Aerodynamics of world record HPV

[veloman]

I extrapolated the frontal area and coefficient of drag Sam Wittingham's streamliner which is seen below going 82mph on about 450 watts of power at about 6,000ft elevation I believe.

http://www.youtube.com/watch?v=PMUNOLwW0io

And here is about the amount of power it takes to move it at 30mph, at sea level, (see bottom)

Frontal Area 0.18 m2
Coefficient Wind Drag 0.07 dimensionless
Air Density 1.226 kg/m3
Weight 100.0 kg
Coefficient of Rolling 0.004 dimensionless
Grade 0.000 decimal
Wind Resistance 1.4 kg m/s2
Rolling Resistance 3.9 kg m/s2
Slope Force 0.0 kg m/s2
Cadence 100. rev/min
Crank Length 170. mm
Pedal Speed 1.78 m/s
Average Pedal Force 40.0 kg m/s2
Effective Pedaling Range 70. degree
Effective Pedal Force 102.9 kg m/s2
Speed 13.41 m/s
Power 71.2 watts



I can imagine riding such a machine around on normal roads: I'd either be pushing the pedals hard when accelerating up to crazy speeds then coasting FOREVER (assuming not an uphill).

Damn I want one. Put a big outrunner on it and outrun the cops on the highway (until I crashed horrible at like 150mph).

 

[LI-ghtcycle]

Makes me wana go put a Go One 3 on layaway, even if it would take me 5yrs to buy it. :lol:

Just amazing hearing that guy fly by sounding like a jet fighter!

Anyone have some CF and Kevlar cloth just laying around? I might just start making my own version ... (at least I can dream :wink: )

 

[hydro-one]

That is so cool!! It actually sounds like jet too!! i want to see these things on the road!!!

 

[John in CR]

I'd want more comfort, something like an electric version of the Monotracer http://monotracer.peraves.ch/

View attachment Monotracer.JPG

 

[LI-ghtcycle]

Yeah, I think there needs to be something in-between, less cramped than the Go One, and have better visibility/cabin venting but I'd like it to be closer to an E-bike (bicycle) than a motorcycle. Not to say I wouldn't have one for around town and low speeds and one for highway like the monotracer.

I'd love to go for a ride in one of those, I wonder how it feels to lean over in that thing like a motorcycle, must be a little freaky at first!

 

[AussieJester]

Love this comment on YouTube "When it hits 88 mph, you're gonna see some serious shit. " (for those that haven't
seen the movie Back to the Future? The DeLorean had to hit 88mph before time travel happened.)

Im with John too, looks too uncomfortable for daily use.

KiM

 

[madact]

Speed 13.41 m/s
Power 71.2 watts

OK, I know I shouldn't but I just cant resist... told you so .

The bikes they use for record-setting are indeed rather cramped - but a trike with a slightly larger body is actually pretty nice, comfort wise - you might need half again as much power for the wider body, but that's still not much (and hey, that's what the motor is for :wink. A trike like the Go-One is like an easy-chair on wheels - and if you think about how much you can move your arms around when you're in the passenger seat of a car (without opening the window, that is), it's really no worse off.

For anyone interested, I'm starting construction of a simple, robust steel-framed streamliner trike next weekend (weather permitting) - will post a build log of this, and the motor to go with it. It won't be especially light :lol: I'm aiming for about 20kg sans fairing, but I'm 110kg and I plan to ride it long-distance, so I don't want it breaking - and it has to meet local racing rules too, so there'll be roll-bars and side-intrusion bars and seatbelts and frontal impact protection etc. etc. Body shell shape is TBD (still working on getting a decent aerodynamic simulation up and running), but the frame design is pretty much finalised. Would have started this weekend, but it only just cleared up enough for me to build my workbench :?

 

[veloman]

Yeah, it's definitely cramped in that speed record streamliner, from the pics I saw. google 'varna diablo'

I'd like to build such a machine, or more likely a velomobile like that Go-One. Good solution to cold/wet weather!

Make sure you post pics of your build, madact. Check out bentrideronline.com and go to the homebuilders forum :wink:

 

[coln72]

or check out some of the photos on the RACV Energy Breakthrough site - link below.

Actually surprised to see exposed wheels front and rear......guess there is a reason for it

 

[AussieJester]

- will post a build log of this, and the motor to go with it.

WOOT another custom project to follow! Best of luck with the fabrication mate...what motor will you be running? please don't say a frock motor :lol:

KiM

 

[Matthijs]

Im with John too, looks too uncomfortable for daily use.
KiM

The designer of the Varna Diablo says when it is to comfortable it is to big for the rider. Those things are meant to be uncomfortable for the gain of speed.

