Aerodynamic Factors

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DrkAngel
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Aerodynamic Factors

Post by DrkAngel » Feb 12, 2012 10:00 am

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
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Human Powered Vehicle Performance
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Drag , via bicycle type - 22mph
Image
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!)
Image

Pedal assist capability, Average & Athlete
Image
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Re: Aerodynamic Factors

Post by Kingfish » Feb 12, 2012 12:38 pm

* My 2WD Garden Wall
* Kinaye MotorSports
* Primary ride: 2WD Disc 9C 2806-equiv / Dual Lyen 12FET / 20S7P LiPo.
* Epics: Going to California: 2011 8)
* 50-mph, 101, 10k-Club. 12,527 miles-to-date, 7037 as 2WD.

It is by caffeine alone I set my mind in motion.
It is by the beans of Java that thoughts acquire speed.
The hands acquire shakes, the shakes become a warning.
It is by caffeine alone I set my mind in motion.

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Kirk
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Re: Aerodynamic Factors

Post by Kirk » Feb 12, 2012 6:56 pm

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
Stable:
05 Catrike Road (Yellow), 20" 48V 1000W GM hub motor,12s24Ah Lipo batt.
12 Catrike Expedition (Candy Purple), 18s32Ah Lipo batt. Lyen 18 FET low RDS controller, C'Lyte HS3540 hub motor, CA-SA, Mueller Bros. Windwrap XT fairing, Terra Cycle Cargo Monster extension. Still evolving, should be interesting by next Spring.
2011 Roll Over America tour, 50 Velomobiles, 5000 Km, 24 days, Portland, OR-Washington DC, July 28th-August 24th 2011, damn I was tired after that.

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Re: Aerodynamic Factors

Post by spinningmagnets » Feb 12, 2012 10:43 pm

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.

Image
Last edited by spinningmagnets on Feb 26, 2012 6:40 pm, edited 1 time in total.

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DrkAngel
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Re: Aerodynamic Factors

Post by DrkAngel » Feb 14, 2012 12:58 pm

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

Image
(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.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

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DrkAngel
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Re: Aerodynamic Factors

Post by DrkAngel » Feb 26, 2012 9:23 am

Last edited by DrkAngel on Feb 29, 2012 9:35 am, edited 1 time in total.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

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docnjoj
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Re: Aerodynamic Factors

Post by docnjoj » Feb 26, 2012 12:23 pm

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.
E-bike stable at our house

Steintrike Mad Max full suspension trike rear Cute 100H going on: Whoops, Cute wheel broke but I fixed it.
Sun USX delta trike EbikeKit small geared front wheel sort of front suspension for wife

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Re: Aerodynamic Factors

Post by Kingfish » Feb 26, 2012 1:32 pm

Awesome! Thanks for sharing 8)

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
* My 2WD Garden Wall
* Kinaye MotorSports
* Primary ride: 2WD Disc 9C 2806-equiv / Dual Lyen 12FET / 20S7P LiPo.
* Epics: Going to California: 2011 8)
* 50-mph, 101, 10k-Club. 12,527 miles-to-date, 7037 as 2WD.

It is by caffeine alone I set my mind in motion.
It is by the beans of Java that thoughts acquire speed.
The hands acquire shakes, the shakes become a warning.
It is by caffeine alone I set my mind in motion.

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DrkAngel
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Re: Aerodynamic Factors

Post by DrkAngel » Feb 26, 2012 8:05 pm

Kingfish wrote:
Awesome! Thanks for sharing 8)

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 onto an "aero" shape
aero.JPG
aero.JPG (2.22 KiB) Viewed 2378 times
Test in wind tunnel

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

Could be a great science fair project, or similar?
Last edited by DrkAngel on Dec 28, 2017 6:53 am, edited 1 time in total.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

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alex12342011
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Re: Aerodynamic Factors

Post by alex12342011 » Feb 27, 2012 12:31 am

Image
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.

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Re: Aerodynamic Factors

Post by DrkAngel » Feb 27, 2012 1:22 am

237MPG @ ~55mph

Great potential as an eMotorcycle!
Except ... possibly, for crosswinds?
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - November 2015

EBike Toolbox - Bargains! $

Endless Sphere Wiki

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Re: Aerodynamic Factors

Post by migueralliart » Feb 27, 2012 5:55 pm

DrkAngel wrote: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.

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Re: Aerodynamic Factors

Post by CrazyJerry » Feb 27, 2012 10:42 pm

"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
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Re: Aerodynamic Factors

Post by MadRhino » Feb 28, 2012 9:31 am

DrkAngel wrote: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.

Image
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