Twin Drive Jolly in the near future.....

[SJFE]

I will pm you a link. There are diffrent weaves. :)

[Flying Scotsman]

Thanks,

Douggie

[G Doggett]

[QUOTE=Steven Vaccaro;15917]Graham thats outstanding work!!! That should scream! What props will you start with?

Hi Steven

I have a r/h and l/h pair of Graupner K40 and 45 to try for starters but hope to eventually end up with metal props.

Also planned for the future are lipos but a) I cant afford them and b) I'm not brave enough yet, so the boat will have to cope with the weight of 24 Nmh cells for now.

Haven't decided on a colour scheme yet but will probably keep it simple like Callan Marine, white with blue lettering.
I'm sure you know the first Callan twin turbine cat was the old Jolly Motor.

Regards
Graham.

[SJFE]

I was going to do the callan marine boat with my jolly also. I decided to fly the OSE colors instead.

[robby76]

SJFE very nice cat. could you possibly post a picture of the underside?

[SJFE]

Thanks Rob. No but tomorrow while I'm at the lake I'll snap one.

[robby76]

[QUOTE=G Doggett;15996]

Graham thats outstanding work!!! That should scream! What props will you start with?

Hi Steven

I have a r/h and l/h pair of Graupner K40 and 45 to try for starters but hope to eventually end up with metal props.

Also planned for the future are lipos but a) I cant afford them and b) I'm not brave enough yet, so the boat will have to cope with the weight of 24 Nmh cells for now.

Haven't decided on a colour scheme yet but will probably keep it simple like Callan Marine, white with blue lettering.
I'm sure you know the first Callan twin turbine cat was the old Jolly Motor.

Regards
Graham.

ABCprops has a 39mm 3 bladed prop L&R. #1516, dia 1.56, pitch 1.6 nom pitch in2.498 , dia mm 39.624, dia mm casting 38.847, nom pitch mm63.398, bore .187, $29.95.
i have 4 different pairs that i use. my best speed has been w/octuras X447 on a 1:2-1 ratio transmission. with the new KB motors out now, there is no need for transmissions - my opinion.

[robby76]

Thanks Rob. No but tomorrow while I'm at the lake I'll snap one.

did you make it out to the lake?

[SJFE]

Yeah all the way out there to realize I had on stupid setting off on the hydra. Waist of my time. I will stick to the hex. PnP 50 bucks toss it when it blows..and I havent lost one yet.

[G Doggett]

Did some testing today of my twin Jolly and even with 33% centre of gravity the porpoising and bouncing is real bad until she gets up to near full speed when she flattens out.
To move the c/g further forward will mean putting the batteries ( all 24 of them) up under the deck.
I am watching with interest how the Toysport version goes and how they solve this problem.
My surface drives are in the same relative position as the picture posted by Steven of the Toysport version, and am also running counter rotation with the props spinning inwards same as the picture.
I can angle my drives down about 1 degree if necessary but I cant see that small adjustment solving the violent porpoising.
I have built and raced several cats and none have needed the c/g to be further forward than 33%.
I'm scratching my head over this one !
Graham.

[G Doggett]

Changed the props to rotating outwards as suggested - no better.
Still porpoises like crazy. I even tried it with two cans of Coke jammed up in the sponsons to give a c/g of about 40% - just the same.
It was exciting opening the cans afterwards !
I think the next move is to angle the drives down to the max ( about 2 degrees ) and try some lifting props to lift the stern.
Still watching with interest to see how Toysport set up their twin version.
Graham.