Aero reverse trike project: Ninja 250 or Lifan 200 with electric assist/EV mode

[todayican]

Ok this aero stuff is looking more and more like rocket science, but sooo exciting!

Ok, I want to ask this in simple terms so I can get it through my thick head :-)

The shape below, is it the accepted standard as the best way to "foil" air and lead it to the rear of a vehicle with the least trailing turbulence (IE best cd)

(not counting laminar flow which is, lets call it impossible, for a road going car, even with faired EVERYTHING, theres going to be an imperfection of some sort.)

If someone says yes, my day will have been made, because on the vertical plane, the entire drawing (both sides) matches my chassis dimensions for my trike PERFECTLY :-D and I can make it work for the canopy profile as well.

So, is this the accepted answer for 'the best you can do" in aero?

[todayican]

Also, Bicycle Bob, love your posts! It seems you may be a good guy to ask this:

since this shape looks very "clark Y-ish" how big a deal might body lift be with a 900 to 1200lb (with riders) vehicle? Is mitigating body lift simply a matter of making sure the angle of attack is good and negative? say 10 degrees?

One other thing, the trike by design will have a 100% smooth body pan front to back, is it better to fair it well and let the body pan do its thing, or dam the air at the nose as much as possible? possibly with something like a rubber lower dam and go for say 2"?

[Hal]

I am working on a similar idea with my build: an all-composite tadpole built kind of along the lines of California Commuter but with more upright seating and handlebar steering. I bought a copy of Doug Malewicki's booklet on construction of the CC and may build one someday, but the reclining driving position seems a little difficult to get my 54 year old body in and out of...(I would recommend anyone interested in building a similar vehicle to get a copy - lots of useful information and ideas. I plan on using a 250 engine as well, but have been toying with the idea of a small diesel in parallel with a DC motor. It would run all electric to 25-30 mph, then engage a clutch to couple the diesel to the drivetrain and use the electric as torque assist for acceleration once cruising speed is reached. As an alternative, I have thought about leaving the motor and the diesel solidly connected, arrange a valve to vent the combustion chamber (so the engine doesn't drag on the motor) which would close at the 25-30 mph threshhold.
Build progress is slow since it is one of many projects, but I have some pieces cut of the carbon-fiber honeycomb I am using as a "frame" and a collection of fiberglass and carbon cloth, a gallon of epoxy and some other miscellaneous bits...

[todayican]

Cool Hal, you know I built something nearly identical! we should compare notes sometime, it was a 10hp diesel with a 84v ev drive.

[Frank Lee]

We operate in ground effect so airfoils are not where it's at.

There are many examples of "ultimate" low drag land vehicle forms that have been developed and refined with equipment we could only dream of having access to. My point is not to stifle, but to suggest that if the goal is max aero performance, it's probably easier, faster, and more likely to succeed, to follow in the footsteps that have been made. I'd look at solar cars, 1L (or other examples of optimized fe machines), research vehicles, HPVs, soap box derby cars, and/or winning shell economy ralley cars for inspiration- if not a blueprint to shamelessly copy.

[Frank Lee]

Originally Posted by Hal

I plan on using a 250 engine as well, but have been toying with the idea of a small diesel in parallel with a DC motor. It would run all electric to 25-30 mph, then engage a clutch to couple the diesel to the drivetrain and use the electric as torque assist for acceleration once cruising speed is reached. As an alternative, I have thought about leaving the motor and the diesel solidly connected, arrange a valve to vent the combustion chamber (so the engine doesn't drag on the motor) which would close at the 25-30 mph threshhold.

What?

[todayican]

Not above shameless copying :-)
I kinda have the 1 Liter as the base for my design, when I look at it and how sharply it tapers, I cant tell if its an optimum shape, or a consideration for having the 2 rear wheels back there.

Using the image above, im thinking I can bring the "tail" in more sharply being that im only running 1 wheel back there.

[todayican]

"We operate in ground effect so airfoils are not where it's at."

See thats the confusing part, seems like the right of passage with hypermiling is building the boat tail, which invariably makes the car look "wing ish" in cross section. No?

[oldenway]

Your project is right along the lines that I have considered doing. Please keep up the good work. I am anxiously following your progress.

old...

[todayican]

Man have I been going to town with that streamlining template and mpg calculator, I can tell you how appreciative I am to the team who put that together!

Ive been thinking, the name of the game of Aero is 1) Keep the frontal area down. 2) smooth is better 3) dont taper beyond the template specs and 4) pointy "terminations" of a shape are best.

All sound about right?

Ok, so the latest version of my drawing had me enclosing the tops of the wheels under a "hatch" that actuates when the wheel comes up in shock travel and having a fender that covers most of the wheel to form a pseudo enclosed wheel.

The thing is I have this niggling feeling that the thing just isnt "pretty" and thats hard to explain because I love aero things...

Ok, heres the idea, terminate the horizontal line where the people are horizonally and the vertical line enclosing the wheels and rear riders legs as the come around front rider with a vertical line (crude drawing attached)

Dont laugh but it calls to mind something from Star wars I think, from Naboo lol.