Quote:
Originally Posted by kach22i
I know this thread has been scrubbed, but it brought up some interesting issues.
Explain to me again how this design below can stray from the 2.8 degree rule.
Aptera Comes Back from The Dead | Design Engine
Just eyeballing underbody looks to be plus or minus 15 degree average.
Bottom of rear wheel faring almost an 30 degree tangent. |
It's the 1947 NACA 2-D numerical/Morelli shape,which is a special structure.
As a reflexed airfoil in ground proximity it could do Cd 0.05,compared to Cd 0.08 for a streamline half-body.
As more of a 'car' body,Morelli could get it to Cd 0.171 with the small truncation,but it swelled to Cd 0.35 when wheels were added.
Only wheel integration,via wheel fairings got a viable passenger car variant to Cd 0.205.
As the Aptera,at the X-Prize competition she was Cd 0.15(?),requiring the optimized (high) ground clearance.
I'll never know why it failed to attract more of a following.And with wheels,I'm uncertain that it has any drag advantage compared to more 'conventional' low drag forms.
The cost of producing a DOT-rated, laminated safety glass windshield alone,may have have scared people off.Hucho discusses this issue in his book.