WHAT? AN F-86 AT 70,000 FEET!

by TOM GILL

In 1959, I was a really `wet behind the ears" Flight Test engineer working for North American. I'd just jumped the fence from Lockheed because NAA had all kinds of aircraft and missile work that looked like it would stretch on forever.

NAA decided to make an attempt to sell the F-86 to Japan as an interceptor. However, at that time there were many more advanced aircraft available like the F-100, F-104, and F-4, which was almost ready to be-come operational. The F-86 would need a little help to play with the big boys.

So, a Rocketdyne AR-2 engine was fitted to the under-side of an F-86F. The installation didn't appear to be a `clean' assembly. In fact, one of the engineers likened it to a 1912 bathtub! Wing tanks were added to carry hydrogen peroxide as an oxidizer for JP-4. The airplane was delivered to NAA Flight Test at Palmdale.

The rocket was small. I couldn't get my hand inside the nozzle. I don't recall the weight of the rocket, but it wasn't much. The rocket was about 2 1/2 feet long, and less than 1 1/2 feet high. But WOW! Over 5000 lbs. of thrust at any altitude!

We were trained on handling the hydrogen peroxide. It wasn't the kind you find at the drug store. The concentration was 90%, and very unstable. All of the plumbing, including the drop tanks, was passivated stainless steel, with Teflon seals. Several demonstrations were made to illustrate the instability. The instructor put two drops on a man's boot, then went on with the training session. After a few moments, the boot was on fire!

Another demonstration was made after dark on the flight line. The wind was coming in off the snowy Tehachapi's at about 25 knots. And the temperature was about 40 - not exactly the best conditions to light a fire without a match. About an inch of JP-4 was placed in a drip pan. Then a shot glass full of peroxide was placed on a board over the pan. A long string was used to upset the shot glass into the JP. But when the string was pulled nothing happened.

Someone suggested they repeat the demo except use a PINT of peroxide instead of a shot glass full. The instructors limited the demo to no more than 2 ounces. The string was pulled and literally everything disappeared, including the board, in a cloud of smoke and debris.

A special ground run-up area was prepared which included all the necessary tie downs as well as safety equipment to handle the fuel mix. Lots of water was available for washing down the area as well as a personel shower that was something to behold.

Engine runs were conducted and the airplane was readied for testing. During the engine run-ups, it was possible to see "mach diamonds" in the rocket exhaust. I counted as many as 7 diamonds during one of the runs. And plenty of noise too! Jim Brooks was assigned to the project as test pilot. During the initial flights, we tried to determine the best climb schedule so the design flight profile could be con-firmed. Brooks' comments - "You could sure surprise an enemy by falling out of the sky from above them in an F-86!" Apparently, the flight profile after burnout was pretty much ballistic. Service ceiling on the J47 engine was limited to about 28,000 feet. (Hydrogen Per-oxide is much heavier than JP-4, so our gross weight was way up, as was the drag due to the `1912 bath tub'.

Typical flight profile was to climb near the service ceiling on jet power, then light the rocket. There was enough fuel in the wing tanks to burn the rocket for 3 minutes. But in those 3 minutes, you went from 28,000 to 70,000 feet. Beyond that, it was pretty much a free fall.

A group of four Japanese Air Self Defense Force colonels visited the plant for the demo flights. The one that flew the test flight was almost able to match the Jim Brooks' efforts, and if I recall correctly, he actually did better the best flight profile on one run.

The maintenance officer was one of the most curious men I have ever known. He carried a note pad all of the time, sketching everything he saw - door hinges, latches, components, and anything else he saw. He did create amusement for all of us one day. In the engine run-up area, the personnel shower became a focus of his attention. This was a good shower with at least four speay nozzles in the top. In the center was a prominent break-over bar. When it was pushed aside, lots of water came from every direction.

The Japanese officer became very interested in the shower and began examining it very closely, too closely. Upon noting his interest in the device, the other officers were alerted to his actions. He disappointed no one, especially the other Japanese who laughed the loudest when he was the wettest.

Despite the increase in performance, the Japanese did not buy the rocket Sabre, opting instead for the Lockheed F-104J. But without a doubt, that Sabre was impressive!

There were other rocket-assisted F-86s. During the Korean War, at least three Sabres had triple RATO bottles mounted internally under the J47. They were combat tested by the pilots of the 4th FIG in 1952. Cliff Jolley and Karl Dittmer both flew the modified Sabres in combat. Both said the installation worked well for acceleration against the MiG, but then you were hauling around about 600 extra pounds after the rockets burned out, which threw the aircraft CG out of whack.

In June 1956, Air Force authorized North American to install an Aerojet rocket engine in a large pod under the fuselage. At this time we know very little about the flight tests of this airplane.


No portion of this article may be used or reprinted without permission from the President of the F-86 Sabre Pilots Association or the editor of Sabre Jet Classics magazine.


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