Long before I was building rockets, a very small, tumble recovery rocket was introduced by Estes. It was the 1/2A powered Astron Sprite. To those not familiar with this rocket, I would like to explain a very unique characteristic of this design. When scaled up enough to be powered by a high impulse motor, the air flowing past the fin ring creates a high-pitched whistle when launched. This is sometimes drowned out by the initial noise of the motor, but is quite audible as the motor burns out and continues during the coast phase.

Back in 1999, during the second launch of my 4-inch airframe based Superscale Sprite, the whistle was clearly heard by all those in attendance. As the rocket arced over, even before the ooh’s and aah’s had subsided, it was obvious that I had a major deployment problem…there was none! The Sprite raced back to earth, and a fact that I was previously unaware of, became perfectly clear. This amazing rocket whistled coming down, louder than when it was going up. In fact, it whistled right up until it impacted with the rock-hard Pennsylvania soil at our Jones Farm launch site. Naturally, my fellow rocketeers were quick to offer their condolences, but I was more amused by the memory of it whistling back to Earth. I collected the remains, including digging the nosecone out of the ground, and went back to my truck to prep my next rocket.

My son, Chris, almost immediately began urging me to build another one. Due to the amount of work that was involved in the project, I was unwilling to commit to such an ambitious undertaking. Over the next twelve months or so, I did acquire a piece of 15-inch diameter cardboard drum, which would make a fine fin ring, (my first one was 11.5-inch diameter) and a 24-inch long section of 5.5-inch airframe. This would amount to a 7.3X version of the original Estes model. I also purchased a 3 x 6 x 36-inch block of balsa wood, that I planned on using to turn a scale nosecone. I cut the block in two and laminated them together to make a nice 6 x 6 x 18-inch blank, and then set it aside, where it would sit for almost another year. One weekend in February of 2001, I was turning a couple wooden nosecone patterns for a Tripoli Pittsburgh group project, the Gloria Mundi III. After completing this task, I decided to go ahead, and turn the new Sprite nosecone from the balsa block that had been collecting dust. After finishing the outside form, it was necessary to hollow out a large section of the cone so that I would be able to add the one-pound of weight needed for stability. I cut a bulkhead from .5-inch plywood to seal the opening that was epoxied into place after filling the cone with expanding foam. Before I knew it, the nosecone was complete, and I was planning my next steps of the project, that would soon come to be known as "The Lord of the Rings."

Next, I carefully cut a 5.5-inch section of the cardboard drum, and prepared it to be reinforced with a few layers of fiberglass cloth. I opted for two wraps of 6-ounce woven cloth and a finishing wrap of 1.5-ounce cloth. The last layer was done solely to make it easier to get a smooth surface for painting. I used the same process for the airframe, which, although it was made of flexible phenolic, was not strong enough for a project of this size. I printed patterns for the fins and fin-caps using RockSim 5.0 and cut them from .25-inch aircraft plywood. Two centering rings were cut from the same material, also using patterns created from RockSim. Twelve inches of 38mm motor mount tubing was cut and I had all the parts necessary to complete the project.

A large T-nut was installed in the forward centering ring for recovery system attachment, as well as two in the rear ring for motor retention. The forward ring was epoxied to the motor tube, and this assembly was installed into the slotted body tube. With the rear-centering ring temporarily put in place for alignment purposes, the fins were epoxied into place. The rear ring was then removed, and internal fillets used at both the motor tube and the inside of the body tube. Since I was going to be using rail guides instead of launch lugs, the guides were secured with nuts from the inside of the airframe at this time. Before permanently installing the rear-centering ring, the remainder of the cavity was filled using 2-part expanding foam. Fillets were added to the fins at the outside of the airframe for added strength, using a combination of epoxy and micro-balloons.

It was now time to attach the fin ring and fin caps. Careful attention was paid to the alignment of the caps so that minimal filling of gaps was necessary. When the assembly was completely dried, I once again used the epoxy/micro-balloon mixture to create fillets both inside and outside the fin ring at each fin and fin cap. I used grain filler on the plywood fins, and after some extensive sanding, was finally ready to prime the entire rocket. More sanding, filling and priming followed, of course, until I was ready to paint. After adding an 18-foot, 5/8-inch tubular nylon shock cord and a Sky-Angle 52-inch parachute with Nomex protector, the total weight without motor is just over 8-pounds.

I launched the completed project at our first Dragon's Fire launch of the season, April 7th, 2001. According to simulations done in both RockSim and wRASP, it reached a max altitude of approximately 1900 feet on an Aerotech I284 reload. Unlike my first Sprite, the whistling only occurred on the way up.