Wednesday, August 5, 2009
Chapter 15: Flying Heinemann's Hot Rod
The A-4 Skyhawk was operated by the Marines in the Forward Air Control role in Vietnam. The author flew a Skyhawk FAC mission out of MCAS El Toro in Southern California
With a small delta wing featuring leading edge slats, long-stroke landing gear and an arrester hook, the Skyhawk was equally at home on a forward airfield or an aircraft carrier.
Skyhawk! An evocative name indeed. The A-4 Skyhawk had been mainstay of Navy, marine and foreign air force light attack squadrons for more than thirty years. During this time the diminutive attack bomber had been known as "Scooter", "Tinker Toy", Bantam Bomber" and "Heinemann's Hot Rod", the latter name in honor of its designer, Douglas Chief Engineer Ed Heinemann.
The Skyhawk history was a classic. In January 1952 Ed Heinemann stated that he could build a lightweight interceptor with a weight of 12,000 lb. The same principles could be applied to a light attack bomber. The Navy challenged him on this. At that time the US Navy attack bomber specification called for a speed of 500 knots, a combat radius of 300 nautical miles and a maximum allowable weight of 30,000 lb. The challenge that Heinemann faced was to produce a lightweight, high performance attack aircraft. The El Segundo team was convinced that they could exceed the specification by ninety knots with an aircraft of half that weight. Others were skeptical. Even as piston-engined AD Skyraiders continued to roll off the line at Douglas's El Segundo plant adjoining Los Angeles International Airport, Heinemann's team worked on the design of this revolutionary attack aircraft.
Exceptionally rigorous efforts to reduce weight led to a number of innovations, such as integration of much of the avionics, and design of a special 40lb ejection seat. A takeoff weight of 14,600lb was achieved, thus vindicating the team. In June the Navy issued a contract for two prototype aircraft. The price was to be less than $1 million for each aircraft.
The design of the Skyhawk stressed the use of simple standard sheet, strip and extrusions. Forgings were almost eliminated. The wing was a one-piece structure, small enough that it could fit on standard carrier elevators without requiring the complexity of a wing-fold. The 260 square foot delta wing formed an integral fuel tank, with top and bottom skins machined from single sheets. Spars and stringers were made continuous from tip to tip. To further simplify the structure, the front spar was machined in a single piece, then bent in a heated die. The gear retracted forward, with the main wheels turning through ninety degrees to lie flat in the forward part of the wing. Following the trend set in the design of the F-4D Skyray, the stick could be extended to increase mechanical advantage to retain manual control in the event of hydraulic system failure. The rear fuselage and tail unit could be removed completely to change the engine.
Douglas test pilot Bob Rahn first flew the XA4D-1 on 22 June 1954. Buffeting of the rear fuselage led to the adoption of a “sugar scoop” fairing at the base of the fin to smooth the airflow over the rear fuselage. A simple flight test expedient, this was to be retained on all production Skyhawks.
During the Vietnam conflict Skyhawks flew from south-east Asian airfields and carriers to hit targets in North and South Vietnam. The agile Skyhawk proved well suited to the close air support missions. A 300 US gallon buddy refueling store was developed by the El Segundo team to permit the A4D to double as a tanker. A fixed flight refueling probe was fitted on the starboard side of the nose of later production Skyhawks. Over Vietnam this flight refueling capability of the A-4 proved itself many times in keeping Skyhawks airborne when the carrier’s flight deck was temporarily fouled. On occasion “wet-winging” was practiced, when Skyhawks with battle damage and losing fuel were simply plugged into the tanker and continued refueling all the way back to the carrier.
This Marine A-4 is carrying three external fuel tanks, and is hooking up to a Marine KC-130 tanker in preparation for the long over-water deployment from California to Hawaii.
Ordnance carriage was originally limited to 3,000lb on the centerline and 1,000lb under the wings. In addition to bombs, the Skyhawks could also carry HVAR rockets, tactical nuclear weapons, Zuni or Mighty Mouse rockets, or Bullpup air-to-surface weapons. A pair of 20mm cannons with drum feed was mounted in the wing roots.
For many years the Blue Angels Demonstration team used the A4F version of the Skyhawk. It had exceptional control harmonization, good thrust/weight and engine acceleration. The Blue Angels flew very close formation, stacking their dark blue Skyhawks only a couple of feet apart. They were very skilful pilots.
