User talk:Pilot576

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Hello, Pilot576, and welcome to Wikipedia! I hope you like the place and decide to stay. Here are some pages that you might find helpful:
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Dolphin ( t ) 12:40, 1 May 2023 (UTC)

True airspeed
Hi Pilot576

In four edits to True airspeed you have altered an important equation in such a way that it doesn’t conform to the equation presented in the cited source: section 3.8 of Aerodynamics by L.J. Clancy. I have reverted your edits to restore the correct version but on each occasion you have again altered it to be incorrect again. Your four edits are: diff1, diff2, diff3, diff4. One of Wikipedia’s most important objectives is that all information should be able to be independently verified by being traced to a reliable published source. (See WP:VERIFY.) When you alter an article so that its information no longer conforms to what is published in the reliable source, it is unacceptable. Another of Wikipedia’s objectives is that when a User makes a change, that User’s intention or reasoning should be visible. Edits should be accompanied by an edit summary. None of your edits were supported by an edit summary so no-one has any idea as to why you made your changes. You can now explain your thinking on true airspeed by replying to this discussion thread. If you continue as you have in the past it will begin to look like deliberate vandalism. Dolphin ( t ) 13:27, 1 May 2023 (UTC)


 * Hello Dolphin 51
 * I apologize for the misunderstanding. I have recently conducted a mathematical study on finding True airspeed mathematically using indicated Airspeed and on each occasion using the previous unedited formula, my result came back that True airspeed is of a lesser value than Indicated airspeed. This is however, as you surely know, not possible. However, when using the other formula that i edited in, it worked, and gave me a reasonable, larger value.
 * I merely edited the equation so i could get a reply like yours, so i can address my concern.
 * I apologize the confusion this may have caused.
 * If you could, however, help me out and tell me why this may be the case, i would greatly appreciate it.
 * (For context here are my given data:
 * Indicated Altitude: 2667  m
 * Indicated Air Speed (IAS): 128.611  m/s
 * Current Barometric Pressure: 101100  Pa
 * Wind Speed: 3  m/s
 * Wind Direction: 260°  = 4.53786 radians
 * Temperature: 11°C)
 * with these, i need to find TAS using only formulae.
 * Thank you! Pilot576 (talk) 17:32, 1 May 2023 (UTC)


 * Thanks very much for your prompt reply. I can give you a detailed explanation of how to find TAS using the formula. I will do so in the next few hours. Cheers! Dolphin ( t ) 22:20, 1 May 2023 (UTC)
 * Thank you so much! Pilot576 (talk) 05:46, 2 May 2023 (UTC)
 * Hi again! Regarding this, i was wondering if you could help me out once more... Apart from these various formulae, is there any other way using more challenging mathematics (e.g. not just substitution into formulas) that can be used to measure the True Airspeed and Ground Speed of an aircraft? Perhaps angle of the wind or something? I'm not sure but it generally has to be pretty high level maths. Would love to hear any ideas! Thanks again :) Pilot576 (talk) 15:32, 6 May 2023 (UTC)


 * Go to the References at the foot of the article Static pressure and you will see two .pdf files with articles by William Gracey of NASA. These publications will help you.
 * These URLs haven’t been updated since 2008 and they no longer work. If you Google for the obvious keywords you will find these technical publications by Gracey. I will update the two URLs in coming days. Dolphin ( t ) 22:45, 6 May 2023 (UTC)
 * I have now updated the URLs for these two .pdf files. They should work now. Dolphin ( t ) 07:18, 7 May 2023 (UTC)

Worked example
To use the formula to find TAS we need EAS and air density (ρ rho). Your question does not present either of these two figures so we must obtain them.

Firstly, we have IAS of 250 knots (463 km/hr; 128.611 m/s; 39.189 ft/s). The difference between IAS and EAS reflects the error in sensing the air pressure surrounding the aircraft using a static port somewhere on the surface of the aircraft. The error is small so we can safely assume that EAS is the same as IAS.

Next we must obtain the air density (ρ).
 * pressure altitude 2667 m (8753 ft)
 * sea level pressure 1011 hPa
 * pressure altitude changes by about 10 m for each hPa of pressure. If the indicated altitude is 2667 m with the altimeter sub-scale set to 1011 hPa, then with the sub-scale set to standard pressure of 1013 hPa the pressure altitude will be 2647 m.

In the standard atmosphere:
 * at 2500 m the pressure ratio (δ delta) is 0.7371 (taken from a table of values in the standard atmosphere)
 * at 3000 m the pressure ratio (δ) is 0.6919 (taken from a table of values in the standard atmosphere)
 * using linear interpolation: at a pressure altitude of 2647 m the pressure ratio (δ) is 0.7238 and the air pressure is 733 hPa (calculated by 0.7238 x 1013 hPa.)

