The Robot Dragster Project - Chapter Seven. "One half Impulse Power...."

We meet on Thursdays.

In the winter this means that I very much hope for blizzards and other inclement stuff to come any other day of the week.  This week school was cancelled on Tuesday due to an ice storm.  Thursday was good.
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Final wiring done.  We ran out of time before we could connect up the steering, it needs a little reinforcement anyway.  The remaining sessions will be testing and adding crash resistance.

This is the near final form.  Sadly, we don't get any sponsorship from 3M...somebody just brought the stickers in.

This is bench testing the control system....and a rough idea of maximum rpms once it gets up to Warp Speed.

As you can see, the theoretical top speed is scary.  I detailed two kids to work on a braking system. The theory is that we mount this high torque little gear motor with a bolted on plywood/friction tape paddle in such a fashion that when it is activated it will repetitively "bump" the drive belt.  Sort of like pumping the brakes on an icy road.  Which in fact is probably exactly where we will end up testing it.

With about 15 minutes to spare we plopped the dragster down in the hallway and powered it up.  Nothing happened, the belt spun, the wheels stood still.  This was puzzling to me, I knew it had worked a week earlier.  One of my brighter students correctly diagnosed the problem, the shaft holding the front steering wheel was binding the wheel.  Once this was freed up we were able to do several short hallway tests.  At this point we are not trying to steer it, simply give it about five seconds of power to see what the acceleration is like.

Ahead at one half impulse power, Mr. Sulu.

The lads are in fairly high spirits, as they should be.  This is a complex machine and I think it has good prospects for working well.  My assistant and I are privately estimating a top speed of 30 to 35 mph if we can get the police to block off a section of nearby roadway for us.  And if they can control it.

Also if it does not snow on the test day.  I probably should have done this project spring trimester but that would conflict with my archeology trip.

Forgotten Brewery Caves - Suds, a Fugitive and Hidden Treasure

At first I was not sure whether to include this one in the list of "forgotten" brewery caves. It has been preserved for visitors.  Heck, you can read about it on the website of the  Bruce Vento Nature Sanctuary.  But as you make your way out of downtown St. Paul you quickly realize that this is a site that has indeed been mostly forgotten.  I had to wind my way through a construction area, under a freeway bridge and then down a narrow little lane to get there.  My only fellow visitors were strangely equipped, warm clad folks who wandered around in ones and two carrying little rakes and shovels.  (They were searching for the Winter Carnival Medallion, always hidden in a public area).

Here is the cave.

This cave was used by the North Star Brewery.  The brewery got its start in 1855, oddly enough run at first not by Germans but by a Scotch/English partnership.  The initial establishment was small, only a single natural cave enlarged for ageing purposes, and two 50 by 75 foot buildings.  But the brewery grew quickly with many additions and the customary ownership changes.  It was actually built into the stone face above, with the cave(s) coming right out of the lower levels of the brewery.  By the 1880s it was producing 16,000 barrels of beer annually, and claimed to be the second biggest brewery west of Chicago.  I have read a few snippets here and there that indicate the caves had been expanded into a larger complex.  Also that it was in later years referred to as "Montana Bill's Cave".

In 1900 fire destroyed the brewery, which by now had grown to 300 by 200 feet.  The entire area then then declined into a sort of industrial wasteland.

If you look closely above you will see a smaller cave entrance to the right of the main one. There is a similar one to the left:

The reasons for this "three door" arrangement are not obvious.  The smaller flanking doors seem low enough that it is hard to imagine they were ever used as entrances....unless the grade of the land has been raised a good bit.  And this may be the case, as multilevel caves are not uncommon for the larger brewers.  Taking a peek into the main cave:

There is some serious spring water activity here, almost a foot of clear water in the floor of  the cave.  I visited on a very brisk day, so the misty effect is steam rising up from the surface.  But you can just make out the end of the cave back some 40 feet.  Actually I am pretty sure this represents a later sealing off of the cave.  You don't run a 16,000 barrel a year brewery with a storage area the size of a garage.  The two side entrances by the way appear to connect to the left and right with the main passage.  I was looking through a security gate and can't see around corners, so have no way to tell if they have also been sealed.  One does have to wonder if the water flow was less "back in the day".  It seems inconvenient.

If you look around the outside of the cave you can still make out a few traces of the old brewery buildings.

