sundogz

I bought two a while ago to eval. They are a scaled down copy of the ABC jet ski drive, and suitable for smaller boats such as 12" or less. Cute little things, but I haven't installed one yet. But I see the NQD drive is for sale on ebay (China) for $19.95, so it is a better buy unless you have a small boat to fit.

dont slow down

I bought one to put into a Nikko boat I'm planning on using as a recovery boat. When I got it I realized it was much smaller than I thought. My boat is about 24" long so I decided to run two jets instead of 1. I'm currently in the process of rebuilding the rear part of the hull and transom to fit both. I had to cut out the original prop, shaft, and scag (fin on the bottom) I plan on using Traxxas 18t 380 motors to give them a little more power. I'm working on it today and will be cutting the bottom panel and then cuttin the holes for the jet drive. I'll post up some pics as it comes together.

Quicksilver

I'm back from the dead again.

Yay a nikko boat conversion! that was what got me obsessed with jets. Mine used the same darn jet drive I still use (29mm) with a 27t trinity motor and 8 cells. What a freaking monster that was, if I remember correctly it was like 14-15" I remember it took off once(using a mechanical speed control, hit a 39ft bayliner at my marina went under the bottom and flew up out the other side and luckily the motor then died, craziness.

Quicksilver

I've actually got a question, my IB3600's died from lack of use and I want to get the villain up and running again. What's a 16 cell equivalent lipo running price wise these days, with similar amp hours of the IB's?

Also what company is good now for nimh anymore? I remember when I bought the IB's like a decade ago, the IB's and GP's were getting tough to find.

God I'm so out of touch I dont even understand some of the acronyms you guys are using now, I feel very old lol.

sundogz

Long time gone, Quicksilver,. IB3600 equivalent - 16cell? Wasn't the IB3600 a 6 or 7 cell (7.4 to 8.4v) NIMH with 3600mah capacity and a 30C (thereabouts) discharge rating? A 2S (7.4v) lipo now will give you much more capacity or run time than the NIMH for the same weight (or the same capacity for less weight). You will be surprised and happy. Welcome back!

Quicksilver

I didn't buy packs. I made them so their two 8 cell packs. so whats that 6s-7s?

sundogz

16c NIMH at 1.2v/cell is 19.2v. A 1s lipo is 3.7v, so the closest match would be 5S (18.5v). [link=http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14968]This[/link] Turnigy 30C is a good buy and located at the U.S. Hobbyking warehouse.

Quicksilver

that isnt a bad price I might just buy that

thank you

Dongskie

http://www.youtube.com/watch?v=Wb_bg...&feature=g-upl

Madmax160764

NQD Jet boat dymo, new motor (4800Kv) and batteries Turnigy Nano-Tech 1.8

[youtube]http://www.youtube.com/watch?v=koS0yLIARtI[/youtube]

diy-pro

lovin it mad max sweet little jet drive :]]]

Madmax160764

NQd Tear-Into carnage bashing in pool.

[youtube]http://www.youtube.com/watch?v=PAyjhLO-WnE[/youtube]

pootis mcgootis

Hi All,

Just ordered twoKMB 28mm jet drives, always had an interest in building a dual jet hull. Any suggestions on a suitable hull? Interested in something that is widely available, even throughHK is fine just nothing caught my eye. Any suggestions towards motor/batt combos would be much appreciated as well. Thinking a low kV motor with a higher cell count LiPo...

Thanks,
P

Jay-Em

Informative thread.

However, I am still somewhat in the dark about the Graupner Mini-jet, and the ideal motors to run it.

At the moment I use the mini-jet, coupled with a hobbywing 10t BL 550 ( an SC motor) and it runs nice, cool, I get about 20min on a 4ah lipo. Hobbywing SC 75amp ESC keeps cool too. All of it watercooled though.
All of it is custom fit in a 48cm Kyosho WaveChopper jetski.

Point is, I see all sorts of ideal RPM proposed for the tiny jet, but no definitive rpm. The 550 is a 3500kv. I run it on 2s, and it seems to get pretty close to the full 25000 rpm. It has a habitof spinning-out, but a little judicious throttle control fixes that nice. It rides a nice, stable 5 degrees nose-up when on-plane, no porpoising whatsoever, so the pump gets primed well.

