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#11
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Netto
On 1 août, 18:24, Martin Gregorie
wrote: On Mon, 01 Aug 2011 13:18:02 -0600, BobW wrote: A few 'weird Libelle pilots' (and myself) aside, most glider cockpits I've seen have (at least!) two varios, so I suppose a person might argue that - when I still had the Ball in place - I was using two varios to do what the C4 (with which I'm 100% ignorant) implements in a single unit...save for the fact it 'continually subtracts' that aforementioned 200 fpm/2 knots when in cruise mode. I'm also a Libelle driver, though of the two vario variety: I carry a Borgelt B.40 as backup to the C4 and fins its extremely rapid response is a useful addition to the C4, especially for finding the hot spots under large clouds. * I've wondered why the C4 uses super netto rather than plain netto in cruise mode. My current best guess is that maybe the switch from netto to TE modes causes the vario to step its reading. The C4 never produces a sudden reading change that I've noticed when it switches between modes. Anyhow, returning to the O.P.'s O.Q. (original question), my vote would be to use 'unadjectivized "Netto"' for at least a couple of 'longish soaring flights' or until such time as what I've tried to describe makes conceptual/in-flight sense. Agreed. I suggest the OP does a few flights with each netto setting, *in each case staying with the same netto type long enough to get used to what its telling him in cruise mode. Then he should simply use the one he likes best. -- martin@ * | Martin Gregorie gregorie. | Essex, UK org * * * | Thank you for your for your answer. The owner manuel says; netto is what the airmass is doing, relative vario is what you would get if you stop for thermaling. After 50 hours with netto I will try relative netto for a while. The best of lift. S6 |
#12
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Netto
On Jul 29, 7:05*pm, BobW wrote:
On 7/29/2011 11:19 AM, bish wrote: Hi This question has probably been ask many time! My new to me LX 7000 offer the choice of Netto or Relative netto for the vario needle. Why should I choose one or the other? Or which is most usefull? Thank you S6 Uh oh...one of those 'religious questions' on RAS. Everyone tighten your seatbelts! Disclaimer: I have absolutely Zero Experience/Exposure to an LX 7000. The rest of this comes from a pilot having flown only w. a(n excellent) mechanical netto display since 1981. Further - displaying additional ignorance here - I'll admit to being uncertain what 'relative netto' actually is or means. That noted, after being exposed to *netto* 'way back when' and pondering on it briefly, my brain asked itself the question, "What more do I need or want to know than what the air is actually doing?" From that single piece of information, everything else I - as Joe Glider Pilot - might *want* to do becomes immediately obvious. Assuming your ship has decent speed compensation, a netto display instantly: 1) lets you accurately conclude if the air through which you're flying is 'climbworthy,' and 2) (when combined with a good, old-fashioned, speed-to-fly ring, set as desired for the day in question, and, flying in descending air) instantly/continuously points to the correct speed to fly, in a non-iterative manner. Non-netto mechanical displays with which I'm familiar, achieve these two things only via indirect/iterative means, IMHO. Joe Pilot has to do considerably more mental work/instrument-gazing with a non-netto display. All bets may be off with electronic?microprocessor-based indicators...though just because something is electronic is no guarantee of 'new-&-improved' or 'simpler' or 'better' information display, in my experience. To my way of thinking (being a simple kind of guy), an analog-displayed netto (whether achieved mechanically or electronically), combined with a speed ring, is simple and intuitive, and not obviously improved upon. (I'm aware of how useful a well-implemented audio can be...) Downsides? 1) You'll get 'somewhat bogus' information on tow, due to the influence of the towplane's added energy...truly a minor deal to me. Certainly it never hampered/bothered my "OK to release?" decision, since the first few moments of towed flight - regardless of towplane or situation - quickly allows determination of that particular tow combination's steady state netto indication, hence anything above that is lift, of immediately known strength. 2) Some don't like not 'knowing' the actual climb rate when climbing, since the needle displays air vertical motion, not glider vertical motion. Never having had difficulty subtracting 200 from a needle indication, it never bothered me. Besides, having begun soaring in the days before electronics, I quickly developed the habit of timing my actual rate of climb (sweep second hand and altimeter) anyway, from which I concluded most people were hopeless optimists when it came to reporting *their* climb rates. Use what works best for how your mind works, and go have fun! Regards, Bob W. P.S. Kinda-sorta related, don't lose sleep over errors inherent in 'polar uncertainties' (e.g. ballast or not, circling or not). From Joe Average Pilot's perspective. this sort of 'stuff' is in the noise level compared to the lift/sink strengths on which you'll be basing your 'thermic