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Old 01-27-2021, 11:17 AM   #13 (permalink)
aerohead
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2-6

Quote:
Originally Posted by AeroMcAeroFace View Post
2-3) I think they will be a linear thing and can be all integrated into "rolling resistance"

4) Mechanical resistance is maybe 5% of the total drag, even if it changes by an extreme 10% it is only 5.5% of total drag and so while not irrelevant it is not a huge difference.

5) BSFC if it does change will be tiny and I believe will be negligible over the few percent increase/decrease in engine speed.

6) Wind, well nothing can change that, but on a calm day I see no problem with multiple bidirectional averaged runs a-b-a-b-a-b as a minimum. So, just don't do it on a particularly windy day, unless you are specifically testing crosswind drag.
2) engine accessory power absorption would be linear if belt driven
3) rolling resistance would be linear all the way to standing wave, beyond the performance envelope of the vehicle
4) I have 8% powertrain loss for an overdrive, manual transaxle powertrain, like the gen-I Insight. It's not as significant as BSFC, although, rates #2 in Sovran's research.
5) A BSFC map for the specific test vehicle would be welcome. This is the #1 bone of contention in Sovran's SAE Paper. It must be known in order to sort out any actual benefit of an aerodynamic modification, lacking gear-matching
6) Wind is really problematic. Datalogging would be imperative if one were to undertake testing during wind.
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