WS today!
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Flying Lobster
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Re: WS today!
Some people aren't--right up to the point that they crash.RedBaron wrote:Gary, Bacil and I are going to give WS a shot today. Come on out if you're not scared by 20 mph south cross gusts LOL
marc
Great Googly-moo!
Timing is everything
Woodstock was sweet today - from 10A to 10:45A. After that, it died to nil. Most pilots arrived after 10:45A. Too bad. Left at 1P after Dave and Carlos showed up to keep Janni company.
Bacil
Bacil
But did you Fly?
Bacil,
Your condition report, with timing factor, is good, but...
Did anyone launch?
Your condition report, with timing factor, is good, but...
Did anyone launch?
Cragin
Douglas.Cragin(AT)iCloud(DOT)com
Weather - https://sites.google.com/site/hgweather/
Flying - http://craginsflightblog.blogspot.com/
Kay's Stuff- http://kayshappenings.blogspot.com/
GO to 50 https://sites.google.com/site/hgmemories/Home/50th
Douglas.Cragin(AT)iCloud(DOT)com
Weather - https://sites.google.com/site/hgweather/
Flying - http://craginsflightblog.blogspot.com/
Kay's Stuff- http://kayshappenings.blogspot.com/
GO to 50 https://sites.google.com/site/hgmemories/Home/50th
Did anybody launch?
Don't know. Janni didn't. Don't know about Dave or Carlos. Should have been at the Pulpit where it was blowing 30 (NOT!) 
Bacil
BacilUnusual day
Well it was a very unusual day. At around 1PM it was very light Gary had left and Bacil decided to leave as well. But then at around 2PM the wind started coming in straight and consistent. Janni was already set-up, Dave was setting up, and I quickly brought the glider. Conditions were so consistent we decided to let Dave give them a try. Perfect launch an off he went, he gained altitude very quickly. Janni went next, another textbook perfect launch. I launched last, once in the air there was a noticeable cross from the SW. At this point Dave was 2 grand over and Janni was even higher. We drifted North at very good clip, we were flying over Signal Knob. Janni decided to play around and go back to launch and come back later.
OK, it didn’t happen and no one flew. Typical forecasts are stronger than actual conditions but this was ridiculous. 2:00 PM Forecast: 25knots at 2K; actual: dead calm at launch. After the light short cycles when I arrived, it was very calm you could almost hear conversations in the houses below. But no it was Joe and Zelda who stop by on their way across the ridge.
It was good get some fresh air anyway
Carlos
OK, it didn’t happen and no one flew. Typical forecasts are stronger than actual conditions but this was ridiculous. 2:00 PM Forecast: 25knots at 2K; actual: dead calm at launch. After the light short cycles when I arrived, it was very calm you could almost hear conversations in the houses below. But no it was Joe and Zelda who stop by on their way across the ridge.
It was good get some fresh air anyway
Carlos
On a previous day where we had very light conditions at WS launch when there were strong winds at Winchester and Staunton, people speculated that mountain wave can actually block the wind at launch... If anyone has a mental picture of how this would work, please post so that the rest of us can be enlightened. The words "mountain wave blocking the winds at launch" sound good, but I can't visualize what is happening. This is important because you might actually get off and up in light conditions at launch and then be surprised by much stronger winds at altitude or a sudden change in wind velocity after you launched (as happened to Matthew and me in our paragliders). - Hugh
mountain wave, a speculative explanation
Hugh and gang, I'll take a crack at an explanation for the Wave/Woodstock effect. Please permit me first to admit that it is speculative and intended to seed some thought on the subject and not to presume it to be the "truth."
For this explanation I'd like to start with a molecular fluid model of the air, with individual little ping pong balls (molecules) jostling each other about generally flowing from locations where there are generally more of them to to locations where there are less, i.e. high to low pressure. From that premise I'll define a wave as a widespread area of periodic lift and sink that results from surface wind flow being interfered with at regular intervals. These regular intervals enable the rising and sinking air to lock into phase with each other thus sustaining and perhaps amplifying the lift along the leading portion of each wave. It is common to see lines of lenticular clouds set up over the mountains of west virginia while flying west out of Dulles Airport.
Now for the conjecture. In order for the ping pong balls to create lift they must have translated a portion of the horizontal surface winds to the vertical component creating the lift. If the lift is created by interference with more densely packed molecules ahead rather than surface heating as suggested by this conjecture, then the kinetic and potential energy gained by the rising air is proportional to the loss in kinetic energy along the horizontal axis which in turn translates to a loss in horizontal velocity.
