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Old Nov 12, 2012, 01:11 PM
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Tiernan85's Avatar
Ireland, Leitrim
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Servo thoughts

Hi again fellas,

Still waiting for my boat, I hate the waiting game.

My next question is servos. I have a couple here I can use but I'm just wondering what your thoughts are.

The one I initially thought I would use is a Hitec 5645 which I know will be plenty for the simple task. Probable overkill. It's a spare for my scale truck.

Specs:
Motor Type: 3 Pole
Bearing Type: Dual Ball Bearing
Speed (4.8V/6.0V): 0.23 / 0.18
Torque oz./in. (4.8V/6.0V): 143 / 168
Torque kg./cm. (4.8V/6.0V): 10.3 / 12.1
Size in Inches: 1.59 x 0.77 x 1.48
Size in Millimeters: 40.39 x 19.56 x 37.59
Weight ounces: 2.11
Weight grams: 59.82

I also have a handful of Hitec HS-55 mini servos that I use with my planes. These ones are obviously a lot less powerful in comparison to the above. My question though is it still powerful enough? How much power is needed to turn the jet when it has the water pressure on it?

Specs:
Motor Type: Coreless
Bearing Type: None
Speed (4.8V/6.0V): 0.17 / 0.14 sec @ 60 deg.
Torque oz./in. (4.8V/6.0V): 15 / 18
Torque kg./cm. (4.8V/6.0V): 1.08 / 1.30
Size in Inches: 0.89 x 0.45 x 0.94
Size in Millimeters: 22.61 x 11.43 x 23.88
Weight ounces: 0.28
Weight grams: 7.94
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Old Nov 12, 2012, 03:05 PM
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Ayrshire, Scotland
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Quote:
Originally Posted by Tiernan85 View Post
Hi again fellas,
My next question is servos.
Either would do. Lots of people are using 9g servos from the likes of HK, which are probably not as efficient as the Hitec one, so the Hitec would do the job. Just make sure to remove any flash on the mouldings so the nozzle moves freely (doesn't need to be loose - just free to move when the servo commands it). On the other hand, while there is something to be said for weight saving it is not quite as important in a boat of this type as it is in a small electric plane - and you would be putting the weight at the back, which is the part you need to keep in the water to keep water flowing through the jet. And in any case, if you use a watercooled ESC it may weigh more than the ones you are used to from your aircraft, and the bigger servo will probably balance the weight side to side.

Under the circumstances I might use the big servo if is it going spare. Whichever you use, bear in mind that you only need about 5mm of travel to go from lock to lock so one or the other may be more suitable for that reason. I know you can restrict movement at the Tx but it's never as good as doing it by a mechanical linkage - ie a very short arm on the servo.
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Last edited by madbugger; Nov 12, 2012 at 06:31 PM.
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Old Nov 12, 2012, 03:40 PM
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Ireland, Leitrim
Joined Oct 2009
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Cheers madbugger, might just go with the bigger one than seeing as I am running a watercooled ESC. I have loads of servo horns so I'll make sure to use a small one or even drill a hole if need be.

Fingers crossed the boat and remaining bits show up tomorrow as I'm off on wednesday and can get her put together. Probably won't even run it in stock trim.

Thanks again.
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Old Nov 12, 2012, 04:33 PM
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Canada, ON, Whitby
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Quote:
Originally Posted by Tiernan85 View Post
I also have a handful of Hitec HS-55 mini servos that I use with my planes. These ones are obviously a lot less powerful in comparison to the above. My question though is it still powerful enough? How much power is needed to turn the jet when it has the water pressure on it?
I'm running a $3 HobbyKing 9g servo in mine without any issues, a real HS-55 will be totally fine too.
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Old Nov 12, 2012, 06:26 PM
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Yeah, me, a have a full size 3003 futaba, its what I had layin around, guys are using minis with no issue, tho..me, I'm old school, more is better..

DO make sure you dont over travel the linkage, set your trim accordingly, or, you can snap the steering arm off the nozzle..I am using the lowest hole on the servo arm, WITH some dual rate adjustment still, and its stop to stop..
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Old Nov 12, 2012, 06:45 PM
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Tiernan 85 / Preceding 2 posts go to prove what I was saying. Either servo would do. I've got a mini in one of mine and and old Fut 3003 in the other. When I get round to completing the SicRC one I'll just use whatever is at the top of the spares box at the time.

chidago / One thing about the old Futaba ones - they seem to be difficult to kill - cope with getting soaked etc.even without waterproofing - although a coating of Plastidip is always a good 'belt and braces' move.

chidago, any news on the kmb front?
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Old Nov 12, 2012, 08:28 PM
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Joined Dec 2011
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My NQD Build buddy codes

My NQD Build buddy codes

HK-B70A Hobbyking SS Boat Series 70A ESC
http://www.hobbyking.com/buddy.asp?c...D-CC8590BA5135

TGY-390DMH TGY-390DMH High Performance MG Digital Servo
http://www.hobbyking.com/buddy.asp?c...2-6B2D5D1F1A79

4800-2040SL 2040SL 4800kv Brushless Inrunner (WaterCooled)
http://www.hobbyking.com/buddy.asp?c...9-4980550B8782

Hope my build goes well!!!
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Old Nov 13, 2012, 08:53 AM
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Mad, still waitin for a reply from them, he aint on the quick side..
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Old Nov 13, 2012, 10:14 AM
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Joined Jul 2006
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jet thread

Forget the 70 hk esc. I read there there seems to be alot of questions pretaining to operation of the 70 esc. Now for $10.00, i'd get the HK 115/125 esc and never look back. I have one and runs great. Never know when you might need a bigger esc. Before you plug battery in , hook up everything first and pull trigger to for forward motion and release to neutral and then hook up battery and ready to go and no program card needed as it is plug and play.
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Old Nov 13, 2012, 12:43 PM
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Vancouver, BC
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Those ESC's are way overkill, especially with a 2040 motor.
My 2448 on 3S draws maybe 10-15A at the most. The SeaKing 35A is perfect for these boats.
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Old Nov 13, 2012, 01:41 PM
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My response from kmb..

