Responsive Access Small Cargo Affordable Launch (RASCAL ...

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types. Each fuel fraction is defined as the ratio of end weight to beginning weight. Fuel fractions for mission segments 1-3 and 9-12 were used as static historical values. While the remaining fuel fractions have been calculated using historical equations using aircraft characteristics. These equations are given below for the climb, cruise, and loiter portions of the mission profiles E cl cl = ( 1/ c j ) cl ( L / D) LN( ff ) (2) R j cr cr ( V / c ) ( L / D) LN( ff ) cr = (3) E j ltr ltr ( 1/ c ) ( L / D) LN( ff ) ltr = (4) From these equations and the historical constants the calculated mission fuel fractions are given in Table 4. Table 4: Mission Fuel Fractions. 1 FF Engine Start 0.9900 2 FF Taxi 0.9900 3 FF Takeoff 0.9900 4 FF Climb 0.9714 5 FF Cruise out 0.9596 6 FF Loiter 0.9624 8 FF Cruise In 0.9295 9 FF Descent 0.9900 10-12 FF Landing 0.9950 With these fuel fractions the entire fuel consumed in the aircraft portions of the trajectory can be calculated. Launch Vehicle Trajectory: The second portion of the trajectory is the launch vehicle portion. This is the part of the trajectory which is unique to the RASCAL design. Because of the uniqueness of the trajectory POST was used to calculate the optimized trajectory. POST is a three dimensional trajectory optimization code which takes inputs from the propulsion, weights, and aerodynamics disciplines and simulates the trajectory of the spacecraft subject to the performance constraints listed in Table 5. 20
Table 5: POST Trajectory Constraints. Max Axial Acceleration 6 g's Max Dynamic Pressure 2000 psf Max Angle of Attack 20 degrees Max Dynamic Pressure at Release 1 psf Final Orbit Apogee 270 nmi Final Orbit Perigee 270 nmi Final Orbit Inclination 98 degrees Due to the complexity of the RASCAL trajectory the airbreathing, and rocket portions of the trajectories were calculated separately to get approximate “guesses” for the combined trajectories. These outputs with their appropriate initial conditions are then combined into one POST input file which is then optimized to minimize the propellant consumed by the stages. The first stage input deck was set up to use the MIPCC engines as defined in the propulsion section. This input file starts with an initial weight, accelerates the aircraft until an appropriate time when the aircraft begins the zoom maneuver. This zoom maneuver involves increasing the altitude while still firing the MIPCC engines. Once the aircraft reaches the MIPCC limits of 88,000 ft and Mach 4 the engines shut down. The aircraft then continues to gain altitude by trading kinetic energy for potential energy. The first stage then coasts until the flight path angle drops to 20 degrees (other flight path angles were used, but 20 degrees results in the smallest vehicle). The first stage input deck actually tries to maximize the velocity of release to give the second stage as much energy as possible. The dynamic pressure constraint of release combined with this optimization scheme also results in an altitude in excess of 200,000 ft at release. Once the first stage is optimized the second stage begins at the altitude, velocity, azimuth, latitude, longitude, and flight path angle of the end of the first stage. The second stage ignites after a coast of 5 seconds after release from the aircraft to get a significant distance between the stages. The second stage hybrid then ignites until the ideal ∆V provided by the second stage reaches 11,000 fps. This ∆V number was set in the RASCAL design, but it was traded and found to be close to the optimal point. After the second stage falls away the third stage ignites after a five second delay. The third stage then fires until the proper orbit is reached. The entire upper stage input file is designed to optimize the weight consumed. The final weight at the end of the run is then 21
Page 1 and 2: Responsive Access Small Cargo Affor
Page 3 and 4: List of Figures: Figure 1: Launch C
Page 5 and 6: Abstract: RASCAL is a Defense Depar
Page 7 and 8: Introduction: Due to the uncertaint
Page 9 and 10: This stage will then propel the veh
Page 11 and 12: stages which continue on to orbit.
Page 13 and 14: driving constraint) will then be fl
Page 15 and 16: Once the geometry is defined it mus
Page 17 and 18: Coefficient of Drag 0.6 0.5 0.4 0.3
Page 19 and 20: These characteristics were then ana
Page 21 and 22: To analyze the effect of MIPCC an A
Page 23 and 24: 14. The new Isp of the MIPCC engine
Page 25: combination selected the overall we
Page 29 and 30: Thrust (lbs) 120000 100000 80000 60
Page 31 and 32: Gross Gross Weight Dry Dry Weight W
Page 33 and 34: Temperature (F) 1400 1300 1200 1100
Page 35 and 36: Operations: Number 1st Stages 5 Num
Page 37 and 38: Cost Estimation: The cost estimatio
Page 39 and 40: As this figure depicts the DDT&E fo
Page 41 and 42: profile of the cost charts is due t
Page 43 and 44: Each of these alternatives will be
Page 45 and 46: 1+2+3 1+3 4th Stage MMC 1st Lox Hyb
Page 47 and 48: The design alternatives were costed
Page 49 and 50: GT RASCAL: From this alternative an
Page 51 and 52: As this figure shows the GT RASCAL
Page 53 and 54: used in the GT RASCAL design is in
Page 55 and 56: Figure 39: GT RASCAL Mission Profil
Page 57 and 58: When the final cost numbers of the
Page 59 and 60: References: 1. Cyr, Kelley, “US L

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