Umbrella parachutes

The Thrifty Rocketeer blog continues...

About five years ago when I first got into Model Rocketry, my first few kits were a combination of Semroc and Estes Rockets.  Each one came with a plastic Mylar parachute, carefully folded and packaged in a separate plastic baggie or envelope. You had to carefully slice the package open to slide the parachute out. The trick was not to nick or cut the chute itself, which really wasn't a problem.

But after being folded and packaged for several months (if not years), the plastic parachute would have crease lines and a memory for being flattened.  It did not want to open or inflate on its own, let alone, during a speedy decent after apogee.

After almost crashing a few smaller rockets, or having the chute act more like a streamer than a parachute, an experienced rocketeer gave me some suggestions.  They included:

1. "Fluffing" the parachute before packing it back into the body tube.  
2. "Powdering" the parachute to remove any residual tackiness
3. "Crumpling" the parachute into a ball to resist the tendency to lay flat
4. "Knot" the parachute a third of the way down the shock cord so it won't slide.
5. "Swivel" joint the parachute to the shock cord so the chute can spin without tangling.
6. "Clip" the chute with a swivel onto the shock cord for quick interchangeable chutes

Now, there are probably a lot more tips and suggestions on how to rig a parachute than I have listed above. But these were the variety of tips that I got from the clutch of senior rocketeers that were gathered around my first near-crash.

Flash forward about six months to springtime as the launch season returned to Ohio. About a week before the next launch, I was driving my kid to High School after a dentist appointment, and passed something laying in the roadway. (Now, I know what you're thinking...and NO, it was not a rocket.)  The bright colored fabric was laying on the double yellow line of this two-lane road. I passed it, barely registering that it was some sort of umbrella that had been abandoned or hit.

But after completing my mission to drop the kid off at the high school just a 1/4 mile ahead, I returned via the same route.  And there it was, laying in the road, soaked by the spring rains.  I slowed my car and turned on the flashers, as I popped open my driver door,  I leaned out and snagged it.

It was a wine red nylon umbrella that had reversed or buckled and was ruined. It may also have been run over once or twice.  But that didn't matter to me, as I scooped it up and dropped it to the floor mat in front of the empty passenger seat in my car.  Another seven minutes and I was home, examining my recovered prize.

The wine red umbrella had a few holes poked through two of the panels where an umbrella spoke had doubled back and punched through.  But the metal ribs and handle were shot...bent, folded, crushed... no possible re-use.  But then a thought occurred to me.

I went to my wife's sewing table (please don't tell her) and retrieved a seam-ripper.  This tool is normally employed to slice a seam open by slicing the thread that holds it together.  I employed it to slice the threads that tied the fabric to each of the ribs and freed the fabric completely from the framework without any additional damage.

I turned the fabric over and laid it flat on the table. Each of the eight equal panels was a triangle, and it laid out almost flat. One of the panels had an extra ribbon with some Velcro on it to secure the closed-up umbrella, but that panel and the one next to it had a few minor scuffs and pinholes poked through from the bent ribs.

It occurred to me that with the seam ripper, I could open up the seams on either side of these damaged panels, and remove them.  By pinning the remaining six panels together, I could run one line of sewing down the seam and make a smaller, complete parachute.  It would still require some re-enforcement around the small spill hole at the top, and shroud lines.  But, it was essentially complete.

Almost immediately, my mind began to calculate how much I could sell something like this for. How much demand would there be for my new enterprise?  Could I set up a lemonade stand at launches and sell replacement chutes to desperate rocketeers? Would it pay for my sewing investment or maybe cover a few motors?

I sought out some shroud lines from a small ball of string that we had salvaged from some other project and saved in the junk drawer.  There were just enough feet of this more-than-string but less-than-cord line to complete three arcs of shroud lines. I was feeling very pleased with myself.

I asked my wife for some help with the sewing of the seam (yes, I let her in on the project) and then tacked on the shroud lines with some re-enforcing stitches on the sewing machine.

Then it dawned on me that my repaired chute was a good deal larger than the low power rocket chutes that I had been using.  In fact, it would have to be a larger body tube than I had ever used before.  I resolved to take the prototype to the launch with me and ask others.

The day of the launch, I described to one vendor and a senior rocketeer my idea, and got curiously little support.  They seemed to denigrate the idea of an umbrella chute, and did not encourage me.  At first, I thought it might be because  this represented a threat or competition to the vendor, who was in the business of supplying/supporting the launch.

But they said, "Go ahead and try it, if you want to risk a rocket...."  
 I didn't understand, and asked why they were doubtful. 

"Did you use rip-stop nylon," asked one?  I had never heard of it before.

"If I've invested more than a hundred dollars into my high-power rocket, I'm not going to skimp on an untested nylon chute," said another, "when there's a perfectly good one included in my kit.  Plus, he's got replacement chutes from a reputable manufacturer for sale right behind his table," he explained.

Crestfallen, I folded up my chute and packed it away.  I realized there was a lot more to this hobby than I had realized. 

But still, I saved my prototype, and over the last five years, I have salvaged golf umbrellas, school spirit umbrellas, clear plastic ducky umbrellas, Dora the Explorer umbrella and more.  By now, I must have almost a dozen various sized umbrella skins and my wife refuses to aid me in sewing any beyond that first prototype... so I learned to sew and repair them myself.

I just don't know if I dare risk a rocket on one yet.

How about you?  Have you ever experimented in making your own parachute for your rocket?  

Please tell me about it in the comments below. (And don't forget to tell me what size rocket you experimented with!)