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Unofficial "NQD" Tear into Jetboat Thread

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Old 08-22-2011, 11:53 AM
  #2226
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wow, that's impressive
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Old 08-24-2011, 04:28 PM
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Quote:
ORIGINAL: QIK-RX4

Get em while the last guys!!!!

http://cgi.ebay.com.au/ws/eBayISAPI....84.m1439.l2649
Are they a direct fit for the NQD Jet boat? Does it fit the stock shaft from the boat etc? Diameter etc?

Thx
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Old 08-24-2011, 11:39 PM
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yes , props are perfect fit on stock shaft, i just received 4 from this seller
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Old 08-25-2011, 12:02 AM
  #2229
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sorry to come into this thread late (90 pages late but after reading the first 20 pages skipped to the last one lol) but quite a while ago i purchased a modded nqd jet boat (poorly modded i might add) which had a fried esc, ok, so replaced that and ran it a few of times on 7.2v nmh batteries, was so so, and lost interest and it all sat in the cupboard for a couple of years. Now the bug has reared its ugly head and bitten again so back to r/c playthings .  ok, so i got some 11.1v lipo's, phaffed around a bit and had a play, problem is my speed is pathetic
so rather than trawl throught the last 70 pages am hoping somone with wisdom and knowledge will tell me what i need to do! once i get this right i plan on getting 2 more boats and modding them properly so my son and i can have some fun!
here is what i have:

turnigy b2445 2900kv motor (water cooled)
11.1v 3S 5200mah 20c batteries (too heavy???) http://www.ebay.com.au/itm/ws/eBayIS...m=180679326155
35A esc (water cooled)

pretty sure i have major conflicts there? but after many hours of googling and finding different opinions felt this was the best way to get expert help

i dont have an esc programming card and im not really sure if that will help me? the esc was a no name ebay purchase.

all i know is my brushless vxl rustler goes like the power of p*** on these batteries and my boat doesnt seem to me to be much faster than a stock item?? and all i want to do is make it SCREAM!!!!!!!!!!!

thanks in advance for your wisdom
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Old 08-25-2011, 05:14 AM
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I'm still pretty new to the scene myself... but a 5200mah battery is WAY too big. I have these:
[link]http://www.hobbyking.com/hobbycity/store/__10279__Turnigy_2200mAh_3S_40C_Lipo_Pack.html[/link]
[link]http://www.hobbyking.com/hobbycity/store/__16346__ZIPPY_Flightmax_2200mAh_3S1P_20C_USA_Ware house_.html[/link]

Don't weigh a ton... and I have a good 10-15 minute run time for sure. Keep in mind that higher mah only increases your run time, not power.

Next I'd get a higher kv motor.... the higher the kv, the faster the rpm. I run this motor and it flies!
[link]http://www.hobbypartz.com/07e-c-sl-10t-2848-blue.html[/link]
and this esc
[link]http://www.hobbypartz.com/07e-c-seaking-60a.html[/link]

I'd say you have a combo of things wrong... and the mystery ESC may be part of it. Less weight, higher kv motor and a good high amp esc and you should be flying across the water.
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Old 08-25-2011, 05:41 AM
  #2231
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Swervyn: the kv rating of the motor you're using should be perfect for that jet drive, but the battery is heavy and too low a C rating. Go with a 3S half that size, with a 40C rating and it should do quite nicely.

TheOtheSide: If you are using 3S lipos with that 3900kv motor, then I'll bet the speed is topping off well before the rpm's (noise). That motor should be used with a 2S lipo to stay within the usable range of the jet pump. Do you have a video of your boat in action?
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Old 08-25-2011, 05:51 AM
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Quote:
ORIGINAL: sundogz

Swervyn: the kv rating of the motor you're using should be perfect for that jet drive, but the battery is heavy and too low a C rating. Go with a 3S half that size, with a 40C rating and it should do quite nicely.

TheOtheSide: If you are using 3S lipos with that 3900kv motor, then I'll bet the speed is topping off well before the rpm's (noise). That motor should be used with a 2S lipo to stay within the usable range of the jet pump. Do you have a video of your boat in action?
No clear video... just on choppy water. I'll try a 2s next time I'm out and see what it does.
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Old 08-25-2011, 10:16 AM
  #2233
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Sundogz knows his stuff... he modded my boat and it runs great!
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Old 08-25-2011, 03:25 PM
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Thanks heaps guys, I think I may be getting my head around it all.

