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outrager
United States
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: 416
: 11 years
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Jul 22, 2009, 12:42 PM
Post #1 of 39
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Registered: Mar 13, 2002
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Real life L/D challenge at Eiger
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Can't Post
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Yo !
All this talk about downwind 3.5 glide flights reminded me about a very nice real-life L/D challenge that's still to be conquered:
Try flying from the Mushroom (Eiger) all the way down to Grindenwald. It's a scenic and intense flight over the rolling hills. You will need to cover about 5000m distance to use all 2200m of available altitude, requiring a measly 2.6-2.7 L/D average depending on how much altitude you allow for a start and deployment. Exit altitude is 3200m, which puts it rather close to a skydive. Wind will not be a significant factor: you have to pick a quiet day to survive. Access is easy, start is safe, and LZs are bigger than most DZs 
Plenty of attempts have been done from this exit over the years, and AFAIK the challenge remains. It should be so easy now with the new suits, eh? C'mon, do it, even at 2.9 you'll be a rock star! 
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mccordia
Netherlands
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: 1800
: D 94775
: 7 years
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Jul 22, 2009, 1:02 PM
Post #2 of 39
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Registered: Feb 28, 2001
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Re: [outrager] Real life L/D challenge at Eiger
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Sounds like a great challenge..
Whats the furthest distance flown so far on this jump?
And are there any videos online on previous attempts?
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mccordia
Netherlands
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: 1800
: D 94775
: 7 years
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Jul 22, 2009, 1:33 PM
Post #4 of 39
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Re: [outrager] Real life L/D challenge at Eiger
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Are you flying a V3 already? Any attempts planned in the (your) near or far future?
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yuri_base
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Jul 22, 2009, 1:42 PM
Post #5 of 39
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Re: [outrager] Real life L/D challenge at Eiger
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At 3.52 actual and a mere 2.62 required, this must be piece of cake for Tony.
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Eiger.png
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Zeemax
United Kingdom
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: 103535
: 6 years
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Jul 22, 2009, 2:30 PM
Post #7 of 39
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Registered: Jan 27, 2003
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Re: [outrager] Real life L/D challenge at Eiger
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Depending on where in Scotland, you're only 3 1/2 hours on a train up down the country.
We should have a beer 
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outrager
United States
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: 416
: 11 years
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Jul 22, 2009, 3:47 PM
Post #13 of 39
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Re: [mccordia] Real life L/D challenge at Eiger
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Is that video still online somewhere....I recall seeing that one a long time ago. I think thats still the longest/furthest B flight in a wingsuit up to this date if Im not wrong?? Ostankino '04: http://base416.com/...no04/Pond_Flight.mov This year's Burj Dubai WS flight is roughly twice as high, though.
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Tony-tonysuits
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: 8000
: D 1460
: 35 years
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Jul 22, 2009, 4:40 PM
Post #16 of 39
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Re: [outrager] Real life L/D challenge at Eiger
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ok, I'll do it, ive never done a wingsuit base and I dont like pulling low but....hmmm maybe we can get Toby to do it, you reading this Toby, he doesnt like to pull low either, 300 m.
Heres a question, does the G/R improve with lower thicker air? it sure feels like it.
I know in a plane you gotta go higher to go faster, so, is that the same with a wingsuit?
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mfnren
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: 900
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: 7 years
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Jul 22, 2009, 4:49 PM
Post #17 of 39
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Re: [Tony-tonysuits] Real life L/D challenge at Eiger
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you won't be going any lower than 3,300 msl, hopefully...
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outrager
United States
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: 416
: 11 years
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Jul 22, 2009, 5:06 PM
Post #18 of 39
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Re: [Tony-tonysuits] Real life L/D challenge at Eiger
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Can't Post
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ok, I'll do it, ive never done a wingsuit base and I dont like pulling low but....hmmm maybe we can get Toby to do it, you reading this Toby, he doesnt like to pull low either, 300 m.
Somebody has to!
You should be able to pull at 300m over the village at L/D of 2.9.
If you do fly at 3.5 you will be pulling at 600m. These numbers assume 200m of altitude wasted for a lazy start, obviously that can be done better.
Heres a question, does the G/R improve with lower thicker air? it sure feels like it.
