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#91
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In article ,
Chris OCallaghan wrote: I don't have the time right now, but anyone care to hazard a few lines of discussion on the increase in induced drag during a slip and compare it with the high speed, high drag descent Cindy described? It might start something like this: During a slip, the effective span and aspect ratio of the wing and elevator decrease substantially. Additionally, total lift required to maintain a constant airspeed is much increased (without any increase in g loading) due to the tilting of the lift vector. Therefore, a much higher angle of attack is required to maintain a given (low) airspeed, one which might be employed to accomplish a steep approach into a very short field. Different circumstances, of course. But it would be interesting to see someone develop this. Frankly, I don't think I've ever seen an analysis of a slip that properly weighs the effects of induced drag. Just out of interest, Cindy, according your data, which creates the steepest approach (min L/D) (as opposed to greatest sink rate)? Yes, we're likely to get some discussion on TV airbrakes, but we'll just have to suffer through that. Well, the 2-33 manual says in a full slip that something like 45 to 50mph gives the most efficient slip. I wonder if this means most amount of altitude loss for distance travelled, or highest sink rate per minute. I'd believe the first, but have trouble believing the second. And if it really is just best altitude loss for distance of glide, then wind effects could change the correct speed significantly... |
#92
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Well, not only have you missed my point but you have confused me with
someone else. To what theories of flight dynamics are you referring? I don't have any theories on flight dynamics. It also seems that your "group" is starved for items of amusement. My theory on spinning is simple - don't get into one and you won't have to recover! My point, to which you took exception, had to do with the thought that power pilots are deemed to be inferior to ab initio glider pilots when learning to fly gliders and that power training is of little use when transitioning to gliders. Having run into this perception multiple times, I pointed out that it is nonsense. The few differences that define glider flying are small when compared to the differences between powered aircraft. Aerodynamics are aerodynamics. They apply to gliders, powered aircraft, buzz bombs and flat plates. You just have to be aware of the differences. Allan "Pete Zeugma" wrote in message ... At 10:00 04 February 2004, Adp wrote: It appears that you have missed my point - but managed to illustrate it very nicely! I rest my case. Allan Hardly, been busy and away from the office. Plus pilotnet has been down the last couple days. This just fills in my time between while waiting for software builds to complie. Mind you, your theories on flight dynamics have caused intence amusement here. several posts are currently on our main notice board collecting comments from within the flight dynamics group! |
#93
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Pete,
It sounds like you have the axioms down pat, but are having a little trouble with recognizing that the controls allow pilots to do all sorts of things that the designer didn't intend. Of course you can (not should) rudder a glider wings level around a turn. Just like the rudder on a boat. This is commonly called a skid. Frankly, I can't tell whether you are trolling or exhibiting genuine ignorance. Let's hope it is the latter -- there's a cure for what you don't know. At any rate, I'd stop arguing on this point until you've had a discussion with a CFI, power or sailplane. Your heart appears to be in the right place. (It's the wings that turn an aiplane. The rudder is to counteract adverse yaw.) But you're failing to recognize how a pilot can abuse the controls to a variety of ends. Slips are one. Skidding turns another. Stalls still another. Some are useful. Some less so. Skidding turns fall into the second category. |
#94
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"Bill Daniels" wrote in message ...
Cindy, perhaps you would address that bit of nonsense in the Private Pilot Practical Test Standards about no-spoiler accuracy landings. (I've always thought it was there in order to make the PTS 2-33 specific.) Bill Daniels When I was more active instructing I used to give students simulated airbrakes jammed full open and jammed closed (separate flights). I expected them to demonstrate that they could complete the circuit and landing. I released the malfunction on short final, or sooner if they couldn't cope. Isn't the PTS requirement to demonstate simulated jammed closed? Andy |
#95
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"Bill Daniels" wrote in message ...
