1. Configuration Design part 2 Wing Placement

2. HIGH WING:PROS 1. Quick loading and unloading. C-5, C-17  Loading and unloading through nose / tail doors: important to have low floor level.  Low-wing ac: main deck floor is 16-17 ft (5 m) above the apron because the wing carry-through structure passes below the floor. Necessary to have special loading and boarding equipment. 2. Best for braced-wing monoplanes. Cessna  Struts cause little interference when attached to the lower side of the wing.  Lighter struts because they are stressed in tension. 3. The wing is generally lighter.

3. C-17

4. Cessna 152

5. HIGH WING:PROS 4. The nose-wheel gear is shorter and lighter. 5. Best for STOL QSRA  Close proximity of the wing to the ground during TO and LNG may cause pronounced undesirable ground effects.  Required ground clearance for large, fully deflected TE flaps and large props would entail a very tall and heavy LG in a low wing configuration. 6. Safer.  Damage and fire risk is limited during a forced LNG. 7. Less Ground Effect in CTOL Shorts 330  Smaller LNG distance. 8. Best for amphibians Boeing 314-A  Keeps engines away from H 2 O.

6. Quiet Short Research Aircraft

7. Shorts 330

8. Boeing 314-A

9. HIGH WING:CONS 1. Problem w. the retraction of the main LG.  In small, high-wing propeller ac, main LG can be retracted into engine nacelles (Fokker F-27) or in tail booms (Hawker Siddeley Argosy). In large ac, however, this would make the LG too tall and heavy.  A solution for large ac: fuselage-mounted LG.  Problem 1: strengthening of the fuselage structure required for the transmission of the LNG impact results in W increase.  Problem 2: with a fuselage mounted main LG the track may not be sufficiently wide. 2. No ground effect in CTOL.  Increased TO distance.

10. Fokker F-27

11. Hawker Siddeley HS.660 Argosy

12. HIGH WING:CONS 3. No room for underfloor cargo.  Fuselage section below the floor is flattened to reduce LG height + keep the floor low (4-4.5 ft = 1.2-1.4 m).  Solution: longer cargo hold in cabin.  Problem 1: longer fuselage.  Problem 2: large cg travel. 4. Unsafe  Fuselage will sink when ac is forced down on water. Provisions must be made for escape through the cabin roof. 5. Not good for highly maneuverable ac.  Too stable in roll.

13. HIGH WING:CONS 6. ~ 20% more S V than a low-wing configuration. 7. OEW is generally higher. 8. Structural design is generally more complicated.

14. MID WING:PROS 1. Min D in high-speed flight. (fighters, trainers)  Surfaces at wing / fuselage junction meet at 90 0 angles; interference between BLs at low  is minimized.  Fuselage section at the location where the wing is mounted is roughly cylindrical; divergence of airflow over wing root is minimized. 2. Best maneuverability. 3. Wing can be continuous through the fuselage  transfer of loads from the wing can take place via almost solid “bulkheads”, to which each wing-half is attached.

15. F-18 Hornet & T-37

16. MID WING:CONS 1. Reduced internal useful fuselage volume.  That is the reason why mid-wing configurations are not adopted for transports.

17. LOW WING:PROS 1. Efficient use of fuselage under-floor space. 2. Large tail angle allows for optimum rotation during TO (especially for stretched versions). 3. Easy retraction of main LG between wing spars. 4. Safer.  A low wing and possibly the engines attached to it form a large energy absorption mass during a forced LND. 5. Favorable ground effects.  Decreased TO distance.  AC lands itself; little or no elevator movement required to flare out because L increase results in nose-up pitching M. 6. Better maneuverability than a high wing.

19. LOW WING:CONS 1. Unsafe.  Potential fire hazard during forced LND when wing and engines hit the ground. 2. Unfavorable ground effects.  AC floats during LND; longer LND distance. 3. Greater elevator deflection required for TO rotation and LND flare out.  Decreased downwash on the tail results in nose down pitching M. 4. Longer LG especially on swept back wings, to provide tip clearance during TO rotation.