DBF Q&A #1
This is the first of the 2001 DBF Question and Answer e-mails. They will be
sent periodically to the e-mail address of all participating teams. They
will also be archived on the DBF contest site. Please continue to send your
questions to: [log in to unmask], and besure to include "DBF"
in the subject line.
I sent an e-mail test out to all the teams last week, and have not received a
reply from all the schools yet. Please make sure you check your contest
e-mail frequently. It is especially important when we get close to the
contest dates, as there may be last minute information and this is THE ONLY
WAY that teams will be notified in nearreal time.
If you haven't sent in your e-mail test reply yet, please do as I still want
to verify all e-mail addresses. Missing as of this morning are: West
Virginia #1 and #2, Tennessee Tech, Queens University, UCLA, Wichita State,
Syracuse, Univ. of Texas at Arlington, State University ofNew York at
Buffalo, and City College of NY #1, #2 and #3.
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There have been several questions asked regarding the use of a"speed
loader" for the cargo change out. For the benefit of new teams who have
not seen the speed loaders used in prior contests I'd like to add a little
more explanation than is in the rules. For the benefit of old teams, note
that their are new requirements on the loaders this year compared to designs
allowed in past years.
Question: Can we store the tennis balls in a tube so as to allowfor easy
unloading/loading?
Question: How much of the plane is allowed to be changed with each sortie.
For example is the tail allowed to be part of the speedloader and be switched
with an identical tail each time?
Question: Is it admissible to have two identical speed loaders, one loaded
with tennis balls and one loaded with the steel blocks?
Question: Are we allowed to prepare twoboxes with same dimensions, one for
tennis balls, and the other for heavy payload so that we can replace the box
with tennis balls with the box with heavy payload between the sorties?
Question: Can the speed loader be exposed, as part of thefuselage or must it
be entirely enclosed?
Answer: The idea of the speed loader first came about several contests ago,
where it was considered a competition sensitive idea. Since teams from past
years have had the opportunity to see the speed loader idea, it seems only
fair to new teams to make it a common feature, rather than act as an
advantage only to teams who participated in past years. That is why it was
specifically added to the rules for this contest.
<blockquote type=cite cite>For both the heavy and light payload teams
mayemploy a removable container or "speed loader". The container
must be the same size and design for both payloads, but may employ different
means to secure the payload internal to the container. Containers must be
"reusable", meaning that they can be opened/closed multiple times
(can not be glued shut) and employ reusable mechanical fasteners to secure
the payload inside. Teams may be asked to demonstrate removal of the payload
from the container by thejudges</blockquote>
The idea of a speed loader is to allow some form of container that contains
the payload which can be more quickly installed in the airplane than can the
individual payload pieces, for this year either multiple steel blocks or
multiple tennis balls. In it's simplest form itwould be either a simple box
or tube.
You may have several loaders, each with a different payload, ready foruse on
individual laps (sorties) of a given flight period. For example you can have
a loader setup with 10 lbs of steel and another set with 6 lbs, and may
select which one to use on any given "heavy" payload flight. You
could also have one loader pre-loaded with 10 tennis balls, and another
pre-loaded with 50 balls. You can take all of the loaders you may want out
to the flight line with you and select them based on prevailing
weather/wind,state of your batteries, etc.
The speed loader may not be a prime structural part of the airplane (as the
airplane must be capable of flying without any payload), so it couldn't be a
replacement wing, fuselage, tail boom etc. It can be a part of the airframe,
such as a hatch or store pod.
The speed loader for each payload is specified to be the same size (and
construction) for each payload for this year. That means that if you wanted
to use wing store pods, they would have to be the same size for each payload,
so you can't have a small streamlined pod for the steel blocks and a large
bulbous pod for the tennis balls. You also can't fly just one pod for the
heavy payload, and several pods for the tennis balls. Similarly you can't
have a flush hatch for the steel payloadand a bulged hatch for the tennis
balls.
Also, since the rules state the payload must be internal, you can't have a
steel block "bolted" to the outside of the fuselage (the same goes
for the tennis balls, though it might have been interesting to see how
someone might secure a dozen or so tennis balls to the outside of an airplane
and still make it fly :-) ). A wing mounted pod, since it must be present
for all flights under the rules, is consideredpart of the structure and can
be used to house the payload, not just thefuselage.
Please also note that this years rules require the speed loaders
be"reusable", so you can't glue the tennis balls into it, but would
have to use a removable lid on the loader to restrain the balls or an
internal baffle or net to contain smaller numbers of tennis balls. You could
however have the lid restrain the tennis balls, and have a steel stud in the
bottom that contained the steel blocks, and the stud would only need be
present in the loader containing thesteel.
And finally, although not specifically stated in the rules (though it is
alluded to), the payload MUST be restrained in the loader. The tennis balls
(or the steel) can't be just allowed to roll or slide around inside the
loader. For flight safety, the judges reserve the right to tip the loader
upside down, on it's end or side, etc to make sure thepayload cg can't shift
during the flight.
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There have also been several questions (mostly during the summer) regarding
the engine REP formula for multiple motors. I've only included one typical
question below.
Question: Could you please clarify the formula for Rated Engine Power given
in the rules for the 2001 contest? If a team uses two motors at 500 Watts,
does that "cost" the same as using a single motor at 1000 Watts?
Also, if a team uses multiple motors, will they also be allowed to use
multiple fuses to protect each motor individually?
Answer: The is a fairly detailed answer to this in the FAQ. I encourage all
teams to read the entire FAQ carefully, as it contains information for this
contest year, and also items that were raised in past years that new teams
might not be aware of. From the FAQ....
<blockquote type=cite cite>Question: How is the maximum currentlimit (40A)
applied to multiple motors and battery packs? Is theresupposed to be one
40amp fuse for each motor or one fuse for allmotors?
Answer: The 40A limit can be considered as a system wide current limit. No
motor or battery may see more than a 40A current. Therefore, if you have two
separate packs feeding two separate motors, each motor/pack would have a 40A
(max) fuse. If there is one pack feeding two motors, there would be one 40A
(max) fuse at the pack. Finally if there is onepack feeding one motor, there
would be a single 40A (max) fuse at thepack. </blockquote>
<blockquote type=cite cite>Question: In the cost formula the REPequation
contains both the number of engines, and the number of cells.How are multiple
engine REP's computed?
Answer: The REP is computed for each engine multiplied by thenumber of cells
powering that engine. The individual engine REP's arethen summed for the
total REP.
For example:
(1) If there are 2 engines connected to a single 20 cell pack, the REPwould be
2 engine*40A*1.2V*20 cells = 1920
(2) If there are two engines each connected to a separate 20 cell pack,the
REP would be
1 engine*40A*1.2V*20 cells + 1 engine*40A*1.2V*20 cells = 1920
(3) If there are tow engine each connected to a separate 10 cell pack
(20cells total) the REP would be
1 engine*40A*1.2V*10 cells + 1 engine*40A*1.2V*10 cells = 960</blockquote>
-Greg
<div>Gregory S. Page</div><div>ITT SES</div><div>2560 Huntington
Ave</div><div>Alexandria VA
22303</div><div>202-404-1251</div><div>202-767-6194 FAX</div>
<div>email: [log in to unmask]</div><div>email:
[log in to unmask]</div><div>Contest web page:<A
HREF="http://amber.aae.uiuc.edu/~aiaadbf">http://amber.aae.uiuc.edu/~aiaadbf
</A></div>
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