Aerodynamics of Vehicles and Airplanes, and Hydrodynamics of Ships - Decreasing Fuel Consumption and Exhaust Gas Emissions in Transportation - page 110

Table 7.2 Elements of improved airframes with advanced aerodynamics
Flight systems
and flight deck

Structure
and materials

Propulsion
system

Aerodynamics Safety

and comfort

Fly-by-wire
On-Board
Measurement
Intelligent
navigation

Composite
materials
for fuselage
and wing
Cast aluminum door
Integrity of
structure

Use of prop-fan
Integration
of nacelle
and airframe
Use of un-ducted
fan engines

Slotted cruise
airfoil
Natural
laminar
flow

High safety for the
evacuation
of passengers
on land and water
Acceptance of
passengers
Compatibility
with airports

enhance lift and advanced winglets on outboard wings. Optimal construction
optimizes the lift to drag ratio by the use of sweptback or of wings with glider
construction. CFD design strengthens nacelles to improve fuselage and wing
surface smoothness to reduce drag.
A high bypass ratio leads to intensive turbulent air flow because large diameters
have a high air resistance. On balance, high bypass ratio engines provide a sig-
nificant gain for aircraft in terms of reduced fuel consumption and exhaust gas
emissions.

7.2.3 Airframe Concepts with Advanced Aerodynamics

Improved aerodynamic efficiency means a higher lift to drag ratio, slotted cruise
air foils and strengthened natural laminar flow [ 9 ]. New structural materials and
advanced airframe systems can contribute to the improvement; see Table 7.2 .

7.2.4 Wingtips and Riblets

The available width at airport gates may limit the allowable wingspan. Wingtip
devices improve the efficiency of fixed wing aircraft without extending length.
They reduce the aircraft's drag by altering the airflow near the wingtips; see
Fig. 7.4 .
Wingtips increase the efficiency of the payload of a middle range turbofan
driven airplane by 500 kg (1,102.5 lb) or by a distance of 185 km (100 nmi).
The saving of CO 2 can reach up to 700 t i.e., 1.5 9 10 6 lb per airplane per annum.
Wingtips also improve aircraft handling and reduce the wake turbulence hazard for
the following aircraft by approximately 3% [ 10 ].
Riblets are furrows in the direction of the air flow, which are added as a film
with a thickness of less than 1 mm (0.04 in) instead of paint on the surface of