Optimum nose shape

[Otto]

Remember about 10 years ago when that Navy P3 Orion was hit by the hotrodding Chinese fighter plane off the China coast?

If nose shape is insignificant and the afterbody is what really defines drag, then the P3 should have flown just as fast and well after its nose cone was knocked off as it did before. After all, the fuselage and afterbody was not changed in any way, but the radome/nose cone was knocked off the P3.

Well, that thing was an absolute ***** to keep airborne due to buggered flow and uber-high drag. Speed dropped radically, as did control and stability. I'm sure fuel consumption spiked, even at much lower speed.

Maybe it's time to dispense with the old wives' tale that nose shape is relatively unimportant. Otherwise, we're saying Porsche, Ferrari, Nascar, and Mother Nature are all flat wrong. If nose shape were relatively insignificant, largemouth bass could swim as fast as tuna. Can they?

Maybe, like Heinrich Hertel, it's a good idea to look to Mother Nature and see her empirical handiwork of the past 200 million years. I bet Mom could give us a few pointers on cooling drag, re-introduction of spent cooling air back into the slipstream, nose and afterbody shape, etc..

[cujet]

Interesting point about the P3. I'll have to look into that.

I'll have to counter that with banner towing aircraft that remove the entire front cowl for engine cooling. And, they fly just fine, and often just as fast. I was involved with this in a past life and almost forgot about it.

[cujet]

From Wiki: ""On the third pass, it collided with the surveillance aircraft. The J-8 broke into two pieces, while the EP-3's radome detached completely and its No. 1 (outer left) propeller was severely damaged. Airspeed and altitude data were lost, the aircraft depressurized, and an antenna became wrapped around the tailplane. The J-8's tail fin struck the EP-3's left aileron forcing it fully upright, and causing the U.S. plane to roll to the left at 3-4 times its normal maximum rate.[6]

Area of the collision in the South China Sea

The impact sent the EP-3 into a 30° dive at a bank angle of 130°, almost inverted. It dropped 8,000 feet (2,400 m) in 30 seconds, and fell another 6,000 feet (1,800 m) before the pilot, Lt. Shane Osborn, got the EP-3's wings level and the nose up.""

[aerohead]

In automotive applications,the aft-body performance is governed by quality flow arriving from the fore-body.
The FLUIDs professor/textbook writers say that below 250 mph,a semispherical nose is plenty good and to concentrate on the aft-body for drag reduction.
The add-on nose to the CRX,which is in the direction of where you're going with the Porsche,made no measurable difference at 100 mph.
I don't think it is physically possible for any nose mod,regardless of how 'slick' it is,to make a significant showing at the pump,driving at posted speed limits.I do think that if you are going to modify the back of the car,then a really clean nose will help in that context.
With respect to the Orion,I don't know if that's germane to what we do.
When at DaNang,an Airman -of-the-Month won a back-seat ride in an F-4 Phantom.An avionics guy had not properly fastened the nose radome and they lost the whole thing in flight,causing the radar antennae to be shredded away by the airstream.The pilot had no problem with flight stability,however a hydraulic line had been severed,with time the plane would become un-fliable,and with the fluid all over the windscreen he had no forward vision.
They talked them down okay.The pilot was unshaken,the 'Airman' had to change his clothes.
And the thing about fish,they're governed more by skin friction,with the 833 times more dense water,than they are with profile drag,of which neither of the fish possess.
The Bluefin has the ' lowest' Frontal Cd of fish but is not the fastest fish.That title goes to the sailfish,clocked at over 60-mph.And for 'sustained' velocity,the bottlenose dolphin is given the credit,at around 30-mph and bursts to 45.
If memory serves me,Hertel gives the lowest frontal Cd of any measured 'structure' to the gentoo penguin.

[aerohead]

Here's a graphic for the drag breakdown measured for the Ahmed body model,researched, probably by half a dozen investigators now.
For the zero slant back configuration you can see that the entire nose drag constitutes less than 6% of overall drag,while the base drag,due to the turbulent wake is over 70% of the overall drag.This is why Hucho repeatedly emphasizes the importance of a vehicles aft-body.
We can't do anything about skin friction,so we basically ignore it.If it were an airplane we'd obsess over it.

[kach22i]

Originally Posted by Frank Lee

944s are beautiful! Don't geek it out!

I agree.

Just put some conveyor belt material attached to the lower valance and make a zero clearance chin spoiler like the track guys do.

Drive around with the windows rolled up if you want maximum aerodynamics.

Similar:
Yellow Bird Chin Spoiler - Pelican Parts Technical BBS




More similar images:
http://forums.pelicanparts.com/911-9...t-spoiler.html


Better than this:
http://speedconceptsonline.com/buysp...ler-lower.html


EDIT: perhaps a polycarbonate rear glass to save weight?

http://forums.pelicanparts.com/porsc...ml#post8976924

[freebeard]

^^^^??????

That picture raises a lot of questions. Not least is the scale, I'd guess 1/10th. What's the cable connector hanging under the left front? What's the translucent overlay over the flip-flop paint?

The Porsche air-dam is nicely done. The fasteners are in the middle of the strip instead of the top, so it holds it's shape better?