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#11
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One important point, learned the hard way. You don't want to push over to 110 knots, still climbing like crazy, push to VNE, still climbing and clouds approaching, and THEN want to open the spoilers. Obviously you don't want to jam open the spoilers at VNE, too many wings have fallen off that way. And if you pull back to a sensible speed, you gain 2000' in the zoom. Pull the spoilers while still sensibly away from the cloud! In my case, I was lucky enough to not go in to the cloud, but others have not been so lucky.
John Cochrane BB |
#12
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John Cochrane wrote on 9/2/2020 12:19 PM:
One important point, learned the hard way. You don't want to push over to 110 knots, still climbing like crazy, push to VNE, still climbing and clouds approaching, and THEN want to open the spoilers. Obviously you don't want to jam open the spoilers at VNE, too many wings have fallen off that way. And if you pull back to a sensible speed, you gain 2000' in the zoom. Pull the spoilers while still sensibly away from the cloud! In my case, I was lucky enough to not go in to the cloud, but others have not been so lucky. John Cochrane BB Your recommendation is a very good one, but it's my understanding our gliders are designed and tested to withstand opening the spoilers at Vne. You should avoid abrupt opening above maneuvering speed (perhaps that is what you meant), and the G load before opening should be lower than the maximum allowed at Vne - check the handbook. -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me) - "A Guide to Self-Launching Sailplane Operation" https://sites.google.com/site/motorg...ad-the-guide-1 |
#13
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Designed and tested, well maybe, but I got some nice bruises from my straps across my chest in the process of making the same mistake as John. https://www.youtube.com/watch?v=hRH5tf4iuKk
The IGC log showed the lift peaked at 45kts. Airbrakes still didn't induce a descent, the only escape was out the side. If you're still climbing at +5kts while cruising 100kts, it's time to make an exit plan because the 'corner' comes quicker than you expect. I'd done it loads of times before and the lift had never been strong enough that it 'overpowered' VNE... until that time... On Wednesday, September 2, 2020 at 10:51:36 PM UTC+2, Eric Greenwell wrote: John Cochrane wrote on 9/2/2020 12:19 PM: One important point, learned the hard way. You don't want to push over to 110 knots, still climbing like crazy, push to VNE, still climbing and clouds approaching, and THEN want to open the spoilers. Obviously you don't want to jam open the spoilers at VNE, too many wings have fallen off that way. And if you pull back to a sensible speed, you gain 2000' in the zoom. Pull the spoilers while still sensibly away from the cloud! In my case, I was lucky enough to not go in to the cloud, but others have not been so lucky. John Cochrane BB Your recommendation is a very good one, but it's my understanding our gliders are designed and tested to withstand opening the spoilers at Vne. You should avoid abrupt opening above maneuvering speed (perhaps that is what you meant), and the G load before opening should be lower than the maximum allowed at Vne - check the handbook. -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me) - "A Guide to Self-Launching Sailplane Operation" https://sites.google.com/site/motorg...ad-the-guide-1 |
#14
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I find lift in rain or virga about 50% of the time. Lift is nearby if it is not in the rain. Climbing is usually slower in wet lift because the rain does drag air downward with it, it cools the air, and the glider's performance is degraded. One should have a plan on escaping out of a microburst. I am convinced that microbursts exist in clear air, away from clouds, in which case it is difficult to determine which way to run because the downdraft is invisible, making them scarier than the mature Cumulus kind.
