shah269 0 #1 August 19, 2009 Very dumb question. Is there an equation that dictates forward velocity of a pilot and rig given zero wind conditions? For example if I weigh 180lbs and I’m on a 260 canopy what would my forward speed be with zero inputs?Life through good thoughts, good words, and good deeds is necessary to ensure happiness and to keep chaos at bay. The only thing that falls from the sky is birdshit and fools! Quote Share this post Link to post Share on other sites
airtwardo 7 #2 August 19, 2009 Too many variables involved... What 'kind' of 260-7 or 9 cell, type of wing design, type of material, lines, pilot chute...whether it's open or still packed & on yer back. ~ If you choke a Smurf, what color does it turn? ~ Quote Share this post Link to post Share on other sites
skydude2000 3 #3 August 19, 2009 The only equation I can think of that would enable you to calculate that is the pythagorean theorem. A2+B2=C2. So height(2) + glide(2) or slope = Ground distance. I have no idea how you'd calculate the actual forward speed. Oh wait!! yes I do. Buy a digital Blue ones. PULL!! or DIE!! Quote Share this post Link to post Share on other sites
shah269 0 #4 August 19, 2009 Quote What 'kind' of 260-7 or 9 cell, type of wing design, type of material, lines, pilot chute...whether it's open or still packed & on yer back. OK let's say 9 cell 260 student rig. And hopefully open and fully inflated at an altitude of say 1k ft. I woul ask what the decent rate would be but maybe that would be too much. I'm just trying to figure out what the landing speed would be.Life through good thoughts, good words, and good deeds is necessary to ensure happiness and to keep chaos at bay. The only thing that falls from the sky is birdshit and fools! Quote Share this post Link to post Share on other sites
SethInMI 174 #5 August 19, 2009 I think someone could give you a good estimate, at least knowing if it was a 7 or 9 cell, but an exact number would not be easy. I think the canopy manufacturers probably have canopy flight data, but I have never seen a good collection posted here. I would love to see a big table with glide ratios and airspeeds for a range of canopies at a range of wingloadings (0.5,1.0,1.5,2.0) and control inputs (full flight, half brakes, deep brakes, etc). But a pipe dream it will remain I am afraid.It's flare not flair, brakes not breaks, bridle not bridal, "could NOT care less" not "could care less". Quote Share this post Link to post Share on other sites
skydude2000 3 #6 August 19, 2009 You couldn't even consider the landing speed with that because the flare should change the forward speed of the canopy on landing. Maybe if you have a cop buddy with a radar gun, he could point it at you on landing. That's the only other way I can think of.PULL!! or DIE!! Quote Share this post Link to post Share on other sites
brettski74 0 #7 August 19, 2009 QuoteOK let's say 9 cell 260 student rig. And hopefully open and fully inflated at an altitude of say 1k ft. I woul ask what the decent rate would be but maybe that would be too much. I'm just trying to figure out what the landing speed would be. How big is the pilot? What is he/she wearing? You said no inputs, so I won't ask about his/her body position. What's the elevation of the landing area? What is the temperature and humidity? And about the canopy, I still don't know enough about the canopy. What fabric is it? What model is it? In what condition is the fabric? In case it's not clear to you yet, you're not going to find an answer here. All other things being equal, a smaller canopy should be faster than a larger canopy and a 9-cell is usually quicker than a 7-cell, but there are far too many variables that will affect the forward speed of a canopy in flight for there to be any single useful equation to calculate the forward speed of a canopy in flight. If you're really keen to get a number, I'd suggest finding someone with a radar or using a GPS - assuming that you have a reasonably accurate measure of the ground winds at the time. Descent rate can be measured with a GPS or a digital altimeter. Bear in mind that even then, those values will still vary depending on all of the non-canopy related factors mentioned above, including temperature, altitude, clothing, humidity and body position. Quote Share this post Link to post Share on other sites
shah269 0 #8 August 19, 2009 Quote I would love to see a big table with glide ratios and airspeeds for a range of canopies at a range of wingloadings (0.5,1.0,1.5,2.0) and control inputs (full flight, half brakes, deep brakes, etc). But a pipe dream it will remain I am afraid. BINGO! That's what I was looking for! Oh well....it was actually a work related question that segwayed its way into skydiving. Oh well....Life through good thoughts, good words, and good deeds is necessary to ensure happiness and to keep chaos at bay. The only thing that falls from the sky is birdshit and fools! Quote Share this post Link to post Share on other sites
antonija 0 #9 August 20, 2009 Get a GPS logger (good one) and start jumping different sized canopies and different models. You'd probably want at least 5-6 jumps per canopy to get good statistics and you also need a very accurate method of measuring wind speed and direction at different heights. After that it's just a couple of excel functions (or your favourite statistical software) and you have your answer!!I understand the need for conformity. Without a concise set of rules to follow we would probably all have to resort to common sense. -David Thorne Quote Share this post Link to post Share on other sites
