ShortBus 0 #1 May 31, 2002 My friend Tim is a very cool guy he was in the Airforce for many years and was special ops. for quite a few years. So i guess hes really "educated" on air speed and what you can and cannot do. I told him today that myself and a friend of mine hit 220 this weekend doing a head down. His Pro-track wasnt on the fritz we were just haulin Ass. Once i metion this he immediatly says "impossible" he says that there is no way you could go faster then 170. Saying thats what terminal velocity is and you cant fall any faster without propultion. If someone could make clear exactly what Terminal Velocity really means that would help. Back on track... I also mention about the guy going up to 110,000 ft and making a jump and while he was in freefall he broke the sound barrer (sp)?... Once again he says "Impossible" going that speed would rip the skin off your body the guy would have to have armor up the wazoo to withstand even half the speeds and he was telling me how pilots cant eject that fast cause they would die and bla bla bla. He also mentions hot air ballons cant go above 40,000ft i tried arguing but im not educated enough to argue so all i had to say is "Well the pro-track said i was goin 220 and that i read an article about the guy doing the freefall and that a girl was also going to do it. After that i shut my mouth tucked my tail between my legs and ran straight to here. Someone please help me so i can Win this arguement i need help A.S.A.PThanks for taking the time to read this,dan =) Quote Share this post Link to post Share on other sites
skydiverbrian 0 #2 May 31, 2002 This one's easy. Teach him to skydive. Work sucks. Let's skydive! Quote Share this post Link to post Share on other sites
ShortBus 0 #3 May 31, 2002 Hes doing AFF this summer i managed to talk him into it but thats a while away and i cant let him beat me i mean comon everyone knows you can go faster then 170 look at the speed fliers who are getting close if not over 300mph so now i just need to be able to logically explain it......Grrrr my head hurts Quote Share this post Link to post Share on other sites
Rachill 0 #4 May 31, 2002 If you want to really blow his fuse, tell him a GIRL told you that she has gone over 240mph (me, headdown of course)...About the arguement...... I think your just going to have to say "I told you so" when the time comes...BLUE SKIESWhat happened to Turbo? He was to slow so we...... Quote Share this post Link to post Share on other sites
Zennie 0 #5 May 31, 2002 Ask him what terminal velocity in a vacuum would be.I'm sure some of the engineers with way more experience than me can answer this more technically, but basically terminal velocity is the speed at which the drag on your body is equivalent to the force of gravity such that you can no longer accellerate. By manipulating drag, you can thus manipulate your speed. And yes you can go 220. I've been 224 and ramon did like 270-something in a recent speed dive contest. How? By reducing drag. You can do this by reducing the drag your clothing causes (i.e. wear tighter clothes, or shorts) and you can reduce the amount of body surface exposed to the relative wind by taking a low profile orientation (such as head down).As far as high altitude jumps go, your Air Force friend may want to take jaunt over here and read about Col. Jospeh Kittinger. A brief excerpt..."on 16 August 1960, as an Air Force captain, Kittinger jumped from an open balloon gondola at 102,800 feet, the highest man had ever gone in an unpowered flight. He plummeted to earth, travelling 16 miles in 4 minutes and 36 seconds, before his main chute opened, the longest free-fall in history...Kittinger still holds the record for the highest parachute jump and first man to exceed the sound barrier (714 mph) in free-fall, for the Excelsior III jump. He has the most high altitude balloon flights (five): Man High I (96,000 ft); Excelsior I (76,000 ft); Excelsior II (75,000 ft); Excelsior III (102,800 ft); and Stargazer (86,000 ft)...""Zero Tolerance: the politically correct term for zero thought, zero common sense." Quote Share this post Link to post Share on other sites
billvon 2,772 #6 May 31, 2002 >Someone please help me so i can Win this arguement i need helpNo prob, we eat guys like this for breakfast!>I told him today that myself and a friend of mine hit 220 this weekend >doing a head down. His Pro-track wasnt on the fritz we were just haulin >Ass. Once i metion this he immediatly says "impossible" he says that >there is no way you could go faster then 170. Ask him what he thinks the terminal velocity of a 12,000 lb bomb is dropped from 20,000 feet. If he doesn't know, tell him about the TallBoy bomb, a bomb used during World War II - he should like the military reference. It had no propulsion yet fell much faster than the speed of sound. (3600 feet per second.)Once he buys this, ask him if higher weights and more streamlining might have helped the bomb go fast, and suggest the same might apply to people.> I also mention about the guy going up to 110,000 ft and making a jump and >while he was in freefall he broke the sound barrer (sp)?... Once again he >says "Impossible" going that speed would rip the skin off your body the guy> would have to have armor up the wazoo to withstand even half the speeds and> he was telling me how pilots cant eject that fast cause they would die . . .Tell him Kittenger _was_ wearing armor (pressure suit) and that his jump was to test ejection systems specifically for that purpose.> He also mentions hot air ballons cant go above 40,000ft Kittenger used a helium balloon. They can easily get above 100,000 feet, and are often used for near-space research.-bill von Quote Share this post Link to post Share on other sites
Dumpster 0 #7 May 31, 2002 Suggest he take a trip to the Air Force museum at Wright-Patterson Air Force Base - They have a nice little display there of Col. Kittenger's record-setting little jump- I've seen it myself! Lots of other really cool stuff there too-And I'm just a slow-poke- I've only been up to 154 myself in a track- Quote Share this post Link to post Share on other sites
