Grant nov99
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This document provides an update on an advanced counter-rotating disk wing aircraft concept being developed by Diversitech, Inc. Key points include: - FLOPS analysis was performed to analyze the fixed wing mission capabilities. Results showed a maximum speed of 300 knots and range of 650 nm for a 26ft diameter disk. - Rotor blade sizing was determined to provide vertical lift for take-off and landing, with a 26ft diameter rotor designed using 650shp of available engine power. - Aerodynamic analysis of the disk wing profile was conducted using DATCOM, showing it can provide sufficient lift at take-off speed with 12 degrees angle of attack using a 26ft diameter disk.
Grant nov99
- 1. 1 AN ADVANCED COUNTER-ROTATING DISK WING AIRCRAFT CONCEPT Program Update Presented to NIAC By Carl Grant November 9th , 1999 DIVERSITECH, INC. Phone: (513) 772-4447 Fax: (513) 772-4476 email: [email protected]
- 2. 2 INTRODUCTION • US Patent 4,913,376 “VTLH autogyro” filed by Franklin E. Black, April 3, 1990. Outlined basic “MODUS” concept. - disc wing for fixed wing flight - bladed counter-rotating discs for hover - gimbaled & RPM control • Preliminary sizing for MODUS - XR, a high speed VTOL reconnaissance rotorcraft, performed by Vmax Technologies, for Black Technologies, 1995 - Max Takeoff Weight 3300lb - available engine power is 650 shp for TKOFF, & 450 shp for CRZ. - Max SL speed 232 knots, Max @ 20K ft 150 knots - Max range, disk only, 648 nm. • M85, NASA AMES design, max speed M 0.85, MGTW 10,200lb, ~400nm, 1991. • Diversitech, Inc., NIAC contract, “An Advanced Counter-Rotating Disk Wing Aircraft Concept”, NIAC/USR Grant No. 07600-028, June 1st, 1999. - Max Takeoff Weight 3300lb - available engine power is 650 shp for TKOFF, & 450 shp for CRZ. - Max SL speed 300 knots, Max @ 24K ft 230 knots - Max range, disk only, 650 nm.
- 3. 3 Advanced High Speed Rotorcraft (AHSR) Study Objectives • From preliminary MODUS geometric layout define basic AHSR mission • Perform a Fixed wing mission analysis using NASA Langley FLOPS program • Determine Required Disk Size • Determine Rotor Blade Sizing for vertical lift • Perform a Hover Analysis • Perform an Aeromechanical Analysis • Generate Preliminary model drawings.
- 4. 4 From preliminary geometric layout define basic mission ( Basic Dimensions) • Disk Diameter 16ft • Rotor Diameter 26ft • Disk Area 201ft2 • Empennage Area 15ft2 • Cathedral 45o • Taper 0.28 • Thickness 12% • Frontal Area 20.54ft2 • Height 10.6ft • Length 29.4ft • Max Rotation 13o • Propeller Diameter 80ins • Engine (Allison250-C30) 650-450 shp • MGTOW 3300lbs
- 5. 5 From preliminary geometric layout define basic mission ( Estimated Weight Breakdown) • Structure - Fuselage 240 lbs. - Empenage 40 lbs. - Main Gear 120 lbs. - Nose Gear 30 lbs. - Disk 150 lbs. - Rotor Blades (x4) 120 lbs. TOTAL 700 lbs. • Propulsion System - Engine 280 lbs. - Shafts 60 lbs. - Clutch/G-box 100 lbs. - Propeller 60 lbs. - Actuators 50 lbs. TOTAL 750 lbs. • Systems - Electrical 190 lbs. - Battery 40 lbs. - Seats(2) 80 lbs. - Avionics 340 lbs. - FLIR 60 lbs. - Flight Inst. 40 lbs. TOTAL 750 lbs. TOTAL EMPTY WEIGHT2200 lbs. • Crew - Pilot 200 lbs. - Observer 200 lbs. • Fuel - Internal 700 lbs. • Payload 1100 lbs. MAXIMUM TAKEOFF GROSS 3300 lbs.
