My musings in the direction of building an electric vehicle capable of my 70.4 mile 2 hour round trip commute, with significant portions at 65mph, and the rest including a lot of curves, and about 10 stops each way.
DIY Electric Car thread (latest)

• $1,650, Batteries, Thunder Sky 60 Ah x 3.2 v x 22 cells = 4224.0 watt hours, 50.6kg (111.6lb).
  97.6% of my way to work, at the E-Tracer's efficiency. Likely to change type / brand of cell. 3.35v resting?
• $485, Motor, Mars 0709, 72v 125 amps (9kW) continuous, 3,000 rpm, 16kg (36lb).
• $600, Controller, Paul & Sabrina's 144v 500amp DC EV Motor Controller Kit, aka Open Re-Volt, 144v @ 500 amps, 5kg (11lb).
• Charger
• 12v battery, YT12A-BS

Thoughts on cars:

• Use commonly available low rolling resistance tires, and wheels of whatever car they're designed for. Looks like Bridgestone/Firestone B381 P185/70R14
• Tiny diesel engine would be nice.
• A long tail lopped off at 50% of the car's maximum cross section would probably be good - a Kamm tail

Beetle gear ratios: http://members.home.nl/pj.kansen/vwbz/Gears.html
Quaife Reversing Differential

2012-01-25
http://www.gizmag.com/go/4272/ diesel motorcycles
http://www.treehugger.com/cars/souped-down-1959-opel-t-1-gets-37659-mpg.html 367mpg 1959 Opel T-1
http://www.treehugger.com/cars/volkswagen-to-make-limited-edition-of-1-liter-car-282-mpg-in-2010.html VW 1 liter car
http://www.gizmag.com/yamaha-y125-concept-retro-220-mpg/20672/ Yamaha 125cc concept

2012-01-10

Bill Noble's Caracal D, only SCCA Formula Vee with a roof?

2011-03-24

2011-03-23

Kamm tail.

1986 Oldsmobile Aerotech, longtail. This is what aerodynamic looks like without a Kamm tail.

Tandem seating.

2011-03-22
A Kammback / Kamm tail / K-tail body has "...a smoothly contoured front that continues to an abrupt vertical flat surface in the rear." "The airflow, once given the suggestion of the beginning of a turbulence-eliminating streamlined teardrop tail, tended to flow in an approximation of that manner regardless of the fact that the entire tail wasn't there. This is called the Kamm effect." - wikipedia
(Term introduced to me by John.)

The first time aerodynamics was applied to production cars was the 1934 Chrysler Airflow. Buyers were so disinterested that it's no surprise manufacturers mostly haven't bothered trying since. The Aero Civic has a significantly better coefficient of drag (0.17) than the Prius (0.26) and Insight (0.25), even better than the EV1 (0.195). And it's just a Civic with a bunch of cheap coroplast added without the aid of Computational Fluid Dynamics or a wind tunnel.

2011-03-21
"Generally, for theoretical and experimental purposes, gases are assumed to be incompressible when they are moving at low speeds--under approximately 220 miles per hour. The motion of the object traveling through the air at such speed does not affect the density of the air." - http://www.centennialofflight.gov/essay/Dictionary/Compressibility/DI136.htm

"Compressible flow can with good accuracy be approximated as incompressible for steady flow if the Mach number is below 0.3." - http://www.cfd-online.com/Wiki/Incompressible_flow

Mach 0.3 = 367.5 kph = 228.4 mph.

I've been thinking, what fun would it be to prove that an electric vehicle can be built for $3,000, if nobody would want to use it, like the bike design I've been working on?

2011-03-17

I think bending that pipe would be hard. And I think cutting and welding it should be fine.

2011-03-16

2011-03-15

Focusing link based steering. Leading link fork, except instead of a normal steering head with a pair of circular bearings at the top, it has a single spherical bearing (heim joint?), and the bottom of the forks are positioned by another pair of links with a virtual pivot.

2011-03-14
Feet forward steering
Steering and front suspension is a common problem with feet forward motorcycle designs (which this project often is). Normal motorcycle steering is something like twice the height of the front tire, which is too high. Options:

Single sided front swingarm, as used in the Yamaha GTS1000. Hub is horizontally offset from the center making room for the steering pivot in the center.

Hub center steering, as used in the Quasar. Large centered non-rotating hub surrounded by bearings, with a steering pivot in the center.

Double wishbone, as used by ProjectVF. The extreemly common car suspension rotated 90°. Taller than the other options listed here, but still a significant imrovement in height.

Focusing link. Steering pivot is virtual, created by several swingarms. I just discovered this one, and I'm kind of excited about it.

