Aircraft Design for Expeditionary Warfare Introduction Mission Introduction

Aircraft Design for Expeditionary Warfare Introduction & Mission

Introduction Aircraft design study has been going since 7/02. l Initially four concepts were singled out to meet mission requirements. These were: (a) Compound Helicopter (b) Quad-Tiltrotor (c) Reverse Velocity Rotor (RVR) Compound Helicopter (d) Joint Heavy Lift (JHL) Aircraft (Based on JSF lift fan technology. ) l These concepts have now been narrowed down to the RVR Compound Helicopter and JHL Aircraft. l 2

Mission Requirements l Key requirements: – – 300 nm radius of action 37, 500 lb payload 200– 250 kt cruising speed Capable of carrying vehicles like LAV, MTVR, or HEMAT (internal or external) – Capable of 15 minute cargo on-load or off-load using only aircrew – Shipboard compatible 3

Mission Profile 4

CH-83 Condor A Design Solution for Expeditionary Warfare Vertical Heavy Lift

Team Members l ENS Ben Carter, USN Structures/Wing l ENS John Ciaravino, USN Rotors l MAJ Choon Lim, RSAF Flight Mechanics/Auxiliary Thrust l ENS Jason Papadopoulos, USN Engineering Drawings/Cargo Configuration l ENS Matt Rodgers, USN Hover Performance/Dynamics l CPT Michael Tan, RSAF Sizing/Flight Mechanics l MAJ Steven Van Riper, USA Team Leader 6

Outline l l l l Overcoming Current Rotary Wing Limitations Basic Attributes Sizing Calculations General Configurations and Dimensions RVR Concept Rotor Selection and Performance Airframe Structures and Compound Wing Engine Selection Hover Performance Auxiliary Propulsion Compound Wing Selection Cruise Flight Performance Cargo Capability Conclusion Questions 7

Overcoming Current Limitations l l l Current rotary wing aircraft are limited to cruise airspeeds of 150 -160 knots. Retreating blade stall and high tip speeds, in excess of Mach 1, set speed limitations. Compound helicopters successfully increase the speed range to 200 -220 knots using wings and auxiliary propulsion but pay a penalty in terms of rotor drag and performance The emerging RVR initiative allows for performance increases without sacrificing desirable rotor traits. Coupling the RVR with a compound wing provides the performance balance required to satisfy Heavy Lift Requirements. 8

Basic Attributes l l l l Eight bladed main rotor with RVR technology Conventional anti-torque system 2 fuselage mounted turboshaft engines 2 wing mounted turboprop engines Fuselage-mounted high wing Fuselage capacity equivalent to C-130 J Aft loading ramp 9

Sizing Calculations l Calculation – Equations from Prouty • RVR Design Spreadsheet with optimization module • Disk loading, wing area, hover performance, etc. l Comparison – Our design to Sikorsky’s RVR Compound, the CH-53 E and the MI-26 – Our figures to JANRAD figures for hover performance l Selection – Based on the design resulting in the best payload, range, and speed 10

Sizing Calculations Vehicle: Mission Parameters: Cruise Speed: 215 kts Range: 600 nm Payload: 37, 500 lbs Significant considerations: Gross Weight : 117, 300 lbs Payload : 37, 500 lbs Empty Weight : 64, 500 lbs Fuel Capacity : 15, 300 lbs HP Required : 22, 700 HP Rotor: (Approx MI 26 sized blades) · 0. 3 hrs of hover + 0. 4 hrs of contingency cruise Radius = 55. 3 ft # Blades: 8 · Power required took into account of typical hot day operation at altitude 4000 PA Blade Chord = 4. 1 ft · 50% of hover RPM in fwd flt (RVR) · High advance ratio (0. 9) (RVR) Solidity = 0. 19 Ω = 105 RPM (Hover) Disk Loading = 12. 2 lb/ft 2 (< V-22 & CH-53 E) Compound wing: Wing Span: 96 ft Wing Area: 1249 ft 2 Main engines: 4 x 6, 000 HP (AE 1107 C, V-22 engine) 11

