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#231
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New Butterfly Vario
I have an old J-8 gyro attitude indicator and a static inverter to feed it
400 cps AC (yup, it was cycles per second before they bestowed the honor on Prof. Hertz). I'd mount it in my panel but it takes a large hole (80 mm?) and the weight would probably put my CG past the forward limit or, as a minimum, break my carbon panel. It's also a totally black sphere except for the yellow "targets" at the plus and minus 90 degree pitch attitude points, and there's a yellow horizon line which moves independently of the sphere, and a yellow airplane symbol. It's probably radio active with radium paint and, therefore, probably illegal even to own (do I hear black helicopters?). Somebody make me an offer. It works, but I don't know how much current it draws... Also, it's so old that most people wouldn't even think that it works and, therefore, wouldn't think to protest its presence in the panel. This is a full-fledged mil-spec attitude indicator, not a wimpy turn indicator... "Eric Greenwell" wrote in message ... On 2/17/2012 8:07 PM, Sean Fidler wrote: Tom, Why do any gliders have gyro's at all? 40 years ago, almost nobody did, because they were expensive ($1000 for an AH when gliders cost $20,000), drew an amp, and were big and heavy, and most people didn't have a real use for it. Now, they they are cheap ($500 when gliders cost $100,000), use very little current, and are small and light, so even though people don't have any greater use for it than 40 years ago, they like the look of it and think it might help some day. Some power pilots seem to feel naked without them, having had one for hundreds or thousands of hours in their airplanes. I used to have a gyro T&B in my panel, because I got it dirt cheap, and it looked prettier than the empty hole in the panel. I thought, maybe some day I'll get stupid or have some really bad luck, and maybe it would help me descend through a wave cloud that closed in. I never worried about being sucked into a cloud, though. And some people use them to cloud fly, illegally and legally. -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me) |
#232
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New Butterfly Vario
At 16:15 18 February 2012, Dan Marotta wrote:
Chris, I'm going to try to analyze the height trace using the graphical functions in Microsoft Excel. I'll look for a sudden increase in rate of climb and make a guess from there. I might say in advance that I'm not hopeful, but this should be a fun exercise. Dan Dan, I do quite a lot of cloud flying mostly to keep current as cloud flying is allowed in UK competition and sometimes it is necessary to fly in cloud to stay up. However....it rarely is faster. I usually find that my climb rate drops as I enter cloud because the artificial horizon although good is not anything like as good as the real thing. In my experience if cloud base allows it is much faster to fly the energy below cloud. BTW I also find cloud flying fun which is after all the reason I go flying. J1M |
#233
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New Butterfly Vario
Well, just going on a look-see, it looks like cloud base in one of the
traces was around 17,200 MSL with a top of climb of 24,740 MSL and, in the other, around 16,000 MSL with a top of climb of 34,480. So... How'd I do? I'm also thinking that your altitudes might be in meters and if that's the case, then it might be... Cloud Base: 1,720 meters, Top of climb: 2,447 meters for the first flight, and, for the second, Cloud Base: 1,600 meters, Top of climb: 3448 meters. Since I can't paste a picture in here, I sent you the Excel file with the traces included on Sheet 3. Please let us know if such a quick look came close. "Dan Marotta" wrote in message ... Chris, I'm going to try to analyze the height trace using the graphical functions in Microsoft Excel. I'll look for a sudden increase in rate of climb and make a guess from there. I might say in advance that I'm not hopeful, but this should be a fun exercise. Dan BTW, I received your IGC files. "Chris Nicholas" wrote in message ... Dan, see your emails. Regards - Chris |
#234
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New Butterfly Vario
Dan was about right. Using metres is more like right – the plots Dan
sent me showed way too many feet on the left hand scale. My recollection is that cloudbase was a bit over 4000 feet and I climbed to about 11000 feet that day. By the way, to repeat part of what I sent Dan privately - I do not claim to be a very good IMC pilot. I had a bit of instruction at first, then a lot of self-learning in a Ka6E which is strong, draggy, has speed-limiting brakes/spoilers, and is fairly forgiving when things go wrong – which they often did when I was slowly acquiring the skill, using only a glider Turn and Slip (stronger spring, less sensitive than a Power T&S so it does not go onto the stop in a thermalling turn). I also advise other people not to cloud fly. Modern gliders are too slippery to self-teach safely, IMHO. I do it because I like it and accept the risk (which I think is minimal having learned the slow way). I also agree with Jim's comments. Chris N. |
#235
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New Butterfly Vario
Thanks to Chris who took the time to look up the IGC specification for the