Buddfabb streamliner, 50cc land speed record holder, 233kph (145mph).

"To keep the front end low we use one sperical bearing at the top of the fork and control arms at the bottom. The geometry of the arms create a virtual center combined with the top bearing makes a steering angle of 28 deg."
Update 2011-03-17: The control arm arrangement qualifies as a "four-bar linkage".

2011-03-13

2011-03-10

60 Ah x 3.2 v x 22 cells = 4224.0 watt hours = 97.6% of my way to work, at the E-Tracer's efficiency.

2011-03-08
I've been thinking and reading about the MonoTracer, previously known as the EcoMobile, particularly the X-Tracer / E-Tracer electric version that won its category in the Automotive X Prize. A cabin motorcycle.

They're talking about 123 watt hours per mile on the highway. Based on that, I'm figuring one way (56.6 km, 35.2 mi), my commute would be $1,692 and 48 kg (107 lb) of lithium ion cells. And maybe I could wheel that into my office to charge every day? Same thing I was thinking the last few times I did a two wheeled rendering, including the shell. I think I'd prefer trap doors for my feet instead of outriggers.

2011-03-04
Occasionally the weight considerations resulting from gasoline having 46 times the energy density (by weight) of lithium batteries, or 331 times that of lead acid, gets me down, and I think about things like motorcycle engines again.
(Update 2011-03-08) " electric motors are well over 90% efficient while hydrocarbon fueled vehicles are about 18%." - http://peraves.files.wordpress.com/2010/10/x-prize_article_bimmer_rick_rys.pdf. This changes the numbers to 9.2x for lithium and 66.2x for lead acid. Which might look pretty good for lithium when you consider the weight of gasoline engines.

There are racing classes of cars that use motorcycle engines, with mid-rear engine placement:
Formula SAE - a student design competition
DSR (SCCA D Sports Racing) - Stohr is a very successful manufacturer.

Also, this Mercedes Benz SilverFlow concept is sexy as hell:

At the moment, I want to build something very much like it with a Honda CBR 1000 engine and full tilting suspension (although with a much smoother exterior).

Peugeot LiiON concept:

2011-03-03
Torsen differentials from Audi Quattros seem to be popular for Formula SAE: http://www.torsen.com/fsae/fsaefaq.htm. There's also Quaife: http://www.vaughanscott.com/DSR/index.htm http://www.smallfortuneracing.com/ProductsAndServices/Components/Components.html

2011-02-25
The Destiny Parts electrathon land speed record holder.

The rotation speed of a DC motor is proportional to voltage. The ratio of voltage to rotation is determined by the number of Turns. Fewer Turns = faster rotation per volt. EnerTrac hub motors use two or three turns.

Turns: Turns refers to the number of times the wire is wound around each armature arm. The fewer the turns the higher the RPM or top end speed.So you want more speed choose a motor with fewest number of turns. Keep in mind that fewer turns requires greater battery draw.

Winds: Winds refers to the number odf Strands of wire wound around the armature. The fewer number of winds the faster the accelration, higher number of winds the higher top end speed you will have.

2011-02-24
Moped wheels with a 1/2" or 12mm axle bolt (spindle) and nut, with cotter pin, from one side. Replace wheel bearings with cartridge bearing assemblies from bearing supply stores.

An electrathon is a competition to see how far you can go in one hour on two commercial lead acid batteries (maximum 73 pounds (33kg)), two car batteries. Current record is 62 miles, by C. Michael Lewis. The Electrathan America handbook has great tips.

Spent some time looking at the air tunnels between the driver and wheels in 24 Hours of Le Mans cars, effectively reducing frontal surface area.

Moved batteries in line with wheels. Wheels and batteries have separate farings from the driver and motor, attached rigidly. Suspension by single sided swingarms all around.

Haven't worked out the frame details, or added clearance for the swingarms.

Need to keep anti-roll bars in mind.

I'm thinking, for the front wheels, wheel skirts that open up for turning, roughly like the AeroCivic.

I occasionally wonder about moving the driver to the left pod, and the batteries all to the right. Probably not what I'll end up doing, but it needed to be modelled. Making it a two seater, with one person on each side, would remind you of the Star Wars twin pod cloud car. Although this was inspired entirely by aerodynamics, and the similarity is just a coincidence.

2011-02-19

2011-02-18

2011-02-17
AeroCivic front wheel skirts - pushed open by tires when turning, with rollers.

2011-02-16
"A car needs body roll during cornering to transfer weight downward onto the outside tire contact patches. This is the result of a lower front roll center. if weight was transferred laterally to the tires the rubber would shear across the track surface and the car would slide out...or , in round track tech terms..it would push like a freight train. No grip!" - physicsforums.com

2011-02-15

Electric recumbant motorcycle.