Note that while any west to east flowing air must be rising along the surface of the west facing ridges, the wavelengths do not have to be equal to the distances between ridges, the can be integer fractions of those distances. Therefore it should not be a surprise to find a wave peak in the center of the valley.
Conclusion: We are seeing the Woodstock effect because the uniformly spaced ridges to the west create standing waves that act as barriers to the flow of the prevailing westerly winds and translate some of their energy to lift just as the mountains do. Since this lift occurs over a wide area along all axes the effect is small when measured across a small area such as the footprint of our launch slot. This is why we don't notice the lift while standing on launch.
What this means to the pilots: I contend that wave is common around Woodstock. I believe that if we were to carefully measure the average wind velocities, both speed and direction, we would find a high correlation between observed wave and those velocities. Different velocities would set up different wavelengths most of which would self cancel rather than organize.
I've only been in wave at Woodstock once and that one time I stumbled into it well out in the valley. I have a hunch that if we spent more time trying to fly to I 81 or further and back we'd hit it often. Perhaps some of the wave catching experts like Nelson Lewis can shed some light on the subject.
Rebuttal to the conclusion: If I were trying to rebut my own argument I'd argue that the collisions between the air molecules are elastic and don't contribute to a net change in direction from horizontal to vertical. I'll leave that argument to one of you.
Dan T
For this explanation I'd like to start with a molecular fluid model of the air, with individual little ping pong balls (molecules) jostling each other about generally flowing from locations where there are generally more of them to to locations where there are less, i.e. high to low pressure. From that premise I'll define a wave as a widespread area of periodic lift and sink that results from surface wind flow being interfered with at regular intervals. These regular intervals enable the rising and sinking air to lock into phase with each other thus sustaining and perhaps amplifying the lift along the leading portion of each wave. It is common to see lines of lenticular clouds set up over the mountains of west virginia while flying west out of Dulles Airport.
Now for the conjecture. In order for the ping pong balls to create lift they must have translated a portion of the horizontal surface winds to the vertical component creating the lift. If the lift is created by interference with more densely packed molecules ahead rather than surface heating as suggested by this conjecture, then the kinetic and potential energy gained by the rising air is proportional to the loss in kinetic energy along the horizontal axis which in turn translates to a loss in horizontal velocity.
Note that while any west to east flowing air must be rising along the surface of the west facing ridges, the wavelengths do not have to be equal to the distances between ridges, the can be integer fractions of those distances. Therefore it should not be a surprise to find a wave peak in the center of the valley.
Conclusion: We are seeing the Woodstock effect because the uniformly spaced ridges to the west create standing waves that act as barriers to the flow of the prevailing westerly winds and translate some of their energy to lift just as the mountains do. Since this lift occurs over a wide area along all axes the effect is small when measured across a small area such as the footprint of our launch slot. This is why we don't notice the lift while standing on launch.
What this means to the pilots: I contend that wave is common around Woodstock. I believe that if we were to carefully measure the average wind velocities, both speed and direction, we would find a high correlation between observed wave and those velocities. Different velocities would set up different wavelengths most of which would self cancel rather than organize.
I've only been in wave at Woodstock once and that one time I stumbled into it well out in the valley. I have a hunch that if we spent more time trying to fly to I 81 or further and back we'd hit it often. Perhaps some of the wave catching experts like Nelson Lewis can shed some light on the subject.
Rebuttal to the conclusion: If I were trying to rebut my own argument I'd argue that the collisions between the air molecules are elastic and don't contribute to a net change in direction from horizontal to vertical. I'll leave that argument to one of you.
Dan T
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bustedwing2
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duh2cents
Aerodynamics and hydrodynamics are quite similar if not near identical,primary difference being the density of the medium,perhaps a 2 by 4 foot sheet of plywood with 'to scale' plaster ridges submerged in a shallow fast moving stream would make it possible to visualize what is happening with wave.Stand on an ocean beach and watch the waves roll across the sandbars,break on the beach,and the 'reflection' of returning flow.Harmonics also should enter into the picture,whats water without a little mud?Brian you got a formula for this? RichB
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Danny Brotto
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Hey Hughmcelrah wrote:If anyone has a mental picture of how this would work, please post so that the rest of us can be enlightened. - Hugh
Why not attempt a practical picture? Take your trike out on one of these "conundrum" days and experiment for yourself. I think you could get a decent mental wind map by flying up and down the ridge and into the valley to gain that wind-profile picture.
