Discussion:
Flexing aero
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Bobster
2017-07-18 08:27:46 UTC
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Sky showed some pictures of the Red Bull car that suggest they have some flexing parts on their front wing.

Pat Symonds expanded on this by saying that ALL teams have front wings that are legal in as much as they pass the FIA tests. The FIA tests place specific loads at specific points. All teams design their wings to satisfy the tests - which means that some parts may still flex.

In the case of the Red Bull it is flaps on the end plates that seem to move down in order to create a seal with the ground.

Red Bull were under the spotlight - by SKY, not by FIA - but I inferred from Symonds' comments that other teams might also have parts that are moving on wings that pass the FIA tests.
John
2017-07-18 20:03:59 UTC
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Have never read a reasonable explanation on why "flexing" is banned. Probably because there isn't one like so many others.
~misfit~
2017-07-19 00:01:20 UTC
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Post by John
Have never read a reasonable explanation on why "flexing" is banned.
Probably because there isn't one like so many others.
Here's one:

The rules in F1 are tightly defined and the cars are frequently
scrutineered. If the stewards have to resort to taking measurements in a
wind tunel at 300kmh then things get really complicated...
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)
News
2017-07-19 01:00:18 UTC
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Post by ~misfit~
Post by John
Have never read a reasonable explanation on why "flexing" is banned.
Probably because there isn't one like so many others.
The rules in F1 are tightly defined and the cars are frequently
scrutineered. If the stewards have to resort to taking measurements in a
wind tunel at 300kmh then things get really complicated...
They'd learn more about 'flexing aero' on a six DoF shaker rig.
Bobster
2017-07-19 03:05:21 UTC
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Post by John
Have never read a reasonable explanation on why "flexing" is banned. Probably because there isn't one like so many others.
Parts that generate downforce are supposed to be RIGIDLY fixed to the unsprung part of the car.

This goes back to the late 60s, when flimsy wings were mounted high above the car on skinny struts attached to the suspension - and frequently broke.

Even now there is regulations 3.8
Aerodynamic influence
With the exception of the ducts described in Article 11.4, any specific part of the car influencing its aerodynamic performance:
a) Must comply with the rules relating to bodywork.
b) Must be rigidly secured to the entirely sprung part of the car (rigidly secured means not having any degree of freedom).

It's a relic, in a way, and any engineer can quibble with the word "rigid". Is the roof of your car "rigid"? It is? What if place this 20 ton weight on top of it?

So they now have the tests where the wing must not deflect if stipulated loads are applied at stipulated locations.
Edmund
2017-07-19 09:59:11 UTC
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Post by Bobster
Post by John
Have never read a reasonable explanation on why "flexing" is banned. Probably because there isn't one like so many others.
Parts that generate downforce are supposed to be RIGIDLY fixed to the unsprung part of the car.
This goes back to the late 60s, when flimsy wings were mounted high above the car on skinny struts attached to the suspension - and frequently broke.
Even now there is regulations 3.8
Aerodynamic influence
a) Must comply with the rules relating to bodywork.
b) Must be rigidly secured to the entirely sprung part of the car (rigidly secured means not having any degree of freedom).
It's a relic, in a way, and any engineer can quibble with the word "rigid". Is the roof of your car "rigid"? It is? What if place this 20 ton weight on top of it?
So they now have the tests where the wing must not deflect if stipulated loads are applied at stipulated locations.
Which is BS, any load will cause SOME flexing/deformation.

Edmund
Bobster
2017-07-19 10:30:23 UTC
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Post by Edmund
Post by Bobster
Post by John
Have never read a reasonable explanation on why "flexing" is banned. Probably because there isn't one like so many others.
Parts that generate downforce are supposed to be RIGIDLY fixed to the unsprung part of the car.
This goes back to the late 60s, when flimsy wings were mounted high above the car on skinny struts attached to the suspension - and frequently broke.
Even now there is regulations 3.8
Aerodynamic influence
a) Must comply with the rules relating to bodywork.
b) Must be rigidly secured to the entirely sprung part of the car (rigidly secured means not having any degree of freedom).
It's a relic, in a way, and any engineer can quibble with the word "rigid". Is the roof of your car "rigid"? It is? What if place this 20 ton weight on top of it?
So they now have the tests where the wing must not deflect if stipulated loads are applied at stipulated locations.
Which is BS, any load will cause SOME flexing/deformation.
Well, what they do is apply a specified load straight down at specified points. There must be no movement (OK... it may move the width of a molecule or so, but you know what I mean).