 

[LI-ghtcycle]

Great ESPN article about Sam's record breaking run. 8)

[youtube]jQwpGLCAMm4[/youtube]

ESPN Article on the record run and description of the crash!

http://sports.espn.go.com/espnmag/story?id=3405498

I found a link to pics of the Varna Diablo crash aftermath:

http://www.fortebikes.com/gosamgo/A3/rider/Rmedia.html

A pic of Sam getting set-up about to be sealed inside with velcro and hockey tape. Man, they do this in Sept. in Nevada that sucker has to be HOT inside!!

They had to use 24" wheels for this configuration since a larger wheel would have put it out of reach of Sam's legs.

http://www.popsci.com/diy/article/2005-10/worlds-fastest-bike

 

[rolf_w]

I'd want more comfort, something like an electric version of the Monotracer http://monotracer.peraves.ch/

here it is: http://www.zerotracer.com/

 

[docnjoj]

Sorry guys but I still think the Dutch Drymer vaporcycle beats them all. I feel like Sam Whittingham looks after a 15 mile ride! And I thought it was just being old!
otherDoc

 

[LI-ghtcycle]

You mean this one, docnjoj?

 

[veloman]

I'd want more comfort, something like an electric version of the Monotracer http://monotracer.peraves.ch/

here it is: http://www.zerotracer.com/

Website says it's consumption at 80kph is 7kwh? That's about the same power my car takes to move at the speed, I think. Seems quite high for such an efficient machine. 7,000watts for 55mph? That's about 9hp.

640kg weight.

I guess you need that weight for stability at highway+ speeds, with such a surface area on the sides.

 

[madact]

or check out some of the photos on the RACV Energy Breakthrough site - link below.

Actually surprised to see exposed wheels front and rear......guess there is a reason for it

Yep. That's what you get when school kids build velomobiles - I did it too , the reasoning tends to involve easy access (when many teams don't even have spare wheels anyway), simplifying construction (you can actually get away with more with internal wheels), and being able to make the body narrower (never mind having a pair of eggbeaters hanging in the wind, and the effects of the top of the wheel moving twice as fast in the airstream as the car body).

I'd want more comfort, something like an electric version of the Monotracer http://monotracer.peraves.ch/

here it is: http://www.zerotracer.com/

Website says it's consumption at 80kph is 7kwh? That's about the same power my car takes to move at the speed, I think. Seems quite high for such an efficient machine. 7,000watts for 55mph? That's about 9hp.

I'm not that surprised - for all it's sleek lines, the designers have committed a veritable catalogue of aerodynamic sins, starting with those rear-view mirrors (at least don't make them flat plates! A little depth to the leading edge, for pity's sake) and leaving the windscreen wiber hanging out in the breeze (OMFG what were they thinking?). Just those two and you have instant large-scale turbulence over most of the body, with premature separation, increased skin drag and the rest of it. Then the rest of the body - those nice crisp edges are going to **** you up big time anyway. That big concave scoop on the side is curving in entirely the wrong direction for both drag and inlet flow, and could be a lot smaller for the same function to boot, if they had it curved correctly (not to mention they probably don't need it for cooling at all, on the electric). The 'fastback' area won't maintain low-angle attached flow (which is desirable in this case given the 15 degree-or-so rake) with the air coming back around the sides, and the rear end is the classic bluff-body trailing edge shape, but too thin to set up a recirculation cell. The only thing to like from an aerodynamic point of view (apart from the overall shape and small frontal cross-section) is the nicely-executed set of NACA ducts below the window - but they do you no good if you stick them in the wake of the mirrors, as happens here. I can only say that it looks like it was designed by a motorbike manufacturer :? . It's also heavier than some small cars...

In the CSIRO's paper on their axial flux solar-car motor, they state "A well designed car can potentially average 100 km/h. A typical internal combustion engine road car at this speed uses about 35 kW" - as air resistance tends to increase with the cube of velocity (very crudely, presuming no change in flow states - which is a good assumption here), upping the speed from 80kph to 100kph would yeild a power consumption of 1.95 * 7kW -> ca. 14kW at 100kph (no idea where the extra 'h' on the web page comes from). Drag also tends to vary linearly with cross sectional area, and this thing looks like it has a bit under half the cross sectional area of a car, and a bit under half the drag - so, big woop, they've designed something which is exactly as well tuned aerodynamically as (or slightly worse than) a "typical internal combustion engine road car" - but smaller!

Given the layout and overall shape of the vehicle, they could do better by a very large factor - I'd say aiming for 5kW at 100kph would be not unreasonable, even with the requirement of having mirrors - and tripling the range (not to mention increasing the top speed ) has got to be worth the effort, right?

 

[docnjoj]

You mean this one, docnjoj?

Yep! I am actually willing to buy one but I can't find one that exists for production and Drymer never answers their E-mail. I don't think it can go as fast as Sam's velo though!
otherDoc

 

[Matthijs]

I am not really impressed by the Drymer. I saw them in Amsterdam last year and was able to sit on the one with the roof on it. Price wise they are pretty expensive. Between €3000 and €6000 and their topspeed is 25 km/h. With the lightest version being 60 kilo's they are far from lightweight as well.

Build quality seems pretty good though.

