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

2. 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)

3. 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)

4. 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

5. Chapter 1
Aircraft Structure
General

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

7. 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

8. 항공기의 종류 (3)
글라이더 (Glider)

9. 항공기의 종류 (4)
고정익 항공기 (Airplane)

10. 항공기의 종류 (5)
회전익 항공기 (Rotorcraft-헬리콥터)

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

12. 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)

13. Aircraft Structure (Civil Aircraft)

14. 항공기의 세부 생김새 (2)
전투기의 생김새

15. 항공기의 세부 생김새 (3)
전투기의 생김새

16. 항공기의 세부 생김새 (4)
회전익기의 생김새

17. Aircraft Structure (Civil Aircraft)

18. 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.

19. Composite applications in the Boeing 787- year 2007

20. 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.

21. Aircraft Structure (Civil Aircraft)

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

23. Aircraft Structure(Military)

24. Aircraft Structure(Military)

25. Aircraft Development Process

26. Aircraft Development Process

27. Aircraft Development Process

28. Design for Manufacturing
Chapter 2
Design for Manufacturing

29. How an airplane is built?

30. Chapter 3
Aircraft Load

31. Aircraft Loads
Aircraft Loads :
Lift, Gravity
Thrust, Drag

32. Load Factors
n = Ltotal/W

33. Load Factors

34. 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. = ft/sec. = 1.852 km/h = 0.514m/sec,
1ft/sec = knot = mph

35. Atmospheric Properties

36. Atmospheric Properties

37. 3.2 Aeroelasticity

38. Aeroelastic Deformation

39. 3.3 Flight Maneuvers

40. 3.4 Basic Data

41. V-n Diagram

42. 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

43. V-n Diagram
x Ude

44. Total Airload Factor
A : Aspect Ratio
일반적으로

45. Aspect Ratio Parameter
A : Aspect Ratio
일반적으로

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

47. 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

48. V-n Diagram

49. Wing Design Loads

50. Wing Design Loads

51. Empennage Loads Horizontal Tail Loads

52. Fuselage Loads

53. Propulsion Loads
Landing Gear Loads

54. 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)
( for unmanned aircraft, spacecraft)
Margin of Safety (M.O.S) :
(Test Ultimate L-Ultimate L)/(Ultimate L)

55. 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 ,500 lbs.)/ 202,500 lbs.
= 40,500 lbs./ 202,500 lbs. = 0.2 = M.O.S
+ 20% margin
Wgtow : lbs
F.O.S. = 1.5
nmax = 9

56. Example of an Airplane Load Calculation