So it must not move at specific points under a specific load. Of course it will ultimately start flexing if you apply enough of a load.
Edmund
2017-07-19 11:10:39 UTC
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Post by Bobster
Post by Edmund
Post by Bobster
Post by John
Have never read a reasonable explanation on why "flexing" is banned. Probably because there isn't one like so many others.
Parts that generate downforce are supposed to be RIGIDLY fixed to the unsprung part of the car.
This goes back to the late 60s, when flimsy wings were mounted high above the car on skinny struts attached to the suspension - and frequently broke.
Even now there is regulations 3.8
Aerodynamic influence
a) Must comply with the rules relating to bodywork.
b) Must be rigidly secured to the entirely sprung part of the car (rigidly secured means not having any degree of freedom).
It's a relic, in a way, and any engineer can quibble with the word "rigid". Is the roof of your car "rigid"? It is? What if place this 20 ton weight on top of it?
So they now have the tests where the wing must not deflect if stipulated loads are applied at stipulated locations.
Which is BS, any load will cause SOME flexing/deformation.
Well, what they do is apply a specified load straight down at specified points. There must be no movement (OK... it may move the width of a molecule or so, but you know what I mean).
So it must not move at specific points under a specific load. Of course it will ultimately start flexing if you apply enough of a load.
I know what you mean but it is remarkable that in such a a technical environment
as F1 there seems to be rules that are so very poorly, or not at all defined.
And for a possible safety point of view, rigid materials which hardly bent
will easily break on the first impact.

Edmund
larkim
2017-07-19 11:22:39 UTC
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Post by Edmund
Post by Bobster
Post by Edmund
Post by Bobster
Post by John
Have never read a reasonable explanation on why "flexing" is banned. Probably because there isn't one like so many others.
Parts that generate downforce are supposed to be RIGIDLY fixed to the unsprung part of the car.
This goes back to the late 60s, when flimsy wings were mounted high above the car on skinny struts attached to the suspension - and frequently broke.
Even now there is regulations 3.8
Aerodynamic influence
a) Must comply with the rules relating to bodywork.
b) Must be rigidly secured to the entirely sprung part of the car (rigidly secured means not having any degree of freedom).
It's a relic, in a way, and any engineer can quibble with the word "rigid". Is the roof of your car "rigid"? It is? What if place this 20 ton weight on top of it?
So they now have the tests where the wing must not deflect if stipulated loads are applied at stipulated locations.
Which is BS, any load will cause SOME flexing/deformation.
Well, what they do is apply a specified load straight down at specified points. There must be no movement (OK... it may move the width of a molecule or so, but you know what I mean).
So it must not move at specific points under a specific load. Of course it will ultimately start flexing if you apply enough of a load.
I know what you mean but it is remarkable that in such a a technical environment
as F1 there seems to be rules that are so very poorly, or not at all defined.
And for a possible safety point of view, rigid materials which hardly bent
will easily break on the first impact.
Edmund
Disagree with that last statement, that depends entirely on the construction
material and methods. A diamond which is rigid does not break easily on
first impact.

