John A. Sigmon NAR Level 3 Certification Package

Transcription

1 The Players John A. Sigmon, the applicant, NAR #96911 Robert DeHate, L3CC Scott Szympruch, package reviewer MAC Performance Radial Flyer, the rocket The Rocket The rocket is a MAC Performance Radial Flyer with a 75 millimeter motor mount tube. It was designed by Mike Crupe and sold as a kit. It is a standard 3FNC design with no unique features. Total length: inches from the tip of the nose cone to the bottom of the motor retainer. Diameter: four inches (4.023 inches outside). Components: Outside: Aero Pack 75 millimeter motor retainer, 46-inch canvas phenolic booster tube, one-inch canvas phenolic switch band, 20-inch canvas phenolic payload tube, 5:1 ogive Pinnacle polystyrene hollow nose cone with 19.5 inches exposed, and three canvas phenolic fins. Inside: a 16-inch XX phenolic motor mount tube, a 3/8-inch forward Baltic birch centering rings, a 1/4-inch Baltic birch middle centering ring, a stepped 3/8-inch Baltic birch thrust plate, an eight-inch XX phenolic coupler with two 3/8-inch stepped Baltic birch bulkheads. Component 46-inch booster tube 20-inch payload tube 8-inch coupler/avionics bay Pinnacle hollow nose cone with 5.75-inch shoulder Three fins Forward centering ring Middle centering ring Thrust plate (stepped) Avionics bay lids (stepped) Two rail buttons Material canvas phenolic canvas phenolic XX phenolic polystyrene polished canvas phenolic 3 /8 Baltic birch plywood ¼ Baltic birch plywood 3 /8 Baltic birch plywood 3 /8 Baltic birch plywood 1515 Delrin 1

2 Name Radial Flyer Flight configuration 5198-M1101-WH-P Length in Stability 1.74 cal Diameter in CG in Mass with motors 327 oz CP in Apogee ft Max. velocity 961 mph (Mach 1.26) Max. acceleration 470 ft/s 2 Text from OpenRocket Model (Above) The Motor The Finished Rocket The certification flight will utilize a CTI 5198M1101-WH-P motor. It is certified by the Canadian Rocketry Association in reciprocity with the National Association of Rocketry and the Tripoli Rocketry Association. It is a four-grain motor with CTI s white propellant, with a plugged forward end. The motor is an M-class, with 1111 Newtons of average thrust, yielding Newtonseconds of total impulse. 2

3 Construction The area between the middle and aft CRs will be filled with two-part foam; this reinforces the strength of the fin can without adding significant weight. Assembled using Bob Smith Industries 30-minute epoxy. The designer of this kit (Mike Crupe) only uses BSI 30-minute epoxy, and has done several transonic and supersonic flights with this construction method. He has formally recommended BSI 30-minute epoxy. The following pictures show internal construction details that will be invisible in the finished rocket. Forward centering ring with shock cord mount, top and bottom fillets. 3

4 Middle centering ring, top fillet. Internal fin fillets prior to filling with foam. 4

5 Fin can filled with two-part foam. The Recovery System The rocket will use redundant electronic deployment systems. 5

6 Finished AV bay Avionics: it will have a Perfect Flight Stratologger CF as the primary dual deployment controller, and a Missile Works RRC2+ as the back-up controller. These are barometric sensor altimeters. Each will be powered by a fresh 9-volt Energizer Max alkaline battery with 595 mah of current. The following illustration shows the wiring diagram for the electronics. 6

