The Unofficial all things Jet drive thread
#2552
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RE: The Unofficial all things Jet drive thread
I was only joking about the race but you never know.
Really i'm just hoping i didn't over do the motor it is a bit of a monster from all accounts, still i thought i was better to have too much power than not enough [&:]
I think my pickup will work, i just get less flow than expected a trickle at the speed i've tested rather than the spray i thought i might get, but that could be a good thing anyway seems to cool the pipe work pretty well. Bit concerned about having to move it as i've already used bits from 2 [:@] jetdrive kits to finish this boat, grrrrr at graupners quality.
Really i'm just hoping i didn't over do the motor it is a bit of a monster from all accounts, still i thought i was better to have too much power than not enough [&:]
I think my pickup will work, i just get less flow than expected a trickle at the speed i've tested rather than the spray i thought i might get, but that could be a good thing anyway seems to cool the pipe work pretty well. Bit concerned about having to move it as i've already used bits from 2 [:@] jetdrive kits to finish this boat, grrrrr at graupners quality.
#2555
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RE: The Unofficial all things Jet drive thread
well after going throw my high amp lipos i have found i need some higer amp packs i had a 4s 3000mah and a 2s 2000 mah pak bit the dust they both swalled . any ideas i thank im in the 45-60 amp range going by the temps of the motor and esc .
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RE: The Unofficial all things Jet drive thread
Dragonfire the boat with lid and an esc but not batteries weighs in at 3lb9.25oz or 1.625kg if you prefer
Not had any joy looking for impellers, but found some fun other forums e.g. rocket boats
Anyone know where i can find out about DIY esc's??
Not had any joy looking for impellers, but found some fun other forums e.g. rocket boats
Anyone know where i can find out about DIY esc's??
#2559
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RE: The Unofficial all things Jet drive thread
Wow amazing what a bit of aluminium tube and a stupidly big motor does huh, oh well it seems like a good weight when i'm holding it. I suppose there is a fair bit of epoxy and glass fibre in there too.
Wasn't trying to save weight if i'm honest didn't really think about it till you asked.
I guess it's because i'm not really planning to use it on rapids, or trying to go fast, just wanted something a bit different (DOH!) that was reasonable quick.
Wasn't trying to save weight if i'm honest didn't really think about it till you asked.
I guess it's because i'm not really planning to use it on rapids, or trying to go fast, just wanted something a bit different (DOH!) that was reasonable quick.
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RE: The Unofficial all things Jet drive thread
the reson i ask is your useing nicd battery or bricks as i call them . for go resolts in speed and runtime you wont it as light as you can get it . but i thank your pretty good i try to keep my boats around 5lb with this drive . but even if your a little over you have the larger motor to make up for it . see i wont this boat to be equaly fast as big blue was on 4s . but since this hull is shorter and the 3 blade impeller i have i thank i mite blow the deck off of blue
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RE: The Unofficial all things Jet drive thread
Was going to go for lipo but read up about cells burning, exploding etc. and got too scared what with 2 small children in the house, so went for the slightly safer option.
As i say not looking for super fast, i would have saved loads of money and effort and just junked the electrics and replaced with brushless setup.
I was happy enough with it as it was RTR with the 540 motor it had, jet drive was just fun a project and something different, at least theres only 3 of these in the world now LOL.
It's 5lb 7oz or 2.48kg with the batteries, oh well not quite light enough [X(]
As i say not looking for super fast, i would have saved loads of money and effort and just junked the electrics and replaced with brushless setup.
I was happy enough with it as it was RTR with the 540 motor it had, jet drive was just fun a project and something different, at least theres only 3 of these in the world now LOL.
It's 5lb 7oz or 2.48kg with the batteries, oh well not quite light enough [X(]
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RE: The Unofficial all things Jet drive thread
thats not bad like i said you have the ex torq to move it . you mite be supreised at what speed youll get . im thanking of tring her out on two nicd pack since i need some higher amp lipos then what i have .
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RE: The Unofficial all things Jet drive thread
vinnyst,
I've looked up DIY brushless speed controllers before, but I would rate them as an advanced electronics construction project at the moment. You have to have a microcontroller to sequence the pulses to the coil drivers, and it has to constantly monitor the feedback voltages, even at very high RPM. There is some free object code out there, but you need to be able to download the program code into the microcontroller too.
All quite a big ask, unless you are already pretty good at electronics. I had my own electronics and SW company for 4 years, and I've considered one, but it's cheaper to buy them out of China, than it is to buy the components individually, to make the circuitboard, etc etc.
For RC, you want high density SMD construction, and that's another challenge for a beginner, to solder small fine pitch packages without developing solder bridges where they oughtn't be !
I do have one brushess project in mind, but it's more likely to be around the end of this year, and it wouldn't be free source or design.
I've looked up DIY brushless speed controllers before, but I would rate them as an advanced electronics construction project at the moment. You have to have a microcontroller to sequence the pulses to the coil drivers, and it has to constantly monitor the feedback voltages, even at very high RPM. There is some free object code out there, but you need to be able to download the program code into the microcontroller too.
