Super Puma Bids For RAAF Order

New variants of a particular type of aircraft used to come out under a succession of the ‘marque’ numbers but in recent years manufacturers have taken to adding such appellations as ‘Super’ or ‘new generation’.

This is rather unfair in that it tends to submerge those cases where there are genuine and fundamental changes that clearly differentiate a new aircraft from its predecessors.

But ‘super’ seems a fully justified appellation in the case of the Super Pumas now rolling off the production line at Marignane in the south of France in both civil and military versions.

The Super Puma represents a considerable advance on the original 1962 Puma design for a French army transport helicopter, despite an outwardly close resemblance.

During 1974, when early Pumas were completing five years of operational service, Aerospatiale began work on a major revision of the design to take advantage of technological advances and experience of users.

By incorporating some new materials but retaining most” of the conventional all-metal semi-monocoque fuselage construction, Aerospatiale was able to improve almost everything about the helicopter, to the extent that commonality between the original Puma and the new Super Puma is only about 15 per cent of components.

The Super Puma is fairly new into service, French certification for VFR and IFR operation in A and B categories being obtained in April 1981, with US and UK certification following soon after.

The basic Super Puma is now represented by the AS332B military model with accommodation for 20 troops and the AS332C civilian version carrying up to 17 passengers (these having the same cabin volume as the original AS330 Puma of 11. 4 m3).

In the civilian AS332L and military AS332M, the cabin is stretched by 76 cm to provide room for four more seats through an increase in volume to 13. 4 m3, with an additional window on each side of the cabin.

Aerospatiale’s philosophy was to provide two popular models – the short AS3328 for the military user requiring a gross weight about120-150 kg less than the UM, depending on equipment, for maximum performance in hot and high environments and the longer AS332L with extra underfloor fuel cells, for civilian offshore operators needing high passenger capacity and long range.

Short-fuselage aircraft carry between 17 and 20 civilian passengers, reducing tonight to 12 in the VIP versions with a toilet and galley, while the AS332B’s usual load of 20 troops falls to 16 when crash-survivable seats are fitted. The medivac load is six stretchers and a similar number of seated patients or nursing staff.

In its longer configuration (AS332L/M) the Super Puma will seat up to 24 civilians – or between nine and 15 VIPs – or 18 to 24 troops (according to seating type) and nine stretchers plus three sitting personnel in medical roles.

For lifting operations, a floor hatch beneath the main rotor is provided for attaching loads up to 4500 kg to an internal sling. When no hoisting capability is required, the cargo sling well can house. an extra, quickly removable fuel cell, increasing fuel capacity to 2590 litres in the AS332C and 3090 litres in the AS332L.

In a phased improvement over the next four years, the Super Puma will receive new engines, a new main rotor head and tail rotor and finally improved blades. The new Spheriflex rotor head, which improves performance and lowers vibration, will be completely interchangeable with the existing head for simple retrofitting.

Aerospatiale is also proposing modifications to the avionics, including an automated digital flight information system

The Super Puma is fully certified in France, the US and UK and is certified for operation in icing conditions by the US and France – the first helicopter to achieve this. Certified for operations in temperatures up to plus 50°C and – 40°C (soon to be extended to – 50°C), the Super Puma has established an unofficial altitude record of 30,000 feet (over 9000 metres).

The Super Puma keeps up maximum performance in hot and high conditions, with takeoff at 9 tonnes up to 40 degrees at sea level.

It has a comprehensive autopilot for Catll landings in visibility down to 100 feet vertically and 400 metres horizontally. At 8. 6 tonnes, the stretched version can carry 25 troops (this includes one in the jump seat just behind the pilots) at an economic cruise of 135 knots (VNE 156) arid a rate of climb at sea level of over 1500 fpm. Hover ceiling is OGE ISA, 5740 feet; ISA plus 20C, 2620 feet; ISA plus 35C, sea level.

