비행체 구조설계 Aircraft Structural Design 윤 광준 교수(Prof. KJ Yoon) 항공우주정보시스템공학부 (Dept. of Aerospace Information Eng.)

Purpose of Course The design method of the aircraft structure after understanding aircraft loads. Students can get an ability to design a basic aircraft by surveying the existing aircraft structure and designing a real aircraft structure. Text Book : Airframe Structural Design (Author: M.C. Niu, Conmilit Press) Korean Reference Book : 항공기구조설계 (권진회 등, 경문사)

Lecture Method Formal Lecture with text book and PPT/Video files (8 weeks) Example of Aircraft Structural Design (3 weeks) Special Project for Aircraft Structure Design/Manufacturing (5 weeks)

SPECIAL PROJECT Design for given design requirements Selection of aircraft to design Sizing of wing and fuselage Basic structural & aerodynamic analysis Presentation of design result

Chapter 1 Aircraft Structure General

비행한다는 것의 의미 (1) 날개가 필요하다. 힘도 필요하다. 멋지게 나는 것, 멀리 나는 것도 있다

비행한다는 것의 의미 (2) 비행한다는 것의 의미 장거리 여객 수송/화물 수송이 가능해짐 지구 밖의 행성까지 탐사가 가능해짐 인공위성을 이용한 통신, 방송, GPS활용 등도 가능해짐 국가안보를 위해 항공기의 활용도 가능해짐 …………… 비행한다는 것의 의미

항공기의 종류 (3) 글라이더 (Glider)

항공기의 종류 (4) 고정익 항공기 (Airplane)

항공기의 종류 (5) 회전익 항공기 (Rotorcraft-헬리콥터)

비행한다는 것의 의미 (3) 양력(Lift)-날개 추력(Thrust)-엔진 공기저항(Drag)-동체 중력(Weight)

잘 날기 위해서는? (21) 조종의 원리: 조종면을 이용하여 날개에서 발생하는 양력의 차이를 이용 수직 꼬리 날개 (Vertical Stabilizer) 방향타 수평꼬리날개 (Horizontal Stabilizer) 주 날개 (Main Wing) 승강타 엔진 (Engine) 에일레런 플랩 동체 (Fuselage)

Aircraft Structure (Civil Aircraft)

항공기의 세부 생김새 (2) 전투기의 생김새

항공기의 세부 생김새 (3) 전투기의 생김새

항공기의 세부 생김새 (4) 회전익기의 생김새

Aircraft Structure (Civil Aircraft)

Composite applications in the Boeing 777--1990s The Boeing 777 is around 20 percent composites by weight, wing’s fixed leading edge, the trailing-edge panels, the flaps and flaperons, the spoilers, outboard aileron, floor beams, the wing-to-body fairing, and the landing-gear doors. Using composite materials for the empennage saves approximately 1,500 lb in weight.

Composite applications in the Boeing 787- year 2007

Composite applications in the Airbus-A380 CFRP : rear spars, rear pressure bulkhead, the upper deck floor beams, and for the ailerons, spoilers and outer flaps. 22 % wt.

Aircraft Structure (Civil Aircraft)

Aircraft Structure(Boeing 747) Wing Span : 59.6m Length : 70.6m Weight : 174 ton

Aircraft Structure(Military)

Aircraft Structure(Military)

Aircraft Development Process

Aircraft Development Process

Aircraft Development Process

Design for Manufacturing Chapter 2 Design for Manufacturing

How an airplane is built?

Chapter 3 Aircraft Load

Aircraft Loads Aircraft Loads : Lift, Gravity Thrust, Drag

Load Factors n = Ltotal/W

Load Factors

Atmospheric Properties Unit : lb/ft 2 = The knot is a unit of speed equal to one nautical mile per hour 1 knot = 1.151 mph. = 1.687 ft/sec. = 1.852 km/h = 0.514m/sec, 1ft/sec = 0.592 knot = 0.681 mph

Atmospheric Properties

Atmospheric Properties

3.2 Aeroelasticity

Aeroelastic Deformation

3.3 Flight Maneuvers

3.4 Basic Data

V-n Diagram

V-n Diagram VA : 설계운동속도 VA = VS VS : Stall Speed VC : 설계순항속도(design cruise speed) VD : 설계급강하속도(design dive speed) VD > 1.25VC 되어야 함

V-n Diagram x Ude

Total Airload Factor A : Aspect Ratio 일반적으로  

Aspect Ratio Parameter A : Aspect Ratio 일반적으로  

Vari. of Lift-Curve Slope Parameter A : Aspect Ratio 일반적으로  

V-n Diagram VA : 설계운동속도 VB : 최대 돌풍에 대한 설계속도 (대략 VD/2) VC : 설계순항속도(design cruise speed) VD : 설계급강하속도(design dive speed) VD > 1.25VC 되어야 함

V-n Diagram

Wing Design Loads

Wing Design Loads

Empennage Loads Horizontal Tail Loads

Fuselage Loads

Propulsion Loads Landing Gear Loads

Aircraft Critical Loads Limit or Applied Load(제한하중) The largest load the aircraft is actually expected to encounter. Ultimate or Design Load(극한하중) The highest load the structure is designed to withstand without breaking (for three seconds). # Ultimate Load = F.S. x Limit Load (F.S. : Factor of Safety, usually it is 1.5) ( 1.25 for unmanned aircraft, spacecraft) Margin of Safety (M.O.S) : (Test Ultimate L-Ultimate L)/(Ultimate L)

Aircraft Loads Wgtow : 30.000lbs F.O.S. = 1.5 nmax = 9 Example A fighter aircraft has a gross take-off weight of 30,000 lbs. In a test of one wing, the wing fails at a total loading of 243,000 lbs. What is the margin of safety? Definition of M.O.S. = (Tested Ultimate – Ultimate)/Ultimate We know: Tested Ultimate = 243,000 lbs. (for one wing) How do we get the Design Ultimate? Design Ultimate = Design Limit x Factor of Safety For aircraft, F.O.S. = 1.5 How do we get the Design Limit? Use the v-n diagram, From U.E., max n for fighter = 9 = limit n (Note: n for level flight = 1 ⇒ loading for level flight = weight) ⇒ Design Limit = nlimit x weight = 9 x 30,000 lbs. = 270,000 lbs. But, each wing carries 1/2 of this Design limit load for one wing = 135,000 lbs. ⇒ Design ultimate load for one wing = 135,000 x 1.5 = 202,500 lbs. Finally, M.O.S. = (243,000 lbs. - 202,500 lbs.)/ 202,500 lbs. = 40,500 lbs./ 202,500 lbs. = 0.2 = M.O.S + 20% margin Wgtow : 30.000lbs F.O.S. = 1.5 nmax = 9

Example of an Airplane Load Calculation