Reply To: Golf ball concept

Forums Pellets, Projectiles, Slugs, & Ammo Golf ball concept Reply To: Golf ball concept



“Mousefart”I’m thinking that if the principle held for a pellet then it would for aircraft also, and I assure you that in my 40+ years in aviation I’ve never seen the nose of an aircraft dimpled. Ever. 


The answer is because there are different types of drag. The two types relavent here are base drag and skin friction drag. Base drag is the drag created when airflow separates from a body creating a low pressure area behind the body. Skin friction drag is the drag generated by airflow rubbing against the body. Golf balls take advantage of scallops or dimples to create small vortices that energize the flow, which keep it attached to the body longer. This energized flow creates more skin friction drag, but reduces base drag. In the case of a round body, like a golf ball, the base drag is so much bigger than the skin friction drag, that even though the dimples increased the friction drag, they reduced the base drag so much that the net effect is a reduction in total drag.

Airplanes used much more streamlined shapes, so they already have really low base drag. If airplanes use dimples to energize flow, they will increase skin friction drag, but won’t gain much in terms of their already low base drag. So the net effect will be an increase in total drag.

You might think that I just pulled this question out of the air just to post something but I have not.
I have actually done some research on the subject bullets and pellets do not have the length to size ratio that a plane does (at least not until you start talking about really heavy grain big bore rounds) this cushion of air that the dimples create could be an alternative to the flare tail that is currently being used to stabilize pellets or at least be used to reduce the needed tail drag and therefor increase its distance to accuracy ratio.