Acceleration times

[Iloper]

Still excited about our accel. time in Baltic open, I'm asking for your best time in this event, during testing or training.

Our time with the Chalmers 06 car was 3.75s and 109 km/h.

Helsinki wasn't far behind with 3.77s with there 06 car.

As far as I know this is the best time in any event. Wich makes our car the fastest in the world...

Am I right?

/Per
CFS

[Peter]

Wich makes our car the fastest in the world...


No offence, since when is FSAE all about straight line acceleration? IMHO the fastest car is the one with the highest overall score from the dynamic events.

Peter
Delft (where less is more http://fsae.com/groupee_common/emoticons/icon_wink.gif)

[kwancho]

Yeeesh 3.75 is fasssst. Remind me, what'd you guys do at West? What made the big difference?

[MH]

Just to add to the discussion: exactly how were the times measured? With a transponder mounted at the rear end of the car, or by other means? How exact were those 30cm behind the line? How many runs did the teams get? What kind of surface? Obviously, al these things have a big influence on your times...

What I mean to say, you really can't compare the times from different competitions, so saying you have the fastest car is a bit too much. No offence intended though. You guys have a very nice car http://fsae.com/groupee_common/emoticons/icon_wink.gif

MH

[Bill Kunst]

There is a difference between fast and quick. You may not have the fastest(topend) but you may have the quickest(accel). Anyway it goes, I am not going to jump on here like others and shoot down your joy of a substantial accomplishment.

Sure, Fsae isn't about accel, it's about everything. But then again, when was the last time that you saw the 1st place car win every event. I am sure that when they won, no one ws standing there saying "Duuuuhhhh, we beet ya in dat der dollar purt a da comp." We jacked them off repeatedly for weeks on there accomplishments, as anyone should. And why shouldn't the other guys get to do the same for something no one is recognizing them on the forum for?

Oh well, I think RMIT cheated, maybe they had sex with the judges. The Toronto driver was on steroids. Texas A&M's car had the ability of human though and drove itself and gave its own presentations.

Give credit where due,
Congrats Chalmers, and don't take some asses ball busting cause they have a small pair.
Bill Kunst

[MH]

Just to be clear: I really like the Chalmers car, it looks and sounds fantastic.
All I'm saying is that a time of 3,75 is amazing, but you should consider all the circumstances before claiming you have the fastest car in the world.
For example the guys from Graz claim 3,6 sec runs regularly during testing, does that mean THEY have the fastest car in the world?

@Bill: after reading your deep, meaningful and well-arguemented post, I'm really curious: does your post mean YOU have a big pair????

MH

[Iloper]

That was just what I was asking for, and it doesn't suprise me that a car like Graz can run that fast under good conditions. Electronics is also important to run stable times.

Unfortunately we don't have any electronics yet, therefore we see a great viriation in our times.

In Finland, Delfts fotocell timing system was used. Thankx for that by the way, Delft!

Otherwise the conditions in Finland were pretty good. Tarmac was nice, and tyres were pretty warm. But we ran on our England tyres, they were a bit slippery.

Alex Kwan: The difference from USA West is a supercharger. Mounted on a completely new vehicle... The car you are talking about, also known as the "Volvo car", is our -05 car, this is our -06 car.

You might see it in West next year.

/Per

[Bill Kunst]

MH,
What is your name, where are you from, and all the rest?

I think that you can read pretty close to the type of personality each person has on here. I am merely trying to defend someone who was excited about how well they did and was asking "Is our car the fastest?" I just found it annoying that lloper and chalmers gets slammed because you need proof that they are fastest. Maybe we should have all the cars at one event. How do we know that the winner of FSAE west is really a championship car? Sure, you cannot compare the scores on events to scores from other events. But I think, just short of them running the car in a vacuum, accel times could be compared. Hell, a person who had doubts could have said something like, "If its not the fastest, it got to be one of them for sure! Congrats!" And then that person could have sat at home and stewed over it.

Bill Kunst

[Jersey Tom]

Under 3.8 is awfully quick. Never heard of an SAE car that fast. 4.0 wins in the US in the dry

[kwancho]

Originally posted by Iloper:
Alex Kwan: The difference from USA West is a supercharger. Mounted on a completely new vehicle... The car you are talking about, also known as the "Volvo car", is our -05 car, this is our -06 car.

You might see it in West next year.

/Per

Ah, sweet. Bring it to West!

