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#71
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In article ,
Eric Greenwell wrote: Mark James Boyd wrote: Where's the stall warning horn? I'm still utterly baffled why there isn't a stall warning device on each wingtip? Is this really that much extra drag? Is it more drag than that caused by having to make a wing design that buffets before a full stall? It might be useful to look at small airplane accidents, since they DO have stall warning horns. I'm under the impression that stall/spin accidents are a big cause of fatal accidents also. Do you have any numbers? I looked up the last ten years of gliders (49 fatalities) and then I looked up a three month window of airplane fatalities from 3/94 to 6/94 (102 fatalities). I got lazy and didn't want to look through more than 100, but I wanted to see final reports, so... Gliders: 21 stalls of 49 fatalities = 43% If you eliminate midairs and disconnected controls, 21 of 42 = 50% Airplanes: 9 stalls of 102 fatalities = 9% If you eliminate midairs and disconnected controls, 9 of 91 = 10% A bunch of the airplane ones were also night and/or IFR (less than half). But it seemed real clear that more of the glider fatalities could have been stalls. Anyway, I concluded that airplane guys don't stall very much close to the ground... I was also VERY surprised to find a lot of medical problems with airplenes, and I don't think even one fatal glider accident due to a medical condition. This is really surprising...I'll need to look at all 250 fatal glider reports at some point to see if there are ANY medical fatalities... Anyway, yes glider pilots die from stalls as a real big factor. I think it's because they don't have warning devices. Hells bells, just hook 'em to the gear down and spoiler cracked switches, so they're off the rest of the time (thermalling). Or maybe somebody has a better idea. I dunno, I'm just real surprised we don't have any stall horns at all on any gliders... -- ------------+ Mark Boyd Avenal, California, USA |
#72
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In article ,
Jack wrote: On 3/12/04 2:05 PM, in article 40521816$1@darkstar, "Mark James Boyd" wrote: Where's the stall warning horn? On the Cessna, where it belongs. Don't even think about putting one in a sailplane. Soaring ought to be about flying the aircraft, not just monitoring the government-mandated distractions. The thing would either be activated during most thermaling, or have such a close tolerance as to give no useful warning to those who would most need it -- and they are expensive. Would you recommend flashing lights on the panel, a speaker tone to compete with the vario, or both? Perhaps you would also like to incorporate a stick-shaker? Who said anything about the gubmint? And what would I want with a vario during the landing phase, off-field or not? If I've got the gear down and the spoilers out, I'd be playing the fool to try using the vario for anything... Have the vario shut itself off and let the stall warning buzzer on... Expensive? I couldn't comment on that...And are the fatal accidents so rare as to make this idea pointless? Perhaps... As far as spoilers and flaps changing the stall speed, I suppose that's glider dependent on how much. And as far as bugs, again I don't know how far off the normal stall speed you'd see... Maybe it's negligible, maybe not. Dunno... -- ------------+ Mark Boyd Avenal, California, USA |
#73
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In article ,
Eric Greenwell wrote: Andreas Maurer wrote: On 12 Mar 2004 12:05:42 -0800, (Mark James Boyd) wrote: Where's the stall warning horn? I'm still utterly baffled why there isn't a stall warning device on each wingtip? Is this really that much extra drag? Is it more drag than that caused by having to make a wing design that buffets before a full stall? There are gliders that are equipped with stall audio warnings. Most of these stall warnings have been switched off permanently because they were yelling all the time while thermalling. THe difficulty is getting a true stall warning, rather than an airpeed alert (even if it is adjusted to G loading). Other difficulties with the type Andreas mentions is it doesn't know when the spoilers are out, the flap position, or the bugs on the leading edge. Well, on Cezznas and others, it's just a dorky cheap little tab which is at the right angle to flip up and close a circuit when the AOA is pretty close to stall. The Beech Duchess has 2, one for not so much flaps (on one wing), one for lotsa flaps (on the other wing). I guess I'm not even that surprised they aren't on nost sailplanes, I'm interested to know of the folks who've built their own, have you guys thought of trying it? Man I'd love to know what them wingtips are doing... -- ------------+ Mark Boyd Avenal, California, USA |
