Near Space
Figure 14. Knot diagram.
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Next, add lines to the wooden
needle point loop so the
BalloonSat Carrier can be connected to the bottom of the near
spacecraft. How you choose to do
this depends on the design of
your near spacecraft. I design my
near spacecraft in nearly identical
modules.
At the top and bottom corners
of my modules are a loop of
Dacron and a one inch diameter
split ring. The tops and bottoms of
the modules link together with
Spectra Link Lines to form the
near spacecraft. Even my recovery parachute is attached in this
manner. Since I use square
modules, I have four linking points
on the bottom of each
module. So, my
BalloonSat Carrier uses
four lengths of Spectra
to attach to the bottom
of the near spacecraft.
Your design may differ,
so you may need a
different number of
Spectra lines in your
carrier.
If possible, use the
same holes for the
BalloonSat linking lines
to tie the near spacecraft
linking lines. Following
the same procedure
used for the first set of
lines, tie three-foot-long
Spectra lines into the
holes of the needle point
loop. Then, tie bearing
swivels into the ends of
the linking lines.
To attach my
BalloonSat carrier, I use
split rings to connect the
BalloonSat carrier to the
bottom of the near spacecraft. After attaching the
BalloonSat Carrier to the
near spacecraft, slide one
BalloonSat onto the lines.
Add a split ring to the
ends of each bearing swivel to keep the BalloonSat
from sliding off. See the
Figure 15. Carrier with Sat diagram.
94
diagram in Figure 15 if my directions
aren’t clear.
To add more BalloonSats, make
more linking lines by following the
same procedures as described
above. Cut three pieces of Spectra
three feet long, melt the ends slightly
to keep them from fraying, mark six
inches from both ends of each line,
and center a bearing swivel on the
marks and tie the swivels into place.
You’ll now have three additional link
lines with bearing swivels securely
tied to their ends.
To add the second BalloonSat,
link the new lines to the split ring at
the end of the BalloonSat Carrier
(after the first BalloonSat has been
added to the carrier). Slide the next
BalloonSat in place and add a
split ring to the end of the three bearing swivels to keep the BalloonSat
from sliding off. You can continue
this process for as many
BalloonSats as you need to fly.
However, keep in mind the weight
limits imposed by FAR 101 when
adding BalloonSats.
I see a couple of benefits in
using this design of a BalloonSat
Carrier. First, the multiple flight
strings will reduce BalloonSat swinging and spinning during the flight.
The BalloonSat Carrier forms a more
stable platform than a single flight
line because as the BalloonSats try
to swing or rotate, the other link lines
are put under different tension and
resist the motion.
As a result, images recorded
during a flight should show sharper
detail.
The second benefit comes
from using bearing swivels. The
length of the BalloonSat Carrier
can easily be changed from
mission to mission. If the next
flight carries more BalloonSats,
you just add an extension to the
current carrier.
Also, since the lines are linked
together, it’s easy to untie knots
that may form in the Spectra during storage. And by disconnecting
the link lines, tangling is reduced to
begin with. Bearing swivels let the
JULY 2005