[CMURacing - Prometheus]

IIRC, Ohio State had a 3.98 to win FSAE a number of years ago (late 90s?). Texas A&M has told us that they've run 3.5s in the College Station heat, on asphalt, with hot tires.

Sorry to ruin your day.

[repeatoffender]

Firstly before i start my rant id like to say congratulations to chalmers for their fast time.

Its not as easy as you think, and so far everyone has come out asking some fair questions but have neglected some things. What about tail wind or head wind, what about the launch you get. A good launch makes all the difference. And thats where most teams find repeatability an issue.

On a more serious note, it doesnt really count unless you set the time at comp. I know my team has run under 4 seconds, and recorded 3.6s on concrete, but because no one else (officials / other teams etc) was there to back it doesnt make it believable.

Fair enough if they did it, well done. But its not officially the fastest time.

[kwancho]

Uh... his post says they did it at the Baltic Open. There were 4 teams (Chalmers, Delft, Helsinki and KTH, an elite group for sure) and 7 cars.

[Jersey Tom]

Regardless.. the point being made is - you can be as quick as you like in testing and practice, but the competition numbers stick.

..wait, is there a point being made?

[Iloper]

Here is a clip of the 3.75s run:

http://www.youtube.com/watch?v=gLYHaQfOAlc

Enjoy it!

/Per

[murpia]

Originally posted by Iloper:
Here is a clip of the 3.75s run:

http://www.youtube.com/watch?v=gLYHaQfOAlc

Enjoy it!

/Per
Either that clip suffers from an optical illusion or that track slopes downhill towards the end...
Regards, Ian

[Jersey Tom]

I drank a beer in .02 seconds. Fastest in the world.

Thats how the CU FSAE/drinking team rolls.

[Kimmo Hirvonen]

I have to admit that in Baltic Open there was a small downhill which began in about half the way of 75m and lasted till the finish. Here's a video which contains the same run from a different angle and with speed radar reading:
http://www.formula.stadia.fi/videot/BO_Chalmers_acce.mpg

Here's also a video from our run in FSG, which might be one of the fastest in official competitions:
http://www.formula.stadia.fi/videot/FSG_Helsinki_acce.mpg

Both of these runs' times were taken with photocell system and just out of curiosity, has anyone else measured how much does it affect on time if the transponder is mounted at the rear of the car or if the time is taken with photocell system. We have done some testing with this. We put the transponder to the front of the car and then to the rear and the time difference supprised me quite a bit. We got 0.15-0.25 second differences with this so it seems that it really affects the time a lot.

[murpia]

Originally posted by Kimmo Hirvonen:
I have to admit that in Baltic Open there was a small downhill which began in about half the way of 75m and lasted till the finish.

Both of these runs' times were taken with photocell system and just out of curiosity, has anyone else measured how much does it affect on time if the transponder is mounted at the rear of the car or if the time is taken with photocell system. We have done some testing with this. We put the transponder to the front of the car and then to the rear and the time difference supprised me quite a bit. We got 0.15-0.25 second differences with this so it seems that it really affects the time a lot.
Here's a few 75m times from a simulation of a 'generic' FSAE car:
0m staging 4.45s
0.3m staging (as competition) 4.20s
1.0m staging 4.00s
2.5m staging (roughly equivalent to rear transponder with 0.3m car staging) 3.75s
Getting the car rolling is key. That last car is already doing ~18kph when the timing starts...
Regards, Ian

[PatClarke]

As far as I know this is the best time in any event. Wich makes our car the fastest in the world...
If your course went down a mineshaft rather than down a hill, you might go faster!
Acceleration times are only relevant when comparing one team against another on the same course. Claiming a 'World record' from an event that was gravity assisted is juvenile at best.
Pat

[Bill Kunst]

He did ask if he was right. The part of the quote you cut off. That would be juvenile, like the AP that seems to reshape all quotes to make people look like asses or heroes.
Bill

[JR @ CFS]

Christ ladies, put the handbags away! We are all suppose to be working towards becoming professional Engineers! This isn't how you deal with the feeling of being threatened because someone elses todger is bigger than yours, is it! Save it for the competitions! If you are at the same competition and do a faster time than them in an acceleration run, then thats all you need to do!

[Chris Davin]

The SAE considers the main US event (Formula SAE) to be the "world championship," so the "world's fastest car" title would probably go to the car that scored the most points in the four dynamic events (not including Fuel Economy) at that competition. Everyone should know that there is much more to winning FSAE than having a fast car.