ISTR that the restrictions on flexing are just an extension of the
moveable aero to avoid something meeting the technical drawings spec for
being in a certain area (when static) but operating in a completely
different area when under real-world load.
Mark Jackson
2017-07-19 13:36:49 UTC
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Post by Bobster
Post by Edmund
Post by Bobster
So they now have the tests where the wing must not deflect if
stipulated loads are applied at stipulated locations.
Which is BS, any load will cause SOME flexing/deformation.
Well, what they do is apply a specified load straight down at
specified points. There must be no movement (OK... it may move the
width of a molecule or so, but you know what I mean).
So it must not move at specific points under a specific load. Of
course it will ultimately start flexing if you apply enough of a
load.
No part of the regulations requires "no deflection" under a specified
test load.
--
Mark Jackson - http://www.alumni.caltech.edu/~mjackson
I believe I am right. And, if not right, plausible.
- Ignatius Donnelly
Bobster
2017-07-19 15:42:21 UTC
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Post by Mark Jackson
Post by Bobster
Well, what they do is apply a specified load straight down at
specified points. There must be no movement (OK... it may move the
width of a molecule or so, but you know what I mean).
So it must not move at specific points under a specific load. Of
course it will ultimately start flexing if you apply enough of a
load.
No part of the regulations requires "no deflection" under a specified
test load.
I haven't read every page of the regs, but I'm sure you're right. The rules just say "rigidly fixed" (or something along those lines).

FIA have deflection tests that they apply to figure out if aero parts are moveable or not and if they are "rigid". These tests amount to a specified pressure applied at specified points. Under those pressures the part being tested must not deflect.

This is not in the rules, it is the test they use to apply the rules. Rules cannot simply be changed mid-season, but the tests can be.

See this article from 2010 that mentions tests made more rigorous during the season, with more changes still to come in that same season.

http://www.autosport.com/news/report.php/id/86162
Mark Jackson
2017-07-19 17:48:34 UTC
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Post by Bobster
Post by Mark Jackson
Post by Bobster
Well, what they do is apply a specified load straight down at
specified points. There must be no movement (OK... it may move the
width of a molecule or so, but you know what I mean).
So it must not move at specific points under a specific load. Of
course it will ultimately start flexing if you apply enough of a
load.
No part of the regulations requires "no deflection" under a specified
test load.
I haven't read every page of the regs, but I'm sure you're right.
As I recall you've mentioned that before. You might consider either
reading the regs or restraining the impulse to describe what they say
when it hits. Just a thought.
--
Mark Jackson - http://www.alumni.caltech.edu/~mjackson
I believe I am right. And, if not right, plausible.
- Ignatius Donnelly
Bobster
2017-07-19 17:59:00 UTC
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Post by Mark Jackson
Post by Bobster
Post by Mark Jackson
Post by Bobster
Well, what they do is apply a specified load straight down at
specified points. There must be no movement (OK... it may move the
width of a molecule or so, but you know what I mean).
So it must not move at specific points under a specific load. Of
course it will ultimately start flexing if you apply enough of a
load.
No part of the regulations requires "no deflection" under a specified
test load.
I haven't read every page of the regs, but I'm sure you're right.
As I recall you've mentioned that before. You might consider either
reading the regs or restraining the impulse to describe what they say
when it hits. Just a thought.
I don't believe I said that the tests are stipulated in the regs. I DID say that the regs require rigidity (and quoted from the regs).

They DO have tests. It's been discussed before. The Autosport article I referenced refers to those, and something similar is still in place.

Remember that in the post at this top of the thread I mentioned Symonds - who should know - referring to tests on the wings.
Mark Jackson
2017-07-19 18:18:59 UTC
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Post by Bobster
Post by Mark Jackson
Post by Bobster
Post by Mark Jackson
Post by Bobster
Well, what they do is apply a specified load straight down at
specified points. There must be no movement (OK... it may move the
width of a molecule or so, but you know what I mean).
So it must not move at specific points under a specific load. Of
course it will ultimately start flexing if you apply enough of a
load.
No part of the regulations requires "no deflection" under a specified
test load.
I haven't read every page of the regs, but I'm sure you're right.
As I recall you've mentioned that before. You might consider either
reading the regs or restraining the impulse to describe what they say
when it hits. Just a thought.
I don't believe I said that the tests are stipulated in the regs.
No, but your description of the specifically required tests (see quote
containing "There must be no movement..." above) was wrong - and from an
engineering or physics point of view, obviously so.
Post by Bobster
I DID say that the regs require rigidity (and quoted from the regs).
But not the part of the regs that would have contradicted the tests you
were misdescribing. I assume you couldn't be bothered to read that page.