A two-seat version, the TA-4F was produced, with the fuselage extended twenty-eight inches and the fuselage fuel reduced. The Marines used this in Vietnam as a FASTFAC Forward Air Control aircraft. The orange and white TA-4J was in use as the advanced trainer for the USN.
In service the Skyhawk airframe proved very tough and previous versions were consequently in demand for retrofit. In fact the A-4B was turned into the A-4P and -4Q for the Argentine Air Force. These were used extensively in the Falklands conflict of 1982. Sixteen different models were built and a total of 2960 had been built by the time the last Skyhawk came off the line in February 1979.
By the mid-eighties, the US Marine Corps at El Toro in Southern California had one of three squadrons still operating the OA-4M version in the Forward Air Control (FAC) mode. The OA-4M was painted in low-visibility gray, carried an improved avionics fit in the humped fairing on the top of the fuselage and was liberally sprinkled with antennae.
I was invited by the USMC to fly a practice FAC mission in a Marine Skyhawk with Lt.Col Ed Schriber, Commanding Officer of H&MS-13. The task of the OA-4M Skyhawk being Forward Air Control in VFR conditions, it was primarily used as a high-speed platform for spotting and marking targets. We briefed for a mission in which Col Schriber was to demonstrate various Forward Air Control tasks, include simulated attacks, and to give me a chance to sample the handling qualities of the Skyhawk. On FAC missions the Skyhawks normally flew with two fuel tanks on the inboard pylons and two smoke marker rockets on the outboard stations. For our mission we carried a single centerline tank. This would give us a total of 6,400lbs of fuel for a takeoff weight of 19,500lb. Our mission duration of ninety minutes would get us back in the pattern at El Toro for some practice GCAs with 2,000lb of fuel.
After I was fitted out with my flight equipment, we walked out to the Skyhawk, one of the A-4s parked amongst the F/A-18 Hornets, RF-4C Phantoms and KC-130 tankers resident at El Toro. I climbed a ladder to the lofty cockpit of the Skyhawk, while Col.Schriber pre-flighted the Skyhawk. Once strapped into the Douglas Escepac ejector seat in the rear cockpit, and Col Schriber was aboard, I had a chance to view the equipment. Flight instruments and radio control panels were directly in front of me. The FAC aircraft were outfitted with UHF and FM radios to enable them to communicate with the FAC on the ground, the direct air support center or the airborne strike force simultaneously. By modern standards the Skyhawk had a simple avionics fit. Navigation was by fifties-vintage TACAN. Fuel and instruments occupied the right side of the panel. With full dual controls in my rear cockpit, there was not a lot of excess space compared with more modern fighters.
An air cart wound up our J-52-P-408 jet engine. Once the engine was running and the ground crew had checked the control surface movements were OK, we armed our seats by pushing up on the “headknocker” lever in the headrest. Aptly named, this gained your attention by giving you a smart rap on the head if you forgot to stow it.
With callsign OUTLAW 01 we taxied down to the end of runway 07, canopy still raised to let in some breeze against the oppressive heat of the 80F day. As we turned onto the active runway, the canopy was lowered and locked. Ed Schriber brought the J-52 up to full power and released the brakes. With 11,200lb of thrust thundering behind me, acceleration was rapid and we hit our target speed of 105 knots as the yellow 6000 ft marker flashed past. At 147 knots a firm rearward stick movement raised the nose. I felt the long-stroke gear extend as we rotated. Then we were airborne.
As the gear retracted we started turning left, heading south-west and out over the coast, over the Pacific towards San Clemente Island where we could practice our FAC work. For our airwork, our Navy controller, callsign BEAVER, allocated us airspace on the 185 TACAN radial of the San Clemente beacon. Once we were en route and level at 12,000 feet, Col. Schriber demonstrated the classical handling of the Skyhawk, starting with a clean stall. As our airspeed dropped through 150 knots, medium buffet started shaking the airframe. I twisted round in my seat and watched the aerodynamically-operated slats of the tiny delta wing creep out. Slats on the Skyhawk improved low-speed handling for carrier work, but during Air combat maneuvering (ACM) or formation flight they had been known to deploy asymmetrically, with dire results. Schriber drily informed me that when the Blue Angles flew their A-4Fs, they wired their slats permanently closed to prevent any unintentional deployment.
