Aerodynamics

General Discussion about electric bicycles.
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Re: Aerodynamics

Post by ecycler » Aug 26 2014 1:35pm

First time I have seen someone put those two together. That's a pretty good demonstration of kite and bike control, but kind of a ballsy play without his kite leash hooked up! It does not appear to be clipped to the 5th line. I guess that was back in 2007 when everyone was freaking pumped about the new tech and showing off how much more depower their new delta kites had over the c-kites! haha It is even crazier to think that humans didn't figure out how to properly design traction kites and their bridals until less than 10 years ago for that big jump in safety!
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Re: Aerodynamics

Post by Tommy L » Aug 26 2014 5:09pm

tahustvedt wrote:Well. It would be possible to attach vertical rigid construction high aspect ratio sails to the front of a tadpole trike for example. A simple mechanism to direct it efficiently relative to the wind would give some fwd assistance in most directions as long as there is wind. Nothing but drag if there is not enough wind though.
I've been an avid sailor and sailboat owner for many years........
What I can tell you is that........ In a "No Wind" situation under motor only, my sailboat would cruise at 5.5 knots and in the same "No Wind" condition with
the main sail up on a close haul..... 7 knots. Things that make you go, hmmmmmm ;) The Vacuum that pulls :)

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Re: Aerodynamics

Post by John in CR » Aug 26 2014 5:46pm

You have a different definition of no wind than I do. I want a boat I can go to China in and go ebike parts shopping in person, so I'm not talking about about sailing in a puddle...sorry, I mean lake. FWIW, any electric boat I build will be able to do hull speed on solar alone

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Re: Aerodynamics

Post by swbluto » Aug 30 2014 8:43pm

It's interesting to see that the 1988-1991 Honda CRX HF cars have an effective drag area (The closest thing to the 'aerodynamicness' of an object) pretty much equal to a normal mountain biker.

http://ecomodder.com/wiki/index.php/Veh ... _Drag_List

(Note: The Honda CRX HF car is the most aerodynamic car on the list behind the First Gen Honda insight. The only other car I've found with better aero is a 1990 Corvette, which I haven't had much luck in finding for sale online, lol.)

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Re: Aerodynamics

Post by LockH » Aug 31 2014 1:48pm

Hehe... a thread within a thread. Call it "Dynamics of Aero" (used and minimized/optimized as energy stored to power vehicle etc. "House currents" on a boat).

Dunno `bout how MUCH cargo (weight, space vs towing), but I would def. go "Polynesian-style" maybe (modern plastic, metal, etc. Yah. Not a REAL "woodie", sadly. Prettiest catamaran seen so far w/wood layers laminated outer foam "sandwich" construction.)

Like ebikes, lead-free ("keel"-less sailing) once "too foreign" for NA etc. tastes.

Hehe... "puddle". I have "sailed the salt" many times (plus rivers, lakes, parking lots). The boundary `twixt two fluids. Lakes etc. def. maybe more "lumpy" at times. (Caused by WINDS of course. More near shores, lunar pull tends to make stuff "run around" - Jello in a bowl, changing water flows... I have seen river water rushing "up hill" once/twice per day. (Watt a landlubber terms "downhill". See also *gravity*.)

Solar alone? Nice. Though hull speed at vanishing small hours of wattEVer daylight hours available each rotation. One nice thing about winds (wind energy)? It "sees over horizons". Bends (and can be "bent") around... stuff.
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Re: Aerodynamics

Post by LockH » Aug 31 2014 11:09pm

Speaking of aero, June 25, 2012, "Three Wheeled Green Vehicles":
http://cargatuso.blogspot.ca/2011/01/th ... icles.html

eg:
green-cars-ventureone.jpg
green-cars-ventureone.jpg (22.04 KiB) Viewed 2476 times
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So. "Aero" enough for ya?
Last edited by LockH on Sep 04 2014 8:48am, edited 1 time in total.
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Re: Aerodynamics

Post by LockH » Sep 03 2014 3:42am

"47% less aerodynamic impact"


Seen re latest antique, pedal-only two-wheeled ride design "thinking".
http://road.cc/content/news/129081-xxx- ... nago-giant
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Re: Aerodynamics

Post by LockH » Sep 04 2014 8:41am

Hehe... speaking of "aerodynamics"...












(Sorry `bout that. Just reminded re this thread topic... ermmm sub-topic topic.)
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Re: Aerodynamics

Post by Tommy L » Sep 04 2014 2:16pm

LockH wrote:Speaking of aero, June 25, 2012, "Three Wheeled Green Vehicles":
http://cargatuso.blogspot.ca/2011/01/th ... icles.html

eg:
green-cars-ventureone.jpg
One kick butt Bettery-Electric recumbent three-wheeler (guest traveller seating also).

So. "Aero" enough for ya?

