headhunter23

Well here's the updated photos and video, was done kinda quick except for gluing in the plate and drive setup. Took a lot of time doing that plus had to actually hold it because the hull had changed a bit since cutting it and pulling all the glue off. Originally when I did the cut for the aluminum plate the hull actually became narrow. Didn't realize this at the time until I tried gluing the top on. Anyways looks a lot better. Still had an issue with the porpoising but more than likely it's just the weight of the batteries, had them all the way in the back, had made some foam spacers which worked in keeping them in place before last gutting, just forgot to bring em to the river.

Also changed the steering a bit, will be taking advantage of the dual steering but because I did it quickly it only worked good enough. Light is gone so quick these days...

The boat hitchs up on rocks a lot now, before you could glide across stuff, going to try smoothing and add some sort of smoot surface to the rails before grinding them completely off. Anyone know where I can get teflon in a can?

That's about it so far, will post again with rails adjustments.

Oh yea, added a photo of the backyard, looks like no more running in the pond till she warms up.

headhunter23

More pics, will edit this post with video links once youtube finishes checking em.

Edit point:

http://www.youtube.com/watch?v=iYu3FF0roJw

http://www.youtube.com/watch?v=DMDXfLcuKcY

Yea on 14.8v it runs pretty good, I would say it's *****g out the drive personally because the other motor did about the same speed. And after the 6 min before the damn set screw managed to losen, there was literly no heat. Was almost cold, so not sure how many amps it's trying to use but so far most of the brushless haven't really heated up at all except for the 3200 25a when it was pushing 4s 5000mah lipo in the hammer with no gear reduction.

Will have better videos next time, was nice having a video guy (that wasn't me driving, that was comport getting a taste). Will have to back up a bit, seems a little too close.

DRAGONFIRE81M

man you could hear that you pushing 14.8 it sound more alive how was the temp on that outrunner. was you able to make that jump before thats sweet

headhunter23

Cool, got my scale finally. Cheap but seems to be accurate enough. Scale increases by 2 gram increments so it doesn't give ya the exact but weight is within 1 gram either way.

Anyways did a scale of old red brushless with cooling, total weight 118 grams this includes wires for batteries and wire for esc.

New brushless no cooling 30-32grams. soo seems like it's actually 31 this includes wires for batteries and wire for esc.

servo 6g, as advertised.

weighed each battery, one was 90g the other was 88g so would average to 89g for a 2s 2000mah 12c lipo.

The original 11.1v lipo 1200mah batteries weighed in at 78 and 80 so averaged to 79grams, the wires were shortened by an in.

ummmm... boat with drive installed, plate, and servo holder... 124g, oh and no top.

jr receiver 310 is 20g.

Reduction in screws for steering and shortened rods 6g.

So estimated reduction of weight to going back to original... Lost at least 93g not including the water going through the hose. Not bad! Although I probably gained 15-20g by adding more aluminum. Anyways that's the same weight of another 2s 2000mah battery!! Am doing more work to it tonight, might be able to trim down the strake blades on the bottom tonight but it depends on how much patience I have. Which isn't much seeing that it's a Friday and my back has been pissing me off with this killer headache over the last three days. Anyways thought this would be interesting to some. Seems every gram really does count. Going to have to add that to my sign off for my posts!

Ivan.

goldendesign04

dang boy you could get a jewelers scale large enough to weigh any boat an be accurate to a .10 gram for about $40 or for your size boat a pocket scale I use in my shop would work perfectly about $20 Just saying what your saying "every gram counts"

-Wayne

headhunter23

Good point but living in Canada eh, we don't get the deals your used to, eh!?. Brokerage fees are min 5 bucks and start going up through usps. Where as if you use ups it would cost 35+ for brokerage fees for the same service. It's retarded. Anyways that limits me or the smart canadian to purchase in canada, or somewhere not from the states for a lot of products on ebay, depending on the item etc.

I really need to get a us postal box in buffalo. Would be worth it sometimes. Anyways bought my scale for 20 bucks and it was only 1 of 2 in canada at the time, electric. Was surprised nothing from china, guess its not a hot item.

Anyways scale was really meant for measuring meat for jerky and sausage (yet another hobby a couple times a year, last years sausage batch was too hot) but was fortunate enough to find one that could measure close enough to 1gram. But theres still a way to make that accuracy to 1 gram by merely adding or subtracting a 1 g weight to whatever is being weighed.

