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#21
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(...............)
I've routinely stalled our club's Blanik from coordinated turns, and other gliders, too. Establish a shallow banked turn (10-15 degrees, say), then simply slow down while maintaining a coordinated turn. At some point, the inner wing falls and the spin begins. Coordination is important, but not sufficient to protect you from a spin. Correct, coordination and speed will do. If you banked a little more and kept flying coordinated you would at one point reach the aft limit in the Stick travel and not be able to stall / spin... |
#22
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SNIP
I read in one of his notes that Carl Herold doesn't ridge soar any more, because he thinks it is too dangerous. After I read that, I had a little talk with myself about how close I came to ridges a few times... SNIP I cannot recall his exact words, but the interpretation of it that I came away with is-'If you are flying the mountains of the western USA in strong summer conditions there is no reason to get down that low. And if you are that low you are asking for trouble.' IMHO that makes a lot of sense. With 1,000'/minute sink not uncommon in this terrain, working nooks and crannies can bite hard. I have flown with Carl, but cannot recall if we discussed this then. Perhaps someone can refresh my memory, was this thought of his from a forum or post? |
#23
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What is coordinated? Well, if the yaw string or ball were at the CG, and centered, that would be coordinated. Center of pressure or aerodynamic center... but, yeah, right. But the string isn't. It is often in front of and higher than the CG. When this is the case, at high roll rates, and steep banks, keeping the yaw string perfectly centered means I am in a skid. I did some "back of the envelope" caculations, using nothing more than high school trig and geometry and it's not as bad as you think. Assumming a 45 degree banked turn at 55 kts, the turn radius is 240 feet (source American Soaring Handbook). If the yaw string is 6 feet or so in front of the center of pressure, the yaw string error, due to it's position, is 1.4 degrees. Close enough, I think. Tony V. |
#24
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On Wed, 28 Jan 2004 19:25:52 GMT, "Arnold Pieper"
wrote: (...............) I've routinely stalled our club's Blanik from coordinated turns, and other gliders, too. Establish a shallow banked turn (10-15 degrees, say), then simply slow down while maintaining a coordinated turn. At some point, the inner wing falls and the spin begins. Coordination is important, but not sufficient to protect you from a spin. Correct, coordination and speed will do. If you banked a little more and kept flying coordinated you would at one point reach the aft limit in the Stick travel and not be able to stall / spin... Please be very careful about this. Some gliders may not have enough rudder authority under high load factors to achieve stall AOA but some gliders are very happy to snap into a stall over the low wing in the same circumstances. |
#25
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On Wed, 28 Jan 2004 16:32:45 -0500, Todd Pattist
wrote: (Mark James Boyd) wrote: I think a slip is an uncoordinated manuever where both wings are at the same airspeed. A skid is an uncoordinated manuever where the wings are at different airspeeds. A slip can occur while you are flying straight or while turning. By definition, a skid can *only* occur in a turn. Well, maybe so, but my understanding of a skid is a little different. In my notion of a skid it is a flight condition in which the amount of rudder applied is too great for the amount of bank applied. Thus, in my thinking, if you are flying at zero bank - not in a banked turn - ANY application of rudder will result in a skid, not a slip. Please let me know if I have this mixed up! The wings are at different airspeeds in a turn regardless of whether you are slipping, skidding or coordinated. They are at the same airspeed in straight flight regardless of whether you are slipping or coordinated. If you are turning, and the airflow is coming across the fuselage from the outside of the turn, you're in a skid. If it's coming from the inside of the turn, you're in a slip. Straight flight is a coordinated manuever where both wings are at the same airspeed. Banked, turning flight is a coordinated manuever where both wings are at different airspeeds. Todd Pattist - "WH" Ventus C (Remove DONTSPAMME from address to email reply.) |
#26
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What is coordinated? Well, if the yaw string or ball were at the CG, and centered, that would be coordinated. But the string isn't. It is often in front of and higher than the CG. When this is the case, at high roll rates, and steep banks, keeping the yaw string perfectly centered means I am in a skid. Humm, so we are all flying uncoordinated in a turn? I couldn't pass this up, so I calculated how much the yaw string is off. Assume a 300' turn radius, the yaw string is 5' ahead of the CG and is 4" long. With these numbers the yaw string is off by 0.033 inch, much smaller than the diameter of the string itself! Tom |
#27
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Ian, You have near enough admitted that you are extrapolating information that clearly isnt there from the accident reports. In my 15 years of reading S+G I have never seen a 'Competition Pilots not in Competition accident section'. Also accusing every comp pilot of not owning up to incidents is just plain rubbish not to mention insulting. Please keep you amateur accident statistics thoughts to yourself. You dont do anyone any favours including yourself. BTW. I have seen an early solo pilot 'Push on' which resullted in a crash. Was he an aspiring comp pilot, influenced by a comp pilot or did he just get it wrong? Owain At 17:36 28 January 2004, Ian Johnston wrote: On Wed, 28 Jan 2004 12:37:49 UTC, Owain Walters wrote: : we all know, from the accident statistics, just how : safe competition : pilots are, don't we? : : I am assuming you are being sarcastic? Yup. : Where are you : getting your competition vs. normal flying accident : statistics from? Reading the blood-and-gore pages of S&G : I am interested because the vast majority of accident : reports I read are nothing to do with competitions. Well of course not. When you stuff up landing a glider in a field after pressing on, too late, too low and too tired, you don't have to compound things by owning up ... Incidentally, note that I said 'competition pilots' and not 'pilots flying in competitions' ... Ian |
#28
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On Wed, 28 Jan 2004 19:25:52 GMT, "Arnold Pieper"
wrote: (...............) I've routinely stalled our club's Blanik from coordinated turns, and other gliders, too. Establish a shallow banked turn (10-15 degrees, say), then simply slow down while maintaining a coordinated turn. At some point, the inner wing falls and the spin begins. Coordination is important, but not sufficient to protect you from a spin. Correct, coordination and speed will do. If you banked a little more and kept flying coordinated you would at one point reach the aft limit in the Stick travel and not be able to stall / spin... Please be very cautious about this. Some gliders may have insufficient elevator authority to reach stall AOA under higher load factors but this is not true of all gliders. Some do have the elevator authority to very happily stall and fall off over the low wing under higher load factors. The location of the Center of Gravity in a particular flight influences this, but we still must be prepared for stalls out of steep turns. |
#29
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If you have zero bank, and apply rudder you will begin
a flat turn. Wrong! UTTERLY WRONG!!!! A rudder yaws the airframe, it does not 'turn' or 'steer' the aircraft. Your whole problem seems to be in compairing a glider with a boat. They may both have rudders, but they both do totally different things. Next time you fly in your glider, line yourself up with a straight feature. Apply some rudder to yaw the glider, but keep the wings level. All you will do is continue in a straight line, sideways on. (commonly known as a side slip) However, the rudder does has a secondary control effect, which introduces a roll moment due to differences in lift between the wings. (which is why the first thing you do is apply full opposite rudder to counteract the rotation in a spin) It is the ailerons that instigate a turn, the rudder is used in a coordinated manner to 1) check the adverse yaw (secondary effect of ailerons), and 2) to align the airframe correctly into the airflow. Please stop using language which inforces a belief that the rudder is used to turn a glider in flight. Your very action in doing so may well end up enforcing that belief into a low airtime pilot reading these posts and KILLING THEM! |
#30
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