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#15
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On Tuesday, September 1, 2020 at 11:19:22 AM UTC-7, ProfJ wrote:
Typing this with my fireproof suit on...last weekend I tried to duck between two rainy cumulus clouds on my glide back to home base. As I went through the gap it became filled with virga and I was sucked rapidly upwards, probably would have been about 10m/s if I had not had the nose well down. This was not tranquil, but not terrifying either (I was about 3000 ft below cloudbase) and added some useful height and speed. So here's the question: would you (do you?) deliberately head into virga if you needed the boost, or is this a truly dumb thing to do? Same for rain clouds (assuming you are in updraft not downdraft zone), how close would you get? Not looking for legal technicalities here, this was good VFR at all times - just trying to calibrate risk. I've flown a LOT in the Great Basin (Ely, Parowan) and the advice of one of my more successful soaring mentors,Carl Herold, has proven to me far more often true more than false. He advised to avoid Virga if the temperature at your current altitude is warmer than freezing and fly directly toward and through the snow virga where the temperatures at your altitude is colder than freezing. That air will be rising! I have no idea why this works, but it has proven to be a successful strategy far more often than not. |
#16
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On Saturday, September 5, 2020 at 10:49:25 PM UTC-6, wrote:
On Tuesday, September 1, 2020 at 11:19:22 AM UTC-7, ProfJ wrote: Typing this with my fireproof suit on...last weekend I tried to duck between two rainy cumulus clouds on my glide back to home base. As I went through the gap it became filled with virga and I was sucked rapidly upwards, probably would have been about 10m/s if I had not had the nose well down. This was not tranquil, but not terrifying either (I was about 3000 ft below cloudbase) and added some useful height and speed. So here's the question: would you (do you?) deliberately head into virga if you needed the boost, or is this a truly dumb thing to do? Same for rain clouds (assuming you are in updraft not downdraft zone), how close would you get? Not looking for legal technicalities here, this was good VFR at all times - just trying to calibrate risk. I've flown a LOT in the Great Basin (Ely, Parowan) and the advice of one of my more successful soaring mentors,Carl Herold, has proven to me far more often true more than false. He advised to avoid Virga if the temperature at your current altitude is warmer than freezing and fly directly toward and through the snow virga where the temperatures at your altitude is colder than freezing. That air will be rising! I have no idea why this works, but it has proven to be a successful strategy far more often than not. I've picked up 1.5" of virga snow on the leading edges in July at FL170 in Colorado. So flying across the band is a good idea to minimize accumulation. Lift was fine and didn't seem to affect the stability of the glider, LAK12, though I was concerned at the time. Sublimated after a few minutes back in clear air. Frank |
#17
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On 9/6/2020 7:39 AM, Frank Whiteley wrote:
On Saturday, September 5, 2020 at 10:49:25 PM UTC-6, wrote: On Tuesday, September 1, 2020 at 11:19:22 AM UTC-7, ProfJ wrote: Typing this with my fireproof suit on...last weekend I tried to duck between two rainy cumulus clouds on my glide back to home base. As I went through the gap it became filled with virga and I was sucked rapidly upwards, probably would have been about 10m/s if I had not had the nose well down. This was not tranquil, but not terrifying either (I was about 3000 ft below cloudbase) and added some useful height and speed. So here's the question: would you (do you?) deliberately head into virga if you needed the boost, or is this a truly dumb thing to do? Same for rain clouds (assuming you are in updraft not downdraft zone), how close would you get? Not looking for legal technicalities here, this was good VFR at all times - just trying to calibrate risk. I've flown a LOT in the Great Basin (Ely, Parowan) and the advice of one of my more successful soaring mentors,Carl Herold, has proven to me far more often true more than false. He advised to avoid Virga if the temperature at your current altitude is warmer than freezing and fly directly toward and through the snow virga where the temperatures at your altitude is colder than freezing. That air will be rising! I have no idea why this works, but it has proven to be a successful strategy far more often than not. I've picked up 1.5" of virga snow on the leading edges in July at FL170 in Colorado. So flying across the band is a good idea to minimize accumulation. Lift was fine and didn't seem to affect the stability of the glider, LAK12, though I was concerned at the time. Sublimated after a few minutes back in clear air. IMO this is the sort of fundamental question/scenario every thoughtful glider-guider should-oughta more-wisely ponder *before* encountering in the wild than after, and in that sense RAS - with all the faults and virtues found in humankind - can be a useful resource. As with all free inputs...chose wisely your sources of perceived wisdom. :-) For the record, 100% of my virga experience comes from above Colorado. Whether or not it's "a lot" I really can't judge...but almost all of it has been some combination of: fun, "fun", of considerable-knollich-gained content. While it's difficult to make defensible sweeping generalizations about my experiences, I distinctly remember a few instances. I remember the first time I gained altitude while flying through a band of it (of the fine mist sort, judging from the canopy) located between me and where I wanted/"needed" to go. One working conclusion - me being from the philosophical school of "If it happens it must be possible." - was along the lines of: evidently air can be rising faster than "water-based-'stuff' can be falling." (Duh!) The notion hadn't occurred to me, prior. I remember the first time I had a "Frank's experience" (see above). I picked up ~0.5" rime ice along both leading edges while descending through a rotor cloud over the foothills as part of executing my version of moving from a region of "reducing safety/WX margins" to one of "expanding safety/WX margins" west of Fort Collins. Happened amazingly rapidly...and wasn't a serious concern because I was in a landing-flapped-only ship (i.e. no concern about IMC spiral diving issues), and knew that there were thousands of feet of terrain clearance betwixt rotor and rocks. "For fun" and out of curiosity, once beneath the rotor, I "de-flapped" and performed some stalls just because I could...with no detectable effects upon nominal stall speeds/characteristics - from which I concluded "not a darned thing in general terms!" The rime sublimated within minutes of reaching clear air. Perhaps more to the point(s?) of the original post/questions, it may be of more enduring "takeaway interest" to ponder the "hows and wherefores" of actually reaching a situation where Joe Glider Pilot might choose to seriously consider an IMC descent as "desirable." CO's mountains between (say) Denver and Fort Collins, while rising abruptly from the Great Plains, don't do so in the manner of (say) the Sierras or those of Nevada's basin and range mountains. They instead are crumply little things for tens of miles extending westward in a disorganized, generally rising, mass to eventually become the continental divide (between Gulf of Mexico/Pacific drainages), which in that region is the primary wave generation source, generally some 25-40 miles west of the mountains/plains interface. On "non-hydraulic jump" days - by far more common than days of "single monster waves" - such as this one was, it's not uncommon for the tertiary rotor to still be located above the front range crumplies. I no longer remember if I was wave soaring above the secondary or the tertiary rotor band, but because the day was one of those CO days "of significant moisture" (not rare but not uncommon, either), I'd intentionally decided to run N/S (from Boulder) above the foothills rather than explore vertically - BTDT years before and got it out of my system - by way of a) learning more about those sort of wave systems, and b) cloud/terrain avoidance. In short, a nod toward WX/terrain conservatism. The farther north I got, the cloudier it became, until I reached my personal comfort/convenience limits, and my "what to do next?" choices seemed to be: 1) execute the time-tested 180-degree turn; 2) push my convenience limits by continuing north above the rotor (no pre-arranged retrieve crew); 3) retreat east (to clearer skies and almost guaranteed convective lift lower down). What I chose to do was a flavor of option 3) (multiple flavors existed), the one most interesting to me, then. Being off the descent routes into Denver'a A/P just there and the day not being one where "general aviation types" would've been out fun-flying (as opposed to IMC flight plan flying), I chose the direct vertical descent over that of doing so either upwind/downwind of the rotor band. (I hereby formally apologize to every gen-aviation pilot who was put at risk by my callous disregard for their IMC safety, and note that no evidence of my intentional FAR-busting exists in any of my logbooks. I think some statute of limitation likely applies, anyway!) In hindsight, I considered my choices Most Eminently Personally Satisfying and Suitably Educational. And, no, I would NOT have made the same choice had I not've been flying a landing-flap-only equipped sailplane. In "Kentucky windage" terms, I'd guess more than half my virga encounters have resulted in net altitude gains, with a few quite - QUITE! - the opposite. Kinda-sorta related, none of my 3 microburst encounters involved any obviously-nearby virga. So how close do you get? Channeling Dirty Harry...how lucky do you feel, punk? Bob W. --- This email has been checked for viruses by AVG. https://www.avg.com |
#18
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On Tuesday, September 1, 2020 at 11:19:22 AM UTC-7, ProfJ wrote:
Typing this with my fireproof suit on...last weekend I tried to duck between two rainy cumulus clouds on my glide back to home base. As I went through the gap it became filled with virga and I was sucked rapidly upwards, probably would have been about 10m/s if I had not had the nose well down. This was not tranquil, but not terrifying either (I was about 3000 ft below cloudbase) and added some useful height and speed. So here's the question: would you (do you?) deliberately head into virga if you needed the boost, or is this a truly dumb thing to do? Same for rain clouds (assuming you are in updraft not downdraft zone), how close would you get? Not looking for legal technicalities here, this was good VFR at all times - just trying to calibrate risk. What John and Matthew said. It's good advice. My rule is to pull spoilers if I have to go over 90 kts to avoid being sucked higher than comfortable. Big wings and cloud suck can get out of hand in a hurry. Even with spoilers out, there's no guarantee of staying out of the clouds. Give those big clouds the respect they deserve. Craig JN |
#19
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Some instructors don't think it's a big deal flying directly into IMC so......whatever.
(No, I'm not making this up and no, I don't mean a cloud. I'm instrument rated, I know wtf a cloud looks like and I mean no visible horizon, no view of the ground, no, I don' t mean in an aircraft certified for flight into IMC under IFR.) |
#20
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My experiences mirror that of others, in that much below the freezing level, virga is evaporating fast and causing an accelerating downdraft that sensibly you’d keep clear of. When the sky gets really big, airbrakes seem to be a very minor part of the equation, so the exit plan is best made before you get there.
Having said that, some of my longest and most fulfilling flights have been on days where the atmosphere feels like it’s boiling throughout its whole depth. All that energy... |
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