Tank and Helicopter Testing.
This afternoon my son started hydro testing all of the vehicle tanks. We had planed to test the entire vehicle with plumbing and everything, but with recent tank failures on the test stand and our sample heat treated tank we decided to individually test the vehicle tanks. The tanks were designed to be hydroed to 500PSI. However for the 90 second vehicle we did not ned to go so high. We backed off to 450PSI and still did not fair well. We tested all 8 tanks and got the following results: Failures at 350, 385,415 and 435. Four tanks passed all the way to 455. Since thanks are welded together in pairs we have one good pair, that will go on the test stand. The rest of the vehicle tanks are probably scrap. All four tanks failed in exactly the same way, at the interface between the endcap and the tubular tank. The weld stayed attached to the end cap and the weld pulled away from or failed at the tubular part of the tank. The tubular part is 6063 and the end cap 6061 so this failure mode sort of makes sense.This result really complicates the decision process. What do we have from last years effort? We have 1/4 of a vehicle tank. We have some structure. We don't have valves, plumbing electronics we can use. We think (confidence 80%) that we have motors that will work. Do we scrap the design for a simpler solution or do we fix what we know is broken? There is a strong desire to start over from scratch. If I were to start again I think I'd build a 3/4 scale pixel. However this would mean scrapping the one part we think we have working the motor. Arghhhh decisions and only 11 months to be ready.