Aero loss considerations (was RE: weight of the motorcycle)

[Roger Stockton <rstockton@delta-q.com>]

Jason (jhinton@howmet.com) and I continued the discussion of bike
vs passenger car aero losses off-list and, thanks primarily to Jason's
research efforts, have concluded that, broadly speaking, a bike will
likely have aerodynamic losses similar to or less than a typical passenger
car despite having a worse Cd figure.

The data Jason found to supports this is:

Suzuki GSX1300R  (World's Fastest Production Bike)
Cd = .56
Effective Frontal Area = 5.17 sq ft
CdA = 2.9 sq ft

Aprilia Mille  (Sportbike having the hot new "edge" styling)
Cd = .65
Effective Frontal Area = 5.25 sq ft
CdA = 3.41 sq ft

C5 Corvette
Cd = .29
Effective Frontal Area = 15.75 sq ft
CdA = 4.57 sq ft

Note:  Motorcycle Cd values measured with rider in full tuck position
Article was "Aerodynamics 101, What Looks Fast Isn't" by Steve Anderson.
The article states that the aero drag of the Aprilia is just 60% of that
of the C5 'Vette.

Just for comparison, Moto Guzzi's 1956 V-8 GP bike has the following
figures:
Cd = .45
Effective Frontal Area = 2.0 sq ft
CdA = 0.9 sq ft
This was back when motorcycle racing didn't have rules on aerodynamics.
The Moto Guzzi has a "dust bin" fairing that fully enclosed the front wheel.

This could certainly be useful information for someone considering a
motorcycle conversion, and needing to select a glider appropriate to their
planned mission.

Thanks once again to Jason for digging up this information!

Cheers,

Roger.