Salt Water has a density of ~ 1g/cm^3, so I would need my Total Displacement to equal my total mass to be neutrally buoyant. I wanted the ROV to be positively buoyant. So I needed 7 times the displacement that I had for the mass of the ROV. neither the mass could have been reduced by 7 times, nor could 7 times the displacement in buoyant materials be added with this steel design. So I had to redesign the whole ROV in aluminum.
So I sat down, researched aluminum specs, considered and sketched every design possibility for the seal, found a tube that worked with one of them, and sat down to design the whole thing over again.
This time around, I measured the required clamping force for the new O-Rings. The chart for 90-Shore A O-Rings, the clamping force chart was very confusing. So I took the highest value on the table and used that.
After running the calculations for the clamping force, I came up with 2000 pounds of force required. I spread this across 8 bolts and applied a safety factor of 10 to keep the bolts under-strained. I ran the tensile strength calculations bolt sizes and came up with 10-24 bolts to be the best option.
Because I am now using 2 different metals, I will have to deal with galvanic corrosion. I looked into physically separating the metal parts, however this would have added several extra points of failure. I decided to instead use a sacrificial anode.
I re-did the buoyancy made a draft of the new frame design and ran force strain studies on it to determine how to finalize the design.
I then researched buoyancy materials because the the extra buoyancy tubes would have added more points of failure. I found Syntactic foam to be the best option. It is machinable and readily used.
The next day I found a CoB LED for the lights. It is 36V, and 3000 Lumans. I then designed a light module around the LED.
On Thursday we looked at an auction to find stuff for the shop.
I found a $1100 dollar video camera setup for $250, with a wide angle lense that would be perfect for the ROV. I also found a shelf full of carbon fiber rods that would be perfect for the linear aspects of the ROV frame. I asked Mr. Christy to bid on both for the robotics team.
