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