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#21
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Doug overstates the case a bit. Even without elevator
control it is possible to damp out the phugoid mode. I tried this on a BFR recently and I encourage the rest of you to give it a try as well. Since the phugoid is a function of airspeed/pitching moment coupling, you can damp it out by applying speedbrakes at the bottom of the cycle. This take a bit of thinking ahead, but it can be managed with practice. The United 232 crew was able to control pitch through pitch/thrust coupling. They applied collective thrust to adjust pitch and differential thrust for directional control. It was crude put effective enough to get to the runway threshold. Unfortunately, the dug s wing in on landing. It was not directly a result of the phugoid mode, though I suspect all the different modes conspired a bit. At 00:48 01 November 2003, Doug Haluza wrote: (nowhere) wrote in message news:... Yes, according to Peter Garrison's 'Aftermath' column in the November issue of 'Flying' you don't need to connect your elevator control! I quote: 'the NTSB report does not comment on the fact that a disconnected elevator does not make an ASW-20, or for that matter any other airplane, unflyable. The situation is aerodynamically no different from what occurs when the pilot removes his hand from the stick.' I think I'll start leaving the elevators off my ASW-15 now. Imagine how the reduction in drag will improve the performance! Not having to worry about pitch control will certainly cut down on the cockpit workload as well. The benefits are endless! Well, it may be flyable, but not landable! The stick free phugoid can get pretty dramatic, even with the mass and friction of the stick attached to provide some damping . If you have not tried this, you should. Keep hands completely off and keep the wings level with rudder. Let the phugoid fully develop--it's a real roller coaster ride. Close to the ground, it's a crap shoot whether you would land or crash. There was an accident a few years back in a DG-800 that had a loose nut on the elevator control. The pilot hit on the down part of the phugoid and crashed wings level. He lived, but never flew again. The same thing happened to United Flight 232, the DC-10-10, that crashed while attempting an emergency landing at the Sioux City Gateway Airport, Iowa, in 1989. After losing all hydraulics, they had no movable flight controls. They were able to fly the aircraft with differential thrust on the two wing engines, but they could not control pitch on final approach. I have not seen the article, but I'm surprised that a knowledgable person would suggest that elevator control is optional. |
#22
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On 1 Nov 2003 04:25:38 GMT, Andy Blackburn
wrote: The United 232 crew was able to control pitch through pitch/thrust coupling. They applied collective thrust to adjust pitch and differential thrust for directional control. It was crude put effective enough to get to the runway threshold. Unfortunately, the dug s wing in on landing. It was not directly a result of the phugoid mode, though I suspect all the different modes conspired a bit. One might mention that NASA tried to recreate this 232'2 landing using a simulator (as well as an F-15). No aircrew *ever* was able to touch down their aircraft soft enough to make the crash survivable. Bye Andreas |
#23
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I think it would be difficult to overstate the severity of a total
loss of elevator control. It is possible to damp out the phugoid with spoiler (and/or flap) but this won't help much close to the ground. Deploying spoiler on the down part of the phugoid will reduce your forward speed, but it will increase your vertical speed. The rate of descent at impact is the real problem. It may be theoretically possible to do something that could later be classified as a landing, rather than a crash. But you only have one chance to do this, and the probability of doing it exactly right on your first try is not very high. United 232 did not dig in a wing and cartwheel. The aircraft hit the ground with a high descent rate (1850 fpm) slightly right wing low. The right main gear broke through 12" of concrete, and the wing broke off along with the tail section on impact. The rate of descent, and loss of the wing, was a direct result of the phugoid mode. P.S. For a very interesting first hand account of Flight 232 from Capt Haynes see: http://www.panix.com/~jac/aviation/haynes.html Andy Blackburn wrote in message ... Doug overstates the case a bit. Even without elevator control it is possible to damp out the phugoid mode. I tried this on a BFR recently and I encourage the rest of you to give it a try as well. Since the phugoid is a function of airspeed/pitching moment coupling, you can damp it out by applying speedbrakes at the bottom of the cycle. This take a bit of thinking ahead, but it can be managed with practice. The United 232 crew was able to control pitch through pitch/thrust coupling. They applied collective thrust to adjust pitch and differential thrust for directional control. It was crude put effective enough to get to the runway threshold. Unfortunately, the dug s wing in on landing. It was not directly a result of the phugoid mode, though I suspect all the different modes conspired a bit. At 00:48 01 November 2003, Doug Haluza wrote: (nowhere) wrote in message news:... Yes, according to Peter Garrison's 'Aftermath' column in the November issue of 