Quote:
Originally Posted by AeroMcAeroFace
3) & 4) can't the powertrain loss be attributed under "rolling resistance" and be approximated to linear over the small amount of increase in speed though?
Why are people complaining that he is writing and selling books? BMW use air curtains and no-one on here complained that it is unfair that they are making money off innovation. I think the problem is that some people on here, and I don't believe aerohead is one of them, just seem to despise Julian for pointing out flaws in their beliefs, whether that is the template misuse, the 12-degree rule of thumb or any other rule of thumb.
|
* Sovran distinguished the unknown powertrain mechanical efficiency, only second to unknown BSFC as the two, top-tier unknowns in the eleven unknowns identified in the throttle-stop road test phenomena.
* At equilibrium, the engine is just balancing road load power absorption, plus the drivetrain losses.
* Mechanical efficiency of the driveline components are a function of transmitted power.
* As Road Load varies, so does this efficiency.
* It's an unknown quantity, the crux of the powertrain issue.
------------------------------------------------------------------------------------
* Rolling resistance is a simple linear function of load and velocity. It's a 'known quantity' once its coefficient is derived. If we had enough data for the test vehicle to reverse-engineer the coefficient of power absorption for the tires, we could just plug that in, with the 'new' velocity, compute the rolling drag and power, and have the value to work with. In this way, it could be isolated from the mix. Better book-keeping.