MiniMental

Hi all, i'm back again, i've not had chance to come on for a year or so, had other things to take care of, i.e. my 6month old son and my job (navy), Anyhow, i am embarking on a new nitro boat project. I plan to make a small/med powerboat propeled via a nitro car engine and a homemade waterjet assembly.

I have sourced most of the parts for the waterjet, Billet Aluminium, Seald Ball Bearings.etc but i now need an impeller of around 20mm diameter and have no idea where to look... Can anyone help me?
i have made a rough plan as far as building the aterjet unit goes and, if built, would plan to use this config:-

Heres my PROVISIONAL design idea


24-28" Hull
.18 RC Car engine (from one of my buggies)
1/8" (9.57mm) Stainless drive shaft (to drive impeller)
Futaba Megatech 2PL Radio systems with Futaba S3003 servos

Regards
MiniMental
P.S. Shoutout to Ron Olson, EJP, EAS_1990, TerboBOB, Macelod, Mr Chilly + the rest

MiniMental

I have found bearings, i will use HPI Sealed ball bearings from the savage, their dimensions are (ID: 4/5mm)(OD: 13mm)(W: 5/3mm) I will use a 4/5mm Stainless shaft and machine it to fit an impeller.etc

MiniMental

Since i cannot find an impeller anywhere, do y'all reckon a 3-Blade octura would work as one (i.e. Octura V935/3.etc).... Impeller has really stumped me, would a simple 3 bladed prop have near enough the same effect??

DRAGONFIRE81M

from my experise with electric jet drives youll need a larger motor to turn a 35mm 3 blade . . im useing a .26 ofna force motor with a water cooled head in a 31" with a 29mm grupner drive unit . im working on make a clutch setup for it . so hopfuly in the next month ill have something going . you can get replacement impellers for the grumpner drive and the kmb drives . or you can take a larger prop and cut it down this will put a larger surface area on the tips of the prop edges and make it a sealed system and force the water beter. you can hope on over to the electric speed forums and look at the jet drive thread . nitro is wilcome on that forum . just as long has it has a jet drive in it

MiniMental

I can get a larger motor.. but if i put this unit in a 32" hull, bearing in mind it will be composed of aluminium not plastic, (weight), do you think it would work.... my design - being quite simple- does not have the most 'easy' Flow passage so to speak... to put it another way, it will be VERY heavy duty... the outside diameter of the impeller casing will be 50mm... You think this would suit a much bigger engine and a bigger hull or just a bigger engine?

DRAGONFIRE81M

ok your first thought on the 24" would work better with a 19mm like the mini jet from grumpner . and would work better with a .18 motor . just wondering what kinda motor are you going to use and what are the rpm and hp outputs if you know them. just to help give you a comparason on power need the mini jet which is a 19mm need a 550 -600 motor and the 29mm is a 700 size . eaven though the mini jet is plastic it is pretty hevay i also have found a bearing to make it better . and you can cut down a brass prop to fit . and it would be a lot lighter then an alum one .

MiniMental

UPDATE* I have decided to go with a 28mm impeller from KMB.. i will buy any engine i would need to power my system.. any ideas on cheap hulls with stringers and decks already installed/included??? the 28mm KMB impeller comes with bearings aswell and a drive shaft.... sounds promising..all for £30..

DRAGONFIRE81M

thats pretty close to what im doing and im useing a ofna force .26 big block . and a nova rossie water jacket you can find the head on ebay pretty cheap and all you need to do is sand the inside hole where the glow plug goes to fit tite .

MiniMental

UPDATE 2* I was wondering, would a big car engine work... i was thinkin either a .25, a .41 or a .46.. what you rekon... i know the carb would face the rear of the boat but thats not a problem as i will be introducing a RAM air system....what ya rekon?

[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXHTA2&P=7]Ofna Force .26[/link]
[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXFRD2&P=7]Savage .25[/link]




I also need a few hull recomendations preferably with stringers installed.. i was thinking of these:

[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXRXZ1&P=0]Aqua Craft Hull[/link]
[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXSXH0&P=0]CEN Racing Aquajet Hull[/link]
[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXGBJ9&P=0]Traxxas Villain EX Hull[/link]

Any other suggestions are welcome and would be apprectiated... i like the shape of the villain hull, but it looks heavy and plastic is harder to work with than fiberglass....

MiniMental

I think i have decided on a hull.... I think i may go for a [link=http://novarossi.us/component/page,shop.product_details/flypage,shop.flypage/product_id,8/category_id,5/manufacturer_id,2/option,com_virtuemart/Itemid,75/]speedmaster .21[/link] hull.. i like the drop in the deck at the front of the hatch, this would be good for an aircooled engine... Do you think this hull would work okay with a .26 OFNA Force engine and an aluminium 28mm HydroJet drive unit???

Macleod

Welcome back MiniMental,

Missed your 'thinking outside of the box' projects. [:-]

Im watching.........

MiniMental

hehe hey Ross old buddy, yeah, this ones on its way now, i could never finish my old projects due to lack of funds, but now im working thats not a problem . What you think of my idea and my hull? hope everything has been ok since the incident with your bike.....:|

Macleod

Looks good mate, interesting to see how it all goes, glad you got a job now....??????
Ill be in london in about a month, send me a PM and I talk further......

Got the Wild Thing on the go again and Got a gasser mono finished and running. Will send you the link for the vids.

Talk later......

MiniMental

In summary i plan to build a boat consisting of:

.26 OFNA Force engine
Custom Made 28mm Hydrojet Drive
Speedmaster .21 Hull (maybe)

DRAGONFIRE81M

well the .26 force motor is built off of a .21 block so not a problem there and it doesnt have to be air cooled eather just put a water pickup after the stater and that motor will stay ice cooled . even at idale speed if your going strat drive ill try and find that water jack i have on my force motor

here it is this is the same one i have http://cgi.ebay.com/Aluminium-water-...2em118Q2el1247

and by the way i really like that hull to

MiniMental

Yeah that looks good, but unfortunatley i now cant build my jet drive until after christmas...oh well. please read thtough my other thread Project 2 BACKUP PLAN and leave a comment based on what you think... hehe

I like the hul to, expensive.. but worth it i reckon

Regards
MiniMental