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#81
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Bruce Hoult wrote:
In article , "Pete Reinhart" wrote: Mark, A most thoughtful metric. It might lead to a very interesting way of valueing the gider market as opposed to $perL/D. Of course this is just L/D at 80 knots, with his 300 fpm cutoff being an L/D of about 26.6:1 and an LS4 being 25:1. It appears that you need (-ve) flaps to get as low as 300 fpm, but then there are lots of missing interesting gliders. The Discus and ASW28 may prove me wrong, for example. Getting lower fpms seems to also have at least one downside too: higher stall speed. I personally would like something like a Russia AC-4c, with a fairly low stall speed, but with ballast too. Short wings and slow stall speed when I want it are good. I wonder about getting one with a motor and then just putting a big water bag in the hatch instead 30 knot stall vs. 40 knot stall is 900 vs. 1600 energy units at landing. Almost twice as much energy to dissapate at touchdown. Once the unballasted stall speed of a glider gets past 40 knots, I'd be a little hesitant to be "happy' about the great penetration... -- ------------+ Mark J. Boyd |
#82
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Mark James Boyd wrote:
Getting lower fpms seems to also have at least one downside too: higher stall speed. I personally would like something like a Russia AC-4c, with a fairly low stall speed, but with ballast too. Short wings and slow stall speed when I want it are good. I wonder about getting one with a motor and then just putting a big water bag in the hatch instead 30 knot stall vs. 40 knot stall is 900 vs. 1600 energy units at landing. Almost twice as much energy to dissapate at touchdown. Your arithmetic is right, but the Russia stalls closer to 40 knots than 30 knots at the weight I flew one several years ago (180 pounds with parachute). It landed noticeably faster than a Blanik or PW5. Once the unballasted stall speed of a glider gets past 40 knots, I'd be a little hesitant to be "happy' about the great penetration... There is a world of difference landing off field with a glider that touches down at 30 knots vs 40. I've known pilots that got spooked by the faster landings when they moved from slower speed gliders to a "high performance" one. Landing in a field just didn't seem like a such a good idea anymore. Training can overcome this, but some just quietly slipped away from the sport. -- Change "netto" to "net" to email me directly Eric Greenwell Washington State USA |
#83
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Bruce Greeff wrote:
I fully plan to trade my 1971 Std Cirrus in the moment I am a better pilot than it is a glider... May take a looong time. I know you are talking about performance, but let me suggest you are wrong anyway. If you are a decent pilot, you are already better overall than a 35 year old design; if you AREN'T a decent pilot, you really would benefit from a better glider! The newer gliders, as John Cochrane pointed out in a recent post, handle better (more pleasant and safer to fly), usually have automatic hookups, and offer much more pilot protection if the first two aren't sufficient. Speaking as a former owner of Std Cirrus ... unless you don't have much money, the twitchiness over 70 knots, poor stall and spin characteristics, the poor airbrakes, and the poor wheel brake, don't add up to a glider you should have any loyalty to when there are so many better choices nowadays. Try a better glider - "better" isn't just about L/D - even a 20 year old design like an LS4 is a distinct improvement. -- Change "netto" to "net" to email me directly Eric Greenwell Washington State USA |
#84
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Eric Greenwell wrote:
Bruce Greeff wrote: I fully plan to trade my 1971 Std Cirrus in the moment I am a better pilot than it is a glider... May take a looong time. I know you are talking about performance, but let me suggest you are wrong anyway. If you are a decent pilot, you are already better overall than a 35 year old design; if you AREN'T a decent pilot, you really would benefit from a better glider! The newer gliders, as John Cochrane pointed out in a recent post, handle better (more pleasant and safer to fly), usually have automatic hookups, and offer much more pilot protection if the first two aren't sufficient. Speaking as a former owner of Std Cirrus ... unless you don't have much money, the twitchiness over 70 knots, poor stall and spin characteristics, the poor airbrakes, and the poor wheel brake, don't add up to a glider you should have any loyalty to when there are so many better choices nowadays. Try a better glider - "better" isn't just about L/D - even a 20 year old design like an LS4 is a distinct improvement. Hi Eric I tend to agree that one can always benefit from better equipment, irrespective of capability. As long as the skill demands of the new equipment remains within your capabilities. Failing which, it is worse, for you. My point is that the primary limitation in most cockpits is the capability of the nut on the stick, rather than the structure the stick is part of. So - I am a reasonable pilot I guess, and able to push the Cirrus sometimes. My point was that for the money, and considering the available fleet in my part of the world, I have a pretty satisfactory toy for my relatively undeveloped capabilities. I would love to buy a higher performance/more forgiving etc./newer airplane, but I am not forgetting to enjoy and USE what I have. Consider, the Cirrus has generally sweet handling, works well in our generally strong conditions and is teaching me a lot about XC with very low financial risk. Sure I have to accomodate the characteristics of the aircraft - the wheel brake is worse than the airbrake, which is not the most powerful ever met. (so I learn to plan carefully for outlandings) The controls are very sensitive in pitch , especially at high speed (so I learn precision - this is good) She is not particularly fast, so I learn to make the most of the soaring time available. Given that I do not have unlimited funds available, I think it is better for me to spend as much time flying my cheap to own, and quite capable 1970s design. My evaluation is that the quantum of experience/time/launches will benefit me far more than being able to just afford to fly, once a month in a one generation newer plane, or not at all in a brand new supership... If funds were no limit I would be flying more, and working less ;-) irrespective of the mount. I would also benefit from a better glider, all other things being equal, and I suspect this applies to most. |
#85
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Eric Greenwell wrote:
Mark James Boyd wrote: 30 knot stall vs. 40 knot stall is 900 vs. 1600 energy units at landing. Almost twice as much energy to dissapate at touchdown. Your arithmetic is right, but the Russia stalls closer to 40 knots than 30 knots at the weight I flew one several years ago (180 pounds with parachute). It landed noticeably faster than a Blanik or PW5. Not fair! The Blanik has (fowler?) flaps! :P But yes, the PW-5 was noticably slower on landing. What's really amazing is the Sparrowhawk. Look at the penetration and then look at the low stall speed. And fixed gear? Amazing... I haven't flown one yet (and I missed my chance at the Labor Day weekend at Tehachapi) but I drool... Once the unballasted stall speed of a glider gets past 40 knots, I'd be a little hesitant to be "happy' about the great penetration... There is a world of difference landing off field with a glider that touches down at 30 knots vs 40. I've known pilots that got spooked by the faster landings when they moved from slower speed gliders to a "high performance" one. Landing in a field just didn't seem like a such a good idea anymore. Agreed completely. $30k worth of glider with twice as much energy to dissipate over ruts or rocks or a caught wing is a lot more $$$$$ of damage. I honestly think with the excellent harnesses and cockpit energy absorption of modern aircraft (15 years old or less), anything landing/stalling nearly level below 40 knots will result in minor injuries, at most. But $$$$$s of damage? That's a different story... Carl Herold has words about this. I suspect his conservatism in outlandings is directly proportional to the $$$$s of glider he's piloting. Makes the cheapo 1-26 look pretty sweet, eh? :PPPPP -- ------------+ Mark J. Boyd |
#86
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