godfrog 2 #26 July 6, 2011 Quote lol, I assume that was tongue in cheek? If not, I guess it depends on what the end use of the calculation is... If it was for a math or engineering class, I would at least want to know what the variables were to develop a valid and complete list of assumptions. I would hope that any instructor worth their salt would at least appreciate their students being thorough about examining a problem. __________________________________________________ It was tongue in cheek The gravitational variences are minor. Soooo...onto something better what type of drag should be considered the most important? form drag? parasitic drag? I guess it really doesn't matter as long as you can have enough control to accelerate and fall relative with those who you jump with... and yes this is all within the abilities of a jumper with reasonable experienceExperience is a difficult teacher, she gives you the test first and the lesson afterward Quote Share this post Link to post Share on other sites
JohnMitchell 14 #27 July 6, 2011 How about 10 seconds for the first thousand feet and 5.5 seconds for every thousand after that? It works pretty well for figuring belly delays. Quote Share this post Link to post Share on other sites
kallend 1,623 #28 July 6, 2011 QuoteQuoteQuoteWhere did you get your equations? I'm not necessarily saying they're wrong, just confusing to me... Breaking down the first eqn doesn't make sense how that could be right. if it is, it seems like it would have more to do with the linear momentum of the skydiver and not the drag. I could see how this eqn would make sense if it described the absolute velocity, but not if it's supposed to be for just one component (x or y). dVy/dt = ay = = Fy/m = g - (0.5*C*p*Vx^2)/m + (0.5*C*p*Vy^2)/m Because drag goes with v^2 (at the Reynolds Numbers involved) the x and y equations ARE coupled. You don't ALWAYS have to "get" equations from somewhere. You can work them out for yourself. Remembering back to fluids, the equations we worked with for lift and drag of an airfoil were what I was thinking of... Those equations had been simplified to only consider drag force opposite to the flight direction. I guess it just seems counter-intuitive that drag, resolved as a force, would effect an object from a direction perpendicular to the flight path. It doesn't. Both x AND y are involved in the free-stream direction when the flight path is neither horizontal nor vertical. Do the trig, resolve the forces, and work it out for yourself. I have my freshman engineers do it every year as an exercise in projectile motion with air resistance.... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites
kallend 1,623 #29 July 6, 2011 Quote How about 10 seconds for the first thousand feet and 5.5 seconds for every thousand after that? It works pretty well for figuring belly delays. Troublemaker!... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites
PWScottIV 0 #30 July 7, 2011 Quote How about 10 seconds for the first thousand feet and 5.5 seconds for every thousand after that? It works pretty well for figuring belly delays. Yeah, I concluded my first post with that estimate... I didn't know how thorough of an answer he needed.Gravity Waits for No One. Quote Share this post Link to post Share on other sites
JohnMitchell 14 #31 July 7, 2011 Quote Troublemaker! Damn right. They call me "Mr. K.I.S.S." Quote Share this post Link to post Share on other sites
JohnMitchell 14 #32 July 7, 2011 Quote Yeah, I concluded my first post with that estimate... I didn't know how thorough of an answer he needed. Gotcha.Although I appreciate an inquisitive mind, from reading some of his posts, I feel our new jumper is overthinking our rather simple sport. Quote Share this post Link to post Share on other sites
PWScottIV 0 #33 July 7, 2011 Probably... However, even before my first jump, which was AFF1, I had studied to a pretty extreme degree to develop a better idea of what to expect... I had read about every fatality, nearly finished reading the SIM, and had watched probably every AFF video online at the time. A bit extreme by most people's standards, but in my opinion, knowledge is power. With extreme sports, it could be the power to make the right decision that saves your life.Gravity Waits for No One. Quote Share this post Link to post Share on other sites
kallend 1,623 #34 July 7, 2011 QuoteProbably... However, even before my first jump, which was AFF1, I had studied to a pretty extreme degree to develop a better idea of what to expect... I had read about every fatality, nearly finished reading the SIM, and had watched probably every AFF video online at the time. A bit extreme by most people's standards, but in my opinion, knowledge is power. With extreme sports, it could be the power to make the right decision that saves your life. Having Mad Skilz helps too.... The only sure way to survive a canopy collision is not to have one. Quote Share this post Link to post Share on other sites
PWScottIV 0 #35 July 7, 2011 lol, true. Obviously, no amount of studying could replace what one learns from experience.Gravity Waits for No One. Quote Share this post Link to post Share on other sites
