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Old 10-05-2015, 07:22 PM   #122 (permalink)
aerohead
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optimum

Quote:
Originally Posted by orengomotors View Post
well, let's do it! a gravity powered belly tank.
whats the optimum longitudinal shape of the belly tank? i found a lot of different belly tanks on internet.
The answer is problematic:
*belly or wing tanks are designed for flight conditions,far above the ground in thinner air.And they are optimized for frontal area and tend to be 'long' in relation to their diameter.
*In ground proximity the drag of a body doubles,so a Cd 0.05 tank might be Cd 0.10 in ground effect.
*Lay tested a 'tank' close to the ground and got Cd 0.08.
Your looking for the minimum envelope which will enclose you and your mechanical components with the smallest frontal area,but full attached flow.
It's going to be like this Soapbox Derby racer,but with a canopy/head fairing

Here are some racing bicycles

The Edison-II car body would work great for you





The 2.5:1 ratio streamline body has about the lowest drag but if you size it to the length of your rig I don't think it will work for you.
I just cut up my Lockheed T-33 wing tank for scrap.It was 610mm diameter and about 6095mm length.
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