And about twenty feet to the right of this spot I saw a tell tale plume of steam coming up!

See the frost?  I assume that this is another blocked off entrance to the North Star Brewery cave complex.

Just a little more detective work located this rather well done video from the National Park Service.  You can tell they are trying to be cute here and there, but at the 4:30 mark they do briefly flash a graphic showing the four cave entrances I located, and one other that can no longer be seen.

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Addendum:  I thought that the name "Montana Bill's Cave" might relate to this odd story. William Raymond Nesbit was a jewel thief who had a falling out with some of his hoodlum bretheren.  He ended up taking the rather extreme measure of blowing up one of them with 3,500 pounds of dynamite and 7,000 pounds of black powder.  This caused quite a ruckus, breaking windows in Sioux Falls, South Dakota.....five miles away.  Nesbit was captured and convicted in 1937, but escaped from the South Dakota State Penitentiary in 1946.  Four years later he was placed on the FBI "Most Wanted List" and his picture was in the papers.  Local children recognized him as the fellow living in the North Star Brewery cave. And that is where police arrested him.

Did William from South Dakota become Bill from Montana?  Oh, I so wanted it to be so.

But it seems you can find anything on the internet, including the FBI file on the wicked Mr. Nesbit.  It turns out that he had been chatting with the local kids as they played cops and robbers, but called himself "Ray".  When the intrepid junior detectives saw the picture in the paper they thought "Ray" was Nesbit but were not sure.  I really like the part where the kids .."threw snowballs through the hole in the top of the cave to get "RAY" to come out".  With what they felt was a strong resemblance they were able to persuade the police to come and arrest Nesbit.  All very "Hardy Boys", no?

So far as I can tell, Nesbit never used the alias Montana Bill, nor is there any reason for him to be remembered by anything other than his real name or perhaps "Ray".

So, who was Montana Bill?

Anybody got the answer?

Stop and Go in Europe

We are planning a trip.  As it will be through linguistically mixed up regions it is necessary to polish up all available skills.  It has fallen to me to handle German, based on a passing familiarity.  I can manage fairly well.  In fact, once in a small village in Luxembourg I was mistaken for perhaps being Dutch and slightly tipsy, which I took as a compliment to my effective use of one year of high school German deployed enthusiastically.

So as I go here and there I pop a CD into the player and work on vocabulary.  Sometimes a word grabs my attention.

Traffic light for instance.  In German this is "ein Ampel".

I figured this must in some fashion refer to Amps the measure of electrical current, or to Andre-Marie Ampere, the pioneer of electrical theory.

But when on a walk with my spouse I mentioned this.  Alas, I too often bug her with etymological musings of this sort.  She said "Probably not", and mentioned that in French the term for traffic light is "Feu".  But she wondered if the common word "lamp" might be related to Monsieur Ampere.  L'amp sort of makes sense.

So what's the real story.  Any connections to be found?

Not really.

Ampel derives from the Latin, ampulla.  This in ancient Rome was a sort of bulbous flask that might look a bit like a traffic light.

Feu is from the Latin focus for hearth.  It more specifically means fire.  A light, or something that lights up, makes sense.

Lamp has come down more or less intact from the Latin lampas, or torch.

Poor old Ampere did not figure into any of this, but after an unhappy life (on his deathbed he supposedly left instruction that his tombstone read "Tandem Felix", which is "happy at last), he is widely remembered for his work.

Ampel interestingly has a personification, der "Ampelmannchen" or "little traffic light guy".

Ampelmannchen was specific to East Germany and is darn near the only example of Eastern Bloc design to actually catch on widely.  With reunification AM was retired for a time, but he has become a symbol of "Ostalgie", or nostalgia for East Germany.  By popular demand he has reappeared in both Eastern and Western parts of the unified Germany.

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Addendum:  The dreary "Tandem Felix" inscription reported by Wikipedia to grace the final resting place of A.M. Ampere does not appear on his tombstone.  I am not certain if this is a result of reburial (he now occupies a joint tomb with his son Jean Jacques Ampere who died almost 30 years later), or if the whole thing is one of those internet legends.  I suppose the inscription could even be on the back of the monument but there does not seem to be much room there.  Or did the executors of his estate just ignore this final wish?.....

