F-100 Super Sabre Jet
December 1953 Popular Science

June 1941 Popular Science
June 1941 Science Popular Science - RF Cafe[Table of Contents]

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F-100 Super Sabre Jet

This is the Fastest Fighter in the World

More jet power, more sweep of wing, and a low-drag fuselage make the F-100 the swiftest fighter plane in our air arsenal.

With the F-100 Super Sabre jet now in production, the Air Force gets a truly supersonic weapon.

By Herbert O. Johansen

The "Y" has been taken off the North American YF-100 jet fighter.

That means it is no longer experimental, that the U. S. Air Force now has in production the world's fastest fighter - one that can sustain supersonic speed in level flight.

We - and the British, and probably the Russians - have for some time had jets that were capable of faster-than-sound flight in dives accompanied by the sensational sonic bangs or, perhaps, in brief supersonic bursts boosted by jet afterburner. But the F-100 is a new breed of plane-it is supersonic in level flight. It is built and powered for super-sonic flight as routine operation - not just as a stunt or an all-out record-setting, headline-making effort.

A Whole Supersonic Air Force

The F-100 is a milestone, marking the coming-of-age of the jet age - the first in a series of new faster-than-sound fighting airplanes. Among these are the Air Force's McDonnell YF-101 twin-jet Voodoo long-range bomber escort; the Convair YF-102 delta-wing fighter; Republic's XF-103 research fighter and YF-105 fighter-bomber; Lockheed's YF-104; and for the Navy, the Douglas XF4D-1 Sky-ray delta-wing fighter (which in recent tests flew faster than 760 m.p.h.), the Grumman XF10F-1 Jaguar variable-sweep-wing fighter, and the McDonnell XF3H-1 Demon.

Some of these newcomers have been flown, some are being built and others are still on paper. Some may not get into production as better and faster models develop from lessons learned. But as the Ys - for-experimental drop off, our military air forces become truly supersonic. A daytime fighter, the F-100 is a gun platform. Its main mission is to destroy enemy fighters over enemy territory to give us not only air superiority but the control of the air we would need during those last critical miles as an A-bomber neared its target. For that job it must be able not only to fly high and fast, but for long distances, which means great loads of fuel. So it is big; and, since it is big, it can carry under-wing loads of bombs or rockets for a secondary mission as a low-level air-ground attack weapon. Such external loads would necessarily slow the plane down, but once the load was dropped, the F-100 could fight its way back to base at supersonic speeds.

Big Intake at nose lets F-100 gulp vast amount of air needed for supersonic speed.

Thick, straight wing, stubby nose, protruding guns, bulging canopy of World War II Republic Thunderbolt would have acted as drag brakes at speeds that jet makes possible.

Jet Power made its U.S. debut in this Bell P-59 Airacomet that first flew in October 1943. Absence of propeller enabled designers to clean up the fuselage.

More Wing Sweep Increases Speed

Although it is an evolution of the F-86 Sabrejet that has broken many speed records and made aerial-combat history over MIG Alley in Korea, the F-100 Super Sabre is a new plane. That it is supersonic would mean that it can fly faster than sound at all altitudes, which varies from 660 miles an hour at a combat altitude of 40,000 feet to 762 miles at sea level. Bigger than the F-86 fighter, the F-100 is 45 feet long and weighs more than 20,000 pounds.

Most notable change is in the wing. Where the latest F-86 has 35-degree sweep, the F-100 has a thinner wing that is swept back 45 degrees. The tail also has more sweep back.

Power behind the F-100 is a new design in jet engines, the split-compressor J-57, claimed by the manufacturer, Pratt & Whitney, to be the most powerful production engine in the world. With it, the Super Sabre is reported to have more than 10,000 pounds of thrust and about 15,000 pounds with afterburner (the F-86D has 7,600 pounds of thrust with afterburner).

First Operational Jet Fighter, the Lockheed F-80 Shooting Star, met Red MIGs in combat in Korea. Although the wing is still straight, it is much thinner for less drag.

As More Powerful Jet Engines enabled planes to nudge the speed of sound, designers were forced to sweep back the wings, as in this North American F-86 Sabrejet.

Split-compressor. or twin-spool, means that an engine has two compressors in series, each driven by a separate turbine. There are two shafts with no mechanical connection between the two turbines. The first (low-pressure) compressor feeds the second (high-pressure) compressor. The result is a higher range of compression ratios than can be obtained on a single-shaft compressor.

Jet Speeds Bring New Designs

Among the advantages of the split-compressor are lower fuel consumption for range or higher power output for speed and maneuverability; the elimination of "surging," or back-flow, problems in the thin air at high altitudes; easier starting, and fast acceleration.

As jet engines became more powerful, new fuselages and wings were designed around the engine, and the early Lockheed F-80 Shooting Star and the Republic F-84 Thunderjet were born. Wings were still straight, but streamlining sent speeds up 100 and more miles an hour. Then jet-engine power went up and greater speeds forced the designers to go to thinner and swept-back wings to delay drag and the turbulence that wings run into at transonic speeds.

Ever-increasing jet speeds have posed other problems. When our first jet plane, the experimental Bell P-59 Airacomet, was announced in 1944, the Air Force thought it had the makings of a simple, lightweight fighter that would burn almost anything as fuel. Kerosene was it - at first. Disillusionment came fast-as fast as speeds increased. Jet engines had to abandon kerosene for gasoline, and today that has had to be replaced by special, high-grade JP fuels.

Principle of split-compressor jet engine that powers the F-100 is shown in drawing above.

Then there was the matter of weight. After all, a jet plane is only a shell built around a blowtorch. Nothing complex about that. But again, greater speeds and more powerful engines changed the picture - there was the pilot to consider.

Pressure suits enabled him to take the terrific Gs at jet speeds, but he must also fly and fight at high altitudes to take advantage of lower fuel consumption. That meant a pressurized cockpit and an improved oxygen system to keep him alive should the pressurization fail.

Speed of Sound varies with altitude. Critical speed area is the transonic where the air-frame runs into violent turbulences. At supersonic speeds air becomes smooth again.

Heat created by friction necessitated refrigeration of the cockpit, and because it is bitter-cold up there, heaters had to be provided to prevent guns from freezing. Add to this an ejection seat for the pilot in case of bail-out, computing radar gunsights and power controls, and you have what is mildly called "complexity."

Now that the Air Force has hit the supersonic, the question arises, "How much faster will we fly?"

Top fighter men in both the Navy and the Air Force say, "At least 100 miles an hour faster than the enemy."

 

 

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