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The Unofficial all things Jet drive thread

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The Unofficial all things Jet drive thread

Old 10-08-2014, 04:17 AM
  #4976  
89MIB
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haha yer ill be the Ginni pig for that motor. i never new you could get jetski hulls that's a grate idea. What length are they?
Old 10-08-2014, 08:24 AM
  #4977  
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You mean the Wavechopper? Or the kehrer jet boat? Wavechopper is 48cm, the kehrer jet sprint II hull is about 66cm.
Old 12-01-2014, 12:25 PM
  #4978  
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Can you provide a photo of the "twin servo mount" for operation of the reversing buckets?
Old 12-14-2014, 12:01 PM
  #4979  
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Hi guys,

Im a modelbuilding nut with a soft spot for jet-drives like most here, and I have been working on a file for making simple calculations on RC jetdrives in order to determine the power one needs to achieve a certain rpm and therefor jetspeed. With this file you can get an insight in what kind of setup (batteries/e-motor) is most likely to give the result you want from your model jet-drive.
It is easy to use; just fill in the required numbers, and it will show the required power to reach a certain RPM.

Remember this file is a first setup; there are numerous more variables to consider, but it is a handy tool that will give a good estimate as to which setup is most likely to work, and which wont.

You can download the file here:

http://www.powerboat-friends-freisin...English%29.xls


I have tried to assemble some of the calculations that people on the Snikwah forum used to design their own jetdrives.Try it and see what you think; any comments on improvements are welcome.

Cheers,

HJ

Last edited by Haje74; 12-20-2014 at 05:21 PM.
Old 01-01-2015, 06:38 PM
  #4980  
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Hi Folks,
I'm totally new to jet drives for boats. Was looking at getting the standard NQD 757-6024 drive with 390 motor from ebay. Anyone know how much thrust this provides?
From what I've seen so far, replacing the stock 390 motor with a brushless motor greatly improves performance, is this true?
One last question - if I briefly connect a 2200 mAh lipo battery to this setup (no speed controller, just for a quick test), would it burn out the motor by overheating, or would it be ok to run 10-20 seconds?
Thanks!
Old 01-01-2015, 06:50 PM
  #4981  
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Hi speed, a brushless setup makes a massive difference. They're total junk out of the box, a lot of them don't work at all, but they're fantastic fun after modding them. I make lots of parts for modding the Tear Into jet unit and can put a kit together with everything you need to mod the boat including the motor, ESC and all other hardware.

A 2S LiPo won't hurt your stock motor and 3S is ok for short bursts if you just want to see what it's like.

Also, I've set up a new forum which is dedicated to Modding the Tear Into where you can post pics of your build and get all the help and advice you might need.

http://sicrc.freeforums.org/nqd-tear...ods-t3-10.html
Old 01-01-2015, 07:24 PM
  #4982  
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Thanks for the quick reply SicRC! What would you recommend in terms of brushless motors for getting the most out of the NQD jet unit with a 2S or 3S battery unit? Will the motor's shaft fit or is an adapter necessary? Any other parts needed besides the ESC? How much would all this run?
Thanks!
Old 01-01-2015, 07:53 PM
  #4983  
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Below is a link to the motor I recommend. On 2S it's pretty quick and on 3S it's crazy Have a look around my eBay store for other stuff I do, the ESC I recommend for that motor is the 35amp one, they're both water cooled.

http://sicrc.freeforums.org/nqd-tear...ods-t3-10.html

I recommend modifying the jet unit too. I run a flex shaft and a 3 blade impeller that I make. There's also a modified stator housing and nozzle (the bits that attach to the back of the boat). My modified stator housing has 2 nipples on it, one provides pressurised water for the cooling system and the other one provides a vacuum, you attach a piece of silicone tube to that and run it through the transom to the bottom of the boat and it sucks out any water that gets in while you're running.

For $129, I do a complete kit with Motor, ESC, servo and mount, all the mods for the jet unit, battery tray, and everything else including screws and cooling system tubing.

I don't do complete kits through eBay though, they take too much commission I'll PM you my email address and we can sort it out, I can send you a PayPal invoice for payment.
Old 01-01-2015, 07:59 PM
  #4984  
SicRC
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I just sent a PM, not sure if it worked though, my email is [email protected]
Old 01-03-2015, 02:46 PM
  #4985  
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Hey Steve,
Thanks for the offer, but I'm not sure I'm ready to make a purchase. Still doing some research. How important is the water cooling if I plan to run in short bursts? Why is a flex shaft needed, is that to accomodate the modified impeller?
Thanks,
Brian
Old 01-03-2015, 03:05 PM
  #4986  
SicRC
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No problem Brian,

Depends on what you mean by short bursts, and a lot of other factors like motor size and kv rating, and whether you're running 2S or 3S. Also whether you're running fast on open water on just messing about at low speed in creeks and rapids.

The cheapest way to go is to use an outrunner which is air cooled, and an oversized ESC, if it's only delivering half it's max amps then you should get away without water cooling.
Old 01-06-2015, 04:54 PM
  #4987  
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Thanks Steve,
Can the 2.3 mm coupler for the NQD unit be manually drilled to 3.17 mm (I assume a 1/8 inch drillbit would be close enough) or does this have to be done using a drill press?

