I have been making several changes to my original model. I will continue to post updates.
--Josh
06/06/2008
06/07/2008, Top Motor flipped because the propellor would be above water when surfaced. Float tubes added. Two 1.5"x21.5" tubes for an approximate weight of -2.572 lb submerged:
Scale:
Approx. 22"L x 9.5"W 10.5"H.
06/08/08, OK I did some more work on the ROV today despite my busy schedule... The ROV without electronics(camera,lights,IR illuminator, H-Bridges, uC-Board, Tether Connector), but including 3 bilge pumps, has the following approximate properties:
I verified that the ROV will correct its orientation quite forcefully when inverted in water.
06/14/08, Switched to 3" PVC Pipe for electronics tube... awaiting two 3inch unions and polycarbonate sheets. The 3" pipe will be cut down to approx 10" long from the 24" visible in the picture below. Tests with the wide angle camera and IR illuminator went better than expected. Propellors were trimmed down to draw 6Amps@12.8v under 100% duty cycle and attached to the pumps via prop adapters. This slight overdraw will allow for a voltage drop across the tether, in addition to allowing the pilot to "turn the knob to to 11" if required for a brief maneuver.
Very Cool: My buddy Brian Watson, a Mechanical Engineer at NASA-JSC helped me analyze the safety of using 0.25" and 0.5" polycarbonate viewing panes at 328 feet. The result was that both were acceptable, with the 0.5" having a higher margin of safety. The mechanical properties chosen were the low end of the spectrum for polycarbonate, as detailed in the Properties page of the following pdf: Submaring Window Preliminary Analysis.
The tether with buccaneer connector, hacked joystick, and weight tube rods can be seen in the new pic:
06/26/08, Cut 3" dia circle out of 0.25" acrylic and used it to mount b/w board camera and IR illuminator. Machined a 10x3" piece of the same acrylic to mount electronics on. This piece will slide into the tube for easy loading. I Found out that the IR illuminator is very small after removing the "weatherproof" housing. I kept the housing(metal w/ o-rings) to make a future mini-submersible with. Also, my polycarbonate sheets and 7.2" tv screen got here today. I am happy with the tv screen dimensions, but the resolution leaves much to be desired, thought it is adequate for this project(especially for the price). The board camera and IR illuminator(links below) work great together.
I Measured power requirements today:
06/27/08. This week has been busy with my birthday and a physics exam. I have managed to get a lot of work done on the ROV. It looks different now and I should be able to get pics soon. Expected for a pool test to 10ft tomorrow!
07/06/08. No pool tests yet. Decided to use Urethane float instead of pvc floats. Expected mass = 5kg +/- 0.1kg
Progress:
07/07/08. Tested bouyancy today. Looks like I was too pessimistic with my estimations. The rov has a wet weight of approx 1.1kg without floats. I expect the cross sectional area to be ~0.039 m^2.
Resources: