I love Body-Boards.
They are poor man´s surfboards for for non-hawaiian non-californian or non-seaside residents like me.
A Body-board should be the ideal platform for carrying all that electronics.
How was i wrong!
The only thing which was missing is an adequate propulsion system.
The first try was an electric bilge pump. As already mentioned above, i don´t like propellers in the water, because they will easily fall in love with water-plants.
A bilge-pump seemed the ideal solution, because it has a shielded propeller, which is well adapted to the motor by a gear.
The outlet of the pump was connected to a silicon tube, the steering was done by a servo that bent the tube to the right and the left.
Yes it worked - in principle -
But the thrust of the pump was not high enough to get an adequate speed and the tube-bending assembly had not enough "angle" to make good turnrates.
Sorry, no pictures are left from that assembly.
Still the idea with the body-board.
I skipped the idea with the bilge pump, anyway a model with a better throughput may have done the job....
Till this point all assemblies have been very very crude ones, stucked together with gaffer-tape and hot glue. The only purpose of this assembles was to prove, if the concept is OK.
Till then it obviously was not.
Then i went in a more serious phase, when i entered again the local RC retailer shop and left it with a BLDC Motor-propeller assembly from Multiplex.
It was a kit for pimping the Park Master from Multiplex, the "Power drive "ParkMaster 3D" #332638". See /http://www.multiplex-rc.de/ for details.
The Parkmaster pimping kit.
This kit was mounted on an alumnium plate, which was recycled from an old 19" rack. The steering was done by an air-rudder, which was made from a PVC foam board. It looked a little bit like an oversized side-ruder of a model plane. Thrust was OK now, but the steering was not. In principle it worked, but the air-rudder had not enough "power" to give a good steering quality. Additionally, the left and right curve radiuses (or is it radii ?) were different, because the simple "steel-wire-rudderhorn-servo-coupling" was not symmetric.
And, most of all, the body board had no keel, which makes it very instable. Holding a straight-line course is like juggling with three balls (and i hardly can do that with one). Adding a few stripes of PVC-foam-boards on the bottom of the board made it better but not good enough.
This is the Body-Board with the air-rudder. Still with telemetry, still RC controlled.
Next Try: I mounted the BLDC Motor with the propeller on a PVC Tube and put it on a PVC pivot so that the whole assembly can be turned by a servo. Looks a little bit like a windmill. This led to better results for the control of the Body-Board, but the stability for driving a straight line was still not satisfying.
The first approach was to connect the PVC tube to the servo by an an O-Ring. Worked, but was a little bit sloppy when the tension on the O-Ring is too low and gave to much force on the shaft of the servo, when the tension was OK. So i decided to connect it "classically" with steel-wire and rudder-horns.
I kept this propulsion-approach for all further platforms, because it proved to be very robust.
The Windmill assy with O-Ring connection. Sloppy...
The Windmill assy with steel-wire and horns. much better..
Thats all for today, next episode will focus on a more serious hull, the introduction of ArduPilot and the black day.
Comments
Eagerly following this because I am thinking about putting an ardupilot on a RC sail boat, and want to see what we can learn together.
I've played with RC airboats in the past. You have to really work the controls to keep them going striate. Turning response is also dependent on applying power, so if you throttle back you loose the ability to steer.
I like the propulsion coming from the air. Up out of the weeds, but I think it may be much easier to use keel and rudder in the water to keep it going where you want it to.
Troy
for such things i have been looking for one year in the past.
800mm length should be OK, catamarane rails also. The problem will be:
Will it still glide with about 2kg of payload gear on it ?
Hmm.. Catamarane submarine -something to think about :-)
But anyway, if you are looking for an additional project, ArduPilot will be a good add-on.
It's called Galaxy Airboat, can easily be converted to brushless and offers some space for additional gear. I may be a "pro" replacement for the body board? It's 800 x 350 mm in size.
Unfortunately, it seems not widespread in e-shops.Nice project you got there :)
don´t tell my secrets... :-)