The Search for Fuel Economy

Pages from a Designers' Notebook

July 13-27, 2008

Chap. 13: Illinois, Ohio and Vintage Days
On my final test ride before leaving, Carol noticed that the winds were denting in the front. This thin, yellow plastic was a little too thin. Too late to do anything about this. Reluctantly, I loaded it on my trailer and headed for Illinois and Ohio.
What's this?
Looks suspiciously like my 1966 Vetter Design logo.
100 degree Illinois heat further deformed the plastic
It got worse...
Illinois tornado-like winds blew it over early in the morning
These are some of the reasons why a designer of motorcycles should also ride. We get to experience the REAL problems of riding before you do. Better I deal with these problems than you, right? Altho the tail was gone, the yellow plastic was undamaged.

These disasters don't happen at home in Carmel. We just burn in California.

Time for a new foam tail
Thin, lightweight plastics and a lot of foam are the future if we are to "Do more with less". Here my brother, Bruce helps to make a new foam tail that weighs 3 pounds.

Remember... for good handling, the weight needs to be at the front... not the rear.

This tail is intended for highway use, and is held on with bungee cords. For in-town riding, we don't need it and leave it off. Without the tail, the bike is as long as a regular Honda Helix.

Brother Bruce on his 21 hp Yamaha set up to challenge my 18 hp Helix Streamliner
Bruce tricked out his XT225 with narrow drag bars and rear mounted footpegs. Look at his rear sprocket: 39 teeth! With a 17 tooth front sprocket it was geared for 125 mph. Of course, it could not go that fast. Actually, it maxed out at 75 mph. Not bad for 21 hp. Laid out like this, all his weight was on his tummy, so Bruce made a giant pillow to lay on. He called it his Speed-Bag. Our new foam tail is rough, but works to streamline the air, bringing it back to a point.

In impromptu drag races on the flat Illinois roads, Bruce on his 21 hp Yamaha could slightly out-accelerate me on my 18 hp Helix. But I was gaining on him at the end. If the road had not run out, I would have passed him. We did a 120 mile mileage challenge ride into Indiana and back to Illinois.

In 1967, we took the same roads to Colorado
In those days, we rode 34 hp, 350cc Yamahas that got 40 mpg at 65 mph. We liked the power. Today, in 2008, we want mileage. Today, our speeds were 65-70 mph. The winds were stiff. It was in the 90s. The fuel had 10% ethanol.

We began at a grain elevator scales where my Streamlined Helix, with me on it, carrying about 50 pounds of gear, weighed in at 590 pounds. Bruce and his Yamaha, carrying nothing, weighed 470 pounds. I sat up. Bruce hunched over. Bruce knows the value of minimum frontal area. I know the value of comfort. I am older.

The results:

Bruce beat me

But not by much. These mileage figures are no better than stock! How disappointing. Bruce discovered that it hurt too much to ride like this and is going to return his Yamaha to stock. Well, Aldus Huxley once said:

"The truth will make you mad"

61.25 mpg. vs. 62.9 mpg.
Why did we get such poor mileage? In my own fuel Economy contests of the 1980s, didn't I get 107 mpg? There was no time to cry about it right now. I had to leave.
Time to ride to Ohio
The ride would be a good time to ponder it all. I filled my storage space with my presentation equipment and headed east on I-70 at 70 miles per hour. The winds were awful, blowing generally from the north so hard that the flags were straight out.

Speeding semi-trucks were troublesome. I had learned months ago that I could feel the winds more as I added streamlining. On this trip, my first with the nose covered over, there were some really worrysome moments when I got sandwiched between two speeding semis in the worst cross winds. We don't like this situation on any motorcycle. But I must admit, the effects of sidewinds and passing semis is worse on my streamliner. I ran pretty much wide open all the way. My mileage was around 56 mpg in these conditions. (with 10% ethanol)

Packing for the ride.

What is going on?

First, regarding mileage, my bike is not yet streamlined. I departed California unfinished because I simply ran out of time. Streamlining is one, smooth, continuous shape. This ain't it, yet. The body is still full of holes and gaps. I can only conclude that we will not see any consistantly measurable improvements in reduced fuel consumption until the streamlining is complete.

But what about the semi trucks and sidewinds on those midwest interstates?

The worst effects came from the winds blowing on the un-finished side of my bike... from the left. Will it get better when I cover the sides? I don't know. Most of you expert readers think it will get worse as the side is smoothed over. I do know this: The tail extension seems better than without it. The nose seems to have more effect.

Top fuel economy pioneer, Matt Guzzetta, offers a clue.

In 1984, Matt set a world's record, driving his 12 hp Vetter Fuel Economy Suzuki from Los Angeles to Daytona on 11.5 gallons of fuel, averaging 215 mpg for the trip. The speed limits in the US were 55 mph (until 1990) which is one of the reasons I got 107 mpg in my own contest, years ago.

Matt added 70 pounds to the front of his Suzuki and sidewind problems diminished

Matt had built a special, extra 10 gallon tank up front. Gas weighs about 6 pounds per gallon, which means he had about 70 pounds of extra weight up front. See more in the August, 1984 Motorcyclist magazine. In my interview with Matt, he explained that with that extra weight up front, the effects of sidewinds were dramatically reduced. The effects of winds increased as the fuel burned off. This is a clue as to what can be done.

"For good handling, the center of pressure needs to be at the rear and the weight up front"

Matt Guzzetta's comments to me are recorded on my DVD:

"How They got 470 mpg"

When I return to California, I will hang some lead off the front and see what happens. In the meantime, I was not prepared to be mobbed in Ohio.

This page updated Aug 2, 2008