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#21
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On Thu, 25 Aug 2005 09:43:46 +0200, "Bert Willing"
wrote: Well, even if there is only one owner involved, I'm not going to rely on electrically power instruments only. Never.^ I still remember one competition back in 1991 when the US shut down GPS and suddenly a gaggle of 30 standard class gliders lost their navigation in the vicinity of Sobernheim (several airbases and restricted airspace there). I got to know a new definition of the term "confusion". Bye Andreas |
#22
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"Bill Daniels" wrote in message ... "Tim Ward" wrote in message ink.net... "Bill Daniels" wrote in message ... Does it strike some of the digerati here that expensive mechanical altimeters with easily mis-read clock-like hands locked into either the metric or US measurement systems are archaic? GPS provides highly accurate, although not ATC compliant, altitude. Various vendors provide electronic pressure altimeters with digital displays that can be switched between meters and feet with the push of a button. Digital pressure altitude sensors drive the "glass cockpits" of new GA aircraft. I seems to me that clock-like altimeters designed 70 years ago and maintained by watchmakers must be nearing their well-deserved retirement. Bill Daniels Yeah, now if they can just make them so they don't need batteries. Tim Ward What's the big deal with batteries? IMHO, batteries are at worst a minor inconvenience easily worth enduring for the benefits of the technology they make possible. Every portable gadget uses them. Most folks have a cell phone, PDA, portable GPS, digital camera, maybe a camcorder and who knows what else. Even your car, tug or winch won't start without a battery. They're cheap and they work fine with a little TLC and regular replacement. My glider uses a standard 7.5 AH 12V SLA that now sits on a shelf connected to a charger that quietly maintains the charge. I know for sure that it will work at least 10 hours and still show more than 12.5 volts while transmitting. It has a three year "replace by" date written on it whereupon I will plunk down $20 for another at "Batteries-R-Us" even if it still see ms OK. I don't trust old batteries. Bill Daniels Upon reflection, Bill, I'm sure that an instrument could be built that could satisfy both of us. Digital, easily scalable, there's no reason it can't have both an analog display (or quasi-analog, with LCD) for trends, and a 5 digit display for accuracy. It could have a lithium cell recharged by the expansion and contraction of an aneroid . Several "perpetual clocks" have used that scheme to drive mechanical gear trains with far smaller pressure changes than you'll get going up and down in a glider or airplane. An update rate of twice a second should be plenty fast enough. With LCDs, and CMOS circuitry running a few microamps at two volts or so, it's probably not impossible to build. You could probably build one with a primary lithium battery that would only need to be changed once every ten years or so. That would be the cheapest way to go. What will it cost to get it approved? How many people are going to buy it? In the small market that is aviation, what will it cost to build? If you could sell it cheaper than a mechanical altimeter, you might have a shot. In enough volume, you might be able to do that. I don't know if the altimeter market is large enough for that to be possible. The combined output of all the altimeter manufacturers is probably not as big as a run of, say, a cheap DVD player. I dunno. I'm afraid good enough is the enemy of best. If you don't care whether or not it's approved, or whether it takes batteries, then you should look at the Flytec hang glider varios. They have a lot of options as to what they display and how they display it, and I believe they'll display altitude both digitally and analog. They'd take up a bit more space on a panel, though. Tim Ward |
#23
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I have to fall firmly and loudly into the "digital is good, electrical
insturments can be reliable, mechanical varios belong in museums" group. I would love to see a serious study that shows that classic analog airspeed and altimeters (as used in gliders) are easier to read and less susceptible to misinterpretation than a properly designed (but unfortunately, theoretical) replacement digital airspeed and altimeter. With the advent of Head-up-Displays (HUDs), fighter planes have moved to almost completely digital displays of most values - only those where trend is crucial, such as vertical velocity and radar altitude, continue to have a companion analog display. Otherwise, its a straight number, usually rounded off to the nearest knot and 10 feet. Works fine in an F-15E, should work pretty good in an LS6 By comparison, trying to interpret a three-needle altimeter is like trying to read sanskrit! And then there are 1 1/2 revolution airspeed indicators! If you have a PDA in your cockpit, try setting it up to have a nice big font altitude (and speed, if available) display on it and try it - you might find that it is really easy to glance at and read. I have two seperated battery systems, and no mechanical vario. I'm stuck with a "steam-gauge" airspeed indicator and altimeter, but what I would really like is a digital airspeed, digital altimeter, and an accurate AOA indicator. For tradition, I'll keep the vario needles - since there I'm looking for trend (to provide a value to the audio), and read a digital averager for real decision making. Heck, last year I took off on a fine day only to find my airspeed inop (bug in the pitot) - but that didn't prevent me from flying a nice little 500+ k XC with some friends of mine. The only time I really missed the airspeed indicator was in the pattern. Just flew it a bit faster than usual (that AOA indicator sure would have been nice to have then...). Now the huge caveat - this is all fine in a private ship - I don't see how a the average club ship would manage. Kirk 66 |
