Squashed Balloon Parachute Deployment

| Squashed Balloon Parachute Deployment

"SQUASHED BALLOON
PARACHUTE DEPLOYMENT SYSTEM"
Another fun new addition to the water rocket world
developed by Gary Ensmenger

[note- 02/01/05 - PLEASE fill the ballon with AIR - not water]

The BALLOON has all the attributes we need for deploying parachutes. It's SAFE (except for choking), CHEAP (no bank loans needed) , LIGHTWEIGHT(to humans), SIMPLE (for some of us), RELIABLE, LEGAL (for Science Olympiad competition because it's non-metalic), COLORFUL, FUN, ADJUSTABLE (more on that later), BIO-DEGRADABLE (according to balloon package), and very AVAILABLE (you can buy them almost anywhere).

All of us water rocket enthusist have been scouring the earth for a good parachute deployment system for centuries. We've searched with NASA, electronic engineers, professors of universities, neuclear physcists, top rocket scientists, and we even called the physic hotline.

We forgot to consult with clowns! Not only do clowns use balloons to entertain children, but they have learned the intermost secrets of using balloons to fix cars, appliances, farm equipment, and highly guarded secretive stuff. So, now we too have tapped into the infinite power of the balloon.

Here's one of my favorite developements for water rockets. It's really too simple, yet the results are good. I look at it in amazement, and wonder why it took so long to come up with something so good. So remember, you hears it first here!

Above in the movie, you'll see a squashed balloon inside an OUTER SLEEVE (which is a cut NECK section of a 2 liter soda bottle). This assembly is actually under pressure, and mounted on a Bigfoot Launcher, on a tabletop. I used the "abort valve",(one of the features of the Bigfoot Launcher), to bled off pressure. When the pressure decreased to 24 PSI, the balloon can finally move the OUTER SLEEVE up and away. In flight, the outer sleeve is KICKED out of the way by the balloon, and a parachute is deployed.

WHAT LEAD TO THE DISCOVERY?:

I have found that in surveying circumferences of many 2 liter soda bottles, there appears to be THREE predominant SIZES, (and sometimes sizes in between). The prevailing circumference sizes are 13.5, 13.563, and 13.625 inches. Since the thickness of one wall is only .0123 inches, there is room for all three of these sizes to freely "telescope" inside each other. I was using these "telescoping size" differences to make perfect "butted curled edges & circumference splice" joints for multiple bottle rocket bodies. (I will be adding another page about that later.)

Since a 2 liter bottle expands about .188 inch in circumference when pressurized, there is enough expansion to interfer with the telescoping of an outer sleeve, even when using the extreme differential sizes of an 13.625" sleeve over a 13.5" bottle. The ideal of course is to use sizes that allow EASY telescoping, yet as tight as possible. The 13.563 inch circumference is more plentiful on the average, so I like to make that the body of the rocket, and the 13.625 inch circumference is chosen for the outer telescoping sleeve.

WHY IT WORKS:

The problem with previous attemps to separate a nose cone from the main body of a rocket is that usually the nose usually travels with the body of the rocket. The SQUASHED BALLOON wants to return to it's original shape of roundness, but can't when the walls of the rocket are swollen with pressure. When the rocket body looses enough pressure, the balloon can return to it's original shape, and "KICKS" the nose cone away from the rocket.

"Water Bomb" balloons seem to be ideal size for this application. Blow them up to about 3.5 inch in diameter. The length of the outer sleeve will be cut to allow overlap with the squashed balloon, and no overlap when the balloon returns to it's original shape. The size of the balloon regulates how long the outer sleeve will be.

If you need "nose weight" for extra height, adding weight in your balloon is a perfect place. I find about 4 ounces of water works great.

With a restricted orfice "robinson coupling" (threaded lamp rod), the deployment of the parachute can be delayed. I also make an adjustable orfice that can be adjusted with a copper penny on a stick, so the adjustment can be fine tuned for those that want apogee parachute deployment.

The parachute is rolled and positioned below the balloon, as seen in this last picture. I tied the ends of the parachute strings to the neck of the rocket.

VERY IMPORTANT -- the top outer sleeve MUST BE VENTED, below the balloon level. I melted holes with a hot nail and then used a wood chisel to plane off any raised edges on the INSIDE. If you melt, drill, or cut, just be sure you (1) don't raise the surface on the inside, (2) provide enough ventalation so the nose will KICK off freely. Otherwise, there will be a SUCTION, that will impede deployment.

FINE TUNING TIMING -- Another way to delay the timing of deployment is to restrict ventalation. With experimentation, you may find the desired amount of ventalation area. If you drilled too many holes, you can slowly scotch tape over some of the holes to see if you get closer to apogee deployment.

HINT: One way to stage this system is to tape the outer sleeve in position (with the balloon squashed). Fold one end of the tape over oneto itselt to create tabs for you to grab. Tape twice on opposite sides. After you reach 40 psi, you can safely remove these two tabs. Resume pressurizing to your desired level.

This outer sleeve actualy helps reinforce the rocket body by giving it another layer of PETE. This acts as an "explosion jacket" and give more protection.

Another idea to increase flight time is to jettison the nose weight from the rocket at deployment time. If you used a water ballon, you could put a parachute on the water balloon and another parachute on the rocket.

THE FINNED SLEEVE:

Another thing I have been doing lately is to make another outer sleeve for the bottom of the rocket and putting the fins on the outer sleeve.
I also do a "CURLED EDGE" on the very bottom of this outer sleeve for ridigity. I tape this "finned sleeve" around the circumference to prevent it from sliding off. I also pick a tighter fitting outer sleeve. My feeling is that by "sleeving" the bottom section too (with a tighter fitting sleeve), it will force more pressure to the upper section of the rocket body for improved deployment action. ALSO, I'm getting double duty "explosion jacket" because now both top and bottom of the rocket body is "jacketed". This is much easier that using filiment tape.

Another reason for liking this "finned sleeve" is that I can now extend the position of the fins LOWER than I could when attaching fins directly to the body of the rocket. Also, I can SWITCH this "finned sleeve" to other rockets, thus reducing my required fin inventory.

PICKING THE RIGHT SIZE SLEEVE:

Now that we know that you can select different size 2 liter bottles for specific purposes, you can pick an outer sleeve that won't bucket the walls of the rocket body. I'm betting the with the right selection, you will be able to find five telescoping sleeves that won't buckle each other.

In determining the circumferences of the bottles, first remove the labels and debris. I use a nylon strap that is marked with ball point pen lines. Then I use a felt tip marker to write the size (my own code) of each bottle on the side of the bottle. Then I sort the bottles according to their sizes.

STRONGER GLUE JOINTS:

Now, when I assemble rockets and their extra (internal & external) parts, I don't have to force (and buckling) anything. Everything fits and slides perfectly. I also think that this has INCREASE THE BONDING STRENGTH of the PL Premium Construction Adhesive. The reason is that now the PL Premim has a wall thickness of .015 to .020 inches between the PETE plastic walls. Before, when I was forcing splices, the PL Premium was mostly squeezed out to only several thousands of an inch.

Well rocketeers (& clowns), have fun. This is your CHRISTMAS PRESENT for 1997. Hope you like it. Merry Christmas.......Gary.

RETURN HOME