Regenerative Electric-powered Flight J. Philip Barnes 1 Regenerative Electric Flight Synergy and Integration of Dual-role Machines J. Philip Barnes 27.

Regenerative Electric-powered Flight J. Philip Barnes 1 Regenerative Electric Flight Synergy and Integration of Dual-role Machines J. Philip Barnes 27 Dec 2014 Animated slides: F5 key Also: View ~ "Notes Page"

Regenerative Electric-powered Flight J. Philip Barnes 2 Great theoreticians and experimentalists (all Ph.D.) Ludwig Prandtl - Germany Hermann Glauert - U.K. Royal Aeronautical Society Albert Betz - Germany Paul MacCready - USA

3 Presentation Contents Regen. elec. flight: Origin & Introduction Dual-role machines: – Propeller and wind turbine – DC motor-generator – Brushless motor-generator Integration: – Inverter-rectifier – DC boost converter – "Chop" Vs. "Boost" architecture “Regenosoar” aircraft concept Summary & Look Ahead Regen. elec. flight: Origin & Introduction Dual-role machines: – Propeller and wind turbine – DC motor-generator – Brushless motor-generator Integration: – Inverter-rectifier – DC boost converter – "Chop" Vs. "Boost" architecture “Regenosoar” aircraft concept Summary & Look Ahead

4 Exploit opportunities to store Vs. expend energy Exploit opportunities to store Vs. expend energy Energy Storage Unit : Battery and/or: Ultra capacitor Flywheel w/M-G Energy Storage Unit : Battery and/or: Ultra capacitor Flywheel w/M-G Regen Aircraft Elements and Operation Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com Power Electronics Power Electronics Motor-Gen (M-G) Motor-Gen (M-G) Windprop Fixed rotation direction Sign change with mode Thrust, Torque Power, Current

Blade angle (   ) at radius (r) is measured from rotation plane to the chord line at (r) Propeller Wake, Pitch, and Blade Angles Effect of more blades (fixed T, R): Steep blade angle, much lower RPM Lower tip Mach, much-reduced noise High torque → dual & counter rotation Numerically integrate wake for loading Effect of more blades (fixed T, R): Steep blade angle, much lower RPM Lower tip Mach, much-reduced noise High torque → dual & counter rotation Numerically integrate wake for loading Wake induces downwash (normal to local section) Pitch: helix length per rotation h tip = 2  R tan  tip Uniform pitch: r tan  = R tan  tip Blade tip angle (  tip ): 14 o ~ low pitch 30 o ~ high pitch 6 Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

Regenerative Electric-powered Flight J. Philip Barnes 7 Wake and blade induced velocities vs. distance from rotor Wake-induced Blade-induced No swirl upstream No swirl upstream Immediate final swirl Induced axial velocity in the ultimate wake is twice the induced velocity at the rotor Induced axial velocity in the ultimate wake is twice the induced velocity at the rotor Rotor  Wake Blade Wake Blade Slipstream Airflow is symmetric upstream of a pusher Airflow is symmetric upstream of a pusher

Regenerative Electric-powered Flight J. Philip Barnes 8 Test data validating Glauert's rationale on induced velocity Gradual buildup F.E. Weick, Aircraft Propeller Design, McGraw-Hill, p. 102-103 Immediate swirl, as predicted by Glauert

J. Philip Barnes www.HowFliesTheAlbatross.com Propeller or wind turbine Angle of attack = 0 No change to flow direction No change to relative wind Helical drag wake (unloaded)  r tan  = V o (all sections) or, r tan  = const.= R tan  tip Propeller or wind turbine Angle of attack = 0 No change to flow direction No change to relative wind Helical drag wake (unloaded)  r tan  = V o (all sections) or, r tan  = const.= R tan  tip Blade section Looking outboard, Blade at 3 o’clock Chord line  Rotor blade velocity diagram - "Pinwheeling" condition Pinwheeling sets up "Betz Condition" Propeller or turbine at no load Perturb  or V o to load rotor Helical wake (drag and/or vortex) Sets blade angle distribution  (r):  = tan -1 [ V o / (  r) ] Says nothing about blade planform Axial wind VoVo VoVo Rotational wind,  r Relative wind W 1  V o W2W2 Helical wake  r