Sizing Calculations Significant weight breakdown: Rotor system (include tail): 12, 000 lbs Fuselage : 15, 000 lbs Propulsion system : 12, 500 lbs Drive system : 11, 500 lbs Furnishing & equipment : 6, 400 lbs Total empty weight: · Estimated to be 64, 500 lbs Clean aircraft CG location: · Estimated to be at FS 55 · => 55 ft from nose · => 62% of wing MAC · => 2 ft aft of main transmission 12

General Configuration **Spot Factor : Approximately 1. 4 x CH-53 E 13

Dimensions Rotor Diameter: 109 ft Wing Span: 96 ft Wing Chord : 17. 75 ft @ root 8. 5 ft @ tip Blade Chord : 4 ft 14

Dimensions Overall Length : 120 ft Overall Height : 46. 4 ft 15

RVR Concept l Reverse velocity rotor – A rotor system that uses double-ended airfoils as rotor blades, variable speed transmission, 1 -P plus 2 -P control and auxiliary propulsion. Typical RVR airfoil Reverse flow region Lift generation regardless of flow direction 16

RVR Concept l RVR wind tunnel testing 4 -bladed small scale RVR model Ref: Further Model Wind Tunnel Tests of a Reverse Velocity Rotor System; Ewans, J. R. , Mc. Hugh, F. J. , Seagrist, R. P. , Taylor, R. B. , July, 1975. 17

Rotor Parameters l l l 1 -1 Planform, Articulated Blades 8 Bladed Rotor 55. 3 ft Radius 4. 1 ft Chord Max Tip Mach Number: 0. 75 20% of lift in forward flight generated by rotor 18

Airframe Structures l Primary design consideration: – Reducing weight through extensive use of composite materials, particularly in primary structures like the wing and fuselage. – Planning to use at least 70% composites in the structure, with a goal of reducing empty weight by approximately 10%. – Researching thermoplastics for possible use in structural design. Component Failure Areas Tentative Material Layer Orientation Fuselage Compression Graphite/Epoxy 25% 0°, 50% +/-45°, 25% 90° Fuselage (sides) Shear, Torsion Wing (upper) Buckling Graphite/Epoxy 35% 0°, 30% +/-45°, 35% 90° Wing (lower) Fatigue Control Surfaces Tension Graphite/Epoxy 50% 0°, 50% 90° Shafts Bending, Torsion Graphite/Epoxy 100% +/-45° 19

Compound Wing Selection l Primary design consideration: – Providing 80% lift at a cruise condition of 205 kts and 8000 ft. (Approximately 94, 000 lbs. ) – Ailerons to be incorporated for roll control in cruise. l Parameter Value Span 96 ft Mean Chord 13 ft Area 1250 ft 2 Aspect Ratio 7. 38 Taper Ratio 0. 48 Composite construction: – Filament layer orientation chosen to maximize performance in both tension and compression. 20

Airfoil Selection l Airfoil – Chosen for good lift at low angles of attack, and low drag at our mission’s cruise CL. Parameter Value Airfoil NACA 632 -615 Lift Curve Slope 5. 73 rad-1 Design Cruise CL 0. 7 Angle of Incidence 2 deg CL=0. 7 21

Engine Selection l Design requirement l Concept l Engine Description l Power available 22

Engine Selection The propulsion system should be able to provide adequate power for the CH-83 Condor to perform a vertical takeoff with payload weight of 37, 000 lbs at a vertical rate of climb of 200 ft/ min in a 4000 ft, 95 F operating environment. l It has adequate power to enable Condor to cruise at 8, 000 ft altitude (10, 000 ft max ceiling) with speed above 200 knots. l 23

Engine Selection Main Gearbox Clutch Turboprop engine Hover Flight • Clutch engaged • 4 engines drive main rotor Turboshaft engine Tail Transmission Forward Flight • Clutch disengaged • Forward propulsion by 2 x turboprop engines • Turboshaft engines drive main rotor at 50% nominal speed 24

