1	Hey Bubba, Watch This! Level 3 Certification Package Chuck Pierce TRA 9308 NAR 78629 Southern Thunder Launch Manchester, TN June 3, 2006 TAPs: Walt Stafford, Tom Binford
2	Overview The objective of this package is to discuss the design, configuration, and test history of Hey Bubba. Rocket Overview Aft Airframe (including motor mount) Construction Forward Airframe Construction Nose Cone Construction Avionics Bay Construction and Function Recovery System Construction and Function Rocket Attributes Flight Predictions
3	Rocket Overview Construction Hey Bubba has been constructed from Performance Rocketry components Two 6” dia x 48” long Fiberglass airframe tubes Fiberglass Fincan 5:1 Ogive Fiberglass nose cone Bulkheads and Centering Rings are handmade from ¾” Plywood Final Specifications Mass (no motor): 28 lbs Mass (with M1350): 40 lbs Final Mass: 33 lbs Stability Hey Bubba has been verified to have 2.5 to 3.0 calibers of stability, based on Barrowman and RockSim CP calculations, respectively
4	Aft Airframe Construction Airframe: Performance Rocketry 6” OD, 1/8” Wall, 48” long Fiberglass Tubing Motor Mount Assembly Motor Tube 3” ID x 1.8” wall x 31” long paper tube 4 Plywood Centering Rings, ¾” thick Epoxied to motor tube and airframe ID Forward-most and two aft-most CRs are also attached to airframe with three #8-32 CRES machine screws Aft-most CR is chamfered ½” is same OD as airframe and is external to Airframe ¼” is same ID as airframe and is internal to the Airframe Purpose of chamfer: To allow the aft CR to apply the thrust force directly into the long axis of the airframe, thus helping to avoid a shear failure of the MMT inside the airframe.
5	Aft Airframe Construction (Cont) Forward Bulkhead ¾” Plywood Attachment to Airframe Epoxied to ID Three #8-32 machine screws through Airframe into bulkhead Motor Retention 3/8” hole in bulkhead 3/8” x 6” threaded rod screws into Motor bulkhead. Washer and wingnut attaches motor and retention rod to bulkhead Drogue Parachute Harness Attachment 5/16” U-Bolt permanently attached to bulkhead Offset off airframe centerline to allow access to retention rod Volume of Drogue Chute Compartment is 424 in³
6	Aft Airframe Construction (Cont) Fin Set Single-piece Performance Rocketry Fiberglass 3-fin Fin Can Flush with aft side of Aft CR (½” aft of airframe tubing) Epoxied to OD of Airframe Mechanically attached with six #8-32 CRES screws 3 each into two aft-most Centering Rings Rail Guides Rail Guides are screwed into aft-most and forward-most Centering Rings with #8-32 screws Nylon insert allows Large Rail Buttons to be securely attached May also use Small Rail Buttons, if desired, for future flights.
7	Aft Airframe Construction (Cont)
8	FWD Airframe Construction Airframe: Performance Rocketry 6” OD, 1/8” Wall, 48” long Fiberglass Tubing Coupler Performance Rocketry Fiberglass Coupler, 12” Long 6” permanently attached in Airframe Epoxied into ID of Airframe Six #8-32 screws run through Aiframe and Coupler and into bulkhead (3 screws attach to two bulkheads ¾” Plywood Bulkhead terminates aft end of Coupler 5/16” U-bolt permanently attached to bulkhead Drogue Ejection Charge Terminal Blocks permanently attached to bulkhead Bulkhead epoxied into ID of Coupler. Three #8-32 set screws further secures bulkhead Avionics Bay enclosed in forward end of Coupler Forward Bulkhead (¾” Plywood) Attachment to Airframe Epoxied to ID Three #8-32 machine screws through Airframe into bulkhead Main Parachute Harness Attachment 5/16” U-Bolt permanently attached to bulkhead Offset off airframe centerline to allow access to retention rod Main Ejection Charge Terminal Blocks permanently attached to bulkhead Volume of Main Chute Compartment is 707 in³
9	FWD Airframe Construction (Cont)
10	Nose Cone Construction Performance Rocketry Fiberglass Nose 5:1 (eg, 30”) ogive 6” long shoulder ¾” Plywood Bulkhead terminates aft end of Coupler 5/16” U-bolt permanently attached to bulkhead Bulkhead epoxied into ID of Shoulder. Three #8-32 set screws further secures bulkhead
