Idea: Full span flaps

Full span flaps with flapped ailerons:

In board wing has 60% span fowler flaps. Outboard wing, the remaining 40% consists plain flap type flaperons with similar mechanism than used in Mini-Sytky.

deltaClmax_fowler = 0.6 * 1.67 + 0.4 * 0.9 = 1.362

For airfoil with Clmax 1.2 the maximum Clmax on landing configuration is thus 1.32 + 1.362 = 2.68

This allows smaller wing area and higher wing loading to be used without sacrificing takeoff and landing performance too much.

Another variation with single slotted flaps:

deltaClmax_singleslotted = 0.6*1.18 + 0.4*0.9 = 1.06

+1.06 in Clmax still is a very good value and better that would be obtained with full span flaperon (+0.9). For airfoil with Clmax of 1.32 this yields Clmax of 2.37.

This idea has not been tested in practice and is not guaranteed to work.

Effects on aircraft:

Aircraft with 60% span plain flap and Wortman FX 38-153 (no full span high lift device):

Clmax = 1.3 + 0.9*0.6 

deltaClmax = 0.54

Clmax => 1.84

86 hp required for 200 kts cruise

wing loading: 92 kg / m2

wing area: 7.2 m2

stall speed: 55 kts

design cruise: 200 kts

Cdtot = 0.011 (with boundary layer suction)

Same aircraft with full span flaperon and Wortman FX 38-153:

Clmax = 1.3+0.9 =  2.20

Same aircraft parameters:

76 hp required for 200 kts cruise

wing loading: 110 kg / m2

wing area: 6 m2 

Aircraft with full span flaps with slotted inboard section:

Clmax = 1.3 + 1.06 = 2.36 

Same aircraft parameters:

74 hp required for 200 kts cruise

wing loading: 118 kg / m2

wing area: 5.6 m2

Aircraft with full span flaps with fowler inboard section:

Clmax = 1.3 + 1.362 = 2.66

70 hp required for 200 kts cruise

wing area: 5 m2

wing loading: 134 kg / m2

For the most extreme case theoretical savings over usual configuration:

Power = 86-70 = 16 hp (18%)

wing loading: 134-92 = 42 kg/m2 (31%)

wing area: 7.2 m2 - 5 m2 = 2.2 m2 (30%)