- 6. 6 Perform a Fixed wing mission analysis using NASA Langley FLOPS program • The FLOPS program is a NASA Langley Flight Optimization System. • Diversitech used FLOPS release 5.94, revised 17 July 1998, to perform the fixed-wing analysis. • The goal of the FLOPS analysis was to verify the ability of the Vmax MODUS design to fly a set mission. • The polars used for input to the FLOPS program were generated from the MODUS-XR design. • Assumes a non-oxygen vehicle, i.e. not pressurized with max altitude of 12,500ft • The pusher, turbo prop design, cycle was generated from a Hartzell 80”, 5 blade, propeller design, and was generated using the NASA Navy Engine Program, (NNEP). • For the FLOPS analysis it was assumed that there would be available 650 shp for Take off and 450 shp for cruise. Required power determined from required speed. • The Clark-Y airfoil profile was assumed for the disk. • Varying Disk diameters, 22’, 26’ & 30’, considered.
- 7. 7 The AHS Rotorcraft Nominal Mission Used with FLOPS • Max power takeoff • Climb to cruise altitude of 12,500ft • 1½ hrs OUT • descend to loiter altitude 50ft, approx. • Hold on station for 1hr • Climb back to cruise altitude 12,500ft • 1½ hrs BACK
- 8. 8 FLOPS Analysis Results (Range) Flight Envelope 25000 20000 15000 10000 5000 0 0 50 100 150 200 250 300 350 Velocity (knots) Altitude (ft) 300ft/min Climb Rate Stall Speed CL~1.2 Shaft HP Limited This Data includes a 1hr hold on station n=1 ( I.e. 1g loading) • 1g loading assumed • Stall speed 61 knots CL=1.16, 0ft to 900ft • At 900ft & 70 knots to max altitude 23800ft at 227 knots, climb rate 300ft/min • At altitude 11500ft and 311 knots to SL, Shaft HP limited
- 9. 9 FLOPS Analysis Results ( Endurance ) Endurance 5.0 4.8 4.6 4.4 4.2 4.0 3.8 3.6 3.4 3.2 3.0 20 22 24 26 28 30 32 Rotor/Disk Diameter (ft) Endurance (hrs) constant fuel wt Increased fuel wt Optimum Mo for endurance ~ 0.325 includes : 1 1/2 hr out 1 1/2 hrs back with 1 hr hold. Total time 4hrs All calcs performed at 12500ft Assumes contant fuel wt of 700lb Off-load fuel dto maintain cont GTOW as disk size increases • assumes 1½ hrs OUT + 1hr HOLD + 1½ hrs BACK • Assumes constant fuel weight (dotted line) • Assumes reduced fuel weight due to increased disk weight with GTOW constant ( solid line) • All data shown is for 12,500 ft
- 10. 10 FLOPS Analysis Results ( Range Optimum/Max Cruise) Range Optimum/Max Cruise (disk only- b lades retracted) 750 700 650 600 550 500 450 400 350 300 250 Assumes constant fuel wt of 700lb 20 22 24 26 28 30 32 Rotor/Disk D iameter (ft) Range (nm) • Assumes Disk only, blades retracted • Assumes a constant 0.625 blade to disk ratio • Assumes 12500ft limited max CRZ altitude • Upper curves are for constant fuel weights of 700lbs • Lower curves are for constant GTOW, i.e. when disk size increases, fuel weight decreases to maintain GTOW of 3300lbs Opt Mo C ont Fuel W t Opt M o Redu fuel W t Max M o Redu Fuel Max M o Const Fuel Optimum cruise Mo specific Max cruise Mo This data includes 1/2 h r ho ld Assumes a constant 0.625 blade to d isk diam eter Assumes 12500ft limited m ax a ltitude Range decreases on these lines due to constant GTOW . Therefore as d isk s ize increases, fuel weight decreases.
