I want 10minutes and 50mph, what will it take?

[supafastsupra2]

I've been on the boards for a while, had a MM on 4s for a bit and then went on a hiatus on the boat aspect of the hobby for quite a while. There's been quite a few nice affordable hulls on the market recently and I think it's time for a new project build. Anyways, My goal is to have a boat that will run for 10minutes straight and reach a modest 50mph. Ideally around 40" hull either a cat or a mono. What kinda of setup would give me the kind of runtime I'm looking for at the speed I'm looking to get? Thanks in advance,

Daniel

[sailr]

In my opinion, you'll need more batteries in parallel than the boat can hold to get ten minutes at 50mph!

[supafastsupra2]

Are there no low amperage setups that could achieve this such as with a large outrunner or something along those lines?

[sailr]

Probably not for that speed but I could be wrong.

[Fluid]

You might get close with a 12S2P setup in a lightweight mono with lots of lift. Outrunners are not magic, what you need is high efficiency at the amp draw you require. High quality carefully chosen in- or out-runners are what is needed.

Assuming you have 12,000 mAh total (2P with 6000 mAh cells), to get ten minutes you need to pull an average of around 60 amps (this gives 2000 mAh in reserve to protect your cells). With 12S that's 2700 watts, probably not quite enough to reach 50 mph in a large boat. I say "probably" because I'm not familiar with anyone who has done it with a reliable setup. Maybe it can be done.....

Run time is entirely dependent on the average amp draw. This means if you can keep the model on step and avoid sharp turns and lots of acceleration, the average draw will be lower than starting and stopping and tight turns. All the energy in the model is in the cells and the faster you "drain the tank" the shorter the run time will be.

What is not often considered is heat buildup. Even an average of 60 amps/2700 watts can cause heat buildup over ten minutes, and some components may overheat. With current technology ten minutes and 50 mph is probably doable with enough work, but not easy. In a few more years with better cell technology it will become commonplace.



.

[j.m.]

Watercolling of the batts may be necessary...

A big cat would be best with a single motor and batts in the sponsons/ beside the motor in the middle. Four 6s 6000mah+ packs would be somewhat affordable, I guess.

A big Neu and a very efficient setup would be best.

Jon

[Make-a-Wake]

A Neu 1527 1.5Y would be a candidate for a low amp draw, super efficient motor on 10-12s.

[DesignerDan]

Do you mean 10min at 50mph or 10min with bursts of 50mph? There's a big difference. My airboat can go about 12min and reach 50mph on the staight ways. Is that close enough? But that's no where near 50mph continously for the 12min. This video shows a little less than half of the total run time and I only got to 40mph once in the video, but she can go a lot faster. It's only 25" so that may be to small for your liking. It uses a six cell 3600mah battery and draws about 40 amps at 40mph and 60 amps to take it up to 50mph. I think no matter what you will need really high voltage and low kv outrunner.

http://www.youtube.com/watch?v=rOdj54Z6Jc0

[graill]

More mah. More capacity equals more time simply put( boat speed thrashing aside). This is of course after you have a sound setup in your rig. (and your rig can handle the extra weight of packs)

I ran the princess many, many times (95") at 54/62 ish, which was max speed on soft timing for 12 min depending on water conditions, it barely got on plane at that speed and timing. One side or the other would always cut out from my voltage cutoffs but thats to be expected for endurance runs. With 12s6p (58) my 18 minute run cooked 3 packs on one side (170 deg, cutoffs disabled) but it was something i was going for in duration and achieved it.