pneumatic gear shifting(clutchless) [Archive]

crossfield

05-30-2006, 01:36 AM

Originally posted by SBehn:
I wouldn't say that it is necessarily a lot faster but the driver will feel more confident if he only has to press buttons for example. Thats really important because honestly a lot of FSAE drivers aren't trained a alot http://fsae.com/groupee_common/emoticons/icon_smile.gif

Greetings from Germany

I am a lot worried about the leakage in the system.... Is it like as we go on using the shifter the pressure inside the cylinder goes on reducing? Or would it remain the same?
What amount of strokes u can get once we fill up the cylinder? (a cylinder with avg capacity)

crossfield

05-30-2006, 02:01 AM

Originally posted by jayhawk_electrical:
We have run a pneumatic shifter since 1997 or 1998. It has had its good years and bad years. We run clutchless upshifts and pneumatic clutch on downshifts. The shift time (rpm high to low) for the 2005 car was something like 250ms but with a different control system I dropped the shift time to 140ms

Well guys please could u send some photographs of carts which have been doing well with pneumatic shifts... Since we are starting from the scratch....

BStoney

05-30-2006, 05:12 AM

www.mcmastercarr.com (http://www.mcmastercarr.com) - catalogue page 922.

Think paintball CO2 cylinder. Many teams are running either CO2 or compressed air.

It is really a very simple setup with basic +12V DC electronics knowledge... reference a basic circuit analysis book for aid in understanding this, or grab an EE

olsen5

05-30-2006, 06:49 AM

We ran a complete mechanical linkage paddle shifter with a calibrated spark cut this year at competition. With a little driver training we had the spark cut down to 150 ms, so achieving the complete shift in less than that. Best part is we don't have to worry about popping an air line or leaking hydraulic fluid. You just have to take some time setting up your advantage properly for actuation.

Chris Boyden

05-30-2006, 07:43 AM

About RPM we are likely to cut the ignition when we want to change the gear, either upwards or downwards. All suggestions are welcome..

Careful with cutting ignition on both directions....do you really want to cut ignition on downshift? if anything, an automatic throttle blip is in order, which would probably be illegal.

Tim H. Heinemann

05-30-2006, 08:16 AM

if anything, an automatic throttle blip is in order, which would probably be illegal.

The most annoying part of the no-E-gas-rule is the fact that double-clutch games such as with BMW's SMG, Ferrari F1-street geaboxes etc. aren't allowed either......what a pity! http://fsae.com/groupee_common/emoticons/icon_wink.gif

Tim

Erich Ohlde

05-30-2006, 10:07 AM

cutting ignition on downshift is a bad idea. on a downshift you want the engine to speed up in between gears for rev matching, that is why our drivers blip the throttle when they hit the downshift. Also upshift ignition cut is meant to unload the gears so that you can get out of whatever gear and into the next, engine goes from acceleration to deceleration. when you are already decelerating you want to accelerate the motor(blip the throttle), not decelerate it more.

olsen5

05-30-2006, 11:14 AM

We only cut on upshift, gives a shift without lift, downshift the driver does a quick throttle blip before the clutch starts to engage again. Sorry I left that out above, assumed everyone would have already known that cutting on downshift is not the right way to do things.

crossfield

05-31-2006, 02:06 AM

Guys, I got the theory behind whatever u said... But in case of manual shifting dont u clutch the vehicle irrespective of u are shifting to lower or higher gears? Of course not to the optimum level when u are shifting it to lower gears.. I think its the same with the ignition cut also.. The whole idea behind is to cut off the engine whenever u want to shit the gears.. What u people think of this? I'm seriously in need of interaction........

Bryan Hagenauer

05-31-2006, 03:56 AM

No. As was already stated, you do not want to cut the ignition on downshift. You need to increase the rpm to line up the next gear, hence a blip of the throttle.

Along the same lines, you do not need to use the clutch. Clutch on upshift is a waste of time since your ignition cut already unloaded the gearbox, and clutch on downshift isn't really necessary although its probably nice for the engine.

