Amateur-built and experimental aircraft - Australian Transport Safety ...

Wing loading and stall speed
Wing loading is an important measure of aircraft performance. As aircraft weight
increases for a given wing area, wing loading and stall speed increase. A lower
wing loading corresponds to a lower minimum velocity at which level flight is
possible. Wing loading is the maximum weight of the aircraft divided by the area of
the wing measured in kilograms per metres squared (kg/m 2 ) or pounds per square
feet (lb/sq ft).
Figure 36 records wing loading values, derived from the manufacturer and model
data, for 348 of 353 ABE aircraft surveyed. Wing loading is continuous data,
graphically represented in categories; for example the number 50 represents all
values between 26 and 50. This shows a minimum wing loading of 30 kg/m 2 and a
maximum of 159 kg/m 2 . Ninety per cent of aircraft in this survey had a wing
loading of less than 92 kg/m 2 , with the mean value being 72 kg/m 2 , and the median
value 71 kg/m 2 . The distribution of values in Figure 36 is skewed to the right
(having less values in the higher wing loading range). Aircraft with a low wing
loading generally have short take-off and landing (STOL) characteristics.
Figure 36: Wing loading
Although there were some aircraft with high wing loadings, the majority of ABE
aircraft had a similar wing loading to certified production aircraft. For example, a
standard Cessna 172 Skyhawk has a wing loading of 64 kg/m 2 , while a Piper PA-28
Cherokee has a wing loading of 70 kg/m 2 . Of the top 10 certified aircraft on the
CASA register with a similar type of aircraft configuration, Cirrus SR20 model
aircraft have one of the highest wing loadings at 104 kg/m 2 and the Cessna 210
Centurion has a wing loading of 105 kg/m 2 .
There are two different standards for wing loading in Australian ABE aircraft. In
the Experimental Category (CASR 21.191), wing loading requirements are not
specified, but the aircraft must be capable of flight. Amateur Built Aircraft
Approval aircraft are required to conform to one of two different design standards
where there is no acceptable data on stall speed; one standard for aircraft with a
certified aircraft engine (61 kts), and another for non-certified engines (55 kts).
Examples of STOL ABE aircraft on the VH- register are the Zenith CH-701, ICP
Savannah and Hornet Ag. A Van’s RV-6, the most common ABE aircraft on the
VH- register, has a wing loading of 71 kg/m 2 . Aircraft with higher wing loadings
are different models of Glasair, Lancair, and some canard aircraft. Historically,
wing loading in Australian ABE aircraft has increased, with the desire to place
larger horsepower engines in aircraft; this in turn increases the weight and therefore
- 47 -