Unofficial "NQD" Tear into Jetboat Thread
 

75 pages of jetdrive stuff, so i decided to start this for the guys modding the "nqd tear into" boats

My Setup :

Tear into boat
3500kv 400 size outrunner
3s 2200mah lipo
Hyperion Titan 30a esc
GWS micro 6ch receiver
Digital micro servo for steering.
Custom brass coupler
Modded jet pump : have sleeved the bearing surface where the shaft runs through the jet unit with 1/8 k&s brass tube, sharpened the stator fins.

First run stock was quite pathetic, stock electrics are junk.
2nd run with the above mods - quite quick until an un harmonious vibration arose. On further investigation it turned out to be the impellor sliding back on the shaft, so i drilled a 2.5mm hole and tapped a 3mm thread and put the 3mm set screw through onto a flat i filed on the shaft
3rd run - Just nuts, this wee thing does 45/50kmh now, excellent handling and acceleration.

All in all im well impressed.

Next mod will be to go to a lower KV motor and/or try the 3500kv Motor on 2s lipo.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

It's Matt right??
Do you have any pics of this boat.
I do love the Kiwi way of hacking up stuff to go faster. Mr Hamilton did it once, and that was it. !!
Then there was John Britten, Tom Walkinshaw, and a few other famous Kiwis who knew how to get the goods out of a budget build.

Keep us (me) posted.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

Hey Simon

Yep some pics, i will take it for a run shortly and video it had it in my mates pool yesterday, since the brushless/lipo repower its way too crazy for the pool though... haha

RE: Unofficial "NQD" Tear into Jetboat Thread
 

Matt, that looks like a neat little boat and would do me nicely as a pond basher, where did you get it.
I hope it was locally "so it has low carbon miles":D
No really I hope it was locally so I can get one easily too.
Keep us posted and as you know vids are always welcome even though I can not do them yet.
Cheers.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

here you go man ill give you a boost on this one . you can get them on ebay heres a link to one http://cgi.ebay.com/New-Radio-Contro...d=p3286.c0.m14

look around you can find them for diffrent $ some even have name your lowest bid . theres even one that some one has already cut open for $55 .

RE: Unofficial "NQD" Tear into Jetboat Thread
 

Ah Simon, i will put you in contact with the guy i got it from off tardme. much easier and cheaper than getting through e-bay. i will PM you his details.. at 80$ nz its a good buy.

for around 100$ usd you can get a BL/lipo/esc and Charger

RE: Unofficial "NQD" Tear into Jetboat Thread
 

The intake for the pump has this drop down plastic block that can be totally removed from the unit giving access to impeller and shaft without removing the jet, this hangs down as a water trap a little, but inside it also has a square step that cannot possibly be good for flow into the jet, it is only 3mm wide but none the less a step where water entering the unit will be hitting creating drag and thus rubbing me of speed.

Will take a vid of the little beastie after work tomorrow

for some reason shipping from US to NZ is crazy prices, but shipping from say china is way cheaper.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

Hey Crab, I too have a NQD jet boat that I have started modding. I took everything out and replaced the jet drive with Graupners mini drive. That let me run a 550 motor that I had on 8.4v. I know that my setup is quite heavy but speed is not my main objective at this point. Any way I'm glad to see a thread just for this boat and will check back from time to time. damfurst

RE: Unofficial "NQD" Tear into Jetboat Thread
 

Hey dam, the drive ya replaced is pretty much an exact duplicate of the mini graupner, only improved upon in terms of minor differences... although I can't remember the graupner is sleeved... I don't remember seeing one on the unit(I think they're larger units are sleeved). Anyways it's just as easy to throw in a piece of brass on the knock off drive.

Ivan.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

the nockoff is 1mm bigger and both doesnt have bushings . but you can run a bearing on the grupner . i have the part# in the jet thread posted twice . and the motor mount is better on the nockoff even though it is a 28mm mount . the grupner is weak and will brake in half . but that doesnt make it trash you can cut the mount off and use a alum angel mount .

RE: Unofficial "NQD" Tear into Jetboat Thread
 

Going to put the GPS in the jetboat tonight and get a speed reading, for me its all about speed since im an Avid racer :P

RE: Unofficial "NQD" Tear into Jetboat Thread
 

hope it's the geko... too much weight with real gps, I had run a boat beside knock off, approximately 20-25kph, more speed available without grate.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

yeah the etrex unfortunately my gecko went bye bye into the drink, was taped on top of my rigger doing 55mph, it decided to come off... DOH the etrex is a little heavier but oh well.

