ok this is what ive got

[Tofastformellow]

Gday ,

i have some left over gear , and some borrowed gear (other projects)

12 cells , 22 or 44 v 20c lipos

cc hv 85 speedy ?? or a cheap ebay 80 amp no name speedy

5mm collet to 3/16 shaft ... strut , rudder

21 rigger

with a 600 bl in it and the batterys etc , it comes out at 2.2 kg rtr in parts

how do i make the best of what i have got .. its a good stramlined rigger , narrow but right height tub ..

want to spin V9 props depending on Kv chosen ive got , 37 or 45 or 55 or 62mm

were do i look for a real grunty 44 v motor ,??

ive got this align 600 thing here , just lying around its 300 grams with mount , @ 1600 kv and for 130 $ AU ill take the risk of burning it .

-it should kick the boats backside for at least few seconds i hope on 44v.

i want to know when it blows , where is the best value in motor to go for this app

motor size anything up to 300-360 grams

been wanting to put together a brushless rigger for years the price is finally coming down enough to maybe risk trying this go fast gear .,.

$ 100 , 80/100 a BL speedys are worth a punt

would 22 v give me the results i want or should i setup the 44v to make the whole exersize worth doing , if it cant keep up with a 21 rigger then i wont waste my time

possible blowing up 600$$$ brand name speedys would suck ... but they are water proof now , some of them ..

on a side note

where do i go to find a good solution to keep the 3/16 shaft from taking in water , were can i get a good gland packing arrangement to keep the motor bay dry ??

some guys i have seen use silicon hose , and heatshrink ??

is this still what gets done , any pics ??

Thanks guys

Jason

 

[Jim Caldwell]

running v937 I would start with 12 Nimh cells or 4s lipo's

6s would be almost a SAW setup on the v937 (22v) high amps!!

I run 1950 RPM per volt underload with a x438 in a 30" rigger at 85 amps with 120 amps at take off on 18 nimh = 35,000 rpm (Eagletreesystems.com datalogger.

Do you want to run SAW or Oval?

 

[Tofastformellow]

running v937 I would start with 12 Nimh cells or 4s lipo's

6s would be almost a SAW setup on the v937 (22v) high amps!!

I run 1950 RPM per volt underload with a x438 in a 30" rigger at 85 amps with 120 amps at take off on 18 nimh = 35,000 rpm (Eagletreesystems.com datalogger.

Do you want to run SAW or Oval?

6s on the v937 !!! that would be good .

sounds pretty close ..

, my main aim is to have something for serious fun,

most brushless riggers i have seen so far have been a little ahhh,

disappointing ,

so im asking the questions first ..

building last.

if i could set it up to do both with a prop change that would be ideal.

i would like to race nitro riggers (21's) and be equal

my riggers tub is 30 inches long ..,

Thanks for that DATA !!!!!

i have a few pics of what im upto if curious

how heavy was that boat rtr ?? that the data was collected off .. ??

120 amps on the launch is a lot , what speedy are you using with that ??

6s would draw less amps ?? not more ??

and 12 s would draw less again...

18 'c' cells weights 900 grams

6s 2200ma lipos weigh 380 grams

so im saving 500 grams there strait up.. that would lower the amps total , as well .

the lipos im useing are rated to 98 amps continuous, 147 amp sustained , and 245 amp burst ,,

i think i got the grunt battery wise .

now i just have to make the rest survive together

Jason

 

[Jim Caldwell]

As you up the voltage the Amps go UP, so you must go WAY down in prop size.

An example would be 442 on 12 cells, 438 on 18 cells with same boat and motor combo.

Lipos will give you about 10% more voltage under load, so smaller prop still.

My controller is Schultz wo105 (18 cells, 105 amps) right on the edge.

Look in Races and results under NAMBA Westcoast time trials for more info and videos.

 

[Tofastformellow]

Im begining to see how this is a balancing act , problem is the usefull props i have are all around 44- 47 mm.. and 3 1/16

im planning to use an outrunner to go for torque ..

but im thinking of around 900 Kv max now after your reply and data.

6s lipos i have on hand , the speedys ive looked at all like to max out at 6s, except the CC HV, but it aint waterproof..$$$

thinking of trying a watercooled CC barra 120 a , and maybe a z power df 900 kv motor and starting at a x440 and work up slowly ...

thanks for your data , how many MA did you consume on those listed runs ??

i see to get the best results you need a purpose built boat , im just trying a brushless repower..

west coast time trials : did some google searching and only found promo's and entry forms... do you have a link ...

Thanks

 

[Jim Caldwell]

The .21 rigger should be just fine, mine is also 30". just get it water tight!!!

3.5 volts loaded per cell X 6 = 21volts. you need about 25,000 prop RPM, just remember the 30,000 rpm limit for outrunners vs 60,000 for inrunners but it will probally pull the v937.

2800 mah for 5 laps on a 1/8 mile course or 1:10 total run time including start.

 

[Tofastformellow]

Hey Jim ,, Thanks for the enlightening Chat...!

the ma you are drawing sounds within the bounds of the lipos capacity i have. ie 70% of 4400 ma , give me some breathing space , i may have to get some smaller props if the KV is going to get to hard to get perfect ...

will sniffaround for just the right KV motor...

your motor is 1950 KV..

and the one i have on hand is 1620 Kv .

that may allow me to get up to the dia i want to run in (where all my props i have are) ....

to balance out the equasion ... cheers dude ...

ive left the top deck off till ive got it all mounted up ... then ill make a screw down plexi lid for it ..

Happy .

Jase

 

[jayt]

Do not use a screw-down hatch, it will leak and will take too much time to remove if you have hot components inside. Taped-down hatches are the best for competition - watertight and strong enough to withstand a 100 mph crash. Screws are so mid-20th century tech.

.

 

[Tofastformellow]

Yeah , but that 3m tape is expensive !!!!

like 20 au a roll...!!!

just kidding ...

Jason

 

[Jim Caldwell]

THATS 1950 RPM under AN 85 AMP LOAD!! the motor you suggest should work fine, abt. 1400 rpm under the same load and will allow bigger props.

Jay is right on as usual, screws will rip out of the hull in a flip where tape spreads the load out and will allow some flex (Impact) with out coming loose.

Hockey stick tape also works good. :lol:

 

[Andrewg]

Too fast the Trex 600 motor is ok if you prop it down to say X640 to stay within the pack limits (confirmed on a data logger) On larger props the amps rise quickly

The motor is not especially efficient at these amp level or rpm but it should push the rigger past 50 or 55mph on the stock 6S

If you run a standard 5 lap heat race it shouls all be fine X642 may be possible - just dont count on things lasting.

You can use the stock align esc if you water cool it very well and stick to the X640. other wise a Castle Barracuda 125 is just the ticket

 

[Jim Caldwell]

one more data point, 63 MPH (gps) on my motor with 438 at 35,000 rpm (18 cells)in a rigger.

 

[Tofastformellow]

one more data point, 63 MPH (gps) on my motor with 438 at 35,000 rpm (18 cells)in a rigger.

Thanks JIm

quote "- just dont count on things lasting. "

ok, whats going to die first ??? on 6 s.. i will probably geta 120 a barracuda...

Jase

 

[Tim_Duggan]

one more data point, 63 MPH (gps) on my motor with 438 at 35,000 rpm (18 cells)in a rigger.

Jim,

Would you mind telling what the RTR weight of this boat comes out at?

Thanks,

Tim.

 

[Jim Caldwell]

Never weighed it compete.

bare I belive it was 18 oz. 6 years ago, probably more like 20 oz now. CF added.