sacex250 0 #76 June 11, 2011 QuoteOut of interest - have you ever tried your flat-turn experiment? Have you ever flown a parachute in 40kt winds? I was using Bill's example. So, if you took a fish up in an F-16 and did a 9G turn, you don't think that the fish would feel the force of the change in direction? I guarantee that the fish would feel the 9G's. If you took the fish up in the parachute experiment, the fish would also be able to feel not just the steady turn, but also that it was speeding up and slowing down during the turn. How about a valve stem on a car's tire? As the car is going down the road at 60 mph, the tire rotates at a constant speed but the valve stem comes to a complete stop when it's at the bottom of the wheel, and then rapidly accelerates to almost 120 mph when it is at the top of the wheel. Going from 0 to 120 to 0 again with each rotation of the wheel is quite an acceleration/deceleration. A skydiver flying in circles in a strong breeze is just like the valve stem on the car. Speeding up and slowing down with each turn. --It's all been said before, no sense repeating it here. Quote Share this post Link to post Share on other sites
sacex250 0 #77 June 11, 2011 Quoteow try the same thing just above a point on a cloudbank and you will notice that your turns are perfectly circular, with the same bank angle held throughout. How can this be, if the winds are the same as in the first case? Because the clouds are moving with you. No, the turns won't be perfectly circular, they will only look perfectly circular from your vantage point. Your ground track will look like something made with Spirograph. Let's say the clouds are moving at 20 knots, and you are orbiting above them with 20kts of airspeed. On the downwind leg, your groundspeed is 40kts, but on the upwind leg, you come to a complete stop hovering in the air while the clouds go by you at 20 kts. It looks like you're flying past them, put you're really stopped in mid-air while they go by you. Then as you turn downwind, your parachute (flying at 20kts airspeed) accelerates from 0 to 40kts in the turn until you're outracing the clouds; they're travelling at 20kts, you're doing 40kts. Then you turn upwind again and come to a complete stop while the clouds pass you by again. Your airspeed may be constant, but you are physically accelerating and decelerating each time you fly around the circle. That is a real force that you and your parachute will feel, it doesn't matter whether you're hanging in mid-air or riding in a car. --It's all been said before, no sense repeating it here. Quote Share this post Link to post Share on other sites
Martini 0 #78 June 11, 2011 Trying not to be harsh here but you are incorrect on virtually every point. This subject has been discussed for years, many apparently bright people, pilots included, never get it. If you were right I would have either stalled and fallen from the sky or had my wings torn off long ago. And I have flown wingsuits and ramair canopies in airmasses relative to the ground ("wind") of over 65 mph. Make some skydives, fly a paraglider/hang glider or a powered aircraft, then reconsider the difference between groundspeed and airspeed. It took me some time to really wrap my head around this subject when I started jumping.Sometimes you eat the bear.............. Quote Share this post Link to post Share on other sites
DaVinciflies 0 #79 June 11, 2011 QuoteHow about a valve stem on a car's tire? As the car is going down the road at 60 mph, the tire rotates at a constant speed but the valve stem comes to a complete stop when it's at the bottom of the wheel, and then rapidly accelerates to almost 120 mph when it is at the top of the wheel. -- You are so far out of your depth. The example above has nothing to do with what we are talking about as far as I can see, but you are still wrong. The valve stem momentarily has a zero vertical vector to its velocity, but it continues to have a positive velocity due to it's horizontal component, which coincidentally is maximum right at the point where you say it is zero. Not that this has anything to do with the discussion. As for the Top Gun Goldfish - NFI (no fuckin' idea). Quote Share this post Link to post Share on other sites
sacex250 0 #80 June 11, 2011 QuoteThe valve stem momentarily has a zero vertical vector to its velocity, but it continues to have a positive velocity due to it's horizontal component, which coincidentally is maximum right at the point where you say it is zero. Not that this has anything to do with the discussion. Oh please, do you really not understand that the part of the tire that is in contact with the road has to come to a complete stop each revolution and the top of the tire is moving twice as fast as the car is? If the car is going 60 mph, the bottom of the tire that's going the same speed as the ground is physically stopped and the top of the tire is moving forward at 120 mph. QuoteAs for the Top Gun Goldfish - NFI (no fuckin' idea). What a brilliant idea, if you can't feel motion if your inside a different medium, let's fill the cockpit of a fighter jet with water, give the pilot some SCUBA gear, and that way he won't feel the G-forces. Brilliant! The goldfish, the pilot, or a skydiver will feel a force of acceleration if there is a change in speed or direction no matter what medium he, or it, happens to be in. --It's all been said before, no sense repeating it here. Quote Share this post Link to post Share on other sites