The Robot Dragster Project - Chapter Six

These "build report" posts are not the most widely read items on my blog.  No, those all seem to involve small cute dogs or jumping carp.

But I feel a need to chronicle things of this nature because I do know that they are occasionally sought out by people contemplating student robotics projects.

My last posting may have sounded a little down beat.  A crucial component got botched and one wheel hub was fritzed up beyond repair.  On a more aggravating level, it was an avoidable error.  When you are working with no shop access, just hand tools; and when you have a less than optimal grownups to monkeys ratio, things will go wrong.  Parts that get messed up are ok....you really have to devote all extra attention to basic safety issues.

So I did something I prefer not to do.  I took the project home and fixed a couple of things for the kids.

Hey, I have a drill press, a band saw, a lathe....I can in short order make sloppy, soon to fail parts of the project into less sloppy, runs a bit longer stuff.  In order of work:

1. fixed the wheel hub.  It was a press mount that had to be fairly precise.  Fortunately I had just the right thing in aluminium, easier to finesse than the original steel part.

2. At this point curiosity took over.  I hooked the motor up to 24 volt power and stood back.

Nothing happened.

It seems the RPMs were too high and the torque too low with the existing pulley sizes. The belts just spun, the wheels stood still.  Well, nothing for it but to swap in a larger pulley.  This required cutting a slot in the deck, but has the additional advantage of raising the back of the machine so that the steering gear won't prop the front of the project up too high.

I think this was a good move.  It looks better, that's good.  It moves when powered up at 24 volts.  That's very good.  And the kids can spend more time learning new stuff rather than repetitive grinding and pounding recalcitrant metal.  Also very good.
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And things moved right along.  I just assigned tasks.  "You, finish and test the wiring on this speed controller, here's the schematics.  You and you, finish the mounting block for the steering.  You guys are working with me."

Motor mounted, battery box in place.  Note the bigger pulley on the axle.  And both wheels on securely.

The steering mechanism is on the bottom of the machine.  I am a little worried about damage.  We ran out of time just before securing the actuator into place.

Decorative touches.  Note the Axman surplus sticker on the left.  And here the kids are mounting a hood ornament.  It is called "Jerry" after some kind of video game character.

Hey, I don't have much of a budget.  My help is game but intermittent.  My work force is under age and over stimulated.  But by gosh I do have an official pit area.  Storage space...one of the things you really can't do without.

I think the dragster project is back on track, and looks as if it will work.  But I guess the second unit is not likely to happen.  We keep running into little glitches that need fixing on the main unit.  That week we lost to a snow day really hurt.

Annoying, Conspecific Houseguests

Guy Fleegman: "Sure, they're cute now, but in a second they're gonna get mean, and they're gonna get ugly somehow, and there's gonna be a million more of them." 

There really is a Galaxy Quest quote to fit almost any occasion in life.  But in this case the initial evaluation of "cute" is debatable.  

We have guests.

This is a Box Elder bug, also known as a Maple Bug.  I have always felt, based on their tiny heads and seemingly dim behaviour, that these must be about the stupidest creatures on earth.  Every fall we find them massed near the doorways of our house, trying to find a way in for the winter.  Which I guess is a fairly smart thing to be doing when you actually consider it.  They get swept, stomped, vacuumed up in bulk.

But every winter some make it in.

Mostly they are happy to just sit.  But on a warm day you always see a few come creeping out of their hiding places to sun themselves on a toasty window sill next to the radiator.  Because our autumn border patrol efforts are fairly diligent I must reluctantly conclude that they have also found a way in among the siding and insulation of our house, and that the inside of our walls contains a huge hive of the damn things.

Ick.  Brings to mind one of the movies that Galaxy Quest was sort of mocking....Aliens.

So what's really the deal with these guys?

The alternate name, Maple Bugs, explains some of it.  We have a bunch of maple trees and these little red dudes eat maple seed pods.  I figure they are none too efficient at it, as we still have lots of maple seedlings popping up in all available garden spaces.

And in the fall?  Well, according to the oh so smartypants Wikipedia:

"This is especially a problem during the cooler months, when they sometimes invade houses and other man-made structures seeking warmth or a place to overwinter. They remain inactive inside the walls (and behind siding) while the weather is cool."

And when unexpected heat comes their way?  (This must be the bug equivalent of global warming btw).