#74
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Mark James Boyd wrote:
It might be useful to look at small airplane accidents, since they DO have stall warning horns. I'm under the impression that stall/spin accidents are a big cause of fatal accidents also. Do you have any numbers? I looked up the last ten years of gliders (49 fatalities) and then I looked up a three month window of airplane fatalities from 3/94 to 6/94 (102 fatalities). I got lazy and didn't want to look through more than 100, but I wanted to see final reports, so... Gliders: 21 stalls of 49 fatalities = 43% If you eliminate midairs and disconnected controls, 21 of 42 = 50% Airplanes: 9 stalls of 102 fatalities = 9% If you eliminate midairs and disconnected controls, 9 of 91 = 10% A bunch of the airplane ones were also night and/or IFR (less than half). But it seemed real clear that more of the glider fatalities could have been stalls. Anyway, I concluded that airplane guys don't stall very much close to the ground... I was also VERY surprised to find a lot of medical problems with airplenes, and I don't think even one fatal glider accident due to a medical condition. This is really surprising...I'll need to look at all 250 fatal glider reports at some point to see if there are ANY medical fatalities... Anyway, yes glider pilots die from stalls as a real big factor. I think it's because they don't have warning devices. Hells bells, just hook 'em to the gear down and spoiler cracked switches, so they're off the rest of the time (thermalling). Or maybe somebody has a better idea. I dunno, I'm just real surprised we don't have any stall horns at all on any gliders... I'm not suggesting this isn't a good idea, but I do wonder... Why do airplanes have ANY stall/spins during landing? Typically, they have full control of their pattern (altitude, entry point), while the glider accidents most often occur when the pilot can't do the desired pattern because he returns too low. Maybe we don't need a stall warning for gliders: perhaps a simple airspeed alert would do everything that is needed, as long as it was enabled by the gear being extended. I think it should alert regardless of the spoiler position, since a low, slow pilot isn't likely to open the spoilers. DG sailplanes makes such a device, called the DSI. Take a look he http://www.dg-flugzeugbau.de/dsi-e.html DG Flugzeugbau GmbH / DSI - Digital Soaring Indicator Is anyone using one of these? Maybe we already have what we need, but not enough people are using it. -- ----- change "netto" to "net" to email me directly Eric Greenwell Washington State USA |
#75
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Mark James Boyd wrote:
Soaring ought to be about flying the aircraft, not just monitoring the government-mandated distractions. The thing would either be activated during most thermaling, or have such a close tolerance as to give no useful warning to those who would most need it -- and they are expensive. Would you recommend flashing lights on the panel, a speaker tone to compete with the vario, or both? Perhaps you would also like to incorporate a stick-shaker? Who said anything about the gubmint? And what would I want with a vario during the landing phase, off-field or not? If I've got the gear down and the spoilers out, I'd be playing the fool to try using the vario for anything... Have the vario shut itself off and let the stall warning buzzer on... Expensive? I couldn't comment on that...And are the fatal accidents so rare as to make this idea pointless? Perhaps... As far as spoilers and flaps changing the stall speed, I suppose that's glider dependent on how much. And as far as bugs, again I don't know how far off the normal stall speed you'd see... Maybe it's negligible, maybe not. Dunno... Some varios, like the Cambridge 302, already have gear warning, spoiler unlocked on takeoff warning, and airspeed alert built into them. It even adjusts for G loading. I suspect it would be a simple change to it's software to have two airspeed alerts, based on gear position: Gear up (soaring): set it a little below normal thermalling speed (about 46 knot setting works on my glider with my 302). Gear down (landing): set it a little below the typical pattern speed (about 50 knots would work on my glider). -- ----- change "netto" to "net" to email me directly Eric Greenwell Washington State USA |
#76
