Help me with DIY motorcycle fairing

[bennelson]

Hey Guys,

Now that the electric motorcycle goes 45 mpg, I am really starting to feel the effects of wind. (Plus my wife doesn't like the rougher ride at that speed)

Please help me with some ideas on how I can make some sort of aerodynamic fairing for it to reduce wind resistance and gain economy.

I was reading through an old motorcycle book and found some cool photos of fairings on British race bikes.(Cool sidecar racing too) Those fairings completely covered the front tire.

Something like this:


I am a bit inspired by the aero-CRX with the use of flexible plastic pipe and fiberglass.

My dad has been working on building wood canoes, so he has plenty of fiberglass materials around for that. I know that one of the earliest salt-flats racing cars actually used an upside-down canoe as the car body!


Perhaps I could design something with bent flexible tubing, cover it with fabric, and then fiberglass that?

Recumbent bikes have had "bodysocks" available to them for a while: a fabric stretched around the windshield and frame to smooth out aerodynamcs.


In the end, it would be nice to have a very light, rigid shell that would entirely cover the cycle. Then I would redo the head and tail lights custom with LEDs designed to fit that shell.

I would also like to fit a little bit of cargo space onto the cycle. Having no storage other than a backpack is a bit limiting. Even when I slapped the pizza rack on the back of the bike, it really did suddenly make a lot more usable space.

Here are a few designs I like:





I had one of those light cycles as a kid. Wish I still had it!!!

[ebacherville]

holly crap!! there is a dude in that thing!!!!

Cool but not very functional.. but sure would help, I know from my ninja 250 that if i tuck down and remain the throttle i gain a few MPH from the less wind resistance..

That shape is the ideal boattail shape.

[beatr911]

I've been pondering this very thing for a while now but for a 250cc cruiser with an ultra low seat height, kind of like an Alligator. So far I've found only two fairings available but both would need significant enough modification it would be just as easy to start from scratch anyway.

One is a classic "dustbin" reproduction like your sidecar pictures. http://www.airtech-streamlining.com/.../MV1751965.htm . The same company has gobs of race and reproduction fairings

The other is Craig Vetters reproduction Rifle body. http://www.craigvetter.com/pages/470...20fairing.html

[bennelson]

That Vetter fairing is pretty cool, but rather pricey for what I want to do.

I like the dustbin fairing. That's pretty slick. It still lets you get on an off the cycle in the normal manner, and put your feet on the ground!

[Ryland]

don't go to large or you will get poor handling, but a small windshield will tend to leave the rider in a dead spot of air where it is calmer and quieter, but the least aerodynamic part of a bike is the back.
if you wand a nice quite ride a good helmet can often be the best choice for the money.

[aerohead]

Do you want it to look like a production piece with beautiful compound curves or something more build-friendly?

[bennelson]

I would love beautiful compound curves, but I don't think that is within my amatuer skill level.

Lets shoot for build-friendly to start with!

[aerohead]

Originally Posted by bennelson

I would love beautiful compound curves, but I don't think that is within my amatuer skill level.

Lets shoot for build-friendly to start with!

Here's something I did on the CRX "cause I didn't know any better".I established some attachment points,constructed a light frame out of cedar(it's very easy to cut and fashion),held together with angle brackets.Then I skinned it with panels of cardboard using push-pins.I started taping the seams with 1-1/2 inch masking tape,as I removed the pins.When I was finished taping I had a complete shell mockup.I did wet lay-ups of bi-axial fiberglass cloth and polyester resin ( all from The Home Depot ).When I thought I had enough thickness,I removed the unit from the CRX and dunked it in a galvanized stock tank,let it soak,and the cardboard essentially dissolved away,leaving the fiberglass shell.Built without a mold it was sure rough but with successive coats of BONDO automotive body filler ( also from HD ) and a lot of grinding and sanding,I finally achieved something smooth enough to prime and paint.P.S. I used 1-mil poly painter's disposable drop-cloth at the interface of the car to ensure a release and not ruin the finish of the car.

[Otto]

Originally Posted by aerohead

Here's something I did on the CRX "cause I didn't know any better".I established some attachment points,constructed a light frame out of cedar(it's very easy to cut and fashion),held together with angle brackets.Then I skinned it with panels of cardboard using push-pins.I started taping the seams with 1-1/2 inch masking tape,as I removed the pins.When I was finished taping I had a complete shell mockup.I did wet lay-ups of bi-axial fiberglass cloth and polyester resin ( all from The Home Depot ).When I thought I had enough thickness,I removed the unit from the CRX and dunked it in a galvanized stock tank,let it soak,and the cardboard essentially dissolved away,leaving the fiberglass shell.Built without a mold it was sure rough but with successive coats of BONDO automotive body filler ( also from HD ) and a lot of grinding and sanding,I finally achieved something smooth enough to prime and paint.P.S. I used 1-mil poly painter's disposable drop-cloth at the interface of the car to ensure a release and not ruin the finish of the car.

Might be a good idea to leave the cardboard in, then skin the other side with more fiberglass. This makes a stiff sandwich structure.

Also, Google for Taylor paper glass, pioneered by homebuilt aircraft designer Molt Taylor. He used 90 lb. construction paper, skinned both sides with resin and fiberglass. BTW, Taylor was one of the best in the business, and his designs including the Taylor Air Car.

Another idea would be to use smooth foam board, the kind that has smooth paper facings on both sides over a foam core.

Keep in mind that often you are designing for stiffness rather than strength, per se. Double the thickness and you get 8X stiffness and 4X strength, which is the whole idea behind sandwich structures.

[bennelson]

I like the idea of using foam-core. It is pretty easy to cut into nice shapes, including curves, with a sharp razor knife.

Sometimes it can be had cheap, if you find a place throwing some out with beat-up corners or printing on it.

Sandwiching that in fiberglass sounds pretty easy - just a big sculpture project!