Probably better Aero Backwards! ;) :P
http://www.rawvelocity.com

- 4th Hoolagan FS Mtn 9C-2810 with 128v nom 9.2ah A123 40S40P(1.2Kw) - Lyen 18Fet 4115 - 77.8kph :)
http://endless-sphere.com/forums/viewto ... =4&t=39480

- 3rd Catrike 700 Bionx PL350 Velo build
http://www.youtube.com/watch?v=rYdnkaAhVtI

- 2nd 150lbs Pusher Trailer
http://www.youtube.com/watch?v=Q1qTc4sjORY

- 1st Sears NS mtn bike - Rigid 10a drill 800rpm - 2 12v AGM - 1000 watt inverter - 600w dimmer for throttle, wicked torque!

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Re: Aerodynamics

Post by cycborg » Sep 05 2014 9:00am

You may have heard that electric+aero cleaned up at this year's Vetter Challenge - about 100 Wh/mi over 200 mi at 60-80 mph including some mountain roads. For reference, EPA rates the Leaf at 300 Wh/mi.

But now compare to an unfaired, upright-seated ebike, with typical numbers of 20 Wh/mi at 20-25 mph. That's about 1/3 of the speed, and 1/5 the energy requirement of the Vetter champ. Really helps you appreciate the linear relationship of power vs. CdA compared to the cubic relationship of power vs. speed.

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Re: Aerodynamics

Post by Jonathan in Hiram » Sep 06 2014 3:07am

What's most interesting to me is that the winner is not narrow and sleek but kind of bulbous and chunky, more like a grouper or a sperm whale than a barracuda.

Image

Image

With that tail you'd think he gets blown all over the road, or is it that his bike is just heavy enough to not be bothered by all that.

Image

I think the bulbous nose blows a "bubble" of relatively calm air in which the rider sits, the wedge on the rear then brings the bubble to a close with minimal vortex formation, riding a motorcycle with a Vetter fairing on it I always noticed how the air would come at me from behind.

Oh, and I just realized the top of his fairing including the windshield and the portion in front of the hands rotates with the handlebars, he got that design detail from Vetter's "Alcan" fairing.
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Re: Aerodynamics

Post by veloman » Sep 06 2014 10:16am

Spend some time reading on Vetter's website. Round in the front, pointed at the rear - that's the moto. That's aerodynamics.

Terry's bike is 25" wide at the widest point. Yes it's a bit 'fat', but he needs all that space to carry the 21kwh and 10 chargers. Look at the Hayes diesel bike - it's much narrower. I'm willing to bet that the Hayes bike uses less power to go the same speed. I'm going to build mine more like that, about 16-18" wide (my shoulders being the widest).

As for the tail - the bikes weight of 1000lbs helps with stability. Terry has said how he has no problem with cross winds at 80mph.

I'm been riding my moto conversion at 50-55mph a few times and don't notice any instability from crosswinds, and my bike weighs only 360lbs (with me on it). No fairings though. My ebike which is 80lbs less and has a front fairing, gets pushed around a lot more in the crosswind. Still not a problem, you just lean into it.
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Re: Aerodynamics

Post by gogo » Sep 06 2014 10:47am

I like the tail. It might give motorists the idea that they should make damn sure they don't hit you from behind. It also provides a possibility for an energy absorption device, or at least redirection. Instead of getting bounced forward in a rear impact collision, maybe the tail angle would cause the car to pop you up and the tail into their face.
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Re: Aerodynamics

Post by Modbikemax » Sep 06 2014 7:23pm

Check out Randy Grubb's Decopods, they are a lot cooler looking than the Vetter designs.

http://www.randygrubb.com/decopod-bi-pod/

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Re: Aerodynamics

Post by doctorGONZO » Sep 07 2014 1:47am

Jonathan in Hiram wrote:What's most interesting to me is that the winner is not narrow and sleek but kind of bulbous and chunky, more like a grouper or a sperm whale than a barracuda.

Image

Image

With that tail you'd think he gets blown all over the road, or is it that his bike is just heavy enough to not be bothered by all that.

Image

I think the bulbous nose blows a "bubble" of relatively calm air in which the rider sits, the wedge on the rear then brings the bubble to a close with minimal vortex formation, riding a motorcycle with a Vetter fairing on it I always noticed how the air would come at me from behind.

Oh, and I just realized the top of his fairing including the windshield and the portion in front of the hands rotates with the handlebars, he got that design detail from Vetter's "Alcan" fairing.
When someone first ever starts seriously studying aerodynamics they often are surprised to discover that the shape with least drag, at speeds less than 1 or 2 hundred MPH is the bulbous grotesque bubble shape, not the sharp pointed blade shaped nose.

As a motosickle rider many years ago today, I too noticed that the wind whipped around my windshield and blew past my head FORWARD, waving my beautiful long Elvis-like hair FORWARD whipping it into my eyes. My windshield was the small "sports" windshield germane to the old day 1950s and 1960s. Used a few times and abandoned, not worth the trouble.

Helmet? To control hair placement and movement?! You gotta be kidding. Not cool and too expensive.
Last edited by doctorGONZO on Sep 07 2014 2:01am, edited 1 time in total.

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Re: Aerodynamics

Post by doctorGONZO » Sep 07 2014 1:53am

veloman wrote:Spend some time reading on Vetter's website. Round in the front, pointed at the rear - that's the moto. That's aerodynamics.

