Quote:
Originally Posted by mnmarcus
I believe it was a tuna.. presumably travelling in salt water at whatever speed a tuna swims at. It probably did not take into account the locamotion of the tuna being side to side tail motion (maybe skewing the results towards longer=better).
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It would be nice to see a 'technical' drawing of the bluefin tuna,lowest drag form of the tuna.
A plan view would give us the most important view,fixing the maximum camber point for side body flow ( where the majority of water travels ).
My texts which cover fish and shark put the maximum cross-section ( frontal area ) at approx. 1/3 rd body length,with the remainder of the fish the boat-tail portion.
The bluefin is supposed to have the lowest drag of fish.The shortfin mako is supposed to be the lowest drag shark.The sailfish is supposed to be the fastest fish.Bottlenose-dolphin,the fastest dolphin.The gentoo penguin is said to have the lowest drag coefficient ever recorded for an organic underwater structure.The perigrine falcon is the lowest drag and fastest bird,in full stoop,at around 257-mph.In India,a particular type of swift was reported at over 200-mph in level flight.
They're all teardrop or fusiform ( spindle-like ) in body structure.
One of the members shared the NUNA solar car with us.It's makers claim Cd 0.07,a remarkable acheivement! That car has every component fully boat-tailed either in plan or elevation.You can argue over it's practicality as a daily driver,crashworthiness,etc.
The 'laminar' forms,which move the max camber location aft do provide more laminar body area but it's important to remember that with cars,separated flow is the bogeyman,not skin friction.And ground-effect can compromise laminar structures.
What may seem 'fantastic' on a closed-course mileathon at 20-mph may be a non-starter in the 'real' world of driving,at 'real' velocities.