dsbbreck 0 #51 November 22, 2003 QuoteWhy would it submerge faster? For the same reason your canopy dives faster in a hook turn in high winds. Haven't you been listening? LOL. QuoteWhat causes a submarine to submerge? All that steel is fucking heavy. Without the air in the ballast it's going to sink. Duh! QuoteWould it submerge faster if it was doing 30 knots through calm water or 0 knots into a 30 knot current? Good question, know anybody that has a submarine? Let's go test this theory.David "Socrates wasn't killed because he had the answer.......he was killed because he asked the question." Quote Share this post Link to post Share on other sites
Hooknswoop 19 #52 November 22, 2003 QuoteDoes snow fall slower if the wind is blowing? A snowflake is symetrical and doesn't have the rectangular shape needed to change reletive to the wind in order to increase or decrease speed. Exactly. A canopy's shape doesn't change because of the wind. It has the same descent rate, regardless of the wind. QuoteDoes a submarine rise faster if there is a current or not? (all other things being equal) I believe it does, but I guess we'd need to ask a submarine pilot I'm not a submarine pilot, but I have 500+ hours underwater. It doesn't. QuoteCan a bird descend or climb faster if there is wind? (no up-drafts/downdratfs) I believe it can, but once again, we need to ask a bird. Not likely that it will answer, but if it does, why? QuoteDoes an aircraft descend or climb faster if there is wind? Most defenatly, this is proven every weekend when we climb over the mountains to use the wind coming off the mountains to create more lift. Updrafts, yes. Wind, no. Wind does not create lift. A glider with a 60 mph foward speed flying into a 60 mph headwind cannot hover. It will descend at the same rate as if there was zero wind. A glider needs updrafet/thermals to climb or sustain altitude without trading airspeed. QuoteA raft anagoly doesn't work well because it isn't completely submerged in the medium, it is partially in one medium and partially in another. You can't honestly believe that the low aspect of the raft can be affected that greatly by wind or any other force. The water is the biggest factor. Yes, the water is the largest force, but depending on strength of the wind, it cannot be discounted. QuoteIf you swim underwater at a 90-degree abngle across a stream, it takes the same amount of time to reach the other side regardless if there is a current or not. If there is a current, you just end up on the other side of the stream down stream instead of directly across from where you started. The current accounts for the added distance covered over the stream bed. True, but change to a 45 degree angle and you'll get there quicker in a current. No, you won't. Your groundspeed would be higher, but you wouldn't reach the other side any quicker than with zero current. Do the math. QuoteIf you point a Pilatus Porter straight down, 90-degrees to the ground in zero wind and a steady 30 mph wind, it will have the exact same descent rate. The difference will be it's ground track. In a straight down dive in zero wind, the Porter will have a ground track across the ground in the direction of the top of the wing. If there is wind, and the top of the wing is on the up-wind side, the wind will cancel out the aircraft's ground track, but the descent will be the same. If it rolls 180- degrees, it's ground track will be whatever it would be in no wind plus 30 mph. Agreed, because it doesn't have the angle needed to use the wind to create a faster decent rate. Put it at a 45 degree angle instead of straight down and it will have a greater decent rate. No, it won't. Ask any pilot, including me. Wind does not affect the descent rate of an aircraft. QuoteTo justify both of the swimmer and porter arguments, you'd have to compare them to flying your canopy straight to the ground. Which, if you were doing that, I would agree that the wind would have no affect. It's the angle to the wind that created more speed. More speed, more ground speed (or less or no efecct at all depending on the direction of the sircraft and wind), no more airspeed or descent rate. Derek Quote Share this post Link to post Share on other sites
dsbbreck 0 #53 November 22, 2003 -------------------------------------------------------------------------------- Quote -------------------------------------------------------------------------------- Would it submerge faster if it was doing 30 knots through calm water or 0 knots into a 30 knot current? -------------------------------------------------------------------------------- Good question, know anybody that has a submarine? Let's go test this theory. After thinking about this for a moment, I believe they would decend at the same rate if all else was equal such as the dive angle. The only difference would be the location they ended up.David "Socrates wasn't killed because he had the answer.......he was killed because he asked the question." Quote Share this post Link to post Share on other sites