11	Avionics Bay Construction & Function Construction Internal ¾” Plywood Bulkhead located flush with aft end of airframe. Closes aft end of Avionics Bay Internal ¼” plywood bulkhead closes forward end of Avionics Bay Side Entry allows easy access into the Avionics Bay Two switches with external, removable keys ¼” plywood sled holds two altimeters Plywood races guide altimeter sled into place and securely hold altimeters in place during flight. Volume of Altimeter Bay is 142 in³
12	Avionics Bay Construction and Function (Cont)
13	Avionics Bay Construction and Function (Cont) Function Configuration Fully Redundant Altimeter System Dual PF MAWD altimeters Dedicated Key Switch for each altimeter Dedicated battery pack for each altimeter Dedicated Drogue charge wires and Main charge wires for each altimeter Altimeter Settings Mach Delay: 8 seconds Drogue Charge: Apogee Main Charge: 700 feet Testing MAWD Altimeters each tested in homemade altitude chamber Verified apogee and proper drogue and main charge function Drogue and Main Parachute Ejection Charges fully tested in flight configuration Verified strong ejection (~10’ of separation, parachutes fully ejected from airframe)
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15	Recovery System Construction & Function Drogue Parachute System Drogue Parachute: B2 Rocketry Cert-3 Drogue (~24” dia) Drogue Harness: 5/8” tubular Kevlar, 60’ long 3/8” Quick Link at each end Drogue Parachute attached 10’ from forward end of Drogue Harness RocketHunter Transmitter electrical-taped to Drogue Harness Drogue Compartment Volume: 424 in³ Drogue Compartment held closed with 4 x #2-56 nylon screws Drogue Ejection Charge: 2.75 grams Generates 12.6 psi for an Ejection Force of 356 lbf Successfully ground tested on 5/28/2006 in flight configuration
16	Recovery System Construction & Function Main Parachute System Main Parachute: Rocketman R14C Drogue Harness: 5/8” tubular Kevlar, 30’ long 3/8” Quick Link at each end Main Parachute attached 10’ from forward end of Drogue Harness Main Chute Compartment Volume: 707 in³ Main Compartment held closed with 4 x #2-56 nylon screws Drogue Ejection Charge: 5.5 grams Generates 15.1 psi for an Ejection Force of 427 lbf Successfully ground tested on 5/27/2006 in flight configuration Main Chute deployed at 700’ Velocity at landing: 20 fps
17	Rocket Attributes Gross Liftoff Weight: 40 lbm Landing Weight: 33 lbm Stability (Calculated using RockSim 7.0) CP Location: 17.5” from base (RockSim Equation) 21.5” from base (Barrowman Equation) CG Location 39” from base (hand measured in flight configuration) Stability Margin 3 calibers (Barrowman CP) 3.6 calibers (RockSim CP)
18	Flight Predictions Predictions performed using RockSim 7.0 Rocket Attributes GLOW (w/ motor): 40 lbs Landing Weight: 33 lbs Motor: AMW M1350 Max Thrust: 1662N (373 lbf) Launch 44 fps achieved in 46” of travel Thrust/Weight: 9.3 Main Deployment Altitude: 700’ (pre-set) Velocity at deployment: 101 fps Landing Velocity: 20 fps
19	Concluding Remarks Excellent Structural Integrity Performance Rocketry Airframe, Fincan, Nosecone, Coupler Handmade Centering Rings and Bulkheads from ¾” Plywood CRs attached to Motor tube with 30-min epoxy, w/ generous fillets CRs and Bulkheads attached inside FG Airframe and Coupler with 30-min epoxy and 3 #8-32 screws (each). FG Fincan attached to FG Airframe w/ 30-min epoxy and six #8-32 screws. Motor retained by 3/8” threaded rod in forward closure Ample Stability Margin (at least 3 calibers in launch configuration) Robust Recovery System Fully Redundant Electronics Each of two altimeters has dedicated key switch, battery pack, drogue charge, main charge Both altimeters are PF MAWDs, which has high reliability Both altimeters have been individually tested in homemade altitude chamber Ejection Charges have been fully tested and provide excellent ejection force and approximately 10’ of separation during ground test and parachutes fully ejected from airframe. B2Rocketry Cert-3 Drogue Chute Rocketman R14C Main Chute Tubular Kevlar Harnesses (60’ for Drogue, 30’ for Main) 101 fps Drogue Descent Velocity is acceptable 20 fps Landing Velocity is acceptable for Manchester Field RocketHunter xmitter attached to Drogue Harness Good Motor for Hey Bubba 9.3 Thrust/Weight 8600 feet, predicted altitude Biggest Concern for this flight? Staying out of the trees!