Questions tagged [measurement]

Questions about various forms of measurement used in aviation

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What type of probe can measure induced drag in the wake?

Induced drag can be measured from velocity preturbation in Treffz plane. In Treffz plane what velocity direction is important for induced drag, vertically down, lateral(horizontal, "spanwise&...
user707264's user avatar
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0 answers
57 views

What are the common sensors/ways that reverse thrust is measured for turbines?

I am looking for a sensor to measure reverse thrust on a small hobby turbine engine, a jetcat p100-rx. I did not find clear ways industry measures reverse thrust from previous searches online and was ...
Billy Dolan's user avatar
1 vote
1 answer
87 views

What is the EGT probe output tolerance?

What is the 'average' or general tolerance (+/-) for EGT probes output on a 'typical' commercial turbofan engine?
MFCTenor1's user avatar
0 votes
0 answers
80 views

Sensors used on a blade

How to measure the strain, temperature and rotational dynamics on a running engine fan blade? How can you do the experiment?
user67835's user avatar
2 votes
2 answers
365 views

Modern method to verify speed of a homebuilt aircraft

Summary: In 2001, airspeed of homebuilt aircraft was calculated by flying in a ⊔-shape and using trigonometry to subtract wind effects. Now that we have portable computers, is there a more modern ...
Zaz's user avatar
  • 1,559
3 votes
1 answer
352 views

How long should a pitot tube extend from the wing?

It seems that most of the pitot tubes are "L" shaped. However, there are some pitot tubes that shapes like a straight pipe. I am wondering that, for a straight pitot tube installed on the ...
Faito Dayo's user avatar
-3 votes
1 answer
164 views

If the altitude of the aircraft is given by the pitot tube, in icing condition with heat on, how is real altitude /speed interpretation done? [duplicate]

If the altitude of the aircraft is given by the pitot tube, in icing condition with pitot heat on how is real altitude /speed interpretation done? Because the air density and temperature is not ...
George Geo's user avatar
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-3 votes
1 answer
218 views

Fighter Jets speed [duplicate]

How does an aircraft measures (or calculates) its speed while in air? Which equipment or sensors are used for measurement of speed? Does it takes Earth as a reference frame for its speed measurement ...
scico111's user avatar
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-4 votes
1 answer
164 views

Viewing and capturing real time values of Tachometer measuring instrument on television set and computer monitor in Aircraft and Automobiles [closed]

https://en.wikipedia.org/wiki/Tachometer https://patents.google.com/patent/DE2500376A1/en Is it possible to view and capture real time values of a Tachometer in Aircrafts, Automobiles, Spacecrafts, ...
Prashant Akerkar's user avatar
8 votes
4 answers
2k views

Why are pitot-static measurements preferred over other velocimetry techniques?

I believe hot wire anemometers (HWA, frequently used in wind tunnels to measure flow velocity) or other sensitive techniques could be used to determine the airspeed. Are there specific reasons for why ...
William R. Ebenezer's user avatar
3 votes
1 answer
355 views

How does a synchro resolver converter work?

There are Synchro converters or transducers used on aircraft to measure angle of attack using 3 sinusoidal inputs. I could not understand where these 3 inputs come from and what angle information is ...
scico111's user avatar
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10 votes
2 answers
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What is the effect of altitude on true airspeed?

I know that wind is taken into account when we compute the TAS(true airspeed) and GS(ground speed). However what is the relationship between the TAS and altitude? For example: What is the true ...
Volkan Eroğlu's user avatar
1 vote
1 answer
808 views

What is the relation between altitude and vertical speed?

I recently saw 2 graphs on a flight path on BBC, shown below. For those interested, it's the path of the recently crashed Boeing 737 max flight ET302, but that's irrelevant to my question. My ...
ElRudi's user avatar
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2 votes
1 answer
153 views

Pitot tube model

EDIT: Background on my application I am making a few measurement models for an extended Kalman filter (EKF). The EKF is meshing an INS and a GPS currently, but the GPS update rate does not update ...
Boto's user avatar
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12 votes
2 answers
1k views

How is the camera positioned for these plane-to-plane Schlieren images of shock waves?

These two popular press articles discuss the use of schlieren photography to image shock waves of jets during flight using a special schlieren camera on a third plane. Gizmodo: NASA Captures First-...
uhoh's user avatar
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3 votes
2 answers
3k views

How to calculate DDM in a ILS dual frequency system?

I'm working in a project where I have to process ILS baseband signals. I have no problem obtaining DDM value from single frequency signals, nor the individual components of a dual frequency signal (...
Leroy's user avatar
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1 vote
1 answer
5k views

Where is the wing sweep angle measured from?

If you look at a 747 planform wing you see something like this: In several aerodynamics and aircraft design text books they use the wing sweep angle as an important parameter to measure the wing ...
XF-91's user avatar
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4 votes
2 answers
462 views

How to compare two SFCs, one in thrust, the other in power (both turbofans)?

I want to compare some recent turbofan engines in terms of fuel efficiency, particularly the PW535A and FJ44-4. I found the SFC for the PW535A to be 0.44 lb/h/lbf. I couldn't find anything on the ...
rational-pi's user avatar
11 votes
2 answers
7k views

How is windspeed scaled in wind-tunnel tests?

