airgord 1 #26 January 16, 2004 So, what is the air speed velocity of an unladen swallow? Quote Share this post Link to post Share on other sites
quade 3 #27 January 16, 2004 Tangential to the main topic put relevant . . . Quote Went and checked the literature on interference drag. Needless to say, no-one seems to have ever made measurements on human bodies. However, there's lots of data on cylinders. It seems that 2 parallel cylinders (like skydivers bodies) with space between them equal to their diameter (like in a compressed accordion, or a tight star formation) have additional drag of around 40% as compared to their total drag when widely separated. This is a BIG drag increase and could slow a formation a whole lot. The interference drag decreases rapidly as the spacing between cylinders is increased. So, when tracking, legs together, apart 6 inches or wide apart? Arms? Fingers?quade - The World's Most Boring Skydiver Quote Share this post Link to post Share on other sites
rehmwa 2 #28 January 16, 2004 QuoteSo, when tracking, legs together, apart 6 inches or wide apart? That's a great question. We're looking for drag to track flat and still have a good angle. Since the columns of your body parts do bring along a boundary layer that 'acts' like more surface area, I'd think that spreading out a little bit helps, especially towards the legs (you want a ton of lift in the legs and feet, right? not a hard dive, but high tail lift - I know, oversimplified). I 'think' I track best with legs apart a bit and arms fairly close in, but it's all relative to whoever I'm passing or being passed by. You ever drive with your hand out the window and try different cupping and finger spreading and seeing which gives the most resistance? I bet most skydivers have.... ... Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants Quote Share this post Link to post Share on other sites
darkwing 4 #29 January 16, 2004 Quote Went and checked the literature on interference drag. Needless to say, no-one seems to have ever made measurements on human bodies. However, there's lots of data on cylinders. It seems that 2 parallel cylinders (like skydivers bodies) with space between them equal to their diameter (like in a compressed accordion, or a tight star formation) have additional drag of around 40% as compared to their total drag when widely separated. This is a BIG drag increase and could slow a formation a whole lot. The interference drag decreases rapidly as the spacing between cylinders is increased. How big were these cylinders? Scale makes a big difference I think. For this information to be meaningful they would have to be about human size, and going about freefall speeds wouldn't they? -- Jeff My Skydiving History Quote Share this post Link to post Share on other sites
rehmwa 2 #30 January 16, 2004 Practical testing is called for here. This is too theoretical. Who wants to go to the tunnel? ... Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants Quote Share this post Link to post Share on other sites
rehmwa 2 #31 January 16, 2004 QuoteSo, what is the air speed velocity of an unladen swallow? African or asia ... Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants Quote Share this post Link to post Share on other sites
SouthernJumper 0 #32 January 16, 2004 i wanna goto the tunnel when u up for it Quote Share this post Link to post Share on other sites
kallend 1,623 #33 January 16, 2004 QuoteSo, what is the air speed velocity of an unladen swallow? African?... 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 #34 January 16, 2004 QuoteQuote Went and checked the literature on interference drag. Needless to say, no-one seems to have ever made measurements on human bodies. However, there's lots of data on cylinders. It seems that 2 parallel cylinders (like skydivers bodies) with space between them equal to their diameter (like in a compressed accordion, or a tight star formation) have additional drag of around 40% as compared to their total drag when widely separated. This is a BIG drag increase and could slow a formation a whole lot. The interference drag decreases rapidly as the spacing between cylinders is increased. How big were these cylinders? Scale makes a big difference I think. For this information to be meaningful they would have to be about human size, and going about freefall speeds wouldn't they? Re around 500,000... 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 #35 January 16, 2004 QuotePractical testing is called for here. This is too theoretical. Who wants to go to the tunnel? Seriously, this would make a neat project.... 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
rehmwa 2 #36 January 16, 2004 QuoteRe around 500,000 That's pretty big, er no, that's pretty small no, wait In college, I alway found reynold's number stuff much harder than even sonic and supersonic theory. I guess that's why I'm in management now. Those that can't do - look annoyed and keep pushing for RESULTS. ... Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants Quote Share this post Link to post Share on other sites
