National Aeronautics and Space Administration

Fundamental Aeronautics ProgramSubsonic Rotary Wing Project

V i bl S d R t ft D i S t R h

Dr. David G. LewickiResearch Mechanical EngineerRXN/Tribology & Mechanical Components Branch, Glenn Research Center

Variable-Speed Rotorcraft Drive System Research

Mark Stevens, Mechanical & Rotating Systems Branch, Glenn Research CenterHans DeSmidt, Associate Professor, University of Tennessee

2012 T h i l C f

1www.nasa.gov

2012 Technical ConferenceMarch 13-15, 2012

https://ntrs.nasa.gov/search.jsp?R=20150010357 2018-07-06T12:58:22+00:00Z

Background

High speed

Variable-speedVariable-speedpropulsion (50%)

References:References:• Johnson, W., Yamauchi, G.K., and Watts, M.E.,

"NASA Heavy Lift Rotorcraft Systems Investigation", NASA/TP-2005-213467, Rept-A-0514419, December 2005.

• Acree, C.W., Hyeonsoo, Y., and Sinsay, J. D.,

Applications:Applications:• Large civil tilt rotor• Joint heavy lift

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“Performance Optimization of the NASA Large Civil Tiltrotor” International Powered Lift Conference, London, UK, July 22-24, 2008.

• Unmanned air vehicle

Objective

Develop variable-speed drive

t t h l i f t ftsystem technologies for rotorcraft

applications to allow 50% speed

change of rotors with minimal

impact on weightimpact on weight.

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State-of-the-Art

• Most current rotorcraft operate at fixed speed.p p• V22: 15% speed change, slowing down engine.• A160 Hummingbird: two-speed transmission,

relatively heavy.• Automotive: heavy, not enough power capacity.

• Innovative speed change technology requiredInnovative speed change technology required, continued drive system weight reduction required.

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Approach

• Development of variable-speed transmission test facility (in-house).

• Development of variable-speed transmission concepts (in-house, industry).

D i d li f i bl d d i• Dynamic modeling of variable-speed drive systems (NASA NRA, Penn St, Univ. of Tennessee).)

55

• Development of variable-speed transmission test facility (in-house).

• Development of variable-speed transmission concepts (in-house, industry).

D i d li f i bl d d i• Dynamic modeling of variable-speed drive systems (NASA NRA, Penn St, Univ. of Tennessee).)

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GRC Variable-Speed Transmission Test Facility• Dual-motor (driver & loader) facility configuration: allows versatility in allowable

designs available to test.• 15000 rpm input speed, 7500-15000 rpm output speed (0-50% reduction ratio).

M t 140 ft lb f 0 7500 200 h f 7500 15000• Motor power: 140 ft-lb from 0-7500 rpm, 200-hp from 7500-15000 rpm.• Power regenerative motor configuration.• State-of-the-art motor controllers & PLC's.• Allows scripted speed, torque, & clutch loading profiles.p p q g p

77

GRC Variable-Speed Transmission Test Facility

88

Facility Validation Tests Completed

• Successfully operated at fulloperated at full speed & torque.

• Successfully demonstrated prescribed speed & torque control.

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GRC Variable-Speed TransmissionTest Facility

Facility Check-Out Test Results

Milestone: (SRW.01.01.108) Complete Fabrication, Assembly, and Check-Out of Variable-Speed Test Facility: 2-23-12

• Development of variable-speed transmission test facility (in-house).

• Development of variable-speed transmission concepts (in-house, industry).

D i d li f i bl d d i• Dynamic modeling of variable-speed drive systems (NASA NRA, Penn St, Univ. of Tennessee).)

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Configurations To Test

1) Offset Compound Gear Drive w/ Dry Clutch.

2) Offset Compound Gear Drive w/ Wet Clutch.

3) Double Star Idler Planetary w/ Dry Clutch.

4) Double Star Idler Planetary w/ Wet Clutch4) Double Star Idler Planetary w/ Wet Clutch.

