FIA Massa's Front Wing
- Thread starter Westy
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Fenderman
Rooters Reporter
Scarbs has been thinking about the “flutter” exhibited by Massa's front wing: http://scarbsf1.wordpress.com/2011/10/29/analysis-ferraris-front-wing-flutter/
So have I. The phenomenon of "flutter" is well understood by structural engineers (here's a project for Slyboogy, by the way) since the issue has a resonance (excuse the pun) with some rather spectacular structural failures of bridges.
The most dramatic and perhaps well known of these was the collapse of the Tacoma Narrows Bridge in the USA in 1940. When subjected to wind speeds of around 64kph (approx' 40mph) the central span of the bridge began to oscillate. The investigation into the disaster found that there was a correlation between wind speeds, the aerodynamic characteristics of the structure and the resonant frequency of the deck. At that time of its design and build, civil engineers had either not understood or had not applied knowledge of aerodynamics to the construction of suspension bridges. The cause of the collapse was eventually diagnosed as a consequence of aero-elastic flutter. The disaster was a seminal moment not just for the construction industry but for other fields of engineering as well and the lessons learnt have informed mainstream physics and material science ever since.
I tell you this just to give a bit of background to Ferrari's problem and I am sure that they are well aware of the issues that they are dealing with and certainly don't need me (a humble amateur comfy chair engineer) to explain it to them!
Anyway, where was I? Oh yes, basically any structure will have a degree of elasticity. In other words if a force is applied to the structure it will deform but as the load weakens the structure will tend toward returning to its original shape. A structure will also have an intrinsic resonant frequency, whereby a motion induced in it and the structures reaction (i.e. its attempt to spring back to shape) will repeat . Rather, to use the correct terms, it will vibrate (or oscillate).
So, aero-elastic flutter is a positive feedback mechanism whereby the application of an aerodynamic load - i.e. the flow of air on and/or across it - causes a structure to repeatedly deform - i.e. vibrate, or oscillate.
An analogue of this principle is the shattering of a champagne glass using sound waves. If the sonic frequency is matched with the resonant frequency of the glass, the glass will vibrate since the sound waves are interacting with the molecular structure of the material. If the experiment is continued long enough the vibration will exceed the structural integrity of the glass and it will shatter.
The aero-elasticity of the structure “tries” to rebound but the continued load makes it deform again. A positive feedback loop occurs in the sense that each oscillation adds energy to the system, increasing the rate and strength of the vibration. In other words, if the aerodynamic load continues and is reinforced by the resonant frequency of the structure, then the effect on the structure increases. In the right conditions, the frequency of the vibrations (fluttering) will carry on increasing until such time as the load is removed or, at the extreme end of the process, there is a catastrophic failure of the structure.
It is possible with some materials and in some conditions to tune the load to the resonant frequency, thereby stabilising the oscillations at a specific amplitude (i.e. rate of vibration). An analogue of that effect is feedback used by guitarists to sustain a note for ludicrous lengths of time. When we pluck a string on a guitar to play a note and hold the guitar in front of an amplifier so that the magnetic fields of the pick-up and loudspeakers intersect, this causes the string to continue vibrating without the need to pluck it again. If you move the guitar away the vibration of the string will decrease and the note will decay.
This is essentially what appears to be happening to the Ferrari front wing. As Massa accelerated, the aero-dynamic load on his front wing increased to the point where the load was reinforced by the resonant frequency of the structure. When he braked the load reduced and once the feedback loop was broken the wing returned to a more or less stable state. The fluttering will have been highly undesirable from an engineering point of view because of the threat to the structural integrity of the wing. For the Massa it would have been a bit of handful to say the least, because the wing being unstable meant that the downforce and therefore the handling of the car would have been variable and unpredictable.
In a nutshell, regardless of the legality debate, the prospect of catastrophic failure will certainly be exercising the minds of the Ferrari engineers as well as the undesirable reduction in efficiency of the wing whilst it is “fluttering”.
If you are interested in the science the following entries the Wiki' might be of interest:
http://en.wikipedia.org/wiki/Aeroelasticity#Flutter
http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_%281940%29
So have I. The phenomenon of "flutter" is well understood by structural engineers (here's a project for Slyboogy, by the way) since the issue has a resonance (excuse the pun) with some rather spectacular structural failures of bridges.
