Chinook & other tandem rotors discussions
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Also reported by the Beeb, for those without a subscription to The Times: Blunders lead to helo shortage. No sign of the report on the NAO website yet.
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£260m SAS helicopters can't fly with a cloud in the sky
By Michael Smith, Defence Correspondent
(Filed: 07/04/2004)
Eight special forces helicopters delivered to the Ministry of Defence in 2001 at a cost of nearly £260 million have not been used in Afghanistan or Iraq because they cannot fly if it is cloudy.
The first SAS team to enter Afghanistan was delayed by six days because of the problems with the Chinooks, which are allowed to fly above 500ft only in clear skies.
£127 million must be spent so the Chinook can carry out the missions they were bought for
The problems, disclosed today in a National Audit Office report, were the result of "one of the most incompetent procurements of all time", Edward Leigh, the chairman of the Commons public accounts committee said yesterday.
"Eight brand new Chinook HC3s costing £259 million were delivered in 2001 but will be sitting on the ground until 2007," he said. "Because of a massively botched job, they cannot be flown when there is a cloud in the sky. The MoD might as well have bought eight turkeys."
In what Mr Leigh described as "an atrocious oversight", the ministry had decided to cut costs by refusing to pay for a fully digital cockpit. The result was a compromise that did not match British defence safety standards.
The 500ft restriction means that the helicopters "cannot be used other than for limited flight trials", the report says.
It will take £127 million more to bring them up to British standards and enable them to carry out the tasks for which they are needed.
The helicopters were ordered from Boeing in 1995. They were tailored to the needs of the SAS and Special Boat Service, with satellite communications technology, extra fuel tanks and in-flight refuelling probes for long flights.
At the start of the war in Afghanistan, when there was no moon - in theory the best conditions for a special forces insertion - the SAS could not move because its Chinook pilots relied on light-enhancing night vision goggles.
As a result, the troops were unable to fly into Afghanistan until six days after their American counterparts.
The report is also critical of the ministry for the failure to provide enough helicopters to carry troops into action. It says: "There is an overall deficit of 38 per cent in helicopter lift. There is also an 87 per cent shortfall in ship-optimised helicopter lift."
The criticism coincides with proposals from MoD working groups to axe all RAF Puma and all Royal Navy Sea King helicopters as part of a drive to save £1.2 billion from this year's defence budget. But the Merlin helicopters that would take over responsibility for airlifting troops into operations are "restricted to essential flying" because of a suspected tail rotor fault.
The report recommends that the Royal Navy and the RAF follow the Army Air Corps in using senior NCOs to fly aircraft rather than confining the role to commissioned officers.
"one of the most incompetent procurements of all time"
By Michael Smith, Defence Correspondent
(Filed: 07/04/2004)
Eight special forces helicopters delivered to the Ministry of Defence in 2001 at a cost of nearly £260 million have not been used in Afghanistan or Iraq because they cannot fly if it is cloudy.
The first SAS team to enter Afghanistan was delayed by six days because of the problems with the Chinooks, which are allowed to fly above 500ft only in clear skies.
£127 million must be spent so the Chinook can carry out the missions they were bought for
The problems, disclosed today in a National Audit Office report, were the result of "one of the most incompetent procurements of all time", Edward Leigh, the chairman of the Commons public accounts committee said yesterday.
"Eight brand new Chinook HC3s costing £259 million were delivered in 2001 but will be sitting on the ground until 2007," he said. "Because of a massively botched job, they cannot be flown when there is a cloud in the sky. The MoD might as well have bought eight turkeys."
In what Mr Leigh described as "an atrocious oversight", the ministry had decided to cut costs by refusing to pay for a fully digital cockpit. The result was a compromise that did not match British defence safety standards.
The 500ft restriction means that the helicopters "cannot be used other than for limited flight trials", the report says.
It will take £127 million more to bring them up to British standards and enable them to carry out the tasks for which they are needed.
The helicopters were ordered from Boeing in 1995. They were tailored to the needs of the SAS and Special Boat Service, with satellite communications technology, extra fuel tanks and in-flight refuelling probes for long flights.