All quite a big ask, unless you are already pretty good at electronics. I had my own electronics and SW company for 4 years, and I've considered one, but it's cheaper to buy them out of China, than it is to buy the components individually, to make the circuitboard, etc etc.
For RC, you want high density SMD construction, and that's another challenge for a beginner, to solder small fine pitch packages without developing solder bridges where they oughtn't be !
I do have one brushess project in mind, but it's more likely to be around the end of this year, and it wouldn't be free source or design.
#2564
RE: The Unofficial all things Jet drive thread
Yep, both of those boats are looking good. Vinnie: don't worry about low flow on your cooling system. If it's flowing, it's cooling. It doesn't take much. My knockoff just produces a trickle at speed, but the motor never gets more than warm. That location (for the pickup) should be fine.
#2565
RE: The Unofficial all things Jet drive thread
And if you don't want the worry of Lipos (much recommended) you might try NiMh instead of Nicads - they hold more power per weight and can be charged with the same charger. I use them on my RC 4 wheeler for longer runtimes.
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RE: The Unofficial all things Jet drive thread
Actually I wouldn't worry so much about lipo's. The only time they seem to explode now would be if you over discharge them and try to charge them after. The water being able to get into the packs seem to be corrected at manufacturing. I think I have 20-30lipo's, only time ever with the fire is trying to save money and charger her up after discharging pack to near zero. Now I would just throw it in the garbage. It is the best technology for dollar and weight and amp draw. But you do need to ensure the lipo can handle the draw, which means u need to know the draw, also motor can suck more energy(nimh/nicd generally can't fully supply motor) and run at full potential.
Ivan.
Ivan.
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RE: The Unofficial all things Jet drive thread
im staying with lipos i just wont to get this boat in the water . thats why im going to throw my nicad at her . it did ok on my 3s max amp packs there rated for 25c
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RE: The Unofficial all things Jet drive thread
Hey Dragon & Vinny your boats are looking good!! I burned out my motor in my Jet ski, so am currently replacing with Emp 3200kv motor like in the Brick. We'll see how that turns out.
I have wondered too if Lipo's are or arn't waterproof? You guys know more about that than I.
I have wondered too if Lipo's are or arn't waterproof? You guys know more about that than I.
#2570
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RE: The Unofficial all things Jet drive thread
Cheers for the various info guys.
Thought the esc was a bit of challenge just a bit concerned with the one i had/am getting back as it has several boards and not sure how to make sure all components are suitably cool.
Water should be fine as you say any flow should do in fact too fast a flow would be detrimental to optimal cooling, my submersible/rescue (if your lucky) boat only produces a trickle and is fine.
The batteries i have are nimh anyway so no probs, i'm happy with them and maybe when i have funds again i'll invest in lipo, i was originally going to go lipo and had a different motor i would have used that was a xl version of the current motor with a lower Kv rating, so saved some weight there anyway.
Thought the esc was a bit of challenge just a bit concerned with the one i had/am getting back as it has several boards and not sure how to make sure all components are suitably cool.
Water should be fine as you say any flow should do in fact too fast a flow would be detrimental to optimal cooling, my submersible/rescue (if your lucky) boat only produces a trickle and is fine.
The batteries i have are nimh anyway so no probs, i'm happy with them and maybe when i have funds again i'll invest in lipo, i was originally going to go lipo and had a different motor i would have used that was a xl version of the current motor with a lower Kv rating, so saved some weight there anyway.
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RE: The Unofficial all things Jet drive thread
Vinny the part u need to cool on esc is the aluminum on the fets. Cool the aluminum. Don't worry bout rest of stuff, although 7 boards sounds weird. It has reverse or something?
Ivan.
Ivan.
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RE: The Unofficial all things Jet drive thread
No not seven, several. Think it was four don't have in my hand at the minute.
The reason i'm concerned is the my Dynam esc i modified to have a finned heatsink, had a warped board from new which meant only 2 fets where touching the alu. just worried this could be the same which might have what caused it to fail.
It's a Hextronic hxt120A in case anyone has any experience of them.
The reason i'm concerned is the my Dynam esc i modified to have a finned heatsink, had a warped board from new which meant only 2 fets where touching the alu. just worried this could be the same which might have what caused it to fail.
It's a Hextronic hxt120A in case anyone has any experience of them.
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RE: The Unofficial all things Jet drive thread
Get cpu paste, that's what is generally under the aluminum to transfer heat from fet to metal. Another thing you can try is goop around the edges and press hard on aluminum as it sets(sit book on it), this will prevent fets burning up with contact to water as that's generally how you burn out an esc also the heat like ya said. Or get some heat shrink that goes over whole thing.
#2574
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RE: The Unofficial all things Jet drive thread
I'll post a pic when i get the replacement you'll see what i mean it's pretty odd i haven't seem multi board esc's before.
Suppose i could force thermal compound through gaps to fill all the voids between boards. Don't really want to mess with it incase this one dies too.
Suppose i could force thermal compound through gaps to fill all the voids between boards. Don't really want to mess with it incase this one dies too.
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RE: The Unofficial all things Jet drive thread
hey could I use two mini graupner jet drives insted of one like big22bird,would it be easyer to do two mini ones then one
thanks
thanks