|WikiProject Aviation / Aircraft||(Rated Start-class)|
"The airspeed indicator is especially important for monitoring V-Speeds while operating an aircraft. However, in large aircraft, V-speeds can vary considerably depending on airfield elevation, temperature and aircraft weight. For this reason the coloured ranges found on the ASIs of light aircraft are not used - instead the instrument has a number of moveable pointers known as bugs which may be preset by the pilot to indicate appropriate V-speeds for the current conditions."
Most small aircraft in the US do not have moveable pointers. Indicated stall speed does not vary with altitude and temperature, only weight, and only slightly within the acceptible (certified) range. I think this needs clarification.
Confusion VA vs VNO ?
One of the most important V Speeds that is not marked on airspeed indicators for light aircraft is VA (maneuvering speed, the speed at which full and abrupt control movement can be applied without causing structural damage.
From the V speed page : VNO is the speed at which structural damage can occur, VA being the speed at which stall can occur during sharp turns. So either this sentence is wrong or the V_speeds page isn't very clear--Yitscar 15:04, 22 October 2007 (UTC)
From a few lines up in the article:
"The red line is preceded by a yellow band which is the caution area, which runs from VNO (maximum structural cruise speed) to VNE."
You're exactly right. A plane cruising at VA will stall before it exceeds the positive-G load limit, but on most aircraft pushing forward can still exceed the (usually lower) negative-G limit. There also can be other aerodynamic forces below VA that can damage the airplane, such as the lateral forces on the vertical stab that brought down American Airlines 587. Under VNO, however, an airplane in the "clean" configuration (no flaps) can handle any aerodynamic forces, wether they come about from wind gusts or control inputs. And, unlike VA, VNO is marked on the airspeed indicator, by the top of the green arc. The idea that "you can't break the airplane below maneuvering speed" is a common, potentially dangerous misconception. 188.8.131.52 (talk) 05:35, 28 February 2008 (UTC)
Fair use rationale for Image:Airspeed tape.png
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Lift Reserve Indicator
I questions whether this section should be part of Airspeed indicator or a totally new article. A LRI is not an airspeed indicator. It also seems that the section "teaches" use of a LRI; Wikipedia is NOT a teacher. There might also be an element of commercial promotion in the section. Comments from other users welcomed.Geoffrey Wickham (talk) 04:50, 25 March 2008 (UTC)
I wrote the current iteration on the LRI. I do not sell them, nor do I intend to. I do own and fly a general aviation airplane and the photo of the LRI was taken by me of the LRI in my airplane. I researched the LRI and had it installed in my airplane because I wanted to enhance the safety of my flying for short field operations. I personally believe it has tremendous safety value for any pilot who is willing to understand what it does it and use it.
As to Wikipedia not being a teacher: I was under the impression that uninformed people come to wikipedia to learn about things they do not know. That is the very essence of what an encyclopedia is, isn't it? To the uninformed, every article in Wikipedia is a teaching article. How can you make the broad statement that Wikipedia is NOT a teacher? Wikipedia is a teacher to the uninformed, and has no value as anything else. As to the teaching part of the LRI: The LRI is one of the only flight instruments that is not complete until the pilot makes the final adjustment based on flight tests with the airplane and the instrument. This is a critical part of the understanding of this instrument and its interaction with the pilot and the airplane. It must not be left out if true understanding is to be imparted.
As to the having then LRI as a seperate article: I did my work on the LRI in this artilce because someone else had started it and had done so poorly. I am ok with making it a seperate article, but I don't know how to do that. I do know how to edit and improve a poorly written article that already exists. Some of the things I changed were: 1. There was a photo of a machmeter, not a photo of a Lift Reserve Indicator. I added a photo taken from my plane. 2. The start of the article was poorly written, and did not really tell the reader what the LRI is or how it works. I did both. 3. The article was biased against the LRI for any and all uses. I pointed out how the LRI imparts information to the pilot, and how that information is helpful in different flight applications, and how that information differs from the information provided by the ASI.
Explain how V2 turns into V
To the author:
The speed indicator operation is based on measuring the difference between stagnation pressure and static pressure. This difference is the dynamic pressure, given by 0.5*rho*V2. In an S&L flight at sea level the dynamic pressure is thus proportional to V2. There must be some mechanical trick inside the indicator that makes its dial turn proportional to V rather than to V2.
I think this point is important enough to be explained in the article and I suggest you add a paragraph dedicated to it. (Myself, I don't know the answer.)