KATO33 0 #1 January 20, 2003 Can someone give me a link or explain to me the formula for calculating a Spot. I vaugley remember Some thing about Calculating the windspeed at 3 or 4 different altitudes. I know this is something I should have learned in AFF but it wasn't stressed and I sorta trusted the JMs and Instructors to know. Blue Skies Black Death Quote Share this post Link to post Share on other sites
LouDiamond 1 #2 January 20, 2003 Do a search for a thread entitled "do bad spots exist" I forget which forum. I posted a PPT show and a word doc on how to calculate for the spot or HARP. If you have questions feel free to PM me."It's just skydiving..additional drama is not required" Some people dream about flying, I live my dream SKYMONKEY PUBLISHING Quote Share this post Link to post Share on other sites
dterrick 0 #3 January 20, 2003 There are really "2" spots... the exit spot and the opening spot. The opening spot seems to be the key until you start doing funky weird things with formations or high openings. On our C-182 dropzone the opening spot is calculated after throwing a wind Drift Indicator (WDI) If you're unfamilliar with its construction or use, go back to the SIM's and read the theory. Simply put, a WDI tossed at opening altitude will drift with the prevailing wind until it lands. This yields the lower winds' direction and strength. Since you drop the WDI right over the intended target, you then attempt to be at opening altitude and equal distance ON THE OTHER SIDE (180 deg) of the target. you are then fairly sure of making it home even under a round reserve. By the way, generally the pilot will fly into the wind at 2200 and you can normally assume the upper winds are of the same direction. Differences will often be declared by the pilot and your jumprun will be in a differnt direction than the one in which you threw the WDI. Exit point relates to how you will continue to travel in the direction of flight right after exit and then be puched back toward the dropzone along with the "column of air" you are flying. So long as ther uppers are not much differnt from the ground winds, taking the exit spot and moving again that far down jumprun before exit will getyou home 90% ofthe time. the other 10% you will have - - much higher uppers (eg) and you will be blown backwards much farther - so youtake the spot farther. you will also notice your apparent groundspeed to be VERY slow in a Cessna - uppers of a different direction. Then jumprun will still be into the wind but on a different heading. As you fall back into the lowers, your vertical flightpath will take a bananna shaped curve. Bad spots DO exist even on a Cessna DZ but the procedure as described is more than adequate. those who usedto jump rounds will have learned to spot much more accurately. "Turbine Babies" may only know to go on green. Freeflyers and bigway participants also have their own spotting issues because of speed differntials. Not doing AFF I got a fair chance to be on several low level jumpruns and I ALWAYS asked about "the spot". In Canada you need to be able to throw a WDI and calculate a proper sopt for your A license. you need to be able to calculate and execute a 4 way spot for your B. I could scan the relevant pages from our PIM's if you like but I'm sure its also in the USAP SIM's Dave Life is very short and there's no time for fussing and fighting my friend (Lennon/McCartney) Quote Share this post Link to post Share on other sites
billvon 3,070 #4 January 20, 2003 >Can someone give me a link or explain to me the formula for calculating a Spot. First calculate throw. That's how far the plane "throws" you, usually around 800 feet. Faster planes throw farther, freefliers throw farther. Next figure winds. Easiest way is to take the average of exit and opening winds/directions, or just take the winds at the halfway point (6000 feet.) Convert to feet per second, then just multiply by time in freefall to get how far you will move. Next figure where you want groups opening. First group should generally be slightly downwind (with a normal jump run) so that's your 'aiming' point. Finally figure out separation. Easiest way to do this is convert the aircraft speed to feet per second and figure out how many feet of separation you want. At 100 fps, ten seconds gives you 1000 feet. This works as long as the lower winds are lighter than the uppers and are in the same direction. Anyway, that's the 'rigorous' way to do it, but almost no one does it like that. They just eyeball it. Quote Share this post Link to post Share on other sites
councilman24 37 #5 January 21, 2003 As much as Dan doesn't need any help promoting himself see Parachuting, A skydivers handbook for a discussion. Best way to learn, JUMP A ROUND! I'm old for my age. Terry Urban D-8631 FAA DPRE Quote Share this post Link to post Share on other sites
LouDiamond 1 #6 January 21, 2003 Not bad explanations so far but if you don't all ready know how to do that stuff it really doesn't shed any light on your question. I recommend you look at the info I pointed you to . It has examples as well as practice problems with the answers and a worksheet you can take with you to any DZ and calc your own winds for both HALO (skydives) and HAHO(cross country) jumps. The PPT presentation is an actual class exercise you can use to answer your questions in detail."It's just skydiving..additional drama is not required" Some people dream about flying, I live my dream SKYMONKEY PUBLISHING Quote Share this post Link to post Share on other sites
KATO33 0 #7 January 21, 2003 Thanx Loudiamond In really appreciate the info and worksheets you provided that was exactly what I was looking for. Blue Skies Black Death Quote Share this post Link to post Share on other sites