In the interest of time I try to keep out of back-and-forth here, so I'm
done with this.
--
Mark Jackson - http://www.alumni.caltech.edu/~mjackson
I believe I am right. And, if not right, plausible.
- Ignatius Donnelly
Bobster
2017-07-19 18:45:19 UTC
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Post by Mark Jackson
Post by Bobster
Post by Mark Jackson
Post by Bobster
Post by Mark Jackson
Post by Bobster
Well, what they do is apply a specified load straight down at
specified points. There must be no movement (OK... it may move the
width of a molecule or so, but you know what I mean).
So it must not move at specific points under a specific load. Of
course it will ultimately start flexing if you apply enough of a
load.
No part of the regulations requires "no deflection" under a specified
test load.
I haven't read every page of the regs, but I'm sure you're right.
As I recall you've mentioned that before. You might consider either
reading the regs or restraining the impulse to describe what they say
when it hits. Just a thought.
I don't believe I said that the tests are stipulated in the regs.
No, but your description of the specifically required tests (see quote
containing "There must be no movement..." above) was wrong - and from an
engineering or physics point of view, obviously so.
I'm no engineer, but anything will flex eventually if you apply enough load - or by an imperceptible amount under a lesser load. This is why FIA have to have tests - being "rigid" is not a binary thing.
Post by Mark Jackson
Post by Bobster
I DID say that the regs require rigidity (and quoted from the regs).
But not the part of the regs that would have contradicted the tests you
were misdescribing. I assume you couldn't be bothered to read that page.
Can you quote it?
Post by Mark Jackson
In the interest of time I try to keep out of back-and-forth here, so I'm
done with this.
Bigbird
2017-07-19 20:02:51 UTC
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Post by Bobster
Post by Bobster
Post by Mark Jackson
No part of the regulations requires "no deflection" under a
specified >> test load.
Post by Bobster
I haven't read every page of the regs, but I'm sure you're right.
As I recall you've mentioned that before. You might consider
either reading the regs or restraining the impulse to describe what
they say when it hits. Just a thought.
I don't believe I said that the tests are stipulated in the regs.
Yet they are.
Post by Bobster
I
DID say that the regs require rigidity (and quoted from the regs).
Yet they don't...

...and you didn't quote from a relevant section. It is almost as if you
were being deliberately misleading.

"Bodywork may deflect no more than" is the common phrase you will find
when you get around to actually perusing the relevant section of the
regs you frequently mention...

...just below the, not so relevant, section you chose to quote from.

HTH
Bigbird
2017-07-19 06:16:38 UTC
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Post by John
Have never read a reasonable explanation on why "flexing" is
banned. Probably because there isn't one like so many others.
I am sure someone will find a decent article for you but my
understanding there are 2 reasons:

1) it permits a form of active aero which is not permitted because it
can lead to very sudden changes in grip. (Consider a flexi floor and
ground effect)

2) perhaps it is assumed flexible wings are more likely to fail

In either case high speed aero failures lead to huge accidents.
D Munz
2017-07-19 12:39:46 UTC
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On Wednesday, July 19, 2017 at 1:20:37 AM UTC-5, Bigbird wrote:

<SNIP>
Post by Bigbird
In either case high speed aero failures lead to huge accidents.
Didn't Villeneuve have a massive moment in Canada when his rear wing flexed right off? As I recall, they were playing fast a loose with the struts to allow the rear wing to flex back (become less resistant) at speed. This lead to a whole new set of tests.

The real problem with the F1 rules in general is that they try to cover too many specifics and always leave room for interpretations. What exactly is the problem with movable aerodynamics? Oh, it's expensive...

We really need to go back to the "fits in a box, has a survival cell for the driver and runs petrol" model. I know there is all this stuff about costs but it is F1. It should not be cheep. (But it must be as safe as possible.)