When ridge flying, sailplane pilots are always alert to wave-induced ridge lift cancellation. The issue is bombing down a perfectly good ridge in perfectly good conditions only to have the bottom fall out necessitating a quick landing. Kollie and some of the Front Royal regulars might help illuminate what happens at WS especially in the vicinity of the HG launch during strong conditions.
Based on conversations with glider pilots out of Front Royal, the Massanutten wave is known to set up and to be stronger and more consistent towards the north of the HG launch; closer to Strausburg.
Danny Brotto
Ya, this could also explain what happened this summer when Gary Smith and I went up to the reservoir and got high, hoping to jump over the back and land at Front Royal airport. I had done this a couple of years before in my Eagle, so figured it should be easily doable again with a U2, but as soon as I turned downwind with 3k over the ridge, I got hammered and ended up stuck on the back ridge south of Buzzard Rocks, had to go land in the Fort Valley, getting rotored all the way. (This is the day Joe Gregor got injured, so people can remember the conditions.)
Not interested in trying strong conditions in the trike - much more comfortable on strong days in the hang-glider. There's something about the pendulum effect of 700 pounds of trike (865 max with two up) under the same number of squares...
- Hugh
Not interested in trying strong conditions in the trike - much more comfortable on strong days in the hang-glider. There's something about the pendulum effect of 700 pounds of trike (865 max with two up) under the same number of squares...
- Hugh
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Danny Brotto
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Flying Lobster
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I used to do my own Skew T's with RAOB (http://www.raob.com/) and also used the mountain wave module. Of all the areas I used the mountain wave predictor module, the Woodstock area more consistently came up with positive "likely" results for predictions of wave occurrence than any other HG site I flew in the region.
The primary conditions for the theoretical propagation of wave had more to do with upwind topography "trigger" mountains, specifically height and slope shape, and the occurrence of lower surface to boundary layer of instability which is topped by a thick layer of stability. The upwind trigger--probably the mountains to the west of Woodstock, serve as the trigger of the initial wave, while the presence of the right layers of surface instability to upper stable layer provide the medium for the continued propagation of the wave downwind. Where the waves actually position themselves relative to up and down sides of the "amplitude" is also affected by wind velocity and the relative thickness of the air masses. Interestingly, wind velocity alone is apparently not the primary factor in whether or not wave occurs--in other words wave can happen on days that are not necessarily "honkin" days.
Nelson is definitely the best expert I know of in using wave for HG flight--he's gone over 70 miles using 7 or eight wave "amplitudes." I've done 20 or so miles in a few amplitudes.
My experience with wave is that you are tangling with potentially powerful forces that can easily overwhelm a hang glider even if conditions seem reasonable when launching. I've gone up through clouds in the rising side of wave with VG full on on a topless with bar full stuffed and was still going backwards and up at around 50 miles an hour AS--climbing well above the cloud layers and the glider getting entirely covered with a thin coating of rime-ice.
Getting in the "backside" or downward portion of the wave amplitude can be a violently turbulent place which can easily overwhelm a hang glider.
I was watching a PBS program last night about the US government's 13,000 square mile "quiet zone" which is immediately west and south of the Woodstock area. All emitters of wireless interference are prohibited so that deep-space antenna arrays can listen for weak radio waves from outer reaches of the galaxy. Not surprisingly, the military and AT&T has positioned their own dish arrays to "listen" for transcontinental and intercontinental communications in the quiet zone.
Perhaps this all has something to do with the "Woodstock" effect?
marc
The primary conditions for the theoretical propagation of wave had more to do with upwind topography "trigger" mountains, specifically height and slope shape, and the occurrence of lower surface to boundary layer of instability which is topped by a thick layer of stability. The upwind trigger--probably the mountains to the west of Woodstock, serve as the trigger of the initial wave, while the presence of the right layers of surface instability to upper stable layer provide the medium for the continued propagation of the wave downwind. Where the waves actually position themselves relative to up and down sides of the "amplitude" is also affected by wind velocity and the relative thickness of the air masses. Interestingly, wind velocity alone is apparently not the primary factor in whether or not wave occurs--in other words wave can happen on days that are not necessarily "honkin" days.
Nelson is definitely the best expert I know of in using wave for HG flight--he's gone over 70 miles using 7 or eight wave "amplitudes." I've done 20 or so miles in a few amplitudes.
