BMoto Desktop Surfer - with Radio Control??

Balduccimoto

Balduccimoto

Location
NYC/Long Island
Since I began making the desktop surfer, I had always wanted to make it RC with a DC motor. A few people suggested some components I can use and now I am really considering it. I want to use the existing model and scale it up ≈ 200%. That makes it ≈ 11" long, and 3.6" wide.

Do you all remember the tech deck's of the 90's? That is the idea behind this. A small RC jet ski that is capable of multiple backflips, fist pumping, and world final worthy action that you can compete with your friends and annoy your family at your next pool party.

There are many jet drive assemblies already available such as this one:
http://www.ebay.com/itm/2-pcs-New-N...416158?hash=item2ed7c39a9e:g:0T0AAOSwxYxUv1cg
What I dislike is that they are nearly 4" long. Why am I going to bother when I already have a pretty damn good pump tunnel on the existing model? So I want to make my own that is a close replica to a Superjet drivetrain.

For the RC experts here: I don't understand how RC jet boats are sealing their driveshaft? I've seen a brass sleeve with a nylon insert so a 3mm driveshaft can go through. I would think that would be sufficient for sealing, but what about friction? I think that would get extremely hot and load the motor.

The driveshaft/pump assembly is the largest hurdle right now. I am sure at that scale I can find room for a DC motor/battery/electronics.

I will be documenting the entire build here. If you haven't checked out the current (mini sized of this project) 'Desktop Surfers' check it out here: http://www.bmotoshop.com/collections/personal-watercraft/products/desktop-surfer-jet-ski-model
 
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Balduccimoto

Balduccimoto

Location
NYC/Long Island
and so it begins.. The top deck weighs 70 grams. The current goal is to make a model at 200% scale and then decide how to make this happen.

IMG_1616_zpsqkruvk0w.jpg

IMG_1617_zpsgmcypenx.jpg
 
Balduccimoto

Balduccimoto

Location
NYC/Long Island
The first 200% scale model is somewhat finished. I like the size.. it comes to approximately 10" long and it weighs only 0.51lb (or 250 grams)

I haven't decided on a final design for the driveshaft and impeller. The pump has a very low center of gravity just like a full size jet ski and the current pump tunnel has a 15mm bore. There isn't any more room to make it larger without increasing the height of the bottom deck.

It will be impossible to align the center shaft of the DC motor with the driveshaft. I will have to use pinion gears to raise the DC motor a bit in the hull. Right now I am leaning towards a free-floating driveshaft design like the full size counterpart. The issue is that there needs to be some sort of stop. It's difficult to put this in words. If I can find the time I will upload a cut-away drawing of the hull. I do know that it will probably be using a threaded shaft with the impeller threaded on and the other end keyed for a pinion gear fixed with a set screw.

It should be no problem to get a small enough servo and shaft for the turn nozzle. The challenge will be fitting everything in such a compact hull.

and here are the photos - because build threads are nothing without photos.

IMG_1639_zpsyzi15xga.jpg

IMG_1640_zpseqlqmkj2.jpg

IMG_1641_zpsttjw35zy.jpg
 
Yami-Rider

Yami-Rider

TigerCraft FV-PRO
Location
Texoma
i would say, find a small jet pump unit (like the ebay link) and build the hull around it. The also make billet jetpump units with replaceable impellers, but your talking big bucks.

I have been into large scale high powered 2 stroke gas r/c boats for a while.

If you end up using a brass tube for the driveline, i would recommend not running a teflon liner, they end up doing more harm then good. Just use a quality marine grease and you wont have any leaks. My boat tops out at 66mph and doesn't leak in a drop.
 
Balduccimoto

Balduccimoto

Location
NYC/Long Island
Yami-Rider said:
i would say, find a small jet pump unit (like the ebay link) and build the hull around it. The also make billet jetpump units with replaceable impellers, but your talking big bucks.

I have been into large scale high powered 2 stroke gas r/c boats for a while.

If you end up using a brass tube for the driveline, i would recommend not running a teflon liner, they end up doing more harm then good. Just use a quality marine grease and you wont have any leaks. My boat tops out at 66mph and doesn't leak in a drop.
Click to expand...