Just to confirm:

1. A higher kv motor produces more rpm but less torque, but the jet unit can only handle so much rpm before it starts to cavitate, not being able to draw up enough water through the inlet to provide enough water for the speed of the impeller?

2. A higher Mah battery provides longer run time (more petrol in the tank, theoretically 4800mah providing around double the run time of a 2200mah battery), but also is close to double the weight, but the c rating of the battery is what provides the power: higher c =more speed, up to the max load of the motor

3. If a motor is rated at 34A max load then the c rating of the battery ideally should close to match that (35C), so by using a 20C battery in my 34A max load motor I am not providing enough power to the motor to get the full rpm's. (is this is why I have slow speed issues but get decent run times from my 5200Mah battery?)

4. The esc size should theoretically be based around what?? the battery c rating?

A 3s battery running a 2900kv motor will give roughly 32000rpm (but wont the motor spin at 29000rpm max??)
A 2s battery running a 4500kv motor will give roughly 33000rpm, similar top speed but less torque

Any higher rpm and the jet unit simply cant draw enough water to operate (and would more than likely disintegrate anyway)

This is why (thanks SpeedDaemon) 3000kv motor and 3s battery is recommended max combination (33300rpm, but wont it spin at 30000max rpm??) as any more rpm the jet wont handle?

Thanks in advance again, and sorry if you feel you are repeating yourselves over and over!! cheers





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Old 08-25-2011, 06:39 PM
  #2235
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Hey there Swervyn,

You're pretty close on most things.

1. A higher kv motor will produce more rpm per volt supplied to it. for example a 1kv motor on 1s, 2s, and 3s, will produce 3.7rpm, 7.4rpm and 11.1rpm respectively (ignoring running losses). The maximum rpm comes down to the quality of your motor, and the maximum switching rate of your ESC. Essentially a low kv motor should be able to turn as fast a high kv given enough power.

2. mAh is typically read as the 'storage' capacity of the battery, but also directly relates to maximum output current.
Basically you're right saying a high mAh battery will run longer, but asC is used to quantify the maximum working current the battery can produce based on the mAh, you need to look at both values to work out the current (A) the battery will produce. More simply a 1000mAh battery stores enough energy to produce 1A for 1 hour. But we want 30A+. So C x Ah, gives the max current. For example the above battery at 1C, will give 1A, and at 10C - 10A, 20C - 20etc...

2b. IMO the C rating is more important than the mAh (within reason). I think (this is opinion only) that if you're choosing between two similar batteries, go for the lower mAh, higher C battery ie (3000mAh 20C > 4000mAh 10C)

3. I think this is answered in 2 ^. A = Ah x C. (Ah = mAh/1000) Your 20C 5200mAh should be providing 100A+

4. ESC power should be at least equal to the max power you're running, but I suggest buying the strongest ESC you can afford (again within reason - some crazy 200A beast is overkill). If your setup is going to run 34A, then a 35A ESC will be running at 97% at WOT, so it'll get hot. A 50A ESC comparitively will only run at around 70%, so will never struggle.

Again IMO, I think 3000kv 3s is reccomended a lot, not because it works out well on paper. But rather because it works out well on the water. I would find a 3000/3s or similar combo, then plan your batteries and ESC around that.


Hope that helps...
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Old 08-25-2011, 08:20 PM
  #2236
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Thanks for the kind words, Jeff. Glad to hear all is well.

Swervyn, I hope Similar cleared that all up for you! The higher C rating can dump more amps when called for. I believe that is your biggest problem, 20C is holding it back. Get the highest 'C' rating that you can afford. When you fry the 35A esc, consider a 60A or larger so it won't have to work so hard. The hardest thing on an esc is puttering around. I know that doesn't sound right, but at WOT it just passes the current on through. When going slow, it adjusts the current by pulse width modulation, and the FET's and caps get the brunt of the load (oversimplifying here). As inexpensive as they are nowadays, a 100A Chinese esc would be cheap insurance and not take up much more room.
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Old 08-25-2011, 10:30 PM
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Great explanation Similar and thanks also sundogz, thank heaps,much appreciated

ok, so am going to get a couple of these batteries : http://www.ebay.com.au/itm/2200mAh-1...item2a124275e7

and run them with my 35A esc and 2900kv motor http://www.hobbyking.com/hobbyking/s...idProduct=4197

and if I fry the esc, so be it! I like eliminating problems by blowing them up   am basically after a setup that performs well and is reliable enough to know something is not going to fail everytime I put it on the water!\ Once I get it sorted will get 2 new boats and put the same specs in them so the boy and I can have fun (or maybe make mine a little bit faster )