Erich Ohlde

05-31-2006, 09:16 AM

Originally posted by crossfield:
Guys, I got the theory behind whatever u said... But in case of manual shifting dont u clutch the vehicle irrespective of u are shifting to lower or higher gears? Of course not to the optimum level when u are shifting it to lower gears.. I think its the same with the ignition cut also.. The whole idea behind is to cut off the engine whenever u want to shit the gears.. What u people think of this? I'm seriously in need of interaction........

I'm not quite getting your question. But is sounds like you are confusing a street car manual tranny that uses synchros with the sequential tranny that uses dog rings to engage the gears.

Chuck Maddocks

05-31-2006, 10:31 AM

does anyone use solenoids? i haven't really looked at what forces are required, but it seems like using a solinoid or two might be simplier than a pneumatic system and possible lighter. has this been tried before?

Johan_siriusracing

05-31-2006, 11:19 AM

Originally posted by Chuck Maddocks:
does anyone use solenoids? i haven't really looked at what forces are required, but it seems like using a solinoid or two might be simplier than a pneumatic system and possible lighter. has this been tried before?

We are using a solenoid, and we have been using it for 2years and it works perfectly!

Btw our shifting scheme is to cut ignition when upshifting, but to automatically clutch when downshifting.

You can see the solenoid on:
http://bart.sm.luth.se/~ojoeri-1/formulabilder/pan6.jpg

Erich Ohlde

05-31-2006, 12:03 PM

We have looked into electronic shifting, most of the solenoids/actuators we have seen are heavy and require a lot of power. The pneumatic system works well for us and isn't very heavy.

Marshall Grice

05-31-2006, 03:24 PM

We have looked into electronic shifting, most of the solenoids/actuators we have seen are heavy and require a lot of power. The pneumatic system works well for us and isn't very heavy.

yeah, what he said.

Erich Ohlde

05-31-2006, 03:45 PM

Originally posted by Marshall Grice:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> We have looked into electronic shifting, most of the solenoids/actuators we have seen are heavy and require a lot of power. The pneumatic system works well for us and isn't very heavy.

yeah, what he said. </div></BLOCKQUOTE>

Solid

Dan G

05-31-2006, 04:55 PM

Last year I talked with some of the Rutgers guys about their electronic shift mechanism...

<A HREF="http://evilallianceracing.com/ipw-web/gallery/FSAE05/IMG_1554" TARGET=_blank>http://evilallianceracing.com/ipw-web/gallery/FSAE05/IMG_1554

http://evilallianceracing.com/ipw-web/gallery/albums/FSAE05/IMG_1554.sized.jpg </A>

Just a standard RC electric motor. I don't remember if it was acting through a gear reduction or just directly on the shifter shaft. From the looks of the housing they probably used a cordless drill planetary or something similar. I'd imagine the controls were just reversing polarity to a 12V input. As long as the driver didn't hold the shift levers down that kind of burst loading and voltage shouldn't be a problem. Seems to be a pretty decent solution to me!

Garlic

05-31-2006, 07:21 PM

That looks veerrrryyy ssslllooowww to me.

If I don't know how fast it is, and I don't know what problem it solves, then it doesn't seem like a solution at all, much less a decent one!

But of course, the people that built it probably have more useful info.

Chris Boyden

06-01-2006, 08:52 AM

Garlic,

That kind of comment stinks even from here,
try a breath mint please.

If you look at the numbers, you might be singing a different tune.

I've got a cheap 18V skil power drill with a
planetary drive, 700 rpm output.
It takes approximately 30 in-lbf to turn the shift lever +-15 degrees. 15 degrees ~ 0.262 radians. 700 rpm ~ 11.67 rps ~1.86 radians/s.
0.262 radians / 1.86 radians/s = 140 ms.

Does that seem slow to you? Seems pretty good to me. A rare earth magnet astro cobalt drive dc motor spinning the planetary drive faster would make it even better....probably get it down to about 90 ms including ignition cut.

A couple of limit switches, one at each end of the travel would prevent the driver from over loading/driving the mechanism.

Marshall Grice

06-01-2006, 09:23 AM

couple thoughts.

-that setup isn't "on the market".
-we don't have 18V to run a drill motor.
-electric motors make no torque at max speed. and typically max torque at 0 rpm.
-electric motors are heavy.
-assuming the motor is 100% efficent it would draw ~17 amps, not including any inductive effects.
-trying to get a motor to turn on and off in ~90ms is going to take way more current then that.
-limit switches are failure prone.

