Tactical Helicopter – Chinook

The Chinook’s RAF role is explained by Ken Delve.

The role

OF ALL THE ROLES examined in this series, that of the tactical helicopter has the most recent operational introduction, having a history of less than 40 years. Like a number of the other roles, this arose as a secondary consideration to the original concept for the operational employment of the helicopter. Helicopter development was slow and uncertain in the mid 1940s but by the late 1940s the Americans had taken the lead in this sphere.

Despite these early trials, there was a distinct lack of enthusiasm for the potential of the new aircraft type. Nevertheless, in the 1950s the RAF identified a ‘requirement’ for helicopters to cover a number of roles. In practice the RAF received one type — the Westland Dragonfly, a licence-built version of the Sikorsky S-51. The use of helicopters in the Malayan Emergency encouraged wider development of such aircraft.

The potential of the helicopter in the tactical roles of troop and supply movement had been clearly demonstrated by the Dragonfly and Sycamore operations, what was needed was a helicopter capable of lifting more and going further. Development work on an aircraft to meet this early 1950s requirement led to the Bristol Belvedere, a twin-rotor, twin-engine design capable of lifting 25 troops (short range) or a 6,000lb (2,722kg) load. The first squadron, 66 Squadron, did not form until September 1961; the aircraft had had a troubled development period and came close to cancellation a number of times. It likewise had a troubled service life. Three squadrons operated the Belvedere — in the Far East it did a superb job, (despite numerous problems) between 1961 and 1969 and proved invaluable during the troubles in Brunei in the mid 1960s. In the Middle East, with ops in Aden, it struggled against even greater odds and despite once more proving invaluable for rapid deployment of troops, never truly established itself.

The Belvedere had certainly proved that an aircraft of its type was vital in the tactical support role and as the problems mounted and it neared the end of its useful life a requirement was written for a replacement. Among the contenders was the Boeing Vertol CH-47 Chinook and the intention was for the new type to enter service in 1970. However, for a variety of reasons nothing came of this and the project, and the Chinook, were abandoned in favour of smaller tactical helicopters (a change of emphasis which led to the development and entry into service of the Pumo).

As related above, the Chinook was looked at for possible RAF use in the late 1960s but rejected in favour of smaller types. However, ten years later the requirement for a heavier-lift helicopter emerged once more; this time there were no British-built contenders and the most obvious choice was the latest version of the previously-rejected Chinook! The prototype YCH-47A had first flown in September 1961 and the type entered service shortly afterwards, seeing extensive service over the next ten years in Vietnam where it revealed its flexibility and potential. Development of the type continued with new variants appearing and an ever-growing list of customers. The resurgence of interest in the late 1970s included the RAF and the first Chinooks (roughly equivalent to the CH-47C variant) went to 240 OCU at Odiham in 1980 and to the first squadron the following year.

With its two 3,750shp Lycoming T-55-L-11 turboshafts, the Chinook has a max speed of 180mph (290km/h), but a more normal cruising speed is 140mph (225km/h). The aircraft is capable of taking an incredible 22,000lb (9,979kg) load and thus making a significant contribution to battlefield support in a variety of forms. During the Falklands Conflict the single operational Chinook of 7 Sqn performed outstandingly, including on one occasion lifting 80 combat troops. Since then the Chinook has continued to be an essential element within the RAF SH (Support Helicopter) force.

The Mission

The eight-figure grid reference plots out to be a reasonably sized clearing in an area of woodland, a fairly typical Landing Zone (LZ) for a battlefield support mission. Details of the loads to be moved and the location of the Forward Edge of the Battle Area (FEBA) should be received shortly but in the meantime the task leader has to parcel out tasks to the remainder of the crews in the formation. At first sight it looks as if three or four Chinooks will be needed for the task.

The detachment has been operating from its field site alongside the army unit for five days and co-ordination between the two is well established. With the majority of the equipment camouflaged on the edge of the operating site it is only the helicopters themselves which give away the location — one of the problems of the Chinook is that it is too large to push away under the trees and cover with netting. However, the flying rate is high and the aircraft are rarely on the ground; both day and night missions are flown, the latter using night vision goggles (NVGs). Support elements are present with the Tactical Support Wng (TSW) providing the refuelling facilities with bowsers and pillow tanks and squadron groundcrew to service the aircraft whilst at the main base — at outlying stations the crew themselves carry out the aircraft servicing.

With the LZ plotted the other questions now have to be answered. What troops and equipment have to be moved? Is it better to shuttle the troops or re-rig the aircraft for maximum capacity? What other loads are involved — can mixed loads be used? Will the aircraft need to refuel? And, vitally important, what is the battlefield situation and therefore what tactics will have to be employed? A host of points to consider before the aircraft can carry out the task, so plenty for the crews to sort out. The army commander briefs the task leader on the requirements and general situation… a mixed force of troops and equipment, including heavy loads that will require underslung movement. The LZ is some 30 minutes’ flying time away and right on the edge of the battle area; the deployment is intended as a concealed build-up. However, the LZ has been secured by a ground party and a group from the Mobile Air Operations Team (MAOP) will have marked out the LZ and will act as aircraft co-ordinators. Despite the high air threat, including armed helicopters, in the task area no armed escort helicopters can be provided — the Chinooks will have to rely on their own door-mounted general purpose machine-guns to suppress any ground fire in the LZarea.