Cindy, perhaps you would address that bit of nonsense in the Private Pilot Practical Test Standards about no-spoiler accuracy landings. (I've always thought it was there in order to make the PTS 2-33 specific.) Bill Daniels That would have to be "Schweizer specific" at the very least wouldn't it, Bill? I was once forced by reason of a 2-32's spoilers being frozen solidly closed to slip from 28,000 ft MSL near Pikes Peak to land without them at old BFGP. (Not much of an accuracy landing challenge there, of course, but my feet were pretty cold and I was grateful for the rate of descent). FAA's aircraft registry lists at least 1335 Schweizers having spoilers or divebrakes of similar configuration, of which 2-33's of all varieties number only 375. I'm embarassed to admit that I've also inadvertently jettisoned the drag chute on a Salto on the base leg to a much smaller landing site where I really could have used it, and an agressive slipping turn to final made the difference between an otherwise certain overshoot and a merely memorable pattern. Modern sailplanes don't ordinarily present as much flat plate to the airstream and plummet from altitude quite as dramatically as the Schweizers, but they all descend a bit more steeply flying sideways and there are any number of reasons that extra little increment of drag may be useful. As training exercise, I'd argue that no-spoiler slipping patterns to an accuracy landing can be uses to develop advanced levels of both judgement and command of the aircraft in maneuvering with attention focused largely outside the cockpit. In that sense, is demonstrating proficiency in it any less "practical" a test item than some of the ground reference maneuvers found in the airplane PTS? |
#96
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"Eric Coleson" wrote in message om... "Bill Daniels" wrote in message ... Cindy, perhaps you would address that bit of nonsense in the Private Pilot Practical Test Standards about no-spoiler accuracy landings. (I've always thought it was there in order to make the PTS 2-33 specific.) Bill Daniels That would have to be "Schweizer specific" at the very least wouldn't it, Bill? I was once forced by reason of a 2-32's spoilers being frozen solidly closed to slip from 28,000 ft MSL near Pikes Peak to land without them at old BFGP. (Not much of an accuracy landing challenge there, of course, but my feet were pretty cold and I was grateful for the rate of descent). FAA's aircraft registry lists at least 1335 Schweizers having spoilers or divebrakes of similar configuration, of which 2-33's of all varieties number only 375. I'm embarassed to admit that I've also inadvertently jettisoned the drag chute on a Salto on the base leg to a much smaller landing site where I really could have used it, and an agressive slipping turn to final made the difference between an otherwise certain overshoot and a merely memorable pattern. Modern sailplanes don't ordinarily present as much flat plate to the airstream and plummet from altitude quite as dramatically as the Schweizers, but they all descend a bit more steeply flying sideways and there are any number of reasons that extra little increment of drag may be useful. As training exercise, I'd argue that no-spoiler slipping patterns to an accuracy landing can be uses to develop advanced levels of both judgement and command of the aircraft in maneuvering with attention focused largely outside the cockpit. In that sense, is demonstrating proficiency in it any less "practical" a test item than some of the ground reference maneuvers found in the airplane PTS? I've watched pilot attempt a no-spoiler approach in a Grob 103 and the only way that a reasonably accurate landing could be done was to fly way too slow for comfort because the 103 floats so far in ground effect. My Nimbus 2C (No tail 'chute) floats so far that if the air brakes don't work, I'll need several kilometers of runway to get stopped. If you have a glider that exhibits a pronounced float in ground effect, I'd advise against a no-spoiler approaches. I think this may be where accidents due to training will be greater than those due to a real spoiler failure. Bill Daniels |
#97
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At 18:30 04 February 2004, Adp wrote:
My theory on spinning is simple - don't get into one and you won't have to recover! strangly, thats basically what ive been saying all along, and objecting to the 'experts' who insist its ok to turn a glider using rudder alone! My point, to which you took exception, had to do with the thought that power pilots are deemed to be inferior to ab initio glider pilots when learning to fly gliders didnt mention ab initio at all, neither did i say they were inferior. and that power training is of little use when transitioning to gliders. actually i said that there was a degree of unlearning and bad habits that typically show up, in this particularly instance the general theme was in the misuse of the rudder pedals and the misguided belief that because you can do something in a powered aircraft the same must apply to gliders. Having run into this perception multiple times, I pointed out that it is nonsense. you may well think so in your own experiences, however it still remains true. old habits are hard to break, especially when they become instinctive. The few differences that define glider flying are small when compared to the differences between powered aircraft. and it is those small differences which when wrongly applied to glider flight can rapidly end life! Aerodynamics are aerodynamics. They apply to gliders, powered aircraft, buzz bombs and flat plates. You just have to be aware of the differences. no argument there. |
#98
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"Bill Daniels" wrote in message
If you have a glider that exhibits a pronounced float in ground effect, I'd advise against a no-spoiler approaches. I think this may be where accidents due to training will be greater than those due to a real spoiler failure. Bill Daniels I think the distinction should be made between no spoiler patterns/circuit/approaches and no spoiler landings. I think a simulated jammed closed, or jammed open, situation is useful training but, as I said earlier, I always released the malfunction on short final. The landing float was not an issue as spoiler/airbrake could be used for the landing. When doing simulated engine fails with airplane pilots I always make it clear that the engine is available on short final. No point in busting the airplane with a hard landing. Andy |
#99
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Pete Zeugma wrote in message ...
