Vendetta Final Proposal Part 1 (3.4 MB) - Cal Poly

4 Stealth ConsiderationsRadar cross-section (RCS) is an important low observability consideration for the Vendetta. The geometricshaping of an aircraft is the main contributor to its radar return. When radar energy interacts with the surface of anaircraft many phenomenon affect the resulting disturbance to the electromagnetic energy. Radio waves that strike asurface may reflect off of that surface or begin to travel along the surface. When edges are encountered, energy is eitherradiated outward in planes perpendicular to the edge or reflected back along the surface. To achieve low radar crosssectionin any particular aspect of an aircraft, the surfaces of the aircraft must be shaped so that the electromagneticenergy is either absorbed, or reflected away from the receiving station. After shaping, radar absorbing materials (RAM)can be utilized to minimize the spikes created by problem areas such as inlets, wing tips, and control surfaces.The design features described below and illustrated in Figure 4.1 are used to control the radar returns in specificaspects. The fuselage is constructed from flat sides and constant radius curves to produce radar returns in a singledirection away from the source of the radar energy. The sides are kept at a 60° angle from the horizontal and the bottomis kept flat to minimize the radar footprint that is created below the aircraft. The vertical tails are canted to avoidcreating perpendicular surfaces which would return radar energy directly back to its source. The leading edge sweep is40° creating spikes well off of the frontal aspect of the aircraft. All other leading edges are kept swept at this same angleto concentrate radar energy into the same regions. An analysis of radar threats, as shown in Foldout 3, indicates thatmost Vendetta will require low signatures from frontal aspect required by the RFP to a 15° look up angle.The RFP specifies that the aircraft incorporate balanced observables. Infrared (IR) sensors present anotherobservability threat. Emissivity matching will be employed to minimize the infrared energy radiated from hot surfaceson the aircraft. Specially designed paints and surface treatments will be used to match the emissivity of the aircraft tosurroundings, aiding in the disappearance of the aircraft to any IR sensors. As will be shown in the propulsion section, a40° LE SweepAll other SurfacesMatchedHidden CantedVerticalsFigure 4.1 - Stealth Considerations60° Facet13