Designing and Building my own High MPG Car

[Frank Lee]

Seems everything you propose is going in the right direction!

[Patrick]

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.

You might want to consider a tandem 2-seater. It won't require much more space or materials, but will greatly enhance the usability of the car and can even enhance the aerodynamics by increasing the fineness ratio.

[Fat Charlie]

A two seater would make it more useful. Seating them fore and aft would keep the frontal area down and minimize design changes. For not a lot of added weight you can bring a passenger or carry an extra few grocery bags.

[jkv357]

Don't know if you've seen this info about a 250 Ninja powered 3-wheeler -

Freedom Machine - Fuel Economy -Chap 37

Lots of interesting stuff on Vetter's site, but it's buried in scattered links and is a bit hard to find.


Jay

[euromodder]

Originally Posted by deathtrain

good luck but think a three wheel would result in better FE/aero.

The extra drag is a small price to pay for the greatly improved stability needed in an everyday vehicle.
It can be minimized by carefully selecting narrower, LRR tyres.

If you start removing wheels just to reduce drag & weight, there's no real reason to stop at 3, hence the E-Tracer :

[euromodder]

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.

A single seater severely limits the usefulness of any vehicle, meaning most people will also need another vehicle, requiring yet more resources.
While many in the US may have a mini fleet of vehicles to choose from, this isn't the case elsewhere on the planet.

Of course, I am planning on have storage for about 4 bags of groceries.

If you plan for the Vetter-conditions, that will be what your vehicle is mostly useful for. Sure Craig can carry his 4 bags of groceries, but he can't take his wife, a friend or grandkids along ... not even one of them.

In an environment where people might go looking for more economical / ecological solutions, a single seater must be highly efficient, when it doesn't want to look silly when compared to the very low tech option of people carpooling.


The dimensions needed to seat two in tandem can even work to your advantage, length is beneficial when you start streamlining.

The modest extra weight won't matter too much on a vehicle designed as a long range commuter.


Fairing in the volume between the wheels rather than putting them in pods, will increase frontal area, but it reduces interference drag of multiple streamlined bodies in close proximity.
It would however greatly improve the useful volume to carry anything while adding crumple zones.
Calculate the wet area and total CdA, and see if a design with the voids filled in has significantly more drag.


The streamlined struts carrying the wheels may look neat on paper, but technically they're a bit of a handfull given that you'll need to incorporate steering, suspension and strength.

[GoGogebic]

Thanks for all the comments!

I'm definitely building this car with the thought that you would need another car, but it would be cheap enough (4-7 thousand dollars) that that shouldn't be a problem.

Here's my thinking. Ever since my wife got her honda fit I haven't had one person in the passenger seat of my car. I drive 60 miles each way to work, and no ones car pooling with me. It a fair guess to say for me that no ones ever going to use the passenger seat.

From your guys comments it seems like you think people would use the back seat. From what I've heard about tandem cars, people feel embarrassed to ride in the back. Its kind of degrading in some people's mind. I'm no Don Juan, but if you try to pick up a date in a tandem car the girl probably is not coming back for seconds. So my thought is get yourself a old pickup or a muscle car or something fun to ride close to home and then drive the singleseater to work.

Also I think there is a misconception about how much adding the extra seat would cost. I'm in the precision metal fabrication business and I estimate the added cost of the second seat is at least 25% of the vehicle cost. Adding length would make parts that require odd size material and would require bigger machines to produce, etc.

As far as the suspension goes think sprint car, but enclosed. Not really that complex.

I hope all you take my comments in the right tone. I really appreciate your comments and enjoy the criticism.

Thanks
GoGogebic

[deathtrain]

not a bad idea about the sprint car idea but my concern would be with the tires so far out and not tucked in. you would have an open wheel effect.

"someone not paying attentin and clips the front wheel thus ripping it off and sending you into the wall of death...."

I am all for the single seat idea I just cant get past the above issue.

[GoGogebic]

Deathtrain,

I have spent sometime thinking about your concern. I have definitely thought of the problem of openwheels jumping up other peoples wheels(this is one of the reasons why I enclosed the wheels in fairing). I haven't seen much of cars actually clipping off peoples wheels, but I like the scrutiny. Sprint cars have nerf bars. I will consider adding them to this car to eliminate the concern you have. One of my thoughts is if some one hits you hard enough to rip off your wheel then they would probably end up sending a fendered car in to the wall as well.

[Fat Charlie]

Originally Posted by deathtrain

not a bad idea about the sprint car idea but my concern would be with the tires so far out and not tucked in. you would have an open wheel effect.

"someone not paying attentin and clips the front wheel thus ripping it off and sending you into the wall of death...."

I am all for the single seat idea I just cant get past the above issue.

Nerf bars may limit mechanical damage, but they're not going to save lives. If you're driving something efficient (small), you're always going to be at risk from comatose FSP drivers.

Focusing on one particular type of damage is just quibbling at that point: if a 2800 pound Elantra gets edged out by a 6300 pound Suburban, nobody's going to credit the fenders with saving lives. No matter what you do you can't defend against mass, so focus on what you can control: a strong body (or at least safety cage) and a good seat. Some off the shelf racing seat, probably.