James bond lotus submarine

[ffr2608]

The James Bond “Wet Nellie” is here! Bob sent me the prototype print this week and it is pretty much flawless. This project started several years ago with a CAD modeling project I took on for some training. Not many understand the differences between a real Lotus Esprit and the submarine movie prop. I spent many hours collecting photos to create a model that is true to the movie prop and not just an adjusted car model. Built as a wet boat with scuba divers inside, the hull was split horizontally along the cars signature character line. A perfect subject for a 2 piece fiberglass mold.
On to the model….
Printed in a high strength resin, the model is 22.5” x 9.5” and a perfect match for one of the available watertight boxes from S3. Bow and stern planes, rudders, antenna and 4 pump jet propellers finish up the package. Finish is amazing and will only require a couple rounds of primer for a nice surface. I think the biggest job will be masking for all the black trim and details….

https://www.rc-submarine.com/product-page/james-bond-s-lotus-submarine-from-the-spy-who-loved-me?utm_campaign=afccf4ff-2d64-4ec9-a8e3-c80f1079da8a&utm_source=so&utm_medium=mail&cid=7e307840-e8ea-4d9c-a0fc-1d35385b40a4

[ffr2608]

So excited to be back at a build thread. These really help to keep me motivated and get the boats to the water. The goal for this one is Subfest 2024 and that should be pretty realistic. I also hope to attend the Divetribes again so that should be fun.

First part will be the propulsor section. I plan to use the 2 outside shafts for the boat but haven’t decided on how to drive this thing. Here are the options…

Brushless in the wet or brushed cans in the pressure box.
Differential steering or use the supplied rudder's.
Old school skysport radio or modern radio to use the available mixing functions. I could use some help on this because there are no brushless dual esc’s available out there.

[ffr2608]

Some images of the shaft install and layout. The bores are just undersized enough to run a drill through them and bond in the brass. Next will be the bow and stern planes.

[tifosi12]

Very cool and glad to see you post even after April 1st. Wasn't sure whether this was for real or not, but Bob's website has it now for sale, so it must be real.

To me that's a dream come true for a long time. I have the 3D model of the car but never took the plunge to actually print it since the thing is fairly big and would take forever on my printer. But buying the model from Bob is a true alternative.

I would go with two brushless in the wet motors and differential steering. Keeping the mechanics as simple as possible, no rudder.

How will you control pitch? I saw once one approach where somebody used a shifting weight inside the cabin change the CG. Or are flaps at the rear the way to go?

Looking forward to your build. Once Bob has an instruction video out there, I'll have to get the model from him as well. Running this in our pool would be too cool.

[tifosi12]

Some images of the shaft install and layout. The bores are just undersized enough to run a drill through them and bond in the brass. Next will be the bow and stern planes.

What tiny motor is that? Never seen one that small.

[wlambing]

Seeing the 1:1 scale in Sardinia during filming of the movie was way cool! A perk of service in Uncle Sam's Canoe Club. Would rather have seen Caroline Munro, but that was not to be...

[ffr2608]

Not an April fools joke I promise.
The outrunner shown was just a placeholder. Going with a larger diameter and lower KV on the 2 outside shafts. As for the planes, I plan to run the bow for now and leave the stern fixed. I can easily add a servo to the stern planes later so that seems like a good starting point.

[He Who Shall Not Be Named]

Not an April fools joke I promise.
The outrunner shown was just a placeholder. Going with a larger diameter and lower KV on the 2 outside shafts. As for the planes, I plan to run the bow for now and leave the stern fixed. I can easily add a servo to the stern planes later so that seems like a good starting point.

Recommend you make both sets of planes active and Y-connect the four planes so you can V-tail mix them to induce roll -- that way you can bank into the turns and not do that awful looking 'slide' turn. I hate that!

David
Spewer of Unsolicited Advice

[tifosi12]

Not an April fools joke I promise.
The outrunner shown was just a placeholder. Going with a larger diameter and lower KV on the 2 outside shafts. As for the planes, I plan to run the bow for now and leave the stern fixed. I can easily add a servo to the stern planes later so that seems like a good starting point.

Interesting.
I was actually thinking to control all 4 planes simultaneously with one servo (e.g. fwd down, rear up and vice versa).

Looking forward to see what results you get with just one pair of planes.

[tifosi12]

Recommend you make both sets of planes active and Y-connect the four planes so you can V-tail mix them to induce roll -- that way you can bank into the turns and not do that awful looking 'slide' turn. I hate that!

David
Spewer of Unsolicited Advice

Obviously that would be the most advanced approach.

How did the original behave in the movie? I don't recall it doing tight turns, but has been years since I saw that. With those two divers pedaling inside they probably were just happy to move at all. Must have been hard work to get this thing going.

[ffr2608]

I already have 2 servos laid out for pitch. A mixer to get banking was always part of the plan. I am just not sure how to incorporate the stern planes with this. Lot's of linkage space around the pressure box so it can be adjusted after initial testing is complete. If you guys can point me to a modern computer radio solution, I can mix the heck out of the controls. Love my OpenTX radios and all the programming options on my surface craft.

[wlambing]

It kind of wallowed around like a drunk sea-turtle at a frat party.

[tifosi12]

It kind of wallowed around like a drunk sea-turtle at a frat party.

Ideal to precisely shoot a helicopter out of the sky.

[Subculture]

I could use some help on this because there are no brushless dual esc’s available out there.

If you're going to use differential steering with brushless motors, then I'd look for some esc's that have a very smooth startup.

You can use ESCape32 firmware on some blheli32 esc's if you're not squimish about burning a bootloader and firmware. That gives the esc's a rock crawler mode, so super smooth start-up like a sensored brushless motor or brushed motor.

[ffr2608]

Good call Andy. I have had good luck with some non-sensored on a boat but a couple brushed can motors would make things super easy. I prefer dry electronics over "in the wet" any day.
This is my big PCF using mixed throttles on the left stick. Very easy to dial in the steering with a computer radio.

https://www.youtube.com/watch?v=Im4J9NrvYko