PhillyKev 0 #8 May 31, 2002 well...i spent a few minutes typing up different definitions and explanation of terminal velocity, but wiped out the post. do a search on google for terminal velocity, and you'll get all the info you need.cielos azules y cerveza fría-Kevin Quote Share this post Link to post Share on other sites
PhillyKev 0 #9 May 31, 2002 Here you go...excerpt from a physics book and directly related to skydiving. Included info about Kittingers jump and has bibliographical references.This will shut him up.cielos azules y cerveza fría-Kevin Quote Share this post Link to post Share on other sites
faitor 0 #10 May 31, 2002 Another important fact sometimes overlooked it that the speed of sound is not constant. Here is a helpful link to explain.SPEED OF SOUND Quote Share this post Link to post Share on other sites
drenaline 0 #11 May 31, 2002 QuoteSaying thats what terminal velocity is and you cant fall any faster without propultion.Terminal velocity is the maximum speed you can get in relativity with your position, in belly to earth it can be one speed, in head down it can be another and so in sit. You can't judge terminal veloxity cause only one man can make 170 in his belly to earth, others can do more and others can do leess, its all relatively with his weight, position, the wind and the drag you give, the less drag you have (perfect head down) the faster you can go. Thats my 0.02. If I weren't so drunk I qould off told write the equation and the explanation in number, ask a physic to calculate that for you.Don't worry, if it were people like him, we wouldn't be able to freefall and do some RW. In the beginning people used to say that you couldn't controll yourself while in freefall and that the pressure would be such that you would never be able to pull your rip cord, and now we all know that it was a big lie and that it can be done."Life is full of danger, so why be afraid?"drenaline Quote Share this post Link to post Share on other sites
flyhi 24 #12 May 31, 2002 QuoteAnother important fact sometimes overlooked it that the speed of sound is not constant. Here is a helpful link to explain.Rumor has it that the speed of sound (in feet per second) is only temperature dependent, and is equal to 49 times the square root of the temperature in Rankine (R = Fahrenheit + 460). At least, that's the rumor.flyhi Quote Share this post Link to post Share on other sites
Pammi 0 #13 May 31, 2002 Very interesting thread! There are some damn smart jumpers out there! 'Nuthin Quote Share this post Link to post Share on other sites
kmcguffee 0 #14 May 31, 2002 If I remember correctly from fluid dynamics-terminal velocity = sqrt (2W/Cd r A)W = weightCd = coefficient of drag. Found experimentally but changes based on the area of the body presented to the relative wind. Includes all forms of drag ie skin drag (type of suit), form drag (shape of body), and induced drag (wingtip vortices type drag).r = density of air (the less dense the air is ie the higher you start the fall from, the faster the terminal velocity is)A = area of the falling body presented to the relative wind. If you increase the area (boxman, birdman suit) your terminal velocity slows. If you decrease your area (head down) terminal velocity increases.When the force of drag on the body equals the weight of the body then acceleration becomes zero and you are at terminal velocity. If you assume that your weight is constant (it actually isn't but the change is negligible for our purposes) then the only thing you can effect is drag.The Fluid Dynamics book I'm reading from is 12 years old but all of this is should still be correct.Basically, what all of this says is that there is no arbitrary cap on terminal velocity of 170mph."Some cause happiness wherever they go; others, whenever they go." Quote Share this post Link to post Share on other sites
hanknotdan 0 #15 May 31, 2002 Anybody else bothered by the fact that someone who was in the Air Force for years knows so little about freefall and flight characteristics? Your tax dollars hard at work. Quote Share this post Link to post Share on other sites
billvon 2,772 #16 May 31, 2002 >Anybody else bothered by the fact that someone who was in the Air Force for> years knows so little about freefall and flight characteristics? Your tax dollars> hard at work.How many professional pilots know that stuff, or even understand basic fluid dynamics? There are plenty of air force people who don't understand aerodynamics, just as there are plenty of navy people who don't understand Boyle's Law, or what decompression sickness is. People are, in general, only as smart as they need to be (and sometimes not even that smart.)-bill von Quote Share this post Link to post Share on other sites
Zennie 0 #17 May 31, 2002 QuoteHow many professional pilots know that stuff, or even understand basic fluid dynamics? True. We're sort of unique in that we're our own lab rats. We've grown to understand this stuff intuitively. "Zero Tolerance: the politically correct term for zero thought, zero common sense." Quote Share this post Link to post Share on other sites
FallRate 0 #18 May 31, 2002 ShortBus, most of your argument is true, but Kittinger didn't actually break the sound barrier. His speed at 714 mph would be greater than the speed of sound near the surface of the Earth, but it was not greater than the speed of sound relative to where he was in the atmosphere (temperature or altitude, whichever). That is one of the things which will make Cheryl Stearns' attempt quite unique (if it ever happens). She will actually attempt to go through the "sound barrier" and if she does will experience the shock waves.FallRate Quote Share this post Link to post Share on other sites
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