End of the day, north of Fargo
Today was a great day. We ran for over 9 hours with only 4 minutes on the side of the road for a required driver swap. Because the distance between Sioux Falls and Fargo was too great to complete in under 6 hours and our drivers are only allowed to drive for a max of 6 hrs a day, we swapped drivers at a safe location outside of town. Paula drove this afternoon and completed the day at 6:03pm just north of Grand Forks. With pasta on the stove, work completed on the vehicle, and the tent already set up, tonight hopefully we will get a decent amount of sleep and be ready to race tomorrow.
Posted by Jeff Ferman at 9:15 PM | Permalink |
21 comments
21 Comments:
Where are the Christian Scientists
Principia has a radio-cast NOW!
http://www.prin.edu/public/index.pl/radio_podcast
They are in Grand Forks.
jay
LSA '72
Well done, Momentum!
There was a large, fun, and enthusiastic group of team parents, former team parents, former team members, and other supporters in Sioux Falls to cheer the Michigan team as they left this morning at 9 a.m. It was fun to see so many maize & blue shirts!
We're all so proud of how well you team members are doing and what a credit you are to your program and your school. In Sioux Falls you were a class act in the way you responded to questions from passersby and the media, helped each other and the other teams, and demonstrated a high level of professionalism.
Best of luck with the last stages of the race, which we will continue to follow via computer. Go BLUE!
Steve & Donna Adams
This is actually in response to Maggie from a couple posts down, regarding our nerd-crush on Hans Tholstrup.
One of the finest solar car images ever.
Good luck tomorrow, Blue, and say yah to Canada, eh?
Oh I just remembered this, here's an image of special importance to UM fans...it's a package of sunflower seeds:
http://tinyurl.com/579bvj
According to Google Maps, Michigan ended 45 minutes away from Principia. I've also been told that Principia stopped early. If Prinicpia stopped at 5:45, then Michigan should have added about 30 minutes to their lead today, increasing their total lead to about 50 minutes. Go Blue!
MapQuest says Grafton, ND is about 120 miles from Winnipeg. So Michigan should reach Winnipeg around 10 or 11 o'clock.
Somewhere on the road between Sioux Falls and Fargo, they passed the halfway point. They have something like 4 and a half days to finish the 2nd half of the race.
I feel like we've been neglecting the other teams. Anyone know Fargo times for Bochum, Waterloo, Minnesota, etc? Have the slower teams reached Fargo yet?
Ask (and scan some other blogs) and ye shall receive. Missouri S&T reports they made Fargo at 5:45 and decided to spend the night there. They say Waterloo, FH Bochum, Minnesota, and Calgary, in that order, preceded them. Iowa State, Red River, and Arizona came in after.
Apparently, S&T, Waterloo, Bochum, Minnesota, and Calgary had been traveling in a pack, switching positions back and forth as various glitches, and clouds appeared. Then Missouri had a serious problem and lost telemetry. The result of that and cloudy weather is that they don't think they will have a full charge to start the run to Winnipeg.
Minnesota reports they had a good day racing and camped 40 miles south of Grand Forks. They think Bochum, Waterloo, and Calgary are somewhere near them. They expect to make Winnipeg today easily.
And they say the popping sounds from before were fuses blowing because their shutdown procedure wasn't working properly. So they know what that problem is, and it's not serious.
about the border crossing .. a note from the Calgary blog .. "If we sail through customs, our travel clock keeps ticking: if they decide to inspect all of our vehicles, the clock stops, but we have to cover the car with a tarp to avoid charging of the array. "
We're in Canada!
> And they say the popping sounds from before were fuses blowing because their shutdown procedure wasn't working properly.
> So they know what that problem is, and it's not serious.
Well, I would say that anytime you're blowing fuses, that is very serious. A fuse acts as a last-ditch preventer of large-scale electrical mayhem/fire, and it's fully possible the fuse is defective itself, or that the same engineering geniuses who couldn't get the shutdown to work correctly also oversized the fuse. So you really can't depend on a fuse to save your butt, and you should be really worried if you're blowing them at all...
Hopefully they have it worked out and aren't just replacing the fuses everytime the car shuts down!
Good to see Michigan is picking up some more time. :)
-Rbt
1.) Who says they're not worried about the fuses.
