pic: Recycle Rush Re-design Part 2

[Ari423]

Originally Posted by GeeTwo

Let's start with a 7 gal (1617 cu in) charged to 117.6 psig (that's +8atm, selected to simplify the math). As we regulate this down to 58.8 psig (+4 atm), we are making 1617 * 4 = 6,468 scfm, or 1,293 cu in at +4 atm (58.8 psig). Multiplying this out, I show a potentially usable energy of over 76,000 lb-in. A tote weighs 7.8 lb, so that's about 9,750 tote-inches, or 5 totes times 1950 inches. If each lift is 25", this is still a total of 78 lifts. That's 78 lifts of 5 totes 25 inches. There were only 30 totes behind the walls, so even without doing any optimization beyond not pressurizing the down stroke, there is more than twice the required energy in one 7 gal tank to stack all of the totes behind the wall. (Though I haven't done any flow calculations to determine if it can be done in 2:15!)

With a 10 pound air tank, this obviously won't get down to 15 pounds, but I expect that it can be done for well under the available 35 pounds, including tank, cylinders, frame, tether, and electronics.

We went the pneumatics route this year, so I have some first hand results as to how our testing went. Not powering the downstroke sounds like a good idea until you learn that most solenoids need 20 psi minimum on each side to open and close properly. We eventually decided on 15 psi, and it was still very slow going down. Also, don't forget that once your tank drops below 60 psi, you will see decreased performance. For this reason, we went with slightly bigger cylinders at 30 psi so we wouldn't see that effect until later in the match. No matter the size of your air tanks, at 60 psi you will see that effect halfway through your lifts.

Also, if you did what many teams did this year and let the second tote fall into the first one without lifting the first one, you will only need to lift 4 totes per 6 stack, not 5. You also won't need to lift them as high, only from 1 tote high to above the chute instead of from the ground. IIRC that's less than 25". Or you could do what we did and build a ramp attached to our stacker for the totes to slide to (almost) ground level, then you only need to lift the height of one tote.