Another day at the office. This aviation writer trades his pen for the rear cockpit of the Marine A-4 Skyhawk, setting off for a Forward Air Control Mission
We continued to slow down and in heavy buffet eventually the nose dropped straight ahead in a classic stall. The addition of power and forward stick got us back into level flight. It felt just like a much smaller aircraft. As we accelerated, I looked back over my shoulder at the wing to see the slats inching back in.
When the TACAN showed that we had reached our assigned airspace, I tried a few aileron rolls. Roll rate in the Skyhawk was impressive, well in excess of 200 degrees/sec, even though I was not using full lateral stick deflection. Roll reversals were spectacularly fast. Rolling to ninety degrees of bank when entering a turn from level flight was abrupt and almost instantaneous, although I found that I could easily overpull into buffet. After a few minutes of maneuvering I started to appreciate how the agility and small size of the Skyhawk made it particularly suitable for FAC work, especially when combined with the low IR signature of the non-afterburning J-52.
I extended my repertoire to include wingovers, effortlessly soaring to 21,000 feet and ninety degrees of bank at the apex of the wingover while turning through 180 degrees of heading. Control harmonization was just right and the Skyhawk was a delight to fly. As we headed back towards San Clemente Island along our TACAN radial, we were flying above scattered alto-cumulus with the Pacific far below. I picked a cloud as an aiming point and found that barrel rolls to left and right were exhilarating and I found the Skyhawk a viceless aircraft.
We descended towards the island for our first simulated FAC attack, skirting the cloud and leveling at five hundred feet, turning tightly to the right with my g-suit squeezing my lower body as the g-force increased. We paralleled the mountainous spine of San Clemente Island which rose to 2,000 feet off our port wing with the peaks vanishing into cloud.
At the pre-flight brief, we had briefed for a FAC attack with our Initial Point(IP) at China Point. From the complexity of the briefing it was obvious required a lot of practice and co-ordination, with the front–seater flying and firing the smoke markers while the back-seater was responsible for mission planning, communications and cueing the pilot to landmarks while traveling at high speed. Extensive pre-flight planning was the key to success, said Ed Schriber, just as it was in Vietnam. Navigation was by 1:50,000 scale maps in the target area. The FAC Skyhawk was the pivotal point of the attack mission, and timing was critical to co-ordinate with the other strike forces.
I remembered Schriber’s words as China Point slid past the port wing. We accelerated to 350 knots under the stratus overcast. The clock was running down towards zero. There was not much room in the cramped cockpit to keep track of our progress along the line drawn on my folded map and as the coastline streamed past, one indentation of the coastline looked very much like another.
Our target was the distinctive shape of Pyramid Rock on the southern tip of the island. My radar altimeter sprang to life as we angled in over the coastline, the needle jiggling down from five hundred feet. Peacetime regulations kept us purposely high, and the speed was similarly kept down for my benefit. Wartime would see the Skyhawk streaking for the target at a mere fifty feet, with speed up to 500 knots for missile avoidance.
Even so, it all happened very fast. The target appeared momentarily over Ed Schriber’s helmet before he snapped us into a 4g climb, rolled inverted and pulled the nose down to the target. Pyramid Rock reappeared inverted in the windscreen, expanding visibly towards us. We rolled out smoothly , momentarily wings-level, as the clock hit zero. In wartime, the smoke rockets would now be on their way.
Jinking violently to the right to confuse any ground gunners, we reversed to the left so violently that my helmet bounced off the side of the canopy. A second later we were out low over the beach with the water streaming past below as we made our escape. During our flight back to El Toro I took the opportunity to regain my breath.
Back in contact with the Controller at El Toro, Ed Schriber completed the first GCA without fuss. I carried out the second GCA, with a less polished performance. It had been some years since I had flown a radar approach. Following the instructions in my earphones I was talked down and this time overshot from overhead the runway approach lights. A further GCA by Schriber culminated in a touch-and-go with a firm carrier-type landing, then as the power was brought up the Skyhawk leaped into the air again. We followed this with a couple of tight visual circuits. During each downwind leg, with the humid atmosphere at low level, my air conditioning vents spewed out jets of mist which added a sense of theatre to the cockpit. Our final landing, on cue, was ninety minutes after takeoff, with the anticipated 2,000lbs of fuel still on board.
Precision was the essence of FAC work. This mission had been a graphic demonstration of how the FAC Squadrons fitted into the overall scheme of things in supporting Marine Air Power.
at 8:57 PM