Once again thanks and I will now slink back into the corner and let somebody else ask all the same questions over and over lol

Cheers
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Old 08-26-2011, 04:52 AM
  #2238
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If I had any reservations about that motor, it would be the shaft size. It could be vulnerable to bending. The NQD jet shaft is 2.3mm. Did you find another coupler to fit, or did you use the original (which could cause wobble)? And are you water-cooling the motor (which might be necessary after going to the 45C lipos)?
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Old 08-26-2011, 06:06 PM
  #2239
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Had the original coupling on the motor and yes, there was wobble, I eliminated most of it by making an aluminium mount for the front of the motor so it wasnt just supported by the jet housing. Motor is water cooled via aluminium tubing that cools the esc as well. But I see your point so I might search for another motor with jacket that has the same size shaft, 1 less thing to fail! Thanks for your advice
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Old 08-30-2011, 07:35 PM
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More Suitable MOTOR for the NQD TEAR INTO ?

Leopard now makes a [link=http://www.ebay.com/itm/Brushless-Motor-2040-13T-KV4450-2-Poles-LEOPARD-IM012-/260799364101?pt=Radio_Control_Parts_Accessories&hash=item3cb8da7c05]4450kv 2040 (13T)[/link] motor that should be more suitable than the 4800kv motors everyone has been using lately (2S lipo). This works out to about 2966kv on 3S which is the ideal range for the NQD pump. This should eliminate the 'runout' where after about 3/4 throttle it just makes more noise, not more speed. If you have run this motor, please post results.
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Old 09-06-2011, 07:33 PM
  #2241
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4 pole vs 2 pole??

and why are the 4 pole motors 3 times the price??

just wondering lol
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Old 09-06-2011, 08:33 PM
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4 pole have more torque. They have a more complex winding pattern than the 2 pole motors, hence the increase in price... I'm sure marketing also has something to do with it
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Old 09-06-2011, 09:02 PM
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ahhh, leopard water cool jackets only fit their 4 pole motors too i think
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Old 09-06-2011, 09:19 PM
  #2244
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I believe you are right. I don't see any Leopard 20mm jackets available. You'll have to get another brand jacket. Ain't that a shame?!
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Old 09-06-2011, 11:21 PM
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well i just had a silly ebay and hobbyking frenzy lol

4 batteries
2 motors
2 cooling jackets
1 lipo sack and some silicone tubing
thermometer gun
camber guide (for vxl rustler)


might be a while before i can tell u how the motor performs sundogz but I liked the idea of the same sized shaft so went with them, got some 2s 2200mah 45c and 2s 4800mah 45c coming, arrggghhhhh just checked email and 2200 are 3s lol, hope they are nice and let me change to 2s dammit.

also found a jacket that looks like it will fit ok :http://cgi.ebay.com.au/ws/eBayISAPI....m=260630244153

just as well i got rid of the wife as I wont have to conceal the packages when they arrive! And anyway, this is a far less expensive pastime than marriage!
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Old 09-07-2011, 03:45 AM
  #2246
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G'day Peoples,
I've been reading this forum for a while now (up to about 30pages or so), i know i should (and will) read the whole thing and i'll get the answers i'm looking for but just to fast track a little, i've got mine all stripped out about halfway through tweaking the pump but still haven't ordered any running gear as i dont know what i need?
So appolagies in advance for asking this (just want to get it back together) but what motor, esc and batts is recomended?
Cheers Nigel
Oh and for the cooling jacket to suit the 2040 try
http://shop.rcboatbitz.com.au/index....6e0bdc8bae97e9
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Old 09-07-2011, 05:53 AM
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Quote:
ORIGINAL: swervyn
also found a jacket that looks like it will fit ok :http://cgi.ebay.com.au/ws/eBayISAPI....m=260630244153

just as well i got rid of the wife as I wont have to conceal the packages when they arrive! And anyway, this is a far less expensive pastime than marriage!
Yes that jacket will do just fine, and the price is right. Now as for getting rid of the wife, that sounds a little extreme. But you have a point about the expense!

