Mar 29 2013

Helicopter In-Flight Refueling Posted 11 years 38 days ago ago by Admin

By Brad McNally, Contributing Editor

In December of 1994, a nor’easter sank the 450 foot motor vessel Salvador Allende in the North Atlantic.  Onboard the Ukrainian registered freighter were 31 crew members who were left stranded, battling for survival against 30 foot seas and 60 mile per hour winds.  The crew members were hundreds of miles away from land and the magnitude of the storm that sank the Salvador Allende prevented other ships from reaching the scene.  Although Canadian and American search and rescue planes had been able to locate survivors in the water and drop life rafts, a rescue would only have been possible by helicopter.  Due to the distance from land, this mission was outside the boundaries of conventional search and rescue and would require a special type of helicopter, one that was capable of aerial refueling. 

The typical search and rescue helicopter would not have the range to make it to the survivors and back, so the mission ended up with the men and women of the New York Air National Guard’s 106th Rescue Wing based out of Francis S. Gabreskie Airport on Long Island.  The 106th Rescue Wing flew the Air Force’s MH-60 Pavehawk helicopter and the HC-130P Combat King.  Together these aircraft were capable of conducting in-flight refueling, effectively giving the MH-60 a range based not on fuel capacity but rather on mechanical and physiological limitations.  The day after the sinking of the Salvador Allende, two MH-60s, Jolly 14 and Jolly 08, were launched from Gabreskie under the command of the senior pilot Lieutenant Colonel (LtCol) Ed Fleming.  Fleming was a veteran of the Vietnam and Persian Gulf Wars, who had spent 24 years in the Air Force and Air National Guard flying helicopter rescue missions.  However, even he had never attempted a mission like the one he was about to set out on that morning in December.  The two MH-60s would be accompanied by three refueling tankers belonging to the Air Force, Air National Guard and Marine Corps Reserves.  These C-130s would take turns not only watching over the helicopters, but more importantly supplying the fuel that would make this long distance rescue mission possible.  After flying 500 miles to Halifax, Nova Scotia, the crews stopped to prepare for the remainder of the mission.  The original plan was to fly for five hours to the location of the estimated 17 survivors.

The survivors and their locations were being monitored by Canadian and American fixed-wing aircraft.  Once on scene the helicopters would retrieve the survivors and return to Halifax.  If all went according to plan, the total trip would take around ten hours which was the maximum amount of time that the MH-60s were capable of flying before needing maintenance checks.  Once the Pavehawks got on scene, the aircraft monitoring overhead reported that the position and number of survivors were unknown.  Upon hearing this, LtCol Fleming and the Pavehawk crews could have turned back but elected to commence a search of the Salvador Allende’s debris field.  Eight hours into the flight one of the crew members in Jolly 14, Tech Sergeant Rich Davin, spotted a survivor.  Davin directed LtCol Fleming into place and then pararescue jumper Jim Dougherty jumped out of the helicopter to rescue the survivor, a man named Alexander Taranov.  After retrieving Dougherty and Taranov, both helicopters continued to search for survivors.  At one point they found a life raft from the Salvador Allende but none of the other crewmembers were located alive.  Having flown for over 10 hours and still needing to get their survivor medical attention, Jolly 14 and Jolly 08 along with their C-130 escort departed the debris field for Halifax.  In all, the two helicopters flew for 15 hours to rescue Alexander Taranov.  With the help of the three C-130s the helicopters aerial refueled 8 times over the course of the mission.  The mission set a new endurance record for a helicopter rescue. Only one other survivor from the Salvador Allende was ever found.  He was later located and recovered by a merchant vessel that participated in the search. 

In his book “Heart of the Storm”, Ed Fleming described how the coordination between the helicopters and C-130s made the refueling evolutions possible and how challenging the rescue mission was.  Fleming also mentioned that the rescue of Alexander Taranov occurred just before Christmas in 1994, and how the crews involved were grateful to have returned Taranov home to be with his family for the holidays.  Fleming remarked in his book how he still receives a Christmas card each year from Taranov, as a thank you and a reminder that he has had another year with his family in no small part because of the heroic actions of the rescuers.  For their extraordinary efforts the crews of Jolly 14 and Jolly 08 received the American Helicopter Society’s 1995 Captain William J. Kossler Award for “the year’s greatest achievement in practical application or operation of rotary wing-aircraft.”  However, the story behind the rescue of Alexander Taranov actually starts years before December of 1994 at Wright Patterson Air Force Base where a group of Air Force test pilots and engineers would lay the ground work that would make this rescue possible. 

In 1965, the United States was heavily involved in the war in Southeast Asia.  By this time helicopters had become a mainstay for military operations, especially for rescuing downed aviators.  The United States Air Force Air Rescue and Recovery Service (ARSS) specialized in this task.  One major problem for the ARSS pilots and crews was limited range and on scene time dictated by the finite amount of fuel that could be carried onboard helicopters in the 1960s.  The Air Force, specifically the Helicopter Systems Procurement Office at Wright Patterson Air Force base in Ohio, initially tried to fix this problem by making the fuel tanks larger.  However, they quickly realized that enlarging the fuel tanks would not solve the problem.  Major Harry Dunn was working in the H-3 Systems Program Office at the time and had recently been involved with a program evaluating icing on the H-3.  The test involved flying an Air Force H-3 behind a C-130 while spraying water off of the C-130s cargo ramp onto the H-3.  Based on this testing, Dunn believed that it might be possible to fly a helicopter behind a C-130 and conduct air to air refueling.

