ESA Document - Emits - ESA

s
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 337 of 422
Due to the high mass of the MEV, a vehicle with good drag coefficients to reduce the velocity
and relatively good lifting coefficients is necessary to achieve the requirements and specially the
terminal velocity and g-load.
4.4.2.2 Assumptions and trade-offs
Different shapes have been studied as a bent biconic shape (Figure 4-75), biconic blunt body as
well as IBD model (Inflatable Braking Device) (Figure 4-76). First analysis showed that the
MEV should have a reference surface greater than 300 m 2 .
Figure 4-75: Bent biconic shape
Figure 4-76: IBD shape
The IBD shape was preferred due to the reduced volume of the device during the launch. Three
IBD shapes have been proposed corresponding to three cone angles (Figure 4-77): 45˚, 60˚ and
70˚half cone angle. Reference lengths and surface are reported in Table 4-38 shown.
Figure 4-78 shows IBD shapes that have been realised around a cylinder of 6 m diameter and 12
m long, representing the SHM and the MAV.