RE: Unofficial
Yes, I agree, and you need a water jacket on that motor, not a coil of tubing. You may also want to change to at least a 35A esc. I have a 60A in mine for a little headroom. Another perhaps cheaper route would be to go to a lower kv motor on 3S - 3200kv tops. Water jacket or tubing. That way you may get away with the 25A esc for a while as well. [:D]
Posted on: 5/30/2013 1:51 PM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11528108

RE: The Unofficial all things Jet drive thread
Another video showing how it heels over in tight turns. The bottom of the sponsons are at a slight 'V' angle which lifts one side a bit and digs in the other. I was a bit worried how that might affect things - that it might slide like an airboat. But it does the opposite. I can't detect any cavitation when one sponson is up, but the motor sound may be masking it. [youtube]http://www.youtube.com/watch?v=JLo6yT4F1iU[/youtube]
Posted on: 5/26/2013 9:53 AM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11523373

RE: The Unofficial all things Jet drive thread
I finally found time to maiden the JetCat conversion. I apologize for the crappy video. Note limited reverse capability of boat at start of video. 3500kv outrunners on 2S. A few bugs to work out, but all in all am happy with the arrangement. [youtube]http://www.youtube.com/watch?v=cwqkmU4CAfU[/youtube]
Posted on: 5/26/2013 9:48 AM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11523367

RE: The Unofficial all things Jet drive thread
Nice paint on the orange Davette! Have you had the blue one in the water yet? Looking forward to seeing videos. [:D]
Posted on: 5/22/2013 11:06 AM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11519396

RE: Unofficial
[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 ? [/quote] 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.
Posted on: 9/18/2012 6:00 AM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11232208

RE: Unofficial
[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? [/quote] 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!)
Posted on: 9/16/2012 7:20 AM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11229925

RE: Unofficial
[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. :-) [/quote] 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.
Posted on: 9/11/2012 7:18 AM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11224911

RE: Unofficial
Siftyish: She is a beauty! I can see that it must have taken a long time to build. Wow, if you ever decide to sell it.....[:D] Spectrumflux: Those boats that go real fast have larger motors in them. The 2040 gets the job done, but is a minimal motor and has to have water cooling to keep it from cooking. My larger [link=http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11179]outrunner[/link] isn't really pushed very hard and I don't use water cooling on it.
Posted on: 9/11/2012 6:04 AM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11224863

RE: Unofficial
[quote]ORIGINAL: spektrumFlux Just wondering ..... if using a 2600kv vs 4450kv motor (both 20mm Leopard motor) on the same boat, will there be any difference in the speed? [/quote] Yes, if you are using a 2S lipo, there will be quite a difference. 4500x7.4=33000rpm's target speed. 2600x7.4=19240rpm's and would be quite a bit slower. You might consider going to an outrunner or a 24 or 28mm motor (since you probably have no faith in the Leopard by now). I would try to get a free replacement for the bad motor first, since you already have a 20mm water jacket and 2S lipo. Surely you won't get [i]another[/i] lemon!
Posted on: 9/10/2012 7:42 PM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11224477

RE: Unofficial
[quote]ORIGINAL: spektrumFlux my very first RC boat and already wasted 2 motors and hours of frustration. :-( btw, what's the difference if using those lower kv Motor like 2600kv type as compared to 4450kv? [/quote] Yes, I can see your frustration, and on a motor that I suggested to use! But I don't believe it happened because of the kv range. People have been using the 4800kv motors but notice a dead spot in the upper 1/4 throttle segment, so this 4450kv should have eliminated that problem. But to answer your question, a lower kv motor will use less amps to get the job done - and yes, high amps are what killed your motor(s), but we don't know why they drew so many amps. If you decide to go with a 3S system, you want to stay around 3000kv unless you go with a larger motor like a 28mm. With a larger motor the kv range is not so critical, as it will push through the 'envelope' with the extra power available. But it is still advisable to stay in those kv ranges for best balance of throttle response (2s-4500kv, 3s-3000kv.)
Posted on: 9/10/2012 6:01 AM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11223549

RE: Unofficial
My best guess is that it was a defective motor. Maybe someone else will chime in here.
Posted on: 9/9/2012 7:50 PM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11223273

RE: Unofficial
[quote]ORIGINAL: spektrumFlux My 1st run is not ideal too as placed the water inlet in wrong place and no water flow into the system which resulted in the Motor malfunction after about 5 mins of run. For the 2nd run, I have changed the water inlet location, borrowed an identical Motor from friend to test it out. The water flow is fine through the system (In-Motor-ESC-Out) then smoke after 1~2 mins run..... [/quote] Did the first motor also melt the motor wires? On your second run, could you see a stream of water coming from the outlet while you were running? BTW, the plumbing should go: IN-ESC-MOTOR-OUT. But that didn't cause your problem.
Posted on: 9/9/2012 12:28 PM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11222694

