Fine tuning DF Pirate 35 mono

[Nick1979]

Hello folks,

Here is today's water tests with my newly built Pirate 35. I built the boat with turn fins, but without trim tabs to see how it would handle first. After sone testing it was chine walking quite a bit past half throttle, and as a result I could not reach top speed. Tried different props, etc. Last night I installed trim tabs and went for a water test today. I found that I needed to lower the inner trim tabs to keep it planted on the water. No chine walking that I noticed. CG is set approximately where the "Air intake" is at the top of the hatch. I had to remove the turn fins due to a damaged screw which wasn't holding.
Please let me know what you think - there are plenty of photos of the trim tabs and the way the boat sits in the water. Two videos to watch, too. In the first one, there is a flip over and minor crash, but she landed on her hull so all was fine. Does it look I am on the right track with fine tuning it? Thank you

https://www.youtube.com/watch?v=Uirk...ature=youtu.be

https://www.youtube.com/watch?v=7NB8...ature=youtu.be

Propeller in the first video is Octura X646, and in the second ABC 1817-17-45.

[Nick1979]

There is one more thing I observed - the boat would slow down suddenly and significantly when the batteries (2x3S) go about 3.8V. Is this normal? My cutoff is set at 3.4V.

[Fluid]

It is difficult to see chine walking in the video since it’s so far away - some great shots if your hands though! Seriously, the boat runs well but seems to be pretty loose on smooth water, probably too loose for much chop. Not enough length of the straights to really see its attitude ‘cause it’s so far away. Raising the stinger (not the angle) would probably help, using the tabs alone lifts the transom. Too, right turns only so you can hold some speed in the turns, left turns with no fin slows you down too much.

It is normal for the boat to slow as the pack voltage under load drops, is you LVC set to soft shutdown? Resting voltage after a run means little, the packs may drop to 3.2 volts under load. What packs are you using, capacity and C rating? How many amps do you put back in when you charge them back up? What is their voltage after a charge?


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[Nick1979]

FLuid,
Yes, funny angle as my 7 year old was the shooting the video. No chine walk here on the video - walking was before I installed trim tabs. You are correct - it seemed a bit loose in the first video (she crashed in calm water) but it's significantly better than before trim tabs, as I couldn't even go much past half throttle. Now I can go full speed. I was slowing down on turns because I had to remove the turn fins (now they are back on with new screws). Does the stinger seem installed too low?
The batteries are 3S 5000Mah 50C. I charge them at 1C (5Amps). The ESC could be a soft cut off, not sure how I programmed it. I will shoot some more videos on a bigger pond with long runs and close to the camera. I am really looking for further suggestions on fine tuning her.

[Fluid]

Raising the stinger will allow the hull to settle into the water a bit more, which will help with the chine walking so you can raise the drag tabs. Hard to say how much, probably around 1/4?. Keep the angle the same.

How many mAh do you put back in the cells after a run? If you put in more than 4200-4500 mAh you are running them down pretty far and the LVC should kick in.


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