dsbbreck 0 #54 November 22, 2003 -------------------------------------------------------------------------------- Quote -------------------------------------------------------------------------------- Does an aircraft descend or climb faster if there is wind? -------------------------------------------------------------------------------- If this isn't true then why do we take off into the wind.David "Socrates wasn't killed because he had the answer.......he was killed because he asked the question." Quote Share this post Link to post Share on other sites
Hooknswoop 19 #55 November 22, 2003 QuoteWhy would it submerge faster? -------------------------------------------------------------------------------- For the same reason your canopy dives faster in a hook turn in high winds. Haven't you been listening? LOL. I have been listening and you have not explained the physics or aerodynamics of your position. QuoteWhat causes a submarine to submerge? -------------------------------------------------------------------------------- All that steel is fucking heavy. Without the air in the ballast it's going to sink. Duh! Exactly, and the current has no effect on how mcuh a submarine weighs. QuoteWould it submerge faster if it was doing 30 knots through calm water or 0 knots into a 30 knot current? -------------------------------------------------------------------------------- Good question, know anybody that has a submarine? Let's go test this theory. I'll answer it for you. The same. It will submerge the same regardlessof the current. A canopy does not dive any longer or faster if there is wind or not. Why would it? Derek Quote Share this post Link to post Share on other sites
Hooknswoop 19 #56 November 22, 2003 QuoteAfter thinking about this for a moment, I believe they would decend at the same rate if all else was equal such as the dive angle. The only difference would be the location they ended up. Exactly, it makes no difference, to a submarine or to a canopy. Derek Quote Share this post Link to post Share on other sites
Hooknswoop 19 #57 November 22, 2003 QuoteDoes an aircraft descend or climb faster if there is wind? -------------------------------------------------------------------------------- If this isn't true then why do we take off into the wind. Because a head wind reduces the ground roll before reaching the airspeed required to fly. Takes less runway to take off and reduces wear on the tires. The airpseed at which an aircraft takes off at is not affected by the amount of wind. It still needs the same airspeed, but it reaches that sirpeed sooner since it starts it's ground roll with airspeed i.e. wind. Derek Quote Share this post Link to post Share on other sites
dsbbreck 0 #58 November 22, 2003 QuoteQuoteDoes snow fall slower if the wind is blowing? A snowflake is symetrical and doesn't have the rectangular shape needed to change reletive to the wind in order to increase or decrease speed. Exactly. A canopy's shape doesn't change because of the wind. It has the same descent rate, regardless of the wind. I never said a canopy changes shape in high winds, it's the unequal, airfoil shape that makes it able to use the wind to increase speed. A snowflake doesn't have that. QuoteDoes a submarine rise faster if there is a current or not? (all other things being equal) I believe it does, but I guess we'd need to ask a submarine pilot I'm not a submarine pilot, but I have 500+ hours underwater. It doesn't. 500+ hours doing what underwater. How does this give you the expertise to know whether it decends faster in a current? QuoteCan a bird descend or climb faster if there is wind? (no up-drafts/downdratfs) I believe it can, but once again, we need to ask a bird. Not likely that it will answer, but if it does, why? QuoteDoes an aircraft descend or climb faster if there is wind? Most defenatly, this is proven every weekend when we climb over the mountains to use the wind coming off the mountains to create more lift. Updrafts, yes. Wind, no. Wind does not create lift. A glider with a 60 mph foward speed flying into a 60 mph headwind cannot hover. It will descend at the same rate as if there was zero wind. A glider needs updrafet/thermals to climb or sustain altitude without trading airspeed. Wind does not create lift? What world are you living in? How does a glider, Hence no motor, have a 60 mph forward speed with a 60 mph headwind. Seems to me it would be flying backward, but it would still have lift. If wind didn't create lift, you'd never have to tie down your aircraft on the tarmac. There would be no worry of it flipping over. QuoteA raft anagoly doesn't work well because it isn't completely submerged in the medium, it is partially in one medium and partially in another. You can't honestly believe that the low aspect of the raft can be affected that greatly by wind or any other