RE: Need help on 40c, 50c, 65+c ratings..
[quote]ORIGINAL: ryan_t888 My words are carefully chosen. By saying you [i]don't recommend anything anymore[/i] makes me aware that you really do not understand how it works. [/quote] LOL, Nope, I said that I "never recommended anything to anyone" (in this thread). You should perhaps pay more attention. Your assumption that I don't understand "how it works" is also unfounded - probably due to lack of feedback. But for the record (everything is on record, you know) I generally recommend the highest "C" rating that you can afford.
Posted on: 9/9/2012 12:12 PM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11222869

RE: Need help on 40c, 50c, 65+c ratings..
[quote]ORIGINAL: ryan_t888 "I've not once said you are wrong" ...."It seems you are in favor of micro managing the ''C'' rating and I think THAT is wrong. What are you recommending the original poster to do?" [/quote] In post 2, Norbique told the OP "You will not fry anything because of high C rating pack", then Ryan chimed in with "Yes, a higher C rating is ALWAYS better...". Such cut and dry statements brought to mind that this is not always the case - using Minicats experience as an example. I never recommended anything to anyone, (or asked anything - thank you anyways, Ohain). Making assumptions, implications and lashing out at me is not helping the OP, I 'm sure! My 'suggestion' would be for you to refocus, and realize when you use words such as never, always, none, etc. that they are powerful words and a little more thought may be necessary. Nothing personal.
Posted on: 9/9/2012 7:52 AM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11222684

RE: Unofficial
How did it run (when you first ran it)?
Posted on: 9/8/2012 9:47 PM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11222416

RE: Need help on 40c, 50c, 65+c ratings..
Ryan, no offense here. It's just that you verified what I had implied earlier - that using a higher 'C' rated lipo may fry your esc under the right circumstances. But at the same time, you imply that I was wrong. LTM.
Posted on: 9/8/2012 9:42 PM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11222410

RE: Need help on 40c, 50c, 65+c ratings..
[quote]ORIGINAL: ryan_t888 People then used up to date packs with higher C ratings which increased voltage and amperage ultimately destroying minicats ESC. [/quote] LOL, So evidently, a motor [i]can[/i] ask for more amps than the esc is able to handle.
Posted on: 9/8/2012 8:10 PM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11222340

RE: Unofficial
Fried to a crisp, aren't they? Well, there's no tellin'. How did it run?! Maybe you had an obstruction in the intake (leaves, algae, etc.) and didn't know it, so kept running it hard to keep up. That combo was right in the sweet range (4450kv on 2S) for this pump.
Posted on: 9/8/2012 1:27 PM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11221974

RE: where can i get
[quote]ORIGINAL: w3bby The Jettec drive is currently probably the best drive available. Whilst the body is composite the rest isn't. Check out [link=http://www.rcuniverse.com/forum/m_9361615/tm.htm]this thread.[/link] There is also a [link=http://modeljetboat.com/forum/]jet boat forum.[/link] [/quote] Yes, it looks to be nicely made. Do you know what size impeller it uses? For some reason I can't log onto modeljetboat.com anymore, so can't see pics. And they aren't accepting applications, so can't change passwords. Too bad, this is a good site for jet boaters with fresh ideas. Thx, w3bby.
Posted on: 9/7/2012 7:58 AM by Author "sundogz" in the forum "RC Boats General Discussion"
http://www.rcuniverse.com/forum/fb.asp?m=11220656

RE: Unofficial
[quote]ORIGINAL: spektrumFlux did not notice any resistence and I'm using a 2S 40~80C Lipo battery. very puzzled why the wire could burn. [/quote] Turn the coupling with your finger, it should be smooth with no resistance for a full turn. There are several things that can hang up - the loading ramp fit (if you removed the jet drive), the shaft could have come forward when you attached the coupling, allowing the shaft to come out of the rear bushing, a piece of plastic caused by the injection moulding process that wasn't fully removed, etc. One other thing is too small or inadequate connectors can cause high heat. And it could have been a bad motor - it happens now and then. Do you have any pics - they might explain more.
Posted on: 9/7/2012 6:21 AM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11220561

RE: where can i get
Wow, I just checked Jettech and their jet drive lists for $849! That's a little high for a plastic pump. I noticed they don't say what size the impeller is. There are also 19mm jet drives available on ebay now for about $25 For the NQD 757 (a copy of the Graupner minijet) and the replacement (13mm) pump for the Proboat recovery decoy costs a little less from any Proboat supplier.
Posted on: 9/6/2012 1:52 PM by Author "sundogz" in the forum "RC Boats General Discussion"
http://www.rcuniverse.com/forum/fb.asp?m=11219881

RE: Need help on 40c, 50c, 65+c ratings..
[quote]ORIGINAL: norbique You will not fry anything because of high C rating pack. You will sooner fry things with a badly set up or too big prop. If you can, try running the boat with a smaller prop first then check motor/ESC/battery temps and if everything is OK you can go for a bigger prop, run check temps again. [/quote] This would seem so, but [link=http://www.minicatracingusa.com]Minicat Racing[/link] voids your warranty if you use over a 30C lipo on their [link=http://www.minicatracingusa.com/]30a esc. [/link] So evidently, a motor can ask for more amps than the esc is able to handle.
Posted on: 9/6/2012 1:27 PM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11219849