day' flight decisions. Slightly OT, but do you fly without an audio? THAT is scary! Especially, if you are staring at a stopwatch and altimeter, trying to figure out what your climb rate is, and watch the vario needle to center the thermal. Doesn't leave much time for looking out the window... The beauty of modern gizmos is that they do all that "stuff" for you, and let you concentrate on what is going on outside the cockpit, where there be dragons! As far as Relative (or Super) Netto, it just takes one more bit of math out of the cockpit - just like regular netto takes some math out compared to plain old TE. So, I'm cruising along, waiting for a 5 knot thermal to climb in. With a regular Netto, I've got to wait for a 7 knotter. With relative, I just wait until I see 5 knots, and up we go! Truthfully, I've tried both, and kinda prefer plain old netto, especially when running under cloud streets... Cheers! Kirk 66 |
#13
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Netto
On 8/2/2011 11:56 AM, kirk.stant wrote:
Major snip... Slightly OT, but do you fly without an audio? Probably more than 50% of the time. Learned that way, have had ships with and without audio, and find it useful and a convenience, but far from 'life-or-death crucial.' For that matter, having: 1) flown (including thermal-XC) without functioning vario (several times...usually from water in the plumbing); 2) flown (thermal XC again) without functioning ASI (intermittent 'T/U' on a series of XC flights before 'indubitable death'); and 3) flown (once, thermal XC again) w/o vario *and* ASI (water, again), I've found the first two conditions are pretty much non-events, while the last combination took maybe 15 minutes or so to get accustomed to, but one's butt and ears are actually quite sensitive if you pay attention to 'em. The butt in particular is really good at detecting vertical acceleration *changes* which - if Joe Glider Pilot learns to pay effective attention to it/'em - is far quicker than any vario, which displays motion only after it has occurred, no matter how short the vario's time constant. THAT is scary! Why? Especially, if you are staring at a stopwatch and altimeter, trying to figure out what your climb rate is, and watch the vario needle to center the thermal. Doesn't leave much time for looking out the window... Ah! Who said anything about 'staring'? Peripheral vision works quite well for noting (say) vertical passage of a sweep second hand and progression of an altimeter hand on routine panel scans. (Anyone who thinks measuring a climb rate over less than 30 seconds is 'XC valid' is indulging in self-deception; I happen to prefer 60 seconds as 'more honest.' In any event, it's probably the rare glider pilot who doesn't scan SOMEthing on the panel once or twice a minute. Time yourself some time!) Furthermore, my instructor pithily noted, "Staring at the instruments doesn't make you climb any faster." He further noted, "Besides, climbing after a mid-air collision is generally impossible." Both droll understatements made perfectly good sense to me, even if I had NOT paid very close attention to listening to and learning from what he sought to convey to me. The beauty of modern gizmos is that they do all that "stuff" for you, and let you concentrate on what is going on outside the cockpit, where there be dragons! Agreed on both counts, but especially the 'dragons' bit. Situational awareness is the key. That's true not 'merely' in sailplanes. Consider the drive to and from the gliderport...I don't - in the absence of a functioning speedometer - have any trouble driving a vehicle with which I'm 'a few drives worth' familiar and remaining speeding-ticket-free. BTDT in lots of vehicles, from cars to big rigs to buses over the years. 'Ear calibration' is real. Situational awareness is real. Practice ought not to be only a sometime event. Of course, I'm not about to claim ear/butt calibration is as precise/effective as 'the latest-n-greatest instrumentation,' but I hope the point that - at least in the intermountain west on any averagely decent day for a 'moderately experienced' sailplane pilot - 'modern gizmos' while usefully enabling, are far from absolutely necessary. Cat-skinning remains a multi-method activity. As far as Relative (or Super) Netto, it just takes one more bit of math out of the cockpit - just like regular netto takes some math out compared to plain old TE. Granted, but you don't get it 'for free.' The instrument designer is making an educated guess as to your ship's 'circling sink rate increment.' Presuming curiosity, Joe Pilot's own tests may disagree with the designer's guess. But more to the point, is it *really* so difficult to always subtract 2 knots from a glanced-at instrument reading? As non-mathematical a mind as is mine, that subtraction quickly became second nature for me. This is one case where I find the raw data more rapidly comprehensible/useful than massaged data. Cat-skinning, again... So, I'm cruising along, waiting for a 5 knot thermal to climb in. With a regular Netto, I've got to wait for a 7 knotter. With relative, I just wait until I see 5 knots, and up we go! Truthfully, I've tried both, and kinda prefer plain old netto, especially when running under cloud streets... Cheers! Kirk 66 Regards, Bob - no harm, no foul? - W |
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