'Flying' you don't need to connect your elevator control! I quote: 'the NTSB report does not comment on the fact that a disconnected elevator does not make an ASW-20, or for that matter any other airplane, unflyable. The situation is aerodynamically no different from what occurs when the pilot removes his hand from the stick.' I think I'll start leaving the elevators off my ASW-15 now. Imagine how the reduction in drag will improve the performance! Not having to worry about pitch control will certainly cut down on the cockpit workload as well. The benefits are endless! Well, it may be flyable, but not landable! The stick free phugoid can get pretty dramatic, even with the mass and friction of the stick attached to provide some damping . If you have not tried this, you should. Keep hands completely off and keep the wings level with rudder. Let the phugoid fully develop--it's a real roller coaster ride. Close to the ground, it's a crap shoot whether you would land or crash. There was an accident a few years back in a DG-800 that had a loose nut on the elevator control. The pilot hit on the down part of the phugoid and crashed wings level. He lived, but never flew again. The same thing happened to United Flight 232, the DC-10-10, that crashed while attempting an emergency landing at the Sioux City Gateway Airport, Iowa, in 1989. After losing all hydraulics, they had no movable flight controls. They were able to fly the aircraft with differential thrust on the two wing engines, but they could not control pitch on final approach. I have not seen the article, but I'm surprised that a knowledgable person would suggest that elevator control is optional. |
#24
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I would not suggest that loss of elevator is anything
but the most serious of mechanical incidents. However, if it should ever happen, instead of throwing your hands into the air and resigning yourself to a certain fate, there are controls that you might be able to use to maintain some measure of control - namely speedbrakes and flaps (if you have 'em). Will it be a pretty landing? Unlikely. Nevertheless, it beats the alternative. I recommend practicing this rather than trying to figure it out in real time in an emergency. I have practiced flying without the use of each of the controls for this reason. Doug's right on UA 232 - the gear hit before the right wing. The earlier comment was that the crew were unable to control pitch with thrust. More precisely, they were not able to adequately control pitch or heading to make a good landing. If they had totally lost pitch authority there would have been no survivors - which I think was the main point. Use whatever control you have. 9B At 17:12 01 November 2003, Doug Haluza wrote: I think it would be difficult to overstate the severity of a total loss of elevator control. It is possible to damp out the phugoid with spoiler (and/or flap) but this won't help much close to the ground. Deploying spoiler on the down part of the phugoid will reduce your forward speed, but it will increase your vertical speed. The rate of descent at impact is the real problem. It may be theoretically possible to do something that could later be classified as a landing, rather than a crash. But you only have one chance to do this, and the probability of doing it exactly right on your first try is not very high. United 232 did not dig in a wing and cartwheel. The aircraft hit the ground with a high descent rate (1850 fpm) slightly right wing low. The right main gear broke through 12' of concrete, and the wing broke off along with the tail section on impact. The rate of descent, and loss of the wing, was a direct result of the phugoid mode. P.S. For a very interesting first hand account of Flight 232 from Capt Haynes see: http://www.panix.com/~jac/aviation/haynes.html Andy Blackburn wrote in message news:... Doug overstates the case a bit. Even without elevator control it is possible to damp out the phugoid mode. I tried this on a BFR recently and I encourage the rest of you to give it a try as well. Since the phugoid is a function of airspeed/pitching moment coupling, you can damp it out by applying speedbrakes at the bottom of the cycle. This take a bit of thinking ahead, but it can be managed with practice. The United 232 crew was able to control pitch through pitch/thrust coupling. They applied collective thrust to adjust pitch and differential thrust for directional control. It was crude put effective enough to get to the runway threshold. Unfortunately, the dug s wing in on landing. It was not directly a result of the phugoid mode, though I suspect all the different modes conspired a bit. At 00:48 01 November 2003, Doug Haluza wrote: (nowhere) wrote in message news:... Yes, according to Peter Garrison's 'Aftermath' column in the November issue of 'Flying' you don't need to connect your elevator control! I quote: 'the NTSB report does not comment on the fact that a disconnected elevator does not make an ASW-20, or for that matter any other airplane, unflyable. The situation is aerodynamically no different from what occurs when the pilot removes his hand from the stick.' I think I'll start leaving the elevators off my ASW-15 now. Imagine how the reduction in drag will improve the performance! Not having to worry about pitch control will certainly cut down on the cockpit workload as well. The benefits are endless! Well, it may be flyable, but not landable! The stick free phugoid can get pretty dramatic, even with the mass and friction of the stick attached to provide some damping . If you