mickieb49

Hi All just thought i'd start a thread wich seems to be missing from the Nitro pages, their in the electrics and Gas pages so why not?
Here is a few pictures of mine that i have built from scratch. Fiberglass hulls, 3.5cc pullstart nitro engines and Graupner GR-2344 Jet units.
Also if you are interested in one PM me.
Any one else who has dabbled in these little boats pitch in, i would be very interested in other peoples builds.

opelckadett

This is al really nice funboat. May i ask where you did get the drawings.I´m interested in one.

mickieb49

Hi Ceck your PM.
I designed the hulls off the real boats,most of the drawings are in my head . They play like the real things but obviously with a few changes were made as the small boats operate a little differently, the ones you see are about MK 5-6 . Changed things like the delta pad is longer, the v is alot less than the originals and the lifting strakes are a little bigger.
Cheers Mick

advanced builder

That hull looks like a fun time. Nice job mickieb49 the only thing I see, your header is rather long , do you get" onpipe"?? no need for props here
How fast does she go ? over the years I have lost 5-7 props to the pond god.

mickieb49

Thanks, I had to make them this long so you can get the can to miss the back of the boat. Because you are on and off the throttle you do get a little "on pipe" but it is not all that noticable, Will experiment with the TIG and see if a much shorter pipe works better.
Suprisingly they go quite well, ok not as fast as a prop drive but somewhere around 40-50 KMs or 20-30MPh ? But you get the added advantage of running them in area's where you can'y get a prop drive. Flooding creeks are the best. I am in process of building a short course sprint track on my dam that i can flood when needed
Yep i have lost numerous props and shafts to the dam gods and probably will do again (not if i can help it )
I can upload some dimensions if anyone wants?

DRAGONFIRE81M

i had came up with a flex drive converson for that drive when i started runniing it on nitro . here is a vid of that drive and a .32 ofna motor in a 32" deep v

http://www.youtube.com/user/dragonfi.../6/styk7GQaX1M

mickieb49

I have had a few questions regarding the drive setups, from the engine to the unit i use a dog'n'bone setup (this has minimat distortion)  and the jet unit is FULLY Glassed in, i mean there is cloth going around and over the jet unit, this prevents what people will say to split the unit under pressure.  The engine is solid mounted in as to eliminate the flex from the engine to the jet unit, there hasn't been any problems i have had  doing this, which i have been for the past 7 years and about 5-6 hull designs.
  If you go on Graupner's website they will state that the GR-2344 unit is not suitable for glow setups, this unit has served me very well with glow engines and is cheap too.
  If anyone else has delved into these sprint boats i would like to hear what they have to say.

DRAGONFIRE81M

the problem i had was i couldnt keep the shaft lubed under the 40k rpm i was turning it at when it was an electric setup . then i went to nitro . i epoxy the drive only around the sime and around the base . and havent had any problems other then the the $ of the drive keeps going up . so i have molds of every part on the drive but the impeller . with i have some custem cut down props a 3 blade and a 4 blade with the same pitch as the stock 2 blade

mickieb49

WOW !  i was going to do the same , using silicone molds and investment casting stainless impellers, this all just seemed to cost alot more that the unit costs from hobby lobby though.   I was selling these boats RTR before, just got sick and tired of trying to please the wingers of the model boat world, there is just no pleasing somepeople ?   so i ambandoned the whole idea of building the jet unit aswell as the hulls,  afterall  there is bugger all profit in them , it was all for the love of the hobby.
  40k eh.....gee that may have been a little much  revs    I always thought that jet unit efficencies  went out the door over about 18-20k  ?
 Torque was always what i chased for.

DRAGONFIRE81M

you cane see for your self .

here is that same hull but running a 2250kv on 22.2v so 49500 r's unloaded http://www.youtube.com/user/dragonfi...17/hJNx468n45E

heres a cen auqa jet hull with a 2900kv on 14.4v 41760r's unloaded with a 3 blade impeller http://www.youtube.com/user/dragonfi.../1/9zZL0HMDj3Y

i added some pic of the flex converson , the .32 big blue and the mold of the stater nozzle

mickieb49

Looking good, do you use silicone molds then inject the molten plastic directly into the mold? or inject wax into them and set the wax blanks into a plaster?
  Your vids look unreal, the brushless setup really screams.

DRAGONFIRE81M

no i use a two part urathaine just pore it in and in about an hour your can demolded and its also tentable . i need to make a vacume chamber to help get the air out thats my next step im also going to make a vacume former so i can make the intakes

how yeah i use a silicone mold

mickieb49

A Poly urathane?  is this the same type of plastic used for injection molded parts?

DRAGONFIRE81M

not really in plastic molded parts are made with small plastic pillets melted in to shade . this is almost like a two part epoxy . its a little to hard for what imuseing it for . if its a thin part it can become britle the longer it sets . im looking for something with some flex but still strong .

mickieb49

What about glass filled nylon ? this stuff is super tuff and durable, a guy i knew used this stuff for making his props and he never sheared one yet .
Other than that what about investment casting and making alloy or brass ones?

DRAGONFIRE81M

i have thoght about it . but i thank ill have to make a new mold to cast alum parts

kawjs550sx

These boats look great! I am very interested in starting a project like this. Do you have plans or drawings of your design? I have a spare 3.5cc engine that I would like to use.