Baby sv43 twin build

[Jesse J]

Assuming you are serious, Alfa.. and not looking for an argument..
I have seen no reports on this gear box in action.
Only the design specs posted here on Ose store.
I will be testing it on 31k rpms; 780 kv motor, 10s... should be within the specs of hp.
47mm props shouldn’t induce a ton of load..

[Peter A]

Would you be safer to start with testing on 8s?

[Jesse J]

Would you be safer to start with testing on 8s?

Most definitely.. but I need a second pair of the 4s packs I have... no rush, still ice water here!

[Jesse J]

Updates

Motor mount glued, flex shafts greased, water cooling installed, and the most painful part.. steps sharpened.

[fweasel]

Loos pretty amazing. Wish mine was that far along. Hope to see video of your running soon.

[Jesse J]

Hey Ryan, how about some inspiration? watch this!

[Jesse J]

data logging from maiden run

I ended up going with 10S on maiden.. forgot about starting with 8S
I was pleasantly surprised with very low amp draw (likely due to small props)
but the gearbox did heat up to 160deg the last time I checked it (after the 2nd of three runs)

pic one - run 1a: the first time she hits water ( you can see I'm not pushing too hard) and this was not in the video.
pic 2/3 - run 1b: second run out (beginning of the video)
pic 4/5 - run 1c: third time out ending with epic wipe out. you can see the last bump on the graph is the much relieving return to shore.
Turns out the wipe out was due to the starboard strut coming loose.

ripple maxes out at about 2 volts (out of ~40 V operating voltage) and current at about 140 amps
run1a_AH-Ripple_Temp_RPM.jpg
run1b_AH-Ripple_Temp_RPM.jpg
run1b_Ripple-current_RPM.jpg
run1c_AH-Ripple_Temp_RPM.jpg
run1c_Ripple-current_RPM.jpg

[fweasel]

Holy water pick-up! Or is it a depth finder?

I'm closer to selling off my entire collection than I am to finishing my wall of half built projects unfortunately. Yours is running great and that custom mounting rail turned out really nice.

[Fluid]

Jesse, is the gearbox designed to be filled with oil or grease? That would reduce the friction and probably reduce the temps, but I’m not very familiar with that particular gearbox. From the product description that may not be a water cooling fitting.....

Due to the rear overhang, is any roostertail hitting the hull? At high speed a roostertail has a lot of force and could lift the transom. Or not, I’m just spitballing here.


.

[Jesse J]

Jay, the gearbox came assembled and felt like it had grease in it.
As far as over hang, see photos; is that a lot? I don?t imagine the roost would be hitting much of the overhang..
I wonder what the nipple is for? I thought it was for water cooling, but when I tested it, the water came out around the output shafts?!? so any oil/grease you put in there could/would come out into the boat..

One possibility for the wet running, which seems to worsen with speed, is that not all my steps are perfectly flat and/or sharp.. I will revisit them.

update:
turns out many are not flat and actually slope up a little. looks like I need to call on James Bondo...

[Fluid]

Jesse, it looks to me like the fitting is for oiling, not water cooling. With no outlet it can?t be for water. Gear oil may be thick enough to not weep out the shafts. You might want to open up the box and have a look. Water is a poor gear lube.

76F0815D-BB9C-4BE9-B877-35C1060B8219.jpg

[fweasel]

Jesse, where has your CoG ended up? I still haven't decided on battery and ESC location in my hull yet. I'd like to get the battery's side by side on the keel, directly in from of the motor, but not sure I'll be able to pull off the right balance.

[Jesse J]

Hey Ryan, glad to hear your gears working on your build! You had me worried with your last post!
So the video is at about 31%. I ran it again yesterday with about 28% and it was not dramatically better. I’m suspecting imperfect steps.

Is the bottom of yours painted? Have you checked the steps for flatness? Are all the edges sharp on steps and strakes?

Do it to it bro!

[fweasel]

No paint. I have not checked for flatness, step edges are pretty round across the entire hull.

[Alfa Spirit]

The gearbox eats many power, very bad idea.