At the start of the war in Afghanistan, when there was no moon - in theory the best conditions for a special forces insertion - the SAS could not move because its Chinook pilots relied on light-enhancing night vision goggles.
As a result, the troops were unable to fly into Afghanistan until six days after their American counterparts.
The report is also critical of the ministry for the failure to provide enough helicopters to carry troops into action. It says: "There is an overall deficit of 38 per cent in helicopter lift. There is also an 87 per cent shortfall in ship-optimised helicopter lift."
The criticism coincides with proposals from MoD working groups to axe all RAF Puma and all Royal Navy Sea King helicopters as part of a drive to save £1.2 billion from this year's defence budget. But the Merlin helicopters that would take over responsibility for airlifting troops into operations are "restricted to essential flying" because of a suspected tail rotor fault.
The report recommends that the Royal Navy and the RAF follow the Army Air Corps in using senior NCOs to fly aircraft rather than confining the role to commissioned officers.
"one of the most incompetent procurements of all time"
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The report recommends that the Royal Navy and the RAF follow the Army Air Corps in using senior NCOs to fly aircraft rather than confining the role to commissioned officers.
Perhaps,
But totally irrelevant to the topic. Yet again a cash strapped MoD has made a total bolleaux of a new aircraft project - but the government will seek to blame anyone other than themselves.
THe root cause is having people like Blar, Hoon and Gordon-the-greedy in power.
How much does the nation waste on paying econmic migrants with their ever outstretched hands? And how much do Trust-me-Tone's bring-a-bottle wars cost the nation?
And we can't even afford 8 helicopters! E I G H T !!
But I supose if the RAF can't even afford to buy its own basic trainers or ME training aeroplanes anymore, the fact that we can't afford a few helicopters shouldn't come as a huge surprise....
How did it ever get into such a state?
But totally irrelevant to the topic. Yet again a cash strapped MoD has made a total bolleaux of a new aircraft project - but the government will seek to blame anyone other than themselves.
THe root cause is having people like Blar, Hoon and Gordon-the-greedy in power.
How much does the nation waste on paying econmic migrants with their ever outstretched hands? And how much do Trust-me-Tone's bring-a-bottle wars cost the nation?
And we can't even afford 8 helicopters! E I G H T !!
But I supose if the RAF can't even afford to buy its own basic trainers or ME training aeroplanes anymore, the fact that we can't afford a few helicopters shouldn't come as a huge surprise....
How did it ever get into such a state?
Ecce Homo! Loquitur...
Full Report (989K). Executive Summary (140K).
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WHO ORDERED THE CHNOOKS?
Beags,
On Radio 4 interview with Minister for Def Procurement this morning as I drove to work he said that the contract was let in 1995. Therefore it was the Tory Band that were playing and not the Socialists.
What gets no mention at all, and maybe I'm jumping to conclusions here, is that the contract was changed/amended after it was let.
That would be another story and something which the uniformed members of the MOD are often guilty of.
Low Ball
On Radio 4 interview with Minister for Def Procurement this morning as I drove to work he said that the contract was let in 1995. Therefore it was the Tory Band that were playing and not the Socialists.
What gets no mention at all, and maybe I'm jumping to conclusions here, is that the contract was changed/amended after it was let.
That would be another story and something which the uniformed members of the MOD are often guilty of.
Low Ball
From the report:
Flawed procurement of eight Chinook HC3 helicopters means that, although they were delivered to specification by the contractor in December 2001, they cannot yet be used operationally, principally because there is insufficient evidence to demonstrate that the avionics software meets United Kingdom Defence standards. This is primarily because the programme was not de-risked prior to investment decisions being taken; nor did the contract specify that the software should be analysed in accordance with United Kingdom Defence standards. Other user requirements categorised as essential have not been delivered because, for a variety of reasons, they too were not included in the contract. To bring the helicopters broadly up to the standard of the existing Chinook fleet would require approximately £127 million, over and above the £259 million originally estimated, and would mean the helicopter would enter service in mid-2007 - some nine years later than the original In-Service Date, although this latter was re-defined in March 1998 to June 2002.
