Main hoop Bracing support configuration

Aadil,

You just can't help yourself.

No, you were not wrong to put forth your point. That is the intent of a forum.
What has ruined your presentation has been your sarcastic insistance that you know it all, when as Z pointed out a few posts ago, "Your grasp of the simplest racecar Mechanics is clearly lacking".
You need to accept that as fact and start listening to the help people are trying to give you and kill the smartass attitude!

Pat Clarke

PS,

An old song, especially for you... https://www.youtube.com/watch?v=bqIzAjqtkF0

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Originally Posted by Pat Clarke

Aadil,

You just can't help yourself.

No, you were not wrong to put forth your point. That is the intent of a forum.
What has ruined your presentation has been your sarcastic insistance that you know it all, when as Z pointed out a few posts ago, "Your grasp of the simplest racecar Mechanics is clearly lacking".
You need to accept that as fact and start listening to the help people are trying to give you and kill the smartass attitude!

Pat Clarke

PS,

An old song, especially for you... https://www.youtube.com/watch?v=bqIzAjqtkF0

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aaahhhhh Beatles, nice selection :P

I always grew up with an attitude where i wont take a no for an answer, or change my decision, just because some one said so.

All i wanted was to get a proper answer, which showed the fault in my ways, i presented my points (in a aggressive, smart a** kind of way). Though wrong (obviously, i am no top dog), i did deserve a small explanation at least.

Not going to make a bigger fool of myself, again. So thank you gentlemen for your patience and time. I'll concentrate on making a rule legal car and let vehicle dynamics be saved for another day :)

this will be a better suited song for me:
https://www.youtube.com/watch?v=7S94ohyErSw :P

Instead of thinking about an autocross style course, think of a skid pad. As long as you have enough power to keep the car moving, how will power affect your performance in a skid pad? Same weight, same tires, same suspension, etc... Just different power output. All that will differ between the two setups is the percent of maximum power being used, but each setup will require the same amount to keep the car moving. The only way more power will help is if the radius of the turn is large enough such that your low power engine can not get you up to speed (not really an issue on FSAE courses).

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Originally Posted by Dylan Edmiston

Instead of thinking about an autocross style course, think of a skid pad. As long as you have enough power to keep the car moving, how will power affect your performance in a skid pad? Same weight, same tires, same suspension, etc... Just different power output. All that will differ between the two setups is the percent of maximum power being used, but each setup will require the same amount to keep the car moving. The only way more power will help is if the radius of the turn is large enough such that your low power engine can not get you up to speed (not really an issue on FSAE courses).

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thank you :), the skid-pad case is really interesting, does the same apply to autocross and endurance too?

A Little bit off-topic but won't the single's need more time to reach the same power output when compared to an I-4(assuming same car and set-up), wont this hurt timings and consequently points?

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Originally Posted by carlzxcv

does the same apply to autocross and endurance too?

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That is a question you should be able to answer yourself chap. Have a stab at getting a lapsim-type-tool together and make some predictions. Or get your hands on OptimumLap somehow, it was free to get hold of last time I tried. A process like this should be what is driving your engineering decisions.

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Originally Posted by CWA

That is a question you should be able to answer yourself chap. Have a stab at getting a lapsim-type-tool together and make some predictions. Or get your hands on OptimumLap somehow, it was free to get hold of last time I tried. A process like this should be what is driving your engineering decisions.

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will do, thanks for the help :)

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Originally Posted by carlzxcv

thank you :), the skid-pad case is really interesting, does the same apply to autocross and endurance too?

A Little bit off-topic but won't the single's need more time to reach the same power output when compared to an I-4(assuming same car and set-up), wont this hurt timings and consequently points?

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I don't think the string of victories around the world of singles trumping I-4s has consequently hurt points. OH! BURN!

You may be considering one point, on corner entry, what in your mind seems to be Spa Francorchamps high speed track where the cars are power limited before entry, in fact it's more likely that average corner entry speed is in the 15 - 35 mph range. The corners dealt with in FSAE also will turn your thinking on it's head. Lateral acceleration is awesome, but the turns happen so quickly it's more of a yaw and stability limited event for autocross and endurance to a point. Steady state cornering is nothing but a fleeting dream. The faster you can get through the transition stages of into and out of a corner, the less steady state matters. Dylan is spot on above.

