DR2Stability and Control Preliminary Design

Review and Performance PDROctober 24, 2000

Presented By: Christopher Peters

…and that’s cool

Team DR2Chris Curtis

Loren GarrisonJeff Rodrian

Mark Blanton

S+C, PERFORMANCE PDR

DR2S+C, PERFORMANCE PDR Presentation Outline:

• Stability and Control– Empennage sizing– Control Surface Sizing– CG, AC and NP Locations– Trim Discussion– Static Margin– Dutch Roll Mode– Short Period Mode

• Performance– Take-off and Climb– Turn– Endurance

• Projected Plan

DR2S+C, PERFORMANCE PDREmpennage Sizing:

• Class I Sizing Approach– Sizing with Tail Volume Coefficients

• Vvt,Vht – ROSKAM II, SEC8– Vvt = 0.04

– Vht = 0.5

• Determined from Historical Data for small GA Aircraft, Homebuilt and Production.

• VT area generally too big…

• Need Class II Sizing to justify Size Selection– HT and VT analyzed using Class II Sizing

DR2S+C, PERFORMANCE PDREmpennage Sizing:

• Class II Sizing Approach– HT

• Size HT using Center of Gravity (CG), Static Margin (SM), Tail Volume Coefficient (Vht) and HT-Moment Arm (lht) Information.

– VT• Size VT using CG, Cnβ, Tail Volume Coefficient

(Vvt), and VT-Moment Arm (lvt) Information.

DR2S+C, PERFORMANCE PDR

Empennage Sizing HT:

• For Electric Model Design assume the ability to pick CG by internal arrangement of Avionics and Electronics, to fit Desired SM

• Pick SM to fit Mission

• Modification of X-Plot Method necessary

• Analyze HT for Trimmed flight and Geometry Limitations

DR2S+C, PERFORMANCE PDR

Empennage Sizing HT:

• SM, 18% is Design Goal

• Possible Travel to Account for: 10%-25%– Due to Component Shift and Mission Modifications

• Neutral Point Location (Xnp) Determined thru Trim-Analysis

• CG Set

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S+C, PERFORMANCE PDR

Empennage Sizing HT:

• Neutral Point Derivation:

• Calculation of lht by Sht Variation – Limited by Length of Fuselage:

ht

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DR2S+C, PERFORMANCE PDR

Empennage Sizing HT Solution:

Sht = 2.25ft2

ARht = 4bht= 3.0 ftcht = 0.75 ftVht = 0.5lht = 3.171 ft

DR2S+C, PERFORMANCE PDR

Empennage Sizing VT:

• Vvt Variation for Svt Calculation determined by Weathercock Criterion for ‘Manned Aircraft’:

• Simultaneously Calculation of lvt by Vvt Variation –

– Iteration Process, Cnβ update – Effects on Dutch Roll Mode

• Weathercock: Cnβ >= 0.057 rad-1

vt

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DR2S+C, PERFORMANCE PDR

Empennage Sizing VT Solution:

Svt = 0.77ft2

ARvt = 2.5bvt= 1.39 ftcvt = 0.56 ftVvt = 0.024lvt = 3.38 ft

SvtHIST = 1.69ft2

DR2S+C, PERFORMANCE PDR

Control Surface Sizing :• Control Surface Sizing thru Class I Method:

– Estimation based on Empirical Data• From ROSKAM II/8 and former 451 Reports:

– Elevator: 40%croot – 45%ctip , Full Span– Rudder: 35% croot - 48% ctip, Full Span– Aileron: 25% cw – 60% Span

– Deflection Limits: • Rudder/Elevator: +/- 10º

– Flat Plate Airfoil Approximation – Separation

– No Dihedral, Rudder and Aileron Control

DR2S+C, PERFORMANCE PDR

Aerodynamic Center, CG, SM:

• Aerodynamic Center Wing– 23% of Cmean – For Biplanes (Raymer)

• Aerodynamic Center Aircraft– As shown Before, Xnp = 1.85ft (from FS 0, - Nose of A/C)

• CG– SM = 18%, CG = FS 1.68

– SM = 10%, CG = FS 1.75

– SM = 25%, CG = FS 1.61

DR2S+C, PERFORMANCE PDR

Aerodynamic Center, CG, SM:

• CG Calculation, Mass Inertias– Component Shift to meet SM = 18%

– Determine Mass Inertias for given CG

– Ixx = 0.5 slugs-ft^2

– Iyy = 0.54 slugs-ft^2

– Izz = 0.96 slugs-ft^2

DR2S+C, PERFORMANCE PDRTrim:

Force and Moment Balance

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DR2Moment Coefficient:

S+C, PERFORMANCE PDR

iwu= 0 degiwl= -2 degiht= 0 deg

DR2Trim Conditions

S+C, PERFORMANCE PDR

DR2S+C, PERFORMANCE PDR

Trim Conditions

DR2S+C, PERFORMANCE PDR

Dutch Roll Mode:

ζDR = 0.212

ωDR =2.102

DR2S+C, PERFORMANCE PDRShort Period Mode Approximation (after DR K. Hout):

ζSP = 0.57

ωSP =5.62

DR2S+C, PERFORMANCE PDRPerformance

• Endurance– After propulsion PDR II

• Endurance Requirement met and exceeded at Vloiter=25 ft/s

• Takeoff Distance– Less than 35 ft

– At Climbangle > 6deg.

– Easily meeting abort mission and climb constraints

DR2S+C, PERFORMANCE PDRPerformance

• Projected Work– Detailed Analysis of Performance Parameters

• Take-off

• Turning

– Dynamic Simulation of Aircraft

– Mission Analysis with finalized Parameters