just testing the water

[RIGGERMORTISE]

well eventually i supose I had better do one so here it is. I have at my disposal the following.

Jetti advance 70A 3p controller

MEGA motor ACn 22/20/3

which is 6 to 27 cells, 1850 rpm/v, 70A, 27 ohms 3 pole.

very light Tom Moorehouse Blazin .12 rigger in timber carbon composite.

My question is

What can this combo do in a rigger and what size? I am asuming I will run 12 or 18 cells depending on what our rules end up specifying.

so would this push a 1445 on 12 cells and go fast enuff to excite me!!!

or do i need to get a diferent motor and controller!

Thanks

Dave

 

[Kris Flynn]

Dave,

I would love to give you an exact or proper answer, but i can tell you some things....

The controller might be alright, the amp rating is good and the brand is also quality (as far as i know)

the motor sounds like it has the same RPM per volt as an 8XL so a 1445 shouldnt be out of the question on 12 cells.

How long is the tub on the rigger and how wide? also how high?

Kris

 

[PropNut]

Dave,

A 1445 will put you very close, if not over the rated amps for that controller on 12 cells. Try a 1440, that will keep you well under 60 amps and should give a speed in the mid to upper 40's.

All the best,

Ray

 

[jayt]

The motor has insufficient mass (just 6 ounces, a good XL motor weighs over twice as much) to handle 12 cells at 70 amps, and it may not have the torque required for a large prop (the light weight of the rigger will help). Realize that max current is not recommended current. I'd run it on 8 cells and an x637 prop first to see how it handles the heat. You may find that it can handle an x645 on 8 cells - my Sport Hydro runs an 8XL on 8 cells and that prop, giving 40 mph speeds.

 

[Andrewg]

Dave

The Jetti advance 70A 3p controller has similar hardware to the Jeti Hacker controllers but very different software. It isnt water proof so make a small box for it (not in the radio box) its important to keep the wires from motor to esc to pack as short and thick as possible so the ESC box should go between the motor and cells. 12 awg wire is a good thing.

For safety sake use silicon coated wire like Deans and Deans plugs for esc battery; use Schulze 3.5 Perfects or Neu 6mm for the motor esc connects. Dont skimp here i havent seen a nitro boat burn yet but i have seen electrics on fire because of a short caused by melted cheap connectors and modern cells can put out amps to weld with. Stay away from 4mm plugs. There are too many cheap copies about and they are rubbish and get very hot.

The ESC has two timings; start with the low one. Use 12-16mhz operating frequency if it can be varied otherwwise the stock 8khz will do. Part throttle performance isnt as brilliant as the hacker so keep it WOT as they run cooler this way!

MEGA motor ACn 22/20/3 - like Jay says its little - if you set it up with a X438 and 12 cells it will give you maybe 40 mph with a light rigger.

If it doesnt get up it isnt going to - it wont come on the pipe! But if it drags arounsd with the prop submerged the motor will draw big amps. this is yet another way to practice your welding if things go pear shaped. Bring it back and make adjustments.

Good cells have higher voltage under load. There are no hidden gems. Stick to GP and IB 3300 and higher capacity. IB 4200 SHV's give the best test results iI have seen. Zapping improves voltage and therefore rpm. Cycle the cells prior to use, especially if you dont know their history or they are new. This will help get max volts and capacity. Charge at 3.5 amps max and run the cells hot off the charger.

When you are running the pack will "dump" performance will slump sharply - try and bring it in when you notice a bit of a drop you will extend cell life. Do not run the cells past the dump point you stand to destroy them. Bring the boat to the closest shore. Recharge only when the cells are cold.

Amp draw under load is going to be mid-40's on 12 cells. It should be good for about 80-86% efficiency very easy setup as these motors have a torquey characteristic. As a precaution water cool it.

Once you have it setup and running well (time how long it runs so you can work out the current draw) switch the timing to high advance it should hum - just watch heat.