Let's say you have a scale model that is 1:10th the size of the real thing. You want to test this in a wind-tunnel. Do you also scale down the windspeed 10x? Why or why not? I would think it has to ...
DrZ214's user avatar
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1 vote
1 answer
992 views

What is the unit for ground speed reported by ADS-B?

Strangely enough, I'm having trouble finding the unit reported by ADS-B on the Internet. Many sites simply refer to it as "ground speed". Is it measured in KPH?
Ken - Enough about Monica's user avatar
0 votes
1 answer
158 views

How to find the measurement of how far Tail plane to Center of gravity of the aircraft?

How do you find the measurement of Piper Archer Tail Plane distance to the center of the gravity. Google really doesn't help me... maybe you guys know some website that has databases of small ...
Aishve Torah's user avatar
5 votes
3 answers
6k views

How does Kalman filtering work in inertial navigation systems?

As far as I understood it correctly most INS-systems use a Kalman filter to compensate measurement errors. I would like to know: Does the Kalman filter compensate the errors from all the onboard ...
traducerad's user avatar
8 votes
1 answer
18k views

How is the wind direction and wind speed measured in flight?

Most large aircraft have a wind direction and wind speed indicator. How is this measured? The vector difference between TAS and ground speed? How accurate is this? In the below picture (taken from ...
Daniel R's user avatar
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6 votes
2 answers
2k views

How is horsepower measured for aviation piston engines?

As far as I can tell, aviation piston engine power output is typically measured in HP (horsepower). Automotive engine power output is typically measured by running the host vehicle on a rolling road, ...
Digital Trauma's user avatar
3 votes
2 answers
518 views

Is there an explanation for the measurement system used in aviation? [duplicate]

Why is speed measured in knots (as opposed to kmp/h or mp/h), and distances in nautical miles? Is there a reason for following such a system?
Madhav Sudarshan's user avatar
3 votes
4 answers
3k views

Is there a database of airport ceilometer raw data?

I am interested in obtaining raw ceilometer data, to test some cloud/aerosol layer identification algorithms. Is this type of data freely available or will I need to ask for it directly from the ...
luka's user avatar
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1 vote
1 answer
194 views

Are there any companies that use atom interferometers in aircraft?

Are there any companies that use atom interferometers in aircraft? If so, are they used for navigation? If not, is it possible to assemble it? Here is the link from wiki Atom interferometer and link ...
Chad Meng's user avatar
2 votes
1 answer
993 views

Still using knots, nautical miles, inches of Hg. Is that impossible to switch to SI units? [duplicate]

Why doesn't the aviation industry use SI units?. I believe only a few countries use meters and other SI units in air transportation, including India and China (please correct if wrong). Using kts ...
mins's user avatar
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13 votes
3 answers
9k views

Does European airspace use the metric system?

I figured this was probably a no brainer, since Europe uses the metric system, I assume the airspace does... But then I remembered that aviation likes international standards, and I know the US uses ...
Jae Carr's user avatar
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3 votes
2 answers
888 views

What do aerodynamic flow cones measure?

This picture of an Airbus A350 test aircraft shows multiple instruments on the flap fairings, wing fairing and on the empennage: Source: A380_TLS_A350 AIB199GG (high-res version) They are being ...
florisla's user avatar
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31 votes
1 answer
17k views

Which external instruments are visible on the A350's nose section?

Most pictures of airliner's nose sections show small dark tube- or fin-shaped instruments sticking out of the fuselage below the cockpit windows. For example this Airbus A350 shows them well: ...
florisla's user avatar
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16 votes
4 answers
73k views

What is the coordinate system used in an Aircraft?

I know that from nose to tail the aircraft is divided by STA (station). At least for Boeing and Airbus this is the case but I am not familiar with other manufacturers. However, there is also two ...
esé's user avatar
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29 votes
4 answers
15k views

Why doesn't the aviation industry use SI units?

This is a followup to What is the measurement system used in the aviation industry? and related to this question from History. I can understand the arguments as to why adoption of SI units would not ...
asheeshr's user avatar
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24 votes
4 answers
47k views

What is the measurement system used in the aviation industry?

I saw this question from History Stack Exchange and noted that the US is still using the imperial measurement system such as feet, miles and pounds. Given that a plane may need to fly from one ...
Question Overflow's user avatar
6 votes
1 answer
4k views

What are these acceleration parameters produced by the Inertial Reference System?

Following acceleration parameters are transmitted from Inertial Reference System (IRS) to Flight Control System (FCS): Flight Path Acceleration Along Track Acceleration Cross Track Acceleration ...
ToUsIf's user avatar
  • 1,143
20 votes
3 answers
13k views

Who decides what measurement units are used for altitude, and why is there no standard?

I know that some countries (Russia and China for instance) use meters to measure altitude while the rest of the world uses feet. Why isn't this standardized around the world? I guess all modern ...
Haris's user avatar
  • 1,017
15 votes
2 answers
1k views

How can I estimate the minimum runway needed to take off with a hang glider?

I'm interested in short, or trick, take-offs - such as from platforms, tall trees, etc. I think that I should have a wind speed and direction measure an understanding of my wing surface area This ...
New Alexandria's user avatar