1. AAE 450 Spring 2008 William Yeong Liang Ling 1/17/2008 Propulsion A Feasibility Analysis on the Use of Air Launch Vehicles Credit to Nicole Wilcox for obtaining military fuel prices and Jerald Balta and Stephanie Morris for research help Propulsion

2. AAE 450 Spring 2008 Comparison of air launch methods Propulsion Aircraft launch (h = 15,250m, α = 30°, v = 340m/s) Balloon launch (h = 15,250m, α = 30°, v = 0m/s) Total Δv benefit~1,000 m/s~500 m/s Ease of implementation Proven separation mode for “captive on bottom” Both commercial (White Knight) and military (F-15) aircraft can be utilized with almost no modifications Balloons unlikely to be designed to sustain the environment of launch (once off vehicle) Estimated carrier costs per launch ~$45,000 Avgas loaded to full capacity of F-15 ($3/L) Maintenance costs $? ~$1,155,000 for 231,000L of He required to lift 231kg ($5/L commercial) ~$11,550 ($0.05/L military) Production cost per balloon if non-reusable $?

3. AAE 450 Spring 2008 Future Work  A detailed analysis of the Δv benefits at variable altitudes, flight velocities and angle of release  Comparison between the running costs of a military jet and the procurement costs of a commercial carrier vehicle  Estimate of the developmental cost of a non- reusable balloon Propulsion

4. AAE 450 Spring 2008 References  Sarigul-Klijn, N., et al. "Air Launching Earth-to-Orbit Vehicles: Delta V gains from Launch Conditions and Vehicle Aerodynamics," AIAA Paper 2004-872, Jan 2004.  Sarigul-Klijn, N., et al. "A Study of Air Launch Methods for RLVs,” AIAA Paper 2001-4619, August 2001.  Gizinski, J., et al. “Small Satellite Delivery Using a Balloon-Based Launch System,” AIAA Paper 92-1845, March 1992.  Defense Energy Support Center, “MISSILE FUELS STANDARD PRICES EFFECTIVE 1 OCT 2007,” Aerospace Energy Reference, November 2007 Propulsion

5. AAE 450 Spring 2008 Diameter of a spherical balloon  Lifting capacity of helium is ~1g/L at sea level  Taking a lifting requirement of 231kg (as taken from the weight of the air-to-air AIM-7 Sparrow)  231,000L (231m³) required to lift 231kg  Assuming a spherical balloon (V = 4/3 πr³)  r = 3.8m (d = 7.6m) Propulsion

6. AAE 450 Spring 2008 Cost of helium  231,000L required  At a commercial cost of $5/L, this amounts to $1,155,000  At a military cost of $0.05/L, this amounts to $11,550 Propulsion

7. AAE 450 Spring 2008 Cost of jet fuel  Taking the F-15 F100-PW-229 engine as a base model  Military thrust = 79.1kN  Specific fuel consumption = 77.5kg/kNh  Fuel consumption = 77.5 x 79.1 = 6130.25kg/h = 1.7kg/s Propulsion

8. AAE 450 Spring 2008 Cost of jet fuel  Military price of Avgas (FY2008) = $3.00/L  Density of Avgas at 15°C = 0.72kg/L  Price = $4.17/kg  Side note: Cost of running at military thrust = $7.08/s  Maximum fuel capacity of the F-15A = 10655kg  Cost to fill to maximum capacity = $44431.35 Propulsion

9. AAE 450 Spring 2008 Δv benefits (v = 0m/s) Sarigul-Klijn, N., et al. "Air Launching Earth-to-Orbit Vehicles: Delta V gains from Launch Conditions and Vehicle Aerodynamics," AIAA Paper 2004-872, Jan 2004. p9, Fig 5 Propulsion

10. AAE 450 Spring 2008 Δv benefits (v = 340m/s) Sarigul-Klijn, N., et al. "Air Launching Earth-to-Orbit Vehicles: Delta V gains from Launch Conditions and Vehicle Aerodynamics," AIAA Paper 2004-872, Jan 2004. p9, Fig 5 Propulsion