Cheap specs:

Initial specs:

Possible final specs:

In the last revision I moved the rider's head up to add rear suspension clearance. I didn't like that. So here I added clearance by moving the rear wheel back. I was also convinced wood wouldn't be good. This would probably be difficult to turn through an intersection.

Wood.

A pair of EnerTrac hub motors and a 144 cell battery pack. No gears. Entire drive train is one moving part per wheel.

Double wishbone suspension with a steering linkage pivot intersecting the wishbone pivots.

"Make it lighter so you can make it lighter."
Small test battery pack: Headway 10Ah 3.2v x 22 = ~72v.

Nobody.

22 Thundery Sky 40ah 3.2v cells.

6 Trojan T-1275 cells. Ohh, texture mapping.

What if I moved the batteries to a driven trailer?

Body with two wheels.

Two wheels.

Frame.

Body. Nurbs surfaces are fun.

Single seat layout progress.

Switch to single seat.

More front wheel detail.

Getting carried away with fun with light.

Pink, hah!

Internals.

Switched from lithium to lead acid batteries for substantial cost reduction. Moved batteries to pontoons, shortened body.

Started building wind tunnel.

I don't believe the teardrop is actually most aerodynamic.

More conventional aerodynamic shape.

To do:

• Modelling
  • Generate printable sides of 3D models
  • Pontoon attachment
  • Brakes
  • Steering
  • Mirrors
  • Pedals
  • Calculate CG, tip angle
  • Motor mounts
  • Suspension mounts
  • Controller and charger mounts
  • Seats
  • Trailer hitch (for grocery shopping)
• Prototyping
  • Side load test wheels
  • Build mockup of car to test fit people
  • Finish wind tunnel
  • Test various shapes in wind tunnel, including angles accounting for cross wind (for barrier layer separation)
• Parts decisions
  • Pick brakes
  • Pick wheels, tires
  • Pick headlights and blinkers
  • Pick shocks / springs
  • Calculate gear ratio
  • Pick suspension parts, steering, gears, chain / belt
  • Windshield
• Fabrication
  • Try tig welding
  • Buy tig welder
  • Learn to weld
  • Make English wheel
  • Practice English wheel
  • Build car

Definitions: http://www.gencourt.state.nh.us/rsa/html/NHTOC/NHTOC-XXI-259.htm

http://www.gencourt.state.nh.us/rules/state_agencies/saf-c3200.html

Federal / DOT rules: http://www.fmcsa.dot.gov/rules-regulations/administration/fmcsr/fmcsrguide.aspx

http://www.fmcsa.dot.gov/rules-regulations/administration/fmcsr/fmcsrruletext.aspx?chunkkey=090163348002392b

Anything with three wheels is a motorcycyle, except tractors and mopes.

Multi-piece windshields are allowed.

windows
Glazing material may be purchased from manufacturers, intended to be cut to shape.
"meet the requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 205"
http://www.carwindshields.info/FMVSS205.htm
"shall be marked in accordance with FMVSS No. 205 (49 CFR 571.205, S6)."
Custom: "Mark that material in accordance with section 7 of ANSI/SAE Z26.1–1996;
"A copy of ANSI/SAE Z26.1-1996 may be obtained from the Society of Automotive Engineers, Inc., 400 Commonwealth Drive, Warrendale, PA 15096-0007. A copy of ANSI/SAE Z26.1- 1996 may be inspected at NHTSA's technical reference library, 400 Seventh Street, SW., Room 5109, Washington, DC or at the Office of the Federal Register, 900 North Capitol Street, NW., Suite 700, Washington, DC."
Costs $61
SAE J673

http://www.fmcsa.dot.gov/rules-regulations/administration/fmcsr/FmcsrGuideDetails.aspx?menukey=571 Federal safety standards

Federal:
Brake system must have a failure warning light
Part 571.122: Standard No. 122; Motorcycle brake systems.
S5.1.4 Parking brake. Each three-wheeled motorcycle shall be equipped with a parking brake of a friction type with a solely mechanical means to retain engagement.
Max brake pedal force is 90 pounds for foot operated.
Requires engine kill switch
illuminate speedometer

http://reversetrike.com/

http://www.youtube.com/watch?v=a9d3wAjdknA
http://ecomodder.com/forum/showthread.php/mark-kings-electric-car-9094.html
http://gallery.me.com/benhdvideoguy#101520&view=grid&bgcolor=black&sel=6
http://www.kitsapsun.com/news/2009/jul/02/desire-to-be-green-and-park-cheaply-sparked/

http://www.electricmotion.org/ Lifan based motorcycle, under US$3,000.