"BUFFALO HUNTERS"

CH-3C/E MARS Recovery Aircraft.

63-9687, 63-9690,

64-14223, 64-14226, 64-14228,

65-5690, 65-5696, 65-12788, 65-12790

CH-3E 65-12790 ON DISPLAY HILL AFB MUSEUM

The 432nd Drone Group operated out of Davis-Monthan utilizing the CH-3E MARS equipped aircraft.  The MARS mission was also utilized during the war in Southeast Asia.  Below is the link to some pictures taken at the March 1977 Open House at Davis-Monthan.

The 6514th Test Squadron of the Air Force Systems Command was activated at Hill AFB on 1 July 1973 as a detachment of the Air Force Flight Test Center (AFFTC) at Edwards AFB, California. The unit was responsible for the testing of remotely-piloted vehicles over the Utah Test and Training Range. Below are links to words about the 6514th and a picture of the CH-3E, pictures of the NCH-53A and some words from the Sikorsky Tech Rep that was assigned and was instrumental in the unit getting the H-53.

MEMORABLE MISSION OF HARVEY METZLER

I was assigned working MARS at DaNang in 68. I Flew 59 missions, 1/2 of them were in NVN. Yes there are plenty of stories to share. One quick one. The Bug aborted early, went into the chutes just off of Tiger Island NVN. It became a race to try and get it before it went into the water. We were at orbit 10K feet and many miles away. We went into a high speed decent with our poles deployed (scary) , max speed should be 50kts. We did get up over 70. The catch was done with the bug about 20 ft from the water. Then with it half way to stow position the winch stopped. We flew for the next hour with the bug over 100 feet below us. What I never can forget was the radio on guard calling "Bandits" heading south from Squid and Oyster, the 2 biggest MIG bases. But we made it back and delivered the Bug intact. We always flew twice a day on these. Sometimes they went clean and neat.

PERSONAL EXPERIENCE FROM JIM BURNS

I was part of a crew picking up a drone recovery bird from Edwards, AFB and ferrying it to Tyndall (I think this was in 1972) and got to make two MARS flights. The above picture shows the winch box mounted on the cabin floor and the 'snatch' poles that were stuck out the rear of the cabin. Here's what else I think I remember about the system. The winch box was mounted over a hole in the cabin floor and the recovery cable was strung along the bottom of the hull and attached by a break away rope or string or something to the end of the poles. There was a grappling hook on the end of the cable. In flight the poles were extended out and down from the back of the cabin and the snatch cable and grappling hook trailed below the chopper, strung between the two poles. The pilot positioned himself above the drone altitude and when the drone's recovery main chute and drag chute deployed the H-3 would dive down from above it and fly right over the top of the chute where the trailing grappling hook would snag the chute and capture the drone. Once the drone had been 'snagged' and stabilized below the chopper, then the winch cable would be reeled in to bring the drone to about 20 feet below the chopper. Then it was flown to a soft landing and released by the CH-3.

The drones weighed between 2,000 to 2,500 pounds and I don't take a lot of imagination to know how the CH-3 might react when it's diving on a drone at about 100 knots ,or so, and it snags into a couple thousand pounds of weight swinging like a pendulum at the end of a very long cable. Thank goodness for the hydraulics that slowed down the impact of the snag. I would imagine that if the cable was fixed without a chance to reel out and slow down the grab that it would yank the chopper out of the sky.

My memory of the these missions is of the steep dive to snag the chute, then the sudden stop once the drone, with all it's extra weight was caught, then the H-3 beginning to fly again, then the winch procedures. Maybe it was because I was more or less a 'tourist' on these two missions, but this just seemed like a hell of a way to make a living!!!.

COMMENTS FROM BOB BUTTERFIELD

Jim B, your description of a drone recovery is correct. To clarify further, the rope that was connected to the cable was attached to the poles by duct tape (pretty Hi-tech). It was a rigging that had three hooks, one at the end of each pole and a "Flying Hook" that hung in between.  When contact was made with the drag chute, the hooks and rope pulled free of the poles, the winch fed out cable and hydraulics slowed the feed out.  That was the moment that you heard a definite "Rotor Droop" as the sudden weight slowed the rotors and there was a rapid decent. Not a comforting sound.  Once the drone was reeled in and stowed beneath the H-3, it was a pretty uneventful trip to the drop zone, where the drone was lowered to the ground and the rope was cut by the WO. Other than the few moments after a "Capture", the missions were fun. We always used two choppers on a recovery mission just in case the Primary Bird missed the drag chute or had a "Tear Through".

RECOVERY SYSTEM

INFO COURTESY OF DAVE MATTHEWS~PROVIDED BY KELLY DAY 

1.  Recovery began at mission altitude with a command that could be initiated internally or via remote control.  If the vehicle was configured for test range flight, range timer logic would command recovery to prevent annoying the FAA or citizens in case remote control was lost for a pre-set time.  In operational configuration recovery could only be commanded remotely.

