From: jmuchow@SPAMMENOTcamlight.com (John Muchow)
Subject: Re: Reducing contact resistance for low volt use?
Date: Wed, 08 Jan 2003 09:47:16 GMT
Organization: MindSpring Enterprises
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X-Server-Date: 8 Jan 2003 09:49:28 GMT
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>>>>The weight of #2 wire is inconsequential in a 250lb, 9HP robot.
>>>>Several builders use even larger gauges to their battery packs (20-30
>>>>cell strings of C cells, typically) and almost all of those
>>>>connections are soldered.
>>> If the weight of it is 250 Lbs. , one can certainly put more
How so? If the weight limit is 250lbs, the builder will create a
249.5lb bot that still uses fewer cells than you'd like to see. It
goes to the weapon, armor, frame, etc.
>>> The motion control industry does quite well at arriving at point B
>>>from point A from mechanics operating within the spec. I could build
>>>such a machine, beat you, and beat you worse still, were I to *tweak*
>>>mine out the way you describe.
Ooh, a challenge perhaps? I hope so. :-)
Let's keep it simple...BattleBots rules for construction. 60-lb weight
class (we can still carry those things around if we have to). We'll
meet this summer. What city are you in?
You cannot exceed published specifications for any component. I'm
allowed to build as I want to.
Another challenge could be between my same 'bot and your tweaked bot.
>>> With a 250 gross weight, batteries could easily be the winning
>>>factor. Not how well you make a small bank work, but how well you
>>>make the balance between bank size, available space, and electrical
Perhaps, but not with a 240lb frame, weapon, armor, drive train, etc.
I agree that all these things need to be balanced out. I'm just
saying that lots of folks have tried it, and are still trying it.
Lots of folks with lots more knowledge than we have.
>>> It could easily vary from battery to battery, and from lot to lot.
>>>It could just as easily appear as if a random batch all behaved
>>>exactly the same.
Of course, as with every device or component being tested. But, the
results, if not all over the map, can be accepted as being typical.
The odds of cells from different batches being perfectly matched, but
different from any others out there (same cell from same manufacturer)
is so low as to be impossible.
>>>>I would *never* use a component in my 'bot at its rating (except for
>>>>radio receiver max Vcc). That's "proper usage" in a combat robot.
>>> So is using the right capacity bank. THEN, you can push *THAT*.
Where you and I differ is what constitutes the "right capacity". That
number can be almost anything depending on the requirements.
If I have 5lbs left for batteries, or 1/8 cubic foot available,
whatever the best battery pack I can get under 5 lbs, or smaller than
1/8 cubic feet, is the right capacity. The weight or size may be a
higher priority than the voltage drop or available torque. Cost
enters in here too.
Design requirements differ from bot to bot. There is no "correct"
design...only meeting whatever specs you have as requirements. If
your specs differ from mine, fine. That doesn't make one's design
worse than the other's...only the fight can help sort that out.
>>> Sounds silly. A minute ago, speed was king. Now, speed is
>>>sacrificed for "armor".
Perhaps it does, but only to you, not combat robot builders.
Some bots want more speed, others want torque, low voltage-drop, or
durability. Each different style (spinner, thwack-bot, rammer/pusher,
etc.) has different requirements to be successful as one of those
types. A rammer with a top speed of 5MPH is useless. But, an
effective spinner doesn't need more speed than that.
>>> The "bullet proof" panels in armored limos are made from aluminum
>>>plates. Quite light in weight, actually. Are some of your bots
>>>toting firearms? If not, how much "armor" could possibly be needed,
>>>when a simple aluminum plate stops bullets in cars, everyday?
Ahhh....a bullet is nothing compared to the power of an effective
combat robot weapon. You're not thinking about how the forces are
applied (and how big they are).
If I take a 25lb hunk of metal, spin it at 2000RPM with lots of
tool-steel teeth coming out of it and ram your aluminum armor at
15MPH, those panels would be ripped right off your bot and thrown
across the arena. I don't have to pierce the armor either. I only
have to hit the bot at a corner or where two pieces of armor come
together. Those teeth will dig in and peel it right off.
A bot named The Judge regularly pierced the steel BattleBot arena
floor (with an overhead spiked hammer) when attacking (and missing his
opponent). Just an example of the forces involved.
I can shoot a 2" plate of Lexan and have it completely stop a major
round. But, a combat robot can easily shatter and rip off that plate.
Different forces applied a different way to make Lexan useless above
the lightweight (60lb) class. Heck, it's not even enough anymore in
that class either.
Combat robots use some great alloys, 6-4 titanium, 2024 and 7075
aluminum, even Aeromet steel...and all of these alloys can fail.
Heck, even if the armor stays intact, all of the mounting bolts can be
sheared off....your armor flys away. And we're not talking about
serious bolts here...AN and NAS. Grade 8 bolts just shatter...too
And of course, your armor can stay completely intact but your
internals are scrambled from the forces being transmitted through the
armor and frame.
It really does require a whole new way of thinking about durability.
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