Water Pump

[Terry PlumridgeParticipant @terryplumridge66794]

Hi all

can anyone recommend a 6-12 volt water pump. I have found the Robbe and Graupner ones, but these are for intermittent use only, not really suitable for a cooling system.

Cheers, Terry.

[Terry PlumridgeParticipant @terryplumridge66794]

[Paul TParticipant @pault84577]

Terry

A quick reply would be a car windscreen washer pump but for a better answer could you tell us what diameter and what length of pipe do you intend to use.

Paul

[Terry PlumridgeParticipant @terryplumridge66794]

Hi Paul

4mm internal dia. silicon tube. Overall length from inlet to outlet approx. 1 metre, passing through a motor cooling coil and an esc cooling plate on the way.

Terry.

[ashley needhamParticipant @ashleyneedham69188]

Terry. What sort of boat is this? usually an external take-off from the prop area is used for water cooling. Fairly failsafe and efficient, and provides more water flow at high speeds (but you know this). Is it too late for this (need to fit a water scoop)?

One of my boats has a prop type scoop and pictures at high speed show a veritable jet of water exiting the coolant outlet, length of tube probably approaching the meter mark. Tube internal diameter less than 4mm.. this seems fairly large to me?

Ashley

Edited By ashley needham on 03/07/2013 21:07:03

[Terry PlumridgeParticipant @terryplumridge66794]

Hi Ashley.

The boat is an Aerokits Sea Commander. It has a Graupner brass water scoop just aft of the prop just about in line with the prop tips. 4mm I.D. tube fits the scoop just right and is necessary for the motor coil O.D. I get flow at high speed of course, but in my opinion a model such as this should not be tearing around the lake at speeds that would require the crew to wear G suits. At closer to scale speeds the boat looks so elegant, but without any flow of cooling water. I would like to see a bit of a dribble even when hardly moving, hence the pump.

Cheers, Terry

[ashley needhamParticipant @ashleyneedham69188]

Terry. If you are not going very fast then it will or should not need cooling. Run it about for a bit at the speeds you like and feel the motor. They can get a bit warm but even moderately hot is ok, but should be touchable. Anything hotter than that, at "normal" running speeds will need a pump but to be honest this should not be the case in your boat and perhaps this might point to the motor being overloaded ? Ashley

[Terry PlumridgeParticipant @terryplumridge66794]

Ashley.

Looking for a pump mainly to give the model some extra authenticity ie "bilge pump running, even when motionless" sort of thing. But I think I have the answer. I am one of those people that never throw anything away if it looks at all useful. In my bits box I have found a small piston pump driven by an electric motor, it came out of an Oral B dental hygiene gadget. Need to test it a bit before putting in the boat, but it looks perfect for the job, more than enough pressure and the output even "pulses" just like a bilge pump.

Cheers, Terry.

[ashley needhamParticipant @ashleyneedham69188]

Terry, sound just the ticket, you may just be able to reduce the battery voltage to get a really convincing slow pulse.

A pump of any other sort would likely produce much too much water and need some work to reduce the flow, and then overheat due to the restrictions!.It would probably be a bit whizzy-noisy as well.

Ashley

[Paul TParticipant @pault84577]

For water cooling my larger IC engines I use a car windscreen washer pump running on 3v instead of 12v with 6mm tube this produces a suitable flow to cool the engine without the model looking as though it has a fire hose squirting out of its stern.

Paul

Sorry Ashley for banging on again

[Terry PlumridgeParticipant @terryplumridge66794]

Hi Paul,

you've got me thinking now. When they say a pump is for intermittent use only are they referring to the motor or the pump mechanics? If it is the motor then perhaps reducing the supply voltage will, or may, increase the duty cycle to 20 or 30 minutes continuous use. All thoughts welcome.

Cheers, Terry.

[ashley needhamParticipant @ashleyneedham69188]

terry. Guessing here, but I would have though a small electric motor would run for hours no probs unless it was straining and getting hot. My bet is the undoubtably crude pump arrangememnt, spindles running direct in the casing plastic and so on. Of course this is perfectly adequate for intermittant use, as designed, but..

Pauls wheeze, and yes he does bang on about i/c , should assist immesurably with the longevity of the pump (running pump on a lesser voltage).

Ashl;ey

[Paul TParticipant @pault84577]

Hello Terry

The term 'Intermittent Use Only' in my experience means that the pump can not be depended upon to work continually. i.e. a washing machine pump is intermittent as it only runs when the machine needs emptying but the water pump on a car engine runs consistently whilst the engine is running.

As you surmise it is probably due to the inability of the pumps mechanics to cope with the constant work load.

I agree with your theory of reducing the voltage to increase the duty cycle as this is what I do (although I drop the voltage to reduce the flow rate rather than extend the pumps life span)

Let us know how you get on

All the best

Paul

Ashley: You are correct, I do wheeze as amongst my many ailments I also suffer from asthma, although I don't know how you figured it out.

Edited By Paul T on 07/07/2013 15:45:33

[ashley needhamParticipant @ashleyneedham69188]

Paul, Ah, not as silly as my picture makes out !!

Everyone; What about using an aquarium pump?? they work continually forever, and would probably work ok with a large bore system (they are more about flow capacity rather than pressure). Just not sure if they are all mains powered..?

Ashley

[Terry PlumridgeParticipant @terryplumridge66794]

Hi Guys,

Have sourced a pump from Prestwich Model Boats, (good service from them, 4 quid p&p to Austria can't be bad). 12 volt motor running on 6 produces the effect that I am looking for. The pump is, or looks like, a Graupner. Just remains to see how long it will last!!

Cheers, Terry

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