Design a plane

[Richard]

Some time ago did Ed Fred inquire of how to reduce form drag. I sought to find that thread but got side tracked.

Not remembering if I suggested such at the time but the answer could be found in everything from NASA to Piper STCs.

The Aztec was improved* by a kit (circa 1966) which featured an elongated nose.

Every high velocity NASA airframe featured an elongated nose with stub wings.

The answer to Ed Fred's original question was to elongate the nose towards a needle penetration of the air.


*20 kts faster, 3 gph reduction per 1967 Piper advertisement.

What improvement to form drag can the reader suggest?

EDIT: CAR 3 or other govt rule shall not be a consideration.

 

[Richard]

My suggestion is not to the frontal area but to the aft sections. A longer empennage would allow a smaller tail section which includes a smaller vert. fin and rudder. W*A*M

 

[Richard]

Since we are talking of fluid dynamics, it may be of interest that the well reputed boat designer L. F. Herreshoff spoke of 2.78:1 as being the ideal beam to length ratio for a 'fast hull'.

 

[Henning]

Since we are talking of fluid dynamics, it may be of interest that the well reputed boat designer L. F. Herreshoff spoke of 2.78:1 as being the ideal beam to length ratio for a 'fast hull'.

He was wrong. 7:1 or narrower. 2.78:1 works well for a planing hull, but when one refers to a 'fast hull' one is normally referring to a displacement hull.

7:1 is the magic number where you start piercing your bow wave. The bow wave now rolls to side rather than being thrown forward, and you lose your 1.34*sqrt Waterline length wave trap speed restriction. You also improve the heck out of your fuel economy. There are ways to trick the waterline length with bulbous bows and pressure/Vortices generator on the stern, but you're still like 6.2:1.

We've learned a lot since Herreshoff.

 

[ClimbnSink]

He was wrong. 7:1 or narrower. 2.78:1 works well for a planing hull, but when one refers to a 'fast hull' one is normally referring to a displacement hull.

7:1 is the magic number where you start piercing your bow wave. The bow wave now rolls to side rather than being thrown forward, and you lose your 1.34*sqrt Waterline length wave trap speed restriction. You also improve the heck out of your fuel economy. There are ways to trick the waterline length with bulbous bows and pressure/Vortices generator on the stern, but you're still like 6.2:1.

We've learned a lot since Herreshoff.

Or never noticed. The Eskimos had wave piercing bows on their kayaks.

 

[Henning]

Or never noticed. The Eskimos had wave piercing bows on their kayaks.

Really, it's only become feasible on mid sized mono hulls in the last few years with gyro stabilization. Most Navy Man o Wars are closer to 10:1.