When you read about the Eurofighter Typhoon you will read about Tranches, Blocks, Phase Enhancements, Change Proposals but what does it all mean?
To understand the Typhoon programme you have to first look at a brief history of Typhoon.
In 1979 British Aerospace and Messerschmitt-Bolkow-Blohm produced a proposal to meet the needs of both the British RAF and West German Luftwaffe for a Cold War air supremacy fighter.
Between 1979 and 1986 (when the first prototype took to the air) the partner nations tried to reach agreement over specification, requirements and how to approach the project. This saw the name of the project change names from European Combat Fighter to European Combat Aircraft to Agile Combat Aircraft to Future European Fighter Aircraft to finally being called European Fighter Aircraft.
The programme would see the Italians along with the Spanish join and the French join then leave, twice!
The 1990s saw arguments, politics and negotiation around the radar supplier and how the work should be shared between the four countries. With the Berlin Wall coming down, the end of the Cold War and the scaling back of defence budgets the partner nations reduced the number of aircraft they would commit to.
The Germans would make the biggest cut, reducing the number from 250 down to 140 before raising it to 180 after lengthy negotiation to limit the associated impact to their share of the industrial contracts to build the aircraft.
Further delays to the project would occur in the late 90s when the Germans still struggling with the cost of the reunification would delay making their payment for the construction stage phase, putting back the project by a year.
Type acceptance for Typhoon finally came on 30th June 2003 four year after originally planned.
The first delivery was made to the German Luftwaffe on 4th August 2003.
With a number of different nations involved in a project as large as this, all with an equal say there was always going to be disagreement, delays and a lot of politics. In attempt to make reaching agreement easier Typhoon would be produced in three tranches.
Each tranche is a separate contract between the partner nations and Eurofighter GmbH for an agreed number of aircraft. This would allow the partner nations the flexibility to change the number of aircraft they order over the construction period but at the cost of having to pay compensation to Eurofighter GmbH if reducing the number to assure construction and development continues without an increase to the unit price for the other partner nations.
Whilst the three tranches are financial divisions it also allows specification change to the aircraft from the framework laid out at the start. This would allow new features to be added or deleted as required even at an individual nation level.
Eurofighter Typhoon Trance 1 Block 1
Where the tranche is a financial division, the block is a level of capability. With each new block new capabilities are introduced. The block approach is a common method used for military aircraft to roll out hardware upgrade, software upgrade, new hardware and / or structure change.
Typhoon was originally planned to have three blocks per tranche (with Tranche 3 containing Block 20, Block 25 and an option for another block). Each block was to build on the previous one with Tranche 1 covering air-to-air capabilities, Tranche 2 to introduce new weapons such as the Meteor BVR missile and Tranche 3 for future capabilities such as the AESA radar and thrust vectoring.
The development plan was at Block 5 (the final block in Tranche 1) Typhoon would be at Full Operational Capability (FOC). By Block 10 (the penultimate block in Tranche 2) it would be Enhanced Operational Capability 1 (EOC-1) and Block 15 (the final block in Tranche 2) it would be EOC-2. The development plan for Block 20 / Block 25 in Tranche 3 was to be left open.
The plan was drawn up in the Cold War when Typhoon was intended to be used as an air supremacy fighter operating over Western Europe fighting against Soviet MiGs and Sukhois. With the fall of the Soviet Union this threat was no longer present and new requirements in Iraq and Afghanistan had replaced it which needed an air-to-ground capability.
The defence budgets for the partner nations were still under pressure and justifying all three tranches of Typhoons for air defence was a difficult sell, particularly for the RAF which had plans for 7 squadrons of Typhoons.
Eurofighter Typhoon Trance 1 Block 5
In 2007, the partner nations responded to these two problems with Change Proposal 210 which approved changes to Typhoon to give it an air-to-ground capability. This would change Typhoon from an air supremacy fighter to a swing-role fighter capable of performing both the air-to-air role and air-to-ground role.
CP-210 will be introduced in Tranche 2 and will be retro fitted to Tranche 1 aircraft.