FWIW
DLM
John
2017-07-20 20:56:02 UTC
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Post by Bigbird
Post by John
Have never read a reasonable explanation on why "flexing" is
banned. Probably because there isn't one like so many others.
I am sure someone will find a decent article for you but my
1) it permits a form of active aero which is not permitted because it
can lead to very sudden changes in grip. (Consider a flexi floor and
ground effect)
2) perhaps it is assumed flexible wings are more likely to fail
In either case high speed aero failures lead to huge accidents.
Being banned as "movable aero" just feeds it to the whole ban on movable aero which has no ligit reason.

Modern materials can flex. Actually the rigidity of materials used likely makes them MORE fragile and likely to splinter.
~misfit~
2017-07-21 02:35:17 UTC
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Post by John
Post by Bigbird
Post by John
Have never read a reasonable explanation on why "flexing" is
banned. Probably because there isn't one like so many others.
I am sure someone will find a decent article for you but my
1) it permits a form of active aero which is not permitted because it
can lead to very sudden changes in grip. (Consider a flexi floor and
ground effect)
2) perhaps it is assumed flexible wings are more likely to fail
In either case high speed aero failures lead to huge accidents.
Being banned as "movable aero" just feeds it to the whole ban on
movable aero which has no ligit reason.
As with the ban on traction control?
Post by John
Modern materials can flex. Actually the rigidity of materials used
likely makes them MORE fragile and likely to splinter.
You're aware of composite materials yes?
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)
t***@gmail.com
2017-07-21 05:12:20 UTC
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Post by ~misfit~
You're aware of composite materials yes?
You fucking grumpy bitch. Fuck off.
Bobster
2017-07-21 03:14:26 UTC
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Post by John
Post by Bigbird
Post by John
Have never read a reasonable explanation on why "flexing" is
banned. Probably because there isn't one like so many others.
I am sure someone will find a decent article for you but my
1) it permits a form of active aero which is not permitted because it
can lead to very sudden changes in grip. (Consider a flexi floor and
ground effect)
2) perhaps it is assumed flexible wings are more likely to fail
In either case high speed aero failures lead to huge accidents.
Being banned as "movable aero" just feeds it to the whole ban on movable aero which has no ligit reason.
Of course it doesn't. Lots of things banned or required in F1 are not banned for any reason bar cost, safety and performance.

The reason that cars now have flat bottoms with a plank on them is first to rule out ground effects and then to prevent ultra low ride heights? And why do they want to prevent those things? Cornering speeds and safety?
Post by John
Modern materials can flex. Actually the rigidity of materials used likely makes them MORE fragile and likely to splinter.
Yes. But again look at history. In the 80s there were several cars that were compliant with the regulations when they could be measured - IE when stationary in the pits - but illegal at race speeds. So how do you get around such issues?

All aero parts on all cars would be absolutely legal when the car was standing still. And it is possible to design those parts such that they flex under load in such a way that improves performance. So you apply tests that say you can have this much flexion under this load or no flexion under this load.
Alan Baker
2017-07-21 06:59:16 UTC
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Post by Bobster
Post by John
Post by Bigbird
Post by John
Have never read a reasonable explanation on why "flexing" is
banned. Probably because there isn't one like so many others.
I am sure someone will find a decent article for you but my
1) it permits a form of active aero which is not permitted because it
can lead to very sudden changes in grip. (Consider a flexi floor and
ground effect)
2) perhaps it is assumed flexible wings are more likely to fail
In either case high speed aero failures lead to huge accidents.
Being banned as "movable aero" just feeds it to the whole ban on movable aero which has no ligit reason.
Of course it doesn't. Lots of things banned or required in F1 are not banned for any reason bar cost, safety and performance.
The reason that cars now have flat bottoms with a plank on them is first to rule out ground effects and then to prevent ultra low ride heights? And why do they want to prevent those things? Cornering speeds and safety?
Post by John
Modern materials can flex. Actually the rigidity of materials used likely makes them MORE fragile and likely to splinter.
Yes. But again look at history. In the 80s there were several cars that were compliant with the regulations when they could be measured - IE when stationary in the pits - but illegal at race speeds. So how do you get around such issues?
All aero parts on all cars would be absolutely legal when the car was standing still. And it is possible to design those parts such that they flex under load in such a way that improves performance. So you apply tests that say you can have this much flexion under this load or no flexion under this load.
I'm going to say this once:

You CANNOT have "no flexion under this load".
larkim
2017-07-22 19:45:32 UTC
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But the FIA never say "no flexion".

