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#21
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On Sun, 22 Feb 2004 12:19:52 -0800, "Peter Duniho"
wrote: "Stealth Pilot" wrote in message .. . never hinted that it was immune from anything. True, you didn't hint at it. You just came right out and claimed it. Bob wrote "the range for any aircraft is dependent on power setting", and you wrote "my experience doesnt [sic] support that". When in fact the range for any aircraft IS dependent on power setting. Bob's statement was somewhat inaccurate in that 50% power may or may not produce best range, and may not even be better range than normal cruise. But it's impossible that your experience would contradict that the range is dependent on power setting, because range DOES depend on power setting. peter the time, the duration, that an aircraft can remain airborne is dependent on power setting. not necessarily the range achieved. what I posted were some factual observations. dispute them if you will, they still remain what I observed. ymmv Stealth Pilot Australia |
#22
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"Stealth Pilot" wrote in message
... the time, the duration, that an aircraft can remain airborne is dependent on power setting. not necessarily the range achieved. It affects both. what I posted were some factual observations. dispute them if you will, they still remain what I observed. I'm not disputing your observations. I'm disputing that they have any bearing at the question in hand, and in particular, your claim that they somehow disprove the fact that for any airplane, an increase in range can be had by reducing the power setting below the normal cruise setting. Pete |
#23
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On Mon, 23 Feb 2004 10:27:19 -0800, "Peter Duniho"
wrote: "Stealth Pilot" wrote in message .. . the time, the duration, that an aircraft can remain airborne is dependent on power setting. not necessarily the range achieved. It affects both. what I posted were some factual observations. dispute them if you will, they still remain what I observed. I'm not disputing your observations. I'm disputing that they have any bearing at the question in hand, and in particular, your claim that they somehow disprove the fact that for any airplane, an increase in range can be had by reducing the power setting below the normal cruise setting. Pete ok my last post on this. I had a think about your thought of different cooling drag being the reason for the identical fuel burns at the different airspeeds. If you ever get to fly a Tailwind take up the offer. You will experience an aircraft with a significantly increased induced drag influence compared to the higher aspect ratio Cessnas/commercial stuff that you seem to be basing your comments on. It seems to me that induced drag builds up quicker in the Tailwind at slower speeds than in the commercial offerings. I accept the cooling drag comment but think it is less significant than induced drag as part of the answer. "the fact that for any airplane, an increase in range can be had by reducing the power setting below the normal cruise setting" I will warn you that you are in for a surprise which may cost you the aircraft in the right (wrong) conditions. This was covered ad nauseum in my commercial pilot studies under aircraft performance. I'll give a brief reiteration here. If you have a look at the Cessna POH for the 150M you will find your range profile graph on page 5-15. what you indicate is correct - for the conditions that the graph was made for, which is for zero wind conditions. two pages over you will find a more useful graph which just gives just endurance. you use this for calculating range in the more usual condition of having a wind component. CPL theory (and demonstrated calcs) says that for a tailwind or no wind you fly slower to increase range. for a headwind you fly faster! I'll leave it for you to work out why. Stealth Pilot (...returning to my uni studies) |
#24
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#25
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"Stealth Pilot" wrote in message
... ok my last post on this. You should've stopped a long time ago. I had a think about your thought of different cooling drag being the reason for the identical fuel burns at the different airspeeds. I never made any comment about cooling drag. If you ever get to fly a Tailwind take up the offer. You will experience an aircraft with a significantly increased induced drag influence compared to the higher aspect ratio Cessnas/commercial stuff that you seem to be basing your comments on. You are talking gibberish. It seems to me that induced drag builds up quicker in the Tailwind at slower speeds than in the commercial offerings. "builds up quicker...at slower speeds"? What is that supposed to mean? It is true that there is more induced drag at slower speeds, for any aircraft. It is also true that the exact amount of induced drag will vary from airplane to airplane, and indeed even from weight to weight for the same aircraft. But the nature of the curves for induced drag and parasitic drag are always the same, and they always result in a single L/Dmax airspeed. FOR ANY AIRPLANE. I will warn you that you are in for a surprise which may cost you the aircraft in the right (wrong) conditions. Doubtful. This was covered ad nauseum in my commercial pilot studies under aircraft performance. Something was covered. You should have paid better attention when it was. I'll give a brief reiteration here. If you have a look at the Cessna POH for the 150M you will find your range profile graph on page 5-15. what you indicate is correct - for the conditions that the graph was made for, which is for zero wind conditions. Yes. So? two pages over you will find a more useful graph which just gives just endurance. you use this for calculating range in the more usual condition of having a wind component. Endurance and range are two completely different things. You cannot depend on endurance numbers to provide range numbers, unless you also take into account the differences in airspeed. Best endurance will NOT be the same airspeed as best range. CPL theory (and demonstrated calcs) says that for a tailwind or no wind you fly slower to increase range. for a headwind you fly faster! I'll leave it for you to work out why. Do you have a point? I said several posts ago this exact thing. Sounds to me like you're just making my point for me. Or maybe you're just copying my posts, trying to make it look like you have an original thought. I'm not really sure which. However, it also appears that you are misunderstanding the general truth regarding how to deal with tailwinds and headwinds. For a given no-wind power setting, it is true that you should fly faster (and with more power) in a headwind and slower (and with less power) in a tailwind to compensate. However, you will not achieve the same range as in no-wind conditions. In a headwind in particular, your best range airspeed most likely will still be less than the normal cruise airspeed. It all depends on the headwind, but for typical, light headwinds the change due to wind does not overwhelm the need to fly closer to the L/Dmax airspeed. Even in a headwind, best range airspeed is usually found below normal cruise. It is simply not true that even in a headwind, one needs to fly faster than normal cruise to achieve best range, nor would that be relevant at all to this discussion even if it were. Pete |
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