Comparing acceleration times at different locations is silly. So is using acceleration time to judge how "fast" the car is, or even how good the engine is.

[flavorPacket]

Adding more fodder to the fire...

that says 3.635 if you can't read it

http://img210.imageshack.us/img210/4540/accelediteder4.jpg (http://imageshack.us)

http://img210.imageshack.us/img210/4540/accelediteder4.th.jpg (http://img210.imageshack.us/my.php?image=accelediteder4.jpg)

[Boston]

Just to rain on U of M's parade, i'll go out of my way to point out that the above time is from this year's Goodyear Shootout, where the accel event was 75 yards (instead of meters), I understand. (6.5 meters shorter than an FSAE accel event).

[flavorPacket]

As soon as we saw the times, we thought that the course was short. But, NC State won accel at East with a 3.95, and ran a 3.90 here. It's not everyday that somebody runs under 4 and only gets 60 points.

[Ecks]

To back up flavorPacket's assertion, it should be noted that we did a significant amount of testing with 3rd gear launches with no gearshift during the run. In those cases, we had the engine hitting the rev limiter on average .08s after crossing the finish gate, which works out to about 2.5 m distance past the finish. In our first accel run at the shootout, this no-shift strategy resulted in us hitting the rev limit 3.67 secs after launch, according to logger data. That's .05 sec short of our accel time. which works out to rev limit coming about 1.6m short of the finish gate. Had the course been a whopping 6.5m short of a true accel run, we would have never even come close to the rev limiter.

For the record, our data shows a 0-60mph time of 3.07s. Nicht schlect.

In addition, Michigan State posted a time of 4.025, a bit off their FSAE West accel winning time of 3.894.

I'm willing to bet the the people at Goodyear know the difference between meters and yards. Our data shows it. Our competitors times show it.

[murpia]

What timing system was in use? Further up the thread you can see some data for the effect of transponder timings rather than beam.

Regards, Ian

[Scrappy]

Looking at the times from goodyear from a statistical standpoint, red flags are raised for me when I compare the number of teams running under 4 seconds at 2007 East and West to the number that ran under 4 at goodyear.

These figures all take into account the number of teams that actually had a score for acceleration, not the number of teams registered at the events.

07 East - 73 teams competed, 2 teams under 4 seconds.

07 West - 45 teams competed, 6 teams under 4 seconds.

Goodyear Shootout - 14 teams competed, 6 teams under 4 seconds.

Based on these stats, it would seem to me that one or more of the following conditions would have to apply at goodyear to produce these kinds of times. Either the track surface and conditions were amazing, and everybody was hooking up, everybody who came had perfected their accel runs prior to goodyear , the event only hosted the fastest teams in the nation in acceleration, or the track length/timing were messed up.

Having driven there and watched accel there, I can rule out the surface and conditions being amazing for the accel event, I didnt see anybody getting a fantastic launch. The surface/conditions were no where near the conditions at West, where the tires were piping hot, and people were hooking up so hard it made the event look easy. As far as everyone perfecting their accel runs, we all know it would be highly unlikely that everybody who competed had their accel nailed down. Although there were some very fast teams at goodyear, in no way was it a collection of the fastest accel teams in the nation.

This leaves the possibility of the timing/length of the track being screwed up. Everyone had to use the same AMB style transponders we used in this year's competitions, so the timing method should have been consistent between all three comps. During the course of the day, I had overheard that the track had been incorrectly set up at 75 yards, not 75 meters, and that had been what we ran on. This would seem to account for the statistically amazing times that were recorded that morning. thats my story and im sticking to it.

[flavorPacket]

Jeez, look what happens when you try to share something. Yeah, it most likely wasn't REALLY a 3.635. But, Michigan was still faster than everyone by a large margin, and the other teams build fast cars.

I don't understand how you can say the event didn't have the fastest teams around. Sure, there were plenty of fast teams missing, but UW won East, NC State won accel at east, State won accel at West, toledo is also very fast, cincinatti was 4th at east and also good at student, Oklahoma won autox at east and more, etc.

Furthermore, the track temp was at least 95 F, which is plenty.

FYI the transponders were not used for accel, but rather photogates like at east

[Scuba]

As it has been said earlier in this post, Who Cares?!! It sounds to me like some of you are trying to rationalize why you were slower in acceleration. The fact is you lost in acceleration by almost 0.3s or more at that competition. Learn from it and move on!

Would you like some cheese with your whine?