J. Philip Barnes www.HowFliesTheAlbatross.com Non-rotational (axial) inflow Axial velocity locally conserved Final swirl imparted suddenly Helical wake anchored at c/4 Wake ~ aligned with chordline Wake-induced velocity (V i ) Glauert: 2V i  at "rotor out" Absolute velocity (V) increased Relative wind (W) decreased Immediate static pressure rise Propeller blade - comprehensive velocity diagram Glauert: consistent physics & geometry Vortex wake ~ aligned with chord line Betz cond. (wake helix), prop or turbine, with or without rotor loading, provided: r tan  = const. and  =0 (sym. sections) Relative wind W 1  W   r - V i   V 1  Zero-lift line Rotational wind Axial wind V 1  V o +V ix Helical wake vortex sheet W2W2 V 1  r - 2V i  V 2 Blade section Looking outboard Blade at 3 o’clock Chord line  V i  V ix V i

11 Windprop Blade Angle and Operational Mode v  r  w Pinwheel Pinwheeling: Zero angle of attack, root-to-tip - No thrust, no torque, small drag v  r L  w Propeller Efficient prop: Rotate ~115% of “pinwheel RPM,” or fly at 87% of “pinwheel airspeed” v  r -L  w Turbine Efficient turbine: Rotate ~ 87% of “pinwheel RPM,” or fly at 115% of “pinwheel airspeed” Define: “Speed ratio,”   v / v pinwheel = v / [  R tan  tip ] Symmetrical sections and r tan  = R tan  tip Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

12 Speed Ratio,  ≡ v / (  R tan  tip ) 0.50.60.70.80.91.01.11.21.31.41.51.61.71.8 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Force Coefficient, F ≡ f/(q  R 2 ) B=2 2 B=8 8 F Low-RPM 8 Blades,  tip = 30 o High-RPM 2 Blades,  tip = 14 o Speed Ratio,  ≡ v / (  R tan  tip ) 0.50.60.70.80.91.01.11.21.31.41.51.61.71.8 Efficiency 0.0 0.2 0.4 0.6 0.8 1.0  Turbine  / (f v) Blades_  tip 2_14 o 8_30 o c l_min c l_max Propeller f v / (  ) Pinwheel F= -0.011 @ B=2 F= -0.008 @ B=8 Propeller ~ climb Max efficiency Regeneration Max capacity Regeneration Propeller ~ cruise Windprop Efficiency and Thrust r / R 0.000.250.500.751.00 Blade Geometry 0.00 0.05 0.10 0.15 0.20 0.25 0.30 Thickness Chord, c/ R Sym. Sections r tan  = R  tip hub Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com Comparable efficiency by mode Eight blades quieter than two Climb power ~ 7x cruise power Comparable efficiency by mode Eight blades quieter than two Climb power ~ 7x cruise power

   E N turns Generating i vivi vv FpFp FF B i Change to generator mode: Same direction, rotation,  Same sign for EMF,  Sign change of torque,  Sign change of current, i Change to generator mode: Same direction, rotation,  Same sign for EMF,  Sign change of torque,  Sign change of current, i Electromotive force,  = potential energy / charge = work / charge, (F p / q) L = 2 N  (D/2) B L  = NDBL  ≡ k  Electromotive force,  = potential energy / charge = work / charge, (F p / q) L = 2 N  (D/2) B L  = NDBL  ≡ k  Torque,  = 2N (D/2) B (dx/dt) dq = 2N (D/2) B (dq/dt) dx  = NDBiL = NDBL i = k i Torque,  = 2N (D/2) B (dx/dt) dq = 2N (D/2) B (dq/dt) dx  = NDBiL = NDBL i = k i (+) Charge (q) with velocity, V in magnetic field of strength, B: Force vector, F = q V x B (+) Charge (q) with velocity, V in magnetic field of strength, B: Force vector, F = q V x B    E N turns Motoring B i vivi vv FpFp FF B i L Motor-generator Principles  i Both modes  i Both modes 14 Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com k = "EMF constant"

