SAWE Report - Cal Poly San Luis Obispo

6 Propulsion
In developing the propulsion system for the Vendetta, the RFP specifications of supersonic cruise
and stealth are the driving factors for the propulsions system. Due to the stealth criteria the fan
blades of the engine must remain hidden which drives the engine placement inside the airplane.
That combined with the supercruise criteria leads to four major aspects of the propulsion system:
the Engine, Inlets, S-ducts and Nozzles.
6.1 Engine Selection
The RFP specifies that the airplane should perform the mission with adequate installed thrust. A
Low-Bypass-Ratio Turbofan (LBR-TF) or a Turbojet (TJ) engine may be used to perform the
mission. Equations are provided for creating an engine deck, they are as follows:
LBR-TF:
TJ:
ρ
Tdry
= 0.9 TSL −dry
(0.88 + 0.24 ABS( M − 0.6) )( )
ρSL
2 ρ 0.8
Twet
= TSL −wet
(0.94 + 0.38 ABS( M − 0.4) )( )
ρ
1.4 0.8
ρ
Tdry
= 0.9 TSL −dry
(0.907 + 0.262 ABS( M − 0.5) )( )
ρSL
2 ρ 0.8
Twet
= TSL −wet
(0.954 + 0.38 ABS( M − 0.4) )( )
ρ
SL
1.5 0.8
However an installed engine deck for a LBR-TF with an axisymmetric center body inlet and a
mixed flow ejector nozzle was supplied with the RFP. Since it included physical dimensions and
fuel flow values the RFP engine deck was used instead of the above equations. The RFP engine
specifications are shown in Table 6.I.
Table 6.I - Engine Specifications of RFP Supplied Engine
Engine and Nozzle Length
Propulsion System Length
Fan Face Diameter
Maximum Diameter
Weight with Nozzle
SL
310 inches (787 cm)
425 inches (1080 cm)
50 inches (127 cm)
65 inches (165 cm)
7200 pounds (3266 kg)
The engine supplied by the RFP includes fuel flow and thrust data for part power, idle power,
and military power. All engine data supplied by the RFP is corrected to sea level and a Mach
number of zero. Therefore, every value for thrust and fuel flow at each altitude and Mach
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