Eg in 2015 they said the load test requirements were:-
"A 60N point load will be applied to any part of the trailing edge of any front wing flap, the load will be applied normal to the flap at the relevant point.

"Under the load, the deflection may not exceed 3mm when measured vertically at the trailing edge."
Bobster
2017-07-23 02:36:53 UTC
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Post by larkim
But the FIA never say "no flexion".
Eg in 2015 they said the load test requirements were:-
"A 60N point load will be applied to any part of the trailing edge of any front wing flap, the load will be applied normal to the flap at the relevant point.
"Under the load, the deflection may not exceed 3mm when measured vertically at the trailing edge."
OK... Here's an innocent question asked out of curiosity: Why do they specify things that way? Instead of 3mm movement at a certain load, why do they not specify a lower load and say "no movement"?

Is it because it can be demonstrated that there is SOME movement, even if a very, very small amount?
News
2017-07-23 02:44:45 UTC
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Post by Bobster
Post by larkim
But the FIA never say "no flexion".
Eg in 2015 they said the load test requirements were:-
"A 60N point load will be applied to any part of the trailing edge of any front wing flap, the load will be applied normal to the flap at the relevant point.
"Under the load, the deflection may not exceed 3mm when measured vertically at the trailing edge."
OK... Here's an innocent question asked out of curiosity: Why do they specify things that way? Instead of 3mm movement at a certain load, why do they not specify a lower load and say "no movement"?
Is it because it can be demonstrated that there is SOME movement, even if a very, very small amount?
What are loading and deflection when cornering and hacking across
alligator teeth?

Since that seems to the ultra-slow-motion shot that best illustrates
'flexing aero'...
Bobster
2017-07-23 03:14:50 UTC
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Post by Bobster
Post by larkim
But the FIA never say "no flexion".
Eg in 2015 they said the load test requirements were:-
"A 60N point load will be applied to any part of the trailing edge of any front wing flap, the load will be applied normal to the flap at the relevant point.
"Under the load, the deflection may not exceed 3mm when measured vertically at the trailing edge."
OK... Here's an innocent question asked out of curiosity: Why do they specify things that way? Instead of 3mm movement at a certain load, why do they not specify a lower load and say "no movement"?
Is it because it can be demonstrated that there is SOME movement, even if a very, very small amount?
Or because the engineers can build that stuff that moves not at all under a light load, but flexes like crazy under one more Newton?
Alan Baker
2017-07-23 03:26:35 UTC
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Post by Bobster
Post by Bobster
Post by larkim
But the FIA never say "no flexion".
Eg in 2015 they said the load test requirements were:-
"A 60N point load will be applied to any part of the trailing edge of any front wing flap, the load will be applied normal to the flap at the relevant point.
"Under the load, the deflection may not exceed 3mm when measured vertically at the trailing edge."
OK... Here's an innocent question asked out of curiosity: Why do they specify things that way? Instead of 3mm movement at a certain load, why do they not specify a lower load and say "no movement"?
Is it because it can be demonstrated that there is SOME movement, even if a very, very small amount?
Or because the engineers can build that stuff that moves not at all under a light load, but flexes like crazy under one more Newton?
Read closely:

If you put a load on something it deflects.

There is no way to design something that "moves not at all" under ANY
load. For extremely stiff structures, the movement maybe difficult to
impossible to measure, but it is there.

