Water Car Engineer
ELITE MEMBER
- Joined
- Sep 25, 2010
- Messages
- 13,313
- Reaction score
- 8
- Country
- Location
It has taken some 25 years, but South Africa’s attack helicopter programme has finally delivered a fully operational aircraft to the South African Air Force (SAAF). On April 1, five upgraded Denel Rooivalk helicopters were formally handed over to the Chief of the SAAF, Lieutenant-General (Lt-Gen) Carlo Gagiano, at a ceremony at the Denel Aviation facility next to OR Tambo International Airport in Kempton Park, east of Johannesburg.
Six more will follow by the end of this year. All 11 of the upgraded Rooivalks – the aircraft is now formally designated as the Rooivalk Mk 1 and officially categorised as a combat support helicopter – will be operated by 16 Squadron based at Air Force Base (AFB) Bloemspruit, near Bloemfontein, in the Free State province.
The April 1 function also marked the official award of type certification to the Rooivalk (which translates into English as ‘kestrel’
. Type certification proves that the aircraft is airworthy, safe to operate and complies will all relevant regulations.
The double event was celebrated by the manufacturer, Denel Aviation. “I think it’s a major milestone,” says Denel Aviation CEO Mike Kgobe. “And we are very proud of it. The aircraft is qualified to international standards. It really is an achievement. I think it also is an indication of the capability of South Africa, because while Denel Aviation was the lead partner there were subsystem manufacturers behind Denel Aviation. So, it shows the capability of South Africa.”
Growing Pains
There can be no doubt that the image of the Rooivalk has suffered as a result of misleading and exaggerated official propaganda in the early years of the programme. The helicopter was conceived in 1985 and the first prototype made its maiden flight in February 1990. South Africans were told that it was a world beater, the best attack helicopter in the world, better than America’s Boeing AH-64 Apache. In reality, the Rooivalk was an experimental aircraft with enormous potential, but very far from being an operational attack helicopter.
The development of the Rooivalk proved to be technically very challenging, and budget cuts only compounded the problems. The original plan to build 36 production aircraft (plus the four prototypes) was abandoned and, in the end, only 12 were built, with the first of these production aircraft making its first public flight (not its maiden flight) in November 1998. Except that these were not really production aircraft at all – they were more like pre- production versions of an aircraft that was still under development.
Although deliveries began to 16 Squadron in January 1999, the Rooivalk was still far from operational. Basically, it had been issued to the squadron for test purposes. It could fly, and fly impressively (although there were, unbeknown to the public, some safety concerns), but it could not fight.
The huge gap between the original propaganda and the reality undoubtedly led to scepticism and cynicism regarding the Rooivalk programme among Parliamentarians, the press and the public. It also obscured what an impressive technical achievement the Rooivalk is.
While a quarter of a century is a long time, it is by no means unparalleled in the annals of the development of complex aircraft. Indeed, there is a pretty good parallel – the protracted development of the Eurocopter Tiger attack helicopter.
Originally conceived in 1984 as a Franco-German project, the Eurocopter Tiger programme has also been dogged by budget cuts and technical problems. The programme had to be relaunched in 1987, the first prototype flew in 1991 but the production contract was only signed in 1999.
While the simpler French combat support (escort/fire support) version entered service in 2005 and was first deployed on operations in Afghanistan in 2009, the more complex German (multirole/antitank) version suffered further delays and the German Army only began to receive operationally capable helicopters in late 2010, instead of the originally scheduled 1992. (The prototype of the multirole/antitank version for France and Spain, which differs from the German aircraft, first flew in 2007 and the first production examples are due for delivery early next year.)
New Bird under the Plumage
When originally assigned to 16 Squadron for testing, the Rooivalks were categorised as being Block 1A aircraft. They were subsequently modified to Block 1B status, and later still to Block 1E.
“We’ve made 130 modifications to the aircraft to take it from Block 1E to Mark 1, plus nine modifications to the ground support equipment,” reveals Denel Aviation Rooivalk Chief Design Engineer Dr Renier van Rooyen, who has been working on the Rooivalk programme since the middle of 1984 and has held his current post since 2003. “For example, the software in the mission computer today has very little in common with the software in the 1A. The upgrade to the helicopter’s mission computer software has improved the display of mission data to the pilot and the weapons system operator (WSO). There are also a host of smaller modifications to the mission systems to add functionality.”
