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PostPosted: Thu Apr 01, 2004 11:46 pm
by Barry
Someone mentioned that the shock load increases as pilot weight goes up. I was taught that manuvering speed is higher while at gross weight, meaning shock loads go down with more weight. Could someone verify this. I'm only 140lbs so I try to keep the speed under 30 on bumpy days but sometimes its not easy when you are on a rollercoaster.

PostPosted: Fri Apr 02, 2004 3:16 am
by ozzie
hi barry' yes as weight goes up your manouvering speed goes up as well same for all your speeds t'off stall landing they will all rise. weight creates speed, speed creates lift. wing loadings must increase as weight goes up the limited wing area dictates this. now as the weight increases the airframe will have a bit more enertia so when it meets an obsticale (a parcel of air moving in a different direction than the air surrounding it) the airframe will have more stored kinetic energy to penetrate that air before it diviates from its direction of flight. the time frame is small . the loadings (G) will be very high but for small time( milliseconds) But any failure will be very rapid and loud (explosive). i certified the Thruster wing in1985 and had it hung upside down with it attatched to the wall. it had been loaded to it's design limits with brick pavers and sand bags, signed it off and then went another 40% more in weight and signed it off again with the dept. watching. it was groaning and creaking and would have failed in ten minutes or so. as an experiment i took a handful of wet sand ,compacted it into a ball and slow tossed it so it fell straight down on the wing. it totally collapsed very quickley and loudley. That simulated the affects of shock loading on a wing that was right up there as it was, like doing aerobatics and hitting a thermal. there is a documented case of in flight failure in a assender racing home at full power and hitting some mechanical turbulance and the wing failed.
See if you can get your hands on a flight manual of say an Islander or Twin Otter something that can carry a bit of weight and look at the speeds at different weights. it shows a bigger easy to see comparison than the one or two mile an hour difference in a Lazair