Recovery System Components and Operation

A. Description of Operation

At 300 feet AGL as detected by the Missile Works altimeters the ejection system will arm. At apogee (approximately 3800 feet) the pyrotechnic charges in the nose will fire ejecting the nose cap into the airstream which, until now, has been held in place by friction and air pressure. The nose cap will deploy a 48 inch parachute and pull the deployment bag for the 9 foot drougue/nose cone chute from the nose cone. The chute, attached to the nose cone with a 15 foot 9/16 inch tubular nylon shock cord and quick links, will open allowing a controlled descent at approximately 33 ft/sec to 800' AGL. At 800 feet AGL the main chute charges will fire, shearing the 6 4-40 nylon screws holding the nose cone to the booster. The nose cone will pull away from the booster section pulling the deployment bag for the main chute. The 15 foot main chute, attached to the booster section with two 25 foot 1 inch tubular nylon shock cords and quick links, will deploy and gently bring the booster section to earth at approximately 17 ft/sec. The nose cone and nose cone chute now free of the weight of the booster will slow and gently descend to earth as well at approximately 16 ft/sec.

B. Description of Components

1) Control Device #1 - Missile works RRC2 Altimeter.

• a) Arming Method - Barometric, 300 foot minimum altitude detection.
• b) Power Supply - Attached 9V Alkaline battery.
• c) Safe and Arm controls - Battery disconnect connected to a normally closed phono jack; removing a phone plug applies battery power to the altimeter. Additionally, dual pyrotechnic channels are safed and armed through normally closed phono jacks as well; removing the phono jack allows continuity for the pyrotechnic charges.
• d) Altimeter Mounting - 4 - 4X40 screws to electronics bay #1 mounting pad.
• e) Wiring schematic - see below

2) Control Device #2 - Missile works RRC2 Altimeter.

• a) Arming Method - Barometric, 300 foot minimum altitude detection.
• b) Power Supply - Attached 9V Alkaline battery.
• c) Safe and Arm controls - Battery disconnect connected to a normally closed phono jack; removing a phone plug applies battery power to the altimeter. Additionally, dual pyrotechnic channels are safed and armed through normally closed phono jacks as well; removing the phono jack allows continuity for the pyrotechnic charges.
• d) Altimeter Mounting - 4 - 4X40 steel screws to electronics bay #2 mounting pad.
• e) Wiring schematic - see below.

3) Parachutes

• a) The drogue/nose cone parachute is a homemade semi-sphere with a diameter of 9 feet. It was built from 1.5 oz. ripstop nylon with 8 - 1/2 inch tubular nylon shroud lines running full length across the top of the canopy. The shroud lines extend 9 feet below the canopy and are connected to a 1000 lb test swivel.
• b) The main parachute is a military surplus 15 foot diameter flare chute with nylon shroud lines. The shroud lines terminate into two separate riser assemblies which are attached together with a quicklink. The Main is attached to dual main body shock lines with a 1000lb swivel and a quick link.
• c) The nose cap parachute is a 48 inch sperachute attached to a 12 foot 9/16 inch nylon shockcord with a quicklink.
• d) The deployment bag for the main is XLarge Rocketman kevlar deployement bag and is attached to the nose cone through a 1 inch nylon strap and a quick link. The deployment bag for the drogue/nose cone parachute is a large Rocketman kevlar deployment bag and is attached to the nose cone with a 1 inch nylon strap and a quick link.

4) Risers

• Main Chute:

• a) 2 - 1 inch wide tubular nylon shock cords, 25 feet long with a breaking strength of 4000 LBS TEST(MIL(C)SPEC 5625)
• b) Loops at each end are sewn with heavy duty thread and a cross stitch pattern. The shock cords were bought from Giant Leap Rocketry.



• Drogue/Nose Cone Chute:

• a) 1 - 1 inch wide tubular nylon shock cord, 15 feet long with a breaking strength of 2000 LBS TEST(MIL(C)SPEC 5625) attached between the nose cone and chute.
• b) Loops at each end are sewn with heavy duty thread and a cross stitch pattern. The shock cords were bought from Giant Leap Rocketry.



• Nose Cap Chute:

• a) 1 - 9/16 inch wide tubular nylon shock cord, 12 feet long with a breaking strength of 1500 LBS TEST(MIL(C)SPEC 5625) attached between the nose cap and chute.
• b) Loops at each end are sewn with heavy duty thread and a cross stitch pattern. The shock cords were bought from Giant Leap Rocketry.

5) Mounting hardware

• Main Chute

• a) The main chute is attached at two separate points within the airframe. Two 3/8 inch diameter U-bolts were bonded to the upper centering ring during contruction. Steel washers and nuts were used on both sides of the U-bolts. 3/8 inch threaded steel rods connect the upper and middle centering rings effectively spreaded the main chute load throughout the entire airframe.
• b) 5/16 inch (1540 lb test) quick links are used at both the connection with the U-bolts and with the swivel at the main chute.
• c) The deployment bag for the main chute is attached to an 3/8 inch eyebolt attached to the bottom of the nose cone. At 800' AGL the pyrotechnic charges will fire, shearing the nylon shear bolts and separating the nose cone from the main airfarme. The deployment bag will stay with the nose cone while the main chute and booster will descend together.



