~conceptual design -...

1

Zamri Omar, UTHM

Design of A Propeller-Driven Airplane ~Conceptual Design

DR. ZAMRI BIN OMARDepartment of Aeronautical Engineering

Faculty of Mechanical & Manufacturing Eng.

Email : [email protected] : 4537618

Room: C08-01Mobile : 0127220907 (text only!!)

Congratulations…Welcome to UTHMPARIT RAJA….A Place To Be..

Zamri Omar, UTHM


~Conceptual Design

7 Pivot Points in Conceptual Design

� 1. Requirements

� 2. Airplane weight ~ First estimation

� 3. Critical performance parameters

� 4. Configuration layout

� 5. Airplane weight ~ Better estimation

� 6. Performance analysis

� 7. Optimization

Zamri Omar, UTHM


Conceptual Design ~1) Requirements

� Requirements for a new airplane are unique.

� Generally, for any new airplane design;

motivated by some established requirements

� RFPs by stakeholders, govts, military, etc..

� Customer request.

� Most GAs ~new design set by manufacturers.

� GAs ~ manufactures really studied their

customer needs.

� You, as the potential aircraft designer &

manufacturer ~ is given with this RFP

Zamri Omar, UTHM


Conceptual Design ~ A Case Study

Design of A Propeller-Driven Airplane

2

Zamri Omar, UTHM


� To design a light, business transport aircraft, pressurized cabin.

� Max level speed at midcruise weight : 250 mi/hr

� No. of passengers : 5 (+pilot)

� Range : 1200 miles.

� Ceiling : 25,000 ft.

� Rate of Climb at sea level: 1,000 ft/min.

� Stalling speed : 70 mi/h.

� Landing distance (to clear 50 ft obstacle) : 2,200 ft.

� Takeoff distance (to clear 50 ft obstacle) : 2,500 ft.

~(1) The Requirement

Zamri Omar, UTHM


� Wc : crew weight (pilots, cabin crews)

� Wp : payload weight. Passengers, luggage, fright, etc..

� Wf : fuel weight.

� We : empty weight. Airframe, engines, avionics, systems, equipments, etc..

~(2) Weight ~1st Estimation

� The takeoff gross weight, Wo;

efpco WWWWW +++=

)W/W(W/W(1

WW

oe)of

pc

−−

+= -------------------------(1)

Zamri Omar, UTHM


� (2.1) Estimation of We/Wo

� Evolutionary of previous existing airplanes � A New Airplane

� Needed : historical, statistical data of previous airplanes (parametric study)

� airplanes from 1930 - 2000Zamri Omar, UTHM


� For our 1st

estimate, we

choose;

62.0W

W

o

e =

3

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� (2.2) Estimation of Wf/Wo

� Statistics;

Airplane (L/D)max

Cessna 310 13

Beach Bonanza 13.8

Cessna Cardinal 14.2

� Reasonable approx for our

airplane � (L/D)max = 14

� Use Brequet’s range eqn;

159.0)W/W1(06.1W

Wo5

o

f =−= -------------(2)3

2p

W

Wln

D

L

cR

η=

� Based on mission profile;

Zamri Omar, UTHM


� (2.2) Calculation of Wo and Wf

� One-crew airplane � Wc = 170 lb

� Payload; 5 passengers + 20lb baggage per person + pilot baggage;

� � Wp = 5(170)+20(6) = 970 lb.

� From Eqn. (1)

� See the 4.525 amplification factor !

� From eqn (2),

� Weight of avgas is 5.64 lb/gal. So the tank vol should be;

Tank volume = 820 lb/5.64 = 145.4 gal = 661 litres ?

lb 158,5)525.4( 140,10.62-0.159-1

970170W

)W/W(W/W(1

WWo

oe)of

pc==

+==

−−

+

lb. 820lb) (5,158 159.0W159.0W159.0W

Wof

o

f ===⇒=

Zamri Omar, UTHM


~(3) Estimation of Critical Performance Parameters

� (CL)max, (L/D)max, W/S and T/W

� (3.1) Estimation of (CL)max

� Select the wing’s airfoil shape.

� Airfoil data : NACA, Clark, RF, Gottingen, Worthman, etc..

http://www.ae.illinois.edu/m-selig/ads/coord_database.html

� Many GA aircrafts use different airfoils at root and tip.

