Questions tagged [vibration]

Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. The oscillations may be periodic such as the motion of a pendulum or random such as the movement of a tire on a gravel road.

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55 votes
6 answers

Why do most radial engines use an odd number of cylinders?

To help suppress vibration, most 'V' and 'horizontal' engines use an even number of cylinders as closely opposed as possible. Radial engines are well known for excessive vibration. For some reason ...
jwzumwalt's user avatar
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12 votes
7 answers

How much do propellers stutter?

A photo in EAA's monthly magazine shows one propeller blade as a dozen distinct images rather than the usual smooth motion blur. One explanation (this answer appears to have been deleted) for this is ...
Camille Goudeseune's user avatar
9 votes
5 answers

Do aircraft cabins have suspension?

On cars, we have 'shock absorber' suspension that decouples the passengers and loads from the road vibrations, bumps etc. On planes do we have any form of suspension that decouples the passengers &...
midnightBlue's user avatar
8 votes
1 answer

What is the range of frequencies of vibration in a helicopter due to the main rotor alone?

Vibration in helicopter can be caused by many different reasons. I am interested to know what is the range of frequencies of vibration due to the main rotor alone? I understand that it would depend ...
Creator's user avatar
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5 votes
1 answer

What could cause lower torque than normal during cruise in a King Air 300?

At approx FL200 in our King Air 300 we experience a vibration and notice the torque drop for both engines. The torque stays about 10% lower than normal in cruise. The vibration is intermittent and ...
user44149's user avatar
4 votes
1 answer

Why this inertial regulator of dragonfly wing pitch reduces self-excited coupled flapping and feathering vibrations and improves gliding flight speed

The pterostigma of insect wings an inertial regulator of wing pitch is linked in this answer to Why do dragonflies have these special little spots on their wings? (open access copy here) The Summary ...
uhoh's user avatar
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3 votes
1 answer

PA28 Archer 2 Circa 1986 - Noisy Engine

100 hours ago, a group-owned PA28 Archer II Circa 1986, 180hp plane had its engine rebuilt after 2500 hours. There had been no problems with the aircraft during the 2500 hours. Since the rebuild, the ...
John B's user avatar
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3 votes
2 answers

How is vibration isolation achieved in helicopters?

In many helicopters, they say they have reduced the vibrations significantly, but how is this isolation being achieved?
NitinG's user avatar
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3 votes
1 answer

Why are acoustic power loss never taken in account?

At university (I did mechanical engineering) I attended several courses in which energy balance was considered (e.g. thermal machines, electric machines, CFD...). Each time a machine efficiency was ...
temporary_pigeon's user avatar
3 votes
2 answers

Why in a CFM56-3 is vibration measured in displacement for N1 and in velocity for N2?

N1 is measured in mils (thousandth of an inch) and N2 is measured in IPS (inches per second). Why are different methods used?
Anugerah Radifan's user avatar
3 votes
3 answers

Is there any alternative to isolating the vibration of an ultralight engine other than using engine mounts?

Is there any alternative to isolating the vibration of an ultralight engine other than using engine mounts?
David Teahay's user avatar
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2 votes
2 answers

Main structural (and any other) impact of hard landing

I was reading this question related to the parts suffering the most G forces. Reflecting about that question I question myself about hard landing, which is not a normal operation. So, my especific ...
Trebia Project.'s user avatar
1 vote
1 answer

What is the difference between buffeting and wake galloping?

I am interested in flow-induced vibration and confused between buffeting and wake galloping. As far as I have studied, both phenomena are the vibration of an object with another object in front of it. ...
Pithipol Kuakoon's user avatar
1 vote
0 answers

What are the expected vibration frequencies in a co-axial rotor system with contra-rotating propellers?

I am trying to understand the frequency spectrum of a co-axial rotor system. Form now i have a RC helicopter with two sets of three gear systems arranged in parallel, The number of teeth are 7,23,27) ...
Nilesh Naik's user avatar
0 votes
1 answer

Does the “Torque-Induced Precession” of the two rotor blades cause the V-22 Osprey to tear itself apart

Concerning Bell Boeing V-22 Osprey Aircraft: Does the “Torque-Induced Precession” of the two rotor -- 3-blade, propellers cause the V-22 Osprey to become unstable. In the case of a helicopter the ...
Symmetry's user avatar