The software for the Automated Flight Control System (AFCS) has also been upgraded. In addition to providing basic stability augmentation, the AFCS can also operate in what are termed higher modes, allowing the helicopter to hover automatic- ally, keep flying at certain altitudes automatically, and, in navigation mode, to automatically follow a prescribed route as well as orientating the aircraft to a target as directed by the main sighting system.
The navigation computer is a hybridised system, using both Global Positioning System and Inertial Navigation System inputs. Radio navigation equipment has also been added and a new communications system fitted.
The weapons computers enable the operation of the Rooivalk’s weapons systems, currently composed of the movable 20 mm cannon under the forward fuselage and unguided rockets carried in pods under the stub wings. “There were significant changes made to the cannon system to improve its reliability as well as its accuracy,” he reports. “There were also changes made to the rocket system, mainly to improve accuracy.”
The helicopter can also carry and fire the Denel Dynamics Mokopa air-to- surface guided missile (originally intended to be an antitank missile but now adapted to be of wider use), but is not yet cleared to employ it operationally. However, it will not be difficult to obtain such clearance.
The helicopter is fitted with an electro- optical sight system which incorporates a TV sensor and a forward looking infrared system – giving both day and night capabilities – as well as a laser rangefinder and designator.
Both the pilot and WSO have helmet-mounted sights, allowing the pilot, if required, to also fire the cannon and rockets. “On the main sighting system there have been hardware and software modifications to improve its reliability. The Rooivalk is not equipped with a fire control radar,” says Van Rooyen, unlike the AH-64D Apache and the Tiger.
For self defence, the Rooivalk is fitted with infrared (IR) heat suppressors on the engine exhausts and with chaff (radar jamming material) and flare (to distract IR homing missiles) dispensers. But to use its chaff and flares with maximum efficiency, the aircraft needs to know if it is being scanned by radar or by laser systems, so it is also fitted with the necessary sensors.
Mechanical Makeover
The Rooivalk retains its original engines, each helicopter being powered by two Makila 1K2 engines from French company Turbomeca, part of the Safran group (Denel Oryx transport helicopters are each powered by two Makila 1A1 engines). “The big difference between these two engines is that the 1K2 offers increased survivability because it has a 30 second supercontingency rating. This means it can deliver a extra power boost should the other engine fail,” he explains.
Of course, the power of the engines has to be conducted to both the main and tail rotors.
The engines are connected through Bendix-type driveshafts to coupling gearboxes which are, in turn, connected to the main gearbox which directly drives the main rotor and, through the tail rotor driveshaft, the tail rotor as well.
“We have changed the mounting mechanism of the coupling gearboxes to improve their resilience to high vibration,” he highlights. “We’ve also incorporated a different strategy of vibration clearance for the transmission system. On most helicopters, you need to do this clearance after every 25 flying hours. What we’ve done is to relocate the measurement positions of the accelerometers to where they can give a more reliable representation of the vibration that the Bendix drive- shafts are subjected to. Vibration on helicopters is your enemy. You have to find strategies for living with it. And vibration was a concern on the Rooivalk. But now, it’s fine. We’ve accumulated quite a significant number of flying hours now with these new modifications and they live up to expectations. We will certainly keep an eye on it, but I am satisfied with what has been done.”
Significant changes have also been made to the fuel transfer system. In addition to its obvious function of pumping fuel from the tanks to the engines, the fuel transfer system also has an important role in maintaining the stability of the helicopter in flight. If all the fuel is drained from one tank, while the other two remain full, it could upset the balance of the flying aircraft.
Each of the three fuel tanks has its own pump. Should one of these fail, the fuel transfer system means that the fuel in that tank can be redistributed to the two other tanks and then fed to the engines. Previously, the fuel transfer system was entirely automatic, but now the system has an override which allows the pilot, in an emergency, to decide on the distribution of the fuel.