15 System Motoring and Regeneration Efficiencies "Ideal system efficiency" ignoring controller and all losses  system motor ≈  /(  b i) ≈  m  i / (  b i) =  m /  b = k  /  b  system regen ≈  b i / (  ) ≈  b i / (  m i) =  b /  m  =  b / (k  ) "Ideal system efficiency" ignoring controller and all losses  system motor ≈  /(  b i) ≈  m  i / (  b i) =  m /  b = k  /  b  system regen ≈  b i / (  ) ≈  b i / (  m i) =  b /  m  =  b / (k  ) Torque  m =k    RtRt bb System total resistance (*) AiAA 2010-483, Lundstrom, p.8 i Motor Regen Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com Typical controller pulse-width modulation (PWM) of duty cycle  and efficiency  ≈  0.25 (*)

Motor-generator & Battery ~ Performance Envelope and Data REGENERATION LMC "generator curve" 48V / 3,600 RPM k = 0.16 N-m/A R t = 0.041 Ohm LMCLTD.net MOTORING EEMCO 427D100 24V / 15,000 RPM k = 0.015 N-m/A R t = 0.075 Ohm CURRENT GROUP, i R t /  b TORQUE GROUP,  R t / (k  b ) Phil Barnes Apr-08-2011 i  16 100% Duty Cycle Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com THEO. EFFICIENCY, k  /  b  b /(k  ) Trends match theory Windprop synergy

Regenerative Electric-powered Flight J. Philip Barnes 18 Brushless "DC" Motor-generator ~ "Y" configuration Brushed Vs. Brushless Virtues, features, & limits Brushed : Theory foundation  i ;  k  ;  ki 2-wire interface Simplified control Brush maintenance ~120V limit (arcing) Low-speed cogging Brushed Vs. Brushless Virtues, features, & limits Brushed : Theory foundation  i ;  k  ;  ki 2-wire interface Simplified control Brush maintenance ~120V limit (arcing) Low-speed cogging N S Brushless : Inverter required 3-wire interface >1000V capable Minimal cogging Same as brushed:  i ;  k  ;  ki Brushless : Inverter required 3-wire interface >1000V capable Minimal cogging Same as brushed:  i ;  k  ;  ki

Equivalent DC machine 19 Brushless motor-gen. & inverter: Equivalent DC machine Brushless machine with inverter/rectifier as a system follows brushed DC machine principles:  =  m i ;  m = k  ;  = k i Both systems have 2-wire interface with the power circuit Brushless machine with inverter/rectifier as a system follows brushed DC machine principles:  =  m i ;  m = k  ;  = k i Both systems have 2-wire interface with the power circuit M-G bb i Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com  m  i motor or gen  m  i motor or gen Inverter- Rectifier  

Regenerative Electric-powered Flight J. Philip Barnes 20 Brushless "DC" Motor-generator ~ "  " configuration N S Features of "delta" winding* relative to "Y" or "star" Lower stall torque Higher maximum speed Best component efficiency, but likely requires a gearbox for a low-RPM "many-blade" prop, thus reducing system efficiency Features of "delta" winding* relative to "Y" or "star" Lower stall torque Higher maximum speed Best component efficiency, but likely requires a gearbox for a low-RPM "many-blade" prop, thus reducing system efficiency * Wikipedia, Brushless DC electric motor, April 2014

Gate voltage, V GE Regenerative Electric-powered Flight J. Philip Barnes 22 Transistor and flyback diode Collector Emitter Gate Flyback Diode ICIC V CE V GE iGBT MOSFET Gate voltage, V GE "High-tech, high-power light switch" Inverter commutation & DCBC boost adjust Lo-freq. (20-100 Hz) for commutation Hi-freq. (>10 kHz) pulse-width-mod (PWM) V GE (say 12 V) sets the collector current I C Collector voltage V CE (say 600 V) sets power Flyback diode for switch energy dissipation iGBT & diode unidirectional (via arrows) Transistor ~ 2V loss ; Diode ~ 0.7V loss "High-tech, high-power light switch" Inverter commutation & DCBC boost adjust Lo-freq. (20-100 Hz) for commutation Hi-freq. (>10 kHz) pulse-width-mod (PWM) V GE (say 12 V) sets the collector current I C Collector voltage V CE (say 600 V) sets power Flyback diode for switch energy dissipation iGBT & diode unidirectional (via arrows) Transistor ~ 2V loss ; Diode ~ 0.7V loss Gate voltage (V GE ) "opens the valve"