Can you PLEASE drop this now?
Bobster
2017-07-23 03:49:41 UTC
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Post by Alan Baker
Post by Bobster
Post by Bobster
Post by larkim
But the FIA never say "no flexion".
Eg in 2015 they said the load test requirements were:-
"A 60N point load will be applied to any part of the trailing edge of any front wing flap, the load will be applied normal to the flap at the relevant point.
"Under the load, the deflection may not exceed 3mm when measured vertically at the trailing edge."
OK... Here's an innocent question asked out of curiosity: Why do they specify things that way? Instead of 3mm movement at a certain load, why do they not specify a lower load and say "no movement"?
Is it because it can be demonstrated that there is SOME movement, even if a very, very small amount?
Or because the engineers can build that stuff that moves not at all under a light load, but flexes like crazy under one more Newton?
If you put a load on something it deflects.
There is no way to design something that "moves not at all" under ANY
load. For extremely stiff structures, the movement maybe difficult to
impossible to measure, but it is there.
Can you PLEASE drop this now?
I'm not arguing, I'm trying to understand.

There's a recurring problem with this group that folks are too happy to tell you you don't know or that you're wrong, but are less keen to provide an enlightening explanation.
Alan Baker
2017-07-23 04:27:39 UTC
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Post by Bobster
Post by Alan Baker
Post by Bobster
Post by Bobster
Post by larkim
But the FIA never say "no flexion".
Eg in 2015 they said the load test requirements were:-
"A 60N point load will be applied to any part of the trailing edge of any front wing flap, the load will be applied normal to the flap at the relevant point.
"Under the load, the deflection may not exceed 3mm when measured vertically at the trailing edge."
OK... Here's an innocent question asked out of curiosity: Why do they specify things that way? Instead of 3mm movement at a certain load, why do they not specify a lower load and say "no movement"?
Is it because it can be demonstrated that there is SOME movement, even if a very, very small amount?
Or because the engineers can build that stuff that moves not at all under a light load, but flexes like crazy under one more Newton?
If you put a load on something it deflects.
There is no way to design something that "moves not at all" under ANY
load. For extremely stiff structures, the movement maybe difficult to
impossible to measure, but it is there.
Can you PLEASE drop this now?
I'm not arguing, I'm trying to understand.
I didn't say you were arguing, but this has been pointed out before and
you keep behaving as if you hadn't read it.
Post by Bobster
There's a recurring problem with this group that folks are too happy to tell you you don't know or that you're wrong, but are less keen to provide an enlightening explanation.
Everything flexes; EVERYTHING.

If I set a feather on my engine block, the engine block deflects; not
enough to measure with any technology we have, but it still does.

The FIA chooses loads that make measuring a realistic problem without
having to resort to exotic measuring techniques, and yet not so large
that they risk damaging the structure they're measuring.

A 60N (Newton) force is about equal to 13.5 lbs for instance.
Bobster
2017-07-23 08:04:27 UTC
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Post by Alan Baker
Post by Bobster
Post by Alan Baker
If you put a load on something it deflects.
There is no way to design something that "moves not at all" under ANY
load. For extremely stiff structures, the movement maybe difficult to
impossible to measure, but it is there.
Can you PLEASE drop this now?
I'm not arguing, I'm trying to understand.
I didn't say you were arguing, but this has been pointed out before and
you keep behaving as if you hadn't read it.
Here's a paragraph from the post of mine that you replied to

"All aero parts on all cars would be absolutely legal when the car was standing still. And it is possible to design those parts such that they flex under load in such a way that improves performance. So you apply tests that say you can have this much flexion under this load or no flexion under this load. "
Note "you can have this much flexion under this load". Yes, I know what the rest of the sentence says, but maybe, just maybe, I'm not actually behaving like I haven't read it.
Post by Alan Baker
Post by Bobster
There's a recurring problem with this group that folks are too happy to tell you you don't know or that you're wrong, but are less keen to provide an enlightening explanation.
Everything flexes; EVERYTHING.
If I set a feather on my engine block, the engine block deflects; not
enough to measure with any technology we have, but it still does.
The FIA chooses loads that make measuring a realistic problem without
having to resort to exotic measuring techniques, and yet not so large
that they risk damaging the structure they're measuring.
A 60N (Newton) force is about equal to 13.5 lbs for instance.
Thanks

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