Another important addition is a cross-feed system. The fuel is fed to the engines by two boost pumps. Should one of these fail, the cross-feed allows the remaining boost pump to supply fuel to both engines.
“We’ve upgraded the cockpit environmental control system. It’s a very significant upgrade to enable the recirculation of the air. The cooling capacity has been increased by enlarging the evaporators,” he says. “The fact that the evaporators have been increased means that we can remove more humidity from the air coming into the cockpit. This requirement was driven by the need to be able to deploy the aircraft in countries with high humidity, as in central Africa.” The heating system, which bleeds hot air from one of the compressor stages in one of the engines, has also been adjusted to optimise it for South Africa’s often chilly winter con- ditions.
The Rooivalk’s landing gear is unmodified. The main landing gear was developed and manufactured in France to South African specifications, while the tail landing gear was designed, developed and manufactured in South Africa by Denel.
The rotor blades, part of the main gearbox and part of the tail gearbox (including two bevel gears) are of French design but manufactured in South Africa under licence by Denel Aviation. The rotor head, however, is made in France. The driveshaft for the tail rotor was designed and manufactured in South Africa.
Revivified Raptor
“All these aircraft have been test-fired – they went to a weapons range near Bloemfontein, they did some firings, everything is checked, everything is 100%,” enthuses Lt-Gen Gagiano. “They are fully, fully operational in the rocket and gun environment. What we haven’t got yet is the Mokopa missile, which was test-fired at AFB Overberg some time ago and with very good results. So now, if at any time we need a missile, we can just buy [the Mokopa] and just put it on the aircraft.”
The SAAF will now, if called upon, be able to use the Rooivalk to support United Nations (UN) peace missions in Africa. Since at least 2008, there have been a number of times when attack helicopters attached to UN forces have carried out combat missions, most recently in Côte d’Ivoire in April this year.
The delivery of the second and final batch of six Rooivalk Mk 1s will not end Denel’s involvement with the aircraft. “We will continue to support the aircraft, continue to do the maintenance, repair and overhaul activities,” points out Kgobe. “We will continue to provide the engineering support to ensure that the system is airworthy. We will be responsible for the airworthiness of the aircraft. We will continue to advise the Air Force in terms of some of the engineering activities, such as obsolescence studies, and so forth. And, if we have to, we could build more Rooivalks.”
After 25 years, fully operational Rooivalk attack helicopter has been delivered. Could it herald a rebirth?
Six more will follow by the end of this year. All 11 of the upgraded Rooivalks – the aircraft is now formally designated as the Rooivalk Mk 1 and officially categorised as a combat support helicopter – will be operated by 16 Squadron based at Air Force Base (AFB) Bloemspruit, near Bloemfontein, in the Free State province.
The April 1 function also marked the official award of type certification to the Rooivalk (which translates into English as ‘kestrel’
. Type certification proves that the aircraft is airworthy, safe to operate and complies will all relevant regulations.The double event was celebrated by the manufacturer, Denel Aviation. “I think it’s a major milestone,” says Denel Aviation CEO Mike Kgobe. “And we are very proud of it. The aircraft is qualified to international standards. It really is an achievement. I think it also is an indication of the capability of South Africa, because while Denel Aviation was the lead partner there were subsystem manufacturers behind Denel Aviation. So, it shows the capability of South Africa.”
Growing Pains
There can be no doubt that the image of the Rooivalk has suffered as a result of misleading and exaggerated official propaganda in the early years of the programme. The helicopter was conceived in 1985 and the first prototype made its maiden flight in February 1990. South Africans were told that it was a world beater, the best attack helicopter in the world, better than America’s Boeing AH-64 Apache. In reality, the Rooivalk was an experimental aircraft with enormous potential, but very far from being an operational attack helicopter.
The development of the Rooivalk proved to be technically very challenging, and budget cuts only compounded the problems. The original plan to build 36 production aircraft (plus the four prototypes) was abandoned and, in the end, only 12 were built, with the first of these production aircraft making its first public flight (not its maiden flight) in November 1998. Except that these were not really production aircraft at all – they were more like pre- production versions of an aircraft that was still under development.