"When the heating systems revive them, some may falsely perceive it to be springtime and enter inhabited parts of the building in search of food, water, and  conspecifics."

OK, makes sense I guess.  You wake up after a long nap and food and water would be priorities.  But conspecifics?

In bug biology terms it means of the same species, or at least close enough for breeding purposes.

I get the impression that the Box Elder bugs are not all that picky.

Great, just about the ideal house guests.  Uninvited.  Gonna stay a long time.  Under foot. And inside the walls of my house having an enormous, conspecific insect Woodstock.

Digging for Romans-2013

Still frozen solid here in the States, which gets me thinking about digging in the warm spring sunshine of Northern England.

The blog name "Detritus of Empire" comes from its original incarnation, as a daily email report to the folks back home when I was away on my annual volunteer stint excavating at the site of a former Roman fort/community in England.

I am signed up again for 2013.

Last year was my fifth time over, and in some ways not the most fun one.  Dreadful, dreary weather. Rain every single day.   Heavy, slimy earth to move.  Frequent scanning of the heavens to see if the day's excavations would in fact happen.

But this is part of the experience.

As I stare out the window at chilly climes I can at least revisit gentle sunny days, and some interesting finds over the years.  Some of these are things I was reluctant to show at the time....there is an ongoing concern that outlaw metal detectors will sneak in at night and rummage through the excavations.

photo credit P. Savin

Well, the ground is frozen, even in England, and the finds I am showing today are all from areas now excavated and either backfilled or reconstructed with modern reinforcement of ancient stonework.  Plus, none of them are all that valuable, certainly nothing worth getting arrested and prosecuted at the Queen's Bench!

An assemblage of finds.  The large dark bit is a chunk of carved stone from some kind of monument or decorative work.  The grey, rectangular bit to the right is a whetstone, used then as now to sharpen metal tools.

A worked bit of stone.  Perhaps a gaming counter, but more likely a pot lid.

A nice bit of pottery.  Probably from a type of vessel that often featured a stylized face on the front.

Roman bling #1.  A small pendant with traces of enamel inset.  Evidence of women being present on the site?  But we know so little of the customs of the day, maybe men went in for ornamentation too.

Roman bling #2.  Romans did not have buttons.  So they held their clothes together with various pins.  This was a penannular brooch.  Usually the actual pin has corroded away in finds found in upper levels.

Roman bling #3.  Another brooch, one in the "bow fibular" style.  Contemporary coin for scale.  The pin would have gone across the gap in an arrangement similar to the tibia and fibula bones of the human leg...hence the name!

Wishing for spring, with warmth, sunshine and pints of ale..

The Robot Dragster Project - Chapter Five

Early on we had a discussion about brakes.  Although the primary job of a dragster is to accelerate quickly, there is the practical matter of stopping it in a fashion that allows for more than one run.

One of the motor options we looked at had electromagnetic brakes.  Past tense, I had removed them for another project.  We could have put them back on, but that motor did not get selected.

Brainstorming braking ideas the kids came up with:

Parachute, like real dragsters.
Tail hook, like jets use landing on carriers.
Ending the test course on a hill.

And of course

The "Jumpin' General Lee" option does have some appeal, but maybe we will save that for a future robotics project.

I think we can just have a long straight test course and power down the drive at about 200 feet out.
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A revealing work session.  A couple of the kids were finalists in the school geography contest. Some of the others wanted to go and cheer them on.  So I said those that wanted to should go and come back in five minutes.  Two kids stayed.

The kids who left did not come back for fifteen minutes.  The two kids who stayed buckled down and put together what looks like a workable steering system using a satellite dish linear actuator.

When the other kids wandered back things bogged down right away.  We are falling farther and farther behind and may have to concentrate on just one machine.  Even then it may not run properly.

It is really not the fault of the kids I guess.  Each year with the advanced class I try and push the limits.  How many kids can we sneak into the class?  How complex a project can we take on?  It may simply be that I have found the outer limits of what is possible....and gone beyond them.

Here is progress to date.  Sloppy work much in evidence.  Hand tools, especially in inexpert hands....

Four more sessions.  There is at least the sole consolation that this is not a class that ends in a major event as does the combat robot class.  If it does not work, well, things have been learned along the way.

Sometimes failed projects teach us the most!