Draftbags

Aerobag 5

This version is produced from a more complete CAD toolchain, including both design and CNC-cut tooling. Compared with the 4.5 version, it implements a more streamlined downward slope on the rear, coinciding with airflow streamlines. Interior volume is marginally increased. The shape was parameterized in terms of width and vertical taper, and multiple foam model variants were fabricated and drag tested. Drag tests found no performance advantage in narrower-than-rider or vertically-tapered forms.

Construction is from thermoformed ABS plastic. For the initial builds this design employs a rack mounting using the Racktime Snapit system, with the rack height modified to reach optimum vertical position of the bag. This positions the bag at the proper height without resorting to a riser on a "standard" rack. A generic flat base on the bag can accomodate different mounting interfaces.

Edit Note: Here include photos of interior, handle carrying, taillight mounting.

Edit Note: Here include photos of riding in use.

Following are reference photos of solid foam mockups used for shape development and aerodynamic test.

Aerobag 4.5

Prototype formed from fully molded construction. Hundreds of miles of ride testing for functionality, durability and aerodynamic drag. This has been a good workhorse platform. It has supported a lot of business commuting, shopping, and family fun. It is a little klunky and overweight with the stacked 2x4 wood spacers.

Aerobag 4

Designed with semi-useable volume, partly thermoformed construction. Road tested for miles.

Aerobag 3

Also based on CFD studies. Carved foam faced with lycra shape model, not a hollow, functional bag. Drag test measurements exceeded break-even versus a no-bag configuration. This design includes the "nose" section under the saddle, which is an optional implementation per the patent. The nose does improve drag, but at considerable cost in mounting and fabrication complexity.

Aerobag 2

The first version based on CFD studies. Solid core shape model, not a functional luggage carrier. Smaller than originally intended, minimal testing performed.

Aerobag 1

Generally correct idea but too big, not streamlined enough. Foam core and carved foam construction. Improved drag versus panniers.

Aerobag 0

Built around a bucket. Kind of embarassing.