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mbondvegas

What are World Class Fall Rates and Flight Times Down/Up to These Dates

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The point is that even if exiting in the opposite direction of flight has a 25% effect(this is equivalent of being at the exit point going the right way, 400m lower than where you first exited...impossible if you turned immediately.) on the overall L/D, the total speed is 96 mph, still too slow.

Kris.

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Kris,

Jump was distance chasing, not speed chasing.
Robert was not slower - we were equally fast (if you ask me). :P
On max glide speed is not the fastest we can fly.
In my opinion your calculation (96 mph) fits here quite well.
I am using my calculation model for distance only. How it works for speed I don't know.

What do you think, what total speed you (should) have while flying max glide in Phantom?

Boris

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Kris,

Obviously you don't understand what I want to say.
I am using my 1.8 GR estimation for distance calculation and it works for me (the way I jump) - that is all!

I am not saying that I am actually flying 1.8 nor that my total speed is 80 mph. Probably it is better than that..

What you think your speed is while flying max glide in Phantom?

Boris

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Obviously you don't understand what I want to say.

I am not saying that I am actually flying 1.8 nor that my total speed is 80 mph. Probably it is better than that..




Let's break down the problem. The total flight time is ~92 secs(1600m vertical distance and 39 mph average speed).

a) Exit(at Point A) facing North(for the sake of clarity) at 65 knots(33.22 m/s).
b) Turn south quickly(less than 2 secs)...maximum distance traveled in the North direction is 66.44m.

c) Maximum of 10 secs is needed to cover this distance going south. A lot more than 66 m can be covered in 10 secs from a still air exit.

Using values for this, show me how the speed on the south leg could have been 96 mph (total speed along glidepath...or a reasonable number).

96 mph is too slow. If you jump with a GPS for a few jumps and see what speeds you get when flying for distance, you will see why these numbers you post are wrong.

I am almost the same height(187 cm) and was the same exit weight as you when I got this GPS data(last year).

Downward speed was mid 40s and GR was between 2.2 and 2.4. That makes the total speed range 108 - 117 mph.

Kris.

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For example take Robert's jump from Smellvegen.
Here is just straight flight from point to point.
Used height is 930 meters, covered distance is 2100 meters and total time is 50 second. Wind was close to zero as I recall.
Simple calculation will give you GR 1:2.25 and average total speed 165 km/h (102 mph) - (average speed is total path over total time).
Robert is flying V2 and I trust to him that Vampire is still faster than Phantom.

Regarding use of GPS, in my opinion people are trusting too much to the GPS numbers.
I am not convinced about precision and accuracy of GPS data.
Is there any test of precision and accuracy of GPS device in skydiving environment?

I believe more to the detailed map and stopwatch even if that makes my GR lower than what people are measuring with GPS's.
I will end further discussion here.

Regards,

Boris

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Used height is 930 meters, covered distance is 2100 meters and total time is 50 second.



Height, distance and time allow to estimate effective L/D using wingsuit equations. For Y=3100ft, X=7000ft, t=50s the result is: L/D = 3.15, equivalent sustained speeds Vx=107mph, Vy=34mph.

The simple "averaging" method (L/D ~ distance/[available altitude - altitude to start flying]) is too crude to be useful, because even if your L/D is very consistent from jump to jump, it'll give you different results for mountains of different height (lower L/D on lower ones and higher on higher ones, due to initial start eating lesser chunk of overall altitude).
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

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I am not convinced about precision and accuracy of GPS data.
Is there any test of precision and accuracy of GPS device in skydiving environment?



Boris, GPS data like anything can have its faults but for the most part it's accurate within the receivers parameters. There exists a good deal of testing/data with GPS in regards to skydiving on the military side of the house.

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Used height is 930 meters, covered distance is 2100 meters and total time is 50 second. Wind was close to zero as I recall.....I believe more to the detailed map and stopwatch even if that makes my GR lower than what people are measuring with GPS's.




I think you are right in this thinking to a degree. A GPS is a tool, like a stop watch that is only effective if used correctly. I am assuming you are using the pilots word for where he opened above to calculate the distance covered? In situations like this, a GPS can be used to definitively pinpoint where the canopy opened and give a more accurate distance covered than relying on the pilots recall or from someone on the ground looking up. Using the GPS derived distance information, continue with your simple calculation for an even more precise calculation. If you really wanted to get geeky, a streamer could be thrown from the exit point to get a better idea about winds but I am betting you're not the pocket protector type.



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Regarding use of GPS, in my opinion people are trusting too much to the GPS numbers.




I agree.What I think has happened is that some have gotten too wrapped around the axle with trying to over analyize GPS data after the fact and dare I say it (gasp) the ego factor. GPS is a tool, a very precise tool, but for some that tool is a hammer and when all you have is a hammer everything starts to look like a nail.:)
"It's just skydiving..additional drama is not required"
Some people dream about flying, I live my dream
SKYMONKEY PUBLISHING

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Could someone please explain where this distrust of GPS comes from?

In my experience, GPS is very accurate. With my Foretrex 201, it claims to maintain an accuracy of less than 3 meters on most jumps. When comparing the data to a Google Earth map, I'm consistently convinced the positioning data is as precise as claimed. For skydiving, the easiest position to compare with absolute confidence is where I landed, and GPS data displayed in Google Earth is always in agreement with my visual judgment (especially at DZs where I'm very familiar with the layout of the landing area). But even with my rudimentary spotting skills, I've become convinced the exit point is also fairly dead on.

What is more accurate, a GPS plot of your flight, or eyeballing your exit and deployment location compared to landmarks? Really how precise can you be with your eyes, suspended in air? Perhaps it's different for BASE, where the opening alt puts you much closer to the ground, but even then, I have a hard time believing VPS (visual positioning system) is superior to (or even comparable to) GPS.

Where I see a flaw in analyzing GPS data is not the GPS technology itself, but the impossible-to-nail down variable of wind. I've been advised that officially published wind data is not a reliable source since the actual winds can significantly differ. Nor is relying on the pilot's notes since that is also an imprecise art (so I've been told).

So performance numbers from GPS flights can't be taken strictly serious. Not because the GPS is imprecise, but that the numbers do not reflect the affect of the wind.

But is this any different than using equations based on VPS? How can that system be any better at compensating for wind?
Brian Drake

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Height, distance and time allow to estimate effective L/D using wingsuit equations. For Y=3100ft, X=7000ft, t=50s the result is: L/D = 3.15, equivalent sustained speeds Vx=107mph, Vy=34mph.



All looked great then my mind actually melted when I got to row 269 of 500+ and my hand started to involuntary speed slap me for even opening what I knew would be a data graph :S

Scott C.
"He who Hesitates Shall Inherit the Earth!"

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The way L/Ds have been reported on this forum(horizontal distance / vertical - 300(150 for opening and deployment).

A flight of 2100m for 930m of altitude is an L/D of 3.33(2100/630). See why 1.8 sounds too low?

From an airplane there is no altitude used in starting a flight. So the numbers from an airplane will be better if you use the method you used to calculate L/D.

Kris.
P.S: As a side note, I must say that the flight in Kjerag_07.wmv is nowhere near 2100m(you maybe talking about another flight). The 2km point(the ladder in the wire fence behind the white house...This is same fence the we climb over to access the pendulator area) is to the left and ahead of the opening frame and it is not hard to tell that the camera is mounted pointing forwards, this puts the flier behind where the opening point seems to be from the video.

As an example , if you stop the video at 1:15 the shore closest to the wall, in front of the Big rocks is 1500m compared to 1600m for the point of the nose on the other side of the river. The white house is 1900m away and the closer you come towards the wall(perpendicular to it) from the white house the distance to the exit point decreases.

I walked the landing area several times with a GPS(Hey Scott...this boosted my ego so much, I had a Hard On the entire time:P:ph34r::D).

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So performance numbers from GPS flights can't be taken strictly serious. Not because the GPS is imprecise, but that the numbers do not reflect the affect of the wind.



GPS numbers with whatever correction we can apply for wind are helpful if you can download after the jump and compare with other jumps on the same day.

