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Unofficial "NQD" Tear into Jetboat Thread

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Old 09-15-2012, 10:46 AM
  #3001
damfurst
 
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Been working some more on the build for the son of a friend. I had an extra Mystery 3000kv outrunner motor so decided to use that to power it. Soldered connectors on and made a cooling plate out of copper plate and tube. Installed both motor and cooling plate by first drilling out mounting holes on drive. I have found it easier to mount the motor by doing this. Soldered ends on a Hobby King 60a marine esc and velcro'd to inside of hull. Hooked some of the cooling lines to esc and then motor cooling plate. Moved onto servo. Using a traxxas waterproof servo I had from a previous build. Used a piece of cut angled aluminum for the mount and a zip tie to fasten to the servo mount. Mount was shoe goo'd to the bottom of the hull. Should be testing it soon before sending it off.

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Old 09-15-2012, 11:16 PM
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so the Outrunner 4450kv motor will outperform the Leopard 4450kv Motor?
I suppose Outrunner motor do not need any water cooling jacket?

Thanks
Quote:
ORIGINAL: sundogz

Quote:
ORIGINAL: spektrumFlux

I'm getting bit of confused..

assuming using 2S Lipo for below setup,
will the [Turnigy 450/500 H2223 Brushless Outrunner 2900kv] be faster compared to [Leopard 4450kv]?

beside the bigger shaft diamter on the Outrunner motor, can it be mounted onto the existing mounting?


Thanks. :-)
I had to edit my incorrect first response - Thank you Ratrunner for the reminder that we were talking 2S here. The outrunner is 600w which makes it almost 3 times as powerful as the 220w Leopard. [link=http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11177]This motor[/link] would be more suitable for use with 2S. It has the same mounting hole spacing, so only needs a 2.3 to 3.17 coupler to install. Be sure to use a high 'C' rating lipo, as it will draw a lot of amps and will puff cheaper batteries. It would be better to use the 2900kv on 3S IMO, it won't draw nearly as many amps - and since you've already burned up one motor....

Edit: Many people are using [link=http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8594]this inrunner[/link] on 2S and 3S with success. I run it in my Jet Skis on 2s and it does very well.
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Old 09-16-2012, 06:20 AM
  #3003
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Quote:
ORIGINAL: spektrumFlux

so the Outrunner 4450kv motor will outperform the Leopard 4450kv Motor?
I suppose Outrunner motor do not need any water cooling jacket?
That particular outrunner is much more powerful than the 2040 size Leopard. And because it is not pushed that hard, does not build up as much heat. But if you are concerned about heat, you can do what Damfurst did (see previous post) and make a cooled mount (Good job, Danfurst!)

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Old 09-17-2012, 05:00 PM
  #3004
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i am working on a way of making my boat self right after being flipped. after 5 minutes of messing about I stuffed the bow of the boat solid with bubble wrap and a little at either side of the boat on the inside plus some on the top of the roll cage. then put a battery in to make sure it was weighted properly.

test 1 didn't go so well it would just sit upside down in the water. the problem was there was nowhere for the water to enter the boat or for the air to leave.

test 2 i added more bubble wrap to the side of the boat so that it sat off center in the water when it was upside down. this allowed the water to come in the antenna hole i use for drainage and drop that side down low enough in the water to let air and water into the hatch and flood enough that it drops and eventually rolls.
<iframe width="560" height="315" src="http://www.youtube.com/embed/LW5AojEeO1Q" frameborder="0" allowfullscreen="">
http://www.youtube.com/watch?v=LW5AojEeO1Q

so now i know what to do i am going to see if i can refine it:

1.by using some kind of ballast tank rather than flood the hull

2.better floats on top rather than bubble wrap. i was thinking a couple of ping pong balls or something.

keeping all water out this boat is almost impossible so either make sure you are using waterproof components or make a sealed radio box . keep your batteries as low as possible on the bottom of the boat on the hull if possible it will drastically reduce the chances of flipping.
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Old 09-17-2012, 05:49 PM
  #3005
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nice one GeoFrancis