My experience with wave is that you are tangling with potentially powerful forces that can easily overwhelm a hang glider even if conditions seem reasonable when launching. I've gone up through clouds in the rising side of wave with VG full on on a topless with bar full stuffed and was still going backwards and up at around 50 miles an hour AS--climbing well above the cloud layers and the glider getting entirely covered with a thin coating of rime-ice.
Getting in the "backside" or downward portion of the wave amplitude can be a violently turbulent place which can easily overwhelm a hang glider.
I was watching a PBS program last night about the US government's 13,000 square mile "quiet zone" which is immediately west and south of the Woodstock area. All emitters of wireless interference are prohibited so that deep-space antenna arrays can listen for weak radio waves from outer reaches of the galaxy. Not surprisingly, the military and AT&T has positioned their own dish arrays to "listen" for transcontinental and intercontinental communications in the quiet zone.
Perhaps this all has something to do with the "Woodstock" effect?
marc
Great Googly-moo!
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theflyingdude
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That's the reason there is no cellphone service in the New Germany Valley of WV (the Spruce Knob and North Mtn flying sites are located there). They can't hear ET if there are a bunch of hillbillies yakking up the airwaves.Flying Lobster wrote:I was watching a PBS program last night about the US government's 13,000 square mile "quiet zone" which is immediately west and south of the Woodstock area. All emitters of wireless interference are prohibited so that deep-space antenna arrays can listen for weak radio waves from outer reaches of the galaxy. Not surprisingly, the military and AT&T has positioned their own dish arrays to "listen" for transcontinental and intercontinental communications in the quiet zone.
Perhaps this all has something to do with the "Woodstock" effect?
marc
JR
waves and boundary layers
Good explanation Marc. The models that predict the waves must incorporate an understanding of the physics. it would be interesting to see what they say about explaining why the winds are often so light at Wooodstock.
I've visited that radio telescope site, it's pretty interesting. One think I learned is that all the motor vehicles associated with working around the site are diesel engines. No spark plugs means no radio interference at those wavelengths and their harmonics.
Dan T
I've visited that radio telescope site, it's pretty interesting. One think I learned is that all the motor vehicles associated with working around the site are diesel engines. No spark plugs means no radio interference at those wavelengths and their harmonics.
Dan T
Ya, Naval Security Group Activity, Sugar Grove was sited there in the National Radio Quiet Zone along with the Green Bank radio astronomy facility. Interesting to have a bunch of guys in Navy uniforms hundreds of miles from blue water. When I was a Lieutenant, I went with a buddy - who actually knew what he was doing - to run an experiment using one of NSGA's 60-foot dishes. Boys and their toys. Not sure the Navy site is still open...
I like the idea of exploring the airflow around Woodstock in a Diamond DA-20 (Katana - they have another model name, too) - basically a motorglider design with shortened wings. I have rented them from the FBO at Leesburg airport. How do unpowered sailplanes handle wave? Fun vs. scary/dangerous? How do you make a go/no-go decision for flying in wave in sailplanes and hang-gliders? I suppose it's a matter of testing the air and retreating if it's more than you want to deal with...
- Hugh
I like the idea of exploring the airflow around Woodstock in a Diamond DA-20 (Katana - they have another model name, too) - basically a motorglider design with shortened wings. I have rented them from the FBO at Leesburg airport. How do unpowered sailplanes handle wave? Fun vs. scary/dangerous? How do you make a go/no-go decision for flying in wave in sailplanes and hang-gliders? I suppose it's a matter of testing the air and retreating if it's more than you want to deal with...
- Hugh
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Danny Brotto
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Local unpowered glider pilots can climb into wave using thermals that punch right up into the stable wave layer. Sometimes thermals will boost you to the rotor below the wave in which case you need to climb using the rotor to access the wave. Alternately you can pay for the iron thermal (tug) to take you directly to the wave; 3500 to 5000 usually does it. That’s a high tow but if the thermals are not happening or just ripped apart by the wind, it may be the only play. The latest gig at our filed is to take an early tow (8:00 am) into the wave and fly upwind (yes, that’s upwind) to the ridges (Tusk or even up to the Bald Eagle) to gain XC distance running the ridges well before thermals start. At Fairfield we have wave entry points that are pretty reliable given various wind strength and direction. I suspect the same is true with the Massanutten ridge.mcelrah wrote: I like the idea of exploring the airflow around Woodstock in a Diamond DA-20 (Katana - they have another model name, too) - basically a motorglider design with shortened wings. I have rented them from the FBO at Leesburg airport. How do unpowered sailplanes handle wave? Fun vs. scary/dangerous? How do you make a go/no-go decision for flying in wave in sailplanes and hang-gliders? I suppose it's a matter of testing the air and retreating if it's more than you want to deal with...
