coastdown software
 

If there is any interest around here, and no previous solution, I am interested in writing a software package to calculate CdA and rolling resistance. I plan on using the usb-gps module that came with my Microsoft Streets and Trips software, and writing the software in VB6 for simplicity.

My expected usage will go something like this:
1. find a long, flat, straight, level, little-used road in the country
2. wait for a windless day
3. get up to speed (faster is better, but lets not make the evening news)
4. pop it into neutral
5. click "go" on your laptop
6. wait till the car stops

I can use the gps to give me speed updates every second and calculate CdA from that. I expect it would take me about 5 hours of work plus 10 hours of research (interface to gps, re-learn vb coding).

I'd be a big time hypocrit if I charged for the software, so of course it would be free for distrobution.

Funny you should bring this up. On the mpguino todo list is to ask for the cars weight and to have the user coast from 50mph to zero and have the mpguino print out their cdA. It should make you at least do the coast down in both directions though and take the averages.

ref: http://ecomodder.com/forum/showthrea...html#post21662

so yeah... funny that.

I was actually meaning to read up on that. I am a computer engineer and I work with embedded systems programming every day. Maybe I should get up to speed on that.:turtle:

I think I'm still going to write the gps one for the fun of it. Some people might find it easier to use.

THANKS :thumbup:

FYI, iwilltry put an instructable and spreadsheet together on the subject:
Measure the drag coefficient of your car - Instructables - DIY, How To, ride

Might be neat to use VB to track the values from the GPS and regenerate the graph.