Designing an FE Car from the ground up.

[Mighty Mira]

This is a thread about designing an FE car from the ground up, starting with my thoughts.

[Mighty Mira]

Ok, some initial thoughts:
1) The vehicle must totally embrace the teardrop shape, with smooth fairings the whole way around. Wheel housings must also adhere to this. Worse comes to worse, the end can be truncated at some point, but only slightly.

2) Considering the realities of the situation, total vehicle cost must also be minimized. Few people are going to want to spend an extra $20k up front to save $1000 per year.

3) Considering the teardrop shape and vehicle stability, as it approaches this it approaches a tricycle in terms of appearance (i.e. as the two rear wheels come closer together, eventually it takes on the handling of a three wheeled car with two wheels at the front. This means that most of the weight must be at the front for stability concerns, and very likely, this is where the engine should go.

4) Where to put the luggage? As the rear of the car narrows, it becomes more logical to put the luggage in the center or front of the car, where most of the volume of the teardrop is, and an extra single seat at the back... OR an extendable boattail. Such a boattail would be also useful as a large crumple zone in the event of a rear end collision, remember Force * distance = Work.

5) The car should be full sized. Whether it should be as long as a suburban is debatable, but it should be looked at. The size I am going with for the highway version is 227 inches (same as the Excursion), and 57 inches high (same as the Camry).

[Mighty Mira]

Here is a very rough sketch of what the car would have to look like. In a front end collision, the driver would be in as good a shape as a collision in a tarago (a van where the driver is up front). Perhaps he could be seated further back if the windscreen wrapped around.

Note no rear-view mirrors - this is done via cameras. Also note I forgot to draw the rear wheels in one of the pictures.

Also, the highway model needs to be rotated a few degrees clockwise.

Miniaturize the highway model, make it a two seater (one in front of the other), and we have something like a single person commuting model.

[zpiloto]

Not trying to hijack the thread but are you trying to build the most FE car possible or or you trying to build a more FE car? I don't think that people would be ready to buy anything that is to far out there. I think that if you really wanted to make an impact you would need to do like Henry Ford and bulid a cheap car that gets 50+(like the smart car) that folks with out much money could buy. Something in the 6-10k price range. I think it was you that said most folks buy old cars because they cant afford new ones. So to help the overall situation build something inexpensive that gets good gas mileage so the masses are not driving around in 8-15 year old cars.

[Mighty Mira]

Something like that should get a Cd of 1.0 or less (hopefully less).

Using plastic panels on the outside, it should also be possible to make it quite light weight.

Which means that it would be quite possible to power it with a 500cc engine or less, which should be very cheap. Go with whatever fuel saving technology is cheap. Perhaps a large starter motor so that FAS can be easily integrated with the driving, and a tall gearbox.

Considering that 0.3 is good for a modern car as far as Cd works out, such a design would use probably less than a third of the power at speed.

Market it based on insulating yourself from fuel prices. Advertise it by capitalizing on other people's fear of price rises. Show what would happen if gas went to $10/gallon and interest rates went to 15% (i.e. to general people), and show what would happen to the hypothetical car driver.

Start off the advertisement by having a calm voiceover saying something like:

"I don't want to have to pick a right time to buy fuel. I work. I have a job I need to go to. I don't need to look good getting there, I just need to be there. If I want to look good, I buy some nice clothes. It doesn't improve my life to spend more money on a car, more money on fuel, more money on maintenance.

I like the idea that I can travel across the country for $20. I like the idea that I can spend more money on my family, on a home, on food, on clothes. On whatever I want to.

[Mighty Mira]

Another thing... what would necessarily make such a care expensive, provided that you used cheap trim, seats etc? The motor would be cheap as chips. Rear-view cameras aren't expensive probably less than $200 mass produced. See ebay for examples.

Can the boattail idea perhaps, although it shouldn't be that expensive, all that is required is four panels that slide out, following the contour of the floor, sides and roof. You already have rear-view cameras, so visibility shouldn't be that big of a deal.

I think this is one of those things that once there was something out there like it, it would take off, especially in times of high fuel prices and interest rates. With fuel prices taken to their logical endpoint, this is a logically designed car.