Field maintenance is simple with engine cowlings opening to provide ‘walk-in’ access to engines which can be changed in the field with the use of a modest amount of equipment that can be carried on board. Engine changes with two men have been demonstrated in under 30 minutes and a main gearbox change has been accomplished in six hours by three men, including remove and replacement of rotor head and blades.

Since the Super Puma is designed for civil as well as military use, and there is no fundamental difference between the two variants, military fliers would be entitled to inquire about damage tolerance and crashworthiness in the Super Puma. Full-scale mock-up tests showed that in descent rates of up to 10. 5 m/sec (34. 5 ft per sec) the greater proportion of energy was absorbed by the bottom of the airframe, leaving the cockpit not substantially reduced.

In addition, there was no detachment of heavy components such as the engines, rotor or gearbox, under-floor fuel tanks remained intact and instrumented dummies did not show deceleration in excess of the limiting 20 G in 0. 1 sec.

Features contributing to this crashworthiness include reinforcement of the cabin and cockpit floors, main landing gear attachment frames, engine mountings and the general tail boom structure.

Reduction gear components are similarly protected from battle damage with high-tensile steel gears and bearings being designed to function for an hour after loss of lubricant. In one spectacular test, small-calibre rounds were fired into the main transmission case during operation, seizure began only after the tenth impact.

Self-sealing fuel tanks installed in the Super Puma are good for at least 40 minutes after penetration by 12. 7 mm fire and as an additional safety measure, anti-combustion foam is automatically injected into the tank if it is hit by incendiary rounds.

A rigid fire-retardant foam fills cavities between tanks and the helicopter’s structure.

Flight crew in the military variants are protected by composite light alloy/Kevlar armour, specially developed by Aerospatiale and capable of stopping a12. 7 mm penetrating projectile fired from 200 m at right angles to the surface. Other battle damage protection comes from the robustness of components or systems redundancy.

Following analysis of helicopter losses in combat, the Super Puma’s designers equipped it with dual hydraulic and electrical systems, the former drawing power from self-regulating pumps driven by the main gearbox.

Each hydraulic system supplies one set of servo unit chambers for flight control, the left-side also operating the autopilot, rotor brake, undercarriage and wheel brakes, while a gearbox freewheel maintains power even with both engines stopped.

Thus, the Super Puma can make a controlled landing with both engines out and one hydraulic line damaged- a hand pump lowering the undercarriage in the event of power loss to this function.

On the ground, the helicopter can run its port engine without turning the. rotors, allowing hydraulic systems to be operated. Dual electric circuits have an automatic switchover in case of damage to one.

For military operations; the fully-composite rotor blades are part of the Super Puma’s survivability package, being unaffected by the impact of small projectiles.

They have been successfully tested under maximum flight-load conditions for 40 hours after 12. 7 mm calibre impacts against skin and spar attachment areas.

In blade repairs, there are four levels of operations starting with line repairs, which are very simple, involving cold bonding, which most operators can do. The next level requires special facilities but still only cold bonding, while the third and more complex level requires heating and specially-trained staff. In the fourth stage, the blades are returned to the factory. Blade damage can be repaired at the factory and the limiting factor is usually economics rather than \ the technicalities. Blade tips mangled after collision with trees are a common problem and up to a metre of blade has been cut off and replaced.

Over 10 years, the Aerospatiale’s blade manufacturing and repair shop in Paris has seen blades that have been in use for over 20,000 hours going back to customers after servicing. Most repairs do not appear to affect fatigue life.

Visitors to the blade facility are often intrigued by the woodpecker-type noise which turns out to be a quality control measure as technicians tap blades with a coin to detect hollows or delaminations – rather in the manner of those men who hit train wheels with hammers.

Further checks are made with laser equipment calibrated to detect anomalies as small as 1. 5 angstroms but since the early 80s, this has never caused the rejection of a blade that had passed the tapping test. In fact the move to composites virtually meant a return to woodworking techniques which the industry thought it had left behind several decades ago.

The work is meticulous but simple in theory, and toolboxes resemble a home handyman’s kit, including mainly simple things like straight edges, scalpels and chisels.