2.) Alleged over-sized fuses vs. undersized braking systems... to each his own.
Well, the brake system is *similar* in sizing to that used on:
'01 M-Pulse
'03 SpectrUM
'05 MomentUM
So, that's really not the issue. I think Garrick was proposing the issue was due to running on worn-out pads, which is something that people do all the time in their real cars. The only difference is now you don't have the nice properties of the pad materials for thermal resistance, but instead the steel backing.
This is fine for normal driving for a period of time, and should be ok thermally for several emergency stops. Of course, if you had to emergency brake under those circumstances you would let the pads cool before continuing... but probably if you had to emergency brake, something else more dramatic is going on.
In order for a brake system to pass regulations, you need to be able to apply enough force to almost lock the wheel. Of course, the ideal braking modality is not a locked wheel but at maximum static mu (i.e. right before the wheel locks). Worn-out pads should continue to support these characteristics...
-Rbt
Morris at 11 AM.
So 10 AM race time? That's pretty good - 40 mi from Winnipeg!
At 75 & Maple Leaf 100 as of 10:55 AM.
Robert is correct, as to my knowledge the issue was worn out pads rather than broken, undersized, or otherwise seriously defective brakes (again this is pending official confirmation from the team). The brakes on Continuum are plenty strong enough to lock the wheels (and the road outside the workshop has the skid marks to prove it). Ironically, larger brakes would be heavier and thus make the car stop slower, because, as Robert alluded to, your stopping power is limited not by the size of your brakes but by the max friction coefficient of your tires (every solar car uses either the same or essentially the same tires).
In a case of worn pads, you could say, reasonably, "these brakes will be capable of stopping the car just as quickly as ever in an emergency, and, in the worst case, will damage themselves and need more significant repair after such a situation - but either way, as soon as we stop to fix the brakes we're done for the day, so let's go on a bit farther until we find a nice safe spot to stop and set up shop where we can do the job right and don't have to worry about getting sideswiped by rush hour traffic. As an added measure, we'll drive slow and not use the mech brakes unless absolutely necessary to avoid putting any more stress on them." Just my theory of what may have been going through the team's head, it's probably how I'd approach it. Of course the observers are by necessity going to be quite conservative about these things, so from that perspective a reaction of "Oh my god the brakes are making nasty noises, clearly these kids are trying to kill themselves" is understandable, and a penalty from that perspective may be fair.
I sincerely hope Minnesota was able to cure their fuse ills - sounds like some sort of short across the array when they shut off, which can, pretty easily, fry your whole electrical system. More troubling, it can set your whole car on fire - a carbon fiber and lithium battery fire is hugely dangerous, as evidenced by the 2005 Aurora car, which burned so completely they don't even know exactly what happened, because nothing left was big enough to investigate (some parts literally melted into the road). I hope things are worked out like they report, as I'd like to see them competitive and in the hunt for a good place.
A bit more brake-blogging:
I should mention that it's unclear how many of Continuum's brakes were worn - the car, unlike many solar cars, has hydraulic brakes on all three wheels, plus a regenerative brake on the motor. The regenerative brake is fully capable of stopping the car (albeit not as quickly), and won't fail unless the motor controller fails. The most likely wheel to suffer brake wear first is the front, which takes the most force, however between regenerative braking and the brakes on the two rear wheels Continuum could still stop in a hurry, especially if the speed is already pretty low. So there is a fair amount of redundancy in the system to keep the driver safe.
Congratulations on your progress so far! (though it's a bit unfortunate about the penalties...a bit too severe IMO if you were in fact able to lock the wheels on dry asphault with the brakes you had on)
Btw, thanks to TC for the kind words about the '05 and '07 aero body : ) I've been pretty busy and haven't really gone through the blog intensely until now...so I just saw that post. But I must say that, wrt the '07-08 team, I only helped a little in giving Continuum some ideas, so the credit should go to Garrick and the '07 aero team for any aero-related successes in this race!
- Skip
A lot of the credit for Continuum (especially the canopy) also goes to CJ Rose, who's currently doing naval architecture for one of the oil companies down in Texas. And a lot of other individuals helped as well.
Of course, I learned just about everything about solar car aero from Skip, so he's not entirely blameless...
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