Author Topic: Why don’t today’s fighters have narrow waists?  (Read 349 times)

0 Members and 1 Guest are viewing this topic.

SPQR

  • Guest
Why don’t today’s fighters have narrow waists?
« on: December 13, 2013, 12:59:33 AM »
By Paul Hoversten
Mark Mallari of Manila, the Philippines, writes in with a question on supersonic flight: “Whatever happened to the Whitcomb area rule that revolutionized the design of supersonic aircraft? A supersonic aircraft’s fuselage was supposed to narrow down at the widest point of the wings, in order to maintain a constant overall cross-sectional area for less drag.

“Early supersonics such as the wasp-waisted F-106 and B-58 Hustler are exemplars of this, but modern fighters such as the Eurofighter Typhoon seem to have no need for area ruling in their design,” he writes.

Mallari points out that the rule’s namesake, aerospace engineer Richard Whitcomb, who discovered it in 1952 while working at the National Advisory Committee for Aeronautics, won the Collier Trophy “so it must not be something insignificant!”

The answer is, the area rule only mattered to designers of early fighters, who struggled with underpowered jet engines. In the 1950s, Convair and Grumman were concerned with the phenomenon known as transonic drag rise, in which the air “bunches up” around the fuselage at the wings, causing drag, which decreases aircraft performance. One way to smooth out the bunching was to “pinch” the shape of the fuselage so the air could flow more evenly around the wings.

“Without area ruling, the wing acts like a speed bump. The air just doesn’t have a place to go,” says Cam Martin, external affairs officer at NASA’s Dryden Flight Research Center in California.

Convair used the area rule in designing the F-102 Delta Dagger, the F-106 Delta Dart, and the B-58, while Grumman incorporated it into its F9F/F-11F Tiger.

With the advent of more powerful jet engines, “drag rise become less of a factor because you have enough power to bulldoze through it,” says Martin. That’s why designers of the Typhoon or the Lockheed Martin F-35 Lightning II don’t give a moment’s thought to drag rise; engines on those aircraft have plenty of brute force to overcome it.

In the NASA volume From Engineering Science to Big Science, Lane Wallace writes that Whitcomb’s discovery “was just an idea. It may have been developed at a NACA laboratory, but it was not up to NACA to apply it. In order for the innovation to have any impact at all, industry had to agree to use it, which is not always as simple a process as it might seem. …The advantages offered by the innovation were the same; the costs of implementing it differed.”

The area rule, says Martin, is simply “a tool or a technique,” one that has little relevance to today’s military jets.

http://www.airspacemag.com/need-to-know/Need-to-Know-Why-Dont-Todays-Fighters-Have-Narrow-Waists-199886821.html?story=fullstory

Offline EC

  • Shanghaied Editor
  • Hero Member
  • ****
  • Posts: 23,836
  • Cats rule. Dogs drool.
Re: Why don’t today’s fighters have narrow waists?
« Reply #1 on: December 13, 2013, 03:09:59 AM »
Quote
The area rule, says Martin, is simply “a tool or a technique,” one that has little relevance to today’s military jets.

Now on that, I disagree.

Sure, modern engines have more than enough thrust to shove a brick through the air, but utilizing the Whitcomb rule would increase efficiency. That translates directly into more speed, greater range or a greater loadout for the same fuel cost, as well as less strain on the engines.
The universe doesn't hate you. Unless your name is Tsutomu Yamaguchi

Avatar courtesy of Oceander

I've got a website now: Smoke and Ink

SPQR

  • Guest
Re: Why don’t today’s fighters have narrow waists?
« Reply #2 on: December 13, 2013, 03:11:08 AM »
Now on that, I disagree.

Sure, modern engines have more than enough thrust to shove a brick through the air, but utilizing the Whitcomb rule would increase efficiency. That translates directly into more speed, greater range or a greater loadout for the same fuel cost, as well as less strain on the engines.

I agree

Offline EC

  • Shanghaied Editor
  • Hero Member
  • ****
  • Posts: 23,836
  • Cats rule. Dogs drool.
Re: Why don’t today’s fighters have narrow waists?
« Reply #3 on: December 13, 2013, 03:17:38 AM »
The only downside is fitting in the internals and a slight loss in structural strength during high G turns, which can be more than made up for by using higher spec alloys for the airframe, and moving towards a triple layer armor like the Ka-50 has.

The universe doesn't hate you. Unless your name is Tsutomu Yamaguchi

Avatar courtesy of Oceander

I've got a website now: Smoke and Ink

SPQR

  • Guest
Re: Why don’t today’s fighters have narrow waists?
« Reply #4 on: December 13, 2013, 03:19:06 AM »
The only downside is fitting in the internals and a slight loss in structural strength during high G turns, which can be more than made up for by using higher spec alloys for the airframe, and moving towards a triple layer armor like the Ka-50 has.

I really like the designs of those planes. Those were the good ole days.

Offline EC

  • Shanghaied Editor
  • Hero Member
  • ****
  • Posts: 23,836
  • Cats rule. Dogs drool.
Re: Why don’t today’s fighters have narrow waists?
« Reply #5 on: December 13, 2013, 03:21:53 AM »
They did have a grace that is rarely seen in the modern jets.  :laugh:

Then again, my baby was ugly as sin  :laugh: Once described her as the result of a grasshopper having it's way with a very surprised 747!  :whistle:
The universe doesn't hate you. Unless your name is Tsutomu Yamaguchi

Avatar courtesy of Oceander

I've got a website now: Smoke and Ink

SPQR

  • Guest
Re: Why don’t today’s fighters have narrow waists?
« Reply #6 on: December 13, 2013, 03:29:07 AM »
They did have a grace that is rarely seen in the modern jets.  :laugh:

Then again, my baby was ugly as sin  :laugh: Once described her as the result of a grasshopper having it's way with a very surprised 747!  :whistle:

In the case of the Delta Dart they needed a plane that could intercept Bear Bombers.


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf