It gives information about designing balsa RC planes.

2. ADVANTAGES
 Provides safety from stall spin at low altitude.
 Load Sharing- Reducing Main wing area.
 Main wing spar can be Out of the way.
 Smaller, Lighter ,more compact airplane.
2

3. DISADVANTAGE
• Heavily loaded fore plane.
• Limited aerobatic capabilities.
3

4. AIRFOIL SELECTION
• Forewing must stall first.
• Main wing must attain
Angle of Zero lift first.
4

5. E124 is better for forewing.
E168 is not good choice for
both forewing and
mainwing.
E197 is good for Main wing.
5

6. ADVANTAGES OF
SLOTTED FLAPS ON
FOREPLANE WING• Stall angle reduced.
• CL is increasing.
• Reduced Zero Lift angle.
6

7. REYNOLDS NUM, ASPECT
RATIO & PLANFORM
• High ARs reduces stall angle (needed for
foreplane).
• High ARs results into lower RNs. So also Landing
speed reduces.
• Chords of less than 5 inches are avoided.
• Low ARs increases stalling angle (needed for main
wings).
• Shorter Main wingspan improves roll response.
• Forward sweep on foreplane promotes to that wing
stall first.
• In Three surfaced wing its beneficial for horizontal
tail plane.
• Forward sweep in forewing should not more than 5 7

8. DOWNWASH AND TIP
VORTICES
•FOR CANARDS
•Downwash reduces lift
on aftwing at the
downwash area of
forewing .
8

9. • For Tandem Wings
• Whole span on the aft
wing is similarly
affected.
9

10. IN 3-SURFACED PLANES
• Horizontal Tail is affected by
the downwash or reduced
angle.
• For tandem wings of equal
span the aft wing’s AoA
should be increased by the
down wash angle
generated by fore plane
• For Canard’s and three
surface airplanes
shadowed portions of the
main wing should have an
increase in AoA that’s equal
to the downwash of the
Fore plane.
10

11. JOG
• Region of main
wing which is
out of
downwash.
• Gives
adequate lift.
11

12. LOGICAL DESIGN STEP
• PU and CU selection.
• Weight Estimation from previous Graph.
• Wing loading selection.
• For level-flight speed front and aft wing’s AoA need to be
known.
• The NP and CG location.
• Total wing area must be divided into to part.
12

13. 13

14. Smaller the fore wing
farther apart the
NP and CG or vice
versa.
14

15. CANARDS
• If flaps are used need some balancing lift. Causes problem in
pitching moment as dive or stall.
• Both sets of flaps must be extended simultaneously for balancing.
• For small canard like 15% aft wing area needs more powerful flap
and also disadvantage is that in shorter tail moment arm.
• This can be solve by sweeping back the aft wing. And placing
vertical surface at the wingtips.
• Sweepback reduces lift.
15

16. TANDEM WINGS
• NP and CG should be
well forward.
• Pusher engine is kept
just behind the front
wing.
16

17. THREE SURFACED
PLANES.• Effect on front and aft wing will be same.
• NP and CG will be rear ward(compared to
canard).
• Need to be considered-
 ARs and Planforms.
 Longitudinal and vertical separation.
 Airfoil selection.
17

18. THREE SURFACED
PLANESI. Aft and main wing provides all the lift
needed and elevators control pitch and
trim.
II. Canard wing share most of the lift with
horizontal tail.
18

19. LONGITUDINAL
CONTROL METHOD• Slotted flap would be better for dominant
pitch control.
• Flap on the forewing and simultaneous up
or down action of aileron.
• For tandem wings partial span of forewing
or plain flap would be better.
• For three surfaced plane tailplane’s
elevator controls the pitching moment.
19

20. DIRECTIONAL CONTROL
• Vertical tail design and spiral stability.
• Tandem and 3 surfaced planes have enough TMA
for adequate sized surfaces.
• Canard doesn’t have sufficient TMA.
• Recourse is that-
• Larger vertical surfaces.
• Aft wing sweepback
• Wing tip vertical surfaces.
20

21. FLAPS
• Flaps needs to be strong as both the aft
and front wing provides lift.
• Extension must not upset the lift distribution
bw wings.
• Both side of flaps must be lowered
simultaneously .
21

22. • Flap
deflection
reduces the
stalling
angle for
both front
and aft spar.
22

23. 23

24. CERTAIN THINGS WE
DISCUSSED EARLIER
• Dihedral
• Landing gear.
• Structural design.
24

25. PLOVER.
25