The most dramatic and perhaps well known of these was the collapse of the Tacoma Narrows Bridge in the USA in 1940. When subjected to wind speeds of around 64kph (approx' 40mph) the central span of the bridge began to oscillate. The investigation into the disaster found that there was a correlation between wind speeds, the aerodynamic characteristics of the structure and the resonant frequency of the deck. At that time of its design and build, civil engineers had either not understood or had not applied knowledge of aerodynamics to the construction of suspension bridges. The cause of the collapse was eventually diagnosed as a consequence of aero-elastic flutter. The disaster was a seminal moment not just for the construction industry but for other fields of engineering as well and the lessons learnt have informed mainstream physics and material science ever since.
I tell you this just to give a bit of background to Ferrari's problem and I am sure that they are well aware of the issues that they are dealing with and certainly don't need me (a humble amateur comfy chair engineer) to explain it to them!
Anyway, where was I? Oh yes, basically any structure will have a degree of elasticity. In other words if a force is applied to the structure it will deform but as the load weakens the structure will tend toward returning to its original shape. A structure will also have an intrinsic resonant frequency, whereby a motion induced in it and the structures reaction (i.e. its attempt to spring back to shape) will repeat . Rather, to use the correct terms, it will vibrate (or oscillate).
So, aero-elastic flutter is a positive feedback mechanism whereby the application of an aerodynamic load - i.e. the flow of air on and/or across it - causes a structure to repeatedly deform - i.e. vibrate, or oscillate.
An analogue of this principle is the shattering of a champagne glass using sound waves. If the sonic frequency is matched with the resonant frequency of the glass, the glass will vibrate since the sound waves are interacting with the molecular structure of the material. If the experiment is continued long enough the vibration will exceed the structural integrity of the glass and it will shatter.
The aero-elasticity of the structure “tries” to rebound but the continued load makes it deform again. A positive feedback loop occurs in the sense that each oscillation adds energy to the system, increasing the rate and strength of the vibration. In other words, if the aerodynamic load continues and is reinforced by the resonant frequency of the structure, then the effect on the structure increases. In the right conditions, the frequency of the vibrations (fluttering) will carry on increasing until such time as the load is removed or, at the extreme end of the process, there is a catastrophic failure of the structure.
It is possible with some materials and in some conditions to tune the load to the resonant frequency, thereby stabilising the oscillations at a specific amplitude (i.e. rate of vibration). An analogue of that effect is feedback used by guitarists to sustain a note for ludicrous lengths of time. When we pluck a string on a guitar to play a note and hold the guitar in front of an amplifier so that the magnetic fields of the pick-up and loudspeakers intersect, this causes the string to continue vibrating without the need to pluck it again. If you move the guitar away the vibration of the string will decrease and the note will decay.
This is essentially what appears to be happening to the Ferrari front wing. As Massa accelerated, the aero-dynamic load on his front wing increased to the point where the load was reinforced by the resonant frequency of the structure. When he braked the load reduced and once the feedback loop was broken the wing returned to a more or less stable state. The fluttering will have been highly undesirable from an engineering point of view because of the threat to the structural integrity of the wing. For the Massa it would have been a bit of handful to say the least, because the wing being unstable meant that the downforce and therefore the handling of the car would have been variable and unpredictable.
In a nutshell, regardless of the legality debate, the prospect of catastrophic failure will certainly be exercising the minds of the Ferrari engineers as well as the undesirable reduction in efficiency of the wing whilst it is “fluttering”.
If you are interested in the science the following entries the Wiki' might be of interest:
http://en.wikipedia.org/wiki/Aeroelasticity#Flutter
http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_%281940%29
Interesting article on Aerodynamic Flutter.
http://www.cs.wright.edu/~jslater/SDTCOutreachWebsite/aerodynamic_flutter_banner.pdf
http://www.cs.wright.edu/~jslater/SDTCOutreachWebsite/aerodynamic_flutter_banner.pdf
Fenderman
Rooters Reporter
From today's press conference:
Q: Stefano, one of the great mysteries of Formula One at the moment is Felipe Massa’s front wing.
SD: Yes, actually it is very good here in the dark. You can see good sparks. It is adding a lot to the show.
MW: I don’t think it’s a mystery at all.
Q: Alright, maybe it isn’t a mystery. In India you said you were going to investigate and yet it still seems to be doing the same thing here?
SD: Yes, it is true. I mean, it’s pretty obvious. The reality is that we found something that was not correct in terms of the structure of that wing but apparently it seems that there is still a problem. It seems we haven’t fixed the issue yet on that.
Q: Why is it Felipe’s wing only?