Of course, all buying decisions are emotional, not logical. So, first you need to create fear by painting a picture of what could happen. Then you need to show how buying this car is like buying insurance, it helps you sleep at night. It's one less thing to worry about. Lose your job and have to commute 100 miles in a day? No problem. Have to tighten your belt because your wife is staying home with the baby? No problem. It's one less thing to worry about.

[Mighty Mira]

Here is the Ford Probe V, a Cd of 0.137. Very interesting to read about.

[The Toecutter]

I think going after a normal-looking/performing car, and not a commuter vehicle would be a better idea.

My idea is this:

1) The vehicle must be a midsize car capable of seating five 200 pound, 6'5" adults
2) Must be able to run on renewable energy
3) Must obtain at least 50 mpg
4) Must obtain 0-60 mph acceleration of under 8 seconds
5) Must not appear radically different from the cars of today
6) Must cost under $30,000

A midsize car with the above seating capacity is easy and outlined above. This would basically be a vehicle at least the size of a Toyota Prius. Trimming out much dead weight from the interior could yield such a car with a weight around 2,900 pounds. Due to the car's size, frontal area will be about 23 square feet.

0-60 mph of 8 seconds or less? Must run on renewables? This calls for a diesel with at least 200 horsepower. Take a turbodiesel from a VW Jetta, add a performance chip and additional turbo boost.

50 mpg? The frontal area is set in stone, so the drag coefficient must be worked on. A .18 Cd sounds pretty reasonable given past accomplishments in the auto industry in regards to their concept vehicles or in the case of small companies, actual production cars. Google search the GM Precept(.16 Cd), Dodge Intrepid ESX-2(.20 Cd), Ford Probe V(.137 Cd), Alfa Romeo BAT7(.19 Cd), Tatra T77a(.21 Cd), among others. Basically, a Cd of .18 and 23 square foot frontal area yields a Cd*A of 4.14, about half that of a normal car. But aerodynamics only affects fuel economy at higher speeds. We already set the weight in stone at 2,900 pounds. So to get this efficiency? We're going to need LRR tires, synthetic transmission oil, low friction wheel bearings, and brakes that don't drag.

Appearance? Something along the lines of those cars I told you to google search.

GM Precept:


Dodge Intrepid ESX-2:


Those look like something people will buy. They look rather normal, if not sporty.

Cost? Well, we haven't used exotic composite materials, or exotic engine components. We haven't used a hybrid drive. Aerodynamics add little, if any additional cost to the manufacturing price of the car because it's simply a matter of how the car is shaped. Realistically, this could be a $20,000-25,000 car.

So overall, could these goals be met?

1) Midsize car? yes.
2) Capability to use renewable energy? Yes. It's a diesel and can be fit to run on B100.
3) At least 50 mpg? Yes. Diesel midsize cars in Europe without significant efficiency modifications like Mercedes' V8 diesels are already doing over 25 mpg combined. This car would probably get around 60-70 mpg with the outlined efficiency modifications and a more efficient diesel powerplant.
4) 0-60 mph acceleration under 8 seconds? Probably. 200 HP in a 2,900 pound car would theoretically allow 0-60 in the low 7-second region. As an added bonus, with the low drag design, top speed would be roughly 170 mph with the right gearing.
5) Normal appearance? Certainly achievable.
6) Under $30,000? Yes. No hybrid drive and no exotic components would make this a car that is certainly cheaper to produce than today's hybrids. It could probably sell for about the same as most entry level midsize cars, around $20,000-25,000.

[Mighty Mira]

Bat7

Tatra TT7A

[Mighty Mira]

I like the precept. It also does a good job of providing plenty of room in front for crumple zones in an accident. Not to mention the phenomenal drag coefficient.

The thing I love about these pictures is that they give so much in the way of ideas for our own vehicles. There isn't that much we can do about the exterior shape without incurring a lot of cost, but wheel covers, front skirts (Ford Probe V has a flexible membrane, I think I'd prefer something mechanical that would last longer), undertray, shaved door handles, rear view cameras, deflectors.