Those jet pump units ive seen are very large, I would have to go to a much larger scale. I have an idea of what I want to do, but I need to find or make an impeller at around 15mm diameter. I can go a little bit larger or smaller, but not by much.
 
Balduccimoto

Balduccimoto

Location
NYC/Long Island
naticen said:
It'll probably be out of my price range but I'll fantasize about driving surfers mad anyways. You gonna put a dude on top of it?

Click to expand...

I have no intentions to, I would rather leave that up everyone else. There are companies that will 3D scan you and print a scale model of you. That would be very cool!

As for pricing I would like to keep it affordable, but it is too early in development to make any kind of assumptions.
 
Balduccimoto

Balduccimoto

Location
NYC/Long Island
Moving at a snail's pace trying to figure this all out. I may have to get a custom pump/driveshaft machined for this project. The pump tunnel is too pretty to toss the whole rear section of the ski away for a premade unit. Also premade units begin with an impeller that is 28mm in diameter.. The absolute max I can get out of the 200% scale is a 15mm diameter. In order to fit a 28mm impeller, I would have to scale up to 375% scale which is 20 inches long. That is something I wouldn't like to do.

I designed the turn nozzle and it's going to be driven by a mini servo and a long rod. I was able to get some crazy throw out of the nozzle also. Here's a teaser photo..

Section%20View%20Pump_zps2s7xwlgx.jpg


You can see by the photo that the driveshaft has a very low center of gravity. I can cut more into the bilge, but it's not going to help much. Probably enough room to fit a pinion gear.
 
Balduccimoto

Balduccimoto

Location
NYC/Long Island
I put in a little time this morning and made some progress. I figured out a clever way for water cooling and the nozzle is fully functional.. I got 67 degrees of nozzle rotation and it looks like it has just as much as the full size counterparts. Of course everything is conceptualized so not much has really become physical. I know the nozzle works great because I have a functional one in my hand, but as far as the linkage - I can't be so sure because I am down to .01mm tolerances. It might be time to upgrade the linear bearings on my printer and see how tight of a tolerance I can get out of it. That is all just planning ahead.

Here are some pretty CAD renders :D

Superjet%20RC_zpsp1zf1w8l.png

RC%20Superjet2_zpsdfxuhjdx.png
 
Balduccimoto

Balduccimoto

Location
NYC/Long Island
Project still alive and very close to first prototype. I am working on the impeller and I have a bit of learning to do. I simulated the first impeller via CFD and the results were crap and so I found a program that runs on MatLab command line that hopefully will help me get close enough to tweak it via CFD. These are going to be impressive little skis and should be available shortly before Christmas.
 
C

cmj

Location
Indiana
Balduccimoto said:
Project still alive and very close to first prototype. I am working on the impeller and I have a bit of learning to do. I simulated the first impeller via CFD and the results were crap and so I found a program that runs on MatLab command line that hopefully will help me get close enough to tweak it via CFD. These are going to be impressive little skis and should be available shortly before Christmas.
Click to expand...
Still here, still interested. Carry on!
 
Balduccimoto

Balduccimoto

Location
NYC/Long Island
This project has become my obsession.. Many changes since I last updated this. I won't fill in all the details, but I will say that I ended up using an impeller from a RC boat twice the size.. The intake completely dominates the bottom of the hull. The BOM is already at 60 parts .. Here's a teaser:

RC%20Jet%20Ski4_zpsnl65dlil.png

RC%20Jet%20Ski3_zps4uk7hfwd.png


The tray's mat above is probably going to be 1/16" tool box mat unless someone else has better suggestion? I already have a template made for it. I'd really like to have them laser cut but im not sure if that material can be laser cut? It has some pretty good texture to it.
 
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Balduccimoto

Balduccimoto

Location
NYC/Long Island
Here's a little peak into the engine bay.. The hood gasket is thin weatherstripping. I still need to figure out hood hooks. The servo is in a pretty useless spot right now. I really need my order of parts before I start chopping up the hull to run steering cable and servo mounts..

RC%20Jet%20Ski6_zpsqzddrjz7.png
 
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