32' cat twin powered
 

Hi all
heed Your opinion about motors for my cat that i`m bilding.
The hull from e-bay with some modifieng.
http://forum.modelka.com.ua/uploads/..._206_27926.jpghttp://forum.modelka.com.ua/uploads/..._206_35961.jpghttp://forum.modelka.com.ua/uploads/..._206_10389.jpghttp://forum.modelka.com.ua/uploads/..._206_10893.jpg


Thre batteries 4s Li-po double. Props Octura X442
http://www.hobbycity.com/hobbycity/s...hless_Inrunner
http://www.hobbycity.com/hobbycity/s...hless_Inrunner
to motors with same Kv but different power and weight, L and XL size.
What is Your opinions about this two motors. Will be able L motor run X442 prop in double drive setup?, because XL too heavy for the hull.

RE: 32' cat twin powered
 

One 8XL motor on 4s would make this boat run high 40's

RE: 32' cat twin powered
 

Thank you for reply,
I know it but I want double drive.

RE: 32' cat twin powered
 

well it all depends on how fast you want to go..
twin 6XL is alot on 4s, possibly to much for the hull to stay on the water
I would pick a lower kv motor say around 1800-2000kv if your going 4s, also run times will be longer
also weight will help keep the boat stable, so don't worry much about adding to much weight

RE: 32' cat twin powered
 

Could you show more detail of sponson mod since mine needs it bad. I'm going to try 2- 7L feigao's on 2s1p each ans 42mm -45mm carbon props to start. Might go to a pair of UL-1 motors and 4S1P each side.

RE: 32' cat twin powered
 

I know that the revilution at least 30 000 wil be good for X442.
I want 62 mph for the start,so I modify hull

RE: 32' cat twin powered
 

You can see here thread
http://forum.modelka.com.ua/index.ph...st&p=93091
The dimension in mm.

Tell me please info about your UL-1 motors or may be link.

RE: 32' cat twin powered
 

Aquacraft UL-1 motors or Aquacraft Supervee motors. Maybe not for 60mph...

Thank you for sponson details

RE: 32' cat twin powered
 

How did you cut the wood so nicely? Table saw?

RE: 32' cat twin powered
 

any reason for the exact number, looking to set a record?
If you went twin 8XL or 9XL on 4s you will have all the power you need to get to and over that speed

RE: 32' cat twin powered
 

Its probably because 62 mph is also 100 kilometers per hour, which im assuming they go by in the Ukraine.;)

RE: 32' cat twin powered
 

yes, the saw table needs to make wood wedge. But I havent it. I used vertical metall milling mashine with simple hand-made appliances. Next the wood was boiled in water and bended.

RE: 32' cat twin powered
 

100 km/h it is for the start. So I need a lot of power.
A man from russia make 90 km/h on this stock hull with 4s lipo for each stock motor and K39 graupner carbon prop. But one motor and props die after that. The speed measured with GPS.
I can repeat that speed as well but I need more!
Heres the thread
http://forum.rcdesign.ru/f2/thread14...ml#post1405715

I decide XLmotor. I saw video on u-tube about smaller cat with double 9XL and 6S. 75 mph and good attitude on water.

RE: 32' cat twin powered
 

This is going to be fun! :D

RE: 32' cat twin powered
 

Yep this is the video, I bought one of these hulls after watching this video
http://www.youtube.com/watch?v=XEjJRiPyEyM

I would follow this guys lead, if you want fast then pick a lower kv motor of around 1500kv and go with 6s
you will have lower temps and longer run times

RE: 32' cat twin powered
 

yes, that video.

I had couple of 9xl motors but decide sold them. One of the reason is dimension of batteries. They bigger than sponson gap inside hull. After cutting unnecessary in the hull only 41 mm wide is possible insert in sponson. The 6S batteries is start from 43 mm. The next reason is the money. Doble drive eats double money.
And about Kv 1500. Jast a bit calculation:
6S=22 volts
X442 pitch =42mm*1.4=59mm
revolutions=22*1500=33 000 rev/min
speed=33 000*59=1947 000 mm/min =1947 m/min=117 km/h
taking into account slippage 20% the speed is only 117*0.8=93.6 km/h
This is a maximum theoretical limit.

RE: 32' cat twin powered
 

Will this run as a SAW boat, only making 2-3 passes and then brought in to cool off?

Does it really need to be dual drive? If you went single you could spend good money on quality components that will achieve this speed reliably.

Ryan

RE: 32' cat twin powered
 

Only extra cost (running 6s) would be the batteries, and decent packs can be bought at hobbycity at a cheap price.

RE: 32' cat twin powered
 

I love cats double drived and mono single and not vice versa.
The cat hull is just made for doubledrive. The motors and batteries make CG extremely low. The hull is full symmetrical so no prop rolling no sideways.
I want like SAW, just let to GPS show me 100+

RE: 32' cat twin powered
 

this hull is fairly narrow and could induce some roll with alot of power, also this hull can take a single setup with ease

RE: 32' cat twin powered
 

If it were me I'd set it up with Neu motors on castle ESC's. 6S per motor should be most reasonable. This would also be most reliable as well.

Ryan

RE: 32' cat twin powered
 

I agree :)

RE: 32' cat twin powered
 

take a look at this video: http://www.storacingproducts.com/dra...brushless.html This is a EKOS without esc's, batt's and radio. Video is boat running with non counter metal props, 5S... It's humming and those are 380 motors, 2450KV...

You don't need to break the bank to break 60mph.

RE: 32' cat twin powered
 

I forgot to mention that these Ebay cats are the same as the above link hull and the Venom EKOS. I have the same Ebay white hull and all the gear, just no time to build it...

RE: 32' cat twin powered
 

Than you for video!
As I wrote a man from Russia make 93 km/h at this cat. I think you cant see pictures at my links without registrations.
Some info from there
motor like feigao 380L Kv=2800
double 4s Li-po
props Graupner K39
Speed 93 km/h
Current 82A per motor
Temperature of motor max 60C
Maximum electrical power o n each motor 1200 Watts
As you can see the motors and ESC are overdriven.
Photos from there

http://image2-6.rcuniverse.com/e1/ga.../lg-184223.jpghttp://image2-6.rcuniverse.com/e1/ga.../lg-184225.jpghttp://image2-6.rcuniverse.com/e1/ga.../lg-184226.jpghttp://image2-6.rcuniverse.com/e1/ga.../lg-184227.jpg

His hull from here: http://www.rcm-pelikan.cz/index.php?...t&id=38168