- Hugh
In this area, wave flying is a hoot and generally reliable. We fly with O2 and regularly get to over 10K MSL. 13K+ is not unusual. You do need to keep an eye out for getting caught over the top (of the clouds.) But I can turn downwind and travel at 100 MPH+ groundspeed to escape if needed. If you are using the wave to get to the ridges, then you need only climb high enough to get to the next wave bar. The rotor can be testy but not dangerous; it’s just bumpy/rumbly. (I’m more uncomfortable in the HG on a bumpy thermal day than in the sailplane on a wave induced rotor day.) Out west where the mountains are tall, violent rotor can be generated so it’s a different story there. Also there’s a big wave site in Petersburg WV which has been known to produce tall wave and equally big rotor.
From my experience, HG’s encounter wave more than is realized it’s just not recognized. Often the HG pilot will sense the lift as if it were thermal lift, circle in the wave, and get blown downwind out of the lift. I’ve encountered generous wave on various occasions at High Rock and the Pulpit and once at the Sac.
Tomorrow looks to be a very nice wave day. There’s some talk of the possibility of 16K+ over Waynesboro!
Danny Brotto
Where are those antenna located? It's not the place beside I-81, is it?Flying Lobster wrote:
I was watching a PBS program last night about the US government's 13,000 square mile "quiet zone" which is immediately west and south of the Woodstock area. All emitters of wireless interference are prohibited so that deep-space antenna arrays can listen for weak radio waves from outer reaches of the galaxy. Not surprisingly, the military and AT&T has positioned their own dish arrays to "listen" for transcontinental and intercontinental communications in the quiet zone.
Perhaps this all has something to do with the "Woodstock" effect? Laughing
marc
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Flying Lobster
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I think I know the ones you're talking about--south of Woodstock but before the end of the ridge run? I think the deep space listener is somewhere near Reddish Knob--a place I used to go camping at when I was a kid--and I think Bill Bennett and maybe some other west-by-gods actually once flew many years ago--eh JR?bigkreek wrote:Where are those antenna located? It's not the place beside I-81, is it?Flying Lobster wrote:
I was watching a PBS program last night about the US government's 13,000 square mile "quiet zone" which is immediately west and south of the Woodstock area. All emitters of wireless interference are prohibited so that deep-space antenna arrays can listen for weak radio waves from outer reaches of the galaxy. Not surprisingly, the military and AT&T has positioned their own dish arrays to "listen" for transcontinental and intercontinental communications in the quiet zone.
Perhaps this all has something to do with the "Woodstock" effect? Laughing
marc
marc
Great Googly-moo!
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theflyingdude
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The radio telescope is located at Green Bank, WV and that's south of Spruce Knob, but I've not heard about any flying from Reddish Knob (which is actually in VA). Bill Bennett may have flown from there at some point in time, but I don't remember him telling me about it. Perhaps he and Bobbie Killingsworth flew from there in the old, old days or maybe it was a bandito-operation that he didn't want to advertise.Flying Lobster wrote:I think I know the ones you're talking about--south of Woodstock but before the end of the ridge run? I think the deep space listener is somewhere near Reddish Knob--a place I used to go camping at when I was a kid--and I think Bill Bennett and maybe some other west-by-gods actually once flew many years ago--eh JR?bigkreek wrote:Where are those antenna located? It's not the place beside I-81, is it?Flying Lobster wrote:
I was watching a PBS program last night about the US government's 13,000 square mile "quiet zone" which is immediately west and south of the Woodstock area. All emitters of wireless interference are prohibited so that deep-space antenna arrays can listen for weak radio waves from outer reaches of the galaxy. Not surprisingly, the military and AT&T has positioned their own dish arrays to "listen" for transcontinental and intercontinental communications in the quiet zone.
Perhaps this all has something to do with the "Woodstock" effect? Laughing
marc
marc
JR
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Flying Lobster
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I'm pretty sure the program mentioned Reddish Knob--maybe some other kind of communications array is near there. I once had a conversation with Bill about developing some remote knobs in VA/ WVA area (GW forrest etc.) and I seem to recall Bill mentioning having flown Reddish (some time BC)--which I couldn't see as possible being so remote. One of those projects (or was it Logan's?)--Fetzer's Gap--was the pinnacle of infamy in my paragliding career.
marc
marc
Great Googly-moo!