#24
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#26
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At 22:06 24 August 2005, Ian Strachan wrote:
snip Bill Daniels wrote: snip GPS provides highly accurate, although not ATC compliant, altitude. I am afraid that the claim that GPS altitude is recorded 'highly accurately' in IGC files from IGC-approved GPS recorders, is unfortunately not true. This is not an attack on the accuracy of the GPS system or even its altitude recording capability. It is a reporting of results of GPS altitude recording in IGC flight data files derived from a number of low-cost GPS boards made by a number of different companies from different parts of the world. I guess that in more expensive 'professional aviation standard' GPS boards, and in differential-GPS systems with local beacons, the GPS altitude figures are more accurate and with less anomalies. But such (expensive) systems do not apply to the current 27 types of GNSS flight recorders that are IGC-approved (from 11 manufacturers) and whose IGC-approval documents appear on the IGC gliding/gnss web site: http://www.fai.org/gliding/gnss/igc_approved_frs.pdf The truth is that it is possible to record altitude very accurately with GPS, suyveyors who produce our maps use GPS both for lat/long and elevation with a resolution in height of less that 15mm over 10Km. Perhaps the reason that the manuafacturers mentioned above do not upgrade their equipment is that there is no demand as the IGC refuse to consider using GPS altitude. However good a baro recorder is it can never approach the accuracy of GPS. |
#27
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On Thu, 25 Aug 2005 21:02:37 +0100, Robin Birch wrote:
In message .com, writes I have to fall firmly and loudly into the "digital is good, electrical insturments can be reliable, mechanical varios belong in museums" group. Most of what we do flying we just want a trend or rough peak - analogue - say (in my personal opinion) thermal centering.For saying that a particular thing is better or good enough, say is that thermal good enough to stay with or is it falling off so we want to go to another, digital in the form of an averager is the absolute best. Agree 100% I really like the vario display on an SDI C4 and a Tasmin V1000 vario. Both use analogue for instant reading and digits for the averager. Both are easy to use. OTOH what are you doing looking at the vario in a thermal :-) I find the sound from a C4 makes centring very easy and all I look at is a glance at the averager from time to time to see if its time to leave the thermal yet. I very much like the idea of a B.40 as backup vario because it has its own internal battery and switch-over circuitry. I just wish it used an LCD analogue display rather than a needle for the instant rate display. -- martin@ | Martin Gregorie gregorie. | Essex, UK org | |
#28
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In message s, Martin
Gregorie writes On Thu, 25 Aug 2005 21:02:37 +0100, Robin Birch wrote: In message .com, writes I have to fall firmly and loudly into the "digital is good, electrical insturments can be reliable, mechanical varios belong in museums" group. Most of what we do flying we just want a trend or rough peak - analogue - say (in my personal opinion) thermal centering.For saying that a particular thing is better or good enough, say is that thermal good enough to stay with or is it falling off so we want to go to another, digital in the form of an averager is the absolute best. Agree 100% I really like the vario display on an SDI C4 and a Tasmin V1000 vario. Both use analogue for instant reading and digits for the averager. Both are easy to use. OTOH what are you doing looking at the vario in a thermal :-) Flying club K8s that I keep forgetting to put the battery in and so the mechanical is all I've got or my Astir when I've forgotten to charge them and they've gone flat on me after 4 hours :-)) I find the sound from a C4 makes centring very easy and all I look at is a glance at the averager from time to time to see if its time to leave the thermal yet. I very much like the idea of a B.40 as backup vario because it has its own internal battery and switch-over circuitry. I just wish it used an LCD analogue display rather than a needle for the instant rate display. -- Robin Birch |
#29
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Metric Instruments
On Wednesday, August 24, 2005 9:18:20 PM UTC+5:30, Roy Bourgeois wrote:
This may be a silly question - but are all metric altimeters configured with 'Zero at 6 O'clock' as I saw in France? I did not have trouble converting to meters/kilometers but I did have trouble quickly reading the altimeter with the zero at the bottom of the instrument face (especially on the little 57mm instruments). Just curious. Roy http://www.rlkswitches.com/ |
#30
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Metric Instruments
Hi Roy,
That is very common. It is the standard. I suppose it is similar to most industrial gauges which have the zero at the bottom. Best Regards, Paul Remde Cumulus Soaring, Inc. __________________________________________ wrote in message ... On Wednesday, August 24, 2005 9:18:20 PM UTC+5:30, Roy Bourgeois wrote: This may be a silly question - but are all metric altimeters configured with 'Zero at 6 O'clock' as I saw in France? I did not have trouble converting to meters/kilometers but I did have trouble quickly reading the altimeter with the zero at the bottom of the instrument face (especially on the little 57mm instruments). Just curious. Roy http://www.rlkswitches.com/ |
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