First this isn't in the tech forum cause its not specifically FC..
Discussing things in one of those "what if...?" chat sessions with a friend we were going over questions about wheelbase, suspensions.. etc Specifically in relation to rocker to pushrod conversions and such.
Some questions I had.
Is there a standard wheelbase/track for FF/FC? (couldn't find the dimensions in the GCR.. unless it's before the F car specs)
Wheelbase is tricky of course... longer is more stable, but shorter rotates better. So in the end, what do you take into account if you were to build other than driver size, feet behind the wheel rule, and engine/gearbox? For instance, a F-SAE car, built for non roadracing.. would they go for shortest wheelbase allowed at the expense of stability? Or if you are building a roadrace car.. do you try for as long a wheelbase as you can at the expense of rotation?
Track? I know that handling is effected by changing the ratio of front to rear (used to do it on our karts all the time)but is wider really better? (taking out the aero adantage of narrow cars)
Pushrod conversion? So the advantage of pushrod is that you make the a-arms do one thing and not two.. and that then they can be lighter, and that you are then dampening wheel movement, not wheel+rocker flex. Is it an advantage then to swap older cars to pushrod? I have read on here about an old Reynard FC with this done, does it work? is it $ that usually scares people away, or compatibility issues with old chassis?
Bellcrank.. what considerations go into angle, ratio etc. (just going for basic cause/effect here, I understand this will have affect on the motion ratios which then in theory will change optimum spring rates..but trying to stay away from that for now)
Knowing that different motion ratios do have an affect on spring rates, what is better? When designing the pushrod bellcrank issue, do you want to aim for a higher spring rate, or lower?
Jon K
(no i am not trying to convert the 88 Van Diemen into a full pushrod car)
It's probably nice to design a motion ratio that creates a significant amount of shock movement. Then the shocks will better play a role in tuning.
The drawback to rockers (at least what I found) was that when you get real stiff with the springs the motion ratios were such that you might only be moving the shock 1/8" max. So that piston is just "fluttering" inside.
There is a maximum allowable track for FF and FC in the GCR. There is one '95 Citation, I believe it is yellow, that probably is flirting with the maximum track. In a closed wheel car the tradeoff is that if you go wide track you have more aero drag. That is not as much an issue with open wheel cars. Some theory believes that if you max out track the rear tire turbulence less adversely effects the working of the diffuser.
F2000 (classed as FC) has a maximum width of 185cm, as noted in the F2000 Specifications at the end of GCR/FCS 17.1.6.B.4 Interestingly, ex-Formula SV (air cooled) is completely unrestricted in track and wheelbase according to section 17.1.6.B.3.
Sports 2000 is another class with no maximum width specified. (we do have maximum heights, and maximum overhang at each end).
In a closed wheel car the tradeoff is that if you go wide track you have more aero drag. That is not as much an issue with open wheel cars. Some theory believes that if you max out track the rear tire turbulence less adversely effects the working of the diffuser.