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� We choose ;

� at root : NACA 23018

� at tip : NACA 23012

� Average (Cl)max;

1.7

2

8.16.1)Cl( max

=

+=

4

Zamri Omar, UTHM




� To aid TO & Landing; add TE flaps � simple plain flap.

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� To aid TO & Landing; add TE flaps � simple plain flap.

� When flap deflected 45o �

� Average (Cl)max with 45O flap deflection =1.7 + 0.9 = 2.6

� To account 3D effect of finite wing, Raymer suggests (for AR >5);

�

9.0)Cl( max =∆

2.34

) (2.6 0.9

(Cl) 9.0)CL( maxmax

=

=

=

Zamri Omar, UTHM


� Here what STOL airplane can do !

~ 2009 STOLcompetition

~ Land & TO on a hill

Zamri Omar, UTHM



� (3.2) Estimation of (L/D)max

� Statistics;

Airplane (L/D)max

Cessna 310 13

Beach Bonanza 13.8

Cessna Cardinal 14.2

� Reasonable approx for our

airplane � (L/D)max = 14

5

Zamri Omar, UTHM



� (3.3) Estimation of wing loading, (W/S)

� W/S affects Vstall, Vmax, RoC, TO & LND distance, turn performance.

�

�

�

�

�

�

�

� FAR 23 : Vstall ≤ 61 kts ( mi/h = km/h)

⇒ρ

=∞ maxL

stall)C(

1

S

W2V -------------(3)maxL

2stall

)C(V2

1

S

W∞ρ=

0,D

0,D2

maxAmaxAmax

C

KC4]W/)T[(S/W](W/)T[(V

∞ρ

−=

-------------(4)

Zamri Omar, UTHM




� Required; Vstall ≤ 70 mi/h = 102.7 ft/s, ρ∞=0.002377 slug/ft3 (SL)

�

�

�

�

� This W/S is constrained by stall speed.

� How about W/S constrained by landing distance ?

⇒

ρ=

∞ maxLstall

)C(

2

S

W2V -------------(3)maxL

2stall

)C(V2

1

S

W∞ρ=

223 lb/ft 3.29)34.2()ft/s 7.102)(ft/slug 002377.0(2

1

S

W==

Zamri Omar, UTHM




� W/S constrained by landing distance.

�

�

�

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� Flight path radius during flare;

� Vf is average flare velocity, Vf=1.23Vstall

�

� Flare height is given by,

� Approach angle is assumed θa=3o for transport aircraft.

�

� Approach distance to clear 50 ft obstacle,

�

� Flare distance,

ft 477,2ft/s 2.32x2.0

ft/s) 7.102x23.1(

g2.0

VR

2

22f ===

ft 4.3)3 cos1(477,2) cos1(Rho

af =−=θ−=

ft 8893tan

ft 4.350

tan

h50S

oa

fa =

−=

θ

−=

ft 1303sin 2,477 sinRSo

af ==θ=

6

Zamri Omar, UTHM




� At SL, the total ground roll can be approximated as ;

�

� Required : 2,200 ft landing distance,

� From eq. (5),

�

�

� This W/S is greater than Vstall constrained W/S (29.3 lb/ft2).

� Look !, if W/S < 41.5 lb/ft2, we’ll obtain shorter landing distance (<2,200 ft)

� So we choose, W/S = 29.3 lb/ft2

S

W46.18

S

W4.65Sg +=

afgL SSSS ++=

ft 181,1889130200,2SSSS afLg =−−=−−=

-------------(5)

2lb/ft 5.41S

W

S

W46.18

S

W4.65 ft 181,1 =⇒+=

Zamri Omar, UTHM



� (3.4) Estimation of thrust-to-weight ratio, (T/W)

� T/W affects TO distance, RoC, Vmax

� To obtain the design value of (T/W), need to examine the effect of each

constraint on (T/W).

� Based on TO distance constraint, Total power needed, P ≥ 118.8 hp

� Based on RoC constraint, Total power needed, P ≥ 362.5 hp

� Based on Vmax constraint, Total power needed, P ≥ 303.1 hp

� So to satisfy all requirements, the engine should capable of producing max

power of 362.5 hp or greater.

� Power-to-Weight ratio,

�

� In term of power loading,

�

� (W/P)=14 is typical for GA (Raymer). So ours is very good !

lb/hp07.0lb 5,158

hp 5.362)W/P( ==

lb/hp 3.14hp 362.5

lb 158,5)P/W( ==

~conceptual design -...

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