In selecting a new engine for the Super Puma, Aerospatiale rejected an import such as the well-developed GE700, which powers the Blackhawk, and chose to develop a new power plant in conjunction with Turbomeca. Metal was cut for the first Makila engine in June 1975 and the initial test-run took place on the bench at Bordes in January 1977.

Although it failed to reach the most optimistic projections of a 30 per cent lower specific fuel consumption, it did achieve a very useful 18 per cent fall over the Puma’s Turmo, together with a substantial increase in power-to-weight ratio and diminished maintenance requirements, resulting from a smaller number of components. The Makila has 47 per cent fewer parts than the competing GE engine and the French claim they have never had an engine failure in flight.

Power reserves provided by the Makila allowed Aerospatiale to take the unusual step of launching simultaneously both a standard and stretched version of the same aircraft, each with military and civilian derivatives.

One spectacular achievement was the engine’s ability to transition from idle to full power very rapidly- a valuable safety feature. For pull up, full power is available in 0. 6 sec while at 2000 feet in 33°C, response time is four seconds, compared to seven for the GE. Aerospatiale are very proud of how they have achieved this through a direct link between the collective pitch control and governing system.

A wide range of avionics is available, including VHF, UHF, tactical HF and HF/SSB radio and intercom. Navaids can involve radio altimeter, radio compass, VLF Omega, VOR/ILS with glide path, Decca navigator/flight log and Doppler with an integral radar scanner position in the nose.

The SFIM 155 autopilot can be coupled with the navigation and microwave landing systems and the helicopter will automatically transition from one flight mode to another, including levelling off at 100 feet during a Cat II ILS approach.

With dual control in all versions, the Super Puma is flown by a single pilot in VFR conditions and two crew for IFR, a jump seat providing accommodation for a third crew member- or load-master/jumpmaster dispatcher in military models.

Aerospatiale Helicopters’ Design and Engineering Director, Mr R. Mouille, who is often described as the “father and mother’ of the French helicopter industry, believes that despite emerging new rotary wing concepts, there is a great deal of future left for ‘pure’ helicopters and Aerospatiale’s in particular.

Pure helicopters will always have limitations of stall from the retreating blade and mach numbers with the advancing blade but Aerospatiale is working on adapting blade profiles to improve lift efficiency and move away the stall with special definition tips.

“In five to 10 years it will be possible to commonly fly helicopters at 200 knots but it will be difficult to go further because the limitations are still there and we need new concepts like ABC or compound or tilt-rotor,” Mr Mouille said.

“The most promising for speed is the tilt rotor-In 10 years it could be flying at 300 knots but it has a higher empty weight and higher power stall-there will always be trade-offs.

“We have made a lot of comparisons and think that the Spheriflex rotorhead, on weight, vibration, drag and cost, is the best solution.

“In the Spheriflex, the hub is integral with the shaft and the blade yoke is close to the root.

“There are no other main parts-only accessories like thrust bearings.

“It could not be possible to make something more simple.

“It is the future.

The Spheriflex means a 65 kg weight saving and provides better handling and reduced vibration and maintenance. It will be in production in 1987 and will be retrofittable to all Super Pumas. Aerospatiale has tested the Squirrel’s Starflex rotor on the Super Puma and it worked well but hub drag was higher than a conventional hub and about 12 km/h speed was lost. Spheriflex has comparable flexible arms and blade attachments but the attachment points are closer to the centre to reduce drag.

Another feature for which Mr Mouille predicts a big future is the shrouded rear rotor, which already features on Aerospatiale’s Dauphin.

The shrouded rear rotor works only in hover-there is no power in the rear transmission most of the time and Dauphins have demonstrated that they can continue to fly with the rear rotor inactive, so long as they can make a run-on landing to avoid torque.

“I regret we did not have the shrouded rear rotor on the Squirrel but we had to keep it cheap-it used to cost three or four times as much but now costs are about the same so a Squirrel with a shrouded rear rotor may be available in 1988-89,” Mr Mouille said. Shrouded rear rotors could also be retrofitted to existing Squirrels to improve their performance. They have been tested on the Super Puma but increasing disc loading has shown there are limits to the concept and it is unlikely to be applied to helicopters heavier than five or six tonnes.