[VFR750R]

i can't believe no one has suggested they soaked their tires...not that i'm suggesting that. jkhttp://fsae.com/groupee_common/emoticons/icon_wink.gif

[Ecks]

Yeah man, Hot Lap's good for 2 tenths. Only works on Hoosiers, BTW...
There's a saying about a bridge that goes with this.
javascript:void(0)
Cool

[Adam Zemke]

And who would dare run Hoosiers at a Goodyear-sponsored event? http://fsae.com/groupee_common/emoticons/icon_smile.gif

[flavorPacket]

people who enjoy having wheel and tire assemblies that weigh the same as a 13" D2692...

[VFR750R]

Ecks, tire soaking is no joke. Ask any bandalero, legends, midget race car driver. And although I'm sure the extent of the help is dependent on the tires orginal tire compound, i can garuntee you can make goodyears stickier too. Even having some residual VHT would be an advantage.

[screwdriver]

Originally posted by Kimmo Hirvonen:
Both of these runs' times were taken with photocell system and just out of curiosity, has anyone else measured how much does it affect on time if the transponder is mounted at the rear of the car or if the time is taken with photocell system. We have done some testing with this. We put the transponder to the front of the car and then to the rear and the time difference supprised me quite a bit. We got 0.15-0.25 second differences with this so it seems that it really affects the time a lot.

Placing the transponder on the rear is the same as if you'd start that distance ahead of the light-barrier. If you think about when the system starts and stops the timing, it's fairly obvious. An optical system starts and stops the time as soon as the first bit of the car passes the sensor, while your transceiver-system starts the timing when the transceiver passes the receivers.

We've worked out that starting 1m ahead of the light barrier, chops off about 2 tenths of a second on our test-track with our optical timing system.

You have to be careful with these assumptions though. There are various ways, starting and stopping of the time can be triggered. A few examples:
Optical
* trigger when object has fully passed
* trigger when first bit of object passed
Transceivers:
* Start on first movement, stop, when you move away from both receivers
* start on change between "towards, towards" to "towards, away from", stop on change to "away, away"

In the end it holds true, that you can only compare the times of the cars under the same conditions.

For the record, our PW2.07 (the 07 car) was clocked 4.33s in Hockenheim 07, the PW06 (the 06 car) held the fastest ever recorded time in an official event of 3.86s for about half an hour, before Helsinki took first in that competition.
Since Hockenheim, we made some adujstments to the 07 car, which gained us .2s on our test-track. Let's see what we can do in Australia.

[Egan]

this is extremly late cause i just joined but WPI got 0-60 in under 3 sec

[murpia]

60 what, measured how?

Reading that post is sounds like you're proud to calculate -60 in your head that fast...

Regards, Ian

[Egan]

0-60 mph
and i'm not the one who calculated it.
I was just reporting data that I saw
here's the link go ahead and look (http://users.wpi.edu/%7Efsae/car.html)
look under performance.

[flavorPacket]

Egan, that's not exactly hard data. Post an integrated acceleration curve or wheelspeed data or something. I can make up numbers just as well as the person who wrote that website, bit it doesn't make my car any faster.

[Egan]

I'm sure its not hard data. I was just putting in what I saw and what I had heard. I'm not trying to say that the WPI car is amazing.
(o and i don't have any integrated acceleration curves or wheel speed data sorry)

[exFSAE]

Pff my old Jeep YJ did 0-60 in like 1.78.

[Wesley]

I met a guy who claimed 0-60 in 3 seconds in his Chevelle, and also only claimed 500HP.

[VFR750R]

Originally posted by Wesley:
I met a guy who claimed 0-60 in 3 seconds in his Chevelle, and also only claimed 500HP.

Very acheivable if he had a 4 link and was setup for drag racing. cars can leave HARD with alot of tire and the right geometry.

[Matt N]

If my memory serves me correctly, for a slick tired drag car (no tire spin) of the following speed

quarter mile 9.90 sec, 137mph

during the same run the driver experiences

0-60 ~1.8 sec
first 60 feet 1.25-1.35 sec

550 hp in 2100 lb will do the trick.

[Wesley]

Originally posted by VFR750R:

Very acheivable if he had a 4 link and was setup for drag racing. cars can leave HARD with alot of tire and the right geometry.

Well, getting a 4,000lb car to go that fast is an achievement, especially when I asked him what he had done to it, and he said "A cam and headers"

The average drunkard that wanders by to look at our car during home football games always has a car that is faster, I could claim our car could fly.

