SAWE Report - Cal Poly San Luis Obispo

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Another area of concern is that of visual observability. This is not a very big problem as the aircraft cruises so high that visually detecting the Vendetta would be near impossible. The only threat here is the contrails left by the engines. The contrails can be minimized by contrail avoidance techniques and don’t pose a large problem. To quantitatively analyze the radar cross section of the Vendetta, Radbase2 software by Surface Optics was utilized. First, a faceted model was generated from the 3D model. Faceting was limited to only those necessary because of the demanding processing requirements. Facets were limited to 10 degree tolerances at roughly 0.017 feet minimums. The facetted model is presented as Figure 4.2. Figure 4.2 - RCS Model Faceting It can be seen that heavy facet optimization was needed to make sure that all facets followed tangency requirements to leave smoothly curved and splined surfaces. The spline arc on the top of the fuselage is modeled with facets every 10°. For the flat surfaces like the wings and empennage 10° is more than adequate. The Radbase2 RCS code calculates the radar returns based on Physical Optics and Chu-Stratton integral methods. These are highly computationally intensive. Because of this, bounces off of surfaces were limited to 2 after the initial bounce off the surface. This was deemed adequate for this level of analysis. The vertical-vertical polarization of the return and transmission was analyzed as it is the most relevant to how radar stations operate. Monostatic radars which both broadcast and receive were used in the analysis as there would be too many possibilities to calculate for bistatic radars. The code was allowed to iterate on the model with 1° azimuth increments and for 0° and 15° lookup angles. It was also run for 1, 5, 10, and 12 GHz radar frequencies. Most fast track and search radar runs at the higher frequencies while long range threat radars utilize the lower frequencies. The 1 to 10 GHz range covers most of the radars that are expected for the role of this aircraft. A table of common ground and surface radars with their respective frequencies is presented as Table 4.I. 17
Table 4.I - Common Ground Radars Radar Manufacturer Frequency Image AN/TPS-43E Mobile Radar Westinghouse 2.9 to 3.1 GHz AN/TPS-70 Fixed Ground Radar Northrop Grumman 2.9 to 3.1 GHz AN/SPS-49 Typical Long Range Naval Radar Navy Research Labs 850 to 942 MHz AN/SPS-55 Long Range Surface Search Radar ISC Cardion 9.05 to 10.0 GHz Data is not readily available for radars made by foreign manufacturers. However, these radars should be adequate for this level analysis because the properties for radar waves traveling through the air over long distances are similar. The 1 to 12 GHz range covers FM and XM radar bands which are most common threats. The RFP specifically requires that the Vendetta has a frontal RCS of 0.05 m 2 . As the threat chart shown in Appendix A shows, most threats will be from below and at shallow angles of about 15° while at 50,000 during ingress. Because of this, the 0° and 15° lookup angles were analyzed. The results of the Radbase2 software are illustrated first in Figure 4.3, which depicts the radar cross section of the aircraft from a frontal, or 0° lookup angle. 18
Page 1 and 2: SAWE Paper No. 3232 Category No. 10
Page 3 and 4: Table of Contents Abstract_________
Page 5 and 6: List of Figures Figure 1.1 - Design
Page 7 and 8: Figure 13.4 - Rectilinear Vision Pl
Page 9 and 10: Nomenclature AIAA American Institut
Page 11 and 12: α Angle of Attack, degrees, rad.
Page 13 and 14: Table 1.II - Summary of Design Requ
Page 15 and 16: Figure 1.3 - F-15 Strike Eagle F-11
Page 17 and 18: Table 1.III - Comparison of the F-1
Page 19 and 20: Many of the equations buried in the
Page 21 and 22: 3 Configuration The current configu
Page 23 and 24: Another problem arises from the 20
Page 25 and 26: • Span = 54.7 ft • m.a.c. = 32
Page 27: 4 Stealth Considerations As mention
Page 31 and 32: 30 20 10 0 -10 -20 -30 -40 -50 1 GH
Page 33 and 34: 5 Aerodynamics The major aerodynami
Page 35 and 36: 1 GHz. 40º LE Sweep 10 GHz. 40º L
Page 37 and 38: 5.3 Wing Thickness The effect of wi
Page 39 and 40: 5.4 Airfoil The NACA 65A-003 airfoi
Page 41 and 42: 1 Section Lift Coefficient 0.9 0.8
Page 43 and 44: 90 80 Wing Cross Sectional Area (ft
Page 45 and 46: 6 Propulsion In developing the prop
Page 47 and 48: Table 6.II - RFP Dimensions Compare
Page 49 and 50: 38 Figure 6.1 - VAATE Goals
Page 51 and 52: TSFC 3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.
Page 53 and 54: Deflection Angle Analysis for Mach
Page 55 and 56: Figure 6.8 - Cost Association with
Page 57 and 58: The inlet has a boundary layer dive
Page 59 and 60: 7 Materials and Structure The overa
Page 61 and 62: Vertical Attachment Points Horizont
Page 63 and 64: 8 Landing Gear Landing Gear design
Page 65 and 66: steel. This means that more braking
Page 67 and 68: Table 9.II - Final Component Weight
Page 69 and 70: throughout the 5-hour mission. Usin
Page 71 and 72: 10 Stability and Control To initial
Page 73 and 74: difference in neutral point and cen
Page 75 and 76: 40 30 20 10 0 -10 -20 -30 -40 -50 2
Page 77 and 78: The Vendetta configuration utilizes
Page 79 and 80:
-0.6 -0.4 UNSTABLE NEUTRAL -0.2 Lif
Page 81 and 82:
Validation of an aircraft design su
Page 83 and 84:
consumption. The main aspects of th
Page 85 and 86:
In addition to the performance requ
Page 87 and 88:
70,000 Altitude (ft) 60,000 50,000
Page 89 and 90:
11.4 Mission Requirements By comple
Page 91 and 92:
Table 11.VIII - Landing Flight Prof
Page 93 and 94:
11.7 Alternate Missions In addition
Page 95 and 96:
12 Payload Weapon internal layout d
Page 97 and 98:
13 Cockpit Cockpit Design began wit
Page 99 and 100:
that could be used in landing and t
Page 101 and 102:
14 Systems The systems of the Vende
Page 103 and 104:
14.3 Fuel System Initial fuel syste
Page 105 and 106:
15 Manufacturing Several manufactur
Page 107 and 108:
16 Cost Analysis The final and perh
Page 109 and 110:
Appendix Threats Chart Common Surfa
Page 111 and 112:
Wing Break Point Fuel Aft Fuselage
Page 113 and 114:
The Vendetta Design Team Chris Atki
Page 115 and 116:
References 1. “Ejection Systems,
Page 117:
35. www.dfrc.nasa.gov/PAO/PAIS/HTML
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SAWE Report - Cal Poly San Luis Obispo

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