My FSAE Car Designing Diary - [T51r]

[t51r]

i believe not only lateral load transfer...more issues must have been considered to get those numbers like...avoid rear wheel hitting cones while clipping cones(this is what i know)

 

[cqloh]

if you're hitting cones it basically means you have a bad driver, period.

you don't forgo grip to compensate for incompetence...

its sort of like saying "i'll reduce the rear track on an F1 car so my driver doesn;t clip the wall exiting the corners in monaco"... thats not a valid consideration because if you do reduce overall grip you end up doing more that clipping the wall you end up being the wall...

there is no consideration when it comes to grip.. you only compromise by doing what is need for the driver to do their job.. if the driver can't avoid the cones with grip.. what makes you think he can avoid the cones without grip.

so there you have it.. clue No.2... it has to do with the overall grip of the car

 

[cqloh]

don;t tell me you guys can;t be bothered to find an answer and expect me to tell you?

 

[xtremeleo]

interesting, sorry for not participating cq..

because transfer of torque? the larger the wheel base, the larger the torque transfer to the rear wheel to obtain grip on acceleration..?

t51r, the samllest downforce pun helps.. there r no substiture for grip, even weight can be countered by increasing torque, up to sum level lah..

 

[siputmagic]

sorry cq for not participating in this forum for a while..been very busy with assignment..
i've a copy of miliken books..which data you want? is it from good year tire data?

as for the camber gain, which of the setup in the graph below is consider good? each of them have different double wishbone setup...

 

[cqloh]

do you have numbers for roll center change in roll and ride for those set ups as well?

generally i'd op for the setup with the least amount of rollcenter offset unless you have tyre data..
camber change is one of those double edged swords...

i can;t tell much from your curves.. you seem to have only .5 inchs of bump travel and 1 inch in droop... why have you done that? if any, i'd limit my droop travel unless you were on a very bumpy course ie rally.. the reason is that you would never want your car to go into positive camber in droop..
i would forget the pink line.. parallel arms have no place in race cars... they found that out in the 70s... the reason being that your front view swing arm is at infinity.. that causes other geometric problems.. and you certainly would not make them level... the last thing you want is for the cars shocks to extend on braking...

 

[t51r]

dont be disappointed..... we know the formula.....wider track width reduce lateral weight transfer. due to nature of tire, the lateral force gained at outer wheel is always less than lateral force loss at inner wheel, so too much lateral weight transfer would reduce the performance of a car in corner. so wider track width reduces total lateral force loss.

would you have a fsae car with much wider track width than others to compete in FSAE by giving a reason to have more grip in corner? 2 cones is likely to be only 2-3m apart and the chance to hit cone is also higher, 2 sec penalty is given for hitting a cone and there are countless cones you have to slip in a lap, i think rear wheel hitting cones is worth to consider in FSAE event, however in racing circuit like sepang is not applicable. how do you think?

siput, your designed bump and droop travel is way too less....that graph does not fully describe the trend of camber change. commonly 2-3inch bump and droop travel is chosen in fsae, however the number comes from your analysis and consideration.

 

[xtremeleo]

thanx for the explanation cq, i'll try to digest d info given

 

[cqloh]

would you have a fsae car with much wider track width than others to compete in FSAE by giving a reason to have more grip in corner? 2 cones is likely to be only 2-3m apart and the chance to hit cone is also higher, 2 sec penalty is given for hitting a cone and there are countless cones you have to slip in a lap, i think rear wheel hitting cones is worth to consider in FSAE event, however in racing circuit like sepang is not applicable. how do you think?

yes i would... simply because FSAE is a design event more than it is a race competition... you would gain more points by stating that you have forsaken hitting cones for lateral grip in the static event..
hitting cones might cost you a 2 second penalty.. but the weight on the design part is heavier..
alot of guys in FSAE get caught up in the dynamic events that they forget about the static events...

again.. you can train your driver not to hit cones.. but you can't train your car to have more lateral grip.... so as the saying goes.. you need to spend the same amount of time testing the car as you did building the car... a handful of FSAE cars are tested for the first time 2 months before the competition.. some 1-2 weeks before.. most have their first testing session on the first day of competition... so its not uncommon for a driver to hit the cones... practice and testing is what gives you a good chance at winning a race..


most FSAE cars have a shorter track at the rears because they are set to oversteer.. not because they want to avoid cones..

Bump: i deleted my post... there are too many people out there that do not grasp the concept enough to use...

t51r.. i'm glad you understand what i was trying to say.. now you just need to apply it to a real car and see the changes for yourself... sometimes you have to go against principles and theories to get the results.. not bad.. so maybe there is a future for motorsports in malaysia..

Bump: i deleted my post... there are too many people out there that do not grasp the concept enough to use...

t51r.. i'm glad you understand what i was trying to say.. now you just need to apply it to a real car and see the changes for yourself... sometimes you have to go against principles and theories to get the results.. not bad.. so maybe there is a future for motorsports in malaysia..

 

[t51r]

you can train your driver not to hit cones.. but you can't train your car to have more lateral grip


most FSAE cars have a shorter track at the rears because they are set to oversteer.. not because they want to avoid cones..

Good points.... thx cq:wavey:
(i had forgotten these points)

 

[t51r]

going to get the data from uni today....not sure if i can get full data....

anyone wan a copy of RCVD? pm me if u wan...i wont give the detail here...it is against the copyright ^^

 

[xtremeleo]

email me at [email protected]

i want to understand more on dis, tq very much