RE: Unofficial
Sounds like you have a couple of different problems. The shaft bore tolerance seems to be critical in this jet drive and wear can lead to air entry causing loss of prime, as well as water entry when setting still. This is why it is so important to keep the shaft lubed with a good waterproof marine grease. Though some have relined with success, at this point I would buy another pump,[i] keep the shaft greased[/i] and be done with it. Your motor seems too high a KV for 3S. Go with something around 3000kv and it should settle down without much (if any) loss in speed. Something I found out a while back was this boat goes through stages with increased speed. Given more speed, it porpoises, a little more speed and it settles down. You're in-between with your setup is all. Good luck!
Posted on: 9/6/2012 7:38 AM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11219423

RE: Unofficial
[quote]ORIGINAL: damfurst Looking at doing another twin jet boat. Thinking about an Impulse 26 hull for that one. Kind of been out of touch for a while looking to get back into hobby again. [/quote] Glad to hear it. The Impulse would be a good candidate for a twin setup. I've been thinking of putting a couple Duck drives in the sponsons of a small non-stepped cat hull, but haven't found the right hull yet.
Posted on: 8/27/2012 7:56 PM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11208470

RE: Unofficial
[quote]ORIGINAL: damfurst I have the Graupner one in my Nqd as well. It's pretty much as deadrock said not much difference in performance. The Graupner does have a weaker motor mount, but is easier to do the bearing mod to. [/quote] Glad to see that you're 'lurking about' there Wes. Any new projects?
Posted on: 8/25/2012 8:04 AM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11205448

RE: Unofficial
I think what causes this is the intake ramp gets deformed (squeezed) by the screws into a narrower 'U' and the impeller hits the sides. You can trim the offending area down, or make a shim out of a credit card and insert it so that it prevents the ramp from going all the way back, thus preventing it from hitting. Or you can overfill the cavity in the end of the ramp with JB Weld so it provides the needed clearance when installed. That is as far as I would pursue 'perfection' because you can get caught up in trying to get everything trimmed, sanded and smooth but the results will be very similar and not worth the added effort, IMO. If I were racing these, I would use a dowel and vise to reform the 'U' shape wider, fill the cavity with epoxy to keep it that way, and trim the sides to fit. Then I'd sand the blunt leading edge of the ramp to a sharp wedge and remove all mold marks from the intake chute. Or better yet, install a Graupner mini jet as the quality is much better. You can see how it's easy to get caught up in all this.
Posted on: 8/21/2012 10:05 PM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11201716

RE: Unofficial
No, it's easier than that. When you click 'reply' it goes to where you enter text. and just below that, you'll see "click here to upload images and files". Take it from there.
Posted on: 8/21/2012 11:53 AM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11201076

RE: Unofficial
I have recently had problems with the email link to this forum not taking me here - I have to manually get on and locate this thread. They must be experiencing problems of some kind. On gluing the jet to the hull, if it doesn't leak (around the jet body) I don't remove it - there is no need to. But if it leaks, I'll remove the jet body and reinstall it and the intake ramp permanently, eliminating any potential leaks. I used to use superglue, but it outgasses and leaves a white discoloration, so I now use a 2 part epoxy made for plastic. I then install the stator housing to the transom with silicone. I have never 'worn out' a jet drive bore, but if it was to happen, I can re-line it in the hull easily enough with a drill bit and 1/8" brass tubing (if the hull was still in decent shape by then). And let's face it - it's just a $45 boat. If something went bad wrong, I'd just buy another boat. Preacher, the intake ramp is installed fully to the rear - the bottom two screws of the stator housing pull it into place. What needs to be trimmed? Pics?
Posted on: 8/20/2012 9:18 PM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11200467

RE: Unofficial
The [link=http://www.hobbyking.com/hobbyking/store/__11984__Turnigy_Taipan_Fiberglass_V_Hull_385mm_Hull_Only_.html]Turnigy Taipan[/link] and the [link=http://www.hobbyking.com/hobbyking/store/__11983__Turnigy_Cobra_Fiberglass_V_Hull_385mm_Hull_Only_.html]Turnigy Cobra[/link] both are fiberglass and have 90 degree transoms, so would be good candidates for twin 'Duck' drives or an NQD/Graupner mini drive.
Posted on: 8/20/2012 12:48 PM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11199887

RE: Unofficial
[quote]ORIGINAL: Toyotatrucks83 Just ran across this. Was wondering if it is new news in this forum? http://www.proboatmodels.com/Products/Default.aspx?ProdID=PRB3656 [/quote] No, the jet drive for the Duck Decoy recovery 'boat' is quite small. It has a 13mm impeller and is suitable for micro size boats (9" to 16" or thereabouts). You'd need two of these drives to get the power of an NQD or Graupner mini (19mm) drive. Which, by the way would be pretty cool - I don't think a twin micro has been done in this thread. Area = Pi x Radius squared Radius of 13=6.5; Pi=3.14 3.14x (6.5x6.5) 42.25=132.67sqmm Radius of 19=9.5 3.14x (9.5x9.5)=283.4 sqmm
Posted on: 8/20/2012 11:44 AM by Author "sundogz" in the forum "Speed - Electric"
http://www.rcuniverse.com/forum/fb.asp?m=11199818