Engine Selection AE 1107 C – Turboshaft AE 2100 D 3 – Turboprop • Powered V-22 Osprey • Max Power (SL, ISA): 6, 150 shp • Weight : 971 lbs • SFC : 0. 41 lbs/hr-shp • Powered C-130 J • Max Power (SL, ISA): 6, 000 shp • Weight : 1, 500 lbs • SFC : 0. 41 lbs/hr-shp Both powerplants share common core components. 25

Engine Selection Power available chart With 4 engines Power available (SL, ISA) = 25, 200 Shp Power available (4, 000 ft, 95 F) = 22, 796 Shp 26

Hover Performance l Team Design Spread Sheet Power Required Rotor Torque CT/sigma CQ/sigma Solidity 17, 340 hp 864, 873 ft-lb. 090. 012. 190 l JANRAD Calculations Power Required Rotor Torque CT/sigma CQ/sigma Solidity 15, 290 hp 764, 465 ft-lb. 097. 011. 189 JANRAD (Joint Army Navy Rotor Analysis and Design) NPS Matlab based program used for rotor-craft analysis JANRAD calculations show more optimistic numbers than the team design spreadsheet 27

Hover Performance Anti-torque Tail Rotor Design (Using Team Design Spreadsheet Numbers) Required Anti-Torque 864, 873 ft-lb Tail Moment Arm 68 ft Required Side Force 15, 555 lb Tail Rotor Parameters Power Calculation Fan Diameter 25 ft CT/sigma . 13 Fan Rotational Speed 10 rev/s CQ/sigma . 03 Fan Tip Mach Number . 70 Torque 38892 ft-lb Solidity . 20 Number of blades 6 Chord 1. 31 ft Power Required 4443 hp 28

Auxiliary Propulsion Thrust Calculations density 0. 00197 slug/ ft^3 Velocity 363. 4 ft/s Parasite Drag 10330 lb Induced Drag 2801 lb Reqd Thrust (per prop) 6566 lb Prop Efficiency 0. 9 Shaft Power 9639 hp Shaft Power (per prop) 4820 hp Number of blades 6 Prop Diameter (Roskam II pg 128) 15. 0 ft Prop Rotational Speed 19. 0 rev/s Prop Tip Mach Number 0. 78 Advance Ratio 1. 36 29

Cruise Flight Performance Significant considerations: · Calculation took into account of typical hot day operation at altitude 4000 PA · Wing CL of. 7 · Tip path plane angle 1 o · Rotor coning angle 1. 44 o Drag forces: Fuselage : 9, 200 lbs Rotor drag : 3, 000 lbs Wing drag : 4, 000 lbs Hort tail drag : 450 lbs Vert tail drag : 220 lbs Lift forces: Compound wing : 86, 000 lbs (73%) Rotor system 31, 300 lbs (27%) : 30

Cruise Flight Performance 31

Cruise Flight Performance 32

Cargo Seven Load Cases tested 1. 2. 3. 4. 5. 6. 7. Troop Transport Air Ambulance Standard Pallets MTVR HEMAT LAV M 998 HMMWV (Humvee) Cargo Box 33

Cargo 1. Troop Transport • 124 Category Two Passengers 2. Air Ambulance • 63 Stokes Litters 3. Standard Pallets • 3 pallets full loaded, 6 distributed 4. MTVR • 1 + loaded pallet 5. HEMAT • 1 + loaded pallet 6. LAV • 1 + loaded pallet 7. Humvee • 3 or less depending on pallet requirements IN EACH LOAD CASE THE CENTER OF GRAVITY OF THE ENTIRE AIRCRAFT REMAINED IN FRONT OF THE NEUTRAL POINT AND PROVIDED A SATISFACTORY STATIC MARGIN. 34

Conclusions The CH-83 design is viable and can meet Expeditionary Warfare Heavy Lift requirements. l 300 nm radius of action 37, 500 lb payload 200– 250 kts cruising speed Capable of carrying vehicles like LAV, MTVR, or HEMAT (internal or external) Capable of 15 minute cargo on-load or off-load using only aircrew Shipboard compatible Design is based on proven compound helicopter technology. l Main concern is the application of RVR technology at high cruise speeds and gross weights l 35

Questions? 36