strangly, thats basically what ive been saying all along, and objecting to the 'experts' who insist its ok to turn a glider using rudder alone! Pete, No one in this group has suggested it is "OK to turn a glider using rudder alone." In an earlier post you stated in no uncertain terms that turning a glider with rudder only was an aerodynamic impossiblity. You then "proved" your point by stating that unbalanced movement of the rudder produces a forward slip. Is it surprising that several of the group's readers, ones who lay hands on the controls occasionally, took exception? Your absolutism isn't uncommon. It is a tool used by good students to learn and apply their lessons. It is especially common in flight training, where instuctors must daily grapple with the fact that they are giving their students access to an environment that capitalizes on any lack of experience and exacts a brutal cost when it finds pilots wanting. An axiomatic approach is warranted -- a short cut, proven to be a fair trade between rapid progress to certification and safety in the air. A pilot can even afford to arrest his development at this point, but if you are going to engage in discussions on the philosophy of flight, you'll need to start looking behind the short cuts your flight instructor proffered to keep you safe in the air. I assume your need for a strawman is a first step in overcoming denial. That's a good thing. Get past this. |
#100
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At 13:42 05 February 2004, Chris Ocallaghan wrote:
Your absolutism isn't uncommon. It is a tool used by good students to learn and apply their lessons. its also an approach used as an instructor, for good reasons. It is especially common in flight training, where instuctors must daily grapple with the fact that they are giving their students access to an environment that capitalizes on any lack of experience and exacts a brutal cost when it finds pilots wanting. quite right. so does it not make you rather disturbed when you read posts the suggest that its you can turn a glider with rudder alone? what brutal cost will that exact on the poor sod who reads some of todds posts and puts it into practice when flying low and slow, 'oh, todd said i can make a flat turn using my rudder' An axiomatic approach is warranted -- a short cut, proven to be a fair trade between rapid progress to certification and safety in the air. actually, there is no warrented approach or short cut between progress and safety in the air. basic understanding of the correct use of controls and why it is so important to engrain into a student the necessity to fly coordinated in turns at all times. A pilot can even afford to arrest his development at this point, but if you are going to engage in discussions on the philosophy of flight, you'll need to start looking behind the short cuts your flight instructor proffered to keep you safe in the air. my instructor, some 28 years ago now, taught me well. he drilled into me why you fly turns correctly, why you dont over rudder in turns. the gliders flown way back then had a habit of killing those who did not. i dont know of any instructor who looks for short cuts. go read the BGA instructors manual. it explains quite nicely why right from the first moment it should be drummed into a trainees head 'that the rudder does not turn a glider like a boat' and if you disagree, email the BGA and give them your little gems of wisdom. I assume your need for a strawman is a first step in overcoming denial. That's a good thing. Get past this. if being in denial is to confront and challenge techniques used by power pilots being encouraged or suggested to be used with gliders then so be it. If challenging claims that a glider will turn wings level just with the rudder alone, due to the fuselage generating lift, then so be it. or do you not think you have a duty of responsibility to prevent accidents and death..... if you have not noticed, there is already one low-time pilot who has picked up on some of the ideas stated here, and is thinking of trying them out.......... |
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