force. The water is the biggest factor. Yes, the water is the largest force, but depending on strength of the wind, it cannot be discounted. QuoteIf you swim underwater at a 90-degree abngle across a stream, it takes the same amount of time to reach the other side regardless if there is a current or not. If there is a current, you just end up on the other side of the stream down stream instead of directly across from where you started. The current accounts for the added distance covered over the stream bed. True, but change to a 45 degree angle and you'll get there quicker in a current. No, you won't. Your groundspeed would be higher, but you wouldn't reach the other side any quicker than with zero current. Do the math. I have done the math. You're just not listening QuoteIf you point a Pilatus Porter straight down, 90-degrees to the ground in zero wind and a steady 30 mph wind, it will have the exact same descent rate. The difference will be it's ground track. In a straight down dive in zero wind, the Porter will have a ground track across the ground in the direction of the top of the wing. If there is wind, and the top of the wing is on the up-wind side, the wind will cancel out the aircraft's ground track, but the descent will be the same. If it rolls 180- degrees, it's ground track will be whatever it would be in no wind plus 30 mph. Agreed, because it doesn't have the angle needed to use the wind to create a faster decent rate. Put it at a 45 degree angle instead of straight down and it will have a greater decent rate. No, it won't. Ask any pilot, including me. Wind does not affect the descent rate of an aircraft. QuoteTo justify both of the swimmer and porter arguments, you'd have to compare them to flying your canopy straight to the ground. Which, if you were doing that, I would agree that the wind would have no affect. It's the angle to the wind that created more speed. More speed, more ground speed (or less or no efecct at all depending on the direction of the sircraft and wind), no more airspeed or descent rate. DerekDavid "Socrates wasn't killed because he had the answer.......he was killed because he asked the question." Quote Share this post Link to post Share on other sites
dsbbreck 0 #59 November 22, 2003 Quote -------------------------------------------------------------------------------- After thinking about this for a moment, I believe they would decend at the same rate if all else was equal such as the dive angle. The only difference would be the location they ended up. -------------------------------------------------------------------------------- Exactly, it makes no difference, to a submarine or to a canopy. Derek You just agreed with my theory, Your saying the current speed does have an affect.David "Socrates wasn't killed because he had the answer.......he was killed because he asked the question." Quote Share this post Link to post Share on other sites
dsbbreck 0 #60 November 22, 2003 Ok, this is getting hard to follow, so let's simplify this. Hooknswoop...answer me one question. Is it true that taking off in an aircraft into a 30mph headwind would take less effort,(power, fuel, input) than taking off in 0 winds?David "Socrates wasn't killed because he had the answer.......he was killed because he asked the question." Quote Share this post Link to post Share on other sites
Hooknswoop 19 #61 November 22, 2003 QuoteOk, this is getting hard to follow, so let's simplify this. Good ideaQuoteIs it true that taking off in an aircraft into a 30mph headwind would take less effort,(power, fuel, input) than taking off in 0 winds? It gets off the ground after a shorter ground roll. It still takes the same power and input. This is because it is touching the ground and the ground plays a roll in take off distance. It still requires the same airspeed to fly and the same amount of lift. It lifts off after a shorter ground roll because the wind cancels out it’s ground speed. My turnDoes it take less power, etc for an airplane to fly over the runway (out of ground effect) at 100 knts airspeed with a 30 mph headwind, zero wind, or tail wind? I would like to cover the river/swimmer analogy. I did the math: Given: 200 foot wide river Swimmer swims at 2 mph at a 45-degree angle, downstream. 0 mph current and 20 mph current For a 0 mph current, it will take the swimmer 96.43 seconds to reach the other side, 200 feet down stream of where he started. For a 20 mph current, the swimmer will reach the other side in 96.43 seconds, 3028.29 feet downstream of where he started. Either way, same amount of time, the only difference is the ground he covers. Derek Quote Share this post Link to post Share on other sites
dsbbreck 0 #62 November 22, 2003 I'm not trying to be argumentative here, but show your math. I'm not seeing how you got this answer.David "Socrates wasn't killed because he had the answer.......he was killed because he asked the question." Quote Share this post Link to post Share on other sites