1 Stevens, M.A., Handschuh, R.F., and Lewicki, D.G., "Concepts for Variable/Multi-Speed Rotorcraft Drive System", Proceedings of the 64th American Helicopter Society International Forum, Montreal, Canada, April-May 2008 (also NASA TM-2008-215276, Army Research Laboratory Report ARL-TR-4564, AHS Paper No. 080273).2

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2 Stevens, M.A., Handschuh, R.F., and Lewicki, D.G., "Variable/Multispeed Rotorcraft Drive System Concepts", NASA TM-2009-215456, Army Research Laboratory Report ARL-TR-4758, March 2009.

Offset Compound Gear Drive

Output gear

Gear cluster

Input gear

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"Offset Compound Gear Inline Two-Speed Drive", U.S. Patent No. US 8,091,445 B1, Jan 10, 2012.

Offset Compound Gear Drive w/ Dry Clutch

Offset compound gear drive

Dry clutchSupport bearing

Support bearing

Lubedistribution

bearing

Input Output

1313Fixed stations

Clutches

Dry Clutch Wet Clutch

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Double Star Idler Planetary

Planet star gearPlanet idler gear

Input gear

Ring gear

1515

• Development of variable-speed transmission test facility (in-house).

• Development of variable-speed transmission concepts (in-house, industry).

D i d li f i bl d d i• Dynamic modeling of variable-speed drive systems (NASA NRA, Penn St, Univ. of Tennessee).)

1616

Drive System Dynamic Modeling

1717

Two-Speed Tiltrotor Driveline

Left Nacelle(Twin Two Spool Gas

Turbine Engines)Initial

Ratio, ni

Dual Clutch TransmissionnDCT,low &nDCT,high Final

Ratio, nf

Left RotorLeft Nacelle(Twin Two Spool Gas

Turbine Engines)Initial

Ratio, ni

Dual Clutch TransmissionnDCT,low &nDCT,high Final

Ratio, nf

Left Rotor

NASA LCTR-2NASA LCTR-2

FWU

FWU1:1

FWU

FWU1:1

FWU

Cross-Shaft

ForwardSpeed

Blade Pitch

Clutch Engagement

Pressure Inputs

Multi-EngineFuel Control

FWU

Cross-Shaft

ForwardSpeed

Blade Pitch

Clutch Engagement

Pressure Inputs

Multi-EngineFuel Control

FWU

Blade PitchControl

Pressure Inputs

FWU

Blade PitchControl

Pressure Inputs

• DCTs upstream from cross-shaft

FWU

Right Nacelle InitialFinal

Ratio n

1:1

Dual Clutch

FWU

Right Nacelle InitialFinal

Ratio n

1:1

Dual Clutch

• Maintains rotor indexing phase

1818

Right Nacelle(Twin Two Spool Gas

Turbine Engines)

Initial Ratio, ni

Ratio, nf

Right Rotor

TransmissionnDCT,low &nDCT,high

Right Nacelle(Twin Two Spool Gas

Turbine Engines)

Initial Ratio, ni

Ratio, nf

Right Rotor

TransmissionnDCT,low &nDCT,high

Comprehensive Propulsion System Model

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Sequential Shift Control – Downshift

SSC Downshift Sequence:FWU

F l

SSC Downshift Sequence:1. Disable GTE torque sharing

control loop2. Left side DCT downshift3 Ri ht id GTE d Fuel

Control3. Right side GTE ramp-down4. Right side DCT downshift5. Right side GTE ramp-up6. Re-enable GTE torque

Fuel Control

qsharing control loop

Advantages: FWUFWUFWUAdvantages:• Always under engine

power• Avoids clutch engagements

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Reference: Litt, J.S., Edwards, J.M., and DeCastro, J.A., “A Sequential Shifting Algorithm for Variable Rotor Speed Control,” NASA/TM 2007-214842 (2007).

g gunder full power

Downshift Example Results

Set point

ActualActual

Right rotorLeft rotor

High speed clutch

Low speed clutch

Low speed clutchHigh speed clutch

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Downshift Example Results

Ri h i

Left engine

Right engine

L ft tRight rotorLeft rotor

2222

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