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#41
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Thomas Borchert opined
Ash, Perhaps the FAA could be useful and do some research. IMHO, that research would be totally useless. From common experience with the planes we all fly, what effect do you expect? Zilch, nada, niente. So why bother to do research? Because for a sort period of time, the FAA will not be doing something else which will make life worse for us. -ash Cthulhu for President! Why vote for a lesser evil? |
#42
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"C J Campbell" wrote in message
... I really love flying this plane. It handles nicely and takes bumps more gracefully then high wing planes. In what way do you mean takes bumps more gracefully? Is there some way to quantify this? The way a plane handles bumps is a function of wing loading instead of where the wing is located. Seems to me one either needs to define "handles bumps" more specifically, or one needs to accept that wing position does affect how an airplane "handles bumps" as well as wing loading. Just as putting the CG fore or aft of the main gear affects an airplane moving forward on the ground, I would expect putting the CG above or below the wing would affect the airplane moving about in the air. For example, ignoring the horizontal stabilizer for a moment, if an airplane pitches up or down in response to a gust, it will have negative stability with the CG above the wing, and positive stability with the CG below the wing. Of course, a properly designed horizontal stabilizer cures many ills, and this effect may or may not be perceptible in actual airplanes. But surely one can't say that there's no effect due to wing placement. As a corallary, I find it puzzling that someone would claim low-wing airplanes are superior to high-wing airplanes with respect to "bumps", since the only theoretical difference I can think of implies that high wings would be better. Pete |
#43
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#44
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"C J Campbell" wrote
We have one second-hand report of an instructor like this. No, we have the latest report of an instructor like this. Over the years, I've noticed that they pop up with great regularity. In fact, I remember contributing one myself a bit over a decade ago. Every other instructor who posts here disagreed with him. Thank heaven for small favors. But the instructors here are hardly representative of the instructor population as a whole. Yet you think this single instructor represents the "rule" rather than the "exception." My experience indicates to me that this is indeed the case. Using some highly sophisticated tools (lawnchair and cold beverage) I have been able to observe the speeds flown on final many times, and at many airports. The vast majority are flying final too fast. Michael |
#45
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Someone correct me if I'm wrong, but changes in engine performance
wouldn't affect Vx or Vy would they? It might affect the power settings necessary for these speeds, or the plane effectiveness in holding them, but my understanding is that Vx and Vy are determined by the aerodynamics of the design of the plane and it's weight. Changes in an engines performance with age shouldn't affect these speeds, should they? Snowbird wrote: "Peter Duniho" wrote in message ... "Snowbird" wrote in message .com... 'Scuse, Peter, but I said "all the V speeds you're talking about", not "all V-speeds". As best I can tell, the original poster was talking about Vr, and landing speed. Whatever. I find Vx and Vy to be perfectly relevant in this thread, even looking at only the first post. You want to be offended, go right ahead...wouldn't be the first time. Vx and Vy are certainly relevant to bring into the discussion, but they weren't mentioned in the original poster's description, and I referred to that. You were responding to my post, and saying "not true" to me. I simply clarified what I'd meant. That doesn't mean that Vx and Vy aren't relevant to introduce, as additional factors which *are* dependent on factors other than stall speed. It's a reasonable point -- provided it's not introduced in a way which puts words into someone else's mouth or refutes a claim they weren't making. I await your explanation of Vr and what it depends upon, and I note that one can fly behind an engine later shown to have one cylinder completely flat, and not notice any particular changes to Vy, the rate of climb obtained at that speed (under DA conditions not near the edge of the envelope, admittedly), or cruise airspeed. Cheers, Sydney |
#46
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"Matt Young" wrote in message
news ![]() Someone correct me if I'm wrong, but changes in engine performance wouldn't affect Vx or Vy would they? As I mentioned before, Vx and Vy are functions of excess thrust and power, respectively. In particular, they are the airspeeds at which excess thrust and power are at their maximum. If thrust were constant, Vx would happen at minimum drag airspeed regardless of engine power. But thrust isn't constant; it varies with airspeed, and the airspeed at which the thrust in excess of drag is at its maximum depends on how much engine power you have. For the same reason that thrust isn't constant (propeller efficiency changes with airspeed), power isn't constant either, and again, the airspeed at which the power in excess of power required for level flight is at its maximum depends on how much engine power you have. You can demonstrate for yourself that Vx and Vy depend on engine power, by considering the difference between relevant airspeeds when there's no engine power. Best glide airspeed isn't the same as Vx, even though both airspeeds provide the best performance of the aircraft in terms of altitude change over distance. Likewise, minimum sink airspeed isn't the same as Vy, even though both airspeeds provide the best performance of the aircraft in terms of altitude change over time. Generally speaking, the differences between all of these airspeeds isn't huge, but it's important to understand that they aren't the same. [...] Changes in an engines performance with age shouldn't affect these speeds, should they? Not significantly enough for the published speeds to be unusable. If the engine performance has changed enough to affect Vx and Vy significantly, there's something wrong with the engine. But it's false to say that they aren't affected at all. Pete |
#47
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![]() "Michael" wrote: What you say is true, but only because what you refer to as a completely flat cylinder is not in any way equivalent to a cylinder not making power. A completely flat cylinder is what a mechanic will call a cylinder that is not anywhere close to making compression in a static test - meaning it only makes, say, 20/80 or even less. I have in fact had this happen - ...There was no noticeable impact on performance, Yep, I've even had this happen on *two* cylinders on the same side of a LYC O-360 and noticed nothing until a just-for-the-hell-of-it compression test revealed the bad news. The engine was running nice and smooth. -- Dan C172RG at BFM |
#48
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![]() "Michael" wrote in message om... My experience indicates to me that this is indeed the case. Using some highly sophisticated tools (lawnchair and cold beverage) I have been able to observe the speeds flown on final many times, and at many airports. The vast majority are flying final too fast. Well, OK. But I want to see how you measure the speed of airplanes using a lawnchair and cold beverage. :-) |
#49
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On Fri, 2 Jul 2004 19:19:53 -0700, "C J Campbell"
wrote: "Michael" wrote in message . com... My experience indicates to me that this is indeed the case. Using some highly sophisticated tools (lawnchair and cold beverage) I have been able to observe the speeds flown on final many times, and at many airports. The vast majority are flying final too fast. Well, OK. But I want to see how you measure the speed of airplanes using a lawnchair and cold beverage. :-) That's no problem. The more cold beverages the faster the approaches. The lawn chair provides a stable platform to conduct the test. z |
#50
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"zatatime" wrote in message
... That's no problem. The more cold beverages the faster the approaches. I think you have that backwards. The more cold beverages you can consume during an approach, the *slower* it was. Maybe you had too many cold beverages? ![]() |
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