Aero elastic design energy consumption vs drag Trade off

[DaveW]

Less than 40 turns in the entire year are taken at over 220kph and a lot of it is only possible during qualifying.

I think you may have forgotten the infamous Turn 8 at Turkey which, a couple of years ago, Vettel took in a gear higher than anybody else & prompted LH to declare the RBR "has twice our D/F". The advantage gained at that corner alone gave Vettel pole position.

The issue here is lateral balance, I think. There is no point in improving rear D/F with trick floors & exhausts if it simply causes the car to understeer off.

[turbof1]

The issue here is lateral balance, I think. There is no point in improving rear D/F with trick floors & exhausts if it simply causes the car to understeer off.

Yes there is. You are correct to say the balance has to be good; generally speaking, and assuming the centre of gravity is always given, that means that the part of the car with the lowest D/F dictates the downforce of the other parts. That part in the current generation of cars, is the rear. Teams can easily increase downforce at the front when they find improvements with trick floor and exhausts, thus getting the aero balance back.

[DaveW]

...Teams can easily increase downforce at the front ....

I agree with your thoughts in general, but I do wonder if "easily" is the appropriate word.
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[turbof1]

Teams already ran higher downforce front wings in 2010 en 2011. It might indeed be a litlle bit more complicated to slap on some elements of those wings though. Current front wings are optimizing into the smallesr details airflow towards the back of the car. Increasing front downforce would probably go hand in hand with a decrease in downforce to the back. So if you find an improvement at the back, it needs to be big enough so that the lost of downforce at the rear, routed by the front, is catched.

We did see something like that near the end of the 2011 season: McLaren updated their front wing at India, if I am correct, removing a few curves in the main plane. That would lead to higher front downforce, but also to a lost of effeciently routing air to the back. Apparently they gained so much rear downforce through the year by developing the EBD, that they could do that.

[DaveW]

.... removing a few curves in the main plane. That would lead to higher front downforce ....

Forgive me, but I find that idea counter-intuitive. If they started with fewer "curves", and then reduced wing incidence to counter the alleged increase in D/F, the result would, presumably, be a reduction in parasitic drag. So why wouldn't they do that?

[turbof1]

The curves were there to create vortices, which help directing airflow all the way to the back of the car. One should not forget that the front wing conditiones a huge part of the airflow over, under and around the car. Hence why teams prefer a lower DF to drag coëfficient at the front, because else this would lead to having less downforce at the back.

But if you as a team suddenly are able find a good amount of improvement at the back of the car, then you want to balance that out again at the front. Each team could do that differently, but it will require to sacrifice some of the quality of the airflow. As long as the benefits outweight the disadvantages, teams are happily to do so.

You might want to check this article out: http://scarbsf1.com/blog1/2012/04/25/mc ... velopment/
I think that explains it at its best.

[DaveW]

I think that explains it at its best.

Thanks for the explanation, I appreciate it.

It certainly explains why L/D is sacrificed to increase airflow under the car, and suggests an improvement in L/D would expected if a "few of the curves were removed", but not necessarily how front D/F can "easily" be increased, although scarbs does hint that this might be the case. I'm sure that its not entirely analogous, but an F1 front wing is rather reminiscent of the wings of a modern transport aircraft in landing configuration - which has (close to) maximum drag, but also maximum lift coefficient, I recall.

Interestingly, I discovered the following Quote: "This effect varies greatly with front wing ride height, so that when the wing flexes down under load at speed, the airflow changes. I have learnt from F1 aerodynamicists that the effect of the endplate on flow around the wheel as the wing flexes down, is perhaps more important than downforce gained [by] the wing being closer to the ground." It is tempting to conclude that D/F will be gained by lowering the front wing, and it might also benefit airflow under the car.

[turbof1]

Interestingly, I discovered the following Quote: "This effect varies greatly with front wing ride height, so that when the wing flexes down under load at speed, the airflow changes. I have learnt from F1 aerodynamicists that the effect of the endplate on flow around the wheel as the wing flexes down, is perhaps more important than downforce gained [by] the wing being closer to the ground." It is tempting to conclude that D/F will be gained by lowering the front wing, and it might also benefit airflow under the car.

A low front wing is always wanted due ground effect. However, there are minimum heights which make that more difficult. More rake could allow a lower ride height as the minimum height is calculated from the reference plane, but also with aero flex.

About the endplates: you might want to check this article out http://mccabism.blogspot.be/2012/07/whe ... ction.html. I know it's more about a pre 2008 front wing, but it does gives some insight

[godlameroso]

It makes sense as aiming the endplate vortex more tangental to the front tires would potentially reduce their shedding vortecies which would have a knock on effect downstream. That said I wonder if we'll see endplates designed to do just that.

[DaveW]

However, there are minimum heights which make that more difficult. More rake could allow a lower ride height as the minimum height is calculated from the reference plane, but also with aero flex.

Also, perhaps, a secondary suspension mounted between the tub proper & the nose box.... one that doesn't come off with the nose box - just a thought....

[gixxer_drew]

I've done that before pushing on a dowel pin. You only need a very tiny displacement there for a big change at the front. Used rubber though. On he car in question that also let the whole car setup be softer and lower as bottoming was an issue.

[gixxer_drew]

Double post removed

[gixxer_drew]

Dangerous stuff, aeroelasticity. - as Massa might confirm, if you recall the incident.

Just reviving this post, based on the way they needed to pass the tests for the flex front wings I thought the easiest way would be tension wires either driven by something like the third spring position.

I calculated a best guess at the eddy frequency of the front wings and it corresponded to the oscillation frequency in the video based on the frame rate, so its a bit vague. However, that video further indicated something loading only in tension as opposed to a solid rod which could support forces in both directions if it were say opposed by a spring. It would have had a different feel. That really had me nearly certain of the tension wire concept.

Then came the video of Alonso's incident with the front wing in Malaysia, the way it shattered but retained those bits I was thinking "YES! nail in the coffin!" Then he proceeded to go right to the camera with the front wing dangling from wires all the way in and the front tires motionless on top of the remaining structure. I guess that settles that one, in my mind at least.

Flexi wings are nothing new, but I am a little disappointed though because I look at the eddy frequencies in terms of porpoising all the time. It can sometimes manifest like that... "BAM BAM BAM" as it was once described by a driver and we would see much lower frequencies for an underwing. Surprised this one slipped by and the resonance happened like that. I expected they were way ahead of me on that one.

[Smokes]

could be something to do with the j-damper settings

[olefud]

The issue here is lateral balance, I think. There is no point in improving rear D/F with trick floors & exhausts if it simply causes the car to understeer off.

I’m having trouble parsing this. Within reason, wouldn’t it make sense to gain rear D/F and decrease front roll stiffness/couple? Of course aero balance would be speed dependent so the weight transfer would need to be rejiggered with speed.