Does anyone waterproof their motors for jet boats (in particular for salt water)?

Would a decent size motor like this one destroy the 16 mm NQD jet unit, or would it be able to handle that power with say a 2S lipo?
http://www.hobbyking.com/hobbyking/s...ner_Motor.html

Brian
Old 01-06-2015, 08:54 PM
  #4988  
SicRC
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Ideally you'd use a lathe to drill the coupler out, but even then it may not run true, but you've got nothing to lose by trying.

That motor will be fine Brian, and no need to waterproof it, just give your motor a squirt with a water dispersant spray before and after running. Inox is the best spray I know of as it doesn't leave a residue build up the way WD40 does. Another brilliant product is CorrosionX.
Old 01-08-2015, 04:50 PM
  #4989  
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Hi Steve,
Another thought I had was getting two NQD units and using this smaller motor that shouldn't require a modification to the shaft coupler:

http://www.hobbyking.com/hobbyking/s...erCooled_.html

Do you think a single 2S lipo would be enough for two of these if I just want to do ~10 second full out bursts and don't care about running for long durations? I am leary of using a 3S lipo because these are 4800 kv motors so they should be turning over 50,000 rpm on a 3S which is way too high for an NQD unit, right?

Do I even need an ESC if I am just doing short, full out bursts?

Do you think this 2 motor idea is more powerful or is it better to choose a single bigger motor on one NQD unit. It looks like this is the best watercooled choice they have instock:

http://www.hobbyking.com/hobbyking/s...erCooled_.html

Does the shaft collar on the NQD unit actually block water from going into the motor, or is it relying on the motor being above the waterline?

Thanks!
Brian
Old 01-08-2015, 10:42 PM
  #4990  
SicRC
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Whether you can run 2 jet units depends on the hull. it would need to be quite a bit bigger than the NQD Tear Into and have quite a shallow V, otherwise the jets will suck air as soon as you start to plane. Can you put up a pic of the transom and some measurements?

If you want to use a brushless motor then you have to use an ESC.

Those little motors would be a good choice for a twin setup if the hull is suitable. ON 2S those motors are great, but on 3S you'll cook the front bearings.

The rubber shaft seal does keep most of the water out, but keeping the shaft greased is a good idea too.
Old 03-02-2015, 02:53 AM
  #4991  
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Default My jet boat collection.

Thought I might share our collection of jet boats. As per most it started with the mini jet boat, then I spent some time hunting down one of the ABC Hobby jetski's (have a second one nib) and last the kmb jet sprint boat.
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Old 04-07-2015, 09:31 AM
  #4992  
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Hi guys I posted a new project in the electric forum (it's a jetdrive project so just wanted to let you know);

http://www.rcuniverse.com/forum/spee...-jetdrive.html

Let me know what you think; my guess is I could go for bigger batteries

Cheers HJ

Last edited by Haje74; 04-07-2015 at 09:45 AM.
Old 05-10-2015, 05:31 AM
  #4993  
wildwillhappy
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hi all
just found this site, come over from rc groups. Cannot find any nqd jet boats in uk but did look at a site to import them from china but then what would I do with a whole load of them, we all know that the rc gear is not very good and the speed controller and batter are pants so would have lots of hulls and jet drives left over.
wild
Old 07-02-2015, 07:35 PM
  #4994  
Quicksilver
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Hey you guysss!!! I'm back and planning on the jet villian v.10 to be RTR by tomorrow! It will be brushless, 12 cell and weigh roughly a 1/3 of v.7.
pics to follow soon
Old 07-03-2015, 02:29 AM
  #4995  
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okay, it's done, so the hull is modded a lot more now, I moved the drive back 3 inches and added the step in the transom. The the entire electronics outfit is replaced, with the entire setup my truck, the Traxxas E-Revo VXL. I'm very excited to get this in the water.

some old and new photos.
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Old 07-14-2015, 11:11 AM
  #4996  
Quicksilver
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So some of you might have guessed, this didnt work out. I blew a cell in the batteries. I was running 12 cell. The motor and esc were running cool but the batteries cannot handle the amperage. Back to the drawing board. In the mean time, I'm putting that running gear in a 10" RIB lmao, it'll be a monster, will have a much smaller prop.
Old 10-09-2015, 07:43 PM
  #4997  
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http://youtu.be/IVoJMZdntcA New jet boat from Youngsters jet boats 23" Brinksman Feral. Maiden voyage on the pond.
Old 10-22-2015, 09:36 AM
  #4998  
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http://youtu.be/adQtE1jR5N4 Here's new video by Youngster himself of the Brinksman Feral.
Old 11-07-2016, 05:52 PM
  #4999  
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Sale going on the Mickiebeez jets , price will not be repeated:
http://www.ebay.com.au/itm/Mickiebee...-/112179066310?
Old 01-23-2017, 04:31 AM
  #5000  
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Its Been about 2 and a half years since I posted up. I had this on the back burner for a while but its almost done. Its had it test run and about to get some paint. its extremely fast off the line.


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