Lister LMP Technical Question

[Try Hard]

This ones aimed mainly at AMT and MulsaneMike, but anyone else with good aero knowledge, please chip in:

I was thinking about the Lister LMP last night (pondering ideas for a new lmp car), and a thought struck me.

How does yaw conditions affect the cooling solutions on the Lister?

What I mean is, as the car is turning (so the airflow is no-longer directly ahead, but coming from an angle), surely the amount of airflow in one of the intakes is limited/reduced, leading to hotter rad temps.
Now I understand that the intakes extend ahead of the front fender for this reason, and I notticed a sight curve in the intake's as well, so surely this would only work for one intake when running in a yaw condition?

To simplyfy a little, if the car is turning right, the right hand intake will be getting "good" air, whereas will the left hand one not?
How much of an affect (if any) does this have on the cooling of the car?

I can understand that for a circuit like Le Mans (long, fast straights equaling long periods with decent straight airflow) this probably wouldn't be a problem, but what about on tighter twisty courses? I would hazard a guess that on most circuits (running clockwise, therefore predominantly right hand turns) the left hand radiator would be hotter.

I'm just asking this as i do really like this solution (and the Lister is my fav LMP at the mo), but I was intrigued to know how much of an affect (if any) this would have.
Also I see the '04 car has a F1 style engine airbox (with the intake above the drivers head, a la Pesca Courage Evo.), would this allow the "scoops" to be reduced in size, as they no longer have to serve engine induction as previously?

Any opinions on this?

Regards
Ed
P.s. Mike what programme do you use for your logos?

[MulsanneMike]

Yaw effects on cooling would be minimal if not completely a non-issue. And I don't think it would be worth the effort to reduce the ducts size as the volume of air provided for engine induction is miniscule compared to that provided for cooling. I use AutoCAD 2000.

[Try Hard]

thanks for the response mike, just wanted to clear that up in my head
Regards
Ed

[Fieldgate]

Think time in a corner (I'm equating your yaw response to that).

Bigger issue of airflow, drag & cooling with zero yaw angle (ie in a straight line) for a lot of cars, with lots of opportunity to fine-tune....

[billnchristy]

I think the only time you would worry about that would be on an oval where youre turning more than going straight.

[Dauntless]

Mike is right that yaw influences on cooling are nil. My Atlantic has just one radiator for the engine coolant, situated in the left sidepod, and consistently overcools the engine even though we normally run clockwise. Go figure...

It might be a different issue if the driver were "drifting" the car sideways through each turn, a la a sprint car on dirt, but the actual yaw angle on a road course is so small as to be negligible.

[Tim Northcutt]

For me the cooling issue that I have wondered about involves any ambient heat from the brakes, since those ducts seem to serve a dual purpose of engine cooling and brake cooling vents....

Does that intake design possibly send hotter air than is necessary back into the radiator system???


And could that create overheating issues for the car???

We don't have any empirical data to really go by from races, because the car hasn't turned that many actual race laps since its creation...

I'm interested in thoughts by Mr. Thorby, Mulsanne Mike, Dauntless, or any others on this issue...

Thanks!

[AMT]

Yaw wasn't something I could look at in my wind tunnel tests, but I did think about the effects of steering angle on the flow in the ducts, both to the brakes and the rads, and tried to shape the brake scoops to minimise the adverse effects of lock. Don't know if it worked though!

Sophisticated tunnels allow the model to be yawed, but even then you don't get a true picture of the flow over a car when it's in a corner. That's because the both the front and rear tyres have roughly the same slip angle, but the front tyres also have a steering angle. That means that the front of the car is moving at one angle relative to the airflow, and rear of the car is moving at a different angle! No-one can solve that problem of model testing I think...

[Tim Northcutt]

Thanks for the insight AMT....nobody better to address the issue tnat the persone who created it...

I have a couple of brief follow-up questions:

I have no idea how those ducts are channeled back beyond the opening in front....but they serve as cooling ducts for the brakes as well as the engine, correct?

Would ambient heat from the brakes be a possible issue for the radiator cooling???

Especially if you were on a circuit like Sears Point, or a street course, where the straights aren't long and there is lots of braking???

Just curious

[Try Hard]

Thanks for the response AMT, I take it that is why the "scopes" extend in front of the fenders.
Interesting point you raise about the yaw in tunnels too

This is why i love this forum!

Its also making me more determined to get into motorsport when I graduate, just need to find somewhere looking for a graduate materials engineer....

Ed

[AMT]

The inner front wheelarch of the lister is open, so that the air in the duct blows past the inboard face of the wheel. There's a scoop (like a single-seater) to duct air into the brakes. That scoop feeds off the big duct, but the total air flow in the duct is enough to supply both rads and brakes. We measured the rad pressure drops in the tunnel to ensure we got enough cooling. However, that was only with the wheels straight ahead, and I had to guess the effect of the brake scoop when the wheels were steered.

The scoops stuck forward because a) the regs require no mechanical parts (e.g. front suspension) to be visible from the front of the car - hence the ducts have a "chicane" in them at the front, b) because they grab the best airflow and c) because the long duct gives the best chance of optimal use of the whole rad face area.