Baby sv43 twin build

[Jesse J]

Started with paint this time.. then have an idea to go one motor and twin screw, via gear box. Should have 3/16? collets back soon and can start working the 5* slant transom. Made most graphics m?seff.

Now working on motor/gear box rails .. here is mock up.

[Jesse J]

Here is my home design of a motor, esc and gear box mount.
When I?m totally happy with functionality, I?ll have it cut out of cf.

[Jesse J]

Here it is inside and ready for stuffing tubes.
Mounted rudder and mocking up the drives. Still have trim tabs to mock up, but this is where she sits now.

[1coopgt]

Learning time for me. Why wouldn't you move the motor back and the gearbox forward and attach the motor directly to to the gearbox? That 2 inches of flex shaft looks really sketchy to me. Are the couplers square drives so that the flex shaft floats between the motor and gearbox? Also I would worry about the flex shaft coming undone or trying to knot it's self up because there's no support tube around it.

Like I said just trying to learn. Looks cool.

[Jesse J]

Good points Paul; I’m totally open to this kind of input!
So, my thinking is this: goal #1 is to keep cog as low as possible. Funny you say connect the motor directly to the gear box..I asked myself the same question 1 hour ago!
The gearbox needing 8* of down to the back would put the motor a couple inches higher.. making this a self flipping hull?
You are the second of two people to have worried about that 1.75” of open cable... maybe I should be concerned too.
Thanks for your comments!

[1coopgt]

Good points Paul; I’m totally open to this kind of input!
So, my thinking is this: goal #1 is to keep cog as low as possible. Funny you say connect the motor directly to the gear box..I asked myself the same question 1 hour ago!
The gearbox needing 8* of down to the back would put the motor a couple inches higher.. making this a self flipping hull?
You are the second of two people to have worried about that 1.75” of open cable... maybe I should be concerned too.
Thanks for your comments!

I don't think you would need the 8* down angle with the gear box. Level the gear box out and you can do that with the 2 stuffing tubes connecting to the gear box by putting gentle s bends in the stuffing tubes plus if you move the gear box back it wouldn't be as drastic. The one thing to consider is the CG.

[Jesse J]

Thanks for the idea Coop; now’s the time to change.. I’ll mock that up and see how it looks.
I’m not a fan of S bends.. but I’ll see how severe they need to be. I would need to do some amount of S to get the props closer together than the 3in width of the gear box out put shafts.

[fweasel]

I have no actual data to back it up, but I would not trust that open section of flex cable between the motor and gearbox and would not settle on that design during my own mock-up. I agree, lower is better on CoG, but reliability is pretty high on the list too.

[Jesse J]

Howdy,
So upon stern recommendations.. I revamped the design and now have a straight shaft and a servo mount!

A few minor tweaks and then carbon fiber final!

[1coopgt]

Howdy,
So upon stern recommendations.. I revamped the design and now have a straight shaft and a servo mount!

A few minor tweaks and then carbon fiber final!

Stern... ROFL. Nice work . I'm going to assume you want to use the drive shaft between the gear drive collet and the motor collet is because either the collet on the gear drive is to big to clamp onto the motor drive shaft or because you you want the motor where it is for CG? Looks great though. Can't wait to see it out of Carbon fiber.

[Jesse J]

Yes, motor shaft size 8mm, gear box collet 0.25”.. thanks coop for the “nudge”!

[srislash]

Nice rails made there Jesse, these are such nice hulls . Keep up the great work.

PS: have you spun the setup up yet? Very loud?

[Jesse J]

Hi Shawn,
Yes the rails have been a lot of trial, modification recut and repeat. But I think with a few final minor tweaks, they are ready for carbon!
Funny you ask, it did cross my mind to text the system.. I may try it on low power on the bench; I’m curious to hear it as well!

[srislash]

Yes b I am just curious as this setup is what I’m leaning toward on my BBY drag hydro

[Jesse J]

Supposedly there is about a 10% loss in efficiency.. but I don’t have any data.
I’ll fire it up and post video. Beauty of this power train setup is that once the rails are cut from cf, the build will be nearly complete.
If you need a copy of these rails, I know a guy..

[Jesse J]

So I tested it and was pleasantly surprised. The mount rattled a little, but other than that about as noisy as the motor itself.
I’m pretty excited to hear it in action on the water!
If I can figure a way to upload a vid without having to make a YouTube I’ll post here.

[vvviivvv]

im getting away with exposed Flexi

I preferred it than having Flexi to just take any misalignment out and help with vibrations.

albeit lot less strain in my setup.
motors are NEU 1521

[Jesse J]

That’s what I’m talking about! Cheers, Liam, great addition to the thread!
How many runs has this set up had?

[vvviivvv]

it's been through about 4 runs so far and no issues - I know you are spinning a gearbox and 2 props but I think it'd survive. if it doesn't you could always move to bigger Flexi with different collets...

Or one of them little MHZ stuffing tube supports with some stuffing tube... have them in my HPR but it's in the paint shop.

[vvviivvv]

Quick question for you Jesse,

This is the 980mm hull?

I'm considering one, I could even use the power train above on 6s, I know twin 1521 Neu are a little overkill but I'd like to get it well into the 70 mph+ zone

Would probably get another MGM 28026 just for a little bit more ESC power, I have a new one on the shelf ready for a project...

[Jesse J]

Liam, I think you are thinking of the baby raptor, or the baby baby sv43... the baby sv43 in this thread is 48” so I wouldn’t attempt even twin 6s.
The baby raptor works great on 6s. I have a TP 4070 1700kv, 48mm prop in this video.

[vvviivvv]

Yeah, I think "brusher Andy" sold the baby mould to a gentleman by the name of Denis Olivier Mainh?lt

I'm trying to get the smaller one, I think pushing the 48" hull would be close on the NEU's but maybe possible...

I think the hull I actually want is your baby raptor from that video, can you share some pictures of it? does it have a thread? what speed on 6s are you seeing?

think I can squeeze 2 Neu 1521's in? having a slight bend away from the centre line with some custom motor mounts?

[fweasel]

The smallest Outerlimits SV43 is the Baby SV43. It's 48" in total length with a 4" overhang. It's a V-bottom, stepped hull and made by Brusher Andy in Germany, who also builds a 65"(66"?) full sized version.

The RSV Raptor is a non-stepped, v-bottom hull with a total length of 38". The overhang is 2-3" long, I don't have it written down. It was designed by Brusher Andy and the mold was sold to Denis Olivier Mainholt who makes and sells the bare hulls.

[Fluid]

Jesse, has this boat hit the water yet?






.

[Jesse J]

Jay, it has, but the water was confused and it bounced off...
No. We are waiting for global warming to kick in!
Motor mount is completed and I owe you all pics.
It is close; when the thaw happens AND I get her assembled.. watch out!!

[Jesse J]

So after at least five cuts of practice ply, one cut of cf/Kevlar (too fuzzy), one cut of cf glossy on only one side (again fuzzy), and then the final cut cf glossy on both sides....
Power module is Ready for glue!!

[fweasel]

nicely done sir

[1coopgt]

Jesse that's sweet .

[Jesse J]

Thanks guys, it’s been a long road!
I’m really looking forward to maiden run!

[Alfa Spirit]

What is the max RPM with this gearbox?