headhunter23

mm... would like to see that. Still don't completely understand how u would add it to the other jet drive though. You mean cut off the back part of the jet where the prop is sitting then splice in the other drive? I think I would prefer just getting the other drive.

DRAGONFIRE81M

its easy to do on the grupner drive just remove the black stater and impeller houseing and insert the gray starter of the 40mm drive not sure about the 28mm kmb drive

Quicksilver

yeah that's what I meant and on the kmb, I was infering it might be possible to cut off the part of the duct where the impeller is housed and grafted on the graupner part, buw yeah buying a new one would be better. I do think the duct from the 29mm graupner would work better for our application. The one that comes with the 40mm is raked out more, which is why it's like 4" longer than the 29mm, the 29mm duct would work better for high speed boats, unlike it's normal application.... Moonraker or some boat like that(large scale)

headhunter23

mm... so ur saying it would produce more speed by grafting than just getting 40mm? Whats minimum size boat a 40mm can fit in (ie 31inchs)? My guess is you could determine the length of the boat by where in inlet is supposed to be positioned? Ie 30% of hull from back?

btw looking at this site,
http://www.cornwallmodelboats.co.uk/...upner_jet.html

there's a 49mm? cool... and only 2.5cm longer than 40mm version.

Graupner Jet Propulsion Unit 5 (2347)

DRAGONFIRE81M

thats the same drives thats in that huge twin drive that smokerete is building btw look at the bottom of that page they sell replacement mini jet impellers

DRAGONFIRE81M

well here is something to look forward to . there it the boat that uses twin grupner 5 jets http://www.youtube.com/watch?v=1cClZ4FYc3E

DRAGONFIRE81M

my bad it uses twin 40mm

headhunter23

No streams for that beast, only rivers!

grael

Took my boat out for a blast with out local Lower Hutt Power model boat club today, Had a kid try to video my boat, but he only took crappy stills... never mind, off to a meeting by the beach shortly !

Hard to judge speed by eye...


Apparently one of the faster cats goes to about 75km/hr,

All I know, is that I ran around the course one time, and that of the cat that was out there when I was running, it overtook me, but slowly I'm happy, most of them are running ASP 60s or ASP 90s now.

So to be going almost as fast on a jet.... with an ASP 40, stoked

Quicksilver

well, I merely am saying that the shorter duct should work better than the one provided with the 40mm, ideally I would really use the graupner 29mm duct. Grafting the KMB would take some careful planning.

There's no reason that couldnt go on the villain. In fact that's what I'm recommending it for. I'm seriously considering buying one, especially after that vid dragon just posted, the atlantic challenger is huge, a villain would seriously haul ***** with a 40. However I wouldn't put that 49mm in the villain[sm=tongue_smile.gif] but than again....muh hahaha!

headhunter23

lets all start a chant, do it, do it do it do it!!

grael

Just come back from a meeting near here:
http://www.rcuvideos.com/video/ASP40...op-cut-down-to
Got only a very short run in before the replacement pin for my dog and ball coupling went again.

Keen now to try a three blade very high pitch metal impeller, the engine still seems to have some spare power available.

Vinnystoolbox

6 seconds before it died that must have been annoying ............ Hope it lasted longer than the video, looking good


Quick ............... Do it, do it, do it ........ LOL


My boat is coming along, but with kids don't have a lot of time for such things, will be around before spring though.

Quicksilver

You know coincidentally after we were talking about the 40mm drive, I was on another forum and saw exactly what I was talking about. I wish I could post it......oh what the heck, I'm sorry to the builder if this annoys you, the point must be made.
here's a 40mm drive in a fast tec. See what I mean about the duct, freakin huge, short duct would be much better. It looks imo ridiculous.

grael

Hi vinnyst,

I got that fixed, but then I jumped the raft at our lagoon a couple of times, and my AAA cells popped out of their holder, with engine on full speed.

Went full speed to end of the lagoon with one bounce off the side in between, crumpled the fibre glass in the front, bow shot up and the stern sank, engine drank some water and stopped.

It starts again fine.... but I need to rebuild the front now.[&o]

grael

I agree, it looks like a dog on that hull.
The suction created from the jet would keep the bow down, the motor/engine is even further forward, so the C of G has to be ballanced by radio gear/batteries,fuel etc right at the stern. If it did go fast, (which I can't see happening), then the front of the intake is way too close to the part of the hull which should be riding in air. From experience, I've found that jets of that size need a really powerful motor to get any speed out of, so their boat will have weight issues as well.

headhunter23

What size was the hull?

grael

It's 750mm long, or for those of you in the USA still using imperial, two of ye olde pommie King's feet end to end, and one peasant's foot of the same length, but chopped in half and added on. (2 foot 6 inches)

Here's the damage, 2.5kg zipping along at about 50km/hr, and straight into the wall of the lagoon:

headhunter23

mmm sorry grael meant for quicksilver, already knew ur size o hull from previous posts. Sucks that it got toated, u were saying u were going to make mold for popping out new ones? u didn't manage to copy hull before near death did ya?

grael

I have the mould already, it's 15 years old now

I'll try a repair first though...[8D]

headhunter23

I could see u repairing the bottom, tis the top that's mashed though...

grael

The top and the bottom are both damaged. I have moulds for both, but my top mould is a bit basic, I don't have anything moulded in for hatch; engine access etc. There's quite a bit of space invader foam in the front, else the damage would have been far worse. I was stunned to see only that amount of damage for the speed it was doing !

DRAGONFIRE81M

hey quick ill give the guy props for a nice and clean in stall . but that drive is may to forward . one he could have trimed the duck down a bit and moved part of the outlet to the outside and made a cover for it . like you see on the sprint boats . that was a high $ build that bear hull is almost $200 then a nother $100 for the drive . craze and i bit it runs like crap in its own wakes . sad story there

j.m.

I tried to tell Diego boy on OSE that the drive was too big, but he had already cut the hole for the intake.

(way too far forward, I might add...)

And he wanted to use a 540l on it!

He didn't understand that he would need at LEAST an XL.

But you can't blame him. Hes a prop guy.

This was his first prop-in-a-tube, and I guess he just needs to learn.

DRAGONFIRE81M

its not his first but it is on that size of drive . his has a ringger with a mini jet its pretty cool looking