Yeah the grate was the first thing i removed, going to flow the intake a bit and see if i can get a bit more out of it.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

Not sure if ya read it but dragon and a couple guys made custom smaller exhaust jets to get increased acceleration and cornering. not sure if it helped top end. The drives do max out, I've maxed mine on 11.1v with 3200rpm with grate.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

well it did 43kmh on GPS, not bad really. Managed to borrow a ghecko off my mate and put it inside the boat instead of taping the E-trex to the top

Couldnt do a video as it was raining didnt want to get my phone wet

This weekend I will flow the intake out - More in - More out..

I think sharpening the inside of the stator fins and cleaning up all the burrs on the impeller was a bit of an improvement

How do you know its maxxed out ? Have you guys done any testing as in Litres per min to quantify the changes the mod is making?

RE: Unofficial "NQD" Tear into Jetboat Thread
 

Keep putting more power to it, no change is *****g it out. Nice numbers, was wondering what it pulled without grate. Big difference.

Ivan.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

headhunter right there is a max . theres a point where you can only flow so mutch water throw the impeller . when that happens it backs up . you can also over power and make it slower by actally splitting the oxasgn and couseing the drive to airrate

RE: Unofficial "NQD" Tear into Jetboat Thread
 

ok, I'm gonna try here, The maximum output velocity of jet drives are directly related to intake gullet rake and volume, as well as intake area. Then the other variables, impeller efficiency, pitch, venturi shape, size and output area. On top of the drives capabilities, boat design is key, dead rise, how wet the hull runs...on and on.

The key principle and this is tough to wrap ones brain around is this, a boat or aircraft can only go faster if the output velocity is greater than the intake velocity. So simple... nope this means if the jet cannot accelerate the water faster than it comes in than you go no faster. With an impeller with a certain pitch, you can only accelerate water so fast. Since this is not a surface drive where the boat is riding on a blade, you put that prop in a tube and speed it up, eventually bubble will form on the leading edges of the impeller and your efficiency will decrease. These bubbles stay in the duct unlike a regular prop, so the jet stream aerates due from the impeller cavitating. Further more the only way around this, is complicated. Almost bordering on bioengineering. The intake and outlet of the venturi must be variable or the impeller must be variable pitch.

I'll leave it at that for tonight, but it's still not this simple at all. I've written this out so many times and it doesnt get any easier. This one is pretty good, at least to me. Try searching around, not much info out there on the theory behind water jets or should I say beyond the simplified theory.

food for thought.
http://en.wikipedia.org/wiki/Jetboat
here's a big one, but I recommend anyone interested in jet pumps to read through this whole thread
http://www.boatdesign.net/forums/showthread.php?t=11254


ooooo found something related a neat chart...notice thrust has to go to zero [:-]
So the next thought which you've already started thinking about is how to go faster......that second link goes pretty in depth with that

RE: Unofficial "NQD" Tear into Jetboat Thread
 

By flowing the intake i mean smoothing out the casting lumps and the big square edge thats on the back wall of the intake. Im also thinking of experimenting with vortex generators on the intake..

Thanks for the post quicksilver, Interesting about the variable pitch impeller, my guess is it would be exp to manufacture and maintain on the model jet unit though.

id like more info on Bioengineering in the jet unit?

RE: Unofficial "NQD" Tear into Jetboat Thread
 

I've got to find all the sites, but it's basically a concept that you can change the intake size and shape using flexible materials. Which on a large boat is no easy task...a lot of its theory and some of it is in the design phase. I say bioengineering, since theyre trying to use these materials in a way like no other. The material would have to be controllable.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

to give some of my thoughts on increaseing speed . i tryed to do it with smaller nozzles . but really it doesnt work that way b/c the flow just backs up and comes out the sides . to increase water speed it needs to be done in the stater area then dricted throw a smaller nozzle

RE: Unofficial "NQD" Tear into Jetboat Thread
 

correct! this is why I'm thinking of building one. The hardest part imo of building a jet unit is the venturi aka bowl, that holds the stator. I'd love to use aluminum, but since brass is so easy to work with, I'll probably use that.

The whole idea is that at higher speeds the intake should be smaller, and the output should be smaller, problem is, you're increasing pressure, so at lower speeds, you'll be less efficient, since you wont be ramming water in like at high speeds. This is where the variable intake comes in.

I've got a question could I use two radios in the same boat on different frequencies. I dont know if they still interfere due to proximity. This way I could experiment with a variable intake and output. I want to make a square boawl and nozzle so making is variable is easier. Would kind of be a test mule.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

If your testing jets, make a little dounut shaped tub, mount jet against cheap weight measuring stuff, fill tub run jet measure. Would be easiest way to screw around and test. But if you really want the 2 radios in boat, yea u can do it, would probably be better if one was on 75 and the other on some other, but I guess it also depends on radio. I got rid of my other radio went with airplane(spektrum 2.4 dsm2) radio so no glitching etc, can stick 2 receievers on same boat no problems.

