Aerodynamic templates wanted!

[cyclist916]

Hello. I'm looking for teardrop shapes that are non corrected for use on a land-traveling vehicle, such as this one.



It is important that they are to scale. Also, the measurements/angle for the shapes would be helpful as well. I would also be interested in any books that would have these images and/or measurements.

Thank you.

[cyclist916]

Originally Posted by Frank Lee

It's all online if you google airfoil database.

Thanks, but more specifically I'm looking for ones that are completely symmetrical, to have the very lowest .cd and not to derive any lift. Anywhere else that I can look or terms to search for?

[ChazInMT]

What are you trying to streamline? Are you aware that with a 2 dimensional shape it is very easy to get a low Cd, but optimizing the Cd on a 3 dimensional shape is hugely difficult?

[euromodder]

Originally Posted by cyclist916

Thanks, but more specifically I'm looking for ones that are completely symmetrical, to have the very lowest .cd and not to derive any lift. Anywhere else that I can look or terms to search for?

You could look for the shapes of
- AWACS rotodomes (these are very thin though)
- airships
- aircraft drop tanks like the USN Aero 1D 300 US Gal tank
Tailhook Topics: Douglas Low-drag External Fuel Tanks

- low drag general purpose bombs of the Mk 80 series (Mk 80-81-82-83-84)


Any shape will have to be a compromise of drag vs. useful volume and sheer usefulness.

Zero lift is only possible @ 0 angle of attack.
Any relative angle to the wind will give lift.

Just don't go near round

[cyclist916]

Originally Posted by euromodder

You could look for the shapes of
- AWACS rotodomes (these are very thin though)
- airships
- aircraft drop tanks like the USN Aero 1D 300 US Gal tank
Tailhook Topics: Douglas Low-drag External Fuel Tanks

- low drag general purpose bombs of the Mk 80 series (Mk 80-81-82-83-84)


Any shape will have to be a compromise of drag vs. useful volume and sheer usefulness.

Zero lift is only possible @ 0 angle of attack.
Any relative angle to the wind will give lift.

Just don't go near round

Thanks, that's just what I was looking for. The shape that I'm trying to emulate would be similar to a zeppelin or one of those external fuel tanks that you linked to. Any idea on an ideal length-to-width ratio?

[aerohead]

Originally Posted by cyclist916

Thanks, that's just what I was looking for. The shape that I'm trying to emulate would be similar to a zeppelin or one of those external fuel tanks that you linked to. Any idea on an ideal length-to-width ratio?

If you'll look at the 'Aerodynamic Streamlining Template' thread and look through all of it you'll find some tables from Sighard Hoerner's book,'Aerodynamic Drag.'
In his 1951 Edition you'd be looking for Fig.5.13.'Frontal drag coefficient of three-dimensional bodies,depending upon their fineness ratio.'
You'll find your drag minimum here.
---------------------------------------------------------------------------As far as lift goes,most automobile lift is associated with flow separation.Since Hoerner's bodies are incapable of separation,they will not produce lift as it is commonly conceived.
A note of caution: for bluff body road vehicle aerodynamics you'll need to look at W.A.Mair's boat tail research published in the November,1969,AERONAUTICAL QUARTERLY,PP 307-320.This research will limit your choices for fineness ratios.You can see Mair's work in Hucho's books.

[euromodder]

Originally Posted by cyclist916

The shape that I'm trying to emulate would be similar to a zeppelin or one of those external fuel tanks that you linked to.

These are also relatively thin, so in order to be useful, they need to be quite long.

Impractically long if you want to use it for what your screenname may suggest : a HPV ?

Any idea on an ideal length-to-width ratio?

It all depends on what you want to do with it.

If you want a road-going HPV, the Velomobiel Quest is near the thinnest shape to be still practical.
But even that proved too long in Europe, so they made a shorter Mango / Strada version.

If you were to go racing on closed tracks, you could go thinner and longer.