SD: I don’t know. The thing is the wing was supposed to go to Felipe’s car. I have got engineers much more expert than me here that know that an effect on a wing can depend on a lot of issues, a lot of things, sorry. It depends on the set-up of the car, depending on tyre pressure and so on. Maybe it is a combination of all these elements for our engineers to understand and react as it is not what we would like to see.
Q: Is it uncomfortable to drive. Does Felipe feel that?
SD: No.
Rad Booton (Rootersport):
Q: Stefano, one of the great mysteries of Formula One at the moment is Felipe Massa’s front wing.
SD: Yes, actually it is very good here in the dark. You can see good sparks. It is adding a lot to the show.
MW: I don’t think it’s a mystery at all.
Q: Alright, maybe it isn’t a mystery. In India you said you were going to investigate and yet it still seems to be doing the same thing here?
SD: Yes, it is true. I mean, it’s pretty obvious. The reality is that we found something that was not correct in terms of the structure of that wing but apparently it seems that there is still a problem. It seems we haven’t fixed the issue yet on that.
Q: Why is it Felipe’s wing only?
SD: I don’t know. The thing is the wing was supposed to go to Felipe’s car. I have got engineers much more expert than me here that know that an effect on a wing can depend on a lot of issues, a lot of things, sorry. It depends on the set-up of the car, depending on tyre pressure and so on. Maybe it is a combination of all these elements for our engineers to understand and react as it is not what we would like to see.
Q: Is it uncomfortable to drive. Does Felipe feel that?
SD: No.
Rad Booton (Rootersport):
For anyone who wants a classroom style explanation of natural frequency and resonance.
http://www.cs.wright.edu/~jslater/SDTCOutreachWebsite/nat_frequency.htm
Its the same principle which explains why opera singers are able to shatter crystal goblets with thier voice. If they can blast out a note at the natural frequency of the item then resonance is induced. Given that the crystal has an extremely minute degree of elasticity what we effectively see is an explosion, rather than a flutter.
http://www.cs.wright.edu/~jslater/SDTCOutreachWebsite/nat_frequency.htm
Its the same principle which explains why opera singers are able to shatter crystal goblets with thier voice. If they can blast out a note at the natural frequency of the item then resonance is induced. Given that the crystal has an extremely minute degree of elasticity what we effectively see is an explosion, rather than a flutter.
Fenderman
Rooters Reporter
... it is possible to generate a sound wave of the right frequency and amplitude to set a glass vibrating at a constant rate without it breaking. It is also possible, and if you've never tried it, quite easy to make a glass produce a note because of the same phenomenon. Lick your finger and run it around the rim of glass. Start slowly and with a light pressure. Carefully increase speed and pressure until it produces a note. Maintain that speed and pressure and the glass will continue to "sing". Lift your finger and the note will continue momentarily, decaying as the glass returns to its stable state.
If one were to look at a super slow motion video of the glass one would see the glass "rippling" with the vibrations. I'll try to track down a video clip ... there's just got to be one on youtube!
If one were to look at a super slow motion video of the glass one would see the glass "rippling" with the vibrations. I'll try to track down a video clip ... there's just got to be one on youtube!
... it is possible to generate a sound wave of the right frequency and amplitude to set a glass vibrating at a constant rate without it breaking. It is also possible, and if you've never tried it, quite easy to make a glass produce a note because of the same phenomenon. Lick your finger and run it around the rim of glass. Start slowly and with a light pressure. Carefully increase speed and pressure until it produces a note. Maintain that speed and pressure and the glass will continue to "sing". Lift your finger and the note will continue momentarily, decaying as the glass returns to its stable state.
If one were to look at a super slow motion video of the glass one would see the glass "rippling" with the vibrations. I'll try to track down a video clip ... there's just got to be one on youtube!
...and this illustrates perfectly the difference in the properties of crystal and glass. The other slightly mind-boggling thing is that glass is a liquid.
Hmm. I don't see how that is a historical first as claimed by the video. I saw this done on a children's education program about 25 years ago. It might even have been Blue Peter.
[Edit] oh, great video sportsman. Thanks for sharing.
[Edit] oh, great video sportsman. Thanks for sharing.
Fenderman
Rooters Reporter
Still trying to find a super slow mo
... at the right temperatures. Which actually applies to all materials. Water has the unique ability to be in liquid, gaseous and solid form at the same time and temperature - I've forgotten the science, I just remember that bizarre fact.
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