Short wheelbase Vs Long wheelbase 2011

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Formula None
Formula None
1
Joined: 17 Nov 2010, 05:23

Re: Short wheelbase Vs Long wheelbase 2011

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Caito wrote:
Jersey Tom wrote: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:

[youtube]http://www.youtube.com/watch?v=Vr__FDbCDPI[/youtube]
Last edited by Formula None on 27 Feb 2011, 20:02, edited 1 time in total.

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ringo
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Joined: 29 Mar 2009, 10:57

Re: Short wheelbase Vs Long wheelbase 2011

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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.
For Sure!!

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747heavy
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Joined: 06 Jul 2010, 21:45

Re: Short wheelbase Vs Long wheelbase 2011

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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
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look what they can do to a carburetor in just a few moments of stupidity with a screwdriver."
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red300zx99
red300zx99
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Joined: 19 Feb 2003, 09:02

Re: Short wheelbase Vs Long wheelbase 2011

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Long weight shift helps with forward acceleration.
gridmotorsports.com

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ringo
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Joined: 29 Mar 2009, 10:57

Re: Short wheelbase Vs Long wheelbase 2011

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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/wp2 ... 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.
For Sure!!

red300zx99
red300zx99
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Joined: 19 Feb 2003, 09:02

Re: Short wheelbase Vs Long wheelbase 2011

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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.
gridmotorsports.com

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Tozza Mazza
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Joined: 13 Jan 2011, 12:00
Location: UK

Re: Short wheelbase Vs Long wheelbase 2011

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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

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JohnsonsEvilTwin
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Joined: 29 Jan 2010, 11:51
Location: SU 419113

Re: Short wheelbase Vs Long wheelbase 2011

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Tozza Mazza wrote:(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.
More could have been done.
David Purley

marcush.
marcush.
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Joined: 09 Mar 2004, 16:55

Re: Short wheelbase Vs Long wheelbase 2011

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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
DaveW
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Joined: 14 Apr 2009, 12:27

Re: Short wheelbase Vs Long wheelbase 2011

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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
Sayshina
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Joined: 04 Mar 2011, 21:58

Re: Short wheelbase Vs Long wheelbase 2011

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Tozza Mazza wrote:(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.

OO7
OO7
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Joined: 06 Apr 2010, 17:49

Re: Short wheelbase Vs Long wheelbase 2011

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I used to believe one of the reasons for the increase in wheelbase length was due to the banning of refuelling, however for instance, there is very little difference between the wheelbase of the Williams FW15C and FW16, with the former having to complete a race distance without refuelling and the latter requiring at least one fuel stop.

Increasing the wheelbase allows for a greater plan area under the car to take advantage of ground effects, but another reason of increasing the wheelbase could be to afford the vortices and and flow structures enough time to be turned and managed along the sides of the car and the step plane underneath so the rear can make effective use of them?

bhall II
bhall II
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Joined: 19 Jun 2014, 20:15

Re: Short wheelbase Vs Long wheelbase 2011

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It's an interesting question.

I imagine it's easier to package everything in ways that don't screw up a car's CoG given a 2m track width versus the current 1.8m. The FW16B (top) looks a lot tighter.

Image

That said, there is an aerodynamic benefit to bodywork with larger-radius curvature, as it won't generate as much lift as smaller radii, and it's easier accommodate such a design with a longer wheelbase.

Added length should also give greater directional stability, i.e. less agility. But, I'm not particularly well-versed in that area, and I don't know the degree to which it may or may not make a difference in terms of performance. I'd love to know more if anyone has something to offer.

OO7
OO7
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Joined: 06 Apr 2010, 17:49

Re: Short wheelbase Vs Long wheelbase 2011

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bhall II wrote:It's an interesting question.

I imagine it's easier to package everything in ways that don't screw up a car's CoG given a 2m track width versus the current 1.8m. The FW16B (top) looks a lot tighter.

That said, there is an aerodynamic benefit to bodywork with larger-radius curvature, as it won't generate as much lift as smaller radii, and it's easier accommodate such a design with a longer wheelbase.

Added length should also give greater directional stability, i.e. less agility. But, I'm not particularly well-versed in that area, and I don't know the degree to which it may or may not make a difference in terms of performance. I'd love to know more if anyone has something to offer.
Yes, the FW16 is definitely tighter at the rear. I think perhaps the smaller fuel tank allowed the engine to be pushed forward.
Even today the engineers seem to chase longer wheelbases under stable regs. The Mercedes W06 appears to have a noticeably longer wheelbase than the W05 for instance. Internally the packaging between the two is very similar, however I don't think there are any profile images of both with the engine cover and side pod covers removed for comparison(there is one of the W06 somewhere though). I presume most of the lengthening took place with the gearbox casing.