Regenerative Electric-powered Flight J. Philip Barnes 23 Inverter-rectifier ("inverter" for motoring mode) Each phase, per cycle: - Connect to battery voltage 120 o - Connect to ground 120 o - "Float" twice for 60 o each float Each phase, per cycle: - Connect to battery voltage 120 o - Connect to ground 120 o - "Float" twice for 60 o each float Inverter converts 2-wire DC to 3-wire "AC" Commutation toggles each phase 0-to-V B Inverter converts 2-wire DC to 3-wire "AC" Commutation toggles each phase 0-to-V B Switch pairs: one "upper" & one "lower“ Switch applies +15/-7V for iGBT on/off Avoid short circuit: Always "diagonalize" Switch pairs: one "upper" & one "lower“ Switch applies +15/-7V for iGBT on/off Avoid short circuit: Always "diagonalize" VBVB VBVB 1 2 3 1 2 3 -7V 15V S N

Regenerative Electric-powered Flight J. Philip Barnes 24 DC-to-AC conversion ~ "inverter" commutation waveforms AC basis Inverter "Dead time" avoids short circuit

Regenerative Electric-powered Flight J. Philip Barnes 25 Inverter-rectifier ("inverter" for motoring mode) ~ Snapshots VBVB VBVB 1 2 3 1 2 3 VBVB VBVB 1 2 3 1 2 3 VBVB VBVB 1 2 3 1 2 3 VBVB VBVB 1 2 3 1 2 3 "Upper" switch pairs diagonally with a lower switch Two phases are operating; one phase is "floating" "Upper" switch pairs diagonally with a lower switch Two phases are operating; one phase is "floating"

Regenerative Electric-powered Flight J. Philip Barnes 26 Inverter-rectifier ("rectifier" for generating mode) - iGBT EBEB 1 2 3 Rectifier converts 3-wire AC to 2-wire DC Battery is recharged via flyback diodes Diodes enable only two phases at once Commutation "ignored" (unidirect. iGBT) Rectifier converts 3-wire AC to 2-wire DC Battery is recharged via flyback diodes Diodes enable only two phases at once Commutation "ignored" (unidirect. iGBT) Snapshot E 1 - E 3 > E B 1 2 3 Current to battery! Diodes provide "free" regen! Diodes provide "free" regen!

Regenerative Electric-powered Flight J. Philip Barnes 27 Inverter-rectifier ("rectifier" for generating mode) - MOSFET EBEB 1 2 3 Rectifier converts 3-wire AC to 2-wire DC Charge battery via MOSFETs & flyback diodes Bi-directional: Comm. MOSFET assists diode Rectifier converts 3-wire AC to 2-wire DC Charge battery via MOSFETs & flyback diodes Bi-directional: Comm. MOSFET assists diode 1 2 3 E 1 - E 3 > E B Current to battery

Regenerative Electric-powered Flight J. Philip Barnes 28 Pulse-width modulation: Energy loss due to "chopping" At a given voltage, cruise current ≈ 15% of climb or accel current Superimposed on commutation: PWM "chopping" at cruise Typical switching frequency (f) for chopping ≈ 20 kHz (inaudible) Reduce the duty cycle (  ) to reduce average current (i av =  i on ) Energy is lost (iGBT & diode) with each on/off switching cycle Per-iGBT switching energy loss (S p ) ≈ 20 mJ per switching cycle Reduce chop losses: use PWM only on “upper” phase of 6-pack Cruise chopping loss = f S p = 0.4 kW = 20% @ 2 kW/phase At a given voltage, cruise current ≈ 15% of climb or accel current Superimposed on commutation: PWM "chopping" at cruise Typical switching frequency (f) for chopping ≈ 20 kHz (inaudible) Reduce the duty cycle (  ) to reduce average current (i av =  i on ) Energy is lost (iGBT & diode) with each on/off switching cycle Per-iGBT switching energy loss (S p ) ≈ 20 mJ per switching cycle Reduce chop losses: use PWM only on “upper” phase of 6-pack Cruise chopping loss = f S p = 0.4 kW = 20% @ 2 kW/phase Remove PWM from commutation; Incorporate DC boost converter Commutation voltage cycle Comm. + PWM superimposed i on i av       

