1. Propulsion Challenges: Past, Present and Future Dr. Alan Garscadden Chief Scientist Propulsion Directorate Air Force Research Laboratory

2. 2 Propulsion Correlations Advances were made by prepared minds James Watt: latent heat concepts from Professor Black Charles Parsons: Astrophysics from father, Earl of Rosse Hans Von Ohain: physics training Gottingen by R. W. Pohl Advances were made by access to other resources and technologies Watt: M. Boulton: manufacturing techniques Parsons: private wealth and large scale engineering Whittle: hindered by lack of either correlation Von Ohain: Heinkel-airframe design & engineering

3. 3 Past Challenges James Watt and Matthew Boultonc1776 Earl of Rosse and Charles Parsonsc1890 US National Bureau of Standards1922 Whittlec1930 Von Ohain and Ernst Heinkel27 August 1939

4. 4 Past Challenges James Watt and Matthew Boulton: seals, machining ----New lathe by Wilkinson Earl of Rosse and Charles Parsons: higher engine speed & scaling----solution led to Dreadnaughts US National Bureau of Standards: rejected jet propulsion because of calculations on efficiency: did not foresee higher speed and higher altitude flight Whittle: limited by funds; by inefficient combustion Von Ohain and Ernst Heinkel; combustion/ blade fatigue

5. 5 HE 178 HeS-3B Turbojet

6. Ernst Heinkel (left) and Hans von Ohain

7. 7 Present Challenges Increased Thermodynamic Propulsion Efficiency +10 to +20% Increased Transmission Propulsion Efficiency Higher Bypass Ratios  10, may need gearbox between power turbine and fan  15, may need UDF: unducted fan Improved Materials Novel Thermal Management

8. 8 Ideal Cycle Fuel Efficiency (@Stoichiometric Limit) Environment Temperature = 3050 o F Environment Temperature = 3800 o F Cooled cooling air Environment Temperature = 2000 o F Significant Performance Growth Potential

9. 9 VAATE Cooled Ceramic High Temp. Ni Disks Intermetallic Blades & Vanes Cooled Cooling Air Liquid/Vapor Cooled +800 o F Advanced Materials, Cooled Cooling Air & Innovative Designs Enable Next Major Turbine Temperature Increase Cooling

10. 10 Future Challenges Air Breathing Access to Space Combined Cycle Hypersonic Flight Long Range Strike Thermal Management Synergistic Fuels Management

11. 11 Cruising Speeds of Insects, Birds, and Airplanes, and the Speed for Minimum Power Consumption -5-4-3-2-10123456 reference Bejan Pheasant

12. 12 Propulsion Options in 3-D Space of ISP, Specific Mass and T/W

13. 13 Air Breathing Access to Space and Combined Cycle Engines Expendable turbine engines to Mach 4 Hydrocarbon fueled scramjet engines to Mach 8 Liquid hydrogen fueled scramjet engines from Mach 8 to Mach 14 Rockets from Mach 14 to Mach 26 Re-entry mode(s)

14. 14 New Propellant Technologies Monopropellants Alternative hydrocarbons Gelled hydrogen Metallized gelled propellants High energy density materials reference NASA / TM-97-206228

15. 15 New Propellant Impacts Significant higher density Boil-off reductions Slosh reduction Higher payloads Increased safety and reduced overheads Improved upper atmosphere performance Need improved thermal management Need improved controls reference NASA / TM-97-206228

16. Hungarian-born Theodore von Karman is considered one of the great aeronautical scientists of the 20th century

17. Hans von Ohain at Wright Patterson Air Force Base

18. X-15 Air-launched, rocket-powered hypersonic research vehicle