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"Eric Greenwell" wrote in message ... DG sailplanes makes such a device, called the DSI. Take a look he http://www.dg-flugzeugbau.de/dsi-e.html DG Flugzeugbau GmbH / DSI - Digital Soaring Indicator Is anyone using one of these? Maybe we already have what we need, but not enough people are using it. -- ----- change "netto" to "net" to email me directly Eric Greenwell Washington State USA Interesting device but maybe a little too much feature bloat. It wasn't clear to me that different minimum airspeed warnings could be set for various glider configurations such as, say, 55Kts with the gear down but 42 knots with the gear up. doesn't really matter - I'd settle for just a differential pressure switch that is set once and interlocked with the gear. The "Dolly Warning" is interesting. Just place a magnetic reed switch inside the tail boom where the dolly fits and bolt a strong magnet on the dolly. 900 Euro is probably cheap compared to the mayhem it is intended to prevent but I'd bet that an equivalent device could soldered up for a lot less by an electronics hobbyist. Bill Daniels |
#77
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In article ,
Eric Greenwell wrote: Mark James Boyd wrote: It might be useful to look at small airplane accidents, since they DO have stall warning horns. I'm under the impression that stall/spin accidents are a big cause of fatal accidents also. Do you have any numbers? I looked up the last ten years of gliders (49 fatalities) and then I looked up a three month window of airplane fatalities from 3/94 to 6/94 (102 fatalities). I got lazy and didn't want to look through more than 100, but I wanted to see final reports, so... Gliders: 21 stalls of 49 fatalities = 43% If you eliminate midairs and disconnected controls, 21 of 42 = 50% Airplanes: 9 stalls of 102 fatalities = 9% If you eliminate midairs and disconnected controls, 9 of 91 = 10% A bunch of the airplane ones were also night and/or IFR (less than half). But it seemed real clear that more of the glider fatalities could have been stalls. Anyway, I concluded that airplane guys don't stall very much close to the ground... I was also VERY surprised to find a lot of medical problems with airplenes, and I don't think even one fatal glider accident due to a medical condition. This is really surprising...I'll need to look at all 250 fatal glider reports at some point to see if there are ANY medical fatalities... Anyway, yes glider pilots die from stalls as a real big factor. I think it's because they don't have warning devices. Hells bells, just hook 'em to the gear down and spoiler cracked switches, so they're off the rest of the time (thermalling). Or maybe somebody has a better idea. I dunno, I'm just real surprised we don't have any stall horns at all on any gliders... I'm not suggesting this isn't a good idea, but I do wonder... Why do airplanes have ANY stall/spins during landing? Typically, they have full control of their pattern (altitude, entry point), while the glider accidents most often occur when the pilot can't do the desired pattern because he returns too low. Maybe we don't need a stall warning for gliders: perhaps a simple airspeed alert would do everything that is needed, as long as it was enabled by the gear being extended. I think it should alert regardless of the spoiler position, since a low, slow pilot isn't likely to open the spoilers. DG sailplanes makes such a device, called the DSI. Take a look he http://www.dg-flugzeugbau.de/dsi-e.html DG Flugzeugbau GmbH / DSI - Digital Soaring Indicator Is anyone using one of these? Maybe we already have what we need, but not enough people are using it. Well, some of the power accidents are just newer pilots that weren't trained to properly react to the horn. In some I suspect the horn wasn't even working (I've been surprised by failed horn a few times). The airspeed idea is good (better than nothing) but doesn't tell the AOA at both wingtips, and doesn't seem to account for the G loading in a tight turn. Also, as another poster pointed out, the horn detects gusts, which is pretty useful IMHO. In any case, I'd just love to have a glider with an AOA tab (each with a different tone) on each wingtip, and teach some spins in it. I'd also love to see how well it does when thermalling. Maybe Andreas is right and one can't tell horn vs. vario, but it would be a kick to try... Anyway, just another fun idea...now let's cut out this nonsense and get back to implementing the turbine powered sparrowhawk ;P -- ------------+ Mark Boyd Avenal, California, USA |
#78
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Mark James Boyd wrote:
Well, some of the power accidents are just newer pilots that weren't trained to properly react to the horn. In some I suspect the horn wasn't even working (I've been surprised by failed horn a few times). The airspeed idea is good (better than nothing) but doesn't tell the AOA at both wingtips, This probably won't be useful for landing, since the selected airspeed should be high enough to make the AOA at the tips irrelevant. and doesn't seem to account for the G loading in a tight turn. Take another look: both the DSI and the 302 have accelerometers that let them account for G loading. Anyway, the stall/spins typically aren't from tight turns, but shallow ones. Also, as another poster pointed out, the horn detects gusts, which is pretty useful IMHO. I think any gusts that affect your landing will be readily apparent as the glider twitches and bobs in response to them. Certainly they are noted by the pilot while thermalling. Maybe it's time to give airspeed alerts in the pattern a chance. -- ----- change "netto" to "net" to email me directly Eric Greenwell Washington State USA |
