I. Introduction
My Level 3 Certification project is intended to bring back the fond memories of many High Power Rocketeers when, as youths, they bought their first Estes Fat Boy rocket kit, raced home to build it, and then out to the field at their local park or school to launched it for the first time. As that first launch screamed skyward a love affair with the Fat Boy rocket was born, to be nurtured thereafter. There is nothing new to modifying a Fat Boy, indeed I have seen it modified in many ways. I have seen multi-C and D clusters, single F and G engines, extension to its length, etc. My daughter received her first Fat Boy at 8 years of age and after 6 years she still flies it at almost every launch. It was her inspiration that convinced me to build a 6:1 scale up of the famous Estes Fat Boy as my Level 3 Certification Rocket.
It took some time to determine the exact level of scale up that would be easy to produce from available materials, look reasonable, and fly well on a "M" class motor. The decision to build a 6:1 scale up was primarily due to the availability of a 16-inch concrete forming tubes which gives an almost perfect 6:1 scaleup.
The finished rocket stands 79 inches high, 16.5 inches in diameter, with a span of 46.5 inches. The rocket weighs about 75 pounds before motor installation.
I to flew the upscale Fat Boy for a successful Level 3 certification flight at the G.H.S. launch at Rainbow Valley in Phoenix, Arizona on the weekend of October 11 - 12. I have flown it several times since and it is always a crowd pleaser.
At launch the rocket weighed approximately 94 lbs and flew to 3800 feet on a Ceaseroni Hypertech M 1010 4630cc standard grain hybrid motor. At apogee the Missile Works RRC2 altimeters fired off the pyrotechnic charges, separated the nose cap from the nose cone, and deployed the 9 foot homebuilt parachute from the top of the nose cone and the 4 foot sperachute for the nose cap. The rocket then descended to 800 feet AGL where the Missile Works altimeters fired off the second pyrotechnic charge, shearing the 6 - 4-40 nylon screws holding the nose cone to the main body tube and deployed the 15 foot military surplus chute. The nose cone descended on the 9 foot chute while the booster section descended on the 15 foot military chute. Both touchdowned softly, ready for another flight.
As always with any project of this size there has been many surprises and lessons learned that I hope to share with you in the description of this project. The greatest concern was stability because short fat rockets always push the classic 1 diameter rule between CP and CG. In fact, the original Fat Boy, built according to the instructions, loaded into Rocksim with a C6-3 has a stability index of .96 with Rocksim calculating stability and .67 using Barrowman equations.
I have been asked many times during this project 'how much did it cost', simply put, a lot. There were many unforeseen expenses along the way. I could not believe how much I spent in sandpaper and glue, not to mention altimeters, chutes, fasteners, and mistakes. I have tried to put the numbers together in a list for the benefit of those anticipating such a project, not as a deterrent, but as a reality check; because once you get started there is no looking back!
Last, I wanted to take the opportunity to thanks three individuals without whom I would have never accomplished this task - Brad Vatsaas, Paul Holmes, and Steve Lubliner. Their advice, suggestions, and personal time spent saved me countless hours and ensured success of this project. Additionally, members of the Southern Arizona Rocketry Association and Superstition Space Modeling Society have been instrumental in the success as well. A simple thank you is not enough. One of the greatest things about amatuer rocketry is the willingness of individuals to share their experience and ideas for the benefit of others. I only hope I will be able to return the favor to other inspiring rocketeers.
