I would guess that if built as light as possible and designed well it would be possible to get a Cermark 480 powered hydroplane up on plane.

I haven't used that motor, a quick search didn't bring up a KV for it, and having a 7.2-9.6v range whereas all the can motors I ran had a single voltage rating so I cant compare them, makes it impossible for me to suggest a prop size, start with as small as you can get and work your way up checking for heat each time. I would use a m4 threaded shaft and buy Graupner 2318 props from 29mm up, as they are great props at this power level, don't need balancing and are only $5 each from OSE, which gives you the most amount of props to try for the minimum investment of time and money.

Hi Paul i have a Electric Fly 25 amp brushed esc. Regards Andris Golts.

[NativePaul]

Nothing to lose then. You may as well give it a go and see if you can find a prop that will make it get up and boogie, whilst keeping the temps reasonable.

Electric Fly huh, Do you come from a flying background? If you have a tacho and a voltmeter you can work out the KV, then we can estimate the prop size you could use.

[ray schrauwen]

Make a quad drive kick arse mono.



You'll need at least 2 escs.

[Andris Golts]

Hi Paul thanks for the great info i have a digital volt meter but no tacho i have not flown since the late 1970's just designing and building r/c boats since 1977. Regards Andris.