dylan gregory

Hi
How do you guys think a scaled up version of this hydro will work like.
Good,bad,average?

[img]

Thanks
Dylan

Simon.O.

Dylan,
Scaled up from what to what ?? How big do you want to make it ??
The profile is good for a lower powered hydro running a very old brushed can.
There is massive AoA on the front ride surface and the angled drive shaft will give plenty of lift to the rear.
I have run a shovel hydro with similar characteristics due to lower power available.

It all depends on what you want to do here.
Recreate an old design and run it............I have and do with a lot of fun
Use this as a plan to go really fast.........not really likely

Make a boat and have fun.............now we are talking !!

Give us an idea as to what you want to acheive and I am sure there will be a lot of help on its way.

dylan gregory

At the moment its about 9 inches long and I want to scale it up to about 13 inches. I have a 370 brushed motor and 6 2/3A cells.
I just want an easy boat build thats a bit of fun and semi fast.

Thanks
Dylan

Crabstick

http://microhydros.com/hull_plans.htm

these plans might also interest you

dylan gregory

Yes i have seen these plans but i quit like the look of this one and it
looks like it could be quite an easy build.
What size prop would you recomend for this typ of boat?

Thanks
Dylan

Crabstick

Hey Dylan


13 inches is very small, you would almost definately need to go lipo and brushless to make it "semi fast" and you are going to have issues finding decent small props

16 inch or so you will get away with a 380size bl and lipos and it will handle a light chop... thats the size id be looking at least then if the boat doesnt work out to be a good design, you can swap out your hardware to one of the 1/16 scale Rum runner hydros (free plans somewhere on rum runner site)

dylan gregory

Oh ok
Where do you buy your brushless motors and controllers from in NZ?
What if I make it 16 inches and used a 400 size brushed motor?

Thanks
Dylan

Crabstick

Hey Dylan

I buy from China - www.hobbycity.com

just make sure whatever you order is in stock, and you will be ok, dont order out of stock items as sometimes they take an age.

Buying here would push the costs up a bit more and availability is pretty useless.

dylan gregory

Ok thanks
What do you think about making it 16 inches and using a 400 size brushed motor.
Im not that keen to jump straight into brushless and li-po yet.

Thanks
Dylan

Crabstick

TBH you will be lucky to get 20mph

small brushed motors are highly inefficient and NIMH cells are heavy, Unless you can find a special 400 sized motor like an old kontronic or graupner speed 400 race or something

with BL and Lipo 30mph would be easy - more power and lightweight. Take the leap, you will not regret it

dylan gregory

What type of motor do you recomend and do brushless motors work allright with NIMH because i dont realy understand charging and balencing li-po's. Would i have to you's a stronger propshart and things like that.

Thanks
Dylan

Crabstick

Ok BL works with Nimh, but IMO the weight of them just robs you of free performance

Lipos are made of of 3.7v (nominal) cells, ideally its best to Balance Charge them, most lipos these days have a balancing plug that you simply plug into the charger

Brushless motors generally produce a lot more power to weight than a brushed motor, so you would run the same size driveline, (.150 is what i use) but the motor would be a lot smaller

for a 16 inch boat i would go with something like this : http://www.hobbycity.com/hobbycity/s...hless_Inrunner

Feigao 380 8xl and run it on 2s lipos - roughly equiv to a 7.2v pack in voltage, but not weight

I would run two of these in parallel

http://www.hobbycity.com/hobbycity/s...C_Lipoly_Pack_

and buy this charger, which will charge both packs at once

http://www.hobbycity.com/hobbycity/s...Charge_Capable

i would expect a lazy (not trying too hard) 35mph

Nimh cells in such a small boat is going to rob you of speed.

alloutcustom

I would run 3s lipo on that motor, or choose a L size motor for 2s

Crabstick

if it was mine, I probably would run 3s also, but this would be Dylan's first BL and 2s on will be a good starting point, without being too crazy and allowing for larger props to be run, Here in NZ small props are hard to get hold of

dylan gregory

Ok those look good.
Do you think I should run it on two of those li-po's?
Is that site American?
and how much is the postage?
What size prop would you recomend for a setup like this.

Thanks
Dylan

dylan gregory

What do you think about useing an outrunner and just cooling the motor
mount because its so much easier over here to get outrunners.

Dylan

Crabstick

the site is in china - postage is cheap and fast if you order in stock items.

for a prop i would start with an X432, with shallow strut depth.

You could indeed run an outrunner, but still in nz you will pay 70$ for that outrunner that will cost you 20 $ us at hobbyking.com, same for the lipos, and as for the charger, i saw a local model shop with that 28$ charger for 150$ !

ROFL

add me on msn if you want pm me your hotmail..

dylan gregory

Sorry i dont have msn.
Do you think this setup would work on the Hydromite off microhydros.com?
Could i run it with just one li-po?

Thanks
Dylan