Terry's bike is 25" wide at the widest point. Yes it's a bit 'fat', but he needs all that space to carry the 21kwh and 10 chargers. Look at the Hayes diesel bike - it's much narrower. I'm willing to bet that the Hayes bike uses less power to go the same speed. I'm going to build mine more like that, about 16-18" wide (my shoulders being the widest).

As for the tail - the bikes weight of 1000lbs helps with stability. Terry has said how he has no problem with cross winds at 80mph.

I'm been riding my moto conversion at 50-55mph a few times and don't notice any instability from crosswinds, and my bike weighs only 360lbs (with me on it). No fairings though. My ebike which is 80lbs less and has a front fairing, gets pushed around a lot more in the crosswind. Still not a problem, you just lean into it.
For any specific speed, the WIDTH giving the least drag is a specific width. Any larger or smaller width will give you MORE DRAG.

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Re: Aerodynamics

Post by Chalo » Sep 07 2014 11:12am

doctorGONZO wrote:For any specific speed, the WIDTH giving the least drag is a specific width. Any larger or smaller width will give you MORE DRAG.
Um, no. I think you're either misinterpreting or oversimplifying the fact that the ideal airfoil shape has a different chord (length:thickness ratio) for any specific speed. That's very different than what you said, not least because nobody here is willing and able to use an ideal airfoil as a fairing shape.
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Re: Aerodynamics

Post by LockH » Sep 07 2014 11:24am

Chalo wrote:... ideal airfoil as a fairing shape.
Please enlighten Oh Wise One?
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Re: Aerodynamics

Post by doctorGONZO » Sep 08 2014 2:25am

Chalo wrote:
doctorGONZO wrote:For any specific speed, the WIDTH giving the least drag is a specific width. Any larger or smaller width will give you MORE DRAG.
Um, no. I think you're either misinterpreting or oversimplifying the fact that the ideal airfoil shape has a different chord (length:thickness ratio) for any specific speed. That's very different than what you said, not least because nobody here is willing and able to use an ideal airfoil as a fairing shape.

Well, errrr, then there now, I'm having to guess at what you are trying to say....Maybe you are trying to say ideal streamline?

To remind you of what I said; I wrote about the width that will give minimal drag: I did not write about nobody round here being willing and able, or, being unwilling and unable, to use an ideal airfoil.

And I was writing about my having given admiring glances at the bike with the beautiful big bulbous LOW DRAG :P streamline fairing.

It is true that I simplified my post. I have been acutely aware of the L/R (or, Length to Width) "rule" of streamlining since reading about it in an aerodynamics textbook in the early 50s.

You are obviously still sore about my exposing your ignorance about the definition of power two years ago, or whenever. Please do not troll me just to try to get even by raising arguments about the meaning of the word is. I know what the meaning of the word is is. The meaning of the word is is is.

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Re: Aerodynamics

Post by gogo » Sep 08 2014 7:54am

doctorGONZO wrote:For any specific speed, the WIDTH giving the least drag is a specific width. Any larger or smaller width will give you MORE DRAG.

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I can't buy into that statement, either. There are too many variables left out for it to be meaningful.
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Re: Aerodynamics

Post by mclark999 » Sep 08 2014 8:11am

I'm looking for a front fairing for my bike that will just help keep winter chill off as much of my body as possible. What sources are available for a diamond frame bike?
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Re: Aerodynamics

Post by Jonathan in Hiram » Sep 08 2014 1:41pm

doctorGONZO wrote: When someone first ever starts seriously studying aerodynamics they often are surprised to discover that the shape with least drag, at speeds less than 1 or 2 hundred MPH is the bulbous grotesque bubble shape, not the sharp pointed blade shaped nose.

As a motosickle rider many years ago today, I too noticed that the wind whipped around my windshield and blew past my head FORWARD, waving my beautiful long Elvis-like hair FORWARD whipping it into my eyes. My windshield was the small "sports" windshield germane to the old day 1950s and 1960s. Used a few times and abandoned, not worth the trouble.

Helmet? To control hair placement and movement?! You gotta be kidding. Not cool and too expensive.
While I'm not aerodynamic genius I've designed and built several of my own RC planes that flew pretty much the way I wanted them to back in the day. I didn't say I was surprised at the shape of the Vetter contest winner I said it was interesting.

Ever seen the Mercedes "boxfish" car? Designed with some of the same flow principles as the boxfish exhibits.

Image

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Re: Aerodynamics

Post by speedmd » Sep 08 2014 2:57pm

You want slippery aero. Follow nature, it has it figured out for you already.
Image

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Re: Aerodynamics

Post by cycborg » Sep 08 2014 3:36pm

speedmd wrote:You want slippery aero. Follow nature, it has it figured out for you already.
Not sure what that is, or where it occurs in nature.

Apropos of nothing, here's what raindrops look like:
Image

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Re: Aerodynamics

Post by Jonathan in Hiram » Sep 08 2014 4:20pm

mclark999 wrote:I'm looking for a front fairing for my bike that will just help keep winter chill off as much of my body as possible. What sources are available for a diamond frame bike?
This looks promising..

Image

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