NACA wartime windshield drag investigation

[aerohead]

Some old-time taxpayer-funded research
http://naca.central.cranfield.ac.uk/...a-wr-l-462.pdf

[sendler]

A couple interesting observtions: Most of the designs maintain a very uniform pressure all up and down the orifice lines, and similar to what we are doing with the streamliner motorcycles and opposite to what is imortantant to cars, there was little priority given to maintaining adherance to the template shape from the side view (the X-1 form for example). So it is apparently quite possible to get extremely good aero as long as all of the points in the 3D slices of the plan view of narrow objects like a canopy or two wheeler adhere to a pure airfoil form even if the side view is less than ideal.

[freebeard]

Is this the one from the other thread?

[aerohead]

Originally Posted by sendler

A couple interesting observtions: Most of the designs maintain a very uniform pressure all up and down the orifice lines, and similar to what we are doing with the streamliner motorcycles and opposite to what is imortantant to cars, there was little priority given to maintaining adherance to the template shape from the side view (the X-1 form for example). So it is apparently quite possible to get extremely good aero as long as all of the points in the 3D slices of the plan view of narrow objects like a canopy or two wheeler adhere to a pure airfoil form even if the side view is less than ideal.

Exactly!
You'd never do a 'Kamm' canopy.And if limitations limit the aspect ratio of the trailing edge of the canopy,it's still best to fully boat-tail it.

[aerohead]

Originally Posted by freebeard

Is this the one from the other thread?

No,it's a separate research.

[freebeard]

Years ago Popular Mechanix Illustrated published a picture of a B-17 canopy grafted onto a Jeep. It worked out for width.

[sendler]

Originally Posted by aerohead

it's still best to fully boat-tail it.

The point I was trying to make: The X-1 shield doesn't fit the template anywhere along it's side view. Yet is still the most aero shape that was studied there. Because every slice of the top view is close to an ideal airfloil. Air doesn't have to pass up and over it as much as it can just go to the side. It isn't necessary for narrow shapes to fit the template in all 3 dimesions. As long as the narrowest dimension is perfect. Especially if the angle of attack in the pitch direction is always stable. As it is with our two wheeled streamliners

[freebeard]

If I get what you're saying, the Burnelli UB-14 would be an example of the narrow dimension in the vertical direction.


https://simanaitissays.com/2015/04/01/early-lifting-body-aircraft/

I have a design for a race car that is a perfect airfoil horizontally and vertically — with a different fineness ratio.



This version coincidentally has a full blister canopy.

[sendler]

Originally Posted by freebeard

If I get what you're saying, the Burnelli UB-14 would be an example of the narrow dimension in the vertical direction.

Yes. That canopy is the opposite of the streamlined motorcycles and more similar to cars where most of the air has to go up and over so the side view is the important shape to make fit the template since the wheel track prevents doing much taper from the top view. But if you can get the aero really good in two dimensions and round all of the edges, you can still have a very aero shape. Such as the solar racers.