2.  The recovery sequence began with deployment of the drag chute and shutoff of the engine.  The drag chute, in the cap at the very end of the chute can, is an 8 foot ribbon-type parachute.  The cap is held on by two screws; internal initiators fire to shear the screws and aerodynamic forces pull the cap free and extract the drag chute.  The drag chute is initially reefed by a line that passes around the base, and a pyro-activated cutter cuts the reefing line after the initial shock of opening.  The engine is shut down by closing the main fuel solenoid and starving the engine.  When recovery was commanded, unneeded systems were removed from the DC bus to avoid an excessive drain on the recovery battery.

3.  As the drone fell from altitude in drag, it would rapidly pitch over, as the flight controls were disabled.

4.  As the vehicle passed through 15K feet, barometric switches passed power to the main chute can.  The can is held in place by three disks, attached to plungers internal to the can.  When recover power is applied, initiators fire to retract the plungers and rivets holding the outer disk are sheared, releasing the can.  Since the drag chute is attached directly to the aft end of the can, the main chute can is positively pulled from the aft bulkhead.  The parachute line passes along the upper right side of the drone to two attach points, both fore and aft of the center of gravity.  As the can is pulled free, tension on the line pulls the main chute and then the engagement chute out of the can.  The can and drag chute then fall free and play no further role.  The main and engagement chute begin to inflate, but both are reefed to prevent excessive opening shock.  Once fully inflated, the main chute is a 100 foot cargo chute and the engagement chute is a 28 foot special purpose chute.  The engagement chute has a bridle affair sewn into the canopy, and this bridle is part of a 10,000 pound load line that is loosely attached to the main chute directly opposite the aiming gore on the main chute; the load line then passes outside the main chute risers to a handclasp affair that is also the attach point for the main chute risers.  At the same time the chutes are deployed, the dump valve opens under the main fuel tank, ensuring that any excess weight is removed.

5.  Normal recovery sequence involves the helicopter flying over the engagement chute at about thirty knots, with the same rate of descent (1000 fpm) as the drone package.  The CH-3 (or -53) has two poles extended below the aft cargo deck, with a treble hook suspended between them.  Any of the three hooks will tear through the fabric of the engagement chute canopy, and catch the engagement bridle.  At this time the engagement hooks pull free of the poles.  As the chopper continues its forward motion, it pulls the load line free of the main chute, and takes more and more of the drone’s weight (between 1700 and 2700 pounds, depending on the drone type).  The lines on the chopper terminate at a steel cable that runs underneath and into a well cut in the floor to a floor-mounted winch directly under the main transmission and rotor blades.  As the weight increases, the winch initially allows rapid unwinding of the winch reel to avoid shock loads.  As the rpm of the reel increases, a hydraulic brake begins to attempt to slow and then stop the winch.  Load sensors in the winch mechanism will normally stop the descent of the drone after about 200 feet.  At the same time the weight is being transferred to the load line, the load line is also transferring weight to the side of the handclasp away from the part that is suspended by the main chute.  When most of the weight has transferred to the load line, a rivet fails in the handclasp, releasing the main chute line.  The main chute then falls free and of course behind the drone/helicopter formation.  In SEA the main chute then became a prize for anyone who found it.  In some cases, the chute fell to the ocean and was lost.  When the handclasp operates, a micro-switch is closed in the handclasp, and a 5 foot parachute attached to the aft bulkhead is release by a reefing cutter, stabilizing any drone oscillations.  As soon as the drone is stable, the winch reels in all but about thirty feet of the load line.  The airspeed of the helicopter is restricted until the drone reaches this stowed condition.  When the drone is brought back to the operating base, the winch then lowers the drone onto a fuel bladder that is filled with water.  The load line is then cut and the drone belongs to maintenance.

6.  A water recovery sequence begins in the same manner, up to the point of engagement.  Occasionally, the hooks will tear the engagement chute without catching a bridle point.  This is known as a ‘tear through’ and usually results in enough damage to the engagement chute that it no longer flies above the main chute.  When this happens, the chopper crew is helpless and must wait for ground/water impact to make the recovery.  If the drone lands in water, exposed contacts on a salt-water switch close a circuit that fires an initiator below the handclasp, separating the parachute system from the drone.  The salt water switches also cause the dump valve to close, preventing water from filling the main tank.  The drone has a spring on the forward bridle attach point that lifts the riser about two feet.  The chopper crew has a hooked pole that allows them to manually attach the engagement hook to the bridle and they can then lift the drone from the water or ground.

To see pictures of an actual MARS recover click on the "MARS Recovery link at top of page

"FREEDOM ISN'T FREE"

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"HELICOPTERS" - THE ONLY WAY TO FLY

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