DCBC: Key enabler, efficient bi-directional power management – Only the motoring mode is shown in the introductory graphic above “Boosts” DC voltage ~ 0-500 % with minor input/output ripple Power conservation: doubling the voltage halves the current Enables reduced battery totem pole length, i.e. Toyota Prius* DC voltage gain or “boost” is controlled by PWM “duty cycle” PWM used for DCBC gate current, not motor-gen main current Regenerative Electric-powered Flight J. Philip Barnes 30 DC boost converter enables efficient motoring & regen Boost battery voltage to efficiently drive the M-G as a motor Boost motor-generator EMF to efficiently recharge the battery M-G brushed or brushless with inv. C L VMVM VBVB PWM +15/-7V iGBT

Regenerative Electric-powered Flight J. Philip Barnes 31   ≡ duty cycle ;  ≡ period iGBT gate PWM DC boost converter – Equivalent circuits L di B /dt C dV M /dtVBVB iBiB iMiM VMVM iGBT off C dV M /dt L di B /dt iBiB VBVB iMiM VMVM iGBT on M-G brushed or brushless with inv. C L VMVM VBVB PWM iGBT

Regenerative Electric-powered Flight J. Philip Barnes 32 DC boost converter – Voltage gain & conversion efficiency L  i B2 /[(1-  )  ] C  V M2 /[(1-  )  ] VBVB iBiB iMiM VMVM Segment 2: iGBT off for  t = (1-  )  C  V M1 /(  ) L  i B1 /(  ) iBiB VBVB iMiM VMVM Time segment 1: iGBT on for  t =  [a] Voltage loop: V B - L  i B1 /(  ) = 0 [c] Output current: i M - C  V M1 /(  ) = 0 [b] V B - L  i B2 /[(1-  )  ] = V M [d] i B - C  V M2 /[(1-  )  ] = i M [e] PWM cycle:  i B1 +  i B2 = 0[f]  V M1 +  V M2 = 0 Voltage gain is set by duty cycle (  ) Efficiency = 1 (resistance neglected) Voltage gain is set by duty cycle (  ) Efficiency = 1 (resistance neglected) [g] Combine [a,b,e]:  V M /V B = 1/(1-  ) [h] via [c,d,f]:  i M /i B = 1-  Combine [g,h]:  ≡  i M V M /(i B V B ) = 1     ≡ duty cycle ;  ≡ period iGBT gate PWM

Regenerative Electric-powered Flight J. Philip Barnes 33 DC boost converter - efficiency and regen application "Evaluation of 2004 Toyota Prius," Oakridge National Lab, U.S. Dept. of Energy 233 Vdc in 5 10 15 20 kW Regen M-G Motor PWM iGBT C L VBVB DC boost converter integrates windprop and motor-generator Adjust PWM duty cycle to hold voltage gain as RPM decreases Efficient bi-directional power over a wide operating range DC boost converter integrates windprop and motor-generator Adjust PWM duty cycle to hold voltage gain as RPM decreases Efficient bi-directional power over a wide operating range Climb Regen Cruise

Regenerative Electric-powered Flight J. Philip Barnes 34 Circuit models, motor-generator efficiency, and current i b / G b  GbGb RhRh kk bb RhRh ibib a Motoring G m i b  GmGm RhRh kk bb RhRh ibib a Regen i b = [  b G b 2 - G b k  ] / [R h (1+G b 2 )] motoring i b = [k  G m -  b ] / [R h (1+G m 2 )] regeneration G ≡ DCBC voltage gain

Regenerative Electric-powered Flight J. Philip Barnes 35 Voltage Map - Motoring and Regen with DC boost converter Voltage %RPM Motor-gen EMF M-G, gain 2.0 M-G, gain 3.0 Battery, no boost Batt, voltage gain 2.0 Batt, voltage gain 3.0 Boost the battery for motoring Boost the M-G to regenerate Boost the battery for motoring Boost the M-G to regenerate Climb 220 Amps Batt: 540V M-G: 285V Capacity Regen -8 Amps Optimal Regen -11 Amps Cruise 35 Amps