have not tried this, you should. Keep hands completely off and keep the wings level with rudder. Let the phugoid fully develop--it's a real roller coaster ride. Close to the ground, it's a crap shoot whether you would land or crash. There was an accident a few years back in a DG-800 that had a loose nut on the elevator control. The pilot hit on the down part of the phugoid and crashed wings level. He lived, but never flew again. The same thing happened to United Flight 232, the DC-10-10, that crashed while attempting an emergency landing at the Sioux City Gateway Airport, Iowa, in 1989. After losing all hydraulics, they had no movable flight controls. They were able to fly the aircraft with differential thrust on the two wing engines, but they could not control pitch on final approach. I have not seen the article, but I'm surprised that a knowledgable person would suggest that elevator control is optional. |
#25
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Agreed. The problem with thinking through the possibilities for
control is that the pilot's assembly error will put the tow pilot at risk immediately. Do you have a right to relearn how to fly your semi-controllable aircraft by putting his or her life in danger? I've seen several no elevator launches, and in each case, the pilot discovered his error when he pitched high behind the towplane. This is a good mental exercise, thinking about how other control surfaces can be used to manage the aircraft, but I wonder just how ethical it is to try to apply them at the cost of someone else's life. I don't have an answer for this one. Just thought I'd throw another variable into the discussion. |
#26
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An article appeared in Soaring Magazine a few years ago titled "Attitude
Problems" dealing with ways of dealing with an unconnected elevator control. Pilots of flapped ships can use flaps, spoilers and bank angle to adjust pitch, standard ships the last two. Gliders using a tow release in the nose will be more easily controlled on air tow than those using a cg release, but, if an initial zoom up after take off can be controlled, the latter can be controlled sufficiently to allow a high tow and possible bailout as well. As pointed out in an earlier contribution to this discussion, trying to simulate a disconnected elevator by allowing the stick to move freely in pitch won't create the same degree of instability, but it is still a useful exercise. Varying the bank angle to arrest phugoid zoomies is very easy to accomplish (steepen bank to lower nose and vice versa). When a bailout is not an option, use of this mode alone will result in the glider coming to back to earth tangentially at a reasonable speed. Anyone interested in a copy of the mentioned article can contact me. Karl Striedieck "Andy Blackburn" wrote in message ... I would not suggest that loss of elevator is anything but the most serious of mechanical incidents. However, if it should ever happen, instead of throwing your hands into the air and resigning yourself to a certain fate, there are controls that you might be able to use to maintain some measure of control - namely speedbrakes and flaps (if you have 'em). Will it be a pretty landing? Unlikely. Nevertheless, it beats the alternative. I recommend practicing this rather than trying to figure it out in real time in an emergency. I have practiced flying without the use of each of the controls for this reason. Doug's right on UA 232 - the gear hit before the right wing. The earlier comment was that the crew were unable to control pitch with thrust. More precisely, they were not able to adequately control pitch or heading to make a good landing. If they had totally lost pitch authority there would have been no survivors - which I think was the main point. Use whatever control you have. 9B At 17:12 01 November 2003, Doug Haluza wrote: I think it would be difficult to overstate the severity of a total loss of elevator control. It is possible to damp out the phugoid with spoiler (and/or flap) but this won't help much close to the ground. Deploying spoiler on the down part of the phugoid will reduce your forward speed, but it will increase your vertical speed. The rate of descent at impact is the real problem. It may be theoretically possible to do something that could later be classified as a landing, rather than a crash. But you only have one chance to do this, and the probability of doing it exactly right on your first try is not very high. United 232 did not dig in a wing and cartwheel. The aircraft hit the ground with a high descent rate (1850 fpm) slightly right wing low. The right main gear broke through 12' of concrete, and the wing broke off along with the tail section on impact. The rate of descent, and loss of the wing, was a direct result of the phugoid mode. P.S. For a very interesting first hand account of Flight 232 from Capt Haynes see: http://www.panix.com/~jac/aviation/haynes.html Andy Blackburn wrote in message news:... Doug overstates the case a bit. Even without elevator control it is possible to damp out the phugoid mode. I tried this on a BFR recently and I encourage the rest of you to give it a try as well. Since the phugoid is a function of airspeed/pitching moment coupling, you can damp it out by applying speedbrakes at the bottom of the cycle. This take a bit of thinking ahead, but it can be managed with practice. The United 232 crew was able to control pitch through pitch/thrust coupling. They applied collective thrust to adjust pitch and differential thrust for