It will be legal in 8-12 cell hydro - there is a rigger class proposed - at this stage it will dominate the class ;-)

 

[RIGGERMORTISE]

Thanks to everyone for their replies!

seems that if i use this setup then i will need to get a deck chair to race with!!!! :blink: Ok so the next thought would be that i want to do 60mph or faster so its time to work back the numbers to get the motor, cells and esc to match the speed i want. <_<

So from what i can gather here, is it would be better with a 8XL, 12+ cells 1445 prop and a good 70+ ESC.

This should get me closer to 50, 55mph????????????

If not then the only economical choice is a NOVA21, SPP, Firefighter, H4 and 60% for some 60+ mph fun. B)

Thanks again

dave

 

[Andrewg]

Dave

you could always drop me an email.....

 

[jayt]

...the only economical choice is a NOVA21, SPP, Firefighter, H4 and 60% for some 60+ mph fun.

Why would you say that? In a 12-cell rigger with a target of 60 mph, you'd be better off with a 6XL (same cost as an 8XL), a 1640, 12-14 good cells and a Barracuda 80 or (preferably) a B125. This will get you to 60 + mph in the right hull with the right setup. B)

.

 

[RIGGERMORTISE]

...the only economical choice is a NOVA21, SPP, Firefighter, H4 and 60% for some 60+ mph fun.

Why would you say that? In a 12-cell rigger with a target of 60 mph, you'd be better off with a 6XL (same cost as an 8XL), a 1640, 12-14 good cells and a Barracuda 80 or (preferably) a B125. This will get you to 60 + mph in the right hull with the right setup. B)

.

I like the sound of that!!!!! now i am very interested. If there are any other details like recomended weight and hull size it would be apreciated.

Thanks

Dave

 

[Tim_Duggan]

In a 12-cell rigger with a target of 60 mph, you'd be better off with a 6XL (same cost as an 8XL), a 1640, 12-14 good cells and a Barracuda 80 or (preferably) a B125. This will get you to 60 + mph in the right hull with the right setup. B)

How many laps of a full size course would this set-up be good for? We don't run the small courses in Oz.

 

[Andrewg]

Tim

probably about 2.5 minutes with decent cells you should need half the time for 5 laps

the 12 cell monos we run here are the same as US setups

Our setups run little faster because the ovals have longer straights and wider turns

By the same token this helps a little with runtime as the motors wind out to more efficient motor speeds

However we use more of the available capacity.

 

[RIGGERMORTISE]

Tim

probably about 2.5 minutes with decent cells

the 12 cell monos we run here are the same as US setups

Our setups run little faster because the ovals have longer straights and wider turns

By the same token this helps a little with runtime as the motors wind out to more efficient motor speeds

However we run our cells to near empty.

cool with 1:17 heat times we can race twice!!! this is starting to sound cool!!! no warm up laps required!!

Thanks andrew

Dave

 

[Andrewg]

Dave

I nearly rang today

I was thinking as you have that gear build the 12 cell with the mega - we are probably being a bit pessimistic

High amp setups can go up in smoke pretty quick and electrics wont give you the warning signs you are used to. A lower amp setup is a good way to get familiar with some of the issues with electrics without burning it up

High current, electronics and marine is still a very difficult environment. In electrics you buy the power package and it will setup to work pretty reliably out of the box. But to relaise that potenial hull design and setup are critical - get that sorted and you can unbolt and replace stuff in a matter of minutes and run long or run fast.

Now we are lucky Jayt is the guy to talk to. Forget the other static Jay has 25 years experience a book or two and a bunch of records under his hat and has designed many race and SAW riggers (when is the winged wonder comming out again Jay?)

In terms of speed he may know one or two things the rest of us dont - Jayt currently holds the IMPBA SAW record for 12 cell rigger at 83 and a bit or in our language 134 kph.

Also the issue of RCBM with the blue and white bat boat on the cover has a great article by Jayt in it on water proofing for electrics.