Chris Boyden

06-01-2006, 01:06 PM

-that setup isn't "on the market".

Are we "off the shelf" engineers or is this about designing a product? Who cares if it isn't on the market?

-we don't have 18V to run a drill motor.

That's obvious....12Volts is common. I never said you have to use "this" drill. It makes for a decent example. Current would go up with a 12 volt motor for equivalent power.

-electric motors make no torque at max speed. and typically max torque at 0 rpm.

True, but with the proper gearing, you would probably bias the motor speed/torque somewhere in the middle of those extremes. Drill motor/planetary gear sets put out ~300 in-lbf
of torque. Motorcycle gear boxes only require
a tenth of that capacity at the shift lever.
Current requirements go down as torque goes down.

-electric motors are heavy.

Some of the drills are ~4 lbs with the battery, which is already on the car cutting probably 2 pounds. How heavy is heavy? more quantitative and less qualitative
pneumatic weight vs. motor vs. solenoid etc...

-assuming the motor is 100% efficent it would draw ~17 amps, not including any inductive effects.

Where did 17 amps come from?
If 17 amps....how often and for how long?
RMS current taking into account the surge and steady state current is a better indicator of how the battery would be effected.

-trying to get a motor to turn on and off in ~90ms is going to take way more current then that.

How much more? inrush is typically 10 times operating current at a given load.
The resistor inductor circuit between the battery and the motor would determine inrush, rise time etc...The mechanical rise time would dominate the response time of the motor.
It takes no current to turn the motor off.
An H bridge motor driver in braking mode
doesn't source current, it can consume it.
This thing wouldn't be constantly running anyway....it's a duty cycle issue.
Even if you shifted all six gears in a 6 sec accel run with a 600msec accumulated shift time, you'd be running the motor at a 10% duty cycle. So take the RMS current and multiply times 10% to get an estimated constant load.

-limit switches are failure prone.
hall effect switches are solid state

Marshall Grice

06-01-2006, 01:52 PM

17amps comes from your calcs. torque*rpm=power then ohms law. So i estimate at least 17 amps steady state current. using your rule that would be 170 amps inrush. We all know it won't flow 170 amps but it will certainly cause a voltage spike/dip which can easily cause problems with other electircal systems on the car. our 6 watt pnumatic solenoids cause enough problems. Using your 10% DC that puts the current back to 17 amps.

using a straight planetary gear set with out fancy clutches/mechanisims you need to reverse the motor to reset the shift lever. so you don't have to expend energy to turn it off but you do need to reset. granted the reset time is a smaller concern but what sort of dead time do you want between shifts?

pneumatic system weighs roughly 3lbs. my point isn't that the electric is going to weigh more, but don't think you're going to save weight by doing electric.

I agree that the mechanical rise time is going to dominate the overall response of the system. It may be an electrical system but F=MA still rules. While it may only take 30in-lbs to activate a shift designing for a max of 30 in-lbs will not yield sufficiently fast shift times. We run 70+ in-lbs with our pneumatic system. We see gear change times ~45ms with overall shift times around ~125ms.

allow me to clarify, adjusting limit switches is failure prone.

Garlic

06-01-2006, 01:58 PM

Yes, 140ms for the motor to shift the lever does seem very slow. I am confident that you need a shift time much fast than that to beat a decently trained driver.

Kyle Walther

06-01-2006, 02:44 PM

Originally posted by Johan_siriusracing:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Chuck Maddocks:
does anyone use solenoids? i haven't really looked at what forces are required, but it seems like using a solinoid or two might be simplier than a pneumatic system and possible lighter. has this been tried before?

We are using a solenoid, and we have been using it for 2years and it works perfectly!

Btw our shifting scheme is to cut ignition when upshifting, but to automatically clutch when downshifting.

</div></BLOCKQUOTE>

is this the system you use? http://www.pingelonline.com/eshifter_universal.htm

also, does any one have the weight for a mechanical system and any shift times(good and bad driver).

olsen5

06-01-2006, 03:50 PM

well, our mechanical system, including both cables, paddles/brackets, and the ignition cut stuff comes to about 1.5 pounds. We have been playing with our cut times and have them now down to 120 ms. I think we still have quite a bit of room to improve that with more driving time. We started the first cut times at around 160 ms and have been bringing them down from there as the drivers get more comfortable.