For me the numbers out of the airplane matched quite well with numbers from Smellveggan jumps. I discarded the ITW data because opening altitudes were too high for GPS based altitude to be trusted(too much possible error).

I don't carry a GPS anymore on my jumps, its gotten too boring.

Kris.

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Could someone please explain where this distrust of GPS comes from?

?



GPS without WAAS does not have anything like the accuracy on altitude as it does on the other coordinates. It's a matter of geometry.
...

The only sure way to survive a canopy collision is not to have one.

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Don't most loggers that skydivers/base jumpers use have WAAS? Both my WBT-201 and Foretrex 201 do.



I've not seen "most loggers", so I can't say.

Having WAAS capability doesn't necessarily mean WAAS is enabled - my aviation GPS initializes basic GPS very quickly, but it takes a while to initialize WAAS.
...

The only sure way to survive a canopy collision is not to have one.

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bdrake wrote: Where I see a flaw in analyzing GPS data is not the GPS technology itself, but the impossible-to-nail down variable of wind.



This is partly a problem but not a deal breaker to throw the value added from analyizing GPS data entirely. While wind data obtained by most weather agencies can be relied on for general aviation and skydiving, it is always in a constant state of flux. Trying to get consistent or real time wind data is like trying to step on the same piece of water in a moving stream.

As I stated, you could throw a wind streamer from the exit point to get a general idea of winds at that moment in time and you could even have people with anonometers at the exit and expected landing point. However wind does gust without warning. The only way I have been able to get winds that I consider even remotely closer to what is actualy going on in the sky at that moment is through dropping a wind sonde right before you jump, but there is even a lag time in that as the sonde descends and transmits its data back to the aircraft. The one area that I think its justifiable and practical to use averaging is wind data. If you throw a streamer and it takes off and the next jump it barely moves away from the wall, you know there will be a drastic difference in the data the GPS will have when you download it,something to keep in mind when looking at and evaluating your performance data.


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kris wrote:I walked the landing area several times with a GPS(Hey Scott...this boosted my ego so much, I had a Hard On the entire time)



I'm glad to hear that using GPS data to figure out distances on the ground cured your ED problem.;) In all seriousness, using a GPS to more acurately determine position is what it is designed for and is only one part of a bigger equation that also has infinite variables that could effect the outcome at the end of the day when evaluating ones performance.


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kris wrote: GPS numbers with whatever correction we can apply for wind are helpful if you can download after the jump and compare with other jumps on the same day.




Therein that statement lies the simple truth to all the pointless number crunching that gets thrown out in these threads. GPS is a tool to be used as a personal yardstick to evaluate ones own performance on that given day with those given conditions. If you really wanted to longterm chart performance you would do it similar to the way competative shooters and even atheletes do by writing it all down in a log with things like date/time of day/temperature,environmental conditions, how you felt, etc. in order to see what does and doesn't work for you.


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kallend wrote: GPS without WAAS



For those who don't know it already, keep in mind that WAAS is a North American system and that most of Europe uses EGANOS and parts of Asia are using MSAS. A few other countries also have there own version of WAAS as well. Most but not all GPS receivers will display on the satellite screen if you are receiving from a WAAS corrected satellite(if you have WAAS capability).
"It's just skydiving..additional drama is not required"
Some people dream about flying, I live my dream
SKYMONKEY PUBLISHING

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:)
GPS units are very complex & sensitive, to take the data they provide as 100% accurate is foolish. Especially for the units which are currently available on the general market. Many times I have obtained data from them which I knew immediately was completely incorrect. GPS data is best used as an indicator and only by looking at data from several flights together can you draw any conclusions.

All this discussion on this subject has become very entertaining. Fighting about how far or fast we all go. You or me or...
Why?! I understand the drive of some people who are trying to convince them self that they fly 3:1 GR or so. However that is just a dream right now. To get that glide ratio for several seconds - yes but to keep it for an entire skydive – no chance!!!

From my experience about the GR and speed I may say following:

There are a few well known rocks in Europe for which we know exactly how good you need to fly to get down safely.

