It's definitely on the hot side, but would work for a 2-lap setup. You could run a very small prop for heat racing but efficiency usually drops off too much with the prop and it will tend to blow the tail in a turn. Some boats will run a great with a small prop buzzing to the moon.
Zippkits jae 21fe v2 outrigger_wood kit build
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First I asked a lot of questions to guys who knew about SAW riggers and then started working my way up from 100 to eventually 148mph. I have probably built around 14 SAW riggers between gas, nitro and electric. Each new boat is some small improvement on the last. When I broke Joerg's 10 year record at 140mph I was only Rev 3 of my own design. Today I am on Rev 9 and only increased from 142 to 148, but it's dead steady on the water and reliable. I have not burnt up a controller, nor cooked a motor, nor waded up a driveline in the current boat. I just have run out of room at Huntsville to run faster. And it also took a lot more than 300A to to get there. I tend to run big boats, but we have run 140mph on a 30" rigger with much less power.
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I got a rare chance (here in the north country this time of year) to test my new electronic setup on the 33. Managed a full pull running the boat on 6s, hit 100 mph with no problem. It's a cold weather run, so I'm very pleased with the result. I should have but did not pre-heat the lipo.
Looks like good data log numbers, pulled 308 amps, ripple current maxed at 2.37 volts. Voltage sag was 19.1 volts (3.18 volts/cell), again with cold lipos. They went in the boat at 57 degrees, was 81 after the run.
This answers a lot of questions for me. And brings up more questions.
How much difference would warm weather/ lipos make? Would less voltage sag due to warmer lipos help with ripple current? Could I therefore run more prop?
Anyway, here's the data log, zoomed in on the 100 mph pass...
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I also posted a video of the run and at the end of the video I went thru the data log numbers best I could. For those who can help me interpret the numbers, maybe watching me go over the data log at the end of the video would be more telling than the screenshot of the data log.
I appreciate you all!
Here's the link to the running video...
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Yes, cold lipos will sag voltage under hard load much worse and ripple will be higher as well considering ripple is just PWM voltage sag. This is because the colder a battery is, the higher its internal resistance goes which turns it into a crappy battery.
You said you went in at 57F which is just fine. Go out there when the packs are 30-40F and pull high currents, and you can damage the pack forever. Those that are purposely pre heating lipo packs for performance reasons will typically heat them to 80-100F as that gets the IR down nicely into low single digits for a good pack, but is not hot enough to cause any damage to the pack.
What do you mean by "better" on 8S? Better in what way? It will go faster of course, but your current values are going to scream upward as well due to more voltage/RPM and load on the model. Current only goes down with higher voltage IF the output remains the same as before. So going from a 6S setup to an 8S setup would require a lower KV motor in order to equal the same RPM output, otherwise the current follows the RPM
I have a 36" mono that pulls 8HP in the data logs on 6S running 75MPH with a 1716 prop. I run it occasionally on 8S with the same setup, and it hits 88 MPH, but the power jumps 50% to nearly 12HP! That's way above the motor rating, even the burst rating, so I keep those runs down to 2 quick passes.Comment
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