I hope that the terms yaw, yaw moment, and stability are not new to you. If they are, please read up, they'll be very useful.

As a counter point to your bhp/ton having an influence on cornering acceleration. I would like to propose that power output has no effect on potential cornering ability of the vehicle. However, the mass change that you are taking into account when comparing vehicles is most of the difference.

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Originally Posted by carlzxcv

Now consider a hairpin bend of radius 4m at the end of a 60m strech, Can you please tell which car will generate more cornering force.

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No one other than the FEA guys care about cornering FORCE because it is not a normalized value. A semi truck navigating that corner will generate a whole lot more FORCE than that puny little M3!
However, who gets around it faster? Why? Is it because the M3 generates more acceleration? OF course!

Now. I have this really cool thing I built. It's called a drift trike. It's a lot of fun. Here's the catch: it has 3 wheels and a 5hp motor, yet it will out handle a car on small radius corners. Can you think of why this is possible? I'm interested to hear your conclusions. Don't be shy. :)

Everyone is here to help each other. Take advantage of what they have learned, but please don't insult them.
And with that, I leave you with a gift of an on car video demonstrating what I mean about fleeting steady state from two of the best drivers I've ever known from FSAE. Also, it's powered by a single. ;)

https://www.youtube.com/watch?v=MQwQsAhAjVY

Some real good advice from lots of experienced people here. I know the horse has been flogged quite enough, but it is not quite dead, so further to these comments and my own previous comment, I would like to add an exercise I recommend to understand the real importance of horsepower during an event:

Pick the peak horsepower levels of two engines you are considering, a higher and a lower. Instead of plotting the usual engine torque vs rpm graph, you should make a similar graph for the full vehicle. If power = torque x RPM for an engine, power = 'tractive force' x 'vehicle speed' for a car. Plot out the 'tractive force' that would be created by a car with each chosen engine at a range of speeds and compare curves. What you have here is the actual tractive force that will reach the tyres at all vehicle speeds with an engine of chosen power level fitted, but with a gearbox of infinite ratios allowing peak power level to be maintained at all vehicle speeds. Real life will not be too different, at least not different enough to negate the usefulness of the exercise, go with it for now.

Check your units and format your graph; have tractive force plotted against vehicle speeds up to say 50mph. Seems reasonable as I'm sure you won't be exceeding 50mph for much of an event.

Now pay attention to those force values. If in Excel, write an IF function capping tractive force outputs to below say 3000N. After all, let's assume each car has the same tyre and can only output the same amount of tractive force (we have assumed each car is a point mass (no weight transfer), is of equal mass (1500N) with a tyre mu of 2). You should be able to see the speeds up to which the engine with more power has NO advantage over the other; at these speeds BOTH cars are traction limited. This is a very useful first step, and should visually depict for you in quantifiable amounts what everyone above is trying to explain to you.

Another key thing to picture here is that you have so far only compared tractive force outputs against the grip capacity of a set of tyres during straight line acceleration. If your tyre has to give out some of that grip force as cornering force because the car is still exiting a corner, the threshold speed below which both cars are effectively equal will increase again. Try and incorporate a friction circle and a generic FSAE-event-corner into the above plots to see this if you can't picture it from my words.

So you can see the speeds above which the engine with more power is giving you an advantage. And you can roughly quantify this advantage; at a chosen speed, engine 1 can output X newtons, engine 2 can only output Y newtons. Now the next step is to quantify how often you will be in those upper speed ranges during an event, and to then make the whole-lap-performance comparison between the benefit of the higher-power output engine at these higher speeds, and the benefit of the lighter lower-power engine in every single corner you get.

Which is the best engine option? We'll leave that to you to work out, but I dare say you'll find a big clue in MCoach's video.

A good lap-sim should bring you to the same conclusion. What I've described above are effectively the first-steps of the generation of a simple lap-sim. And you can be sure that other teams have used this approach to arrive at the decisions they made; don't forget how many successful teams now turn up at events with singles.