Dreadrock: Most of your answers can be found in the last four or five posts. If you want to run 2S lipos (lighter), I'd suggest going with the Leopard 4450kv 2040 with a water jacket. If you have 3S lipos then you'll want a motor in the 3000kv range with a 2.3mm shaft so you can use the original coupler. In lipos, 2200mah is a good balance of weight and runtime, just be sure to get the highest 'C' rating you can afford. Turnigy Nanotechs stand out here. As far as speed controls, I've always preferred the Seaking/Turnigy 35A esc as they are (usually) reliable and easy to program. I say usually because I just experienced bec failure in a new unit a client supplied and will need to install an external bec to make all well again. If not Seaking, then go with something in the 50-60A range if you want it to last.
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Old 09-08-2011, 05:21 AM
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Hi, new member here - Ihave been lurking for a while and have read through this entire thread. I have to thank everyone who has contributed so far, Ilove this thing! Istumbled into the NQDthread by accident one morning and after that Ihad to have one

Based on the info posted so far the boat is running the following:

2800kV 2838 Inrunner with water jacket
Turnigy 35A Marine ESC
Turnigy 2200mah 3S 25C Lipo
Spektrum MR3000 reciever
Bog standard Futaba servo.

Ihave cleaned up the intake so that it is smoothed out, and have the impeller set as far back as poss so that the thing sits snugly in the exhaust portion- the water has no choice but to go out the back!

Water cooling pickup is from a pop-rivet head that has been epoxied into the stator housing, exits via another pop rivet through the hull.

The entire nose is stuffed with polystyrene so that it shoudl never be able to sink. Ever. The jet drive was removed , the hull cleaned and then sealed back in with bathroom sealant. So far no leaks. Imade a lid from styrene to go under the two guys and keep things more watertight. It squishes down onto foam draught exlcluder strips and seals the boat, well 95%of the time it does.

My problem is that it constantly loses prime if the water is not like glass. Pics and video below- I am thinking of fitting a less restrictive grille, but need to get my hands on something suitable. When the water is flat the performance is great! Ihave tried moving the battery forward etc but still not much change. Does the group have any other suggestions?

Any ideas people may have on things to try?

Anyways, here are the bits you want to see!

Losing Prime
http://s166.photobucket.com/albums/u...t=MOV05605.mp4

Not losing Prime
http://s166.photobucket.com/albums/u...MOV05040-1.mp4





















Any suggestions on the priming thing are appreciated- once I get that sorted I can try some moving water

Thanks



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Old 09-08-2011, 05:44 AM
  #2249
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Yes, your intake guard is too restrictive - try expanded metal or screen with a more open pattern. You can find 'file holders' made of this material in the office section of department stores. This is what I've been using lately - held on with hot glue.
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Old 09-10-2011, 05:33 AM
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Quote:
ORIGINAL: sundogz

Quote:
ORIGINAL: swervyn
also found a jacket that looks like it will fit ok :http://cgi.ebay.com.au/ws/eBayISAPI....m=260630244153

just as well i got rid of the wife as I wont have to conceal the packages when they arrive! And anyway, this is a far less expensive pastime than marriage!
Yes that jacket will do just fine, and the price is right. Now as for getting rid of the wife, that sounds a little extreme. But you have a point about the expense!

Dreadrock: Most of your answers can be found in the last four or five posts. If you want to run 2S lipos (lighter), I'd suggest going with the Leopard 4450kv 2040 with a water jacket. If you have 3S lipos then you'll want a motor in the 3000kv range with a 2.3mm shaft so you can use the original coupler. In lipos, 2200mah is a good balance of weight and runtime, just be sure to get the highest 'C' rating you can afford. Turnigy Nanotechs stand out here. As far as speed controls, I've always preferred the Seaking/Turnigy 35A esc as they are (usually) reliable and easy to program. I say usually because I just experienced bec failure in a new unit a client supplied and will need to install an external bec to make all well again. If not Seaking, then go with something in the 50-60A range if you want it to last.
Thanks Sundogz, and everyone else that has posted in here (still going(damn this a long thread)) i've ordered pretty much everything need to get this puppy up and running (i think so at anyrate), so now it's the waiting game for everything to show up. I'm sure there'll be stuff i've missed (first electric an all) but hey. Got bored and started on the paint scheme today, kind of out there really, i must have been in a crazy frame of mind...lol
Hope to get some pix etc together shortly to share
Cheers Nigel

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