log file. From his analysis, I was able to determine that the cloud base on one of the flights was around 5,200 ft (lower than my airport!). The trace looked the same, just the altitude scale was changed. And it's interesting what Jim said about reduced lift inside the cloud. I would have expected higher lift due to the heat release. Maybe that's all expended right at cloud base... It was a fun exercise! "Dan Marotta" wrote in message ... Well, just going on a look-see, it looks like cloud base in one of the traces was around 17,200 MSL with a top of climb of 24,740 MSL and, in the other, around 16,000 MSL with a top of climb of 34,480. So... How'd I do? I'm also thinking that your altitudes might be in meters and if that's the case, then it might be... Cloud Base: 1,720 meters, Top of climb: 2,447 meters for the first flight, and, for the second, Cloud Base: 1,600 meters, Top of climb: 3448 meters. Since I can't paste a picture in here, I sent you the Excel file with the traces included on Sheet 3. Please let us know if such a quick look came close. "Dan Marotta" wrote in message ... Chris, I'm going to try to analyze the height trace using the graphical functions in Microsoft Excel. I'll look for a sudden increase in rate of climb and make a guess from there. I might say in advance that I'm not hopeful, but this should be a fun exercise. Dan BTW, I received your IGC files. "Chris Nicholas" wrote in message ... Dan, see your emails. Regards - Chris |
#236
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New Butterfly Vario
In my experience lift in cloud is stronger only if the cloud has a lot
of vertical development – say several thousand feet, which of course developing CBs do have, and provided you can stay centred in the lift, which as Jim points out is harder if you can’t see the real horizon. I have found that expanding the GPS scale helps a lot in keeping in good lift, in VMC or in IMC. (I still do not advocate people teaching themselves to do the latter these days – if it goes wrong in a slippery glider, it can do so very quickly and very badly.) In the more usual “good” conditions in the UK when we get them, an inversion stops vertical cu development and they are often only a few hundred or 1-2000 feet deep. Then, as Jim says, it is usually faster to keep in the energy where you can see it, in VMC. With very shallow clouds, it is not even worth going up to cloud base – the lift weakens before getting there. Even if it does strengthen briefly at and into cloud, I usually lose more in the fumble of coming out on the wrong heading, or on the right one but into another cloud and in its sink, than staying below, if achieved speed is what you are after. Chris N |
#237
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New Butterfly Vario
On Feb 19, 10:12*am, Chris Nicholas wrote:
In my experience lift in cloud is stronger only if the cloud has a lot of vertical development – say several thousand feet, which of course developing CBs do have, and provided you can stay centred in the lift, which as Jim points out is harder if you can’t see the real horizon. I have found that expanding the GPS scale helps a lot in keeping in good lift, in VMC or in IMC. (I still do not advocate people teaching themselves to do the latter these days – if it goes wrong in a slippery glider, it can do so very quickly and very badly.) In the more usual “good” conditions in the UK when we get them, an inversion stops vertical cu development and they are often only a few hundred or 1-2000 feet deep. Then, as Jim says, it is usually faster to keep in the energy where you can see it, in VMC. With very shallow clouds, it is not even worth going up to cloud base – the lift weakens before getting there. Even if it does strengthen briefly at and into cloud, I usually lose more in the fumble of coming out on the wrong heading, or on the right one but into another cloud and in its sink, than staying below, if achieved speed is what you are after. Chris N It is very common in Arizona to have at least a slight inversion at or below cloud base. What happens in these cases is that the rising airmass in a strong thermal continues going up under its own momentum. It's not uncommon in these circumstance to find the lift cutting off a thousand feet below the clouds and very nice looking clouds have no lift under them. I sometimes refer to these clouds as resulting from the last dying gasp of a rising thermal! With instability of the atmosphere rising above cloud base, thermals will often increase with strength as you approach the cloud and this increase continues into the cloud. These are the circumstances when you might get too close to the cloud - it's not uncommon here to find a ten-knot thermal strengthening to 12 to 15 knots! At these vertical speeds, you can go from a safe distance below into cloud in about half a turn. It's very easy to do and a not uncommon experience out west. Mike |
#238
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New Butterfly Vario
VG post by Andy Gough.
This debate has been going on since the '60s! AH s and T and S had to be removed for constests outside the UK ( and Yugoslavia etc) but then the Bohli compass appeared which confused the issue. I personally proved to myself that I could manage for a while using a COOK compass, predecessor of the Bohli. Cloud climb with only ASI and vario! Wow. I would not try that in a modern ship. The GPS record should take care of transgressions, but wave either lee o thermal ,poses a problem. John Firth |
#239
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New Butterfly Vario
Whatever. Time to go flying. Moving on.
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