[VFR750R]

The extra information definitely changes the story. He probably runs 0-60 in 6 seconds.

I imagine the story goes like this; he beat some squid on a 600F2 light to light, and since F2's go 0-60 in 3 seconds...

I've heard it a million times if u replace chevelle with civic and any 14 sec car like a 350z or wRX for the F2.

[Gruntguru]

Sorry Pat but acceleration time down a vertical mineshaft for 75 meters and zero wind resistance takes 3.912 seconds - not quick enough!

[PatClarke]

Okay okay Guru,
I raise my hands and surrender =] =]

Maybe gravity is different where I live ;-)

Pat

[L B0MB]

Accelerating down a mine shaft would only be possible due to gravity as there is no normal force acting on the tire and hence no tire grip. Thus the engine cannot aid in acceleration... perhaps it could slightly if the intake was positioned at the leading edge to provide a suction force and the exhaust mounted at the rear to provide thrust... this is still assuming no wind resistance...

Maybe gravity is different where you live Pat :P

[dazz]

I like these completely ridiculous hypothetical’s... If the side of the mine shaft was smooth flat bitumen, then some very aggressive down force wings could be used to allow the car to accelerate. So the equation would be accel due to gravity - vertical wind resistance (drag) + powered accel. Someone like Monash could use their existing data and actually run the calcs for this highly unlikely scenario!

[PatClarke]

Ah, but can you accelerate UP a mineshaft? =]

Pat

[VFR750R]

Maybe not a mineshaft, but up the empire state building with enough ramp at the beginning to reach 'critical' speed before going completely vertical.

With wings of course.

[PatClarke]

I would buy a ticket to see that http://fsae.com/groupee_common/emoticons/icon_smile.gif

No parachutes permitted by order of you know who http://fsae.com/groupee_common/emoticons/icon_smile.gif

Pat

[Bemo]

I'd also love to see that, please post a video after that event http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[L B0MB]

perhaps that could be the method of testing teams aero devices!

i'm not sure how easy it would be to get insurance for that event though...

[Wesley]

Or, upside down!

[dazz]

Originally posted by VFR750R:
Maybe not a mineshaft, but up the empire state building with enough ramp at the beginning to reach 'critical' speed before going completely vertical.

With wings of course.

Well, Robbie Maddison, using no aero, left the top of a ramp & accelerated (@ roughly -9.81m/s^2) to the top of a scale replica of the Arc De Triomphe on new years eve in Las Vegas. Does that count?

[PatClarke]

Nope! Because the replica Arc prevented him from falling back down =]=]

In all seriousness, I doubt an aero car could actually climb very far up a vertical surface, I doubt the vehicle would be able to maintain enough forward (upward) speed to maintain tyre contact. Can a FSAE car maintain acceleration above 1G at a speed high enough to give sufficient aero download to ensure traction?

VFR I would like to call you on your clam to be able to climb the Empire State regardless of your approach speed =] =]

What started off as a smartass throwaway comment has begun to intrigue me http://fsae.com/groupee_common/emoticons/icon_confused.gif

Pat

[VFR750R]

Originally posted by PatClarke:


In all seriousness, I doubt an aero car could actually climb very far up a vertical surface, I doubt the vehicle would be able to maintain enough forward (upward) speed to maintain tyre contact. Can a FSAE car maintain acceleration above 1G at a speed high enough to give sufficient aero download to ensure traction?

VFR I would like to call you on your clam to be able to climb the Empire State regardless of your approach speed =] =]



Pat

My clam included you having to reach 'critical' speed before going vertical.

You are probably right that no FSAE car has enough power to weight ratio to accomplish the feat. I would assume that most FSAE cars reach terminal velocity on flat ground before their wings provide force equal to their weight. BUT, wings are such cool devices that you can get much more downforce then drag so I think it is quite possible with a more powerful car.

As it were, a two wheel drive fsae car with tires of u=1, would need its REAR downforce to equal the weight of the car, so total downforce would be probably close to 2x the weight of the car. The higher the CG the more front downforce would be required to keep the car from flipping backwards, so front downforce is required. And then it would only be able to maintain speed, not accelerate to higher speeds as it climbed.

Regardless of wing design the car would have to be capable of accelerating at 1g on flat ground at the speed required to get 2g of normal force. If that speed happenend to be 100mph for a 650lb car w/driver that would take 173 horsepower + the drag horsepower. With 2:1 force/drag wings the horsepower needed would be 346hp total. Regular non-wing drag would also have to be added in. Turbo busa FSAE car.