37 Architectures compared "Chopper" architecture PWM main current chop Cruise: high chopping loss Regen: none or inefficient "Chopper" architecture PWM main current chop Cruise: high chopping loss Regen: none or inefficient Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com M-G bb i   PWM superimposed on commutation Inverter- Rectifier "Boost" architecture PWM sets DCBC boost Efficient motor & regen "Boost" architecture PWM sets DCBC boost Efficient motor & regen M-G bb i DC Boost Converter 2-way boost   PWM 12V Inverter- Rectifier Commutation

Regenerative Electric-powered Flight J. Philip Barnes 39 Regenosoar - Features and Design Rationale Counter rotors Symmetric flow Zero net torque Counter rotors Symmetric flow Zero net torque 8-blade rotors Low RPM, quiet, Low vibration Low tip Mach 8-blade rotors Low RPM, quiet, Low vibration Low tip Mach Ground handling No assistance req'd Winglet tip wheels Ground handling No assistance req'd Winglet tip wheels Pusher Config. Symmetry upstream Max. laminar flow Pusher Config. Symmetry upstream Max. laminar flow Compact power train Battery, motor-gen and powertrain Compact power train Battery, motor-gen and powertrain Pod-air-cooled MG & PE Regen parked in the wind With safety perimeter Regen parked in the wind With safety perimeter

40 Drag Coefficient, c D or c d 0.000.010.020.030.040.05 Lift Coefficient, c L or c l 0.00 0.25 0.50 0.75 1.00 1.25 1.50 Section and Vehicle Drag Polars Max L/D Min. Sink "Clean configuration" ~ Windprop System Removed Section Windprop System Removed Windprop System Removed Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com "Clean" aircraft

Load Factor and Turn Radius Airspeed, v_km/h 020406080100120140 Turn Radius, m 0 50 100 150 200 250 300 350 400 n n 1.1 1.4 1.2 1.05 Thermaling 1.6 r = v 2 (cos  ) / ( g tan  ) Load Factor and Bank Angle Load Factor, n n 1.01.11.21.31.41.51.6 Bank Angle  0 10 20 30 40 50  cos -1  cos   n n  Steady-state load factor ( n n ) ~ “g-load” and turn radius n n  L / w = cos  / cos  Glide: n n  1 Turn: n n  1 / cos  n n  L / w = cos  / cos  Glide: n n  1 Turn: n n  1 / cos  v L= n n w w   41 Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com * SAE 2004-01-3088 EQN 5.2, d  /dt = 0

42 Airspeed, v ~ km/h 5060708090100110120130140 150 dz/dt ~m/s -2.5 -2.0 -1.5 -0.5 0.0 g-Load, n n 1.0 1.2 Sea level 25 kg / m 2 A = 16 1.4 1.6 Min Sink Max L/D Load Factor and “Clean” Sink Rate “Clean” REGEN Windprop removed “Clean” REGEN Windprop removed Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com c L = n n w / (qs)

43 Steady-state climb or descent ~ New Formulation, New Insight L= n n w T-D  w  Glider, soaring bird, or "clean" regen T/D=0 (no thrust) Sink rate (-dz/dt) = n n (D/L)v With or without propulsion system Sink increases with g-load (n n ) D/L also increases with (n n ) Sink increases with airspeed (v) Glider, soaring bird, or "clean" regen T/D=0 (no thrust) Sink rate (-dz/dt) = n n (D/L)v With or without propulsion system Sink increases with g-load (n n ) D/L also increases with (n n ) Sink increases with airspeed (v) Regen operating mode T/D climb  6.3 cruise= 1.0 pinwheel glide  -0.1 efficient regen (thermal)  -0.4 capacity regen (descent)  -1.0 Regen operating mode T/D climb  6.3 cruise= 1.0 pinwheel glide  -0.1 efficient regen (thermal)  -0.4 capacity regen (descent)  -1.0 v  Derive steady-climb Equation Note: n n = cos  /cos  c L = n n w / (qs) Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com * SAE 2004-01-3088 EQN 5.2, d  /dt = 0