Details of the loads are examined and aircraft loading decided upon. Four aircraft should be enough for the first wave with a second similar wave following later. Two aircraft to take troops, one with vehicle and troops, and one with the underslung loads. The troop-carrying aircraft will go first in the formation as with less weight they will be faster and their ‘cargo’ will be useful in helping to secure the LZ should any problems arise. In view of the overall situation, the Chinooks will fly Nap of the Earth (NOE), hugging the contours and plan a Concealed Approach and Departure (CAD) run-in to the LZ itself. The idea is to get in and out without alerting the opposition and without giving away the exact location of the LZ itself.

The brief to the troops is short and sharp as they have all flown ‘Chinook Airways’ before and know the procedures and what to expect. The crewmen — two per aircraft — have prepared the cabins for their respective loads and as the time ticks away loading must be smooth and efficient. In two lines the 26 troops move into the body of the Chinook to take up the seats which run down both sides; the other aircraft has a greater complement of troops to ferry and so the floor seating is also brought into use. With their standard equipment, including rucksacks, the cabin appears full. Time is of the essence now…

«Fifteen troops to go, expect take-off in two minutes.»

The running commentary by the crewmen keep the front-end pilots informed of the progress of the loading. The engines are running and the Chinook is ready to go.

Troops on board. Ramp clear of ground.»

Two crewmen are watching front and back, they are the eyes of the pilots, who cannot see to the sides and rear of the aircraft. The Chinook lifts up and, as it clears all obstacles, transitions to forward flight. The second troop-carrying helicopter lifts at almost the same instant. Seconds later the third Chinook is airborne, the loading of the vehicle having gone smoothly since it was already prepared for flight and the driver had played the ‘quart into a pint pot’ driving game before. Meanwhile the aircraft with the underslung load is manoeuvring for the final pick-up. Again, the role of the crewman is essential; positioned just about over the load by one crewman, directions are then taken up by the other as he peers down through the floor hatch.

«Forward… Right… Steady… Forward… Five… Four… Three… Forward two… One… Steady… Steady…. Height good, position good.»

Stabilised over the load, the pilot looks for external references to maintain his position whilst the running commentary from the back continues…

«Load attached… Up gently… Taking the strain… Load clear of the ground… Good load.»

The Chinook has an incredible amount of power in its twin engines and even by doubling its overall weight, as it often does with such loads, it handles smoothly and accurately. Nevertheless, the effect of the great weight under the aircraft can be felt — especially during rums or if the load starts to oscillate. Slightly behind the other aircraft, the fourth departs the clearing and sets off towards the LZ.

A passing glance over the undulating and partly-wooded landscape would reveal nothing. The Chinooks seem to blend with the background at 120kts (222km/h) and less than 100ft (30m). Slow speed has two great advantages in that you can navigate by smaller features and search out every possible hiding place; and, the movement over the ground is slow enough not to register with the casual observer. The planned route on the map aims at avoiding all problem areas but the basic concept is to avoid being seen by anyone — if they don’t see you then they won’t fire at you! The handling pilot’s job is to keep the aircraft in the NOE environment — wriggle down a small valley, sneak around the edge of a ridge, even duck down behind a line of woods. Meanwhile, the other pilot or nav, concentrates on map reading, keeping to rough track and time to avoid known hazards and make the LZ as planned.

«See that wood on the ridge in the ten o’clock… put me down the left hand side.»

With the general direction fixed, the aircraft manoeuvres around to seek the best ground cover, even such gentle manoeuvres can be very uncomfortable for the troops down the back. Navigation cannot become the sole task of one or the pilots, there just is not time to spore and so a nav computer, the Tactical Air Navigation System (TANS) is employed to help reduce the nav workload. Programmed with a series of waypoints (turning points) the system provides steering information plus other nav data such as times and wind velocities. Cross referencing the system to the outside world makes life much simpler and the kit is updated at the turning points in order to keep it as accurate as possible. On time and looking for the next turning point, a windmill on the edge of a wooded ridge, TANS gives 4 miles (6km) to go and so it should show any time… wooded ridge in the two o’clock, follow it along to the left and… yes, a windmill — minus its sails. A 90° turn on to the next track so roll on the bank, keep the yaw pedals central, play the lever against the angle of bank and the Chinook flies around the corner just like a conventional aircraft — although in a much shorter distance. The reserve of power is excellent and the aircraft is responsive and agile, surprisingly so for its size and seemingly square non-aerodynamic shape. Even a 30kts (55km/h) wind causes little trouble although it is wise to anticipate sharp areas of wind turbulence caused by local wind effects on hills and valleys.

