Chapt. 46: Streamlining a Ninja 250 Part 3
Sept. 15, 2011: We took advantage of the sun breaking thru the California fog to get this comparative picture of the Ninja 250 and Helix 250.
If you have been following along, you have read my comments about how big this first Streamlining Kit looks on the little Ninja 250. Well... we compared dimensions with my 24" wide Helix streamlining and discovered a little problem...

Somehow, the Body Framework structure was too wide. (5" too wide) Hmmm...

This was an easy fix. We just removed 5" from the center. This design is easily modified to fit any bike. At the same time, we took the opportunity to true up the 24" wide Body Framework structure using a laser.

Ever since my first fairings of 1966, which were all curves with no flat lines (to measure from), I try to design in an easily identifiable "reference plane."

The convenient Reference Plane on the Streamliner Body is a 90° angle. As a result, the rest of the structure has a true set of planes from which to measure.
Laser line shows true 90°

The importance of frontal area has been known for many years.

Read: A Tale of Two Wheels, below, for a little design history.

Typical wheels of the 1920s and 30s
Goodyear Air Wheels of the 1930s
Bob Reeve was a famous pilot in Alaska. Since I went to high school in Anchorage, I was aware of his fame as a bush pilot. At the beginning of WW2, Bob Reeve had a Fairchild 71 fitted with high pressure, large diameter tires that were standard for the time. Goodyear had introduced "Air Wheels" - do-nut shaped, low pressure tires, very much like the ATV tires of the 1980s, except smooth. They were supposed to allow landing in and takeoff from rougher fields. That sounded like they would be ideal for Alaska. Bob Reeve installed them on his Fairchild* only to discover that their increased frontal area caused enough drag to slow him down 5 mph. Normal cruise was supposed to be 105 mph. With the Air Wheels, he cruised at 100.

Air Wheels were more trouble than they were worth. He took them off.

Frontal area certainly plays a significant part in speed and fuel economy. My streamlined Helix will go 70 mph, into a 30 mph headwind. It "thinks" is is going 100 mph which is the cruising speed of a Fairchild 71. We can see from this story the effects of increased frontal area at that speed range. It is good that Alan and I spent the extra time to keep the frontal area as small as reasonable.

*Forgotten War Vol 3 Stan Cohen, Pictoral Histories Publishing Company, Missoula, Montana


It is always a good time to check to see that four bags of groceries fit
Some have commented that the Vetter Goals for carrying four bags of groceries are easy for me. But carrying four bags of groceries is not easy. It takes some clever design. Here Alan test fits the fourth bag in the space behind the wheel that I have not yet utilized.

I have wanted to use this space ever since I noticed it was there on my Helix.

It is time to figure how to mount the streamliner body on the little Ninja. I want three mounting points for simplicity of removal and maintenance. In addition, I want to see if we can use the space behind the rear tire to carry stuff.

The first step is to fabricate a thin sheet of aluminum to carry the load. Before making it out of real metal, I make it out of scrap milk carton paper and a hot melt glue gun. Above, we have determined the travel of the Ninja wheel plus 1" for clearance.

The next step is to make temporary side sheets out of 1/8" plywood, (called "doorskin plywood") to check the integrity of the structure. The plywood is stronger than the paper and cheaper than the aluminum. Suddenly, the Streamliner Body has become very solidly affixed to the Ninja.

"Staring at what we are doing" is an important part of the design process.
Important too, is keeping track of the goals like "carrying 4 bags of groceries." Three bags fit easily in the narrowed body but a 4th bag will have to be squished a bit. "Squishing" is not in the spirit of the goals of the Vetter Challenge.

We will have to use the space behind the rear wheel to hold the 4th bag properly.

The fourth bag will easily fit thru an access opening in the shelf.

Look at that cute little Ninja. We are adding more carrying capacity than any saddlebags could ever provide while, at the same time, streamlining it to burn less fuel. When finished, this will be a fine example of "living better on less energy."

We want to help make motorcycles better transportation.

Motorcycles can play their part in reducing our nation's thirst for imported petroleum.


Important reminder:

Saturday, Nov 19, 2011, Red Rock Casino, Las Vegas

The AMA has generously made available four places at the Motorcycle Hall of Fame Inductions Concours in Las Vegas to display Vetter Challenge Streamliners.

Alan and his streamlined Ninja will be there.

The next day, Sunday morning, ride with us to Barstow to test the suitability of the 160 mile route for a Final Vetter Challenge in the future.

Check it out and let me know if you would like to join us.

Master Index to the Last Vetter Fairing Story

Posted Sep 16, 2011

Updated Sep 19, 2011

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