Aerodynamic efficiency: Narrow body, wheels outboard vs wider body enclosing

[Frank Lee]

Originally Posted by Xist

I bet the sports car had better braking ability...

Looks like he didn't...

[ScotD]

Originally Posted by Xist

I second this. Make something you are proud of, but make something. Too many people talk. Too few people actually do anything.

Currently I'm waiting on the Washington State bureaucracy to decide what will be necessary for them to license a trike (legally motorcycle here) with home built or modified frame and front suspension. They're working on it . . .

After the feedback to this thread I'm pretty sure I'll do the narrow body with front wheels outboard.

I'm also not yet certain about the donor machine (almost certainly motorcycle in the 125 to 250cc range) nor about the front suspension.

The front end that looks best at this point is that designed for and used for the California Commuter, 1980. There are some issues with that. It's light weight, simple, and relatively easy to build, but uses very old Honda cycle/scooter wheels with drum brakes. Unfortunately I don't see how to adapt it to more modern wheels with disc brakes . . . I'd love to find a very simple front end design using readily available and reasonable cost more modern parts that is equally light-weight and otherwise suitable. Perhaps that will be a new thread somewhere on the ecomodder forums.

[aerohead]

Originally Posted by ScotD

Currently I'm waiting on the Washington State bureaucracy to decide what will be necessary for them to license a trike (legally motorcycle here) with home built or modified frame and front suspension. They're working on it . . .

After the feedback to this thread I'm pretty sure I'll do the narrow body with front wheels outboard.

I'm also not yet certain about the donor machine (almost certainly motorcycle in the 125 to 250cc range) nor about the front suspension.

The front end that looks best at this point is that designed for and used for the California Commuter, 1980. There are some issues with that. It's light weight, simple, and relatively easy to build, but uses very old Honda cycle/scooter wheels with drum brakes. Unfortunately I don't see how to adapt it to more modern wheels with disc brakes . . . I'd love to find a very simple front end design using readily available and reasonable cost more modern parts that is equally light-weight and otherwise suitable. Perhaps that will be a new thread somewhere on the ecomodder forums.

I GOOGLED 'street legal 3 wheelers for sale' and a bunch of info came up.
You might be able to score something with a valid VIN number,which satis
fies some of your engineering requirements,then modify it to your taste,knowing that most of the mechanicals are pre-approved by Caesar.
Just a thought.

[NeilBlanchard]

Another complication of outboard wheels apparently, is in crosswinds, there is more drag than with a single unified body.

[3-Wheeler]

Originally Posted by ScotD

......After the feedback to this thread I'm pretty sure I'll do the narrow body with front wheels outboard.....

The narrow body also has the advantage of being shorter for the same Cd.

As Phil mentioned earlier, the Cd of a full body may be better, however having shorter bodywork has advantages too.

Edison2 spent a lot of time determining which body configuration to go with, also decided on outboard wheels with skirts.

Jim.

[NickelB NL]

I have an idea. Look at this MEV Eco-Exo | Exomotive – US Dealer of Exocars & Kit Carshttp://it is based on a suzuki burgman. Solid frame en simpel front susspention. And on that frame it would be easy to make an aero body for it. Also the wheel fenders would be easy to make on thet frame

[aerohead]

Here's a couple of images that Neil posted for us of "Sylph" in the Cal Tech tunnel,from Jime57's thread: Some Scratch Build Ideas
Sorry,I couldn't link it.They're on page one of that thread.
The way the front wheels were done might be of interest.
Let's try this,
http://farm8.staticflickr.com/7106/6...b92f7f01_z.jpg

[freebeard]

The narrow body also has the advantage of being shorter for the same Cd.

I'd go with '...for the same fineness ratio.'

I know—pedantic.

Another complication of outboard wheels apparently, is in crosswinds, there is more drag than with a single unified body.

Does a solid wheel act like a rudder compared to a wire wheel? Does the wire wheel have lower crosswind drag? Just asking questions.

If the wheels are ahead of the stagnation point of the main body, the 'biplane' interference is halved; if they are behind the stagnation point one or the other is shielded from the crosswind by the main body.

I should do an illustration of the front fender that been rattling around in my head. It could apply to a lot of different situations. If I say 'baloney-cut Indian front fender' does that paint a picture?

[oldtamiyaphile]

Originally Posted by freebeard

Does a solid wheel act like a rudder compared to a wire wheel? Does the wire wheel have lower crosswind drag? Just asking questions.

In cycling, disk wheels are much more suceptible to cross wind forces. I believe this is the main reason they're banned from group events. You'll generally only find disc wheels on the rear of bikes for cross wind stability reasons. They certainly could 'steer' a bike, but that's mainly down the the steering geometry, which wouldn't be much of an issue on a car.

[freebeard]

They certainly could 'steer' a bike, but that's mainly down the the steering geometry, which wouldn't be much of an issue on a car.

Because cars have camber and toe-in where bikes don't?