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Dwain · September 26th, 2002

> Dwain's numbers (around 2.6) of glide ratio for
> Fox and Mojo seems slightly high, if we consider
> that PD gives for a Sabre a glide ratio of 2.7

I totally agree that the numbers I gave seem slightly high and I was somewhat surprised at these numbers when I downloaded and averaged them. The figures I gave were not supposed to be attributed with any sort of accuracy, but simply the average value of what I had obtained from a small number of jumps.

My figures came from only 5 jumps on Vtec FOX's (245 and 205) and 3 jumps on Mojo's (280 and 220) by three different jumpers so this isn't even close to being a large enough sample size. The one thing I did noticed however was that differences in wing loading didn't create significant variances in glide ratio to the extent that has been theorized by some people.

All flights were from BASE jumps and involed a straight line of flight descending about 350 feet (so this distance is small enough for GPS inaccuracies to effect the figures as well). On the jumps I personally did I was working the canopies to get the best glide possible (combination of rear riser and very light toggle input).
All jumps were from the same object in what I perceived to be nil wind at the time (nothing at exit, and nothing at landing). However I can't guarantee that no wind was blowing during the mid point of flight (weird wind conditions are known to exist at this object). I do suspect that there may have been a slight tail wind push on some of those jumps (the only clue I have is that these figures seem a touch too high). In retrospect I should have had the pilots drop a streamer during flight and had someone on the ground observe it. It the streamer was seen to drift then I would have discarded the GPS data for that flight.

While BASE #689 averaged a glide of 2.2 when flying both into and with the wind, wind speeds can vary at different altitudes so this figure (like mine) is only indicative in nature. The only way to get more accurate figures is to obtain a much, much large data pool.

In regards to the term glide ratio I was referring to the best possible glide attainable on a particular brand of canopy in nil wind. The fact that there are variables that will create differences in glide ratio is obvious.

However the fact that some brands of canopies out glide others (eg. Blackjack vs Mojo) becomes very obvious when you've done just a handful of jumps on both of them, without a need for detailed scientific data.

September 26th, 2002	#13 (permalink)
Dwain BASE Forum Guru Join Date: Dec 1969 Location: . Posts: 116 Rating: 0% (0)	RE: Glide Ratio > Dwain's numbers (around 2.6) of glide ratio for > Fox and Mojo seems slightly high, if we consider > that PD gives for a Sabre a glide ratio of 2.7 I totally agree that the numbers I gave seem slightly high and I was somewhat surprised at these numbers when I downloaded and averaged them. The figures I gave were not supposed to be attributed with any sort of accuracy, but simply the average value of what I had obtained from a small number of jumps. My figures came from only 5 jumps on Vtec FOX's (245 and 205) and 3 jumps on Mojo's (280 and 220) by three different jumpers so this isn't even close to being a large enough sample size. The one thing I did noticed however was that differences in wing loading didn't create significant variances in glide ratio to the extent that has been theorized by some people. All flights were from BASE jumps and involed a straight line of flight descending about 350 feet (so this distance is small enough for GPS inaccuracies to effect the figures as well). On the jumps I personally did I was working the canopies to get the best glide possible (combination of rear riser and very light toggle input). All jumps were from the same object in what I perceived to be nil wind at the time (nothing at exit, and nothing at landing). However I can't guarantee that no wind was blowing during the mid point of flight (weird wind conditions are known to exist at this object). I do suspect that there may have been a slight tail wind push on some of those jumps (the only clue I have is that these figures seem a touch too high). In retrospect I should have had the pilots drop a streamer during flight and had someone on the ground observe it. It the streamer was seen to drift then I would have discarded the GPS data for that flight. While BASE #689 averaged a glide of 2.2 when flying both into and with the wind, wind speeds can vary at different altitudes so this figure (like mine) is only indicative in nature. The only way to get more accurate figures is to obtain a much, much large data pool. In regards to the term glide ratio I was referring to the best possible glide attainable on a particular brand of canopy in nil wind. The fact that there are variables that will create differences in glide ratio is obvious. However the fact that some brands of canopies out glide others (eg. Blackjack vs Mojo) becomes very obvious when you've done just a handful of jumps on both of them, without a need for detailed scientific data.