Engineering Project PortfolioDEREK OUNG

Due to longer coast times on Falcon Heavy missions, the S2 Pneumatics Regulator must withstand colder temperatures than the current design can. The S2 Pneumatics Regulator regulates Helium gas from 5500 psia in the Helium tanks upstream to about 800 psia for the pneumatics system downstream, which includes volume and flow rate demands.

Replaced the Elastomer O-ring seals with spring-energized Teflon seals that can seal at lower temperatures. However, the dynamic seals now have a higher coefficient of friction due to the material change. This exacerbates the hysteresis of the valve to an unacceptable level (The downstream pressure at the same downstream flow rate demand is too different depending on whether the poppet was coming from a more closed position or a more opened position)

Modeled the hysteresis behavior and underlying physics of the S2 Pneumatics Regulator with MATLAB. Used this model to understand what the temperature dependent coefficients of frictions are and what the frictional force is for an acceptable level of hysteresis as well as how a change in pressure area changes the frictional force if the regulator is redesigned.

Tested the S2 Pneumatics Regulator with elastomer O-ring seals and Teflon seals with and without lubrication at different temperatures and pressures to improve and validate MATLAB model.

Development effort saved the need for a major redesign and requalification. Regulators with lubricated spring-energized Teflon seals were tested to required temperatures and functioned as intended. Falcon Heavy will be flying with these regulators.

SpaceX: Falcon Heavy Stage 2 Pneumatics Regulator Development

SpaceX: Falcon 9 and Falcon Heavy S1 and S2 Pneumatics Regulator Design Upgrades

Design Upgrades were made for Falcon 9 S1 and S2 Pneumatics Regulators in order to increase flight and build reliability for implementation during the final Falcon 9 Block Upgrade

Redesigned spring retainers to reduce pressure setpoint drifting, spring wear against the spring cap inner wall and friction due to poppet off-axis loading, which causes hysteresis and reduced valve life

Redesigned coil springs for appropriate minimum tensile strength and maximum percent deformation to increase spring fatigue life

Redesigned S1 pneumatics regulator poppet assembly to eliminate galling between the poppet assembly and the regulator body.

Redesigned various features of regulator parts to simplify the assembly process and eliminate assembly mistakes caused by human error

SpaceX: Falcon 9 Stage 2 Pneumatics Regulator Seat Press Development

Seats (Brown part in picture to the left) were coming in from suppliers with poor quality, causing through leakage in theregulators. This causes the downstream pressure to be higherthan designed for the system downstream duringlockup (no downstream demand).

Designed seat press development assembly tooling (all parts are outsourced) to study the relationship between seat load, seat deformation and leakage at different temperatures and pressures. If deforming the seat can overcome quality issues and decrease leakage, it can be implemented as standard procedure for all seats.

Performed hand calculations for fasteners and finite element analysis with Ansys to ensure that seat press development tooling is man safe (does not require additional containment at maximum expected operating pressure)

Modeled the physics of the interaction between seat load and seat deformation with MATLAB. This model was used to determine what the maximum load and travel are required for the setup.

Poppet travel is designed to be controlled by using a bolt and enlarged washer where the bolt hole on the poppet is. This limits maximum seat deformation regardless of load in order to study the relationship between deformation and leakage in addition to the relationship between load and leakage.

Poppet

Seat

BodyCap

Seat RetainerSeals

Inlet

Outlet

SpaceX: Falcon 9 Full Thrust (v1.2) Pre-valve Qualification CampaignPre-valve design for Falcon 9 Full Thrust needed to be qualified. Pre-valves are quarter turn (90 degrees) isolation butterfly valves that isolate or connect RP-1 kerosene and Liquid Oxygen (LOX) from their respective tanks to the Merlin Engines on both Stage 1 and 2.

Designed, scheduled, executed and documented qualification test campaign for F9 Full-Thrust Pre-valves with SMC-S-016 (Air Force Space Command Space and Missile Systems Center Standard Test Requirements for Launch, Upper-Stage and Space Vehicles) as primary guideline

Design includes test setups, test procedures, test requirements and what data is collected and how

Schedule ensures that qualification campaign is completed 2 weeks before F9 Full Thrust launch. This includes planning appropriate duration for every step in the qualification campaign and potential schedule slips in addition to coordinating with the vibration lab and Texas test group for testing times as well as with dynamics and thermal groups for vibration and thermal levels.

Execution includes building test setups, implementing test procedures and collecting data.

Documentation includes data processing and a formal report of the qualification test plan and results

Coordinated with dynamics, thermal and Texas testing groups

Qualification Tests include thermal cycle, dry life cycle, wet life cycle, vibration, pressure cycle, burst pressure and performance tests

Pre-valves were qualified to fly on F9-21 within deadline. F9-21 was the first rocket SpaceX landed and recovered successfully!

Formula SAE: NFR 2015 Wheel CentersThe wheel center is connected to the hub on the inboard side ofthe car and the rim on the outboard side of the car. It transmits the loads from the car through the hub to the wheels through its attachment to the rim and vice versa, allowing the car to accelerate, brake and turn.

Designed and manufactured wheel centers to withstand up to 500 hours of track conditions for NFR 2015

Analyzed wheel center loading conditions, including torque, fatigue, shear stress and Euler buckling calculations

Conducted constraint force, static stress, deformation, frequency and buckling simulations using Hypermesh, Femap, Nastran and Solidworks under remote loads

Performed iterative calculations for optimal fastener locations (least weight) with MATLAB

Utilized Hypermesh and Optistruct to estimate geometry that optimizes weight and withstand stress and deformation requirements

Machined 4 wheel centers using Computer Numerical Control (CNC) milling with tool path generated in NX

Formula SAE: NFR 2014 Steering System

The steering system enables the driver to control the direction of movement of the car

Designed, manufactured and assembled the steering system for NFR 2014

Improved driver ergonomics by increasing theincline of the steering wheel and limiting thesteering wheel turn to 180°. The latter is done byselecting rack and pinion (bought) steering ratio and implementing positive steering stops at appropriate rack travel distances

Minimized the amount of play (unresponsiveness) in the steering system

Performed torsional shear stress calculations for the steering columns

Implemented progressive steering, where wheels turn more responsively as the steering wheel turns towards its limits, using the relationship between the ratio of input shaft velocity to output shaft velocity and rotation angle of a universal joint

Rack and Pinion

Steering Column Supports

Steering Columns

Steering Stops