Ivan.

ernest2

i have had success running almost hte same motor as yours (walkera 180 i guess) with a 30 amp esc and 8 cells 1400 2/3a batts. runs good on my pt-15 scale boat - 18" long-. yours should be a rocket with those lipos. one note on watercooling the motor, its more effective if you actually make a watercooling that lets the water touch the can, i use two plastic (coke) bottle caps on mine, and its cold as ice[8D]

headhunter23

Actually had been thinking about the cooling alot, because even at 10 amp draw, which it could very well be, it's enough to require cooling of some type. I had read that anything under 8amps doesn't require cooling, could be wrong on that. Anyways if you look closely at the purple motor some ways back in the thread, look at the top where the airplane prop would go, I think I can just stick some plastic fins right on the cap and that would produce enuff wind to cool the windings. Could be wrong but for the 15 bucks the motor was, I couldn't care that much. The burst rate is 15 amps for the motor.

Ivan.

headhunter23

Had finished the boat and ran it a couple times. Fact is I'm not happy with the performance. I think it still needs to be lighter. If anyone chose to try and make this project a success, I would highly suggest all the mods I did in the last tear down but install a motor with 8-10 amps, very light, go outrunner as I do not believe it gets hot enuff to require too much cooling, ensure the motor has dual shaft (shaft on each side) so that if it does require cooling, then you can add a little fan to the one side which would cool the motor. I would highly suggest the motor be 3500rpm/v or right near it. Also intend on going a single 2s lipo instead of two as I did.

I believe that if I simply changed my motor and went with single lipo (same I was using 2s 2000mah)l this project would in fact be a success, but, cost wise and time wise and size for river running (the 12.5 is just a touch too small for river racing), I would highly suggest the cheap nqd or ndq whatever it is jet drive boat that is sold on ebay now. It costs 53 bucks to your door, size wise seems to be great for streams(seems to be jet sprint copy) and comes with drive already installed, it actually comes with everything but I would throw the hardware away. More info can be found on this boat if you check the unofficial jet drive thread, pages 10-12. In fact they seem to have made a few improvements over the graupner mini jet, as of yet it is untested with high speed motor, intend on remedying that tomorrow.

Anyways hope this thread was still informative and helpful for those hacking and trying to make improvements.

Ivan

ctonez

what about a single 3s? would be lighter weight, but still turn decent rpms...

headhunter23

Yea could do that... wouldn't take much and already have the lipos, as they were the originals. Ahhhh maybe... will think about it. Good idea.

mytc3fasterthanurs

to fix ur servo try having on the radio when ur putting the servo or doing any hting to the steering
thats always works for
the reson this works is because the radio and servo will center it self when its on

headhunter23

yea centering it wasn't a problem, for some reason the servo was not going full swing one way. Originally I had broken one tooth, managed to fix that by rotating it out of service area, also ground had come off, so soldered that back on. Not sure what the new problem would be, could be due to water, if a drip or something go on it.

Ivan.[:@]

Quicksilver1

Sounds like you need a new servo. At first I said why doesnt he just change the thing, but I didnt see you have a special micro servo....that sux. I use standard servos, I have like 8 of them, so I never really have to worry. I actually havent broken one yet, perhaps you should just use a regular one, I know theyre heavier and bigger, but theyre powerful, reliable and cheap.

BTW I never said so, but nice job with the aluminum, looks good, I tend to forget you have this thread. I guess your rock problem is a side effect, I've got the same problem, the only remedy is more speed

DRAGONFIRE81M

i like the micro servos pluse my lhs keeps them in stock for the mini-t and i have never brock one on a car or boat i use the hitech 55 there like $15 and i can put thrm just about any where . and haven had a problem with water ether trust me i have had the one in the mini v under

headhunter23

Personally I think I just got a bad one originally, had bought two so was no worries. I like them, 2.7g or around there, far better than the 22g jr servos i have. You could be right about the speed, but I kinda think it's a combo of things, size wise it might really be too small for certain rapids, never did try to put some sort of plastic or something on the runners, could solve problem too.

Am more concerned with the other 2 boats, once those are done and solid will come back to this one and see what I can do.

Ivan.

ryan_t888

Which servo do you use that weighs 2.7g? The ones I use in my planes are S3114 HT 21 oz-in @ 7.8g. These are fairly small but I have seen smaller.

Ryan

headhunter23

They are the lightest ones from UH. More than strong enough for the application.

Traxxas4fun

My Feedback: (3)

are jet drive boats hard to make? could i make one out of a mini v?
how much would one cost that goes 20mph or so?

headhunter23

a couple guys have done mini-v conversion. Dragon... and ummm.. ask in unofficial jet drive forum... the other guy put in a 29mm drive in the boat. Looks good with both mini and other. Not the best hull for jet drive, needs tweaking to work although I think the 29mm jet drive was so heavy with motor etc that it didn't require any further mods.

Ivan.