Page 210 - Aeronautical Engineer Data Book

Aircraft design and construction 169

Estimate Estimate
gross weight power

Mission time Fuel capacity
Compare
Payload and crew weights

Check gross
weight

First estimate of disc loading

Main rotor tip
speed

Check First estimate of forward flight drag

Speed and climb
performance
requirements
Installed
power

Select engine(s)

Recalculate fuel requirement

Fig. 10.9 Helicopter design studies: the basic steps

10.4.1 Helicopter operational profile
For military helicopters, the operational profile
is frequently termed mission capability. The
relatively short range and low endurance of a
helicopter, compared to fixed wing aircraft,
means that the desired mission profile has a
significant influence on the design. Figure 10.10
shows a typical military mission profile.