- 11. 11 FLOPS Analysis Results continued (Range - 26ft Diameter Rotor) Range - 26 ft system 700 650 600 550 500 450 400 350 300 250 0.00 0.10 0.20 0.30 0.40 0.50 0.60 Mo Range - nm 12500 ft 8000 ft 5000 ft 2000 ft 12,500 ft 8,000 ft 5,000 ft 2,000 ft • Curves shown are for varying altitudes, with the upper limit being 12500ft. • Assumes 16ft diameter disk with 5ft long blades • Data shown is for “fixed wing” operation with blades retracted • This data indicates the range decrease due to altitude
- 12. 12 FLOPS Analysis Results continued ( Range - 12,500ft max altitude, varying disk diameters) Range ( 12,500ft Varying Disk Diameters) 700 650 600 550 500 450 400 350 300 250 0.00 0.10 0.20 0.30 0.40 0.50 0.60 Mo Range (nm) • Data shows variation in range based on changes in disk diameter. • Assumes constant GTOW • As disk diameter increases, fuel weight decreased to maintain 3300 lbs. GTOW • A curve for a 30ft diameter disk, with constant fuel weight of 700 lbs., is also shown • Note: at 12,500ft M0.5 is approximately 300 knots 22ft Disk 26ft Disk 30ft Disk 30ft Disk (Inc TOGW) 22ft Disk 26ft Disk 30ft Disk incr TOGW 30ft Disk
- 13. 13 Determine Required Disk Size • The disk size chosen for the 3300 lbs.. GTOW vehicle is 26ft • This is based on a 16ft diameter disk with 5ft rotor blades • The preliminary airfoil shape chosen for the disk is a NACA 661-012 ( chosen to provide sufficient internal volume for mechanisms) • For symmetry the LE to 50% chord is used for disk profile • Size chosen based on an FAA stall speed requirement, for light aircraft, of 61 knots • Because of the potential for tail, or propeller, drag the landing AOA is <15o • Assume the landing weight is 2950 lbs.. ( i.e. 3300lbs. minus half the fuel wt) • At 61 knot stall speed data obtained from the FLOPS analysis indicates that the Clark-Y airfoil has a required CL≤1.16, which is achievable with a 12o AOA. NACA 66-012 15 10 5 0 -5 -10 -15 0 50 100 150 200 250 chord thickness y-upper y-low er Pseudo LE/LE Rotor Disc Profile 15 10 5 0 -5 -10 -15 0 50 100 150 200 250 chord thickness y-upper y-low er
- 14. 14 Perform Wing Lift Characteristic Analysis using US Airforce Digital DATCOM Alt = 12500 ft Pusher Propeller @RPM = 2100 2500 2000 1500 1000 500 0 Drag vs Speed Thrust vs Speed 0 50 100 150 200 250 300 350 400 450 500 Speed - kts Thrust or Drag - lb Weight 3500 650 450 • Analysis performed to determine the Lift Characteristics of the pseudo NACA 661-012 airfoil • Used NACA 661-012 pseudo airfoil profile, with a circular planform approximated with a polygon. • Neglected gap between counter-rotating disks • At 12,500ft, if 650 shp is available, the max speed is < 240 knots ( determined by thrust vs drag) • At 12,500ft, if 450 shp is available, the max speed is < 175 knots • Need to determine correct polars for this airfoil and perform new FLOPS analysis
- 15. Perform Wing Lift Characteristic Analysis using US Airforce Digital DATCOM 15 Alt = 20000 ft RPM = 2100 2500 2000 1500 1000 500 0 0 50 100 150 200 250 300 350 400 450 500 Speed - k ts Thrust or Drag - lb W eight 3500 650 450 Thrust vs S peed Drag vs Speed • At 20,000ft, if 650 shp is available, the max speed is < 250 knots ( determined by thrust vs drag) • At 20,000ft, if 450 shp is available, insufficient thrust is being generated by the pusher propeller to overcome the drag. Therefore, a higher horsepower would be required to overcome the drag at this altitude.
- 16. 16 Determine Rotor Blade Sizing for vertical lift • Rotor blade size determined for a 26ft diameter rotor, with a 16ft hub, based on the required GTOW of 3300lbs. • Hartzell Propeller Company, Piqua, OH, performed the design, and provided the propeller map. • Design based on 4 rotor blades with a tip diameter of 26ft. • Hub diameter of 16ft included in design • Available power=650 shp • Design tip mach number of 0.9 used. • Blade design has 60” length, and 7” chord.