Ivan.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

ah I see, I thought by bioengineering that you were referring to atomizing the water changing its molecular structure in the jet or something lol.

I have a few things i want to test on this little unit :

Litres per min to measure volume. - was thinking of making a tray to feed 10l of water into the jet and measuring the time taken to pump the water.

And force - Headhunter - exactly what i was thinking using the wife's kitchen scales :)

once I have a baseline for both, I can do some mods and quantify them. - they may be worse, may be better, least though you can measure and compare

on *****g the jet out - feeding it more power may have increased RPM , but likely reduced torque.. would be interesting to test a few diff KV motors with the above tests.



on the two radios, as long as they frequencies are separated by .100mhz it should be fine. that said I would use a toroid (choke) on the esc lead from the RX.

I have a 6ch radio from my heli that could be used to control an adjustable screen to cover some of the intake. im not going to wast time on this little boat doing that, but might order a big ass graupner #5 unit and build a jetsprint boat to suit.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

i did this two would like to know what you come up with . but i got a max throust of 16.86 oz

RE: Unofficial "NQD" Tear into Jetboat Thread
 

Thanks for the input head and dragon. The other reason I replaced with the graupner is I wanted to build a mini jet v like dragon and thought that the nqd one would fit better with it already set up for a 380-400 size motor. Since my last message I went to a 9.6v a123 battery and wow what a difference. I know from all the other threads that you guys run more 2s-3s lipos, but I think I'll stick to this set up as it works well for me. Need to fine tune some of it though. Anyway keep jetting>

dam

RE: Unofficial "NQD" Tear into Jetboat Thread
 

yeah that drive is a little lighter then the grupner drive and you wont have to make an adapter . like i said once before i would love to see a nother mini-jet-v :D

RE: Unofficial "NQD" Tear into Jetboat Thread
 

Hi all, Just wondering if cavitation is as much a problem for you all or not. It seems like if I turn just right or hit waves at the right angle there goes the prime and all control. I do have the bars on the graupner jet I have in my nqd and wondered if removing them would solve part of this problem. My set up is quite heavy but losing prime still happens. I also wondered if building some kind of water ram for the intake would be an option and if any of you have tried that. Thanks, Dam

RE: Unofficial "NQD" Tear into Jetboat Thread
 

Dam you have a pick of your intake? Maybe some pics inside too? What kind of water are you running?

RE: Unofficial "NQD" Tear into Jetboat Thread
 

i think after reading this and watching the youtube vids i am going to buy one of these. a couple of questions: what kv motor should i get? i have a quark 33, spektrum M8 radio and reciever, 11.1 lipo. i want it to be a fast rapid runner in the creeks around my place. second question what servo is recomended and will i have to make a servo mount. i can make the mount is weight an issue with the material or can i cut some alluminum and go?

lovin this smaller jet thread that other thread is out of control.

thanks guys this will be my first boat build, i am an 18th scale offroad buy and crawler.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

You can use any servo you want, my buddy swears by the big heavy servo, me I go with a small light 5gram servo. For mount, just get a small piece of aluminum angle, notch out where servo sits.

http://www.rcuniverse.com/forum/m_65...tm.htm#7031632 for ultra light servo mount
http://www.rcuniverse.com/forum/m_65...2Cmount/tm.htm for heavier duty servo mount.

Have had really really good luck with this motor(3 boats), others have tried 3200-3600rpm/kv shoot for 30-40amps
http://www.unitedhobbies.com/UNITEDH...idProduct=4200
combo'd with this esc
http://www.unitedhobbies.com/UNITEDH...idProduct=6318
but requires programmer card
http://www.unitedhobbies.com/UNITEDH...idProduct=5448

haven't had luck on the turnigy esc though... although my motor could just be bad.

Ummmm... you'll want to sleve the shaft at some point or drill it out larger and add a bearing where the rubber grommet is, as the shaft sits in plastic protected by grease which doesn't last too long. (wasn't designed for high rpm).

With that motor I posted, on 7.4v it pulls 23 amps, on 11.1v it pulls 30 amps. Add cooling lines to the motor and one or two to the esc(merely by gooping in some aluminum tubing against cooling that's already there.

Other tips, when cutting top to get to the electronics out and replace, leave the posts! leave like a half inch around the top so you can add some foam or gasket to keep water out. Also the decorative engine tips need to be pulled off and siliconed or gooped. Ummm... very thin carbon fibre rods make great grills, just notch in the plastic then goop/epoxy. Uh... make sure you get all the glue out, it's heavy. You'll have to mess with cg once done, once you get cg right, boat works really really well and helps prevent loss of prime going up river.

