BSFC is the amount of fuel burned for the power produced. (Craig notes: Typical gasoline consumption is 1/2 pound of gas per horsepower per hour.)

Any internal combustion engine operating at it's torque peak is producing the most power for the amount of fuel burned. But larger displacement engines in a mild state of tune are more efficient up to the torque peak.

A diesel engine has a lower BSFC (Brake Specific Fuel Consumption) at it's torque peak than a gasoline engine.

It is true that a lower cg height and a longer wheelbase will decrease weight transfer but this is a good thing. This means more rear brake can be applied without lockup.

It’s also true that traction increases with an increase in weight on a tire. However, once the weight on a tire exceeds a relatively low amount (around 550 lbs is typical), the increase in traction is not at the same rate as the increase in weight, resulting in a net loss of traction. This is called a tire performance curve; a chart of lateral loading(traction) versus vertical loading (weight).

These points are documented consistently in books written by Allan Staniforth, Carroll Smith, Herb Adams, and Steve Smith.

Another factor is that the rider weighs more than the engine and gearbox. The cg may shift forward.

Another benefit of the low seating is the rider is much less likely to be thrown from the bike in an accident than a traditional bike.

I don't rememeber suggesting operation above the torque peak, but that is where the governor is usually set to. I have seen recent data that suggests that bsfc less than the bsfc at the torque peak can be had between 2200 and 3000 rpm.

Baumm was too low to see the road ahead.

The point is: We can sit too low.

At the ECO BRNO event last year, he outran all competitors (except two turbo models). Has great comfort with all the room and trunk space needed for two. He claims 300 miles on a battery charge @50MPH and 200MPH+ top speed. And less than a penny a mile fuel cost in Switzerland (where it is very expensive).

The summer of 2008, with gas at $4.50 per gallon, it would be 4.5¢ per mile.

1¢ per mile? At 70 mph, into a 20 mph headwind?

I don't believe it.

Long distance two passenger cruisers would be fully enclosed monocoque designs resembling a glider fuselage. Either a two or three wheel layout would work powered by a 3 cyl. diesel engine and a 3 phase electric motor. There are some kits on the market that could be starting points if side by sideseating is prefered.

David Bloom, has wrote a book called alcohol can be a gas. There is also a couple of clips of him being interviewed on youtube:

http://www.youtube.com/watch?v=Jew3ah24Zj4 also part two http://www.youtube.com/watch?v=9vq7km9TWL0

If you do have a look on the coates rotary valve website, i would recomend that you have a look at this video. cheers. billy. http://www.coatesengine.com/videos.html#

Frankly, I would rather eat the corn.

http://www.fueleconomy.gov/FEG/noframes/10747.shtml

The Civics usually run about 3300 rpm at 70 mph in 5th gear but get the best mileage between 55 mph and 65 mph. Geared so it turns just under 3000 rpm at 70 mph in a low Cd motorcycle, I think an engine of this size would (hopefully) have a little headroom so it did not have to run at full throttle. It should put out pretty close to the 15 ft lbs of torque with the right valve and cam design but I am not sure that it works out to enough horsepower at 3000 rpm. It could need a 500 cc engine to make enough power at this comparably low rpm.

I looked at over a dozen motorcycle and scooter engines between 200 cc and 500 cc. They all seem to be oversquare (larger bore diameter than stroke) high rpm and the motocross/offroad have high compression designs (over 11.0:1). I think an undersquare engine with higher torque at a lower rpm will give better mileage. Very few motorcycles or scooters have an advertised number over 70 mpg. I think this is because they are all oversquare designs. My guess is it has to do with the thermodynamics of an undersquare cylinder having a longer expansion stroke for a given displacement so you get more energy out of it. Higher rpm motors also seem to need more maintenance, like more frequent oil changes and more frequent valve adjustment.

I don't get it. I think you were doing some very clear thinking in picking a 250cc Helix for phase 1. Your results proved that it has just about the right power vs. fuel consumption balance. The shortcoming was the stability of the bike at high speed and the gearing of the transmission that prevented the streamlined bike from achieving the higher speeds that the engine was capable of providing.

Replacing the Helix' small wheels with proper 16 inch wheels would address both issues. The response curve of a CVT is easily modified by changing a few inexpensive roller weights and springs, but the final gear ratio is not - but can be achieved by changing to a larger wheel. The increased gear inches achieved with larger tires on the Helix should give you sufficient top end to go 75 comfortably, with the added "big wheel" stability you are seeking.

But the goal is to make a bolt-on streamlining kit, not to have to heavily modify or fabricate a new scooter chassis to fit large wheels on a small wheel bike.

Also, quite frankly I don't think any motorcycle frame is going to achieve the comfort and roominess you are looking for inside a small full streamlined shell, you need to stay with a scooter.

There are a number of big wheel 250cc maxi-scooters to choose from - and quite a few more if you count the ones that the major brands won't sell in the USA. But if you stick with what is commercially available in the US something like the very affordable and high quality Kymco People 250 might fill the bill - in stock form it gets 70mpg and it reported to top out at just under 80mph. Other contenders would be the Scarabeo 250 or the Piaggio BV250 - I know, the 500cc versions of these two scoots have been suggested, but I just don't believe the 500's are going to achieve the mpg you are looking for, despite rumors of "sweet spot" efficiency at half throttle.

Now I know that getting a stock 250 big wheel scooter might not achieve that taller final gear ratio that slapping a 16 inch wheel on a Helix would acheive - because their CVT's are spec'd for a 16 inch wheel. But if that final gear ratio isn't tall enough ... I wonder what would happen if you replace it with the CVT from a Helix?

If a bike only needed 3-5 HP instead of 15-25 horsepower to keep it going at highway speeds,

Vetter clarifies: Well, that was when speed limits were 55 and the rider was all squished into a tiny shell. Sitting up and comfortable at 70 mph means more like 15 hp.

the range of an electric motorcycle could be tripled, quadrupled, or even better. just like the gas mileage improvements.

Vetter comments: You are right. Electric vehicles need to begin with streamlining!

If an extra power pack could be added for longer trips to extend the range even further, the electric motorcycle could become an attractive method of transport. At least for me anyway.

I was thinking of the possibility of pulling an easy-towing add-on battery pack for longer trips either in the form of a narrow fin-shaped one-wheel backpack style trailer, or in the form of a "pusher-trailer" that also added it's own electric motor to help push the bike along in addition to the extra battery power.

Actually, we would be better off developing solar powered recharge stations... or battery exchange stations to serve the function of gas stations

When the bike was all by itself running in-town errands, it wouldn't need to be lugging around a heavier motor. Does that sound reasonable?

So in the first letter I was asking whether it would be more effective to try to blend the towed battery pack (trailer) right into the bikes streamlining bodywork, or if it would work better if the trailer was it's own separate streamlined package, slipstreaming behind the completely separate streamliner cycle that was towing it.

They would be incomplete shapes by themselves. but that is OK. The front would be for around town, generally slow. the rear gen set would complete the streamlining for the road where streamlining is more important.

Does it make a little better sense saying it this way?

Vetter says: I think the solution is in the above sketch.

Is it more effective to have one complete streamliner "drafting" behind another complete streamliner, or is it better to blend both together into one single long streamliner? (may flex in the middle at the trailer hitch)

Here is A GREAT DESIGN PROBLEM: The connection between the tow vehicle and the trailer: How do you articulate it and keep it smooth? You just might be the person to come up with the Great Solution.

The tail is looking a little tired. OriginallyI I had assumed that I would deflate it and stow it away for most riding. But, the tail is cool. So, I leave it on all the time. For the upcoming shows, I need to make it prettier.