Although deliveries began to 16 Squadron in January 1999, the Rooivalk was still far from operational. Basically, it had been issued to the squadron for test purposes. It could fly, and fly impressively (although there were, unbeknown to the public, some safety concerns), but it could not fight.
The huge gap between the original propaganda and the reality undoubtedly led to scepticism and cynicism regarding the Rooivalk programme among Parliamentarians, the press and the public. It also obscured what an impressive technical achievement the Rooivalk is.
While a quarter of a century is a long time, it is by no means unparalleled in the annals of the development of complex aircraft. Indeed, there is a pretty good parallel – the protracted development of the Eurocopter Tiger attack helicopter.
Originally conceived in 1984 as a Franco-German project, the Eurocopter Tiger programme has also been dogged by budget cuts and technical problems. The programme had to be relaunched in 1987, the first prototype flew in 1991 but the production contract was only signed in 1999.
While the simpler French combat support (escort/fire support) version entered service in 2005 and was first deployed on operations in Afghanistan in 2009, the more complex German (multirole/antitank) version suffered further delays and the German Army only began to receive operationally capable helicopters in late 2010, instead of the originally scheduled 1992. (The prototype of the multirole/antitank version for France and Spain, which differs from the German aircraft, first flew in 2007 and the first production examples are due for delivery early next year.)
New Bird under the Plumage
When originally assigned to 16 Squadron for testing, the Rooivalks were categorised as being Block 1A aircraft. They were subsequently modified to Block 1B status, and later still to Block 1E.
“We’ve made 130 modifications to the aircraft to take it from Block 1E to Mark 1, plus nine modifications to the ground support equipment,” reveals Denel Aviation Rooivalk Chief Design Engineer Dr Renier van Rooyen, who has been working on the Rooivalk programme since the middle of 1984 and has held his current post since 2003. “For example, the software in the mission computer today has very little in common with the software in the 1A. The upgrade to the helicopter’s mission computer software has improved the display of mission data to the pilot and the weapons system operator (WSO). There are also a host of smaller modifications to the mission systems to add functionality.”
The software for the Automated Flight Control System (AFCS) has also been upgraded. In addition to providing basic stability augmentation, the AFCS can also operate in what are termed higher modes, allowing the helicopter to hover automatic- ally, keep flying at certain altitudes automatically, and, in navigation mode, to automatically follow a prescribed route as well as orientating the aircraft to a target as directed by the main sighting system.
The navigation computer is a hybridised system, using both Global Positioning System and Inertial Navigation System inputs. Radio navigation equipment has also been added and a new communications system fitted.
The weapons computers enable the operation of the Rooivalk’s weapons systems, currently composed of the movable 20 mm cannon under the forward fuselage and unguided rockets carried in pods under the stub wings. “There were significant changes made to the cannon system to improve its reliability as well as its accuracy,” he reports. “There were also changes made to the rocket system, mainly to improve accuracy.”
The helicopter can also carry and fire the Denel Dynamics Mokopa air-to- surface guided missile (originally intended to be an antitank missile but now adapted to be of wider use), but is not yet cleared to employ it operationally. However, it will not be difficult to obtain such clearance.
The helicopter is fitted with an electro- optical sight system which incorporates a TV sensor and a forward looking infrared system – giving both day and night capabilities – as well as a laser rangefinder and designator.
Both the pilot and WSO have helmet-mounted sights, allowing the pilot, if required, to also fire the cannon and rockets. “On the main sighting system there have been hardware and software modifications to improve its reliability. The Rooivalk is not equipped with a fire control radar,” says Van Rooyen, unlike the AH-64D Apache and the Tiger.
For self defence, the Rooivalk is fitted with infrared (IR) heat suppressors on the engine exhausts and with chaff (radar jamming material) and flare (to distract IR homing missiles) dispensers. But to use its chaff and flares with maximum efficiency, the aircraft needs to know if it is being scanned by radar or by laser systems, so it is also fitted with the necessary sensors.
Mechanical Makeover
The Rooivalk retains its original engines, each helicopter being powered by two Makila 1K2 engines from French company Turbomeca, part of the Safran group (Denel Oryx transport helicopters are each powered by two Makila 1A1 engines). “The big difference between these two engines is that the 1K2 offers increased survivability because it has a 30 second supercontingency rating. This means it can deliver a extra power boost should the other engine fail,” he explains.
