Yep that is true: engine is big compressor.
those bags are great, we used them in Air Force for lifintg damaged air craft that had landing gear problems, worked pretty well all you need is a few PSI to lift tons of wieght! we had to TEST inflate ours every so often and they were stored in a semi trailer which we had all the liftin gslings and such in too. so we would lift the semi trailer a bit to TEST them... /forums/images/graemlins/smile.gif
they are also used by fire & rescue depts all over... to lift cars rucks ect. often used to help right a tipped over semi truck... of corse the size inflated all depends on the bag size too... small to large ours were somethign like 4'x4'x4' when fully inflated if I'm remembering right... dry weight was WAY up like 200 lbs or soemthign. took 2 people to drag them around. (when I say DRAG I mean lift and move onto a cart and then set into postion as any abrasions can casue a rupture and a blow out on them will cause major problem if the item is lifted and then pops a bag!!! it will fall pretty quick... /forums/images/graemlins/blush.gif
Mark M