ACES 5 Ejection Seat Offers A Safe Escape

Nov 9, 2015 - 3:35 PM

UTC Aerospace Systems (UTAS, Stand 1140) is exhibiting its latest ejection seat, incorporating significant safety and cost-saving upgrades, according to the company.

The Advanced Concept Ejection Seat 5, or ACES 5, is available for new combat and fast training aircraft programs in the U.S. and elsewhere. UTAS has also offered the U.S. Air Force a retrofit kit for the thousands of ACES II seats in service.

“Unlike the ACES II, which has a single monocoque structure, the ACES 5 is modular,” Jim Patch, senior program manager for the new seat, told AIN. This feature avoids the need to remove aircraft canopies or hatches when the seat has to be removed for maintenance, he explained. The new structure also improves access for changing service-life items, and the seat bucket can be separately and easily removed, if required, to make it easier to search for foreign objects dropped in the cockpit.

“The ACES 5 is the most stable seat in the world,” Patch claimed. It features faster deployment of the drogue parachute to reduce yaw, and a new GR7000 main recovery parachute that reduces the rate of descent and oscillation. Patch said this was significant, because 43 percent of ejection-related injuries occur during the landing phase.

The seat also features an active pitch stabilization system–the rocket is gyro-stabilized–to compensate for the pitch changes caused by the varying weights of pilots, and by aerodynamic effects.

Restraining fast jet pilots during an ejection has become a major concern in recent years. The introduction of helmet-mounted sights and night vision goggles, with their added mass, has increased the risk of head and neck injuries. The death of an F-16 pilot who ejected from an F-16 on an ACES 2 seat in 2013 was attributed to this cause.

The F-35 Joint Program Office (JPO) has temporarily grounded lighter-weight pilots from flying the Lightning II because of the potential for injury in a low-speed ejection. The F-35 is fitted with the US16E ejection seat from rival maker Martin Baker. The British company designed a trio of airbags that inflate in a two-stage process, as a head and neck restraint system. JPO chief Lt. General Chris Bogdan told Congress last month that three “fixes” are being pursued: a lighter helmet, a slight delay in the parachute opening, and additional head support.

Patch says that the ACES 5 seat solves this problem with a “passive” head and neck protection system that does not require lanyards, tethers or inflatables. A framework unlocks and follows the pilot’s head as it is forced down by g-forces during an ejection. It also prevents the head from “snapping” left or right from wind blast. The ejectee’s arms and legs are also restrained by passive means. Arm restraints on the seat are deployed by a cord attached to the cockpit floor. A pilot’s legs are pulled inside the fences on the side of the seat by similar passive means, as the seat rises.

In the ACES 5, UTAS has retained the same cartridge-actuated devices (CAD) and propellant-actuated devices (PAD) from the ACES II. This is proven technology, and the U.S. government procures the devices competitively, Patch noted.

UTAS claims that the CKU-5 catapult rocket provides the softest ride available, with a spinal injury rate of only 1 percent. Since being introduced in 1978, the ACES II has saved more than 630 lives. It is used on the A-10, F-15, F-16, F-22, B-1 and B-2 aircraft.

The ACES 5 seat has been rigorously tested to validate performance and reliability, according to the company. Potential applications include the U.S. Air Force LRS-B and T-X programs.