Creating a steerable drive

[srislash]

Hey guys, I’ve always liked the steerable drive unit idea, making it work successfully is another matter. I have a twin pair on a 40” mono and the problem there is that when turning right the drives lay over that way and the right prop digs further into the water as the boats leans over. This creates lift and spins the boat out if you are not careful. Sooo, I got to browsing one day and going thru some parts and realized that MTC drives are a good place to start a new creation. https://www.modellbaucenterlorenz.de....html?___SID=U
These drives have a ball socket where the drive tube meets the mount allowing for full adjustment and swing of up to 30* each way. It is also a good seal to keep water out.
I removed the adjusting arm and got a turnbuckle to take its place( have a ton of car gear around) with ball links



My plan here is to get this drive to act as a pendulum where as it moves left or right it raises to follow the hulls V.

[srislash]

So as it sits in the above pic the drive moves back and forth on a even plane. Not what I’m after. I tried a longer turnbuckle but the same result. It took some thought but I started thinking about camber and such(once again from the car memory banks) and thought what if I moved the pivot point of the turnbuckle forward or rearward it would change the geometry. So I made this rough cut piece of aluminum:



And now I have 5mm lift at 15* throw.

Well that’s where I am at right now. Ingenious suggestions on improvements or theory shall be appreciated.

[RaisedByWolves]

Interesting idea.

Do be aware though that if you change the drive angle of the drive it will also have an effect on how much vertical movement you get in the arc of your throw. You would have to shim the upper pivot in/out to compensate.

Also you may be better off turning your top mounting point 90* for added stability and articulation.

[fweasel]

Sean, thought of your project when I saw a picture of this setup recently on a scale Fountain

FB_IMG_1517938574931.jpg

[srislash]

I have seen that one Ryan and Werner at WD200 has some as well http://www.wd200-modellbau.de/?Antri...kbarer_Antrieb

Interesting idea.

Do be aware though that if you change the drive angle of the drive it will also have an effect on how much vertical movement you get in the arc of your throw. You would have to shim the upper pivot in/out to compensate.

Also you may be better off turning your top mounting point 90* for added stability and articulation.

I haven’t found the articulation to change at this point. The drive angle would not change much(unless I ran ABC props, lol). I am thinking the same on rotating the top pivot 90* and possibly pin it top and bottom instead of a heim joint. I need to figure it how to stabilize the stinger from rotating. I did mount one side hydraulic arm but the rotation issue is present.
E58F05A5-1191-4190-9ECA-FCB3A86F2AEB.jpg

[srislash]

And I think the answer is in the picture that Ryan posted. The way that the center arm attaches to the drive should stabilize it. Thank you buddy.

[Fluid]

Many years ago, steerable outdrives were very popular on RTR boats. The power available with round cells was much less than what we have today, but we discovered that as we increased the speeds of the RTRs with better motors and more cells the boats gained a strong tendency to hook and spin out in the turns. This happened with all of the different outdrives boats the club members ran. Up to a point they performed well, then hook city. It will be interesting to see if the OP’s boat can overcome this tendency.


.

[srislash]

Many years ago, steerable outdrives were very popular on RTR boats. The power available with round cells was much less than what we have today, but we discovered that as we increased the speeds of the RTRs with better motors and more cells the boats gained a strong tendency to hook and spin out in the turns. This happened with all of the different outdrives boats the club members ran. Up to a point they performed well, then hook city. It will be interesting to see if the OP’s boat can overcome this tendency.


.

Haha, I had a Graupner Portifino that ran great for its time, then a Systems 7 catamaran from Graupner. Both with steerable drives. Hoping I can sort this out somehow. I just like the Arneson look.

Thanks Jay.

[fweasel]

And I think the answer is in the picture that Ryan posted. The way that the center arm attaches to the drive should stabilize it. Thank you buddy.

Glad it helped. Figured a picture of a known working setup, albeit HUGE, might offer a shortcut.

[srislash]

So lets see if I can get the pics straight if I go thru my laptop

IMG_2379.jpgIMG_2377.jpgIMG_2378.jpg

So i think I have the geometry right. I do need to rework the bracketry into something presentable. But I have 3/8" lift/swing and this should fair well on the 43" Magnum hull it will go on. Not sure if the fin laying over with it will help or not but it looks good to me.

I am thinking of have a chat with my favourite CNC machinist to see if we can make duplicates.

[fweasel]

Is the aluminum block off the transom just a spacer at this point to get the geometry right?

The swing looks perfect!

[srislash]

Is the aluminum block off the transom just a spacer at this point to get the geometry right?

The swing looks perfect!

Yes but there is lots of meat there that I can mill down into something presentable. Something triangular I’m thinking now. Perhaps 3 mount bolts at transom? Mmm

[RaisedByWolves]

Looks good.

Cant see the canted fin being a problem as it will be vertical when the boat is leaned into the turn.

[fweasel]

Yes but there is lots of meat there that I can mill down into something presentable. Something triangular I’m thinking now. Perhaps 3 mount bolts at transom? Mmm

I had assumed you'd triangulate the mount for strength eventually and that this was a mechanical proof of concept. Regardless of the final design, you're going to need a transom mounted GoPro to catch is in action!

[srislash]

I had assumed you'd triangulate the mount for strength eventually and that this was a mechanical proof of concept. Regardless of the final design, you're going to need a transom mounted GoPro to catch is in action!

Agreed, I like the cut of your job sir! Lol