Saturday, December 06, 2014

F-22: You're too fast, you're under arrest

By Marlene Gantt

(Editor’s note: Ms. Gantt’s son, Brad Gantt, airfield maintenance supervisor for the Quad City International Airport, contributed significantly to this column)

 

A stealthy fighter with an ominous presence flew over the airshow crowds at the Davenport Municipal airport last summer.  With a price tag more than $150 million, its aerial abilities are mind boggling.

The demonstration amazed those of us who didn’t know that a vectored thrust jet could do what we thought was impossible.

The F-22 was the main feature of the show and the topic of last week’s column. This week, however, is about one piece of equipment deployed by a team behind the scenes to provide safety measures for this incredible aircraft -- the Mobile Aircraft Arresting System or “MAAS.”

On Jan. 18, 1911, Eugene Ely, flying his Curtiss Model D biplane performed the first aircraft landing aboard a ship. The ship was the USS Pennsylvania, an armored cruiser.

Early aircraft were not usually designed with brakes and the Curtiss was no exception  Ely attached hooks to his biplane. He then used the first known version of an aircraft arresting system and landed on a 119 foot wooden platform with 22 ropes across it and secured by sandbags, according to the book, “Chronicle of Aviation,” published by Jacques Legrand.

This was just eight years after the Wright Brother’s historic first powered flight. Today’s aircraft arresting systems are a little more advanced.

Weeks before the anticipated arrival of a pair of Raptors coming to our air show, a team of engineers was onsite to determine a suitable location for a MAAS. It would be used by the F-22 pilot in the event of an emergency or problems with the aircraft.

Of course the F-22 is fast and sleek but is equipped with brakes unlike early aircraft designs. Early aircraft were slow and usually had large fields to land in. They also often had spoke wheels reminiscent of bicycles. I wonder how much that was influenced by Orville and Wilbur Wright’s background as bicycle makers?

This didn’t create much need early on for brakes or systems to stop quickly.

Today, safety is always a top priority and in-flight system failures can result in emergency landings.  Stopping quickly with an arresting system protects the pilot and aircraft.

All of us have seen footage of planes landing on aircraft carriers where a cable or net is raised above the ship deck. Aircraft drop a tail hook down to catch it and stop quickly, often in just a few hundred feet. Many people may not realize that land airports throughout the world have permanently installed systems that do the same thing as those on these massive aircraft carriers. These permanent installations are called BAK 12/14 systems. Even Eugene Ely’s feat of landing with ropes and sandbags on a ship was first tested on shore.

The BAK 12/14 is comprised of a pair of arresting engines, one on each side of the runway in below ground vaults, and a “pendant” (thick braided steel cable) stretched across the runway. Slotted rubber arms are used to raise and lower the cable into a track installed in the pavement. The slots allow the cable to be pulled free by the landing aircraft.

The arresting engines then allow an approximately 10 wide “tape” to spool out while providing braking force capable of stopping a fighter jet traveling at 150 mph in under 1,200 feet. Obviously this is no ordinary tape, and yes it is even stronger than duct tape.

No airports in our area have need for a permanently installed arresting system. Enter the MAAS or Mobile Aircraft Arresting System. Like the permanent system, a MAAS uses a cable and tapes attached to arresting engines on each side of the runway. Unlike the BAK 12/14, it is temporarily installed above ground wherever and whenever the mission requires it.  For our airshow, the mission required one nearby.  Since the Davenport airport runways are too short for normal fighter jet operations, each year Air Force fighter teams use the Quad City International Airport in Moline as their operating base for our air show.

The two MAAS arresting engines weigh over 20,000 pounds. each. Each engine is secured along the runway edges with a minimum of 19 anchors similar to tent stakes in shape. But these are no ordinary stakes. These are 4-inch diameter aluminum and over four feet long. Each takes as much as 10,000 pounds of force to drive into the ground and are interlinked with a series of brackets to form a matrix of stakes on one side. If the cable is to be used bi-directionally then 31 stakes are used, each precisely driven at an angle to safely stop a 40,000-pound aircraft traveling at 150 mph. How many sandbags would it take to do that?

Installing a MAAS is no small task. The FAA must approve any MAAS installation at commercial service airports. The Air Force 201st Red Horse Squadron team arrived a week before the show and spent several days installing the unit on the only runway available at the time.

Unfortunately, after reviewing the installation the Air Force rejected this location and advised they needed a longer runway for the MAAS or the aircraft could not perform at the show. The preferred runway was still occupied by construction workers completing an airport project.


Marlene Gantt of Port Byron is a retired Rock Island school teacher.
 
Source: http://www.qconline.com/editorials

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