Lotus E21 Renault

[stefan_]

Little plastic and glue and step made up.
Another discussion of 'some' showcar

Yes, but why?

Why would they design and build a nose that is so obviously different to the one they have been using for the last year+ and would only fit this years vanity plate regulations and put it on a promotional video?

For the same reason they have built a nose with a step and several other components for the R31 to be presented as the E20. For a promotional clip/material I presume you want the car to resemble the current one as much as possible and that's why they did it. I don't think Lotus is the kind of team who would try "new" bits on old car during a low-speed-running promotional filming day as this, apart from being silly, would lead to some unrealistic results and a wrong evaluation of the "tested" component.

If Allison decides that a nose with vanity pannel is worth the change, I am sure that it is already tested or testing in the factory right now through CFD and wind tunnel and a run in a practice session before a Grand Prix would be sufficient to asess the benefits or drawbacks of having this solution.

[Rikhart]

So it seems like they copied my bargeboard solution. That gives a bit of a morale boost lol

What do you mean "your solution"? You thought of it before? If so, could you explain what´s the point of this shape?

[N12ck]

So it seems like they copied my bargeboard solution. That gives a bit of a morale boost lol

'your' solution? really?

[wesley123]

So it seems like they copied my bargeboard solution. That gives a bit of a morale boost lol

'your' solution? really?

http://www7.pic-upload.de/03.03.13/ivvo2hly19s.jpg
http://img98.imageshack.us/img98/5395/b ... n2ayi8.jpg

I guess you did not see that the Lotus barge board is split up in 4 pieces, compared to the regular 1 panel.

I posted that on the 25th of september last year in my topic (http://www.f1technical.net/forum/viewto ... 98#p377898)

And I made a quick pic to show it up close. As you can see it is a split up bargeboard, in this case of 2 profiles compared to Lotus' 4 piece.


So yeah, I did think of that solution before Lotus did. My idea was that the vortices shed by the tip of the additional profiles would be benificial in that area, as well as bleeding air from the front side of the sidepod to the back side to help guide the air around the sidepod in a more efficient way. I dont have any CFD, but that was my thought behind it.

[eyalynf1]

So it seems like they copied my bargeboard solution. That gives a bit of a morale boost lol

'your' solution? really?

http://www7.pic-upload.de/03.03.13/ivvo2hly19s.jpg
http://img98.imageshack.us/img98/5395/b ... n2ayi8.jpg

This idea occurred to me as well a few weeks before Lotus put it on their car. I've been trying to work up a solution for my Khamsin Challenge car. I was less interested in shedding vortices, however...

I think you all are missing another effect of the vertical slots in the bargeboards. The static pressure that results from the incidence of the turbulent wheel wake on the face of the boards is converted to velocity pressure in streams of air flowing through the boards. This may produce high quality laminar flow jets along the back of the boards. This flow may also induce higher quality flow in the air between the back/inside of the boards, the keel and the front of the sidepods.

[N12ck]

I didnt see it was split, i thought you were just talking about the steps

[wesley123]

I didnt see it was split, i thought you were just talking about the steps

Ah yes, not a problem

[R_Redding]

Also a multi element barge board is probably used to prevent the separation that can occur when air passing around the aerofoil section breaks up,as when a large barge board (or wing) with a very high wing angle of attack or highly curved section is used.

Very similar to the change to multi element front wing for exactly the same reasons.

Rob

[kwanchepan]

I didnt see it was split, i thought you were just talking about the steps

[eyalynf1]

I didnt see it was split, i thought you were just talking about the steps

http://i.imgur.com/PZA4h4D.jpg
http://i.imgur.com/uJP8jkh.jpg

Awesome pics. I previously thought the bargeboard cascades were joined at the top!

[shelly]

Also a multi element barge board is probably used to prevent the separation that can occur when air passing around the aerofoil section breaks up,as when a large barge board (or wing) with a very high wing angle of attack or highly curved section is used.

Very similar to the change to multi element front wing for exactly the same reasons.

Rob

I would add another two reasons:
- to have a wider range of angle of attack (yaw of the car) of correct functioning
- to have a better behaviour of the vortex detaching from the upper edge of the bargeboard. This is the main aim in my opinion. Wesley123 hinted before at vortex shedding: the interaction of multiple elements give a better vortex. This vortex is energised by multiple steps of acceleration (every slot adds some "turning energy") instead of just one (first leading edge acceleration) and so it is more coeherent, with a slower expansion ratio.
It is the same mechanism employed in the multisection tips of front wings, where the two reasons of high aoa and vortex shedding are present.
Lotus are trying to do something with this vortex, and they need for it to last longer along the back of the car (issue user henra nad I briefly discussed last week in another thread). So next question is: where does this vortex go and what is it used for?

I expect other teams to quickly copy this, starting for ferrari maybe, which seem to use the multisurface approach wherever possible (see 7element fw, rw endplates, slots before rear wheels on the floor, double gurney on top diffuser edge, slotted-two elements pod wing, small slots on upper plate of rear brake duct).
Now that I think of it, after writing this list, i think that the f138 is the most "slotted" car at the moment. Kudos to their production dept.

[zonk]

I expect other teams to quickly copy this, starting for ferrari maybe, which seem to use the multisurface approach wherever possible (see 7element fw, rw endplates, slots before rear wheels on the floor, double gurney on top diffuser edge, slotted-two elements pod wing, small slots on upper plate of rear brake duct).
Now that I think of it, after writing this list, i think that the f138 is the most "slotted" car at the moment. Kudos to their production dept.

thats F2012

[kilcoo316]

I would add another two reasons:
- to have a wider range of angle of attack (yaw of the car) of correct functioning

+1 to that.


The behaviour will be much more consistent in yaw and as you allude to, when cornering, considering the "outside" of the car in the cornering - the combined vortex given off the bargeboard tips will remain coherent for longer around the outside of the sidepod, helping to seal the floor and entrain further flow back in along the top of the diffuser deck.


Of course, you are sacrificing a little in terms of increased lateral load on the bargeboard (and not good lateral load either) due to the multiple elements. Swings and roundabouts - they are obviously seeing more from the improved performance of the floor/diffuser than the little drawback of increased load on the bargeboard.

[kilcoo316]

So next question is: where does this vortex go and what is it used for?

If it follows the decreasing height of the barge-boards, it is a single coherent vortex helping to seal the floor.

If it doesn't, its a vortex sheet ensuring good attached flow around the outside of the sidepod.


Without data to look at, I'd think we're left at guessing which one.

[shelly]

Having some data would be nice - but to me the fact per se that the shape of the bargeboard is as it is, and considering the downwash in front of the floor leading edge, I am reasonably confident that the vortex follow the edge of the bargeboard down and then flows around the sidepod, more or less in the undercut zone. That leads to a countercheck on sauber c32 bargeboard shape