The Search for Fuel Economy

Pages from a Designers' Notebook Readers comments

Chap. 2: CAD Streamlined Body Mar 8, 08

Before I begin designing a slippery body, I want to rebend the handlebars to fit me. Honda has pulled the bars back so as to not hit the windshield at full lock. I don't like the feel so I bent the handlebars into a comfortable position for me.   You can see that I had to grind notches out of the windshield. That is OK... I plan to replace whe windshield with a smaller one closer to me.

Over a period of a week, I bent the bars- rode it -and rebent the bars until they felt right to me. I like fatter grips, too. This is all subjective. These little revisions make the Helix feel right to me.  You may like Helix bars as is.  

Rebent handlebars
Streamlined shape: Air likes to go around this Demo

Air likes to go around one smooth shape, round at the front, pointed at the rear.  The perfect streamlined body would be exactly that.  But we have to get on and off our cycle, which means we need some kind of cut-out.  The air does not like to go around gaps or cut-outs. It causes fuel burning drag. Now it is time to determine the smallest cut-out necessary to get on and get off without affecting the streamlining too much.

I will make a mockup streamlined body from industrial foam board, made for sheathing walls of houses.  It is similar to the white foam board we can buy at art stores, but a lot cheaper and comes in 4’ x 8’ x 1/4” sheets, which is good. See my Cardboard muffler of 1965

Tha long tail is absoultely necessary for decent streamlining. But it is generally believed that a tail is responsible for handling problems in sidewinds. See Joe Petrali's experience with his tail in 1936. Read my analysis.

I want to get on the road as soon as possible to see what happens with a long tail. If it affects handling in a negative way, I need to know now, before I waste any more time.

All we need is a hot melt glue gun, foam board and a razor blade. I am trying to generate a smooth, continuous shape that has a streamlined profile: round at the front - pointed at the rear.
After tacking together the final shape from little pieces, I trace around it and cut a single piece from a fresh piece of foam board. Tracing is an easy way to cut two pieces... one for each side. I get on and off  all the time to be sure I will be able to ride this. No CAD (computer aided design) here. 
It is easier to leave the Helix windshield in place so I can go for a ride and see what we have. All the foam board has been hot melted to the Helix and attached with screws and tape.  
This page posted Mar 8, 08

Updated Nov 28, 2009

Chap. 3: Road Testing the Long Tail Mar 28, 08
Chap. 1: Streamlining Saves Fuel Feb 20, 08
Chap.2: CAD Streamlined Body Mar 8, 08
Chap. 4: Planking with Foam Apl. 5, 09
Chap. 5: More Wind Testing Apl. 7, 08
Chap. 6: The Final Shape Apl. 17, 08
Chap. 7: Decisions about Details May 10, 08
Page 8: Making the Center Bulkhead June 1, 08
Chap. 9: Rear Bulkhead and Truck bed June 8, 08
Chap. 10: Finish Rear and go for ride June 17, 08

If you have not yet watched my DVD, How they Got 470 mpg it is time to get it for the basic foundation for what we are doing here

Chap. 11: Finish the Tail June 29, 08
Chap. 12: Heading for Ohio, July 13-23, 08
Introduction to Fuel Economy
Chap. 13: Riding in the Midwest July 24, 08
Chap. 14: Vintage Days Ohio, July 25-7, 08
Chap. 15: Summary to date Aug 12, 08
Chap. 16: Adding Weight to the Front Sep. 1, 08
Chap. 17: Truth and Motorcycle Design Sep 4, 08
Chap. 18: Where should the weight be? Sep 25, 08
Chapter 19: Finishing the Streamlining Oct 14, 08
Chapter 20: Streamlining the Handlebars Nov 4, 08
Chapter 21: Unexpected Problems Nov 11, 08
Chapter 23: Getting my feet in and out Dec 19, 08
Chapter 22: Streamlining is working Nov 25, 08
Chapter 24: Streamlining is beginning to work! Jan 1, 09
Chapter 25: Tuft Testing Mar 2, 2009
Chapter 26: Starting Over April 9, 09
Chapter 27: More Ideas for Starting over April 20, 09
Chapter 28: Show time! Aug 1, 2009
Chapter 29: Getting the big parts right Dec 10, 2009
Chapter 30: First evaluation from an outsider Dec 20, 2009
Chapter 31: Visit with Allert Jacobs Dec 24, 2009
Chapter 32: Prius Headlights Jan 18, 2010
Chapter 33: New Gears Feb 17, 2010
Chapter 34: New Mileage Records April 25, 2010
Chapter 35: The Quail Gathering of Motorcycles May 9, 2010
Chapter 36: End of the line with the Helix June 19, 2010
Chapter 37: Vetter Challenge Oct. 9, 2010
Chapter 38: John Keogh helps out Dec 8, 2010
Chapter 39: Working with Keogh Dec 17, 2010
Chapter 40 and up (Work continuing in 2011)
Designing the Last Vetter Fairing

Chapters 1 thru 39 (2007-2010)

Chapters: 40 thru 51 (2011)

Chapters: 52 thru 61 (2012)

Chapters 62 thru 68 (2013)

Chapters 69-up (2014)