#79
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Looks to me that having AOA indicators in the IP for both wingtips to
optimize climbing performance and avoid the onset of spin would be great . Karel, NL "Mark James Boyd" schreef in bericht news:4053a369$1@darkstar... In article , Eric Greenwell wrote: Mark James Boyd wrote: It might be useful to look at small airplane accidents, since they DO have stall warning horns. I'm under the impression that stall/spin accidents are a big cause of fatal accidents also. Do you have any numbers? I looked up the last ten years of gliders (49 fatalities) and then I looked up a three month window of airplane fatalities from 3/94 to 6/94 (102 fatalities). I got lazy and didn't want to look through more than 100, but I wanted to see final reports, so... Gliders: 21 stalls of 49 fatalities = 43% If you eliminate midairs and disconnected controls, 21 of 42 = 50% Airplanes: 9 stalls of 102 fatalities = 9% If you eliminate midairs and disconnected controls, 9 of 91 = 10% A bunch of the airplane ones were also night and/or IFR (less than half). But it seemed real clear that more of the glider fatalities could have been stalls. Anyway, I concluded that airplane guys don't stall very much close to the ground... I was also VERY surprised to find a lot of medical problems with airplenes, and I don't think even one fatal glider accident due to a medical condition. This is really surprising...I'll need to look at all 250 fatal glider reports at some point to see if there are ANY medical fatalities... Anyway, yes glider pilots die from stalls as a real big factor. I think it's because they don't have warning devices. Hells bells, just hook 'em to the gear down and spoiler cracked switches, so they're off the rest of the time (thermalling). Or maybe somebody has a better idea. I dunno, I'm just real surprised we don't have any stall horns at all on any gliders... I'm not suggesting this isn't a good idea, but I do wonder... Why do airplanes have ANY stall/spins during landing? Typically, they have full control of their pattern (altitude, entry point), while the glider accidents most often occur when the pilot can't do the desired pattern because he returns too low. Maybe we don't need a stall warning for gliders: perhaps a simple airspeed alert would do everything that is needed, as long as it was enabled by the gear being extended. I think it should alert regardless of the spoiler position, since a low, slow pilot isn't likely to open the spoilers. DG sailplanes makes such a device, called the DSI. Take a look he http://www.dg-flugzeugbau.de/dsi-e.html DG Flugzeugbau GmbH / DSI - Digital Soaring Indicator Is anyone using one of these? Maybe we already have what we need, but not enough people are using it. Well, some of the power accidents are just newer pilots that weren't trained to properly react to the horn. In some I suspect the horn wasn't even working (I've been surprised by failed horn a few times). The airspeed idea is good (better than nothing) but doesn't tell the AOA at both wingtips, and doesn't seem to account for the G loading in a tight turn. Also, as another poster pointed out, the horn detects gusts, which is pretty useful IMHO. In any case, I'd just love to have a glider with an AOA tab (each with a different tone) on each wingtip, and teach some spins in it. I'd also love to see how well it does when thermalling. Maybe Andreas is right and one can't tell horn vs. vario, but it would be a kick to try... Anyway, just another fun idea...now let's cut out this nonsense and get back to implementing the turbine powered sparrowhawk ;P -- ------------+ Mark Boyd Avenal, California, USA |
#80
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Gear up (soaring): set it a little below normal thermalling speed (about
46 knot setting works on my glider with my 302). Gear down (landing): set it a little below the typical pattern speed (about 50 knots would work on my glider). Some may think this a cheap shot, but what the heck. Believe it or not some pilots fly gliders with fixed gear. They even fly them X-C and make land outs. They even stall/spin them. Too many people in this sport think you need ALL the bells and whistles and a $100,000+ glider to be a "real" glider pilot. That attitude is hurting us. Robert Mudd |
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