The Technical Questions Thread

[RacingManiac]

I think there are cars that have them as options, I think Porsche GT3 or something you can do that...

I think the potential stability issue with the chemistry might still be a deter people from adopting it, and it is is more expensive...

They are getting very prevalent in FSAE cars....

[RacingManiac]

On the HANS thing above, to my understanding they are useful in racing because the way you are strapped in the car, your body is basically tightly kept in place by the harness and your head is free to move, thus you are getting a much more exaggerated version of whiplash kind of effect in an accident. In more car's inertia reel seatbelt or some of the newer active-restraint, the deceleration your head/neck experienced has been damped by some of the initial movement(and in worse cases, airbag).

[NSXType-R]

I think there are cars that have them as options, I think Porsche GT3 or something you can do that...

I think the potential stability issue with the chemistry might still be a deter people from adopting it, and it is is more expensive...

They are getting very prevalent in FSAE cars....

Thanks for the answer.

[drakkie]

Thanks for the answer.

From my education I remember it had something to do with the load/discharge characteristics as well. Also the cell voltage of Li-ion is 3.7 Volts. Lead battery is 2 V, thus requiring more complicated circuitry to combine the cells to a constant 12 Volts for your vehicle. The leadcell is also better able to cope with peak currents (starter motor for example).

(edit: damn I should have paid more attention in school)

[Matra et Alpine]

yep, direct experience of Li-ion on the race cars is they are fine as long as not having to start too often or an especially tight engine. Most now have Lead-acid battery on a sled with plug for starting and leave the Li-ion for energising and quick restart if necessary.

[Magnum9987]

Most of the hybrid motorcycles that have been popping up in small numbers lately have been added to the rest of the drivetrain, as in they drive the rear wheel. Would their be any performance benefit to instead drive the front wheel instead? I would think it would come in handy giving more grip during acceleration and allowing the rider to get on the throttle sooner coming out of a slow or even high speed corner. As well, wouldn't it aid braking force as riders use the front wheel to brake more than the rear, and can thus recover more electric energy if used as a motor/generator?

[Matra et Alpine]

driving the wheel for steering is bad, just look at cars ! Bikes worse.
CRITICAL that a bike front wheel has minimal mass otherwise it is a huge gyroscope and will NOT steer
You get LESS grip in acceleration from anything that drives the front wheels due to weight transfer - google it to learn more.
Energy recovery is true, but you can get quite a lot in normal road use from rear as seldom would an ordinary rider brake so hard to regularly lift the rear wheel. ALSO, recovering from rear is similar feel to engine braking and the rider is used to that.

[RacingManiac]

Well 2WD bike have won Dakar before...EV based FWD on the bike might be lighter than the hydraulically driven front like those....

[Matra et Alpine]

good point RM, horses for courses. An off road bike has different criteria, speeds and conditions and so giving up some steering responsiveness at speed for another driven wheel in sand is a plus .... just then reliability

[NSXType-R]

Not really a technical question, more of a racing logistics question.

For open race cars like the Audi R8 that ran in Le Mans a couple years back, what sort of racing suit do they wear? Normal nomex ones? I was watching Truth in 24 and I was thinking, man, it must suck if it rained. I mean, I'm pretty miserable if I have to spend a couple hours with wet shoes and socks. I can't imagine racing a full stint in pouring rain.

[RacingManiac]

I've driven FSAE cars with full nomex suit in the wet, pretty terrible by the end of it....its unavoidable...

In cases like those big races with big teams, I am sure they have dryer or even clean suits to switch into between stints...Though actually at the speed they are going you might be a bit less wet than we are in FSAE cars since the monocoque does isolate a bit better than our tube frame cars does, and the aero are designed to divert airflow away from the cockpit opening for better efficiency...

Interesting too that most drivers that I've heard in the interviews preferred the open car since they don't get a foggy/dirty windscreen...

[drakkie]

In a long race I don't think there is much difference in the end whether it's dry or raining. You are soaked anyway, be it of sweat or rain.

[henk4]

In a long race I don't think there is much difference in the end whether it's dry or raining. You are soaked anyway, be it of sweat or rain.

longest stint for a driver these days is 3x45 minutes, (rarely 4) after which he will probably do the next stint in a dry overall.

[NSXType-R]

I've driven FSAE cars with full nomex suit in the wet, pretty terrible by the end of it....its unavoidable...

In cases like those big races with big teams, I am sure they have dryer or even clean suits to switch into between stints...Though actually at the speed they are going you might be a bit less wet than we are in FSAE cars since the monocoque does isolate a bit better than our tube frame cars does, and the aero are designed to divert airflow away from the cockpit opening for better efficiency...

Interesting too that most drivers that I've heard in the interviews preferred the open car since they don't get a foggy/dirty windscreen...

I was watching Truth in 24 Pt 2 and Tom Kristensen talked about how he preferred closed racers in terms of buffeting and comfort. I guess you are right though, you can change a helmet faster than you can wipe down a windshield.

The buffeting has got to be an issue to some extent though.

In a long race I don't think there is much difference in the end whether it's dry or raining. You are soaked anyway, be it of sweat or rain.

True you're drenched in sweat, but that's not something you can avoid (much). If it's a closed car, that little bit may help with driver morale and fatigue.

Every bit counts.

[RacingManiac]

Again, aero does a lot to mitigate the buffeting issue.