In between carrying out routine checks of aircraft systems and keeping an eye on troops or cargo, the crewmen act as the main element of lookout. Flying in NOE means that the handling pilot can spare no more than the odd glance above the horizon, the other front-ender shares time between navigating and lookout, but the latter is very restricted because of the aircraft’s general arrangement. Each of the rear crew has an area of responsibility to cover — the No. 2 from the front door scans from as far forward as he can see back to the six o’clock, the No. 1 crewman from that point to as far forward on the other side of the airframe as possible.

«Bogey, three o’clock, three miles. Left to right.»

Tally! Number two padlock.»

There is every chance that the aircraft has not seen the helicopter and so to react too early would be counter-productive, better to watch and wait… and try to find even more cover, A sharp manoeuvre would almost certainly give the aircraft’s position away by a glint of the rotor or a sudden perceived movement where a moment ago there was none. The commentary on where the aircraft is and what he is doing keeps the front-end informed as the ‘padlock’ is passed from one crewman to the other until the aircraft vanishes from sight. There will be others and the vigil cannot be relaxed for a moment.

Air threats are not the only ones to worry about; for the ultra low-flying helicopter one of the biggest threats comes from birds — birds and aircraft don’t mix and to hit a flock of even smallish birds can prove disastrous. A cry of «birds’ from the front-end gives the rear crew an instant to brace for the sudden violent manoeuvre followed by an equally violent reverse to get the aircraft back down out of sight. For the troops it is yet one more moment of discomfort as their stomachs leap one way and then the other.

Eight miles (13km) to the LZ and the Initial Point for the CAD should appear around the corner of the next ridge. From this point on, the aircraft sinks even lower, often down until it is almost touching the ground. As the height is reduced, so must the speed be decreased to allow for manoeuvre avoidance as the route down the 50:000 scale map is followed bit by bit. Down to 50ft (15m) and speed back to sneak along a line of trees and around an isolated farmhouse. Drop down into an almost imperceptible fold in the ground between two fields. Suddenly…

«Break left… SAM four o’clock coming towards… flare gone.»

The tell-tale smoke trail of a shoulder-launched infra-red homing missile picked up by the crewman and the pilot throws the aircraft into a violent manoeuvre whilst the crewman hits the dare button to fire off an infra-red decoy (IRD). The white hot flare provides a much better ‘target’ for the missile and the helicopter resumes its approach to the LZ. The CAD is even more important now as enemy troops are without doubt in the area! One route in and one route out… 4 miles (6.4km) to go, time to get the back-end ready for the LZ. Red light on and pre-landing checks complete. The plan is to carry out a run-on landing as the quickest way of getting into position. Two miles (3.2km) to go, pass down the left of a ruined church so the tracking looks good, over a small rise in the ground and the LZ should appear. Assess the final terrain, cover and wind, to decide on the approach to give the best chance of getting into position first time — and leaving room for the other Chinooks to get in with their loads.

Assessment of the landing area is made in seconds as the aircraft is positioned for its approach, the MAOP team presence means that no recce of the site is necessary; without this knowledge that the site has been surveyed as suitable, and dangerous areas highlighted, a quick visual recce of the LZ would have been needed — with the consequent delays in dropping off the troops and additional exposure to enemy attention. Speed reducing as the aircraft descends towards the chosen spot… assessment of the landing area itself, surface condition and type, slope and so on. Commentary from the rear…

«Tail clear. Clear forward and down. Clear below, slight tail wheel down slope.»

Speed continuing to trickle back as the ground approaches… 20kts (37km/h) as the rear wheels touch… the aircraft rolls forward with the nose 10° in the air. As the speed decays away to zero so the nose is lowered to the ground.

«LGS to ground. Clear ramp down.»

At the same instant the ramp control lever is operated at the back right hand side of the Chinook and the hydraulic ramp swiftly lowers… green light on… thumbs up from the crewman and the troops are on the way out of the aircraft.

«Ramp down. Troops out. Six to go… Last man out. Ramp coming up. Ramp clear of ground.»

A mere 20 seconds and the aircraft is rising from the grassy surface into the air, turning and moving away over the LZ towards the exit route of the CAD. One minute later and three of the four helicopters have delivered their loads and are already back down at below 50ft (15m) leaving the area to return for the next wave of troops. The aircraft with the underslung load arrives at the LZ and is marshalled to the drop points — no point just dumping it and then having to get someone to move it around by hand! Over the point under the direction of the crewmen with the traditional commentary calling the pilot to a steady hover before easing down to take the tension off the strop and have the bad disconnected.

Within minutes of the arrival of the first Chinook the LZ is deserted — there is no sign that anyone has been there; all troops and equipment are safely under cover.

Future developments

The requirement for tactical troop and equipment lift will, if anything, increase over the next few years as it not only increases a commanders flexibility but also acts as a force multiplier by allowing units to almost be in two places at once. Chinook is well established in the role and although the other TS helicopter, the Puma, has a vital part to play in the scenario it cannot perform the same Herculean feats as its larger colleague. There is, therefore, no reason why the Chinook should not continue to provide RAF heavy lift TS for many years to come. Its one weak area is that of self defence in an increasingly hostile ground and air environment with a proliferation of anti-helicopter weapons systems — themselves proof that the helicopter is seen as a potent battlefield system.

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