“Total Sink”  ≡ “Exchange Ratio,” as applicable: turbine system efficiency ~71% 1 / propeller system efficiency 0 for pinwheeling (no exchange)  ≡ “Exchange Ratio,” as applicable: turbine system efficiency ~71% 1 / propeller system efficiency 0 for pinwheeling (no exchange) “Total Climb” “Total Climb” Windprop Effect Windprop Effect “ Clean ” sink rate “ Clean ” sink rate Updraft Regen must have Updraft - or final descent High L/D, Low sink High sys. efficiency Regenerative Electric Flight Equation and Implications

45 Thermal Updraft Contours Total Energy = Kinetic + Potential Total Energy = Kinetic + Potential + Stored 1 o C warmer-air column 20-minute lifetime ~ solar power x 10 Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com U ~ m/s Elevation, z o ~ m 1 2 3 4

46 Climb and Regeneration in the Thermal (minimum-sink airspeed) Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com Climb rate Contours Energy rate Contours Equilibrium Regeneration Optimum Elevation, m

0.82 0.88 47 Regenerative Electric Flight Equation Applied for RegenoSoar Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

49 Regenerative Electric-powered Flight Windprop: 8 blades spin slow, quiet, & efficient DC & BLDC machines: EMF proportional to RPM M-G & battery verify theoretical efficiency trends Synergy of windprop & MG: Efficiency Vs. RPM - Optimum “speed ratios” ~ 85% & 115% by mode Popular "chopper" control: inefficient at cruise DC boost converter: efficient climb, cruise, regen Regen applications: – Thermal, ridge, wave, final descent,.... – UAV fleet, storm rider, earth observer,.... Give up 2% prop efficiency w/symmetric sections to gain perhaps 5-15% range and/or flying time Regenerative Electric-powered Flight Windprop: 8 blades spin slow, quiet, & efficient DC & BLDC machines: EMF proportional to RPM M-G & battery verify theoretical efficiency trends Synergy of windprop & MG: Efficiency Vs. RPM - Optimum “speed ratios” ~ 85% & 115% by mode Popular "chopper" control: inefficient at cruise DC boost converter: efficient climb, cruise, regen Regen applications: – Thermal, ridge, wave, final descent,.... – UAV fleet, storm rider, earth observer,.... Give up 2% prop efficiency w/symmetric sections to gain perhaps 5-15% range and/or flying time Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com M-G iGBT VMVM A "regen" is coming soon to an airport near you!

50 Phil Barnes has a Master’s Degree in Aerospace Engineering from Cal Poly Pomona and a Bachelor’s Degree in Mechanical Engineering from the University of Arizona. He has 33-years of experience in the performance analysis and computer modeling of aerospace vehicles and subsystems at Northrop Grumman. Phil has authored diverse technical papers on orbital mechanics, aerodynamics, gears, and according to the distinguished aerodynamicist Bruce Carmichael, a "landmark" paper clearly explaining how the wandering albatross uses its dynamic soaring technique to remain aloft indefinitely on shoulder-locked wings over a waveless sea. Whereas Phil's dynamic soaring presentation shows how the albatross exploits the vertical gradient of horizontal wind, this presentation shows how a "regen" aircraft would exploit vertical relative motion of the atmosphere, and brings together Phil’s broad- based knowledge of aerodynamics, flight mechanics, and aircraft subsystems with a passion for all forms of efficient flight. About the Author Regenerative Electric-powered Flight J. Philip Barnes www.HowFliesTheAlbatross.com

Regenerative Electric-powered Flight J. Philip Barnes 1 Regenerative Electric Flight Synergy and Integration of Dual-role Machines J. Philip Barnes 27.

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Regenerative Electric-powered Flight J. Philip Barnes 1 Regenerative Electric Flight Synergy and Integration of Dual-role Machines J. Philip Barnes 27.

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Presentation on theme: "Regenerative Electric-powered Flight J. Philip Barnes 1 Regenerative Electric Flight Synergy and Integration of Dual-role Machines J. Philip Barnes 27."— Presentation transcript:

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