Garlic

06-01-2006, 04:15 PM

The problem with 'shift times' is nobody measures them the same way. I can't take any stock in what anybody says thier shift times are. It can vary so much, depending on how you define it, and also how you measure it. And if you are looking at such a short time period, sensor response times and logging rates become very critical.

The only real way to know is having the exact same measurements and measurement tools, and a detailed way of defining the shift time. Which will NEVER happen unless it's the same team, basically.

So... you gotta do your own testing if you really want to know what's best.

Kyle Walther

06-01-2006, 06:00 PM

how would you measure the "shift time"?
we've been measuring it based on RPM drop to RPM pick up.

Erich Ohlde

06-01-2006, 06:53 PM

We measure it the exact same way.

crossfield

06-02-2006, 12:15 AM

Ok, one thing I am not understanding is that we cannot make a paddle asembly without clutch? We need clutch to get the initial momentum. ie, in the 1st gearatleast. Or can we do it without a clutch? Coz we wanted only acclerator and brake in the paddle system..

crossfield

06-02-2006, 01:18 AM

Ohhhhhhhh! I am not too much into electrical. Frankly speaking i am not able to undrestand the electrical stuff u are talking about..err.. sorry!!! Any stuff regarding pneumatics are really welcome..
Jus I will try to find the feasibility of a electronic shift versus a pneumatic shift or vice versa and will be back to u guys...

BStoney

06-02-2006, 04:35 AM

Originally posted by crossfield:
Ok, one thing I am not understanding is that we cannot make a paddle asembly without clutch?... Coz we wanted only acclerator and brake in the paddle system..

I assume you are talking about a pedal assembly when you say paddle?

olsen5

06-02-2006, 04:52 AM

Our spark cut is calibrated through our ECU. It is independent of how long the switch is engaged. I agree that no two teams will measure their shift times the same.

As for Crossfield, when I say paddles I mean the assembly right behind our steering wheel that we are using to engage/disengage clutch, and to shift gears up/down. In our foot pedal assembly we only have 2, brakes and accelerator.

crossfield

06-02-2006, 04:53 AM

yeah pedal not paddle.. Im sorry...

olsen5

06-02-2006, 05:46 AM

nothing to apologize for, I just hope all this is helping you get your system figured out

Marshall Grice

06-02-2006, 09:37 AM

you still need a clutch but it doesn't need to be activated for shifting. only for starting and stopping. we use a hand clutch.

crossfield

06-03-2006, 12:28 AM

Thank you very much... This info has helped me a lot to start building the system as such.. I was really confused as to how can a system exist without clutch. U people know that we have started from scratch as I mentioned earlier.. This forum is really cool.. Hope I go on getting messages which would be useful further....

olsen5

06-05-2006, 04:54 AM

crossfield, check your private messages

crossfield

06-05-2006, 06:02 AM

Now that I have been discussing things i have a strong doubt that we should go for a electric or a pneumatic shift...

Tim.Wright

06-05-2006, 10:22 PM

Hey guys,

We ran an electric shifter last year in Victoria. Cordless drill jobbie. drew 15-20 amps and reset our wideband sensor box every shift, as well as dimming half the city lights in Melbourne I think. We had our igntion cut set at 600ms so the thing would settle properly. Check out our battery voltage log from our (short) enduro

http://www.student.curtin.edu.au/~12419520/yessssShifter.jpg

The motor is almost permanently running at stall (moves only 15deg) so there is plenty of torque (enough to tear our assembly of it's shaft the night before the enduro cool ey?) but uses heaps of current.

All that said I don't think it is impossible to come up with a neat electrical solution, just requires careful selection of efficient motors (no drill motors) and correctly sized gear boxes. Ours was obviously too large a reduction, (too much torque, too slow).

Enjoy

Timbo

adrial

06-06-2006, 04:44 PM

Originally posted by Dan G:
Last year I talked with some of the Rutgers guys about their electronic shift mechanism...