- 17. 17 Determine Rotor Blade Sizing for vertical lift Radius width thick twist Cl des NACA Airfoil(chosen by Diversitech) 95 7.0 1.5 32.0 .50 16-5-21 105 7.0 1.0 30 .70 16-7-14.3 115 7.0 .70 28.5 .65 65-6.5-10 125 7.0 .55 27.5 .53 65-6.5-10 135 7.0 .40 26.7 .41 65-6.5-10 145 7.0 .30 25.8 .30 65-3-04 150 6.0 .24 25.3 .25 65-3-04 156 4.0 .20 24.9 .20 64-2-04
- 18. 18 Perform a Hover Analysis J = V/nD = 0.05 5500 5000 4500 4000 3500 3000 2500 2000 1500 hp = 650 hp = 450 650 hp 450 hp 200 300 400 500 600 700 800 900 1000 RPM Thrust - lb • With available 650 shp from the Allison 250-C30 engine, and the provided Hartzell rotor design, is it possible to lift 3300 lbs.. vertically? • To provide a margin of error 3500 lbs.. lift is assumed to be required • Analysis performed @SL with NO ground/fountain effect, • Data shows that with 650 shp available, approx. 5000lbs of lift can be generated • Data shows that with 450 shp available, approx. 4000lbs of lift can be generated • The 450 shp condition allows remaining hp to be used for up&away forward flight
- 19. 19 Pseudo Transition Analysis • As the rotorcraft transitions to forward flight it is assumed that the amount of lift being generated by the rotor blades will decrease. • In order to transition, a constant forward velocity is chosen such that there is sufficient horsepower to (1) drive the vehicle forward at the chosen velocity (2) provide sufficient horsepower to rotor in order to generate 3500 lbs. of vertical lift • Analysis assumes 0o AOA for the disk • Analysis does not account for blades extended drag • An altitude of 2000ft is chosen, and assumed to be reasonable
- 20. 20 Pseudo Transition Analysis continued Pseudo at speed Rotor lift Alt = 2000 ft 1000 900 800 700 600 500 400 300 200 100 0 0 100 200 300 400 500 600 700 800 900 RPM Power - hp Fwd Vel Knots 0 Fwd Vel Knots 50 Fwd Vel Knots 100 Fwd Vel Knots 150 Fwd Vel Knots 200 3500 lbs Disc Lift and Propeller Thrust Alt = 2000 ft RPM = 2000 2500 2000 1500 1000 500 0 @650 shp Thrust vs 0 50 100 150 200 250 300 350 400 450 500 Speed - kts Thrust or Drag - lb • For 0lbs lift on disk, 200 shp is required to maintain a 150 knot forward speed • At 150 knots a pseudo rotor lift of 3500 lbs. requires 400 shp • There is sufficient engine power, 650 shp, to maintain this condition at 2000 ft altitude. • At 150 knots, in order to generate 3500 lbs.of lift from the disk, an AOA will need to be set, and a minimum 400 shp is required. • Transition is postulated to occur by transferring power from the rotor to the propeller, whilst simultaneously changing AOA on the disc. • The increased disk lift will need to compensate for the reduced rotor lift due to the decreasing rotor power. Weight 3500 Weight 0 800 650 400 200 3500 lbs of disk lift D d 0 lbs of disk lift Drag vs speed @800 shp Thrust vs d @400 shp Thrust vs d d @200 shp Thrust vs d
- 21. 21 Perform an Aeromechanical Analysis • Preliminary Aeromechanical analysis performed by Georgia Institute of Technology, using the multi-body dynamics tool DYMORE. • Assumes 4 bladed rotor, with the Hartzell blade design attached to the 16ft diameter NACA 661-012 disk. • The analysis assumes a rigid disk boundary condition • Work Currently in progress
- 22. 22 Generate Preliminary model drawings. • Once the aeromechanical analysis is completed, assuming there are no changes required to the design, work will begin on the preliminary drawing layout of the AHSR rotor system, as determined by the results of this study.
- 23. 23 CONCLUSIONS • A preliminary vehicle sizing for a 3300 lbs. GTOW Advanced High Speed Rotorcraft is nearing completion. • The feasibility of a 3300 lbs GTOW vehicle with a 650 nm range and max speed of approx. 300 knots has been demonstrated. • Results indicate that increased engine power may be required to meet certain mission goals such as transition. (Suggested engine is the P&W PT6A-42 engine; 850 shp, 403 lbs. weight). • A refined FLOPS analysis that includes the NACA 661-012 airfoil is also suggested. • PHASE II follow on program will encompass a CFD analysis of the disk airfoil, a refined FLOPS analysis (to include transition), along with a more detailed mechanical and aeromechanical analysis. • For mechanical and weight purposes a single disk, with tail blowing torque control, will be studied. • Outstanding work remaining to be completed (1) complete aeromechanical analysis (2) generate preliminary drawings (3) write final report