Temperature is 11 C (284 K) and standard temperature at sea level is 15 C (288 K) so the temperature ratio (θ theta) is 0.9861.

At this point we can introduce density ratio (σ sigma) and make use of the formula: δ = σ θ or σ = δ / θ

The temperature ratio is 0.9861, and the pressure ratio is 0.7238, so the density ratio (σ) is: 0.7238 / 0.9861 which is 0.7340. The density is 0.8992 kg/m3 (calculated by 1.225 x 0.7340 because standard sea level density is 1.225 kg/m3)

We now have all the necessary information so your question can be asked as follows:

________________________________________________________________________

If EAS is 250 knots (128.6 m/s) and air density is 0.8992 kg/m3, what is TAS?

The density ratio is 0.8992 / 1.225 which is 0.7340. The square root of the density ratio is the square root of 0.7340 which is 0.8567.

We divide 250 knots EAS by 0.8567 and the result is 291.8 knots TAS.

So the answer is 292 knots (540 km/hr; 150 m/s; 45.7 ft/s).

Let me know if you have questions about any of this. I will be happy to explain. Dolphin ( t ) 12:56, 2 May 2023 (UTC)


 * Thank you so so much! If its not too much could you maybe give me the exact formulas used and their names (as i have to reference them)... if possible i would greatly appreciate it! Pilot576 (talk) 15:29, 2 May 2023 (UTC)
 * I also wanted to ask, (hopefully im not bombarding you with questions..), i had previously used these following formulas:
 * The barometric formula: P= P0* (1-(L*h/T0))^(g0*M/(R*L))
 * Air density formula: rho= P/(R*T)
 * TAS formula (the incorrect one in this case)
 * GS formula: GS= sqrt((horizontal component)^2 + (vertical component)^2)
 * is there any way that i can still use these but with the correct TAS formula..? Pilot576 (talk) 15:36, 2 May 2023 (UTC)


 * The following equations are all versions of the equation of state. Wikipedia also calls them the classical ideal gas law:
 * rho= P/(R*T)
 * δ = σ θ
 * σ = δ / θ


 * My definition of ground speed is the rate at which the length of a vehicle's track across the ground is increasing. Ground speed is mostly used as an aid to aircraft navigation; especially when determining how long it will take to reach a destination or waypoint. If an acrobatic aircraft is diving vertically I would say its ground speed is zero because its track is a stationary point on the ground. Your formula sqrt ((horizontal component)^2 + (vertical component)^2) is what I would call the speed relative to the Earth's surface. If an aircraft is diving vertically at 50 metres per second I would say its ground speed is zero but its speed relative to the Earth's surface is 50 metres per second vertically downwards.


 * I called δ, σ and θ the pressure ratio, density ratio and temperature ratio respectively. On reflection, I think the correct names are relative pressure, relative density and relative temperature.


 * You aren't bombarding me with questions. Feel free to keep asking. Dolphin ( t ) 12:31, 3 May 2023 (UTC)
 * ok thanks so much! Also, is it possible for TAS to be less than IAS? i know GS can be less but not sure about TAS... Pilot576 (talk) 03:51, 4 May 2023 (UTC)


 * Firstly, let's ask the question "Is it possible for TAS to be less than EAS?" The answer is "Yes. When the density of the air is greater than sea level density (rho 0) in the standard atmosphere (1.225 kg/m3)." This is evident by examining the formula at the origin of our discussion. It will be rare for the density to be greater than sea level density, but not impossible. If the air pressure is greater than 1013 hPa and temperature is less than 15 C then density will be greater than 1.225; but this is only likely to happen around sea level or lower, and at cold temperatures. So when an aircraft is taking off near sea level in cold temperatures (below 15 C) it is likely that TAS will be very slightly less than EAS for a few seconds until the aircraft gains altitude and pressure falls below 1013 hPa.


 * Secondly, let's examine the question "What is the difference between EAS and IAS?" These two airspeeds are usually very similar. Designers and manufacturers of aircraft intended for commercial operations (such as transport category and normal category aircraft) are required to locate the static ports so that the position error is small - this guarantees that indicated altitude will be reasonably accurate and the aircraft won't present a hazard to other aircraft assigned a slightly higher or lower cruising altitude. If the first attempt to position the static port fails, the designer or manufacturer must try a different location, and keep trying until finding a position that causes the error to be within the specified limits. If we assume that EAS and IAS are approximately equal, we conclude the same answer as shown above. <i style="color: green;">Dolphin</i> ( t ) 13:25, 4 May 2023 (UTC)
 * Ok! Thank you so so much again youve been very helpful! Pilot576 (talk) 03:46, 5 May 2023 (UTC)