7 Avionics Wiring Diagram (not to scale) 7

8 Safety: dedicated rotary switches will control arming the devices; switches will be mounted through a 1-inch switch band around the avionics bay, with easy external access at the pad. Switches are screwdriver controlled. The Bay: the altimeters are mounted to a sled within the avionics bay on risers allowing ¼ of airflow between the altimeter and the riser for sensing purposes. The avionics bay is vented with three ¼ static ports for sampling. Devices and battery holders will be mounted to the sled via small machine screws, with standoffs for the altimeters. The avionics bay is sealed, and thus immune to hot ejection charge gasses. Operation: the primary altimeter will fire at apogee, deploying the drogue parachute. One second later, the back-up altimeter will also fire its drogue charge. At 700 feet, the primary altimeter will fire its main charge, deploying the main parachute. The back-up altimeter will fire at 500 feet. Three #2-56 nylon screws will be used as shear pins in the booster and the nose cone. Descent: I am using Top Flight Recovery, LLC's recommendation for a 58 octagonal parachute for a 9 12 pound rocket. The built-weight of the rocket is 9.6 pounds, and the motor s burnout weight is 4.1 pounds, which means descent under main is at 13.7 pounds. OpenRocket shows a ground-hit velocity of 18.2 mph (27.3 fps). I believe the construction of the rocket, foamed fin can, and slightly upswept fins can easily handle this rate. Parachutes: the drogue parachute is a Top Flight 18-inch ripstop nylon octagonal chute. The main parachute is a Top Flight 58-inch ripstop nylon octagonal chute. No deployment bags are required for these chutes. Shroud Lines: Top Flight Recovery s standard TFR line of parachutes use braided nylon for shroud lines. They are sewn into the canopy of the parachute. For the 18-inch drogue, there are six lines, 18 inches long and 1 /16-inch wide, with a breaking strength of 110 pounds. The 58-inch main has eight lines, 58 inches long and 1 /8-inch wide, with a breaking strength of 250 pounds. Mounting: the drogue parachute is mounted to the aft shock cord via a sewn loop; the main is attached directly to the nose cone. Quik-Links and swivels are used to attach the shroud lines to the shock cord (drogue) or nose cone (main). The Quik-Links also serve as a release mechanism. Staging: The booster tube serves as a drogue parachute bay, and the payload tube serves as a main parachute bay. Pyrotechnics: a total of four charge wells will be used to contain the black powder ejection charges, two on each end of the avionics bay, one on either end for each 8

9 altimeter. Standard electric matches are used for ignition, with a separate match for each charge well (a total of four). The chart below shows the amount of FFFFg black powder that will be loaded into each charge well. The referenced volumes will be measured using Lee Powder Spoons, available at gun shops. Charge Well Primary apogee separation Back-up apogee separation Primary main (nose cone) separation Back-up main (nose cone) separation Volume of BP 1.3 cc 1.5 cc 1.1 cc 1.3 cc Shear Pins: at a maximum acceleration of 14.8 G, the booster will require a retention strength of approximately 67.0 pounds-force (in the worst-case scenario of a sudden deceleration to zero at burnout). With a shear strength of between 36 and 45 pounds-force for one #2-56 nylon screw, it is evident that two shear pins are required to prevent drag separation. To retain the nose cone during apogee deployment, an estimation of 10.1 poundsforce is required. One #2-56 nylon screw will be efficient as a shear pin. The chosen ejection charges (see table above) are capable of breaking a maximum of five shear pins. Therefore, in order to align shear pins with the fins to minimize drag, three #2-56 x ¼ shear pins will be used in each section of the rocket, aligned with the fins. Shock Cords: the shock cords are comprised of 11 /32-inch tubular Kevlar, manufactured by Ted Chernok of One Bad Hawk. Each is 25 feet in length. Verification: Prior to the Level 3 certification flight attempt, the recovery system was tested on the ground to ensure that the calculated black powder charges were sufficient to separate the sections of the rocket, deploy the recovery system, and not cause the components to snap back on each other, causing damage to the rocket. Flight Expectations Launch weight 20.5 lb Estimated drag coefficient 0.53 Launch velocity prediction 58.3 fps Maximum expected velocity 1,440 fps Maximum expected altitude 11,987 feet Maximum expected acceleration 476 ft/sec 2 Expected risks none 9

10 OpenRocket was used to run the following simulation. It is based on an eight-foot launch rail at the Higgs Farm in Henderson, MD, with moderate winds (median 10 mph). Stability Evaluation The launch will be from the away pads at the Higgs Farm, on 1515 rail, ten feet long. OpenRocket has been used to calculate the CP (see the drawings above). The calculated CP is (or, roughly /32) inches from the nose cone tip. The measured CG (balance point) of the rocket is from the tip of the nose cone; OpenRocket predicted the CG would be from the tip of the NC. The simulation has been adjusted to override the CG to more closely match the measured value. Noting this, it is clear that the CG is sufficiently forward of the CP to ensure a stable flight while attaining Mach speeds, coming in at 1.74 calibers forward of the CP at launch. Since this is a standard shaped, 3FNC rocket, no additional calculations for CP are required, nor is spin-testing. However, since the rocket will reach speeds above Mach 1, the following stability ratio simulation was performed in OpenRocket: 10

