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[Nick-R]

I have built an Aeronaut Queen with a brushless motor fitted with a cooling coil plus a water cooled speed controller.  There is a water pick up scoop just behind the prop connected by silicon tubing first to the speed controller thence to the motor then back to an outlet on the transom.  Try what I will, I can’t get the set up to not airlock/water to flow.


 I have tried moving the position of the controller but to no avail.  There is obviously back pressure also as despite there being a circlip connecting the tubing to the scoop, it leaks there.  I can blow through the system and feel air coming through the transom outlet.  I have also gravity fed both the controller and motor and water flows ok so no blockages.  Water does not reach as far as the controller.


Anyone?

[Backerther]

Hi
You have a nice cabin cruiser boat, don't you.?
I think normal, usual and traditional style of water cool set-up that you said(though not shown here by pics) or I did in the pics below would be less trouble or trouble-free on condition that you had it properly set and had her run at an appropriate speed.
You did not touch upon the operation itself. As you may know a certain level of speed is indispensable to suck the water securely into the tubing against the back pressure. I know back pressure is rather hard in the tubing since every time I finished the boating of a day, I made it a practise to blow the tubing thoroughly to drive the water out for cleaning and anti-rusting.   Your trouble I feel may not be so difficult to overcome...from my experience...


1;General layout
2; Attention to the tubing around the ESC. It's one-way pass style, not U-turn pass style for smooth flow of water using Y-pipes.
3;Sufficient drain was achieved even at half throttle.


I'd like to know/see how you set the tubing and other stuff, if possible......
"Seeing is believing"..!!

[Circlip]

Old school water cooling. Scoop(?) should be as close to the prop as possible with the hole just inside the prop tip arc so you're getting the maximum 'Ram' effect of water being pushed through the system. Pumps are fine but old school is free.


 Regards   Ian

[JimG]

 I have tried moving the position of the controller but to no avail.  There is obviously back pressure also as despite there being a circlip connecting the tubing to the scoop, it leaks there.  I can blow through the system and feel air coming through the transom outlet.  I have also gravity fed both the controller and motor and water flows ok so no blockages.  Water does not reach as far as the controller.


Anyone?

not sure what you mean by a circlip connecting the tube to the scoop? Normally the tube is pushed over the end of the scoop outlet and if it is needed for security a wire is wrapped twice round the tube then the ends twisted to tighten it, don't use cable ties as they are not completely round when tightened and can leak.
Jim

[Dave_S.]

While I agree that some means of retaining the water cooling tube everywhere where it fits onto a metal or plastic joiner or nipple, in my experience, wire is not a great idea as tends to cut through the tubing. Assuming you are using a flexible silicon tubing, the best method I have used to secure it is to cut a small (1/16"-3/32") slice of the same tubing, and using needle nosed pliers, slip it over the tube, then push the tube onto whatever is needed and slide the ring of tubing back over the connector. That will hold it tightly in place and won't cut through the flexible tubing and fill your boat with water.

[Nick-R]

Ok so here are a couple of photos.  Re attaching to the scoop, the tubing is pushed on and then has an automotive spring clip securing it in an attempt to stop leakage.  Before the circlip, water was being forced past the tubing/scoop joint which suggests to me there is plenty of water pressure out of the scoop.  You will see there is a fair amount of resin in the stern compartment as originally, I thought I had a hull leakage issue.

[SteamboatPhil]

Your scop has a sharp angle, if you can cut it so you get the maximum intake that may help maybe at least 60 degrees

[Nick-R]

Your scop has a sharp angle, if you can cut it so you get the maximum intake that may help maybe at least 60 degrees

I don’t think the issue is how much water the scoop is catching as, as I have said, water was being forced past the joint between the scoop and silicon tubing.  That must imply decent water pressure?  I may try disconnecting from the ESP and putting hose over the side.
(In the bath!)  If that works, reconnect ESP and do same with disconnected motor feed - just to establish where the lock is.

[JimG]

It looks like you are taking the outlet to the transom, if so you have a long length of tubing which might give some back pressure. Try taking the outlet to the side of the hull beside the motor thus reducing the lenght of tube.
Jim

[Backerther]

Hi
Juding from your description and pics attached, I suppose you haven't sailed her actually yet on the water at all...?
And your issue was concluded from only bath test that hardly simulates actual sailing conditions in terms of water pressure
 required to go into the water inlet scoop....   I never believe in the bath test in this point from my experience.
In order to get sufficient water pressure into the scoop, a hull speed itself is indispensable.
I suppose you had better sail her actually on the water at present configuration first at a bit fast speed.
Unless a nice result of drain was fulfilled, you should change the water outlet to the nearest starboard side which might perhaps reduce the back pressure.
I think the adequate speed of hull and configuration of tubing is essential to get a good drain. 
Overcome the back pressure by hull speed and shorter tubing.!!!  From my empirical point of view about water cooling for RC boat...


Pics are from one of my boats. Even this boat does not drain in the bath test at all except a litte amount of water sucking.!!


The last pic is the latest style of water inlet scoops.  Two hole system...one for the motor, the other for ESC draining both sides of hull. For a quicker and more effective cooling of the stuff.!! For even at maximum speed continuous sailing.!

