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Les Kramer's L-3 Certification Project
 
INTRODUCTION
This website will document my Level 3 certification attempt. The intent for my L-3 project is to build a rocket capable of NOT just using an M class motor. I would like to be able to fly it on smaller 75mm and 54 mm motors. The certification flight will take place in 2006 at Geneseo, NY. This particular field has a standing FAA waiver of only 8,000 feet and therefore my rocket will have to maintain a safe margin below that altitude. This altitude limitation presents some challenges. The rocket has to be heavy enough to stay under the waiver yet not too heavy as to prevent me from flying it on smaller motors.
My rocket choice is a 1/3 scale of an ARMY Honest John surface to surface missile. This rocket is based on SMOKIN' ROCKETS Honest John. The major components of the rocket include a custom made PML fiberglass nose cone, flexible phenolic 7.5” tubing, a 75mm phenolic motor tube and 3/8” thick, 7 ply, plywood fins with routed leading and trailing edges. The fins and nose cone were purchased from SMOKIN' ROCKETS. All other components will be purchased from Giant Leap Rocketry. The rocket achieves dual deployment with the standard method of “breaking” the booster at the altimeter bay at apogee and “pushing” the nose cone out of the parachute section at a predetermined altitude. The main tubes will not use fiberglass except for 4” strips where zippering could occur. The main tubes will gain their strength with internal components. West System epoxy (105 Resin and 205 or 206 Hardener) will be used throughout the construction process. Where required, the epoxy will be thickened using #404 and #407 fillers.
The primary means of propulsion will come from an Aerotech M1315 motor. A safe velocity of 44 feet per second will be achieved prior to the rocket leaving the 10’ rail to ensure stability. The rocket will maintain a safe 4:1 average thrust to weight ratio.
The altimeter bay will be constructed of a flexible phenolic coupler section with internal supports for strength and bulkhead end caps. The altimeters (1-Missile Works RRC2 and 1- PerfectFlite MAWD) will use separate power sources, separate electric matches, and separate black powder charges. The altimeters will be wired with on / off switches and each will have a separate switch to arm / disarm the ejection charges. Both of the altimeters will be flight tested.
The recovery system is a drogue less design and will use a SkyAngle Level 3 Cert parachute. The rocket sections will be connected together using 1” tubular nylon with sewn loops from Rocket Rage. Each shock cord will be connected to rocket sections using stainless steel quick links and U-bolts. The parachute section will be secured to the altimeter bay with stainless steel screws. The booster section will be secured to the bottom of the altimeter bay with (3) #2 nylon screws acting as shear pins. The nose cone will be secured to parachute section with the same shear pin method.
The major areas of safety concerns are as follows:
1.) Failure of the apogee ejection charge causes a ballistic re-entry
2.) Failure of the main parachute ejection charge causes a ballistic re-entry
3.) Drogue less design allows the separated rocket to fall in a ballistic fashion.
A primary focus of the entire construction process will be the overall weight of the rocket. Simulations will be performed under different environmental conditions to ensure a favorable 4:1 thrust to weight ratio. Particular emphasis will be placed on the initial thrust to weight ratio and the speed of the rocket off of the rail. The design of the rocket is slightly over-stable and therefore careful consideration of launch day wind speeds will be very important. The rocket will not be launched with wind speeds over 10-15 MPH.
Complete redundancy and prior flight testing of the ejection system will reduce the risk of the ejection charges not firing at apogee or main deployment altitude.
The major areas of certification failure are as follows:
1.) Broken fins upon impact
2.) Zipper of a body tube
Lamination of the fins with fiberglass will help mitigate the chance of a broken fin.
The ends of the body tubes of the booster section and the parachute section will use a 3” wide layer of 5 oz. Kevlar Tape covered with a layer of 4" wide layer of 8.7 oz. fiberglass tape for additional support and protection against zippering. Also, custom made tubular nylon "V" harnesses will be used in the booster and parachute sections. These will extend 3 feet beyond the ends of the tubes then connect to the standard recovery harnesses.
There are five additional sections detailing my L-3 journey. They are as follows:
CAD/SIM FILES
CONSTRUCTION
RECOVERY SYSTEMS
CHECK LISTS
CHRONOLOGY OF EVENTS
ACKNOWLEDGEMENTS
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