11 Minimum Fineness and Fin Span:Thickness Ratios The NAR requires a minimum fineness ratio of 4:1. The rocket s length is inches. It has a constant tube diameter of 4 inches. This yields a 21.7:1 fineness ratio. For the fins, a minimum ratio of 4:1 is required between the fin s mean chord and its thickness, and also its semi-span and its thickness. Fin thickness is 3 /16 inches (or inches). For a 4:1 ratio, both the semi-span and mean chord would have to be at least 0.75 inches (4 x ). Since no measurement on the fins is anywhere near as low as 0.75 ( 3 /4) inches, the 4:1 minimum ratio is easily met. Safety Precautions At Home: the rocket will prepared at home prior to the launch date. This will include building and installing the motor, installing the ejection charges and connecting the avionics in the safed condition, packing the parachutes and shock cords, and continuitytesting the recovery system. Prior to Launch: since the certification flight will occur at a Maryland-Delaware Rocketry Association club launch, the rocket will be inspected by a Range Safety Officer. It will also be inspected by the L3CC and the flight witness. The rocket will not proceed to the launch pad until all reviewers are satisfied as to its safety. 11

12 At the Pad: the rocket will be inserted into a 1515 rail on an away cell. It will be raised to the vertical position, conforming to all NAR High Power Safety considerations as to launch angle, distance from spectators, etc. After the rocket is vertical, the primary avionics system will be activated, followed by the secondary system. The igniter will be inserted into the nozzle of the motor, and then the launch controller leads will be attached to the igniter wires as the final step. Launch: a Launch Control Officer will announce that it is a certification flight, alert the spectators that the launch is commencing, and give a countdown prior to ignition. Recovery: the rocket will be tracked with a Big Red Bee BRB900 GPS tracking device. Once the rocket is on the ground and the Launch Control Officer has safed the pads, I will recover it and present it to the L3CC and flight witness for inspection. The motor will not be touched or removed until it has had adequate time to cool. 12

13 Checklists PRE-LAUNCH: Electronics: Wire avionics in according to the specifications in this document Test continuity of electronic matches and avionics systems Ensure switches are safed Load specified amounts of black powder into charge wells for primary and back-up Insert electronic matches into charge wells and ensure contact with black powder Top off charges with dog barf and compact; apply masking tape to secure Assemble avionics bay lids Rocket: Construct rocket according to the specifications in this document Motor: Build motor and install in motor casing Attach parachutes via Quik-Links and swivels Secure shock cords to booster, AV bay coupler, and nose cone via Quik-Links Protect drogue parachute and load into booster tube Protect main parachute and load into payload tube Measure and note actual center of gravity and compare to simulation Ensure fins are firmly attached Build motor to manufacturer s specifications Make sure all parts have been installed and accounted for Slide reload into motor casing and apply closures Insert motor into motor mount tube Leave igniter out of the motor until on the pad LAUNCH: Fill out launch card, indicating that this is a Level 3 certification flight Present flight-ready rocket to RSO, L3CC, and flight witness for inspection Carry rocket and the following tools to the launch pad: Level for determining launch angle A-clip to act as a temporary rail stop for igniter insertion Masking tape in case the igniter is loose, or to wrap igniter leads to clips Multi-tool for arming avionics, stripping wires, etc. Attach A-clip to launch rail Lower launch rail and insert rocket; slide down to A-clip Raise and secure the launch rail 13

14 Checklists Arm each avionics system and check for continuity and battery voltage Insert and secure the igniter Remove A-clip and lower rocket to the rail stop Take flight card to the LCO table POST-LAUNCH: Locate landing coordinates via GPS transmitter Recover the rocket Leave motor inside rocket Present rocket to the L3CC and flight witness for inspection IN CASE OF LAUNCH FAILURE: Wait until the LCO has declared the range safe, then proceed to the launch pad Disconnect and remove the igniter Safe the avionics systems Remove the rocket from the pad 14