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8.2.11 This thing looks weird sitting on the pad. How do I launch a glider?




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This article is from the Model Rockets FAQ, by Wolfram von Kiparski with numerous contributions by others.

8.2.11 This thing looks weird sitting on the pad. How do I launch a glider?

Since the motor is usually near the front of the glider, there
isn't much left of a 3' launch rod once you put a glider on
the pad. Frequently the glider will fall off the pop pod while
sitting on the pad. The other big problem is that once the
motor ignites, the clips fall, and can catch in the wings or
stab of the glider.

The solution to all of these problems is to launch gliders
from a "Power Tower". This is nothing more than a 3' dowel
with a launch rod on the top. Sharpen one end of the dowel,
and pound it into the ground. You can drill a hole for the
rod, or just tape it in place. I like to bevel the end of the
dowel at a 45 degree angle. A scrap ceramic tile with a hole
drilled near an edge makes a good blast deflector. Make sure
that the exhaust is directed AWAY from the glider, and not
back into the wing! The pop pod now sits on the deflector, and
the glider hangs below the rod, against the dowel.

To prevent the clips from catching the tail, you can either
tape the clip lead to the dowel, or better yet, use a second
launch rod about a foot away as a gantry, so the clips fall
away from the glider. A couple more rods are handy if it is a
bit windy to prevent the glider from blowing off the pop pod,
or twisting on the pad. Space them out near the wing tips.

I've gone one step farther, and made a 1/2 size version of a
Chad Pad. The base of the Chad Pad has extra holes in each
"leg" for extra launch rods to keep the wind from blowing the
glider around, and uses another rod as the gantry for the
ignition wires:

KGB Mini "Chad Pad" and tower parts list:

1 4' 1x2 (I used poplar instead of pine)
1 1/4"x2 carriage bolt
1 1/4" wing nut ("V" in drawing)
2 1/4" washers
1 1/4" lock washer
4 1.25" screws or nails
4 16p nails (double headed nails are most convenient)
1 ceramic tile, or stainless scrap
1 3/4" or 1" x 36" straight dowel
1 1/4" T-nut

Chad pad crummy ASCII art: (folded for storage)

						V
		+-------------------------------|-------------------------------+
		| |				|			      |	|
		+-+-----------------------------|-----------------------------+-+
		+-+-+ +-------------------------|-------------------------+ +-+-+
		| | | |				|			  | | |	|
		+---+ +-------------------------|-------------------------+ +---+

and opened

 
					      +---+
					      | x |
					      |   |
					      |   |
					      | o |
					      |   |
				      	|   |
					      | o |
					      |   |
					      |   |
		+---------------------------------------------------------------+
		| x	o	o	o      (o)	o	o	o     x |
		+---------------------------------------------------------------+
					      |   |
					      |   |
					      | o |
					      |   |
				      	|   |
					      | o |
					      |   |
					      |   |
					      | x |
					      +---+

The original chad pad was built from 8' of 2x4, I built a
smaller one of 4' of 1x2 for gliders. Take your 1x2 and cut it
almost in half, with one piece about 1/2" shorter than the
other. From the short piece cut a square off each end. Nail or
screw the two squares to the ends of the now significantly
longer piece. Drill a 1/4" hole through the center of the two
long pieces, and put a carriage bolt up through the bottom,
with a washer in the middle, and another washer, lock nut, and
wing nut on top. With the wing nut loose, the whole thing now
closes up as above, or opens into an "X". Drill holes in each
of the 4 ends for the 16p nails to add stability.

For the glider version, Bunny and I added a 3' dowel with a
threaded insert epoxied into the bottom. Cut the top at a 45
degree angle so the blast deflector sends the exhaust away
from the model (I use a scrap ceramic tile or piece of
stainless steel here) and add hole(s) for the desired rod
size(s). Remove the wing nut, and screw the dowel into the
carriage bolt, lifting the model up 3' off the ground. Perfect
for gliders. Add some holes along both base 1x2 for extra
launch rods to keep the glider wings from being blown around
in the wind, and to use as a gantry for the wires.

Finish the whole thing as you choose to protect the
wood. Bright colors or Aerotech style hazard colors might be a
good choice to prevent people from tripping on it. Rust-o-leum
BBQ black is a good choice to withstand repeated rocket
exhaust.

 

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