Aero elastic design energy consumption vs drag Trade off

[Smokes]

Does anyone know the anything about the trade off between the drag reduction of a aeroelastic part and the energy it comsumes to move the aeroelastic part.
Say in comparision to mechnical adjustable aero part of the same mass and profile.
I was just wondering how much energy is consumed in moving an aero elastic part in a f1 car at a steady state ( I know an f1 car is in constant accelaration) and the drag reduction gained in a steady state.
Would there be any benefit in the progessive change of movement in relation to the mass flow rate driving the change.
Vs using an actuator to mechanically move the part.

If this has already been answered please point me to the correct thread.

Thanks

[olefud]

This may be a bit of an imponderable. If the trade off is between drag and down force, and the aero elastic decreases drag and down force at just the right instant and in the needed ratio, there is no downside. But optimum down force generally isn’t a function of speed so most likely down force will be off in high speed corners or high speed straights since aero elastic can’ distinguish between the two –yaw aside.

It isn't so much energy consumption as useful energy consumption.

[Greg Locock]

If you imagine a wing section mounted on an axis at its aerodynamic centre it requires zero effort to change its angle of attack. Therefore any energy required is set by practical considerations, and with sufficient ingenuity can be reduced to as near zero as you are prepared to approach.

More practically, the servo for a radio controlled aircraft produces at most 10s of watts of mechanical power instantaneously, and is controlling the aerodynamics of something that is generating 100s of watts of drag continuously. So it is always energetically worthwhile to invest in minimising drag.

[Smokes]

But if an aeroelastic part moves it is dependant on the rate of flex? say you set the flex to 1000N/mm it will only flex 1mm at a 1000N of force right. so the part still has to generate a force in order to flex the part right. #so the CD = Q and the angle of attack @ 1000Nm at Q.
I am a mechanical engineer and not to brillant with aerodynamics.
I am thinking what would the graph look like for a naca wing pivoting at the leading edge and a 1000n/m sping a the trailing edge.

[Jersey Tom]

so the part still has to generate a force in order to flex the part right

The force is always there. That's why it's aeroelastic. You have some pressure on the thing from the airstream, and you're just selectively softening some part of the structure to allow it to deflect more under the load you already have.

[flyboy2160]

so the part still has to generate a force in order to flex the part right

The force is always there. That's why it's aeroelastic. You have some pressure on the thing from the airstream, and you're just selectively softening some part of the structure to allow it to deflect more under the load you already have.

there is what is called 'active' aerodynamic shaping - which requires work to move or change the shape of the surface - and the 'passive' free lunch type jersey tom mentions.

he's right about the force being 'free', but i'd nit-picky adjust his statement to 'deflect in a way you prefer.' it looks like the front wing-nose-pylon structure could be tweaked to reduce the AOA under load - that is, have the wing twist as load is applied - to reduce both lift and drag. this ply tweaking to get similar effects in composite aircraft is commonplace today.

[DaveW]

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

[Tommy Cookers]

it looks like the front wing-nose-pylon structure could be tweaked to reduce the AOA under load - that is, have the wing twist as load is applied - to reduce both lift and drag. this ply tweaking to get similar effects in composite aircraft is commonplace today.

isn't the premise of the OP misplaced ?

there are rules that attempt (unsuccessfully) to maintain aero surface stiffness by defined mechanical tests
a car can be legal and achieve (passively) gainful aeroelastic deformation that could not legally be achieved actively
so the argument over the relative efficiency of passive vs active is sterile ?

aeroelastic factors have been the remit of structural etc design since 1918 (shear centre positioning etc), ie 'tailored structures'
with composites we additionally can design the material for aeroelastically gainful non-isotropic properties, ie 'tailored elasticity'
but in aviation this is all to reduce aeroelastic deflections (and their interactions with aerodynamic effects)

now in F1 we use TE to increase aeroelastic deflections
presumably TE could even discriminate eg between a fast corner and a straight to develop suitable DF and drag ?

[Smokes]

Aeroelastic engineering goes back to the Wright brothers wing warping concept?

My only thought though is the part will flex to give a constant max force a variable massflow rate right? Until the part hits it flex limit. Is there a fatigue life limit to the parts that flex in this way?

[DaveW]

Aeroelastic engineering goes back to the Wright brothers wing warping concept?

Don't think so.. not intentionally, anyway. Aeroelastic problems actually preceded the Wright brothers, look inside this book at 1-2 Historical Background here.

[jamsbong]

To answer your question.
More drag = more energy consumption.
there is always more drag at high speed as drag/lift or any other aero induced force increases exponentially. F function of v^2.

If your aero elastic design deforms to a less draggy shape, then it will reduce drag when it is deformed and thus reducing energy consumption.

[DaveW]

To answer your question....

Your implied criticism of my post is quite justified, and I apologize for that.

On the other hand, It is not clear to me why Smokes asked the question. In my view, energy consumed by the motivator would not be the main reason for consciously trying to use aerolasticity to produce an effect.

Usually, I guess, the main reason would be to overcome regulations, where a mechanized solution would not be permitted. An example would be the "DRS" system now being to used (in a restricted way) to reduce the drag of the rear wing when the down force is not required. That idea is at least 20 years old. In F1, many of the high speed crashes after a catastrophic rear wing failure were the result of attempts to achieve the same effect aeroelastically. Again, the infamous Mercedes crashes at Le Mans were similar (except here the suspension was the elastic element). In recent times, the Massa "vibrating" front wing was caused by Ferrari attempting to emulate the RBR "flexi" wing.

The question, and replies to it, all suggested (to me) that the conscious use of aero forces to manipulate the structure of a race car would be a simple "stroll in the park". It is a fact, however, that the idea is both technically challenging & potentially dangerous. Energy consumption would not be high on my list of priorities. That was the reason for my OT response to the question.

[shelly]

+1 to davew for linking the bisplighoff.

[Smokes]

Thanks DaveW.
I know moving air structures are not new, it just like you pointed out aeroelasticaly is dangerous and difficult to control. I also cannot think of any examples of aero/hydro elastical bodys in nature apart from the flying squirrel. I just wanted to know the trade off in energy consumed moving the part and the drag reduction gained in a quantifable form , would be reason why teams are pushing in this direction.

I personally think having mechanical moving aero like the pagani huyrara would be a better and more effective way forward.

[Greg Locock]

I also cannot think of any examples of aero/hydro elastical bodys in nature apart from the flying squirrel. .

A gale blows through a forest. A leaf on a tree is blown into a new position, reducing the drag on the tree. Aerolastic

A jellyfish pulses its umbrella to move forward. It then relaxes, the umbrella collapses, reducing the drag on the jellyfish. Hydrolastic.

If you definition of XXXolastic is that a structure is deformed elastically by an impinging fluid and moves in such a way as to usefully modify the forces it sees, then I think it is actually quite common, bird's feathers being the most common example.