Although it might be 'cheating', all wheel drive or stickier tires will reduce the amount of downforce (and power) required to balance the force diagram.

[L B0MB]

Even if you could drive up the Empire State building, what do you do when you get to the top?

Perhaps build an ramp that arcs over the apex so you can drive down the other side... But then, will there be sufficient downforce at that speed to achieve the radius at half the building width? (centipetal force for that speed and radius would be the miniumum required to avoid flying off into thin air)

[Wesley]

Originally posted by PatClarke:
Nope! Because the replica Arc prevented him from falling back down =]=]

Pat

So since he left the ramp with a ballistic trajectory and it was a great accomplishment to make the jump, both his trip and his landing occurred on an arc of triumph...?

[PatClarke]

Yeah, that sounds about right =] =]

Personally, I think he needs his head read.

And if one were to build a tower climbing FSAE car, I think it would have to be FWD! Think about it

Cheers
Pat

[VFR750R]

Originally posted by PatClarke:


And if one were to build a tower climbing FSAE car, I think it would have to be FWD! Think about it

Cheers
Pat

Good Call!!

[murpia]

I don't think a car built to FSAE rules could climb a wall or drive on the ceiling.

But, a car could possibly be built that could achieve either of those goals as long as it is allowed to gain speed first, then transition onto the wall or ceiling.

The requirements are that the car has a) sufficiently high power, b) sufficiently high downforce, c) sufficiently low L/D, and d) sufficiently grippy tyres.

Calcs have been done that suggest that F1 cars on F1 tyres can drive on the ceiling above about 150kph. The key is to have sufficient downforce to generate the weight of the vehicle plus enough traction to maintain constant speed by balancing drag. That's where the L/D requirement comes in.

To drive up a wall seems harder at first inspection, although 4WD coupled to F1 spec aero might be enough to achieve it.

Regards, Ian

[VFR750R]

Originally posted by murpia:
I don't think a car built to FSAE rules could climb a wall or drive on the ceiling.

But, a car could possibly be built that could achieve either of those goals as long as it is allowed to gain speed first, then transition onto the wall or ceiling.

The requirements are that the car has a) sufficiently high power, b) sufficiently high downforce, c) sufficiently low L/D, and d) sufficiently grippy tyres.

Calcs have been done that suggest that F1 cars on F1 tyres can drive on the ceiling above about 150kph. The key is to have sufficient downforce to generate the weight of the vehicle plus enough traction to maintain constant speed by balancing drag. That's where the L/D requirement comes in.

To drive up a wall seems harder at first inspection, although 4WD coupled to F1 spec aero might be enough to achieve it.

Regards, Ian

Great Insight Ian http://fsae.com/groupee_common/emoticons/icon_wink.gif

[samphlett]

Wouldn't you run into fuelling problems if the tank is upside down?

[dazz]

Originally posted by samphlett:
Wouldn't you run into fuelling problems if the tank is upside down?

Not to mention the challenges of keeping an oil pressure feed to the engine & then getting it back out of the cases. Scavenger port locations, dry sump tanks upside down? Gearbox, diff & brake fluids all become problematic as well. Nothing a group of talented engineers couldn't overcome though I'm sure http://fsae.com/groupee_common/emoticons/icon_smile.gif

[oz_olly]

Sure it would be a problem for most existing race cars, but think how many aircraft have over come these problems. Granted alot of aircraft that can fly inverted including fighter jets can have limited inverted flight times.

Cheers

Olly

[L B0MB]

If we moved to rocket engines for propulsion we would no longer require lubrication systems...

[Superfast Matt McCoy]

Every time I read a new post in this thread I think of that Family Guy where Peter is going on about something ridiculous and Brian says "Can I buy pot from you?"

[Wesley]

FWD would be good, since the drag moment around the pitch axis will plant the rear tires and counteract the acceleration pitch moment.

Although a better solution would be suction cup tires! In fact, if we could harness the power of an octopus or gecko, we could probably increase tire mus by a lot!

[VFR750R]

Yeah, VHT might lower the hp required by 100 or more.

[JamesWolak]

Originally posted by samphlett:
Wouldn't you run into fuelling problems if the tank is upside down?


Upside down yes. But if we are climbing a tower then we could change our pick up points on the tank and engine and be alright.

