Designing and Building my own High MPG Car

[ConnClark]

So since this is an economy car and you won't need a lot of power. you could build a lot of it out of balsa wood and styrofoam then just coat the out side with fiber glass when your done.

[GoGogebic]

I'm not saying that a trike wouldn't be fine around town or at low speeds in the snow and ice. I'm just not convinced I would want to be doing 75-80 mph on the interstate when only the tire tracks from the other cars are iceless. Just think about the white knuckles you'll have fighting the back end as it moves around in the ice while the front two tires are on dry pavement. Maybe if you run blizzaks for tires you might be fine, but there not the best for mpg. The only way I'll be convinced is if I see a motorcycle running the center of the lane at 80 mph in the dead of winter on ice.

[NeilBlanchard]

Originally Posted by Patrick

Looks like an Edison2. You might want to take a look at their designs as they probably have solved a lot of the problems already. Edison2 - Welcome

The biggest challenge with the Edison2 VLC is the suspension, and how to keep the wheel fairings steady while the wheels move up and down underneath. Or, you could go like the Aptera and then it is best to have all the struts be airfoils.

Don't forget about the pivot space of the front wheels -- the trailing length of the fairings must be a compromise if they hit the sides of the main chassis.

Also, something that is hard to anticipate is the air interaction between the main chassis and the wheel fairings.

A concept of safety that I learned from Oliver Kuttner (owner of Edison2) is deflection. Their VLC is shaped like an elongated diamond, so as to deflect (as opposed to engage with) an outside object in a crash. The outboard wheels are able to absorb energy and then tear away. Look at F1 cars as a model for crash worthiness.

You need to design around a drivetrain; and you need to have cooling if you are using an ICE.

[GoGogebic]

Thanks everybody for your input.

The suspension won't be based on the Edison 2, but I totally agree with the idea of deflecting impacts.

Stay tuned, I definitely think this car is going to surprise you.

[ConnClark]

Although it would look strange, you could still do a three wheeler with an offset rear wheel that tracks behind one of the front wheels. That would solve your snow problem.

[GoGogebic]

A lot of people seem to be really into trikes. I know they can be registered as a motorcycle, but this can't be the only reason. If people are suggesting I offset the rear wheel and turn my car into a three legged dog there must be more reasons. What are they?

[ConnClark]

A short list of economy benefits of a trike.

1. Lower rolling resistance.

2. Reduced rotational mass.

3. Less aerodynamic drag from the wheels.

Of course there are safety and stability penalties.

[brucepick]

Originally Posted by GoGogebic

Please comment on what you think about the idea of a single seater. I feel it can really make the car a lot cheaper to build and much more aerodynamically efficient. Of course, I am planning on have storage for about 4 bags of groceries.

Depending on cost I might be OK with a single seater. But consider making it a tandem 2-seater, one in front and one in rear. That way you still have the narrow profile of a single seater. Maybe arrange the rear seat design so that you only have the full 4-bag capacity with the second seat empty (maybe collapsed). That way the car might barely be bigger than the 1-seater with 4-bag capacity.

As for the 3-4 wheel debate that's appeared here, I'm all for 4 wheels. Any benefit it gives you in stability and traction will be very welcome indeed. This car is pretty radical as it is (4 wheels) when you compare it to anything else in mass production. I say let it have a full set of four wheels.

I've attempted to ride a bicycle in a few inches of wet snow and that was NOT easy.

[Big Dave]

I’m warming to the idea of the reverse trike, but it has to stay with the leaning vehicle dynamics of the motorcycle to avoid the tendency of the rear wheel of a flat-cornering reverse trike to whip around (ground loop.)

http://www.youtube.com/watch?v=OYy8KiH-Jtg

http://www.youtube.com/watch?v=Bu6wxKs-XGM

http://www.youtube.com/watch?v=tHXKuFcOF-0

Clearly, the Harley is the most advanced of these (there are others out there). With the driver sitting behind the engine and the passenger in a tandem position (traditional for motorcycles) the next step is to fair this rascal in. The other two are add-on kits. The Harley has the rider sitting low. Harley sells a lot of bikes so people can get on and off them easily and set flat-footed at lights so this is a natural for them. I like the low driver position because that way you can get minimal frontal area without putting the driver into an uncomfortable semi-recumbent position.

By using the motorcycle vehicle dynamics you lean the machine into the curve or wind fairly easily by tilting and letting the change in center of gravity do the work.

Some other thoughts.

Such a machine has to have a reverse gear. The only bike I know of that has a reverse is the Honda Gold Wing.

The “Harley" layout lends itself to having a long-travel sprung seat like 18 wheelers have. Most motorcycles have limited suspension travel and after a day in the saddle your kidneys have had it.

Once faired in, you could add a heater using engine oil or coolant, making the machine a three season motorcycle. Got my doubts about snow or ice. Somebody else can be the test pilot.

The engine/transmission does not have to be from a motorcycle. VW is beginning to market TDIs with six-speed dual clutch transmissions. This solves the reverse problem. You could go front wheel drive, or use a system of timing belts to drive the rear wheel and achieve the optimum gearing.

Accommodating the steering and tilting front wheels will drive the body designer to drink.

[sgtlethargic]

I drive alone an overwhelming majority of the time; I like the idea of a single-seater. I'm planning on building one from mostly vintage car parts.

Lighter weight + smaller frontal area => better city and highway MPG. I think it'll be easier for me to lower the A value of Cd*A then the Cd value. Lowering the Cd is even better.

(14 sq ft)*(0.32) = 4.5 sq ft of drag area

The GM EV1 is 3.95 and the Honda Insight is 5.1 according to Wikipedia:
Automotive aerodynamics - Wikipedia, the free encyclopedia

If you sit in the center you can be further away from the door than with a regular width car, which should offer better side-impact protection. I plan to have more of a cage, and front and rear sheet-metal to offer decent crumple zones.