[Circlip]

 Sorry Backearther but had that been the case in the glory days of I/C powered toys, there would have been lots of seized engines. One can hardly describe a vertical piece of tubing with an angled cut on its face as a 'Scoop', Having said that, if the system has been bath tested and can highlight leaks, despite the incorrect positioning of the pickup for maximum efficiency, suggests it's working. Forward movement of the hull should never be the deciding factor for an efficient cooling system, propeller rotation yes, hull transit no.
  Correct scoop shape can easily be seen on the 'Old' adverts for Keil Kraft and others of the bent tube variety and NOT the plastic molded 'Cosmetic' sticks eventually offered (bout same time as the Hewco rubbish appeared). Positioning of said scoop can be obtained from many books devoted to toy boat building, easily found with a few keystrokes. Both drive and cooling 'discussions' have been extensively covered on this forum, befriend "Search".
   Strangely enough, in all the years of playing with toy boats with 'proper' drive units, push fits of the standard (NON silly cone) plastic tubing from the pickup to the ingine to the outlet NEVER required an extra mechanical restraint.


  Regards  Ian.

[Nick-R]

I have only taken the hobby back up in the last year or two after a lifetime away from it, but back in the day, I built amongst other things, a few fast planing boats powered by IC engines and these required cooling laid out similarly to what I am trying to do now, albeit solely to the engine as opposed to the daisy chained set up in my current boat.  I never had any issues with these and always took the outlet back to the transom along with the exhaust.


Backerther is correct in that I have not run the boat for real, only in the bath, because I want the leakage/cooling problem sorted first.  With respect, I do not really accept that the forward motion of the boat is required to make the cooling system work.  The propeller imparts motion to the boat by creating a strong flow of water and if the scoop is correctly positioned in that flow of water, it should work OK even in the bath!  In this case, that is evidenced by the fact that water is being forced out of the joint where the silicon tubing is pushed on to the inboard side of the scoop.  I conclude that it must be back pressure so its back to the bath and a bit of experimentation disconnecting tubes to find where the blockage is.  I have already checked that I can gravity feed both the motor and ESC and both flow without issue so I think it must be simply airlocking somewhere!


I have even toyed with inserting a bleed valve but have been unable to find such a thing which will fit the silicon tubing.  I may also try inserting some solid piping to replace long runs of tubing.


I will keep everyone posted

[John W E]

hi there


I do agree with Sir Circlip on this one mind.   It looks as though you may have positioned the scoop in the low pressure part of the propellor arc  - it could be on the incorrect side.   Here are a couple of photographs for Ian to drool upon - of the good old days of sore fingers - tryng to start an IC engine with a bootlace and an old fashioned water scoop - aye the good old days I think when KeilKraft used to sell some good fittings for a decent price.   

[Nick-R]

I remember the days of sore fingers well, not to mention boats needing strong hulls as you gripped them between your knees whilst working the starting cord!  I also remember finding out the hard way that the neophrene tubing we used back then could handle diesel exhausts but not glow plug engines.  Made a bit of a mess of the interior of my Aerokits Swordsman.  I also stove in the bow of the same boat by having single channel code finger trouble resulting in full throttle just as I approached the (rocky) edge of the pond when attempting a minor course correction bringing her back in.


You mention Keilcraft.  Their ezebuild range of balsa boats was my introduction to working model boats and transition away from Airfix do nothing plastic kits.

[Circlip]

Felt the flinch on the first fingers of both hands looking at that picture John, our choice of whip being braided nylon. Castor Oil soothing the grooves but did lead to the three day stink, albeit on soft hands, and yes, never needed a battery for engine starting. Picture should be added as a permanent reference for 'conventional' hulls, screamers are something else.


  Regards  Ian.

[Nick-R]

As a postscript, in my Aeronaut Queen I had fitted a Raboesch brass water scoop, piped by silicon tubing to the ESC and looped from there to the water cooling jacket on the motor then back out through the transom.  See pics in post above.


I tried shifting the ESC to various different positions thinking it was the culprit causing the airlock but to no avail.  I have therefore now removed the brass scoop (with some difficulty due to having sealed it all with epoxy resin!!!). I replaced it with the nylon scoop in picture below and now the transom outlet scoots water out to about 3 or 4 inches before it hits the water again.  Better shaped larger area scoop placed slightly lower so it is directly in the prop wash!


My problem now is that all the silicon tubing unions leak - at the scoop, at the ESC and at the motor.  I have been unable to find miniature jubilee clips anywhere but have tried the sort of squeeze together spring clips but these are useless.  Anyone know a source of suitable miniature jubilee clips or have an alternative solution?

[tonyH]

Possibly medical pinch clips? down to about 4mm.

[Martin (Admin)]

 
You can find these very neat ones on ebay ....

Water Cooling Inlet Pickup Bottom Dual Water Nipple Nozzle - https://shorturl.at/ai4db
 
 
       
 
 

[mrlownotes]

I'd suggest twisting solid copper wire, maybe 1mm.
I haven't tried it myself. I just thought of the wire twists we use on freezer bags.
Maybe you can twist as much as you like until the leak stops.
If it works the fix is 'cheap as chips'

[Nick-R]

I found some stainless jubilee clips on Amazon which have a stated minimum diameter of 6mm.  The tubing itself has an exterior diameter of 6mm but this increases to 7-7.5mm when squeezed over the nipple.  I am hoping therefore that these jubilee clips will go tight enough to do the business!


Will report after trying this.

[T888]

Hi,


I’ve used these on my Miss Circus Circus cooling tube.
10 plated steel spring clips for 6mm to 7mm od silicone tubing

[HMS Invisible]

...  Anyone know a source of suitable miniature jubilee clips or have an alternative solution?

Polyester tube or the tube that comes with windscreen wash pumps will not expand under the same pressure as silicone. A no-cost idea that will likely work is thick heatshrink or two or more layers of cheap heatshrink tube just extending past the length of the nipple.

[Circlip]

Ex Oxygen mask tubing is ideal too. Why silly cone?


 Regards  Ian.

[HMS Invisible]

...and then stretched o-rings pinching the tube on the outside might work & self amalgamating tape will make a seal.