 

[docnjoj]

I am not really impressed by the Drymer. I saw them in Amsterdam last year and was able to sit on the one with the roof on it. Price wise they are pretty expensive. Between €3000 and €6000 and their topspeed is 25 km/h. With the lightest version being 60 kilo's they are far from lightweight as well.

Build quality seems pretty good though.

Most trikes are simply too low for traffic, including mine. I thought that Drymer had a good solution, albeit an expensive one to this problem. If I could find one in this country and test ride it, I would probably buy it if it proved worthy. Thanks for your input,Matthijs. 60 kilos is a lot of weight but my Steintrike with motor and batteries weighs 40.
otherDoc

 

[LI-ghtcycle]

I am not really impressed by the Drymer. I saw them in Amsterdam last year and was able to sit on the one with the roof on it. Price wise they are pretty expensive. Between €3000 and €6000 and their topspeed is 25 km/h. With the lightest version being 60 kilo's they are far from lightweight as well.

Build quality seems pretty good though.

I like the concept of the Drymer, but not the looks. WOW!! 60 kilos?! (132 lbs?!) and that's before adding any electrics!

I wonder if there is anything that looks more like a Go One in styling, but is a bit more up-right and visible, probably too much of a compromise to keep the look. :wink:

Kinda like when I bought what I thought was my dream bike (2001 Kawasaki ZX9R 900cc Ninja) and realized it really wasn't with my back hurting from the riding position, power so crazy I never felt comfortable pushing it through corners, and the riding position making it feel top-heavy and actually now I realize the ride height was way high for my 5'8" and I led to being the first bike I ever had tip-over on me in a parking lot!

Is there a more up-right velo similar to the Go One's styling? If not, and if I could either build my own version or buy a poor man's version of that and add some visibility flags, that would be my choice.

 

[JennyB]

Given the layout and overall shape of the vehicle, they could do better by a very large factor - I'd say aiming for 5kW at 100kph would be not unreasonable, even with the requirement of having mirrors - and tripling the range (not to mention increasing the top speed ) has got to be worth the effort, right?

Not unreasonable at all. This much more modest streamliner (built by a velomobile designer) takes only 2.4 kw at 55 mph. 8)

 

[veloman]

Running "my" numbers for my standard UCI legal road racing bike, I get 3kw requirement for 55mph.

Frontal Area 0.65 m2
Coefficient Wind Drag 0.50 dimensionless
Air Density 1.226 kg/m3
Weight 91.0 kg
Coefficient of Rolling 0.004 dimensionless
Grade 0.000 decimal
Wind Resistance 120.1 kg m/s2
Rolling Resistance 3.6 kg m/s2
Slope Force 0.0 kg m/s2
Cadence 100. rev/min
Crank Length 170. mm
Pedal Speed 1.78 m/s
Average Pedal Force 1705.1 kg m/s2
Effective Pedaling Range 70. degree
Effective Pedal Force 4384.5 kg m/s2
Speed 24.55 m/s
Power 3035.4 watts

And here's 70mph: 8.2hp for road cyclist. That's exactly DOUBLE the power to go 27% faster!!!

Frontal Area 0.65 m2
Coefficient Wind Drag 0.50 dimensionless
Air Density 1.226 kg/m3
Weight 91.0 kg
Coefficient of Rolling 0.004 dimensionless
Grade 0.000 decimal
Wind Resistance 194.6 kg m/s2
Rolling Resistance 3.6 kg m/s2
Slope Force 0.0 kg m/s2
Cadence 100. rev/min
Crank Length 170. mm
Pedal Speed 1.78 m/s
Average Pedal Force 3477.9 kg m/s2
Effective Pedaling Range 70. degree
Effective Pedal Force 8943.1 kg m/s2
Speed 31.25 m/s
Power 6191.4 watts


It's disgusting how my power requirements actually head up towards half of what a small car draws at highway speeds, even though I'm 200lbs bike+rider, and have drastically less frontal area. It just goes to show how poorly aerodynamic traditional road racing bikes/riders are. So much turbulence. Now think of a typical casual cyclist or most of you ebikers wearing casual clothes and sitting upright..... power requirements are probably nearly the same for you as they are for a Geo Metro, when at 70mph. Slip into Sam's streamliner and power is 6% of that.

 

[docnjoj]

LI-ghtcycle wrote:
"I like the concept of the Drymer, but not the looks. WOW!! 60 kilos?! (132 lbs?!) and that's before adding any electrics!"


I believe that weight is with electrics since the Drymer comes with them installed. It is still heavy but not unreasonable.
otherDoc

 

[bzhwindtalker]

Any thougths on my velo's aerodynamics? I know the wheels outside is a big aero breaker but




looks big in the pics but it's really compact. Most of the frame will be covered with fabric or Dacron; I expect 10wh/km with good pedaling, first tests showed 22wh/km with hard pedaling, but that was unfaired and with the tire-eating steering that will be reworked!