[URL=http://evilallianceracing.com/ipw-web/gallery/FSAE05/IMG_1554]http://evilallianceracing.com/ipw-web/gallery/FSAE05/IMG_1554

Just a standard RC electric motor. I don't remember if it was acting through a gear reduction or just directly on the shifter shaft. From the looks of the housing they probably used a cordless drill planetary or something similar. I'd imagine the controls were just reversing polarity to a 12V input. As long as the driver didn't hold the shift levers down that kind of burst loading and voltage shouldn't be a problem. Seems to be a pretty decent solution to me!

I am not the electrical/controls guy...not even on the team anymore for that matter...but that shifter was used in '03-'05.

It works well, but is very finicky...everything needs to be just right. For the '05 comp we had no functional shifter...needless to say, that left us more than a little displeased with the system.

It shifted hard/fast enough to break the tires lose on upshifts...we detuned it from there to help driveability. No issues with draining the battery...then again we dont shift very often. We drove almost all of endurance in 2nd gear... 4:1 final drive ratio / yamaha R6.

Since then we have gone to a straight wheel mounted mechanical paddle shift on a push/pull cable (moves with the steering wheel)...very happy with the change...clutchless upshifts and downshifts are a breeze...system is 100% reliable...which is the most important thing in a shifter.

crossfield

06-07-2006, 08:06 AM

when u talk 600ms is it meter second?

crossfield

06-07-2006, 08:08 AM

Does it mean that no matter we use any kind of system, we need to tune up the engine accordingly?

Marshall Grice

06-07-2006, 08:44 AM

600ms=600 milliseconds or .6 seconds.

crossfield

08-14-2006, 01:25 AM

Originally posted by Timo:
Hey guys,

We ran an electric shifter last year in Victoria. Cordless drill jobbie. drew 15-20 amps and reset our wideband sensor box every shift, as well as dimming half the city lights in Melbourne I think. We had our igntion cut set at 600ms so the thing would settle properly. Check out our battery voltage log from our (short) enduro

http://www.student.curtin.edu.au/~12419520/yessssShifter.jpg

The motor is almost permanently running at stall (moves only 15deg) so there is plenty of torque (enough to tear our assembly of it's shaft the night before the enduro cool ey?) but uses heaps of current.

All that said I don't think it is impossible to come up with a neat electrical solution, just requires careful selection of efficient motors (no drill motors) and correctly sized gear boxes. Ours was obviously too large a reduction, (too much torque, too slow).

Enjoy

Timbo

Hi! Since we decided to go for a electric shift.. I would like to know whether the motor was directly coupled to the shift spindle or was it connected indirectly in any other way.. and since we are using MOTEC this time (not using the stock one) does it really help to sort out the issue? Is he electric system reliable?

Tim.Wright

08-14-2006, 09:10 PM

No, the system wasn't really reliable for us, but I'll tell you how we set it up anyway. I think an electric system could work, just not the way we did it.

The actuator was a right angle cordless drill which comprised of a 16V motor, a bevel gear set for the right angle, and a planetary gearset to the output shaft via a heavy steel coupling (I dont know the ratio of the gearbox unfortunately).

The switching was done with a series of relays configured in a H-bridge with an extra relay to avoid a short circuit condition when both shift buttons were pressed. Finally the H bridge was switched by two buttons on the steering wheel.

The problems we had which finally caused us to throw the whole thing in the bin was that the motor is used under pretty harsh conditions as a shifter. By this I mean that it is almost permanently run at stall which produces large torques (good for shifting fast, but not so good for the gearset). The bearings inside the bevel gearbox eventually flogged themselves out and the gears sheared their teeth off because of misalignment.

This happened because we did no analysis of the internal forces in the drive assembly. So if you carefully select your motor and gearbox, I think you could make a good system.

Having said that we are trialling a Pneumatic system this year.

Tim

crossfield

08-18-2006, 08:10 AM

ok.. thats fine.. But atleast can u give me a vague idea of ur relay set up?

formula_wally

08-18-2006, 09:26 AM

IM not to intrigued in using an electrical motor to drive the shifts. We use an electronically controlled air pneumatic shift system to control the clutch and shifts. A microcontroller sends logic levle signals to our electric relay bank which distribute the proper air flow to our two singal acting clynders.

Im pitching to use it again next year, but its just mildly heavy and intrusive on the rear end packaging. If you can develop the transfer function of the clutch relay control, you should be able to use it in matlab to predict and create a really nice release rate scheme based on bit bashing into your relay.