StefB 0 #10 August 20, 2009 QuoteQuote I would love to see a big table with glide ratios and airspeeds for a range of canopies at a range of wingloadings (0.5,1.0,1.5,2.0) and control inputs (full flight, half brakes, deep brakes, etc). But a pipe dream it will remain I am afraid. BINGO! That's what I was looking for! Oh well....it was actually a work related question that segwayed its way into skydiving. Oh well.... Some people in Germany use a new/prototype measurement system called "Kate" in order to get such data. There are test reports for Pilot 150 and Spectre 150 already, but they are written in german and need translation. The testers are looking now for financial support and feedback from the community. Maybe more canopies are tested soon and/or manufacturers show some interest. http://www.dfv.aero/index.php/sicherheit%26nbsp%3B%26%26nbsp%3Btechnik/Tests Quote Share this post Link to post Share on other sites
SethInMI 174 #11 August 20, 2009 Quote Some people in Germany use a new/prototype measurement system called "Kate" in order to get such data. http://www.dfv.aero/index.php/sicherheit%26nbsp%3B%26%26nbsp%3Btechnik/Tests Very cool. I can't read German, but the tables were all in English for some reason, so I could get the gist of it. I would love to know more about Kate and I hope they get some more testing in (rear risers, deep brakes, more canopies, etc). Thanks for pointing that out! SethIt's flare not flair, brakes not breaks, bridle not bridal, "could NOT care less" not "could care less". Quote Share this post Link to post Share on other sites
popsjumper 2 #12 August 20, 2009 QuoteOh well....it was actually a work related question that segwayed its way into skydiving. Oh well.... WooooHooo! Segway is now a verb!My reality and yours are quite different. I think we're all Bozos on this bus. Falcon5232, SCS8170, SCSA353, POPS9398, DS239 Quote Share this post Link to post Share on other sites
shah269 0 #13 August 20, 2009 Quote WooooHooo! Segway is now a verb! You like that! Seems like such a simple question doesn't it? Given a mass of X under a canopy Y your forward speed should be Z and your fall rate should be A.Life through good thoughts, good words, and good deeds is necessary to ensure happiness and to keep chaos at bay. The only thing that falls from the sky is birdshit and fools! Quote Share this post Link to post Share on other sites
dorbie 0 #14 August 21, 2009 It is specific to the canopy design, trim & loading. Quote Share this post Link to post Share on other sites
shropshire 0 #15 August 21, 2009 QuoteYou couldn't even consider the landing speed with that because the flare should change the forward speed of the canopy on landing. Maybe if you have a cop buddy with a radar gun, he could point it at you on landing. That's the only other way I can think of. Or just carry a GPS unit (.)Y(.) Chivalry is not dead; it only sleeps for want of work to do. - Jerome K Jerome Quote Share this post Link to post Share on other sites
shah269 0 #16 August 21, 2009 QuoteIt is specific to the canopy design, trim & loading. Like I said, 0 trim with say a 180lb ball of mass in a zero wind condition. What would the forward steady state velocity be and the decent rate.Life through good thoughts, good words, and good deeds is necessary to ensure happiness and to keep chaos at bay. The only thing that falls from the sky is birdshit and fools! Quote Share this post Link to post Share on other sites
shropshire 0 #17 August 21, 2009 Also note that the 3 Hs come into play too. Heat, Height Humidity (of the air mass) ... all affect the flying characteristics of a canopy (.)Y(.) Chivalry is not dead; it only sleeps for want of work to do. - Jerome K Jerome Quote Share this post Link to post Share on other sites
shah269 0 #18 August 21, 2009 So you guys are telling me that there is no baseline? 180lbs of mass under a standard 260 at a height of 1kft with standard humidity and heat....... Scary!Life through good thoughts, good words, and good deeds is necessary to ensure happiness and to keep chaos at bay. The only thing that falls from the sky is birdshit and fools! Quote Share this post Link to post Share on other sites
shropshire 0 #19 August 21, 2009 Nope, I'm not saying that ... I'm saying that I don't know the answer but could work it out in practise with my little trusty GPS. (.)Y(.) Chivalry is not dead; it only sleeps for want of work to do. - Jerome K Jerome Quote Share this post Link to post Share on other sites
shah269 0 #20 August 21, 2009 Oh ok well that's cool. But you would think the manufactures would have this kind of data.Life through good thoughts, good words, and good deeds is necessary to ensure happiness and to keep chaos at bay. The only thing that falls from the sky is birdshit and fools! Quote Share this post Link to post Share on other sites