Angebot - Offer Nr. 2012079
Menge Art.-Nr. Text Einzelpreis

Gesamtpreis

1,00 Stück JSE111 Jet-Sprint-Boot, eck.Cockpit kompl.mit Einsatz
incl. 1 x 28-mm-Jet, rollbar B01, motordummy, 2 seats
176,47 176,47
1,00 Stück B02 Überrollbügel - Doppelverstrebung f. Sprint-Boot
rollbar
12,18 12,18
1,00 Stück JET2805a rundes Steuerteil 6,72 6,72
1,00 Stück JET2808 28-mm-Jet-Stator (Ersatzteil) 2,52 2,52
1,00 Stück JET2809 28-mm-Jet-Impeller auf Welle (Ersatzteil) 8,40 8,40
1,00 Stück JET2810 28-mm-Jet-Kugellager (Ersatzteil) 2,77 2,77
1,00 Stück MH12 Alu-Adapterflansch f. Mot. 25mm Lochabstand 10,92 10,92
1,00 Stück KUP2 Hochlastkupplung 5 / 4 mm
Power Grip Coupling 5 / 4 mm
11,34 11,34
1,00 Stück SER55 Servoansteuerung rechts/links für 1 Jet
1x Servohalter SER04, 1x Bowdenzug BOW1, 1x
Kugelkopfgelenke KG02, 2x Gestängeverbinder
ZUB.GV1.1
7,14 7,14
1,00 Stück B03 Überrollbügel - für Stingray
part of the rollbar (DieHard)
0,00 0,00
1,00 Stück ZUB32 Steuerrad 32 mm, Kunststoff 0,00 0,00
Zwischensumme 238,46
zzgl. Handling + Shipping taxfree / Versandkosten Ausland steuerfrei 39,60
Gesamtbetrag 278,06


Thats $ 353.30 to me..

No motor, or radio gear at all in that, just boat, all fittings from them, extra stator, impeller, bearings, etc.
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Old Nov 13, 2012, 03:53 PM
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Quote:
Originally Posted by Firehawk989 View Post
Those ESC's are way overkill, especially with a 2040 motor.
My 2448 on 3S draws maybe 10-15A at the most. The SeaKing 35A is perfect for these boats.

Hey

Sorry I never build anything to stay where it is so i pretty much buy bigger esc's encase i transplant them into something else bigger, You can always go big and use 10% but you cant go small and use 200% as in the 35amp vs 70amp

Just my 2 c

EDIT - Sorry I am also buying a bigger jet eventually and at the same time replacing the motor and going for 2x3cell batteries in parallel or maybe even the 2x2cell in series, I am using all Traxxas connections and have the adapters already.
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Old Nov 13, 2012, 04:13 PM
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Tiernan85's Avatar
Ireland, Leitrim
Joined Oct 2009
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Thanks for the previous replies fellas.

My question now is where can a get a coupler that is 2.3 to 2.3?

My boat came in today. I'm happy it's here but it's got some work to be done lol.

Some misc melted plastic on it here and there, but it's only cosmetic.

I tore everything out of it right away. Decided to just give the jet a quick blip to ensure everything is ok... Oh boy... talk about VIBRATIONS!!! Some minor impeller damage occurred even with the quick little blip the throttle got. I have a couple spare though.

I've tracked it down to the coupler. It's WAY outta whack. I measured the wall thickness on one side as it even looked visually off. One side measured 2.59mm and the other side 2.36mm. So someone had a few too many when drilling it out lol.

I'm hoping that's the only thing that's wrong and that the shaft is still straight as it seemed to have taken some serious abuse in those couple seconds..

Perhaps I'll just buy a spare jet drive and hope that coupler is better? The coupler I found on ebay is 11 bucks shipped. I can get a complete jet unit for24 shipped.
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Old Nov 13, 2012, 05:00 PM
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Ayrshire, Scotland
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Quote:
Originally Posted by Firehawk989 View Post
Those ESC's are way overkill, especially with a 2040 motor.
My 2448 on 3S draws maybe 10-15A at the most. The SeaKing 35A is perfect for these boats.
As you would say, Indeed! And while we're at it, the 4800kv motor seems like overkill as well, but it takes all sorts.
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Old Nov 13, 2012, 05:20 PM
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Ayrshire, Scotland
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Quote:
Originally Posted by chidago View Post
My response from kmb.
Thats $ 353.30 to me.
I know their drives are good stuff, and on a Scale Models website (not RCGroups) I found a complimentary review of one of their scale hulls. Even so, that's more than I would be prepared to pay for a model which at, the end of the day, won't be anything like as fast as your 'Predator' prop-drive boat. And as you said before, while one can rock-climb alone it's no fun on a lake unless some of your friends build one as well. More chance of that with NQD's than with something which will cost $353 dry, and almost twice that by the time you have given it the motor, ESC and LiPos it deserves.

After all while I, like you, am old school (as in more is better, although you missed out the next line - 'and too much is just enough!') it is nevertheless the case that most full-size and model racing formula depend on restricting things in one way or another to make for fairer and more affordable racing. I think the sight of 6 NQDS racing round a lake course would beat the sight of one KMB boat all on its lonesome - no matter how awesome it was.
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Last edited by madbugger; Nov 13, 2012 at 06:56 PM.
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