I was thinking of some old film canisters (if they exist anymore LOL)
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Old 09-17-2012, 07:11 PM
  #3006
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Welcome GeoFrancis, I can see that you have given some thought into doing this project of self righting one of these boats. Here are a couple of things I have noticed about a boat that I own an MHZ Gecko. One is the shape much narrower than the jet boat. The other is the motor is actually what does the self righting in the Gecko. Once the boat is turned upside down full throttle is momentarily applied and the motor (brushless) will cause enough torque to roll the boat back over so the prop will engage the water. The jet boat with the jet drive could similarily work except the drive contains the stator which takes all the torque roll out of the motor. I think someone once mentioned using a floodchamber as well on this thread, but I don't think anything came of it. Good luck with your endeavor.
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Old 09-17-2012, 11:48 PM
  #3007
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Hi Guys I'm new here & got too tired after reading 30 pages - so humour me please.
Firstly I really have to compliment you on your technical proficiency. I'm really impressed. REALY IMPORESSED !
One of my early ski boats had a Vicalen (sic maybe ?) jet pump which we replaced with a Doen. The 16ft jet boat was fun but my later boat was a 21ft Mastercraft X Star which used half the fuel, ran at half the RPM, made 1/4 the noise, wore out 1/10th as many engines and went 20% faster. If you're not running a (full sized) boat in puddles then jets don't make much sense. Shallow Kiwi rivers though are the jet boat domain - till the pump sucks up gravel like my Vicalen did & destroys the impeller.
Now, to the point - I've got two HobbyKing motors ;
PRODUCT ID: S2445-3890
and
PRODUCT ID: NTM2836-3000
Which one do I run in one of these modified NQD 757 pumps (- is this the one to use ?) & on how many cells please ?
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Old 09-18-2012, 03:28 AM
  #3008
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i got the idea from i post i found somewhere. someone had an auto bailer in their jet boat and when it flipped the air went out and the water came in. because the bow was stuffed with bubble wrap it sank at the rear and once it was near vertcal it self righted. my plan was to expand on that idea by trying to get it to right while it had much less water in it. so i addes the floatation to the top and side to get it to roll much sooner.
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Old 09-18-2012, 03:57 AM
  #3009
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I'm sure most of you guys know, but I will mention it anyway.
Most RC Racers use a flood chamber for self righting the boat.
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Old 09-18-2012, 05:00 AM
  #3010
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Quote:
ORIGINAL: plasticbaldy
I've got two HobbyKing motors ;
PRODUCT ID: S2445-3890
and
PRODUCT ID: NTM2836-3000
Which one do I run in one of these modified NQD 757 pumps (- is this the one to use ?) & on how many cells please ?
I'd choose the 2836 and run it on 3S, but you might have a time locating a 4mm to 2.3mm coupler. And it might be good to water cool the mount like Damfurst has in previous posts. It is unusual that a 28mm outrunner would have a 4mm shaft! The 2445 would need a water jacket which might be difficult to locate, and the kv range is in-between. Try to stick with around 3000kv for 3S and 4500kv for 2S unless you use a larger motor - in which case the kv won't matter as much.
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Old 09-18-2012, 05:23 AM
  #3011
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Quote:
ORIGINAL: Wheelnut

I'm sure most of you guys know, but I will mention it anyway.
Most RC Racers use a flood chamber for self righting the boat.
yea i have seen something like that before but theres not much space for a flood chanber so i built it like a submarine and just made everything waterproof.
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Old 09-18-2012, 02:10 PM
  #3012
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i have came across a problem with my boat the 2436 motor i have in the boat only has a 2mm shaft not a 2.3mm one so i was getting all sorts of wierd vibration.

has anyone found a good replacement for the stock coupling ?

failing that i do like the look of this motor

http://www.ebay.co.uk/itm/048-KV3800...item2c6816246b

2445 3800kv ! rated at 450w this will fly with that motor.

and just use a basic heatsink to cool it
http://www.ebay.co.uk/itm/133-2x-24m...item2c65204da5

because the motor is so big i doubt it will even get warm.
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Old 09-18-2012, 06:53 PM
  #3013
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is the video your talking about? I'm pretty sure it usesa flood method of some sort.

www.youtube.com/watch

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Old 09-18-2012, 07:56 PM
  #3014
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Here's a video of Tim's Tear Into test run. Came out pretty sweet I think. [link]http://youtu.be/JGRyqDzJCIM[/link]
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Old 09-18-2012, 08:23 PM
  #3015
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Nice work damfurst!

How long was the run time using the 11.1v 1300mah 40c?

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Old 09-19-2012, 12:36 AM
  #3016
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Geofrancis,

I have a couple of these boats running these http://www.giantshark.co.uk/black-ma...-p-403839.html from Giant Shark in the UK - they work very well on 3S and a 20mm cooling jacket fits perfectly.