I think the motor for this tower climber ideally would turbo. The turbo would benefit from the additional load of the towers grade. Should be able to make quite a bit more HP from the additional load, it would be well over 100ps like this. Plus you wouldn't be as affected from altitude.

[Kevin Dunn]

Boy, I read the subject title, and shot to the fourth page...Now I'm reading about FSAE cars driving vertically up towers and driving on ceilings.

What ever happened to Keep It Simple Stupid? http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Wesley]

Here on the Sooner Racing Team, "Imagination" and "fun," sometimes take precedence over silly things such as "easy" or "reliable" or "functional"

It's how we stay sane and yet creative. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[Superfast Matt McCoy]

Originally posted by Wesley:
Here on the Sooner Racing Team, "Imagination" and "fun," sometimes take precedence over silly things such as "easy" or "reliable" or "functional"

It's how we stay sane and yet creative. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

Case in point, circa 2006:

http://www.superfastmatt.com/images/ncc-1701.jpg

I looked for 20 minutes to find that picture.

Worth it.

[JamesWolak]

Originally posted by Superfast Matt McCoy:

Case in point, circa 2006:

http://www.superfastmatt.com/images/ncc-1701.jpg

I looked for 20 minutes to find that picture.

Worth it.

Does that rocket need to stay within the plane from the top of your roll hoop to the top of the rear wheels? If so i don't think you're going to pass tech.

[Wesley]

Well, the warp nacelles are capable of twisting time and space in that location to fit into the area behind the roll hoop.

It lets us put things like "Taking into account track surface and variations in the local gravitational field, we have designed our suspension to maximize such and such..." and "I dinna have the power keptin!" into our design report.

[Mikey Antonakakis]

But the intake isn't within the plane...

[rollcentre]

Originally posted by VFR750R:

I would assume that most FSAE cars reach terminal velocity on flat ground before their wings provide force equal to their weight.

I know personally very well one such car that accomplishes it's own weight (with driver in it) in downforce before being drag/gear limited on flat ground. Not bragging, just saying it has and is being done.

This is a fun thread.

[GINA]

Its the first race in China, and my team is trying not to be the last one .So, anyone can tell how to shorter the acceleration time for 75 meters ?

[Tropenk]

There are just so many ways to get your car faster... Starting from "increase the power of the engine", "get a proper traction and launch control" to "reduce shift time" or just very simple "take care of your tyres", just to name a few. You can't expect an answer to such a question. Because there exists neither a perfect solution nor a simple one. Try to ask about a certain problem or method to get your car faster will eventually help.

[oz_olly]

The most simple way to look at it is if F=ma then a=F/m. So to increase a you can either increase F or decrease m. There is a huge number of different functional ways to modify F and m.

[TMichaels]

Develop a flux capacitor and arrive at the finish line before you cross the starting line...you only have to be able to get to 88mph before reaching the finish line..wait...that would make a good acceleration time anyway http://fsae.com/groupee_common/emoticons/icon_smile.gif

Regards,

Tobias

[MH]

Why so difficult?? You can also just measure out 75 YARDS http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

Miki Hegedus
Delft University of Technology 2001-2008

[JVC]

I would suggest 75 feet http://fsae.com/groupee_common/emoticons/icon_razz.gif

[GINA]

http://fsae.com/groupee_common/emoticons/icon_smile.gif
Originally posted by Tropenk:
There are just so many ways to get your car faster... Starting from "increase the power of the engine", "get a proper traction and launch control" to "reduce shift time" or just very simple "take care of your tyres", just to name a few. You can't expect an answer to such a question. Because there exists neither a perfect solution nor a simple one. Try to ask about a certain problem or method to get your car faster will eventually help.

[Wesley]

Originally posted by Mikey Antonakakis:
But the intake isn't within the plane...

I'm tired of these intakes on this mother$*(#in' plane!

I know shift times are a pretty big killer of accel times. Our button actuated pneumatic systems in '05-'09 left a lot up to the driver. I always fat fingered them and had half-second shift times. I wanted to set up a timer circuit that would only engage the relay for x amount of time no matter how long you held the button, but magic smoke and I are not friends.

[Gruntguru]

Originally posted by oz_olly:
The most simple way to look at it is if F=ma then a=F/m. So to increase a you can either increase F or decrease m. There is a huge number of different functional ways to modify F and m. Probably even more important: s = 1/2at^2 and Power = F x V.
Assume a traction limit and weight on the driven wheels to give F for the first (traction limited) phase of the run. When V has increased to the point where F x V = your engine Power, you are no longer "Traction Limited". The rest of the run is "Power Limited". Make a spreadsheet with columns for F, a, v, s and t. When the s column gets to 75 yards, the t column shows the elapsed time. Now you can play with different levels of power, mass, traction etc. The results will surprise you and you will quickly discover what is important. Hint, one of the variables is VERY important and the others decrease in importance very rapidly.

[Gruntguru]

Originally posted by Wesley:
I know shift times are a pretty big killer of accel times. How big? eg if the 1-2 shift takes an extra 1/2 sec, how much does the et increase?

[VFR750R]

Originally posted by Gruntguru:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Wesley:
I know shift times are a pretty big killer of accel times. How big? eg if the 1-2 shift takes an extra 1/2 sec, how much does the et increase? </div></BLOCKQUOTE>

Depends when you shift, and how fast you're going when you shift. The faster you are going when you shift, the less time is lost because you're already traveling fast during the lapse in accel. Should be pretty easy to make an excel spreadsheet and see what the time loss would be.

[Mikey Antonakakis]

I believe someone at Auburn wrote a pretty good SAE paper on shift times vs final drive ratio.

[JasperC]

Originally posted by Gruntguru:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Wesley:
I know shift times are a pretty big killer of accel times. How big? eg if the 1-2 shift takes an extra 1/2 sec, how much does the et increase? </div></BLOCKQUOTE>
Well, you just explained how to make a simple simulation of an acceleration run. All you need to do is link car speed to RPM, determine at which RPM you need to shift and say F=0 while shifting. http://fsae.com/groupee_common/emoticons/icon_wink.gif

This might get a bit tricky to do in an Excel sheet but the Matlab/Java/... code for this is pretty simple. And useful too, since you'll be able to determine your final drive ratio, gear ratios (if you have different sets of gears available) as well as the requirements for shifting time.

Then the next step is to link RPM to fuel consumption and you'll be able to determine shifting points for the endurance, which will be different because you're running less fuel efficient at the higher RPM's (this is the case for our single cylinder anyway). http://fsae.com/groupee_common/emoticons/icon_smile.gif

Best regards,
Jasper Coosemans

Chief Drivetrain 2009-2010
DUT Racing Team
Delft University of Technology

[Gruntguru]

Originally posted by VFR750R:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Gruntguru:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Wesley:
I know shift times are a pretty big killer of accel times. How big? eg if the 1-2 shift takes an extra 1/2 sec, how much does the et increase? </div></BLOCKQUOTE>

Depends when you shift, and how fast you're going when you shift. The faster you are going when you shift, the less time is lost because you're already traveling fast during the lapse in accel. Should be pretty easy to make an excel spreadsheet and see what the time loss would be. </div></BLOCKQUOTE>Yes. For example, for a typical car capable of 4.1 second acceleration times and shifting from first gear at a velocity of 20 m/s, the difference in elapsed time for a 0.5s shift versus 0s shift is about 0.2 seconds - so less than half of the shift time.

[Gruntguru]

Originally posted by JasperC:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Gruntguru:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Wesley:
I know shift times are a pretty big killer of accel times. How big? eg if the 1-2 shift takes an extra 1/2 sec, how much does the et increase? </div></BLOCKQUOTE>
Well, you just explained how to make a simple simulation of an acceleration run. All you need to do is link car speed to RPM, determine at which RPM you need to shift and say F=0 while shifting. http://fsae.com/groupee_common/emoticons/icon_wink.gif

This might get a bit tricky to do in an Excel sheet but the Matlab/Java/... code for this is pretty simple. And useful too, since you'll be able to determine your final drive ratio, gear ratios (if you have different sets of gears available) as well as the requirements for shifting time.

Then the next step is to link RPM to fuel consumption and you'll be able to determine shifting points for the endurance, which will be different because you're running less fuel efficient at the higher RPM's (this is the case for our single cylinder anyway). http://fsae.com/groupee_common/emoticons/icon_smile.gif

Best regards,
Jasper Coosemans

Chief Drivetrain 2009-2010
DUT Racing Team
Delft University of Technology </div></BLOCKQUOTE>The simplest way to determine shift points is to graph the "Thrust Curve" (force available at the tyre) for each gear and shift at the intersection of successive curves. This technique neglects rotational inertia of components upstream of the gearbox (mostly engine) but is still pretty accurate.