Pick your battles though, most importantly show up with a fast car that your crew will be proud of<:

Tim.Wright

08-20-2006, 05:50 AM

Originally posted by crossfield:
ok.. thats fine.. But atleast can u give me a vague idea of ur relay set up?

Yep, the relays were configured in a H-bridge. I can't explain it in words nor do I have a schematic of it, but run a search on it and you'll find heaps of info.

With the H-bridge, it is possible to short circuit the battery when both upshift and down shift buttons are pressed. So we put in an extra relay which cut out, for example, the up-shift button when you press the down-shift button.

I can't remember exactly how we achieved this but again there will be schematics which get around this problem floating about.

You will need to use 30A automotive relays as the motor will pull a lot of juice. you need 4 SPST relays for the H-bridge plus 1 SPDT for the dead short protection, and a couple of SPST momentary switches for the shift buttons.

This will make more sense to you when you find a H-bridge schematic.

Timbo

Steve Yao

08-20-2006, 06:48 PM

F-Wally,
What happened to the sweet hydraulic-manual-paddle clutch/shifter you had in 2005?

Originally posted by formula_wally:
IM not to intrigued in using an electrical motor to drive the shifts. We use an electronically controlled air pneumatic shift system to control the clutch and shifts. A microcontroller sends logic levle signals to our electric relay bank which distribute the proper air flow to our two singal acting clynders.

Im pitching to use it again next year, but its just mildly heavy and intrusive on the rear end packaging. If you can develop the transfer function of the clutch relay control, you should be able to use it in matlab to predict and create a really nice release rate scheme based on bit bashing into your relay.

Pick your battles though, most importantly show up with a fast car that your crew will be proud of<:

formula_wally

08-20-2006, 08:34 PM

We still have drawings for the system. It was really done well. I think the machining time was under 20 hours. For those who haven't seen it, we had 3 levers on the back of the paddle that went into a centre unit on the wheel. On down shift, it grabs the clutch as well.

The hydraullic system in our 2005 car is nice, There is little effort, yet the regular amount of maintenance required to keep it primed and usable. The nice thing about it is that you can still keep your half shift to neutral, and use 1st if you really need it. The only bother is that its still hard to find when rolling back into the paddock.

Im a big geek and lover of microcontrollers, thus my reasons to want to try and elec-pneu system instead. I think having programmed upshifts, and bit bashed clutch control release will do us better that what un-experienced Me will do with a manual clutch on the accel event.

Marshall Grice

08-22-2006, 09:49 AM

I'm suprised you're still using relays, especially if you plan to do a high speed switching algorithm.

Tim.Wright

08-22-2006, 09:14 PM

Originally posted by Marshall Grice:
I'm suprised you're still using relays, especially if you plan to do a high speed switching algorithm.

The relay system we used was a throw together the night before the enduro and replaced a fast switching mosfet H-bridge which caught fire twice.

Either way both systems are in the bin now

Marshall Grice

08-23-2006, 08:39 AM

well nevermind then...

lux

08-25-2006, 05:11 AM

This year we use also a electrical gear shift system. The benefits are lighter, cheaper, faster and safer as a pneumatic system.
As actoator we use the motor-gear combination from a electrical drill machine. The anvantage is the price (you can use the cheaperst drill machine you found about 15€) and the integrated slipping clutch. If you use only a dc motor for change you have the problem that in case of block the motor produce a shortcut. (you can see this on the diagram from Timo) With the slipping clutch the motor can rotate again and you have also a force on the shift pedal. For the direction of rotation we use a self developed control unit but you can also two relais with two-way contacts. Weight for the total system is under 700g and you need less components as on a pneumatic system.

regards from Graz, austria
Lu

crossfield

08-28-2006, 03:20 AM

yeah,.. But i couldnt get the word "slipping clutch"....

Bandit

09-06-2006, 04:58 PM

700 grams? I doubt that. Still maybe slightly lighter than a good pneumatic system. Maybe not.

faster. no.

cheaper? probably in component cost, not labor, and probably less reliable regardless.

safer? This is racing first of all, its never safe. A 4500 psi air bottle sitting there doesn't make it any more hazardous for the driver going 75mph 2 inches from the ground agreed?