That's about all i can think of... oh batt, you can go 4400mah with this setup perhaps more. Have tried both 11.1v and 7.4v with this amount of juice.

Ivan.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

I just bought one of these things for my christmas present. I took it out stock christmas morning and the performance was lacking but I expected that . I am just happy that it works. I'm going to try a 3200kv motor with a 2s lipo and see if that makes it do what I want. I'm just running little creeks.
MikeV

RE: Unofficial "NQD" Tear into Jetboat Thread
 

I got it running with the bl motor/lipo and it was great. Until I broke the impeller. Anybody know how to get parts? I did contact the seller, am waiting for a response.
Thanks
MikeV

RE: Unofficial "NQD" Tear into Jetboat Thread
 

Quicker and cheaper would be to get prop from hobby store and throw on high speed drill or lathe, then put a file to it till it's the size you need. Take your time. If your doing an octura, make sure you have a good mask, the whateverberilium is highly toxic, will not come out of your system. The second more likely option is to get graupner mini jet prop and shaft replacement, drill out old and sleeve in a brass tubing as you'll need to do it anyways at some point.

Ivan.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

headhunter is right. your not going to get replacement parts nqd doesnt even offer them on there site . i would do the grumpner impeller b/c its the easest to do . or you can get a prop form ose . ill post a link to both .

http://www.cornwallmodelboats.co.uk/...upner_jet.html look at the bottom at the 19mm grupner impeller

http://www.offshoreelectrics.com/pro...od=grp-2318.26 this is the prop i cut down and used in my nockoff drive

http://www.rcuniverse.com/forum/m_65...37/key_/tm.htm



these two are of headhunters metal 1/8 shaft converson
http://www.rcuniverse.com/forum/m_65...25/key_/tm.htm
http://www.rcuniverse.com/forum/m_65...27/key_/tm.htm

RE: Unofficial "NQD" Tear into Jetboat Thread
 

Thanks,
I just ordered some graupner ones from cornwall.
Mikev

RE: Unofficial "NQD" Tear into Jetboat Thread
 

Just a little update on my nqd boat. I had sucked up a rock last year and broke my impeller. I tried using a turned down abc hobby impeller for their jet ski. It did not perform as well, so I changed my motor to a higher torque motor. Still it seemed to cavitate more plus it took out the graupner ujoint. Replaced that with an all metal one from the apache. I finally gave up and put a replacement impeller from cornwall boats in the drive & it runs just like it did before i sucked the rock up. Below r some pics of turned down impeller set up and u joint.

RE: Unofficial "NQD" Tear into Jetboat Thread
 

man thats some cornage on that u-joint . but im glade cornwell came through for you and get you going again :D

RE: Unofficial "NQD" Tear into Jetboat Thread
 

I didn't have much success with my first one so I gave it to a friend. But I bought a second one to try some things on. First off this one had a solid metal connector from motor to drive shaft and the first one had a plastic u joint. The second one wouldn't even spin by hand because the outlet tube was out of round and the impeller was stuck. I found that the head of a mini mag flashlight was the right size to form the outlet back to it's proper shape. The cut out for the jet wasn't big enough so when i tried to put it back in it warped it. So a little dremmeling and it all fits. I used a bushing from a small motor with 2mm shaft to support the front of the drive shaft and decided to use a little 3000kv outrunner motor and esc from ebay to power it. Well it works real well. I've run 2s lipo at first to see how it does and then switched to 3s. With a 2200mah battery I get a very long run time and it is way faster than it needs to be. I've wanted a jet boat for a while and want to thank you guys for this thread.
MikeV

RE: Unofficial "NQD" Tear into Jetboat Thread
 

Sounds great, post some pics if you can. Yeah, I do mostly river/creek running myself and recently upgraded from a 2100 to a 3800KV (w/3s), so I should have no problems in the frothy stuff (if the impeller can handle it). I am a believer in higher volts=lower amps=longer run times with lower heat and am running Mystery 3s 2800ma 20C Lipos.

My metal shaft connector has oversized holes and causes vibration; I plan to change that for sure. And my impeller bushing wasn't even in the hole (butted against it) so I also had to redo that. Does your outrunner have an outer (non-moving) case? If not, it makes it difficult to cool effectively, and you might want to go to an inrunner/cooling tube/jacket if you end up cooking the present one.

For *****s and grins I changed the drivers heads to some I found on an an 'animated lowrider' toy (they already had a 'curve' in the neck area) and I left some wobble when fastening, so when you take off or turn, their heads move that way (whiplash). Here are some pics: