KrisFlyZ 0 #1 May 3, 2006 Formulas are used from this page and others on the Dr.Math forums. http://williams.best.vwh.net/avform.htm http://williams.best.vwh.net/gccalc.htm The wingsuit used for this flight is a Prodigy. The GPS unit is an Edge 305. Other threads of interest yuri_base's thread on how to calculate true L/D on a balloon jump. Costyns thread on how to overlay GPS data on a video. Nice features ============= The edge can be configured to stop recording when the speed falls below a (user selectable) preset. The recording stops when the canopy is open. Bugs ============= 1) Due to the mounting point of the barometric altimeter being at the back of the helmet, there are errors in the altitude reading at some points. The altitude increases at certain points. However, the reading goes back to the correct number once the barometer(head) is in the correct orientation. These points are evident where an altitude gain is shown(in the excel spreadsheet). Weather ========== Upper winds on 30th April 2006 at Headcorn were 30 knots from 320. I have applied this correction and recalculated L/D on the two segments of interest. The interesting thing is that average L/D for the segments of interest( Rows 14-39, 26 secs) while flying upwind is 1.059 and 2.19(Rows 62 thru 91, 30 sec segment) while flying downwind but the corrected L/Ds are much closer for these segments (1.67 and 1.64). The attached picture is a (MB Gravity corrected...altitude is removed) map overlay from motionbased.com. For a rough comparision of calculated bearing to actual. Motionbased actually pulls weather data and can give wind speed and bearing, this is for ground winds only. There is roughly a 60 mph jump in ground speed after the turn. Please feel free to find any inconsistencies with the calculations, etc. Kris. Quote Share this post Link to post Share on other sites
yuri_base 1 #2 May 3, 2006 Kris, An interesting analysis and a drastic example that GPS data is useless until you take wind into account ("average L/D while flying upwind is 1.059 and 2.19 while flying downwind but the corrected L/Ds are much closer (1.67 and 1.64)"). A couple of notes: 1. I see a problem with your calculation: when correcting for the wind, you only correct for the component of the wind parallel to flight path (column X = column S + column Q, or Airspeed = Groundspeed + Windspeed * Cos(Angle)). The other component (Windspeed * Sin(Angle)) should also be taken into account. It's a vector sum: Airspeed = Groundspeed - Windspeed. However, since in your case the wind-to-flight angle is close to either 0 or 180, the error is small. 2. Altitude data is very noisy. Barometric GPS was not designed for freefall. I jumped from balloon with Vista C mounted on a side of the helmet and it appears from data that I jumped up 100ft in the first two seconds. Perhaps, combining horizontal data from GPS with vertical data from ProTrack will give a smoother profile. I'm also thinking about enclosing GPS in some kind of foam case so that the dynamic pressure on different sides is averaged. YuriAndroid+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio Quote Share this post Link to post Share on other sites
LouDiamond 1 #3 May 3, 2006 I quickly looked at your data but one thing I didn't readily see was how you are figuring for the winds at the varying altitudes and how they affected the entire flight. Winds can be as much as 180 degrees out from altitude to altitude which obviously has an effect on the flight data. To give you a general idea of what I am talking about and how to calculate for it along the different legs of the flight and by altitude check out This link and this link When you take that into consideration, you can see how it can get very complicated when trying to figure exactely for winds. Editted to correct link info"It's just skydiving..additional drama is not required" Some people dream about flying, I live my dream SKYMONKEY PUBLISHING Quote Share this post Link to post Share on other sites
KrisFlyZ 0 #4 May 3, 2006 No calculations were used to figure out the wind speed . It is a known, the wind data is from the airport located at the DZ. It must be the name I used for the image files. Kris. Quote Share this post Link to post Share on other sites
LouDiamond 1 #5 May 3, 2006 QuoteNo calculations were used to figure out the wind speed . It is a known, Did you look at the links I provided? It's apparent that you would HAVE to know the wind data in order to use the calculations given. When I said "figure" I was refering to how the winds affected the flight and the subsequent data."It's just skydiving..additional drama is not required" Some people dream about flying, I live my dream SKYMONKEY PUBLISHING Quote Share this post Link to post Share on other sites
KrisFlyZ 0 #6 May 4, 2006 I have attached a different version of the spreadsheet. Just correcting an error with not converting angles to radians(this was an issue in some columns only). Scott, Please illustrate the application of the formulae ( presented in the in the links that you have provided) to the data in the spreadsheet. That would be an interesting read. Kris. Quote Share this post Link to post Share on other sites
LouDiamond 1 #7 May 7, 2006 QuotePlease illustrate the application of the formulae My original question was in reference to how you figured for the affects of wind direction and speed from exit to opening on the data you collected. The links show a method used with canopies for determining that affect. Plug your wind data from that day into the portion refering to winds/direction to get a rough idea of how the winds affected your drift and influenced the data collected if you haven't already figured for it in your spread sheet."It's just skydiving..additional drama is not required" Some people dream about flying, I live my dream SKYMONKEY PUBLISHING Quote Share this post Link to post Share on other sites
yuri_base 1 #8 May 8, 2006 QuoteJust correcting an error with not converting angles to radians Bah, I made the same error, which resulted in noisy horizontal speed data. Now horizontal speed is smooth.Android+Wear/iOS/Windows apps: L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP iOS only: L/D Magic Windows only: WS Studio Quote Share this post Link to post Share on other sites
KrisFlyZ 0 #9 May 8, 2006 We are on the same page. More than one way to skin a cat Since the exit was out of an airplane and the initial speed was already around 80 mph....the glide needs a big downward adjustment to reflect an L/D number that is closer to the truth. I have done some calcs in the attached sheet for a still air exit but the s^&t is getting really deep now . Trying to improve the number(Column AG39) given by this method can be used as a training strategy when jumping from airplanes when other methods are not available. Kris. Quote Share this post Link to post Share on other sites