directional control. It was crude put effective enough to get to the runway threshold. Unfortunately, the dug s wing in on landing. It was not directly a result of the phugoid mode, though I suspect all the different modes conspired a bit. At 00:48 01 November 2003, Doug Haluza wrote: (nowhere) wrote in message news:... Yes, according to Peter Garrison's 'Aftermath' column in the November issue of 'Flying' you don't need to connect your elevator control! I quote: 'the NTSB report does not comment on the fact that a disconnected elevator does not make an ASW-20, or for that matter any other airplane, unflyable. The situation is aerodynamically no different from what occurs when the pilot removes his hand from the stick.' I think I'll start leaving the elevators off my ASW-15 now. Imagine how the reduction in drag will improve the performance! Not having to worry about pitch control will certainly cut down on the cockpit workload as well. The benefits are endless! Well, it may be flyable, but not landable! The stick free phugoid can get pretty dramatic, even with the mass and friction of the stick attached to provide some damping . If you have not tried this, you should. Keep hands completely off and keep the wings level with rudder. Let the phugoid fully develop--it's a real roller coaster ride. Close to the ground, it's a crap shoot whether you would land or crash. There was an accident a few years back in a DG-800 that had a loose nut on the elevator control. The pilot hit on the down part of the phugoid and crashed wings level. He lived, but never flew again. The same thing happened to United Flight 232, the DC-10-10, that crashed while attempting an emergency landing at the Sioux City Gateway Airport, Iowa, in 1989. After losing all hydraulics, they had no movable flight controls. They were able to fly the aircraft with differential thrust on the two wing engines, but they could not control pitch on final approach. I have not seen the article, but I'm surprised that a knowledgable person would suggest that elevator control is optional. |
#27
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"JJ Sinclair" wrote in message ... I know of a Kestrel 19 that's done the same, twice. The wing attach design is very much the same. The pin is not load bearing, but only locks the wings together. As long a 0 to negative G is avoided, they won't come off. Come on guys, this story is getting out of hand. Your asking us to believe that a Kestrel driver used his neat little wing assembly tool to force his wings together and then FORGOT to put the main pin in? And you say he did it twice? That pin is not load bearing, but any turbulance (like what we do to make the wing come out, on didassembly) will allow the wings to slide out and then our fictitious Kestrel driver would find himself wingless. JJ Sinclair Nevertheless, the owner admitted to doing this twice. Frank |
#28
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"F.L. Whiteley" wrote in message ... "JJ Sinclair" wrote in message ... I know of a Kestrel 19 that's done the same, twice. The wing attach design is very much the same. The pin is not load bearing, but only locks the wings together. As long a 0 to negative G is avoided, they won't come off. Come on guys, this story is getting out of hand. Your asking us to believe that a Kestrel driver used his neat little wing assembly tool to force his wings together and then FORGOT to put the main pin in? And you say he did it twice? That pin is not load bearing, but any turbulance (like what we do to make the wing come out, on didassembly) will allow the wings to slide out and then our fictitious Kestrel driver would find himself wingless. JJ Sinclair Nevertheless, the owner admitted to doing this twice. Frank Maybe the tape and control linkages are _just_ enough........ One of our club members also landed his Std Jantar 2 following a winch launch. A young lady that walked out to look at the glider picked up the horizontal tail attach pin and handed it to him, as it had fallen out on landing. He painted it in such a way that if it wasn't properly seated, a color would show. He then booked a flight to Majorca to 'enjoy life' and the fact that he was still living it. Frank |
#29
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"F.L. Whiteley" wrote in message ... | Maybe the tape and control linkages are _just_ enough........ The control linkages on the Glasfluegel ships are automatic, so won't hold anything in. The tape may have been his salvation... Cheers, John G. |
#30
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One of our club members also landed his Std Jantar 2 following a winch
launch. A young lady that walked out to look at the glider picked up the horizontal tail attach pin and handed it to him, as it had fallen out on landing. Where I used to fly, we had a pilot landing his Jantar when I saw the elevator lift off the vertical tail plane by about a foot and start rotating. The glider pitched up and banked, a wing dug in the ground and I think I saw that wing bend about 45 degrees. I took off running as the glider was heading for me. I had learned to keep an eye out when this pilot landed as twice before I had to run to avoid ground loops (no offense to the pilot is meant, he is a good pilot who flies every weekend). After the glider came to a rest I ran up to him and he was sitting in the glider with a stunned look on his face and the cockpit was half filled with dirt, the tops of the pilots knees where sticking up out of the dirt. Craig |
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