The shortfall in battlefield helicopter capability will continue
Even if improvements to efficiency and effectiveness are made, there will still be a shortfall in helicopter capability. A recent Departmental study concluded that there is currently a 38 per cent shortfall in overall battlefield support helicopter lift, which includes an 87 per cent shortfall in ship-optimised support helicopter lift. Primarily, the latter deficit is a manifestation of a changed strategic environment over the past decade, which has generated a greater requirement to undertake littoral operations. According to the Department, the shortfall in ship-optimised lift will remain until 2018, while overall battlefield lift will remain inadequate until 2017.
In addition, the nature of the legacy fleet means that many platforms are not fully equipped to undertake missions in certain operational and environmental conditions, including those recently experienced in Afghanistan and Iraq. The helicopter force has a number of critical capability shortfalls, some of which can only be addressed by expensive modifications. Owing principally to a lack of resources, these capability shortfalls are often met by Urgent Operational Requirements. For example, part of the current Chinook fleet has acquired the necessary capabilities to meet operational demands. However, this process has often not only been costly but it is essentially short-term in nature.
Flawed procurement of eight Chinook HC3 helicopters means that, although they were delivered to specification by the contractor in December 2001, they cannot yet be used operationally, principally because there is insufficient evidence to demonstrate that the avionics software meets United Kingdom Defence standards. This is primarily because the programme was not de-risked prior to investment decisions being taken; nor did the contract specify that the software should be analysed in accordance with United Kingdom Defence standards. Other user requirements categorised as essential have not been delivered because, for a variety of reasons, they too were not included in the contract. To bring the helicopters broadly up to the standard of the existing Chinook fleet would require approximately £127 million, over and above the £259 million originally estimated, and would mean the helicopter would enter service in mid-2007 - some nine years later than the original In-Service Date, although this latter was re-defined in March 1998 to June 2002.
The shortfall in battlefield helicopter capability will continue
Even if improvements to efficiency and effectiveness are made, there will still be a shortfall in helicopter capability. A recent Departmental study concluded that there is currently a 38 per cent shortfall in overall battlefield support helicopter lift, which includes an 87 per cent shortfall in ship-optimised support helicopter lift. Primarily, the latter deficit is a manifestation of a changed strategic environment over the past decade, which has generated a greater requirement to undertake littoral operations. According to the Department, the shortfall in ship-optimised lift will remain until 2018, while overall battlefield lift will remain inadequate until 2017.
In addition, the nature of the legacy fleet means that many platforms are not fully equipped to undertake missions in certain operational and environmental conditions, including those recently experienced in Afghanistan and Iraq. The helicopter force has a number of critical capability shortfalls, some of which can only be addressed by expensive modifications. Owing principally to a lack of resources, these capability shortfalls are often met by Urgent Operational Requirements. For example, part of the current Chinook fleet has acquired the necessary capabilities to meet operational demands. However, this process has often not only been costly but it is essentially short-term in nature.
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Chinook shortage
Chinook blunder 'left RAF short'
The Chinooks were meant to be in service in 1998
Eight new helicopters worth £259m are grounded due to a "botched" procurement, a study by the National Audit Office has said.
more at
http://news.bbc.co.uk/1/hi/uk/3606325.stm
The Chinooks were meant to be in service in 1998
Eight new helicopters worth £259m are grounded due to a "botched" procurement, a study by the National Audit Office has said.
more at
http://news.bbc.co.uk/1/hi/uk/3606325.stm
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Were these the aircraft that were bought as "stocking fillers" - ie, late purchases to soak up an unexpected budget surplus? Did some blokes from OR and PE literally fly into Seattle waving cheque books? Did Boeing's sell any more aircraft to this standard to any other customers? If so, are they accepting the same operating restrictions, or are Boscombe and PE over-egging their standards? It would not be the first time THAT has happened. It was amazing during the "Malvinas Arse-kicking" who many radical mods and capabilities were cleared by Boscombe in short order because it was also a "PE Arse-kicking" exercise. 