This technique was routinely used on fix-wing platforms but had never been used successfully with helicopters.  Major Dunn consulted some of his colleagues about whether or not this procedure would work.  Many of them thought that it would be nearly impossible for a helicopter at high gross weight to keep up with a C-130 even if the C-130 was flying at its slowest speed.  However, Dunn was undeterred and convinced Captain Don Eastman, an Air Force H-3 test pilot and Major Bob Nabors, an Air Force C-130 test pilot, to do some formation flying with the H-3 in a trailing position to evaluate the feasibility of helicopter aerial refueling.  Eastman began by flying the H-3 behind the C-130 cargo ramp but quickly found out that because of the airplane’s tip vortices, the areas just aft of the vertical stabilizer and cargo ramp had a very strong downwash.  Once in position in these areas, Eastman had a hard time controlling the H-3 and would enter a very quick descent.  Sometimes the descent would reach 2000 feet per minute with very little control authority.  After attempting this several times with the same results, Eastman decided to take a break.  In order to collect his thoughts he moved the H-3 from directly aft of the C-130 to flying formation off of the left wing tip.  Once in position on the wing tip, Eastman noticed that there was a significant power reduction for the H-3.   For some reason it took roughly forty to fifty percent less power to maintain position when flying off of the wing than it did when flying directly behind the C-130.

It was this discovery that made helicopter aerial refueling possible.  Originally it was thought that the power reduction was a result of a decrease in dynamic pressure, much like race cars use when drafting off of each other.  However, Eastman later proved in a graduate school thesis that this power reduction was a result of the vortex effect from the C-130’s flaps reducing the helicopter’s induced power requirement.  The upwash from the flaps increased the helicopter’s effective angle of attack, reducing the induced drag and requiring less power to maintain the speed needed to keep up with the C-130.  Armed with these new findings, Dunn went to the Pentagon and received money to modify a helicopter for a full scale aerial refueling test and the assistance of the Marine Corps refueling C-130s at MCAS Cherry Point.  In order to accomplish this testing, Sikorsky Aircraft mounted a dummy refueling probe to a CH-3C.  At the direction of the Wright Patterson commander of flight testing and in preparation for further helicopter aerial refueling testing, Don Eastman began fixed-wing aerial
refueling training in the F-100 and B-47. 

On the morning of 15 December 1965, Captain Don Eastman and Sikorsky Aircraft test pilots Dick Wright and Thomas Glynn took off from Marine Corps Air Station Cherry Point, NC to demonstrate the first in flight hook-up of a helicopter and fixed-wing aircraft.  Although the testing was being conducted by the Air Force, the helicopter was a Sikorsky Aircraft owned CH-3C.  Therefore, the Sikorsky pilots were onboard.  The probe attached to the H-3 was a dummy probe and the lines on the C-130 tanker were dummy lines with a real nozzle.  This was done intentionally so that a hookup could be made but no fuel would be transferred.  The crew flew a morning flight and attempted several hook-ups without success.  Finally that afternoon, with Captain Eastman at the controls of the CH-3C and Marine Corps Captains W.J. Smith and R.R. Mullins at the controls of the KC-130F, Eastman successfully connected to the C-130 and remained connected for over five minutes.  Although no fuel was transferred, this was more than enough time than would have been needed to complete an actual fuel transfer.  The first successful connection was now accomplished and the stage was set for actual fuel transfer.  Actual transfer would occur later during the three phased helicopter aerial refueling test program conducted by Wright Patterson Air Force Base between August of 1966 and January of 1967.  Now Major Don Eastman was made the test director and flew every test flight in the helicopter.   He was once again accompanied by Major Bob Nabors, who flew every flight in the C-130.  Phase one used the CH-3C to define the operational flight envelope for helicopter aerial refueling.  Phase two tested the suitability for transferring fuel on the ground and in the air.  Phase three evaluated operational procedures and qualified ARSS flight crews for operational missions.  During the three phases, a total of 600 aerial refueling connections were made, including 90 at night.  The test program resulted in several changes which included a longer refueling hose and a larger drogue.  The larger drogue helped keep the nozzle higher and allow the helicopter to get in a position which maximized the upwash from the C-130 flaps and therefore required the least power.

The ARSS quickly adopted helicopter in flight refueling and before the war in Vietnam ended ARSS pilots were routinely using it to rescue downed aviators deep behind enemy lines.  Don Eastman would later test the aerial refueling capabilities of the HH-53B before heading to Southeast Asia as an ARSS Jolly Green rescue pilot himself.  Eastman flew the H-53 in combat and rescued downed aviators using the aerial refueling techniques he helped develop.  Although Harry Dunn, Don Eastman and the rest of the Air Force test group didn’t know it at the time, aerial refueling would forever change the face of helicopter operations and enable special operations and search and rescue missions that at one time would have never been possible.  They also played a hand in giving Alexander Taranov another Christmas with his family.