The long pointed tail only matters if the flow remains attached to the contracting body. If you can maintain that flow attachment, the pointy tail makes a big difference. If the flow separates, there is a big drag increase that will be proportional to the size of the separated region. When this happens, it makes little difference if you cut off and remove any part of the body that is within this separated flow region.I need you guys to explain something to me. On one hand for any object moving through the liquid ,shape is very important to reduce drag. we know that shape of the front part of this object is equally important as shape of the back side.
On other hand I am hearing this explanation that airflow on the back side of abruptly shaped object will form turbulent Triangle that will work like a bearing and this void will be naturally filled. So, we should stop worrying about building anything for this area?
I believe Peter Garrison at one point was telling me that all this fancy looking Spinners that you guys using on canards complete nonsense.
I also see how they shape fuselage on icon A5 right before propeller. They must have the same logic as far as airflow concern.
when we standing on the bridge and looking down we can see how water is moving around concrete columns. You can clearly see still water forming that kind of area that’s really not moving at all and acting like filler.
so, do I see it correctly? In certain area like prop spinner for pusher or backside of fuselage after body doesn’t need to be perfect?
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Cars have a rear window and a surface bump at the roof to window transition that tends to separate the flow. Designers found that if the rear window transition did not drop too fast, the flow could remain attached over the transition bump and recover more of the car body's form drag than a traditional rear window that drops down to trunk level. This is where the Honda CRX got it's look. Even today, cars that focus on aerodynamics tend to look similar to compact station wagons with a mildly sloping rear roofline that cuts off abruptly. The goal is to contract the flow as much as possible before it separates from the body. At some point size constraints of the car dictate that the car can't be any longer than 'X', so you terminate it with a flat end and let the flow separate (i.e. - cut your losses, literally).
I hope this explanation helps.