Notes on an Aerolight Shell for Small Rockets

WARNING AND DISCLAIMER:  If you are underage, then consult with your parents or guardians before attempting any of this.  You are on your own - I'm not responsible for your actions or harm you may bring to others because of your actions.  Making the items described below  can result in injury or death to you or people in your vicinity. Some things mentioned here may be illegal to make in your city, county, state, or country so check the laws that apply to you before you attempt anything described here. These notes are not complete on purpose. If you are reading them and new to pyrotechnics, then you are making a mistake. Stop now - this page is not for you. Get a beginning book on fireworks (see Skylighter or American Fireworks News (very quick shipping)  for a start) and read up. You can't make any of this work without more information so read up or join a club or ask someone to help you.

 

Click on the above to see a terrible movie of the
aerolights made below in action (I'll have to get a better example
but for now...)

This is a note on a single break canister shell that can be scaled up or down to fly on various size motors. The payload will be six aerolights - which are kind of a cross among a comet, crossette and tourbillion. They are described by Lancaster as comet bombs and by Weingart as aerolights. In addition, in BAFN IV, page 54, there is another discussion of them.  The one described here will be a modification of all those.  Other than the aerolights, much of this construction is like the Cap Plug Shell . Refer to that page to see how to make the basic canister to hold the aerolights.

The following pictures and captions show one way.  You may wish to do it more traditionally.  This is a rocket header so it does not need to be pasted in. Pasting primarily provides fireproofing but we can make the header fireproof enough for a rocket launch without all that extra weight.  

Motor Configuration - 3/4"

The total weight of this shell varies depending on what size inserts you use. If you use 5/8" inserts (shown) it will be about 245 grams - which can be lifted with many 3/4" BP motors although this is a bit heavy compared to our other 3/4" examples. If you use the 1/2" inserts, the shell will weigh about 130 grams and can easily be lifted by most 3/4" BP motors.  The BP motor can be nozzled or nozzleless so see the rocket section on how to build one. The one used for this shell was 3/4", 4" spindle with a 3/8" base and a 1% taper. It used a clay nozzle and a clay bulkhead. The fuel was RP equivalent (see composition page). The delay was 3/4" of the same fuel with 20% Ti added. The dimensions of the spindle are similar to the LWS motors produced by Steve La Duke and his tooling set would work fine.  If a 'standard' BP spindle is used, then the fuel will need to be slowed down by adding charcoal - start with about 5%.  I use two sticks on each motor - one is 5/16 x 32 and the other is 1/4 x 18.  For slightly heavier shells (200 grams or so), I increase the 18" stick slightly.  For lighter shells, I decrease it or remove it. For instance, for the five times report shell which is less than 100 grams, I remove the 18" stick entirely.

Make a lightweight shell case first. 


To see how to make these, go to the five times report shell - This case is
2.5 inches in diameter and is for the 5/8" inserts. The case for the 1/2" inserts
is 2 inches in diameter



Make the insert tubes or buy them

You could use just about any type of tube for these inserts.  Generally, you want the star to be easily seen so I recommend you go with something 1/2" or bigger. Start with 1/2" with a 3/4" motor.  I didn't have quite the size tubes I wanted so I decided to roll my own from manila folder paper.   Click here for a step-by-step of rolling an insert tube. The insert tubes I settled on were 5/8" x 2.5" for the large version and 1/2" x 2" for the small version.

 

Make the inserts for the shell

The big inserts are 5/8" x 2.5" aerolights that could also be used in an aerial shell. However, these aerolights are not the ones grandma used to make. One end is a magnalium star and the other is a time fused salute. The intent of the separately fused salute is to get all the salutes to pop as close to the same time as possible. About 3/4" of space in the insert is reserved for the star and the rest for salute filling.  The time fuse is 1.25" between punch holes.  That should give about 4 seconds delay. The shell has to survive the burst so use epoxy on the time fuse where it enters the case. The case size for the 5/8" inserts is 2.5".

The small inserts are 1/2" x 2" and can be used on most 3/4" rocket motors. These inserts, because they are smaller, are built more traditionally - with no time fuse. The case size for the 1/2" inserts is 2".

For these shells, the following are the star mixes.  These are heavily modified rocket fuel mixes that burn a little more slowly but are quite bright.  You could also use any of the parlon stars in the compositions page.  See Gary Smith stars for example. Be sure to use lacquer thinner or acetone to wet these.  The parlon not only binds the composition it seems to make them light and burn a little more vigorously. If you use water and stuff them into the tubes, it probably won't work at all.