Is that 25000rpm too much? The speed is a sedate 25km/h or thereabout, since I go quite a bit faster than the Bicycles on the adjacent path of my favourite pond.
I tried 3s, but that only made a lot of noise and cavitation, speed only marginally increased.

In tne past I have experimented with the advised speed500 race (I guess it is a 21t 540) a Speed600race and a 17t double corally. All of those variations ran well, not really fast, but got very very hot, and killed their magnets, despite watercooling. The BL 550 is the first motor NOT to cook or burn... Must have done something right there

It just made me wonder: is that 25000 the limit of what the little Graupner jet can effectively use? In other words, 30kph is the end. Higher speed needs a bigger jet?

damfurst

There is only so much 19mm can do A bigger jet drive in the same size hull will make the hull go faster. This has been proven on the other jet drive thread with the Nqd tear into where some have put the bigger Graupner 29mm, Kehrer 28mm, and Abc Hobby 22mm. I hope this answers your question.

sundogz

So far as the Graupner and NQD drives, I have been advising that 3000kv on 3S and 4500kv on 2S seems to be tops with a 20mm motor. That comes out to 33000rpms unloaded. So you can get a little more speed than you have attained so far. But to get more speed yet, you'll need to go to a larger jet as Damfurst said, or go to a larger [link=http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8594]motor[/link] which will push through the 'envelope'. Or both. The larger motors seem less prone to the kv limitations of the smaller motors - where, in the upper 1/4 of the throttle range more throttle results in more noise, not more speed.

Jay-Em

hmm..okay.. The motor is a large 550. (3650/540L) meant for Stadium trucks, not a 20/380/400 class. it has plenty of oommph, It feels more like over-revving a too small prop.
Well.. I guess it's going to be Stabilit-hacking, and fitting a 28 Kehrer, then.

Ugh.. I had hoped to prevent having to cut'n grind away at the Stabilit mounds around the jet.. I only hope the not-so-impressive performance of the WaveChopper with a jet is not because of some design-flaw. Improbable, I know. I studied quite some Seadoos, and the kyo's hull is not bad at all, but one never knows.....

sundogz

My ABC Hobby Jet Ski's were factory equipped with 550 brushed motors (I don't know the rpm range) but the swap for the 28mm brushless motor brought much more speed and with it some aeration problems (another story) so made quite a difference. But in all fairness, they have 23mm impellers which might have helped a bit as well.

Jay-Em

Those ABC's seem to have been "put away" under the monniker "toy-grade", but, the more I read about them, the more impressing they become.
I searched e-bay, but the ABC's seem to be completely gone. Shame.

23mm You say? Hmm.. The Graupner is a 20mm. It could, indeed, explain the excessive aeration I get when putting 11.1v through the eazyrun 550..

Doesn't the ABC have some kind of baffle in the jet-exhaust? I distinctly remember a picture of it with some sort of rubber ring in the nozzle.

On another note: I fixed the spinning-out by copying a system straight from a Seadoo. Sponson-blades. It'll stÃ*ll spin-out when trying to turn really sharply on full throttle, but that's to be expected. Most speedboats do that. I am already happy enough that it'll corner at áll.

BIG22BIRD

My Feedback: (1)

well here is some updates, i have had a long r/c brake. and i finally put some batteries in my charger this morning, here are some progress pics. its dont now and loads of fun once again.

BIG22BIRD

My Feedback: (1)

some more progress, motor is mounted , shoegoo is my friend.





mounted the water pick -up. added some other stickers and a few coats of clear coat.






also added my grate.
i still need to mount my ride plate.

BIG22BIRD

My Feedback: (1)

BIG22BIRD

My Feedback: (1)

here is my water outlet, i used the exhaust pipes, instead of a hole out the back.

http://www.youtube.com/watch?v=M9TCJ...ature=youtu.be

sundogz

I like the driver - he looks ominous enough for sure. That boat will be another monster! The only reservation I have is the water through the headers is difficult to see to know if the cooling flow is sufficient. That is why I usually direct it up and out like a jet ski. Yep, shoe goo is good stuff, to be sure. Good job. Looking forward to a video of it in action.

seehuusen

hell yeah!! Looks great Big Bird I actually like the water out of the headers, hahaha Great ideas here