Aerodynamic Factors

[DrkAngel]

Either for speed or range, it is important to consider aerodynamics ... and road load.
I found some nice charts-graphs that really help!

Basic aerodynamic shapes - w/drag coefficients


Human Powered Vehicle Performance


Drag , via bicycle type - 22mph

Most impressive, to me, was that the "Upright Commuting Bike" requires almost exactly 2x the energy to maintain 22mph, as the "Racing Bike, Rider Crouched"!
("Air Drag", "Rolling Resistance" combined)

Watts required to maintain various speeds
(Note: These, tested, eMotorcycles are equipped with full front fairings!)


Pedal assist capability, Average & Athlete

[Kingfish]

Reminds me of Zzipper info:

anyone using a windshield? and
Zzipper '88 MTB Fairing is Here! and
The Aerodynamics of Human-powered Land Vehicles.

Swifty, like the wind - KF

[Kirk]

I have a Mueller Bros. XT fairing on my Catrike Expedition. Its small and not the best aero fairing out there, but its light, keeps my tootsies warm in the Winter and does give me a couple of mph for effort expended. These days they are made by Pat Franz's company TerraCycle in Portland, OR http://www.t-cycle.com/Merchant2/mercha ... y_Code=WWF

One of these days when I win the lottery, one their Cargo Monsters for touring is on my list of add ons. http://www.t-cycle.com/Merchant2/mercha ... _Code=cmon

[spinningmagnets]

Owls are relevant because although many shapes of birds can fly, the owl is known for being able to fly almost silently, which helps it catch mice at night. The silent nature of their flight indicates unusually low drag.

[DrkAngel]

One of my early graphs.
Demonstrates 450w and 675w output motors, at different gearings.
Test bike is an EZip Mountain Trailz


(16T lines, seem to be, nearing max capable speed.
Will test by upgrading 11T motor sprocket, from 9T, to 11T. = 81% torque 122% speed)

Will also test at 44.4V - should provide 30mph+, motor only.

[DrkAngel]

Yes! ... aerodynamics help ... 82mph - Human Powered "Bicycle".

[docnjoj]

I think that Myrtle the Turtle is using that additional rear platform on a Terratrike. It looks like a great idea to make trikes into real carriers,
otherDoc
edit: Yeah, Cargomonster.

[Kingfish]

Yes! ... aerodynamics help ... 82mph.

Awesome! Thanks for sharing

With the racer, I wondered if he polished the surface of his shell, or if he left the micrograin intact. There’s a school of thought that follows the physics of golf balls wherein a uniformly imperfect surface creates a boundary layer condition that promotes slipstream rather than developing into drag.

The farings on my bike and trailer made a huge difference, both in slicing through the headwind, with crosswinds, and with passing trucks. The biggest single gain came from my front faring where I picked up 2-3 mph. The trailer had a good teardrop shape to it, and at high-speed provided exactly the self-correcting drag I was hoping for.

Like the wind, KF

[DrkAngel]

Yes! ... aerodynamics help ... 82mph.

Awesome! Thanks for sharing

With the racer, I wondered if he polished the surface of his shell, or if he left the micrograin intact. There’s a school of thought that follows the physics of golf balls wherein a uniformly imperfect surface creates a boundary layer condition that promotes slipstream rather than developing into drag.

Like the wind, KF

Nice question ...
Hmmm!
Need:
a small wind tunnel
variety of "surfaces", smooth plastic to, ultrafine emery cloth, through various grits of sandpaper, then to fine rug, right to shag carpet 8.5" x 11" for ease of availability.
curve each into an "aero" shape

aero.JPG (2.22 KiB) Viewed 670 times

Test in wind tunnel

Should give interesting results!
Sorry ... all out of wind tunnels ... :<(

Could be a great science fair project, or similar?

[alex12342011]

Take a look at this diagram I found. Golf balls owe most of their drag to that vacuum caused from the flow separation. Flow separation on the streamlined body isn't nearly as large, and most of the drag is caused by skin friction. A rough or dimpled surface causes turbulent flow to reduce the large pressure drag on the ball.

[DrkAngel]

237MPG @ ~55mph

Great potential as an eMotorcycle!
Except ... possibly, for crosswinds?

[migueralliart]

237MPG @ ~55mph

Great potential as an eMotorcycle!
Except ... possibly, for crosswinds?

Does this mean I need aerobars for my commute of ~8 miles which is indeed a straight road with an awesome wide bike lane?

Perhaps.... time to justify another ebike accessory for the sake of proving a point.

[CrazyJerry]

"Crosswinds"
And it would be nice if those were steady but they can come intermittently from between houses, edges of hayfields, treelines, etc. Hold on and throttle it!
~CrazyJerry

[MadRhino]

237MPG @ ~55mph

Great potential as an eMotorcycle!
Except ... possibly, for crosswinds?

This older Vetter designed fairing, shown in the page you linked to, should be easy to adapt to my little road racer. Making it with CF would make for little weight addition. I must find the spare time to give it a try.