It does not. True airspeed (i.e. both vertical and horizontal, proportionally) does increase with altitude, so starting a suit higher up will take slightly longer. Sustained L/D will be the same at any altitude, assuming that you are indeed flying.
Google, like http://www.stolaf.edu/.../spd2fly/densalt.htm if you want to know why in detail.
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yuri_base
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Jul 22, 2009, 7:26 PM
Post #20 of 39
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Registered: Oct 21, 2005
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Re: [mccordia] Real life L/D challenge at Eiger
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Actually, sustained glide ratio is slightly higher than L/D, because as you're flying into continuously denser air, you're constantly moving at slightly higher speed than true sustained speed for current layer, so effectively, you're constantly plane out.
The effect is tiny, about 1%: if you enter, for example, Vxs=100mph, Vys=40mph (L/D=2.5) in Wingsuit Equations module in Wingsuit Studio, you will see that sustained glide ratio is about 2.53.
That's nothing compared to secret method of bumping G.R. by 40% discovered by Tony in Marl.
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michalm21
United States
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: 600
: C 36728
: 3 years
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Jul 22, 2009, 7:34 PM
Post #21 of 39
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Re: [yuri_base] Real life L/D challenge at Eiger
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do you even skydive?
edit: no pun, honest question.
(This post was edited by michalm21 on Jul 22, 2009, 7:35 PM)
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Deniq
Germany
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: 4 years
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Jul 23, 2009, 1:16 AM
Post #22 of 39
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Registered: Jul 14, 2008
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Re: [yuri_base] Real life L/D challenge at Eiger
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The influence of altitude wind on the glide ratio is huge! The second point is the exit and main deployment procedure...
Look on one my GPS-track.
Glide Ratio is:
In Race Zone 5285/2071=2,55.
For whole track: (619+5285+864)/(551+2071+1397)=1,68
If you see "Ground Speed Graph", you can see decreasing of my ground speed from 250+ to 150 kmh.
The "Vertical Speed" is here all time more or less constant.
If I understood "outrager", for the Eiger challenge you need glide ratio of 2,6 for whole track 
(This post was edited by Deniq on Jul 23, 2009, 1:18 AM)
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td_plot5435.pdf
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grayhghost
Jumps
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: 270
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: 1 years
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Oct 9, 2009, 10:39 AM
Post #23 of 39
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Registered: Jul 27, 2006
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Re: [michalm21] Real life L/D challenge at Eiger
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looks like it got done:
http://www.matttg.com/eiger.htm
nice work Mattt!
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yuri_base
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Oct 10, 2009, 11:25 AM
Post #24 of 39
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Re: [grayhghost] Real life L/D challenge at Eiger
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Awesome stuff!
Dean Potter is most likely the 1st in the world who flew from Mushroom to Grindelwald [several times in his Xcess]. From jumping with him and watching his flights, he has a very good glide at quite slow sustained speeds, both vertical and horizontal. Low wingloading allows for quick start (which doesn't require high L/D per se; max lift mode with about 45 degree angle of attack, despite having L/D of about 1.0, pulls you from the wall the fastest; then switch to higher L/D "gear" by controlling your pitch and ensuring lower AoA).
Sometimes he wouldn't be able to repeat it and I mentioned to him that it might be the headwind affecting his glide. With 2m 50s flights from the higher exit, a 20mph tailwind gives a free mile of distance, while the same headwind takes it from you. For such long flights, wind can be used creatively to do flights that would otherwise be impossible to do.
As can be seen from Wingsuit Studio simulations, longer (slower) flights allow lower L/D threshold to achieve the same goal compared to faster flights. In this example, compare two flights from the Mushroom, one is 120s long and the other 150s long. And that's without the tailwind - with tailwind the effect is even more drastic!
I'm sure we'll see lots of other amazing things done by Dean in the near future!
Yuri
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120s.png
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150s.png
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mariavon
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: 3 years
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Oct 15, 2009, 6:28 AM
Post #25 of 39
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Registered: Jun 30, 2004
Posts: 43
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Re: [yuri_base] Real life L/D challenge at Eiger
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Yuri, if one flew at a glide ratio of 4.5:1 , what more or less would you guess the vertical speed to be, and what would the ground speed be, and distance covered ? i guess there are variables but in very average conditions?
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