dsbbreck 0 #63 November 22, 2003 Using your swimmer analogy. Think about the angle of your swimmer swimming downstream at a 45 degree angle. This would be equivalent to your canopy in a climb going downwind, not a decent into the wind. The swimmer should be swimming up stream to have the proper angle. A swimmer swimming downstream would swim much further and it would take him longer to reach the other side because the force of the current would be pushing him back to the shore he started from. Edited to include the bold entries.David "Socrates wasn't killed because he had the answer.......he was killed because he asked the question." Quote Share this post Link to post Share on other sites
dsbbreck 0 #64 November 22, 2003 I'm not a pilot, but I do understand what you said about the take off. I disagree though that it takes the same amount of power and input to climb into the wind as it does with no wind. The same holds true for landing. I know this from landing my canopy. I don't have to give it as much input/flare to get the lift on high wind days. Are there any other pilots out there that can comment on this point.David "Socrates wasn't killed because he had the answer.......he was killed because he asked the question." Quote Share this post Link to post Share on other sites
Hooknswoop 19 #65 November 22, 2003 QuoteI disagree though that it takes the same amount of power and input to climb into the wind as it does with no wind. http://virtualskies.arc.nasa.gov/weather/youDecide/climbPreformChart.html This is a link to a climb performance chart. It does not take uinto account the winds, because they have no effect. I'm working on a diagram for my math. Derek Quote Share this post Link to post Share on other sites
grega 0 #66 November 22, 2003 The only part where the wind does effect the climb is while the plane is still touching the ground. It doesn't need as much ground speed to get in the air because it's airspeed is higher for whatever the windspeed is. Once the aircraft is off the ground, it's just the same as there would be no wind. Excluding the turbulences of course. I wish i could explain it to you with equations, but what hooknswoop is trying to do, is to explain it to you in easier way, with examples. If i show you the equations and calculations (in physics) you sure wouldn't understand even half as much as you do now. Unless you're a physics, then you should know that you don't loose more altitude in a (theoretically turbulence free) wind during a turn."George just lucky i guess!" Quote Share this post Link to post Share on other sites
Hooknswoop 19 #67 November 22, 2003 QuoteI know this from landing my canopy. I don't have to give it as much input/flare to get the lift on high wind days. From my canopy course: The initial part of the flare stops your descent, as you continue to flare, it stops your forward movement. When landing in windier conditions, the parachute’s ground speed will reach zero when the airspeed becomes equivalent to the wind speed. In other words, when landing facing a 10-mph headwind, the parachute’s airspeed needs to be slowed to 10 mph in order to create a zero ground-speed landing. You will note that your canopy can sustain flight at 10 mph for a longer period of time than it can dwell at the stall point. This will create a longer floating phenomenon at the end of the surf when landing on days with some wind and explains why you have to “flare less” on windy days. Derek Quote Share this post Link to post Share on other sites
dsbbreck 0 #68 November 22, 2003 I just want to let you know that I am willing to admit when I'm wrong once It's been proven to me......BUT I'M NOT THERE YET! If you are right and I'm wrong, make me understand. Canuck, myself, SBS, and many others have felt the phenomenon of a faster decent during a hookturn on windy days. I've almost planted myself in the ground many times because of this. It can't all just be perception. Going back to your intitial explanation to Canuck... QuoteIt's only perception. You are a pilot, think of it this way: You are in a C-172 and bring the power to idle and maintain 70 kts. That will give you a steady descent rate, somewhere near 500 fpm. It doesn't matter if you are bucking a 70 kts headwind or have a 70 kts tailwind, the 500 fpm won't be affected. Wind only affects groundspeed. This doesn't say anything about having a nose down angle like a canopy during a hook turn. Which is what I'm trying to say. And Explain this to me: Quote You will note that your canopy can sustain flight at 10 mph for a longer period of time than it can dwell at the stall point. This will create a longer floating phenomenon at the end of the surf when landing on days with some wind and explains why you have to “flare less” on windy days. You're saying wind does play an effect on your canopy in this phenomenon, so why are you so against the possibility of it playing an effect during a hook turn.David "Socrates wasn't killed because he had the answer.......he was killed because he asked the question." Quote Share this post Link to post Share on other sites
