Some Scratch Build Ideas
 

Like many folks here, I keep thinking of "rolling my own.";)

More specifically, I keep thinking of building a "car" from scratch which would optomize aerodynamic and propulsion ideas.

Here are some design drivers which seem personally relevant:
1. Probably most important is that I live in VA and they are tough on home builts, unless it is classed as a motorcycle. So I'm thinking of starting with a motorcycle engine and rear suspension, but I want to wind up with weatherproof tandem seating for two. Part of that inspiration was this:

214 mpg with DIY aerodynamic fairings on a Honda 125cc motorbike

2. If it is to be tandem for two then it is probably going to be taller than wide. Because of this, I'm considering outriged front wheels for a so called tadpole design. This architecture seems ideal for a good "template approach in plan view, as the above ref motorcycle.

3. How to do the front suspension? There is the choice of streamlined struts, perhaps with inboard shocks and springs(a la Formula Ford) and streamlined steerable fairings for the two front wheels, or,

4. A complete faring in of the front suspension, body all the way out past the front wheels (a la VW L1).

Approach in 3 has the advantage of lower A in the CdA mix, but the Cd will be a bit higher.

Approach in 4 has the advantage of a lower Cd, but the A will be a bit larger.

I'm leaning toward approach 3 since I can probably find a relatively modern Formula Ford front, from a wreck, as a starting point.

I would love to have some comment on this trade-off. Perhaps others have though some of this through. I think the less important front can be relatively close to template and certainly the rear plan view can hold template for some considerable distance before truncation.

Any comments or suggestions welcome:)

Sylph
 

Jim have you seen Llewelyn's(sp?) Sylph?

did u look at my "motorcycle"??? mine is more of an all weather car kind of thing, and less of a true "bike", but it is recognized as a motorcycle as it has 3 wheels.

No I have not seen that. I was unable turn up anything on it by searching here and on google. Do you have any links?

Think I may have seen that, but I'll have to do some searching later :)

A search of "Llewellyn Sylph" turns up some music related results -- any other keywords that would help?

Jim, have you studied Ken Fry's Zing! which takes the tandem/enclosed fixed front wheel fenders path? Another option (depending on your local laws) is the Duo Quest by Allert Jacobs; which is a side by side vehicle with a pair of closely spaced rear wheels, and widely spaced front wheels. This may or may not qualify as a trike. An example of a standard trike with side-by-side seating is the TWIKE. I think the way it avoids the stability issues is keeping the speeds below highway speeds.

The main challenge of a trike is Cg. The location of the engine and the location of the people are the key things that determine the Cg. The geometry of the seating matter a lot to Cg. The height of the Cg matters a lot -- many tandem trikes lean in turns. Side by side trikes have very wide track on the pair of wheels, or longer wheelbase, or a closely spaced pair of wheels substituted for the single wheel (or a very wide single wheel).

Leeuwen Sylph
 

Did a bit of searching because I'm too curious to wait - two photos of a model is all I've found so far. Having the right name helps a little :D
As I'm a lurker hopefully someone can parse the links to make it easier for others


Matt Van Leeuwen "Sylph"

flickr.com/photos/39375104@N08/6941277240/

From page 6
calteches.library.caltech.edu/528/2/Bettes.pdf [1982]

Thanks!

http://farm8.staticflickr.com/7106/6...b92f7f01_z.jpg

Leeuwen | Flickr - Photo Sharing!

calteches.library.caltech.edu/528/2/Bettes.pdf

The Matt Van Leeuwen "Sylph" looks like it requires a very clever front suspension, similar to the Edison2 VLC. By the way, Ron Mathis who is the lead engineer for Edison2 just got the patent for their VLC suspension.

Yeah, I turned up all that musical stuff too. Maybe Phil will be a bit more specific.

I thank you for your thoughts. I am leaning toward the tandem seating idea because it keeps the frontal area small. The VW L1 did the same thing. But, your thoughts on cg height are certainly serious concerns. I don't think a car that leans into the turns like a bike is going to be an attractive approach, for lots of reasons.

I love the shape. Looks like it would work great for a motorcycle based approach with tandem seating.One would have to handle the canopy size and rear visibility issues very carefully. Too much greenhouse and you get a sauna. The cg issue would need careful attention. A motocycle engine is fairly low, but passengers would be a cg challenge, maybe one high and one low?

I think I know how to do the front suspension. Ever heard of the Morgan sliding pillar?

I have not heard of the Morgan sliding pillar...

But Wikipedia has an entry: http://en.wikipedia.org/wiki/Sliding_pillar_suspension