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Author Topic: what have I done wrong ??  (Read 7857 times)

CJ

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Re: what have I done wrong ??
« Reply #25 on: July 02, 2012, 11:15:23 AM »

mmmmm, cheers....now there is an idea I hadn't thought of, although not sure where I can mount or the weight involved...might be a last ditch attemp solution though that is worth a try, will try and bore out the intake, some larger i/d tube and a smaller prop first and see what happens. Can't quite work out what the issue is though  {:-{

CJ
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Circlip

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Re: what have I done wrong ??
« Reply #26 on: July 02, 2012, 03:26:50 PM »

Perhaps it's an optical conclusion, but referring to your photos in post #16, the pickup tube seems to be too long and too far away from the prop. Back in the Diesel days, we had the hole in the pickup tube fully covered by the tip of the prop and a clearance of about 1/8" (3mm) between the tube and the rear face of the prop.

  Ref. to fine tuning was due to being able to see the output rate from the cooling outlet with the thing in the barf. Wersent possible wiv a diesel as Mummy used to get really annoyed with the brown ring round the inside of the bath.   :embarrassed:

   Regards   Ian.
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CJ

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Re: what have I done wrong ??
« Reply #27 on: July 02, 2012, 06:26:38 PM »

Ian,

Cheers for that, yeah may have a point well made, tommorows job is to work on the pickup so will take that on board, am hoping new tubing will have arrived too with smaller blade that will assist the motor not getting so hot and also make the tip being more in line as suggested.

Will see how we get on !!

Cheers  :-))

CJ
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CJ

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Re: what have I done wrong ??
« Reply #28 on: July 16, 2012, 03:58:29 PM »

Thank you Martin for the chat - everything taken on board, new inlet location, sharper angle on the inlet, thicker tubing and re-routed shorter and dumped in the bath for a splash....





I do seem to now have a steady flow through, also now running a 30mm X prop, once all this rain stops I will get her out on a run and see if she can keep her temperature down!!

Thanks all for the comments and help!

CJ


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ACTion

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Re: what have I done wrong ??
« Reply #29 on: July 16, 2012, 04:10:24 PM »

CJ
That looks like a helluva big boat for such a small motor and prop. What's the model?
DM
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CJ

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Re: what have I done wrong ??
« Reply #30 on: July 16, 2012, 04:25:23 PM »

Hi Dave,

It's a Robbe PT15 hull, http://www.modelboatmayhem.co.uk/forum/index.php?topic=37569.0





She's on a Deans Marine Kestral and 35mm X prop - not tested at the moment, she was running a 55mm X prop and was planning really nicely, unfortunately you couldn't touch her for upto 30 mins after - Just dabbling with a few things as the water cooling wasn't working, I am thinking I might replace the motor too as I think I may have cooked it  :embarrassed:

Why - any thoughts ??

CJ
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Guy Bagley

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Re: what have I done wrong ??
« Reply #31 on: July 16, 2012, 05:06:43 PM »

bring her down to black park one sunday morning, we'll get to the bottom of this once an for all .....we can bring different props and see what effect that has to current draw
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all in all its just another brick in the wall......

ACTion

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Re: what have I done wrong ??
« Reply #32 on: July 16, 2012, 05:57:13 PM »

Why - any thoughts ??
CJ

The usual reason for an overheating motor is either the wrong motor, the wrong prop, the wrong voltage - or perm any two and then add one for fun!
I can't find any current listing for the Robbe PT15 but it looks at least three feet long from your pictures. On a single prop I wouldn't run anything less than a Speed 700 in such a model. An X55 is altogether too much for any brushed motor on the sensible side of a Speed 900BB. I'm not surprised that the poor little Deans motor is getting worked up - it's like putting a 1400cc petrol engine into a quarry truck and then trying to drive it up a wall in fifth gear.
Unless you have a burning desire to go brushless then I would say to remove said Kestral, fit a Speed 700 9.6v motor (#G3308) and run something like a 40mm 3-blade brass prop.
Suit yourself, as someone once said.
DM
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CJ

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Re: what have I done wrong ??
« Reply #33 on: July 16, 2012, 07:00:04 PM »

Thanks for the offer Guy, I might just do that very soon - haven't you got an event planned in September ??

I'm not surprised that the poor little Deans motor is getting worked up - it's like putting a 1400cc petrol engine into a quarry truck and then trying to drive it up a wall in fifth gear.

 :embarrassed: :embarrassed: Yeah OK, I get your point.....hey it's all trial and error. The parts was recommended elsewhere although I have mixed and matched and have to say not massively impressed with the Deans motor.

Another member has just mailed me the Speed 700 with a 40mm X prop setup so will try that  :-))
Hey - this is surely part of the fun, models are never finished are they  :}

Cheers

CJ
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john44

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Re: what have I done wrong ??
« Reply #34 on: July 16, 2012, 08:24:44 PM »

Hi guys, the PT15 is 34.5" long with a 9" beam.
I run mine using a car fan motor. It never gets hot.

john
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Guy Bagley

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Re: what have I done wrong ??
« Reply #35 on: July 16, 2012, 09:41:46 PM »

Thanks for the offer Guy, I might just do that very soon - haven't you got an event planned in September ??




oh yes, all welcome -
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CJ

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Re: what have I done wrong ??
« Reply #36 on: July 17, 2012, 12:40:03 PM »

I would say to remove said Kestral, fit a Speed 700 9.6v motor (#G3308)

Anybody any ideas where I might get one, seem to be unavailable everywhere - or an alternative suggestion Dave ??

Cheers

CJ
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CJ

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Re: what have I done wrong ??
« Reply #37 on: July 19, 2012, 11:04:48 PM »

OK, so speed 700 unavailable everywhere  >:-o so gone for the Speed 600BB   %%

All water cooling work complete and new motor now fitted and she sounds nice, will try and get some testing done on Saturday with various props ready for the sun to shine all day on Sunday and get some proper playtime in  :-))

CJ
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CJ

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Re: what have I done wrong ??
« Reply #38 on: July 21, 2012, 12:51:18 PM »

 >>:-( OK, so flippin water cooling still not working  >>:-( , I am thinking that whe is planing just too much to actually get any water through her !!

Either way it appears the new setup means it is not needed anyway, the new Graupner Speed 600BB and a 40mm X Prop means she goes like stink, planes at over two thirds and she still stays cool after a 30 min runtime - Will try and play a bit more as I hate the fact it's beaten me but will probably end up with the filler out  {:-{



CJ  :-))
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