Red Star Mix

Strontium Nitrate                            55
Magnalium, -325 mesh powder        14   
Magnalium, -100 mesh powder        14                                       
Parlon                                            17
Coarse Ti  (10-30 mesh)                  20

Total                                            120

Green Star Mix

Barium Nitrate                                60
Magnalium, -325 mesh powder        12.5%   
Magnalium, -100 mesh powder        12.5                                        
Parlon                                            15
Coarse Ti  (10-30 mesh)                  20

Total                                             120


Put a piece of tape on a mandrel that stops the
mandrel 3/4" from the end of the tube

Looks like this

Put in some glue

Add a bulkhead made from chipboard (or purchased).
You may have to cut a hole in it if there isn't one.

Glue the top of the bulkhead, too. The hole is a 'belt
and suspenders' addition. If the cross match fails to
light the fuse, the star will burn through here and
ignite the salute.


If you are making 1/2" aerolights then you won't put
time fuse in the rear. While you could let the star mix
ignite the salute, it is kind of nifty to use a piece of
Visco as a burn rate controller - that way the salute
will pop at about the same time as the others.


For each color of star mix, make three pots.  One pot
that is 100% star mix. One pot that is 50/50 star mix
and prime (BP +10% parlon), and one pot that is pure
prime.  Wet all three to clay-like consistency. Use
lacquer thinner or acetone - not water.

Scoop in some star mix. Stop about 1/4" from top.
put a dollop of 50/50 mix in. Put a dollop of prime
in.


Press the mix with another mandrel between dollops.


If doing the Visco option, then use a mandrel with
a hole in it so you can surround the Visco and get
the star mix well packed.

When done, dip the end in some BP and you have a
primed star that will light quite easily. Mark the tube
with the color you put in it!

If making the Visco version, trim the fuse down
to the prime now

At this point, I like to secure the tubes so they don't  get
all messed up.  Film cans work - or holes drilled in a 2x4
work, too.  Make up your burst mix. You can use flash,
BP, whistle or about any combination. 5/8 cases use
about 8.5 grams of mix each. 1/2 cases use about 3 grams
 

After filling the tubes, they should be within a 1/4"
of the top. You can cap these off with epoxied end
plugs if you are making the smaller version of the
aerolights (1/2" x 2") or you don't wish to synchronize
the timing of the salutes.

If you are making the larger version of the aerolight inserts
(the 5/8" version) and wish to synchronize the timing, make
up some time fuses and some end plugs. These fuses are
cross matched at 1.25"

When all the fuses are inserted, you should have at
least 1/4" of space between the end plug and the top
of the insert.  This will be filled with epoxy. Don't shirk
on the spacing - you want it tough because it has to
survive a burst.  If one insert ruptures, they will all
detonate.

Fuses all epoxied up. Just add black match to the
fuses and the star end and we are ready to go.

Here is a finished 5/8" aerolight. Note the length of
black match that is tied onto the primed end. A dot of
super glue is put on the tie and the edges of the black
match to insure it doesn't blow free on the break. The
fuse is crossmatched as normal.
 

 

Fill the shell casing

A 2 1/2" shell case is used for the 5/8" insert version with no chipboard inner sleeve. However, you have latitude on the size and number of inserts.  I know one pyro who puts 10 1/2" tubes in a case just a bit larger than this one.


Put 1/4" of burst (bp on hulls in this case) in bottom

Arrange aerolites around in a circle - put a dummy
case in the center to temporarily hold the aerolights in
place.

Here is the 1/2" version. Six fit nicely in a 2" can.
 

Tamp in burst to the 1/2 way point

Add three grams of burst enhancer - slow flash in this
case but whistle would also work. Also add the
passfire tube as in the color in a can example.

Just for insurance, prime the top of the aerolights



Fill to about 1/4" over the inserts and seal off with
an end cap

Fold over paper and glue

Spike the shell

See the spiking example at the color in a can page.

Priming Alternative

You can also drill back the inside of the aerolight so each one has exactly the same amount of composition and then prime the end with a hot metal based prime. This one is BP with 10% silicon added - Ti or other metal will work, too. The BP mix was made into a thick slurry with NC lacquer and dabbed on. It was tied down with black match so the prime wouldn't flake off at the burst. Test this configuration to be sure it will light your composition but it should work fine.