The Search for Fuel Economy

Pages from a Designers' Notebook

Nov 11, 2008

The goal: 100 mpg at 70 mph, into a 20 mph headwind, with four bags of groceries. The Freedom Machine.
Chap. 21: Unexpected Problems
Getting closer to "one smooth, continuous streamlined shape"

The right side is now covered over. The windshield is fixed to the non-moving body and does not turn. The handlebars turn.

This is all new stuff.

You can see that there is an aluminum ring supporting the windshield. I will have to cut away the left side but I don't want to wait for that. I want to crawl in and go for a ride.

Errors showed up quickly.

After I wiggled inside this thing, I realized that I did not have my helmet with me. Worse, I had no way to reach out and pick it up! I tried to stand up but could not stand up. My shoulders are too wide to slip through the windshield opening. I am captured - a prisoner in my own contraption.

How did I miss this?

Oh well, I crawled out and put my helmet on and tried again. Hmmm. I cannot turn my head. My helmet wants to touch either side of the windshield. Just a little. No real problem right now but it will be annoying. OK lets hit the road. Right away, I can see that the windshield mounting flange is in the way of my vision.
Too tight for my helmet
Well, I am trying to be as streamlined as possible. Which means, being as enclosed as possible. I don't want a big windshield because it sticks up and is un-streamlined. The closer the windshield is to me, the smaller it can be. I made it too close.
Look at how small the clear part of the windshield is

With the small area and tight curve, .050" Lexan does the job without collapsing in the wind. It does a better job than any existing motorcycle windshield, too. The next speed bump was further evidence that the windshield is too tight at the sides. My shoulders banged into the bodywork. Face it... in a big bump, we need to be able to stand a little, to take the weight off our bottoms. I can't do this now. This is just another example of why it is a good idea to make it and ride it.

I head for the highways and winds. Where are all the flags?

Some readers have warned me that when the streamlining gets more complete, the effects of sidewinds will become more pronounced. As I get more enclosed, I loose track of the winds because I cannot feel them. I have to stick my hand out to feel for them. I used to watch for flags. In California, however, people don't seem to be displaying them much.

This trip, showed no change regarding wind effects. This is good.

Some observations:

With the right side smoothed over, air does not seem to want to come in from the left side. Maybe this is because it has no place to exit. Maybe, it in not cold enough today to feel what is happening.

If you recall, the last time it rained in California, I was running cardboard streamlining and could not ride in the rain. The rainy season is approaching California. I will learn a lot more when it rains.

It sure is un-nerving to not be able to swivel my head insde this thing. We really need to be able to turn our head around to safely ride a bike.

The headrest is too big. It is time to smooth out that area, too. Actually, I found a trick LED tail light...

It is back to the shop to fix these problems.
I leave you with this truth:

"Streamlining is easy to say but hard to do"

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This page posted Nov. 11, 2008