Short wheelbase Vs Long wheelbase 2011

[Formula None]

Longitudinal load transfer can be a good thing, y'know.

JT, would you mind explaining or giving an example?

I assume rallying and drifting rely heavily upon shifting weight forward to make it easier to break the traction of the rear tires. For example the Scandinavian flick involves tapping the brakes or lifting off throttle to transfer weight from the rear tires, helping break their traction.

Edit: Video with some obvious forward weight transfer:

[ringo]

Well those posts are enlightening, but it would be more fortified with diagrams or equations.
It best if things can be quantified or represented rationally.
If it's not too much to ask.

[747heavy]

ringo, you will find most/all of the equations at Gillespie or/and Milliken.

this is perhaps a start.
note, this examples do not account for downforce, as they are for road cars, but they underlying equations/principles should be the same.


http://home.robotic.de/fileadmin/contro ... ker95b.pdf

http://ntl.bts.gov/lib/16000/16500/1653 ... 104164.pdf

http://www.google.de/patents?lr=&vid=US ... ng&f=false

[red300zx99]

Long weight shift helps with forward acceleration.

[ringo]

After doing some reading, I haven't threshed out the basics from the articles yet, it seems that the yaw rate increases with decrease in wheel base.
The yaw rate is related to the agility of the vehicle or responsiveness as well.

Looking at the F1 cars and the fact that a rim radius is the difference in wheel base, how much more agility will a shorter car have and is there a point when so much agility is enough?
Maybe too much agility could mean the steering has less feel as well or maybe a driver's reaction is not enough to detect the difference in agility?

an interesting FSAE paper:
http://www.unece.org/trans/doc/2010/wp29grrf/AMEVSC-03-03e.pdf

Steady State Conclusions
The steady state simulation has uncovered useful information for the design
of future FSAE vehicles. Knowing the relative importance of each of the
variables will aid the designers of the University of Toronto team in improving
overall vehicle performance. A summary of the results of the steady state
analysis is presented in Table 3.1. Center of mass height had the largest
impact on performance at 0.56%. Mass was close behind at 0.48%. Track
had a moderate eect on performance at 0.19%. While the eect due to
wheelbase on steady state cornering is almost negligable at 0.02%. Mass
distribution also has on inuence on steady state cornering.

further on in the paper:

As can be seen from Figure 4.2 increasing wheelbase improves transient
response despite the vehicle suering an increase in yaw inertia. If wheelbase
was increased by 5% the response time would decrease by 2.4%.

though this is more stability related.

[red300zx99]

The mechanical downsides are all stability related, a car with a shorter wheelbase needs less steering angle to navigate a turn then a longer one.

[Tozza Mazza]

I believe the normal wheelbase for a current F1 car to be around the 3300mm mark, meaning the floor is 3320mm long, including the splitter and diffuser. Stepped floors have less low pressure than flat ones, but the longer the floor the more downforce can be generated above it, but it loses handling prowess (F1 drivers tend to like nervous oversteery car, a factor for mercs tiny wheelbase?).
TM

[JohnsonsEvilTwin]

(F1 drivers tend to like nervous oversteery car, a factor for mercs tiny wheelbase?).
TM

An indication of where the teams priorities lie? I'm only being machiavelian...

But it does indicate the team have alot of faith in the Aerodynamics department.

[marcush.]

the Merc is only short by 2011 standards.
Toyotas head of design not long ago stated something like 3300mm was considered a good value for driver comfort in terms of vehicle stability.
the times of ultrashort F 1 cars is long gone in the 70/80s a long car -lotus 78 -had 2700mm wheelbase and a short one had 2386mm..(Tyrrell 005)

[DaveW]

I saw my first 3m w/b F1 vehicle in 2006. Wheelbase appears to have increased steadily since then, on average, but I guess the value might well be track-dependent (more "mechanical" tracks = shorter wheelbase). That was certainly true for Champ cars.

Ross Brawn in 2007: http://www.formula1.com/news/features/2007/5/6134.html

[Sayshina]

(F1 drivers tend to like nervous oversteery car, a factor for mercs tiny wheelbase?).
TM

Actually, traditionally there's been a fairly even split between drivers who prefered "nervous oversteery" cars and those who prefered more stable understeering cars. Prost is probably a classic example of the latter, and of the former look up a video of Villeneuve.

A F1 designer a few years ago (during the barge board era) stated that a longer wheelbase primarily let you present cleaner flow to the sidepods and allowed more surface area to "work the flow". This would seem to indicate that friction drag was not a high priority, and also seems to indicate that modern designers tend to look at every square cm of the car as a potential downforce producer.

Other than the barge boards, I don't really see anything in the regs that would change his comments, and since we know they are in fact still trying all sorts of things to clean up the flow into and around the sidepods I'd say it still applies.

You could look up current trends in Moto GP as well, where weight transfer is possibly the 3rd biggest factor (behind riders and transient engine response) in performance. Sure, it's a different discipline, but most of those differences only showcase what's happening (vastly smaller contact patch, higher c of g, no downforce). The same math applies to formula car handling, it's just not as noticable.


Finally, Maclarens "fiddle brake" clearly demonstrates that agility is still important to a modern F1 car, as it's purpose was in effect to snap the car toward the apex on turnin faster than it's geometry would normally allow.