The Search for Fuel Economy

Pages from a Designers' Notebook

Freedom Machine
The goal: 100 mpg at 70 mph, into a 30* mph headwind, with four bags of groceries.
Chap. 29: Getting the Big Parts Right

Posted Dec 10, 2009

1967 Munro*
2009 Vetter
Streamlined for speed

112 horsepower pushed Burt Munro 183 mph

Without streamlining he went 148 mph

35/148=23% improvement in speed

Streamlined for burning less fuel

17 horsepower pushed me 75 mph

Without streamlining I went 62 mph

13/62=21% improvement in speed

*Current caretaker Tom Hensley
File this information away as basic truth
More truths:

Besides "Doing More with Less," streamlining offers more benefits:

I can carry more: Streamlining provides a huge storage space protected from the elements with no extra saddlebags! Mileage is unchanged.

It is more comfortable: I feel no wind. I don't need gloves. I don't need a jacket. I like riding this thing. Especially when it gets cold.

It does not slow down in the wind. I must put my hand out to check for headwinds. I am always surprised when it is forced back. There is no sensation of headwinds.

People do not pull out in front of me: I look big.

I am so passionate about streamling that I approached the FIM, presenting my case for allowing real streamlining on the tracks of the world. As a result, electric racers can be really streamlined. Rossi is next.
There are some problems with my streamlining:

It is awkward to get in and out of the "cockpit: In spite of my best efforts, am not happy about getting in and out of this thing. The windshield structure is in the way. This is because the windshield is cleverly attached to the non-moving part of the body. When I get on and turn the bars to the right, it does not open up a big space to get on. I am going to have to put the windshield onto the moving, handlebar part of the fairing so it can turn out of the way.

It is hard to push around: The streamlined Helix is still hard to push around because of the streamlining structure around the handlebar ends.

I cannot carry something in my lap: Because the area directly in front of me is filled with structure. This structure will go away when I redo the cockpit..

I cannot pick up anything from the right side. Having the right side totally closed in is great for streamlining but not very convenient for reaching out for things. I am going to have to open the sides up and figure out how to trick the air into thinking the gap is not there.

I cannot wave at other bikers: I cannot get my left hand out easily.

I cannot ride with my hands off the bars: One day, I wanted to see if it wobbled so I took my hands off the bars. You cannot ride hands free because steering is done by leaning. You cannot lean inside the body. You can push as hard as you want into the wall but it won't affect the steering. Strange that I never noticed it until now. Well, its a good thing I don't plan to road race this thing.

It is a little awkward to fill with gas. I must pull the flap open that my right leg sticks out of to get at the Helix filler. This problem will go away when I open up the sides.

I am constantly correcting for little gusts from sidewinds. This is my biggest issue. I can eliminate about 60% of the annoyance by pressing my right shoulder against the body in gusty winds. The gusts get transferred into my 180 pound body - which doesn't push around so easily - instead of having their way with the lightweight streamlined shell.

One day, awaiting my turn to turn onto a major road, the wind was blowing so strong that I almost could not hold it up! What a surprise. That same wind was going to be blowing on me when I rode it, too.

Take a look at what powerful sidewinds did to a moving train:

Maybe side area is the problem. Maybe I need to reduce side area.

Reluctantly, I decided to remove the sides
It is hard to destroy so many hours of work but I must try to solve the problems mentioned above. Removing the sides will reduce much of the massive side area. The plastic "Christmas Tree Fasteners make it easy. The gap should reduce the effects of the wind blowing from the side. However, much of my careful streamlining will be destroyed.

"Compromises, compromises. You want this? You gotta give up that."

Somehow I will have to "trick" the air I am travelling thru into thinking the sides are there. At the same time, I want side winds to pass thru the bodywork. Quite a challenge.

I removed the windshield from the "fixed"part of the body and attached it onto the handlebar portion. Now it turns with the bars making it so much easier to get on and off. It no longer feels like getting "in and out." I think this is good, too.

Much complexity is now gone. Simpler is better. It is definitely easier to ride. My knees don't hit the crossbar. Easier to push around, too. My sons (who are much bigger than me) will be able to ride it now, too.

Soon we'll see how it works on the road. Bottom of this page.

Temporary aluminum stringers determine where the new skin should go.
Card stock template
Real aluminum part
Revising the body:

Since the windshield now turns with the bars, we must generate a surface to extend rearward - as far as we can - while not restricting access. The new surface will follow the sweep generated by the aluminum stringers.

One of the major problems has been not being able to push it around. We'll fix that now. The "U" shaped cut outs should make it easier to grab the bars.

At the last minute, I wrapped the tail opening with a 4" plastic flex tube to see if there is still room. The idea is to eventually curve the forward edge to encourage the air to pick up smoothly.

It was time to be off to Las Vegas and the AMA Hall of Fame inductions at the Hard Rock Casino:
The First Vetter Fairing (1966) and the Last Vetter Fairing (2009)
With a Magic Marker, I wrote all over it with answers to most questions. I invited people to sit on it to get a feel of the machine of the future. These kids won't forget this.
David Hough, longtime motorcycle safety proponent, had fun in the "Last Vetter Fairing" Dave and I spent an hour discussing motorcycle safety and side car safety. He definately knows his stuff. That evening, David was inducted into the Motorcycle Hall of Fame.

Congratulations, Dave.

Dec 26, 2009: The results of alterations to my bodywork:

In a attempt to reduce the effects of sidewinds, I removed the right side skin between the front and back. I also removed all the structure needed to attach the windshield to the fixed body I remounted the windshield in exactly the same position on the part that turns with the bars. Now the windshield swings away, making the machine easier to get on and off.

It was in the low 30s this morning. Cold air helps me to "Read" the wind. My observations:

Ease of use: It is now easier to get on and off. I can push it around easier. My feet go in and out easier. It is now easier to fill it with gas. It has gotten easier to operate this thing.

Riding comfort: The windshield does not do the comprehensive job it did before. The air wraps in quicker now. I will have to make it about an inch higher to deflect the wind from my face. Before the change in the side, my legs did not feel any cold. Now, I can feel slight air movement.

The air also wraps into the gap (that wasn't there before), making my back cold. It will help to move the seatback about 5" forward. Making the radius smooth should help. Right now, it is all ragged.

Results in the wind: This is the most encouraging result. I no longer feel the little side gusts. The air coming through the gap may not be quite as comfortable but it deals with sidewinds much better.

"Compromises, compromises. You want this? You gotta give up that."

Maybe. I have some ideas.

Master Index to the Last Vetter Fairing Story

This page posted Dec 10. 09

Revised May 17, 10