• Drogue/Nose Cone Chute

• a) The drogue/nose cone chute is attached to a 3/8 inch steel eyebolt in the nosecone.
• b) 1/4 inch (660 lb test) quick links are used at all three connections in the nose area.
• c) At apogee the pyrotechnic charge will fire causing separation between the nose cap and nose cone. The nose cap will pull the deployment bag out of the nose cone and deply the drogue/nose cone chute.



• Nose Cap Chute

• a) The nose cap chute is attached to a 3/8 inch steel eyebolt in the nosecap.
• b) 3/16 inch (300 lb test) quick links are used at all connections in the nose area.
• c) At apogee the pyrotechnic charge will fire causing separation between the nose cap and nose cone. The nose cap will pull the deployment bag out of the nose cone and deply the drogue/nose cone chute as well as its own 4 foot spherachute.

6) Pyrotechnic devices

• Main Chute:

• a) There are two pyrotechnic charges for the main chute deployment for redundancy. Each charge is installed in a 1" PVC threaded cap which screws into the receptacle in the main airframe.
• b) The charges will be ignited with an electric match.
• c) 3.5 grams of FFFFg black powder was used in each charge.
• d) The charge weight was calculated based on the volume for the area under the nose cone and the force required to generate 210 lbs of force to shear the 6 4-40 nylon screws plus an additional 100lbs to eject the nose cone.



• Drogue/Nose Cone Chute

  :
• a) There are two pyrotechnic charges for the drogue/nose cone chute deployment/nose cap deployment for redundancy. Each charge is installed in a 3/4" PVC threaded cap which screws into the receptacle in the nose cone.
• b) The charges will be ignited with an electric match.
• c) 1.5 grams of FFFFg black powder was used in each charge.
• d) The charge weight was calculated based on the volume under the nose cap and a total pressure of 200lbs.

C. Recovery Sequence Initiation Device Testing and Operation Verification

• 1) Altimeter Tests

The RRC2 Altimeter has 2 test modes: Test Mode #1 called input test mode allows testing of the input selectors on the altimeter and continuity testing of the charges. Test Mode #2 called output testing tests the actual firing mechanism including ignition of the electric matches.

• 1. Attach the wires from the phono jack with phono plug installed to the J3 terminals on the altimeter.
• 2. Attach one of the wires from the phono jack with phono plug installed to one of the terminals on the J2 terminals on the altimeter. Repeat with J1.
• 3. Attach the other wire from the phono jack with phono plug installed to a lead of an electric match. Repeat with the other phono jack.
• 4. Finally, attach the remaining lead from the electric match to the remaining terminal on J2. Repat with J1.
• 5. To Test, place all switches in the 'ON' position and remove the phono plug from the phono jack leading to J3, this arms the altimeter. Cycle switch #1 during power on which puts the altimeter into Test Mode #1. The Altimeter will beep 5 times to indicate all the switches are in the 'ON' position and no continuity is detected in the electric matches.
• 6. Repeat the test, except remove the phono plugs from the jacks leading to the electric matches; this provides continuity to the circuit. The altimeter should beep 7 times.
• 7. To test the electric matches, remove the phono plugs from the phono jacks leading to the electric matches. Remove the phono plug from the phono jack attached to J3, this arms the altimeter. During power on, cycle switch #2 which puts the altimeter into output tset mode.
• 8. The altimeter should beep 5 times a second for 10 seconds then fire the electric match at J1; J2 should fire imediately after J1.



• 2) Ground Tests:

• 1. The booster section was vertical; I assumed this would be the worse case having to lift the nose cone and shear the screws.
• 2. The lead wires from an Estes Launch Controller was run up a motor tube into the booster section.
• 3. The motor tubes were sealed with duct tape.
• 4. The pyrotechnic charge was screwed into the holder in the booster section.
• 5. The leads from the launch controller were coneccted to the charge and taped.
• 6. The nose cone was secured to the booster section with six 4-40 nylon screws.
• 7. The arming pin was installed in the Launch Controller to check for continuity.
• 8. The launch button was pushed, the charge fired and the nose cone cleanly separated from the booster section.

Descent Calculations

• Main Chute

The calculations for the main chute were done using the descent calculator on the Rocketry Online Forum. The military surplus parachute has an width of 15 feet. With a weight of 63 lbs the rocket on a 15 foot parachute will have a descent rate of 17 ft/sec.

• Drogue/Nose Cone Chute

The calculations for the drogue/nose cone chute were done using the descent calculator on the Rocketry Online Forum. The homebuilt parachute has an width of 9 feet. With a weight of 83 lbs the rocket on a 9 foot parachute will have a descent rate of 33 ft/sec. After separating from the booster at 800 ft agl the nose cone will have a weight of 20 lbs and a descent rate of 16 ft/sec