Hooknswoop 19 #69 November 22, 2003 For the 0 mph current, 200 foot wide river, swimming at a 45-degree angle: 2 mph=2.93 FPS A right triangle w/ 200 foot sides has a Hypotenuse of 282.84 feet. (a^2+b^2=c^2) At 2.93 FPS it takes 96.53 seconds to travel 282.84 feet. For the 20 mph current and swimming upstream at a 45-degree angle: Swimming upstream at 2.93 fps breaks down to a 2.07 fps vector directly across the stream. {Sine 45= opposite/2.93}= 2.07 This means the resulting vector is 27.937 fps with an angle downstream of 4.25 degrees. {29.33-2.07=27.86}{(27.86^2 + 2.07^2 = RV^2)= 27.937}{Inverse sine x = 2.07/27.937} = 4.25 degrees. So the swimmer’s actual direction over the ground is 4.25 degrees from the shoreline. His resultant speed over the ground is 27.937 fps. The distance he will actually travel is 2638.75 feet. {(sin 4.25 = 200 / TD) = 2698.75} The distance downstream he will travel is 2691.33 feet. {(DS^2 + 200^2 = 2698.75^2) = 2691.33) It will take the swimmer 96.60 seconds to travel 2838.77 feet at 29.40 fps. {(2838.77 feet/29.40 fps) = 96.56 seconds} The difference of 96.53 seconds and 96.60 (0.07 seconds) seconds is because I only took it out 2 places and rounding. Derek Quote Share this post Link to post Share on other sites
Hooknswoop 19 #70 November 22, 2003 QuoteI just want to let you know that I am willing to admit when I'm wrong once It's been proven to me......BUT I'M NOT THERE YET! Fair enoughQuoteIt's only perception. You are a pilot, think of it this way: You are in a C-172 and bring the power to idle and maintain 70 kts. That will give you a steady descent rate, somewhere near 500 fpm. It doesn't matter if you are bucking a 70 kts headwind or have a 70 kts tailwind, the 500 fpm won't be affected. Wind only affects groundspeed. -------------------------------------------------------------------------------- This doesn't say anything about having a nose down angle like a canopy during a hook turn. Which is what I'm trying to say. A C-172 would have a nose down angle in a 500 fpm descent. Put it an sustain constant 45-degree dive angle. It will descent at the same rate, regardless of the wind. Quote You will note that your canopy can sustain flight at 10 mph for a longer period of time than it can dwell at the stall point. This will create a longer floating phenomenon at the end of the surf when landing on days with some wind and explains why you have to “flare less” on windy days. You're saying wind does play an effect on your canopy in this phenomenon, so why are you so against the possibility of it playing an effect during a hook turn. It only plays a role in ground speed. It appears to float with zero airspeed, but that is only because it’s airspeed matches the wind speed. The role wind plays is to reduce it’s ground speed. You are actually landing at a higher airspeed than in no wind. If you suddenly took the wind away, you would suddenly begin moving over the ground again. Derek Quote Share this post Link to post Share on other sites
dsbbreck 0 #71 November 22, 2003 Let me see if I can simplify the perception. Because your ground speed is less in high wind but your dive angle and decent speed are the same your recovery arc seems steeper over a fixed point on the ground giving you the impression of a faster decent rate. Does that make sense?David "Socrates wasn't killed because he had the answer.......he was killed because he asked the question." Quote Share this post Link to post Share on other sites
Hooknswoop 19 #72 November 22, 2003 QuoteBecause your ground speed is less in high wind but your dive angle and decent speed are the same your recovery arc seems steeper over a fixed point on the ground giving you the impression of a faster decent rate. YesDerek Quote Share this post Link to post Share on other sites
dsbbreck 0 #73 November 22, 2003 Ok, for the purpose of this forum, I will admit I WAS WRONG..... Now.....let's get back to that swimmer...... Just kidding. It's been a fun Snowy Colorado day discussing something about skydiving. Later Hook.David "Socrates wasn't killed because he had the answer.......he was killed because he asked the question." Quote Share this post Link to post Share on other sites
Hooknswoop 19 #74 November 23, 2003 It's not about right or wrong. It is about learning.Take care and thanks for making remeber how to do geometry, it's been a while. And to be honest, I'm not sure how good my math was. Derek Quote Share this post Link to post Share on other sites
dsbbreck 0 #75 November 23, 2003 I admit, when we got into sine and tangents I gave up. My college text books are long gone.David "Socrates wasn't killed because he had the answer.......he was killed because he asked the question." Quote Share this post Link to post Share on other sites
