BOAT TAIL Drag Reduction Estimates

[RobertSmalls]

Originally Posted by aerohead

Since the hybrids have expensive MOSFET and IGFET power transistors requiring cooling,I'm at a loss for recommendations with these advanced powertrains.

Fortunately, the inverter and DC-DC converter on the Insight are located inside a Faraday cage behind the seats, where they are fan-cooled with cabin air. Under the hood, it's very simple and conventional, aside from the traction motor inside the transmission bell housing.

[aerohead]

Originally Posted by RobertSmalls

Fortunately, the inverter and DC-DC converter on the Insight are located inside a Faraday cage behind the seats, where they are fan-cooled with cabin air. Under the hood, it's very simple and conventional, aside from the traction motor inside the transmission bell housing.

Robert,that's good news.My mind envisioned something like the EV-1 and the whole black-box getting zorched.
So it looks more like a green light for blocking.

[aerohead]

I simplified a few images to help illustrate the relationship between tail truncation and drag coefficient.
Of course,the full tail gets steamline flow

With Mair's boat tail,I've divided the length into 10-equal length segments and given the percentage of original frontal area for each segment,along with it's associated drag coefficient as reported by Mair (note these Cds do not represent any skin friction).You'll notice that at around 80% length,there's no longer any drag decrease.This is indicating Morelli's 'fluid tail.'

Here is Lehmann and Kosin's fuselage,also divided into 10-equal-length segments,along with each segments associated percentage of original frontal area and drag coefficient.Again,you see the 'fluid tail' occurring at around 80%,and no appreciable drag reduction beyond 80%.

With car bodies based upon half-bodies of these shapes we'd have to superimpose the drag associated with wheelhouse and wheels,but you can clearly see the relationship with tail truncation and drag.