A few require 2.1:1 and some even harder at 2.3:1. The funny thing is that only a handful of people so far have jumped them successfully.

Second important factor is endurance!!! I am first to admit that I can hold near perfect position (or what I think is perfect ) for about 40-50 sec.
So, does this factor also affect others?! Of course - YES!

GPS measurement of the speed of a WS flyer from 3000 or 4000m is more or less useless as the wind has a VERY significant effect on the flight. But I guess jumpers enjoy to read high numbers but maybe they also forget that the wind was there too.

speed:
My speed ( total ) is about 145-160 km/h for GR. Vertical ( in the BASE jumps where i go for GR) about 55kmh average.

Believe me , I would be the first who would be super happy to say that I had 3:1 GR average, but we are not there yet, regardless of what kind alchemy or formula we use.

Last year Loic in Russia had 1.9 GR.
This year Valery got 2.9 GR.
Well, was there more wind this year?! Yes!

Going back to rocks, Can I remember some jumps with such a drastic performance increase?! Yes, a few, but the weather conditions were near perfect! Lots of thermal wind etc...

In overall; writing that glide is 3:1 or that Speed on Phantom is 160 for GR jump is not correct – flying Wingsuit is not this straight forward!
Robert Pecnik
robert@phoenix-fly.com
www.phoenix-fly.com

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From my experience about the GR and speed I may say following:

There are a few well known rocks in Europe for which we know exactly how good you need to fly to get down safely.

A few require 2.1:1 and some even harder at 2.3:1. The funny thing is that only a handful of people so far have jumped them successfully.



Why only few people are doing it is an interesting question. My answer is that it is Robi and VKB's fault ;).
Most people these days want to do one jump flying away from the wall and start swooping it on the second jump.

Seriously...

This year several jumpers in tracking gear were flying back high over the landing area from #6. High enough to pull over the lighthouse if they kept going. The Flying Finn as everyone called him was easily pulling over the lighthouse.

Pete the Aussie with less than 10 big wall BASE jumps was pulling pretty high over the landing area using tracking gear. None of these guys are thin and tall, neither are they using special thin rigs for tracking. They are average height and solidly built.

2.3 or 2.4 is not hard to fly just because only a few people have done it so far. Afterall, It has been done in a medium sized suit(Phantom) and with a big fat rig as well. For 50 second flights, endurance is not an issue for the phantom.

My view is that anyone that is of reasonable build can do it in the correct sized suit if they really want to in one season of jumping. The reason why only a few people are flying 2.3+ must be something else.

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In overall; writing that glide is 3:1 or that Speed on Phantom is 160 for GR jump is not correct – flying Wingsuit is not this straight forward!



Considering the source of the 2100m flight from Smellveggan in no wind, you are responsible for the 3:1 :P. A 2100m flight from Smellveggan in no wind is over 3:1 L/D whichever way you cut it. Are you saying that it never happened?

No one said 160km/h is the speed of Phantom for best glide. 108-116 mph(total speed along the vector) was the range of speeds observed by me on my normal Phantom jumps. That information was provided because Boris asked for it multiple times, it has no other relevance to this conversation. Simple. :)
What is your typical L/D in a Phantom? Because it is a reasonable assumption to make that Boris was flying better than you on that jump or atleast as good as you for you not to have caught up with him assuming it was a fair race to begin with.

Kris.

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I feel I must commend you Robert on your patience and perseverance with correcting discussions here. As usual in this forum, people get all worked up and wrapped around the axle over trivial oversimplifications of WS (such as number chasing), and as usual you sweep in and settle all drama with one simple fact-filled post. I was wondering how much longer that was going to continue, so thanks again for the patience to spend your time on something like this.
:)
"The evil of the world is made possible by nothing but the sanction you give it. " -John Galt from Atlas Shrugged, 1957

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:)Second important factor is endurance!!! I am first to admit that I can hold near perfect position (or what I think is perfect ) for about 40-50 sec.



Got any really good pics of what this position looks like in a Phantom??:ph34r:
- - -
I am not afraid of tomorrow, for I have seen yesterday and I love today.

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