Perhaps I'm missing something here? So the HC3 is limited to day/night VMC only. Isn't that what most of you do anyway? The 500' restriction seems strange, as you're looking out below that height anyway, so the lack of IF capability hardly seems relevant.
Surely the aircraft should be able to carry out most of the missions that the rest can do at present.
Surely the aircraft should be able to carry out most of the missions that the rest can do at present.
Since there is no suitable tanker available for SF ops as well, why has`nt that problem been addressed?
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Tandem Rotor Questions
Ive been doing some reading lately, mainly from Proutys and Johnstones books.
In reading about tandem helicopters I was struck by a few of things.
1, Longitudinal control of the helo is acheived by differential collective, does this mean that there is no longitudinal cyclic control? Or is there some and its used for trimming the helo?
2, Why are the tandems so quick? Considering they are of an older design yet can cruise at 150knts. Is it due to the large amount of horse power installed? Or because retreating blade stall isnt as important with two advancing blades.
3, has anyone, or do you know anyone who has had the rear rotor go through ETL while doing a turn about the nose? Is this very severe when it happens, or relatively controlable?
One more, when picking up to the hover, in nil wind, do you have to make any corrections, I understand the torque will be canelled out, Im just wondering if there is any other cross coupling due to the seperation of the rotors.
Thanx in advance
In reading about tandem helicopters I was struck by a few of things.
1, Longitudinal control of the helo is acheived by differential collective, does this mean that there is no longitudinal cyclic control? Or is there some and its used for trimming the helo?
2, Why are the tandems so quick? Considering they are of an older design yet can cruise at 150knts. Is it due to the large amount of horse power installed? Or because retreating blade stall isnt as important with two advancing blades.
3, has anyone, or do you know anyone who has had the rear rotor go through ETL while doing a turn about the nose? Is this very severe when it happens, or relatively controlable?
One more, when picking up to the hover, in nil wind, do you have to make any corrections, I understand the torque will be canelled out, Im just wondering if there is any other cross coupling due to the seperation of the rotors.
Thanx in advance
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Dave Jackson's your man on this topic. However if you look back in the Forum you will probably find all the answers. Just look for DJ and somewhere is the info. Sorry I am so vague but I don't have time to look back for the precise locations.
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I can answer one of your questions.
To: Spaced
When you go into a hover the pitch on both rotors is the same. When you push forward cyclic the front rotor decreases in pitch and the rear rotor increases pitch. Upon reaching a forward speed of around 60 knots there is an automatic system that inputs forward cyclic and at this time the pilot can decrease his collective input.
I think.
1, Longitudinal control of the helo is acheived by differential collective, does this mean that there is no longitudinal cyclic control? Or is there some and its used for trimming the helo?
I think.
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Longitudinal control is through a combination of differential collective and tilting of the main rotor heads by the Automatic Flight Control System.
One of the features (and probably a reason why the Chinook is so speedy) is that the fuselage is pretty well level throughout the flight envelope - there isn't the nose-down tilt that single rotor helicopters have. As airspeed increases, the AFCS tilts the two swashplates by electric motors - this system is called Longitudinal Cyclic Trim (LCT). The mechanical control system only has two actuators (for collective and roll control).
When you move the cyclic fore-aft, it does introduce differential collective pitch, but as the airspeed changes the LCTs program to take out some of the differential collective effect.
The AFCS is incredibly complicated, and incorporates Differential Airspeed Hold (DASH) actuators to require the cyclic to move forward with increasing airspeed (basically to keep the pilot happy - more forward stick is needed with airspeed is the natural thing).
They are quick because of incredible amounts of power, and reasonably streamlined fuselages.
You'd have to do a really fast turn to generate translational lift on the outside rotor - and the AFCS does a remarkable job of maintaining the attitude constant without the pilot, so the effect would be masked as far as the pilot was concerned anyway (turn the AFCS off and you'd see it).
Hope that helps.
One of the features (and probably a reason why the Chinook is so speedy) is that the fuselage is pretty well level throughout the flight envelope - there isn't the nose-down tilt that single rotor helicopters have. As airspeed increases, the AFCS tilts the two swashplates by electric motors - this system is called Longitudinal Cyclic Trim (LCT). The mechanical control system only has two actuators (for collective and roll control).