Cheers,
Mike.
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Old 09-19-2012, 02:51 AM
  #3017
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Quote:
ORIGINAL: SkR8Pn



is the video your talking about? I'm pretty sure it usesa flood method of some sort.

www.youtube.com/watch



i havent seen that video before i just read about it on a forum somewhere but you can see how low in the water it gets before it eventualy rights its self. i wanted to get it to roll before there was as much water in it.


Quote:
ORIGINAL: MikeHRC

Geofrancis,

I have a couple of these boats running these http://www.giantshark.co.uk/black-ma...-p-403839.html from Giant Shark in the UK - they work very well on 3S and a 20mm cooling jacket fits perfectly.

Cheers,
Mike.
hmm i didnt think anywhere in the uk was doing motors as cheap as that. thats a nice motor .

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Old 09-19-2012, 07:01 AM
  #3018
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Quote:
ORIGINAL: SkR8Pn

Nice work damfurst!

How long was the run time using the 11.1v 1300mah 40c?

Thanks SkR8Pn! I only ran the boat about 2- 2 1/2minutes, and the battery took around 370 mah to recharge it. I would guess depending on how hard you are running it would run 5-7 minutes on this battery. The motor was warm and the esc was stone cold after this short run.
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Old 09-19-2012, 01:14 PM
  #3019
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did anyone else use the stock radio box for their radio gear? i have my esc and reciever in it and it really makes it look neat. i just need to get a way to mount the battery. i have just been stuffing some bubblewrap between the deck and the top of the battery up till now.




i ended up ordering this motor to replace the 2435 3600kv with the misfitting shaft

http://www.giantshark.co.uk/black-ma...-p-403212.html

just need to get a jacket for it.

the yellow tape on the roll bar is so me and my friend can tell them apart he has some red tape on his.i know the hatch is so bad i know lol i was trying to use the bluntest knife ever. it would have been neater if i chewed through it. plus there is also a 2 inch crack down the bottom of the hull either from jumping rocks or when i dropped it down a flight of stairs.... nothing superglue didnt fix.

i want to install an autobailer after watching that video of the self righting jetboat with the autobailer Ihave to have one ! i dont want to be chasing the boat down the river. i love that it emptied its self after a few seconds running so i think that will be next.
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Old 09-20-2012, 07:51 AM
  #3020
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Quote:
ORIGINAL: damfurst

Thanks SkR8Pn! I only ran the boat about 2- 2 1/2minutes, and the battery took around 370 mah to recharge it. I would guess depending on how hard you are running it would run 5-7 minutes on this battery. The motor was warm and the esc was stone cold after this short run.
Thats not bad, i may have to try one of those lipo's out in the rebuild.

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Old 09-20-2012, 04:31 PM
  #3021
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Quote:
ORIGINAL: geofrancis

i want to install an autobailer after watching that video of the self righting jetboat with the autobailer Ihave to have one ! i dont want to be chasing the boat down the river. i love that it emptied its self after a few seconds running so i think that will be next.
Watching the autobailer in action on that vid is cool but does it seem slow to you? Or is that the normal time it takes the autobailer to do its thing..

I have no idea on how they work but i'm wondering if you could some how speed the process up...



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Old 09-20-2012, 05:39 PM
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i think it takes so long to drain just because the sheer amount of water needed to get it to roll. thats why i was looking at some floatation up top to get it to right with much less water in it.
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Old 09-21-2012, 06:51 PM
  #3023
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Ok so i'm considering painting my sprint.

I thought id better ask what paint to use as i'm not shy to melt plastics with wrong paint.

Any suggestions?
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Old 09-21-2012, 07:13 PM
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the tamiya PC paints will work fine on the boat. i am unsure of others that would work.

i have decided that i will paint mine, but haven't done so yet....

Jason.
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Old 09-21-2012, 07:27 PM
  #3025
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Quote:
ORIGINAL: Ratrunner

the tamiya PC paints will work fine on the boat. i am unsure of others that would work.

i have decided that i will paint mine, but haven't done so yet....

Jason.
Thanks, i'm unsure of colours but really just wanted to still have a hull left after painting it....

Those cheap as rattle's at supercheap probably would also... i've seen it on lexan and it held shape but knowing my luck id melt stuff.

Thanks again
Ja

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