On industrial offsets should Australia buy the Super Puma. Mr Mouille points out that industrial cooperation means transfer of knowledge over 10 years instead of two. French helicopters have not enjoyed the best reputation for product support and maintainability in Australia due to their small numbers sold until recently. However, the ease with which the RAAF and RAN Squirrels have entered service has done much to suppress bad memories.

Current parts from Aerospatiale production lines have been offered as industrial offset for a Super Puma purchase but The naval version of Super Puma carries a hefty punch with its two pylon-mounted AM39 Exocet anti-ship missiles. Iraq has used this combination to good advantage against civilian shipping in the Persian Gulf in recent times. the French believe that cooperation should start in the design office, not on the factory floor-pointing out that there should be considerably more longer-term profit in participation in new anti-tank helicopters and the proposed Nato frigate helicopter.

Aerospatiale has proposed a number of casting and machining tasks on the Dauphin tail rotor gearbox including inputs, covers, main casings and accessory drive with a requirement of 50 sets per year.

They claimed that although this work is sourced 50-50 with their own plant at Marignane, there is a possibility for Australia to become sole source on some Super Puma components.

The French describe Australian prices as ‘acceptable’ but add that they are confident that the Australians will eventually become competitive. Aerospatiale has already signed a contract with Hawker de Havilland to make Dauphin cabin doors at its low-overhead Perth facility.

The French describe this as good work at competitive prices- after much negotiation. Meanwhile, GAF has a well-developed composite facility but has had difficulty in coming up with competitive prices – so far.

With sixty-two per cent of Aerospatiale turnover earned in export markets (the group employs 40,000 people in 18 plants and in 1983 had a 23,500 m franc turnover) the French are in nose-to-nose competition with the US-and they see the Asian region as most important for sales growth in the next 10 years. Aerospatiale angrily rejects US claims that they are subsidised by the French Government, although they admit they receive some loans which are repayable on export sales.

They retaliate by pointing out that they do not receive large development project orders such as enjoyed by us manufacturers.

Aerospatiale is in competition with five US manufacturers and although the dollar value of its sales and the combined total of the Americans, has remained roughly comparable over the years, the Americans total unit sales have been greater because of their concentration on smaller machines.

However in 1982, Aerospatiale introduced the Squirrel and the unit gap is now closing with Aerospatiale edging ahead in both units and value sold. It recently sold 90 Dauphins to the US Coast Guard and 1s now Co-operating with West Germany on a new antitank helicopter which will provide further strong competition.

Direct comparisons between two of flying machinery always dangerous but for what it is worth, here goes-

The Super Puma AS332B1 has a cabin floor area of 84 square feet (or 99 in the stretched version) compared to the Blackhawk’s 77.

It can carry up to 21 (25) troops, compared to the Blackhawk’s maximum of 19 and has an external load of 9920 pounds compared to the Blackhawk’s 8000 pounds.

Landing on slopes, it can handle 12 degrees longitudinally and eight degrees laterally while the Blackhawk can handle 15 degrees in any direction.

Its maximum useful payload is about 10,200 pounds, compared to a current 9520 pounds for the Blackhawk.

Maximum survivable crash descent rate is 10. 2 metres per second, compared to 12. 5 metres per second for the Blackhawk Although these figures may be argued in detail by the two manufacturers (both of whom keep changing theirs) what comes out clearly on any comparison is that the Super Puma has a substantially lower empty weight than the Blackhawk and a correspondingly high or useful load by a margin of at least 300 kg.

In summary, it is a bigger, more versatile helicopter, with more applications and capacity, at a lower price than its primary competitor – even if it does not fit the ‘requirement’ quite so closely.

NEXT ISSUE: The 146-page March edition of Australian Aviation will feature an in-depth analysis of the Sikorsky UH-60 Blackhawk as projected for RAAF service.