Responsive Access Small Cargo Affordable Launch (RASCAL ...

Once the geometry is defined it must be analyzed to produce the aerodynamic
coefficients necessary for the trajectory simulation. To analyze the aerodynamics
historical data was used for the subsonic and transonic analysis Hypersonic Arbitrary
Body Program (HABP) for was used for the hypersonic analysis. The historical data for
subsonic and transonic analyses was obtained from F-14 design data [3]. This data
contains the lift and drag coefficients as a function of Mach number and angle of attack.
These coefficients were taken at a wing sweep of 55 degrees (that of the RASCAL
design). The aerodynamic forces are then scaled by the coefficients and the RASCAL
wing area of 2700 ft 2 . This data was then combined with the HABP hypersonic analysis
to create a complete the aerodynamic data for both the first stage and the upper stages of
the RASCAL design.
The first aerodynamic data presented is the effect of Mach number on the zero lift
drag coefficient (CD0) (Figure 6). As this plot depicts the drag is highest for the first
stage at a Mach number of 1. The drag then decreases until Mach three and levels off.
The ramp up to Mach 1 is an effect of the transonic drag in this region. This abrupt
increase in drag can also be attributed to limited number of points before Mach 1 in the
F-14 design data. This plot was not carried out for higher Mach numbers because the
first stage will never achieve speeds in excess of Mach 4 (MIPCC cutoff speed).
The next set of data is the lift curve slopes for the first stage of the RASCAL
design (Figure 7). These again are a compilation of both the F-14 data and the HABP
analysis. As expected as the angle of attack increases the lift increases. Also as the
Mach number increases the coefficient of lift decreases (The actual lift increases, but the
coefficient is normalized by velocity squared).
The final set of aerodynamic data included is the drag polars (Figure 8). These
drag polars relate the total drag (induced and zero lift) to the lift produced. The lift
produced is a function of angle attack and Mach as depicted in Figure 8. Therefore given
angle of attack and speed (Mach) of the vehicle all of the aerodynamic properties of the
vehicle can be calculated.
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