Of course, the power of the engines has to be conducted to both the main and tail rotors.
The engines are connected through Bendix-type driveshafts to coupling gearboxes which are, in turn, connected to the main gearbox which directly drives the main rotor and, through the tail rotor driveshaft, the tail rotor as well.
“We have changed the mounting mechanism of the coupling gearboxes to improve their resilience to high vibration,” he highlights. “We’ve also incorporated a different strategy of vibration clearance for the transmission system. On most helicopters, you need to do this clearance after every 25 flying hours. What we’ve done is to relocate the measurement positions of the accelerometers to where they can give a more reliable representation of the vibration that the Bendix drive- shafts are subjected to. Vibration on helicopters is your enemy. You have to find strategies for living with it. And vibration was a concern on the Rooivalk. But now, it’s fine. We’ve accumulated quite a significant number of flying hours now with these new modifications and they live up to expectations. We will certainly keep an eye on it, but I am satisfied with what has been done.”
Significant changes have also been made to the fuel transfer system. In addition to its obvious function of pumping fuel from the tanks to the engines, the fuel transfer system also has an important role in maintaining the stability of the helicopter in flight. If all the fuel is drained from one tank, while the other two remain full, it could upset the balance of the flying aircraft.
Each of the three fuel tanks has its own pump. Should one of these fail, the fuel transfer system means that the fuel in that tank can be redistributed to the two other tanks and then fed to the engines. Previously, the fuel transfer system was entirely automatic, but now the system has an override which allows the pilot, in an emergency, to decide on the distribution of the fuel.
Another important addition is a cross-feed system. The fuel is fed to the engines by two boost pumps. Should one of these fail, the cross-feed allows the remaining boost pump to supply fuel to both engines.
“We’ve upgraded the cockpit environmental control system. It’s a very significant upgrade to enable the recirculation of the air. The cooling capacity has been increased by enlarging the evaporators,” he says. “The fact that the evaporators have been increased means that we can remove more humidity from the air coming into the cockpit. This requirement was driven by the need to be able to deploy the aircraft in countries with high humidity, as in central Africa.” The heating system, which bleeds hot air from one of the compressor stages in one of the engines, has also been adjusted to optimise it for South Africa’s often chilly winter con- ditions.
The Rooivalk’s landing gear is unmodified. The main landing gear was developed and manufactured in France to South African specifications, while the tail landing gear was designed, developed and manufactured in South Africa by Denel.
The rotor blades, part of the main gearbox and part of the tail gearbox (including two bevel gears) are of French design but manufactured in South Africa under licence by Denel Aviation. The rotor head, however, is made in France. The driveshaft for the tail rotor was designed and manufactured in South Africa.
Revivified Raptor
“All these aircraft have been test-fired – they went to a weapons range near Bloemfontein, they did some firings, everything is checked, everything is 100%,” enthuses Lt-Gen Gagiano. “They are fully, fully operational in the rocket and gun environment. What we haven’t got yet is the Mokopa missile, which was test-fired at AFB Overberg some time ago and with very good results. So now, if at any time we need a missile, we can just buy [the Mokopa] and just put it on the aircraft.”
The SAAF will now, if called upon, be able to use the Rooivalk to support United Nations (UN) peace missions in Africa. Since at least 2008, there have been a number of times when attack helicopters attached to UN forces have carried out combat missions, most recently in Côte d’Ivoire in April this year.
The delivery of the second and final batch of six Rooivalk Mk 1s will not end Denel’s involvement with the aircraft. “We will continue to support the aircraft, continue to do the maintenance, repair and overhaul activities,” points out Kgobe. “We will continue to provide the engineering support to ensure that the system is airworthy. We will be responsible for the airworthiness of the aircraft. We will continue to advise the Air Force in terms of some of the engineering activities, such as obsolescence studies, and so forth. And, if we have to, we could build more Rooivalks.”
After 25 years, fully operational Rooivalk attack helicopter has been delivered. Could it herald a rebirth?
Last edited by a moderator:
