Speed Holes for MPG?

[freebeard]

What I am certain of:
There's a hell of a lot of exhaust gas coming out of an engine, so using it to both 'fill' this vacuum and draw out the the exhaust makes sense.

This inspired me to dig out the .OBJ of a Beetle I used a decade ago to model a Coanda nozzle boat tail built on a 4-into-2-into-1 header. We shall see how long it takes to have something to show.

editL

Figure 1. Typical flow topology in a shallow open cavity.

This is the case for the pickup truck half-tonneau.

[Logic]

Originally Posted by freebeard

This inspired me to dig out the .OBJ of a Beetle I used a decade ago to model a Coanda nozzle boat tail built on a 4-into-2-into-1 header. We shall see how long it takes to have something to show.

editL


This is the case for the pickup truck half-tonneau.

I've seen your pics:


A bit more than speed holes but I like

Apparently heat on/from the trailing edge of a wing = boat tail helps..??
Hot air takes up more space in the vacuum..?

Either way; cutting the tip off that cone, about a 3rd shorter and exhausting into it would be interesting.

Blown wings that keep the flow attached at higher angles of attack are a very good bet.
If your boat tail is thought of as a bit of wing trailing edge; A higher angle of attack = a shorter, lighter boat tail...
At a guess; if you want to 'blow' a 'shallow' boat tail, the (laminar flow) nozzle needs to be designed by a better aerodynamicist than I!
I do NB that the nozzles usually start at around the point where flow separation begins to occur and blow parallel to the rest of the trailing edge.

Ducts in/on the front of the rear fenders, through a Meredith-ish? Effect radiator duct that blows out the chopped back.
Think the left beetle, with aero fender vents where the air is Meredith Effect warmed by the engine fins before exhausting out the open back, sans that cylinder bit. (Maybe a bit shorter=bigger opening.
You'd be able the peak out the back with your rear-view mirror to.

The physics on Ram Jets is a high a pressure/volume bit of the laminar AERO shaped/designed vent just ahead of the heat source. I think that's the basic idea.

This boils down to a means to using waste heat and exhaust flow in a short, cambacked open boat tail, rather than throwing it away...

(Every time I see a beetle i think this (bigger) as a windscreen from the nose back, trimmed/flattened to the original roofline:
Perhaps 'sides' could be attached or ordered to one of these? )

[freebeard]

Thanks. The upper right Beetle was to mimic the work Breers did at Chrysler in the 1930s.

The Coanda nozzle lower left follows this unattributed pic:


Instead of speed holes for the Beetle's fenders, I prefer this from Harry Bradley, Jr.:



Something similar for the flat windshield:

[bandit86]

Originally Posted by freebeard

Thanks. The upper right Beetle was to mimic the work Breers did at Chrysler in the 1930s.

The Coanda nozzle lower left follows this unattributed pic:


Instead of speed holes for the Beetle's fenders, I prefer this from Harry Bradley, Jr.:



Something similar for the flat windshield:

That last pic almost looks like the Mitsubishi EV

[freebeard]

Which? The MiEV?

It actually follows the Dick Dean Shalako:


https://barnfinds.com/wp-content/upl...ig-630x427.jpg