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Would the decoupling account for the absence of axial tire oscillations?DaveW wrote:) to lower the mean running height of the front wing.
Your comments on the effectiveness of the RBR front suspension are well made. It should, perhaps, be observed that they probably have a "decoupled" front suspension, very stiff in "heave", but very soft in "roll", and run a "heave" inerter (which, amongst other things, reduces the effective dynamic spring stiffness).
Not quite sure what you mean, but a suspension set-up as described allows (potentially, at least) the front dampers to do their share in controlling both the sprung mass & hub modes.olefud wrote:Would the decoupling account for the absence of axial tire oscillations?
In other clips –Push Rod Flutter?- the tires show a pronounced axial oscillation when hitting curbs that is not evident in the above clip. It’s probably differing conditions.DaveW wrote:Not quite sure what you mean, but a suspension set-up as described allows (potentially, at least) the front dampers to do their share in controlling both the sprung mass & hub modes.olefud wrote:Would the decoupling account for the absence of axial tire oscillations?
Different car (design), I believe...olefud wrote:In other clips –Push Rod Flutter?- the tires show a pronounced axial oscillation when hitting curbs that is not evident in the above clip. It’s probably differing conditions.
That's the positive way of thinking about the problem. Arguably, life becomes really interesting when the aerodynamic forces affect the structural response, as Ferrari discovered last year.riff_raff wrote:The concept of aeroelasticity is about how structural responses affect aerodynamics.
You are right, of course, but I think that race car aeroelastics is complicated by the fact that aerodynamic forces are often affected massively by the relative position (& rate of change in position) of the ground plane. The whole vehicle instability known as "porpoising" is an example. F1 cars have exhibited the phenomenon (an oscillation occurring at a frequency of around 7 Hz) at higher airspeeds since ground effect was invented. Today, F1 cars are usually stable, but are sometimes observed to porpoise immediately after the brakes are applied at high speed (I recall seeing an interesting video comparing the response of different vehicles at Turkey, I think). Again, I believe that the last generation of Audi LMP vehicles sported a set vortex generators on the underside of the front splitter (wing) - I would not be surprised if they were there to delay the onset of porpoising.riff_raff wrote:Wings on a racecar are no different than wings on an airplane in this regard.
Aeroelastic properties have been used to advantage on several occasions (mostly by missiles - I believe the Bloodhound was an early example). Latterly the X-53 was a research vehicle with "active" aeroelastics. None of them have attempted to use flutter, for a couple of reasons: flutter extracts energy from the air (hence increasing drag), and it is dangerous (structural failure usually follows quickly).godlameroso wrote:But has there ever been any aircraft designed with wings that oscillate, or pivot on an axis like the Red Bull wings?
aren't modern F1 cars encrusted with aero surfaces that only work well at very low Re nos ?DaveW wrote:Your argument is convincing, godlameroso, and your reference is very interesting. The abstract mentions a Reynolds Number of around 2000. Do you think the conclusions would still be valid if the experiment was scaled up by, perhaps, 500?
Well for one thing F1 cars aren't too concerned with air as a compressible medium, but they are, or should be concerned with air's viscosity as it's a value that changes depending on temperature(exhaust gases, ambient, etc.). At over 240kph the cars generate plenty of downforce but there aren't many turns on the F1 calendar that are taken at such speeds. Maybe less than 4 per track visited. By turns I mean an angled corner that requires every ounce of concentration on the driver's part to make it through as quickly as possible, Eau Rouge does not count as a corner whereas Pouhon does. The point being that for an F1 car to be fast relative to it's competition it has to generate the most downforce possible in the area between 80kph and 220kph as the vast majority of corners are taken in this speed range.Tommy Cookers wrote:aren't modern F1 cars encrusted with aero surfaces that only work well at very low Re nos ?DaveW wrote:Your argument is convincing, godlameroso, and your reference is very interesting. The abstract mentions a Reynolds Number of around 2000. Do you think the conclusions would still be valid if the experiment was scaled up by, perhaps, 500?
(no wonder the cars look like creepy-crawly dinosaurs)
don't these work particularly badly at higher Re nos ?
(no wonder the cars dump aero as soon as they can, by DRS and not-DDRS and aeroelastic evasion of the rules)
it's a bit like the grotesque 1920s aerofoils
(that were developed in wind tunnels at hopelessly low Re nos and were thereby rubbish on real aircraft, but good on models)