KU_Racing

09-07-2006, 07:32 AM

in my mind, the well designed and engineered, QC'ed, 10x safety inspected, multi-national safety organization certified 15000 psi bottle holding 4500 psi of nitrogen or whatever is not nearly as dangerous as the 14000 rpm student assembled high volume internal combustion pump, or the student fabricated and welded titanium/magnesium/aluminum/4130 space frame (sorry to all the welders.... im one too, most of us are very good), or the 0.00001 thick stainless 2 gallon tank of race gas (usually approx. 3 inches from a 1200 degree header), or the driver's feet hanging 24 inches in front of the wheel centerline, or the top of his (or her..) helmet sticking up 2 inches above the roll envelope of the frame, or the brake calipers held on by 1/4 inch bolts, or 90% of the rest of the parts on a typical FSAE entry.

Just a thought....

Superfast Matt McCoy

09-07-2006, 09:06 AM

Speak for yourself mister "make your tank out or .015 aluminum"

http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

darienphoenix

09-07-2006, 06:16 PM

Originally posted by KU_Racing:
in my mind, the well designed and engineered, QC'ed, 10x safety inspected, multi-national safety organization certified 15000 psi bottle holding 4500 psi of nitrogen or whatever is not nearly as dangerous as the 14000 rpm student assembled high volume internal combustion pump, or the student fabricated and welded titanium/magnesium/aluminum/4130 space frame (sorry to all the welders.... im one too, most of us are very good), or the 0.00001 thick stainless 2 gallon tank of race gas (usually approx. 3 inches from a 1200 degree header), or the driver's feet hanging 24 inches in front of the wheel centerline, or the top of his (or her..) helmet sticking up 2 inches above the roll envelope of the frame, or the brake calipers held on by 1/4 inch bolts, or 90% of the rest of the parts on a typical FSAE entry.

Just a thought....

Or the fire retardant suit rated for 3 seconds of inferno before 2nd degree burns, when egress time is 5 seconds? http://fsae.com/groupee_common/emoticons/icon_wink.gif

Can't remember who made the topic mentioning that, but I'm glad I'm not driving.

Bandit

09-07-2006, 09:01 PM

yeah, I dont know if anyone rembers detroit this year, the MSOE car (which i di ~1/3 the construction on) burst into flames exactly halfway through endurance,

I'll say it again, safety in a racecar, can only be to such a degree.

By the way... Did anyone else protest those useless automotive style band clamps with the commitee? Or was I the sole individual victim to thier slighting on the issue of band vs. worm gear drive fuel hose clamps? Every real racecar uses worm drive clamps.

Seriously. Back me up on this one? Is this off topic now?

Ian M

09-08-2006, 07:39 AM

Yeah, we got reamed for using worm gear in 2005 and had to find the special rolled edge ones. Problem was the rolled edge ones we found wouldn't quite tighten down tight enough, so we probably got lucky we didn't turn into a speeding fireball also. I think that rule is kind of stupid, but there are some that I find a little questionable! We got DQ'd from endurance because a little brake fluid sloshed out of our VENTED master cylinder caps. Shouldn't have filled them up or should have put a rag on top I guess! Live and learn!

Superfast Matt McCoy

09-08-2006, 08:25 AM

I don't see a problem with requiring fuel injection clamps for fuel injections lines. It's been in the rules for at least 2 years, many more i'm sure. I did, though, have to shop around for clamps that were small enough. Check NAPA. And read the rules. I've noticed a lot of stuff on other cars that don't meet the rules that they don't check for, specifically, Pneumatic shifting stuff, like lines and regulator placment.

notice my back-to-topic segway seamlesly integrated into that comment.

Erich Ohlde

09-08-2006, 11:31 AM

yeah, there were a couple of teams with off-bottle regulators. kind of illegal

Eric Mattessich

06-10-2007, 09:12 PM

Hey do you guys think something like this http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXRAX0&P=7 . Would it be able to operate the shifting mechanism? It puts out 340 in-ounce of torque... and if its true what Chris Boyden said about you only needing 15 degrees of movement then you could just do a nice gear ratio and be set. Speed @ 6V: 0.17 sec/60? for a 2.2oz piece seems like a good bet.... what do you guys think?