When you move the cyclic fore-aft, it does introduce differential collective pitch, but as the airspeed changes the LCTs program to take out some of the differential collective effect.
The AFCS is incredibly complicated, and incorporates Differential Airspeed Hold (DASH) actuators to require the cyclic to move forward with increasing airspeed (basically to keep the pilot happy - more forward stick is needed with airspeed is the natural thing).
They are quick because of incredible amounts of power, and reasonably streamlined fuselages.
You'd have to do a really fast turn to generate translational lift on the outside rotor - and the AFCS does a remarkable job of maintaining the attitude constant without the pilot, so the effect would be masked as far as the pilot was concerned anyway (turn the AFCS off and you'd see it).
Hope that helps.
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Shawn is correct regarding systems on the Chinook, and perhaps other tandems. They can be flown without LCT, DASH, AFCS, and DCPT (Differential Collective Pitch Trim). All those devices are made to reduce pilot workload, make flight more comfortable, and expand the flight envelope.
1. Longitudinal cyclic only controls differential collective pitch. Any fore and aft tilting of the disc is controlled with speed sensors and cockpit switches.
2. Retreating blade stall is important in tandems. I think part of the reason for the increased speed is a lower tip speed is possible due to having a larger rotor area for the same rotor diameter (because there are two circles).
The speed limit is normally imposed by loads on the necessarily large aft mast. These are reduced by tilting the disk forward with the LCT.
3. As Shawn mentioned, the turn rate required would be rather uncomfortable. Also, in a turn the blades wouldn't experience ETL at the same time, so I'd expect unusual flight characteristics to appear before fully realizing ETL. The sidewards flight limit we had would have kept you below ETL.
I haven't flown a tandem with an AFCS, just a rate damping SAS. The SAS would not have hidden these effects. SAS (or AFCS) off flight is very possible but does require a much higher workload. To realize what is happening in tandem rotor flight I think SAS off flight is required. The higher lift on the aft rotor makes it want to go faster than the forward rotor, resulting in yaw instability (divergent). Typical roll control but very rapid pitch rates will occur for small inputs.
4. When picking up into the hover, the only change from tail rotor flight is that you don't have to change pedal based on power. There is still the requirement to finely adjust all four axes together, resulting in a similiar workload. The SAS or AFCS lowers the workload vice the tandem rotor configuration. I'd expect most experienced pilots will have fully adapted to a new configuration before 200 hours on type or less (going t/r to tandem or tandem to t/r).
1. Longitudinal cyclic only controls differential collective pitch. Any fore and aft tilting of the disc is controlled with speed sensors and cockpit switches.
2. Retreating blade stall is important in tandems. I think part of the reason for the increased speed is a lower tip speed is possible due to having a larger rotor area for the same rotor diameter (because there are two circles).
The speed limit is normally imposed by loads on the necessarily large aft mast. These are reduced by tilting the disk forward with the LCT.
3. As Shawn mentioned, the turn rate required would be rather uncomfortable. Also, in a turn the blades wouldn't experience ETL at the same time, so I'd expect unusual flight characteristics to appear before fully realizing ETL. The sidewards flight limit we had would have kept you below ETL.
I haven't flown a tandem with an AFCS, just a rate damping SAS. The SAS would not have hidden these effects. SAS (or AFCS) off flight is very possible but does require a much higher workload. To realize what is happening in tandem rotor flight I think SAS off flight is required. The higher lift on the aft rotor makes it want to go faster than the forward rotor, resulting in yaw instability (divergent). Typical roll control but very rapid pitch rates will occur for small inputs.
4. When picking up into the hover, the only change from tail rotor flight is that you don't have to change pedal based on power. There is still the requirement to finely adjust all four axes together, resulting in a similiar workload. The SAS or AFCS lowers the workload vice the tandem rotor configuration. I'd expect most experienced pilots will have fully adapted to a new configuration before 200 hours on type or less (going t/r to tandem or tandem to t/r).