User:Vincecate/Pipe Spar

Looking at Red Hawk Spar and thinking about using standard pipes to make a spar. Could have 1 pipe or maybe a group of 3 or 7 pipes.

First lets look at a single 36 inch sched-40 stainless steel pipe. This is probably 0.375 inch thick (nearly 1 cm). The density of stainless steel is about 8000 Kg/m^3 or 8 grams/cc. At 36 inches diameter it is about 287 cm in circumference. If we have a pipe 150 meters long this is 8*287*150*100=34440000 grams or 34,440 Kg. Stainless costs around $5/Kg with a pipe being a bit more than this.

If we have 20 meters above water we have 130 meters underwater. Displacement for 3 foot diameter pipe is 1.5*1.5*3.141592 = 7.069 cubic-feet per foot of pipe. With 426.5 feet underwater and each cubic foot of water is 60 lbs, then 7.069 * 426.5 * 60 = 180,885 lbs or 82,048 Kg.

After taking out the weight of the pipe, we have 82,048-34,440= 47,608 Kg for ballast and living space. If we use half for ballast then we have 47,608/2 = 23,804 Kg for living space.

Could use a thicker pipe and still have interesting size living space. Can also brace the joint between the pipe and the living space. Lots of lift really.

I would have the pipe closed off with an air valve that let me pump high pressure air into the spar. The high pressure air will help keep the pipe from ever buckling. Also, we can have an alarm go off if the pressure ever starts to drop (indicating a leak). Could use this as a air tank for Compressed Air Energy Storage. A bit harder for the computer to figure out if their is an air leak if we are pumping air in and taking it out to run generator, but can probably make something that would still detect any big problem.