Can I Calculate Engine Speed from Sound Frequency Inside an Airplane?

In summary, the conversation discusses the possibility of determining the speed of an aircraft engine from the sound it makes inside the plane. The speaker has an audio analysis program and can determine the frequency of the sound, but needs more information about the engine in order to accurately determine its speed. Other participants in the conversation suggest methods such as using a tachometer or measuring the pulses per minute, but it is noted that these methods may not provide an exact measurement without knowing the specific details of the engine. The potential applications of using sound frequency to determine speed are also mentioned.
  • #1
glennpagano
17
0
I am in the airport right now and I was wondering if there is someway to determine the speed of the aircraft engine from the sound the engine makes inside the plane. I have a audio analysis program and I can determine the frequency of the sound inside the airplane. Is there any way to determine the speed of the engine this way?
 
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  • #2
Bump...anyone?
 
  • #3
What engine? Turbine or Piston? Assuming Turbine, Which Turbine Manufacturer? Which Model?

What are you "hearing"? Turbine Compressor whine? Turboprop prop wash noise?

Assuming higher pitch with higher RPM?

I'm a Private Pilot, "FAA/Military" Simulators being my only "turbine time". If I recall correctly, most turbine instrumentation reflects percentage of max rpm, not typically "actual values".

I believe the answer to your question is "yes", IF, you knew more about the specific powerplant and it's specific aircraft application.
 
  • #4
You can tell the speed of an engine from the sound. Don't know exactly how, but it's terribly complicated.
 
  • #5
I would say the highest frequency is the frequence obtained but the frequence of a rotor blade passing a stator. Now, if you knew how many of each...
 
  • #6
I am pretty sure I would be hearing the turbine whine. When I looked at the analysis I noticed that there were 2 frequency peaks. One was 245.185 Hz and the other was 632.347 Hz. Now I am just going to try and think about how I can somehow apply these numbers to the turbine speed.
 
  • #7
Your peaks correspond to 14,711 and 37,940 pulses per minute, so may represent an rpm. Without knowing the actual engine rpm, it would be hard to say though. Either or both peaks could be the result of constructive interference of the pulses generated by several parts of the engine (compressor blades, turbine blades, combustion fluctuations, etc.) leading to the occurance of "beats" that may or may not be indicative of the engine speed. Once the ratio between the pulses and the actual engine rpm is known, it could be used to measure the rpm.
 
  • #8
I worked at a power plant, and this guy had a tachometer that figured out how fast the steam turbine was spinning just based on its vibrations. It was some small magnetic thing that he placed on the turbine and BAM! there was the reading. It looked old school, too. I don't even think it was digital (although can't remember for sure). Man I was blown away by that thing!
 
  • #9
mender said:
Your peaks correspond to 14,711 and 37,940 pulses per minute, so may represent an rpm. Without knowing the actual engine rpm, it would be hard to say though. Either or both peaks could be the result of constructive interference of the pulses generated by several parts of the engine (compressor blades, turbine blades, combustion fluctuations, etc.) leading to the occurance of "beats" that may or may not be indicative of the engine speed. Once the ratio between the pulses and the actual engine rpm is known, it could be used to measure the rpm.

How did you determine the pulses per minute? I think this would be really neat if using the frequency of something to determine the speed of it. It can be used in many places. These numbers also take into account the frequencies of both engines because they were not running at the same speed. I know these because I heard a "beat" interference between the two.
 
  • #10
glennpagano said:
How did you determine the pulses per minute? I think this would be really neat if using the frequency of something to determine the speed of it.

"One was 245.185 Hz and the other was 632.347 Hz."
"The hertz is equivalent to cycles per second."

To find the number of pulses per minute, multiply the frequency as measured in hertz by 60.
 

What is the speed of an airplane engine?

The speed of an airplane engine can vary depending on the type of engine and the aircraft it is powering. Generally, the speed of a piston engine can range from 2,000 to 2,500 revolutions per minute (RPM) while a turbine engine can range from 10,000 to 25,000 RPM.

How does the speed of an airplane engine affect flight?

The speed of an airplane engine is directly linked to the power and thrust of the aircraft. A higher engine speed means more power and therefore a faster and more efficient flight. However, too high of an engine speed can also cause damage and overheating, so it must be controlled carefully by the pilot.

What factors can affect the speed of an airplane engine?

The speed of an airplane engine can be affected by a variety of factors such as altitude, air density, temperature, and the weight of the aircraft. These factors can impact the performance and efficiency of the engine, resulting in changes in speed and power.

How is the speed of an airplane engine measured?

The speed of an airplane engine is measured in revolutions per minute (RPM). This is typically displayed on the engine's tachometer, which is a gauge that shows the number of rotations the engine is making per minute. Some modern aircraft also have digital displays that show the exact RPM of the engine.

Can the speed of an airplane engine be controlled?

Yes, the speed of an airplane engine can be controlled by the pilot using the throttle. The throttle controls the amount of fuel and air that is fed into the engine, which in turn affects the speed and power of the engine. Pilots must continuously monitor and adjust the engine speed during flight to maintain a safe and efficient speed.

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