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PSA Microgravity Challenge
Preliminary Designs
New Market Middle School
Mrs. Laffer / Mr. Funk's 8th Grade, NMMS Team B:
Tyson, Gino, Ryan, Randy, Jon
We are in the NASA Quest PSA Challenge.
We are submitting our idea for a PSA maneuverer. We plan to use K'Nex
for our design. We will have a rail system built on top in a cross
shape, which, when made larger, will be a grid. Below the rails, is
a car powered by a k'nex motor--like a roller coaster. The car has
a winch below it that can pull the string up and down --powered also
by a motor. The string is connected to a tennis ball (PSA) so that
it can move up and down as well as in all directions.
We will probably test the maneuverer in the same environment as New
Market Middle School's other teams: between two powerful magnets whose
poles repel one another in order to suspend the PSA. We want to be
sure that using magnets won't "ruin" the PSA memory.
Response from Expert Dan Andrews:
I am interested in this one, because of the
statement, "weight = to PSA".
Is it your intention that when the PSA tries
to move up, the matching counterweight will move down?
I think you're onto something.
I have to admit, however, I do not understand
how the motorized winch comes into the equation. What does the winch do
that a simply pulley wouldn't do?
Answer from Gino
I'm responding to the question posted on Laffer/Funk's
8th grade PSA design. The idea of the winch instead of a simple pulley
system was so that the PSA could move up and down independently from its
front and back motions.
Also, though the counter-weight was included
in our design to simulate micro-gavity, the K-nex chain that we used as
our winch cable couldn't support the weight of an extra weight. It also
couldn't carry the 'PSA' front/back at the same time as up/down, once
again because of our weak chain (this would be made of metal on the ISS).
In our design, the up/down winch was carried on the
side-to-side one, which (once again) couldn't carry it. In microgravity,
none of the weight factors would hinder the mechanics of the winch system;
therefore, none of the problems we had here would actually
occur. Hope that clears things up!
Further "expert" Comment:
Thanks for the response... which of course
led me to more questions :)
You stated that, "The idea of the winch instead of a simple pulley
system was so that the PSA could move up and down independently from its
front and back motions". Are you saying that when the PSA moves left-to-right
(in your diagram), that the winch feeds more cable-out (or spools it up)
as you move so that the height of the PSA doesn't change? Does the counterweight
that offsets the weight of the PSA also offset the weight of the winch
and winch system? (You can see how complicated this can get when you try
this in three dimensions!)
You also state, "In microgravity, none
of the weight factors would hinder the mechanics of the winch system;
therefore, none of the problems we had here would actually occur".
While this is true, it really doesn't matter. The whole reason we are
creating this system is to enable testing the PSA, while here on Earth,
(gravity and all). On ISS, we have real microgravity, so no such winch-based
device would be needed... understand?
Answer from Gino
Thanks for your questions. Yes, the reason
for the winch is to spool up
and feed out cable as the PSA moves back and forth (and up and down
separately). And again, yes, the counterweight system we used to simulate
microgravity would offset the winch as well as the PSA.
As for your second paragraph, I guess I didn't
understand the reason for this experiment entirely. Either way, as I said
in my earlier response, the system that
would be the final testing 'mechanism' wouldn't be made of k-nex, as our
prototype is. Therefore, the stress applied by the weight of the winch,
PSA,
and counter weight could be held with much less difficulty than our plastic
chain and support towers.
-Thanks for the response
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