billvon 3,111 #21 August 21, 2009 >But you would think the manufactures would have this kind of data. They might, but it would likely cause more confusion than it would benefit anyone. Any canopy's performance is going to vary with: -line trim (specifically brake trim which the mfr does not control) -line age (spectra shrinks with age) -fabric age (it becomes porous) -canopy color on older canopies (some fabric colors become more porous more rapidly) -altitude -humidity -temperature -size of the jumper -loading (and a 1:1 loading on a 120 is nothing like a 1:1 loading on a 210) -riser length -chest strap geometry -type of pilot chute -what the jumper is wearing (a guy landing with a wingsuit is going to see different performance than a 4-way competitor) so it's going to be very hard to determine that canopy X is faster than canopy Y, or even what canopy X's speed _is._ Now, if you wanted, you could come up with a calibrated load - say an instrumented RPV with standard risers - and drop that, and calibrate out humidity, temperature and pressure, and get some standardized numbers. But that's a lot of work, and most manufacturers seem to prefer to spend their time on designing new canopies and testing them with regular jumpers. But if you need a project for the winter . . . Quote Share this post Link to post Share on other sites
Heatmiser 0 #22 August 21, 2009 The problem is there is no "standard 260". Make of the canopy, wear on the canopy, even within one make and model it varies some because of manufacturing tolerances. There are a whole host of different brands of "student" canopies, and they will have slightly different flight characteristics. I have test jumped a couple of the same model and size of F111 student canopies at my DZ, one was descending at 13 ft per second, and the other (much more ragged out) descended at 16. So, you could create a formula but it would only be specific for that parachute. Now, if you want a ballpark, figure this: Decending at 14 feet per second, with a glide ratio of 1.2, or 1.3. That gives you a forward speed of 18.2 feet per second(at 1.3), or 12.4 miles an hour. Oh, and I suck at math, so one of you brains here straighten me out, because that seems a bit slow. Maybe the glide ratio is higher. What you say is reflective of your knowledge...HOW ya say it is reflective of your experience. Airtwardo Someone's going to be spanked! Hopefully, it will be me. Skymama Quote Share this post Link to post Share on other sites
shah269 0 #23 August 21, 2009 So, you could create a formula but it would only be specific for that parachute. Now, if you want a ballpark, figure this: Decending at 14 feet per second, with a glide ratio of 1.2, or 1.3. That gives you a forward speed of 18.2 feet per second(at 1.3), or 12.4 miles an hour. AH HA! THANK YOU!Life through good thoughts, good words, and good deeds is necessary to ensure happiness and to keep chaos at bay. The only thing that falls from the sky is birdshit and fools! Quote Share this post Link to post Share on other sites
BDashe 0 #24 August 21, 2009 Quote if I weigh 180lbs and I’m on a 260 canopy what would my forward speed be with zero inputs? Slow. So there I was... Making friends and playing nice since 1983 Quote Share this post Link to post Share on other sites
d123 4 #25 August 21, 2009 There's no real need for that formula in the world we live. It doesn't help you much. Even if you have the speed how would you use it? Let's say the forward speed in deep brakes is X. This number can't give you any real informations at all. At the end of the flare, which is a dynamic process, the forward speed is different than X. In the process of flare, depending on how you flare the canopy (stages, time spend in each stage and in between), you'll have different speeds (the AoA and the WL will increase diferently in diferent flare types). Even if you find the number X for forward speed at the end of the flare it only going to tell that is within your running speed. We all know this because we land parachutes in nowind, crosswind or downwind (hehehehe). However, starting running from a confortable harness is not that confortable, in the begining. Esspecially when your body is tilted backward by the canopy moving back at a higher AoA. Let's go on the other side and lets say that X is higher than your running speed. What then? ) Let's say we have the forward speed at full glide. This speed changes with altitude and realistically speaking it will not help you because you have no way of knowing or predicting how the winds are doing at different altitudes and in different times of the day. You know why we all hate the meteo guy? Because at the heart of it, predicting the weather is not easy at all. If skydiving would have been predictible by numbers, it would have been not interresting at all. Imagine coorporate outdoor activities. They are safe but not fun on the personal levelbecause you go in a fun (as a buzzword) pipeline that is not that fun at all. Life has randomness and mistakes at the heart of it. There are other ways to predict life but that's not via numbers. It's called experience. To get experience you'll have to experience the ride and not the numbers Did I mention that the greatest things in life comes from mistakes? Think wine, cheese, wife, beautifull wild kids ... and those mistakes combine really well together. Sometimes I think that Life is a perfect mistake that keeps on making perfect mistakes. Lock, Dock and Two Smoking Barrelrolls! Quote Share this post Link to post Share on other sites