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[darrencuk]

Hi guys I'm building my own jet boat out of 3mm ply I have a graupner mini jet drive unit that can run a 540 sized motor but I'm going to run a 3000kv brushless motor the impeller in the unit is 19mm I'm wondering will this cope okay any pointers towards this would be help full

[john s 2]

Two things come to mind. One is cavitation caused by high speed and the other is trying to pass too much water through a confined space. I have some jet units. It will be interesting to read other members comments. John. 

[pompebled]

Hi Darren,

As already mentioned, these jets will work best in the 15.000 - 20.000 rpm range, more will not produce more thrust, but foam.

Your 3000KV motor on 2S will be in the high end of the spectrum at about 19.000 rpm under load.
Do make sure your motor has sufficient torque; a 'midget' motor with a Ø 28 mm can, only has a tiny rotor, designed for revs, not torque, I'd go for at least a Ø36 mm motor.

Regards, Jan.

[MikeA]

darren how far have you got you were talking about this is october been growing your own trees for the wood?

[darrencuk]

Yeah I no lol I been planing this build for like nearly a year I kept drawing on paper wasn't happy so restarted over and over again but finally stuck to it now :) thanks for info guys hope it does go well

[MikeA]

are you going to post some pics of your build then???? %

[triumphjon]

should be an interesting project , im also part way through building my second water jet propelled dory which is using the same grupner mini jet unit  , my first had the nqd drive unit & stock brushed motor

[darrencuk]

just about to start a build thread

[Flash22]

do a search on google for the nqd jet boats these use a cheap copy of the graupner but there are loads that have been converted to run the graupner jet

hobbyking do a xl cnc jet unit just the pics give you a better idea of how things work and what mods you may need/want

http://www.hobbyking.com/hobbycity/store/__13388__CNC_Precision_Jet_Boat_Drive_X_Large.html

[mike50001]

heres a video clip of my nqd conversion,  virtually a copy of the graupner drive.

http://www.youtube.com/watch?v=T0Ajp2_ng7g&feature=youtu.be

2 cell is nippy, an 3 cell is only any use for totally flat water.

an 4 cell , well does anyone know somewhere to get solid drive couplings from?

[HS93 (RIP)]

dont forget you can get these  http://www.jet-drive.de/index.php?option=com_virtuemart&page=shop.browse&category_id=2&Itemid=17  they are also ballraced and work well Just bought a few

Peter