sacex250 0 #81 June 11, 2011 QuoteTrying not to be harsh here but you are incorrect on virtually every point. This subject has been discussed for years, many apparently bright people, pilots included, never get it. If you were right I would have either stalled and fallen from the sky or had my wings torn off long ago. And I have flown wingsuits and ramair canopies in airmasses relative to the ground ("wind") of over 65 mph. Make some skydives, fly a paraglider/hang glider or a powered aircraft, then reconsider the difference between groundspeed and airspeed. It took me some time to really wrap my head around this subject when I started jumping. My original point was about airplanes, skydivers don't have enough mass for it to become a factor, so you're probably safe. --It's all been said before, no sense repeating it here. Quote Share this post Link to post Share on other sites
sacex250 0 #82 June 11, 2011 Ouch, this is going to hurt! I WAS WRONG! My apologies to: Zlew davelepka pchapman strop45 DaVinciflies rehmwa Martini Remster and billvon Crap, what a list! I remember when I was taking my original flying lessons 20 years ago, and our flight school had a poster on the wall with the 10 rules for cadet airman from 1920 or something. One of the rules was a warning about the downwind turn. I laughed and told my instructor that was funny, and he glared at me and said, "No, that's true." I said, "Uh uh, the airplane's flying with the wind it doesn't matter." He then proceeded to explain to me how I was wrong until I believed him. Like I said, "quality of instruction." So, pretty much everything I said was wrong. That is all. -- It's all been said before, no sense repeating it here. Quote Share this post Link to post Share on other sites
Martini 0 #83 June 11, 2011 Well, downwind turns near the ground have caused many accidents. Either the pilot approaches an object more quickly than anticipated due to combined airspeed & windspeed or the pilot mistakes high groundspeed for high airspeed and throttles back into a stall. Happens to powered and unpowered aircraft. It's a good thing boats can't stall and sink. Sometimes you eat the bear.............. Quote Share this post Link to post Share on other sites
DaVinciflies 0 #84 June 11, 2011 Glad you get it - and well done for manning up and saying so in public. No harm done! Quote Share this post Link to post Share on other sites
skybytch 259 #85 June 11, 2011 QuoteHave an actual standard to hold instructor candidates too? Have an apprenticeship format? Have a method to weed out the non hackers, after the fact? Nah, might cut into DZO's bottom line if they had to pay for quality instructors. Are dz's making bank off of the currently available canopy control courses? If so, you've got a point. For Dave - Because some people will abuse a program does not make creating that program a bad idea. We don't eliminate the speed limit because most people speed, do we? An "official", comprehensive syllabus and a piece of paper that says a person spent a certain amount of time with a real expert (assuming, of course, that said experts would be willing to serve as canopy I/E's) would help to standardize the information that is being put out there. It would encourage more people who are passionate about canopy flight to help make the sky at their home dz safer by passing that knowledge along, while giving the canopy "student" some assurance that the "coach" knows something about canopy flight. Quote Share this post Link to post Share on other sites
iowa 0 #86 June 11, 2011 Dude, This is the funniest thread I've ever read. I'm guessing you were just having fun with this. If so, well played. If not, wow! I want to know what's happening when I'm doing a flat turn above said cloud when I'm going crosswind. Still laughing. Keith ''Always do sober what you said you would do drunk. That will teach you to keep your mouth shut.'' - Ernest Hemingway Quote Share this post Link to post Share on other sites
diablopilot 2 #87 June 11, 2011 More speaking to my point that there shouldn't be a NEED for a specific canopy control course. Seems that it's becoming accepted that it's something you learn AFTER you get a license, and in THAT lies the problem. The ability to fly a parachute safely is not an OPTIONAL part of getting an "A" license. If people can't hack it, they need to not be licensed. If instructors can't teach it, then they need NOT to be instructors. Apprentice under the direct oversight of an experience instructor maybe, but not with the ability to create the next generation of skydiver.---------------------------------------------- You're not as good as you think you are. Seriously. Quote Share this post Link to post Share on other sites
jakee 1,255 #88 June 12, 2011 QuoteSo, pretty much everything I said was wrong. That is all. Well done for manning up and admitting it. Just curious, do you realise why you were wrong (about the physics and the real world effects) and what made you see it?Do you want to have an ideagasm? Quote Share this post Link to post Share on other sites
sacex250 0 #89 June 12, 2011 1) As I explained, I used to have it right until a flight instructor convinced me I was wrong. 2) http://www.aeroexperiments.org/downwindmyth.shtml Specifically, the "Brain Teasers" link near the bottom. And, quite a few other sites.It's all been said before, no sense repeating it here. Quote Share this post Link to post Share on other sites
jakee 1,255 #90 June 12, 2011 Quote1) As I explained, I used to have it right until a flight instructor convinced me I was wrong. No, I didn't mean where did you learn it, I meant do you know where the errors in your basic physics and real world reasoning were?Do you want to have an ideagasm? Quote Share this post Link to post Share on other sites
sacex250 0 #91 June 12, 2011 Put the salt down before I pepper spray ya! -- It's all been said before, no sense repeating it here. Quote Share this post Link to post Share on other sites