The RAF with Tornado GR4s deployed to Iraq and Harriers deployed to Afghanistan needed Typhoon to have an air-to-ground capability before Tranche 2 started delivery with CP-210. In 2006, under CP-193 an "austere" air-to-ground capability was rapidly developed and deployed to Trance 1 Block 5 Typhoons, referred to as Typhoon FGR4 by the RAF. The austere support provided integration of Litening III, the chosen Laser Designator Pod, and laser guide munitions in the form of Paveway II / Enhanced Paveway II.
This has created a strange situation where Tranche 1 Block 5 aircraft have both air-to-air and limited air-to-ground capability whilst newer Tranche 2 Block 8 aircraft with over 400 improvements only have air-to-air capability.
The crux of the problem is software. The modification to the Typhoons software made by CP-193 was outside the development path. If they continued with two development paths (one with CP-193 for the RAF and one without for the other nations) you would need to develop and flight test both versions of the software with the RAF picking up the bill for the duplication of work.
By getting all nations to agree to include air-to-ground capability (CP-210) the RAF and Eurofighter GmbH had managed to bring this software modification into the main development path of the software but not soon enough to have it include in Block 8.
Eurofighter Typhoon Trance 1 Block 5 with LITENING III pod
With the change to a swing-role fighter the development plan defined in EOC-1 and EOC-2 no longer matched where the development of the aircraft was heading. To this end, both were replaced with Phase 1 Enhancement (P1E) and Phase 2 Enhancement (P2E) respectively.
P1E was signed off in 2007 and contains the CP-210 modification. Flight testing has begun on P1E and it is scheduled to reach service release in 2011.
P2E was very short lived and has now been abandoned and in favour of individual modifications similar to the method used for CP-193 and CP-210. This will allow more granular approach and avoid having to get agreement from all partner nations for a large package of changes.
With features being employed as individually the need for a block with a defined capability no longer existed. Tranche 2 Block 8 / 8B (the current production level) will be the last defined block.
The RAF has committed to have a standardised fleet and the Tranche 1 Typhoons are undergoing R1 and R2 upgrades to retrofit them to the latest build within the tranche.
All Tranche 1 aircraft will be upgraded to Tranche 1 Block 5 with P1E.
All Tranche 2 aircraft will be Block 8 with P1E.
This will give all the aircraft full air-to-air capability, full air-to-ground capability and the ability to perform both these roles simultaneously.
There will be no upgrades from Tranche 1 to Tranche 2 due to the physical differences between the two builds.
Eurofighter Typhoon Trance 2 Block 8
With pressure increasing on defence budgets, especially for the British MoD who had a 36 billion pound funding black hole, Tranche 3 was under a very real threat of being cancelled.
The partner nations, in particular Germany, applied pressure on the British Government to sign the contract but the British insisted that costs must be reduced before they would do that.
To help the situation the tranche was broken into two parts, Tranche 3A and 3B.
A break through was finally made. The British would take their full allocation of 40 Tranche 3A Typhoons in exchange for 900 million pounds worth of savings achieved from reductions to the support contracts by BAE, Rolls-Royce and other partners.
Tranche 3A is due to start being delivered in 2013 and completing in 2016. The exact specification of Tranche 3A isn't known at the time of writing as it is still being negotiated (the Tranche 3A contract signed only agrees to the production of a Tranche 3A not the capability of those aircraft) but it is expected they will be based on Tranche 2 with phased upgrades being included from 2014.
The British MoD has stated that with the signing of the contract for the production of Trance 3A the programme had reached the financial ceiling agreed in the Memorandum of Understanding (MoU) and therefore had no further obligation to purchase their allocation of Tranche 3B Typhoons. Eurofighter GmbH have said this would be a matter for the partner nations to discuss.
Without the British taking their allocation the future of Trance 3B looks bleak but the British haven't totally ruled out making further purchases of Typhoons, instead saying they are unlikely to do so but reverse the right.
Without Tranche 3B to keep the production lines open time is short for Eurofighter GmbH to attract export customers.
An important part of attracting export customers is to adopt cutting edge technology into Typhoon.
The current radar in Typhoon is a mechanical radar that physically moves to scan. Electronically scanning radars are rapidly improving and appears to be the future of radar design.
At present only Britain and Germany are showing interest in having an AESA radar fitted to Typhoon. Tranche 3A aircraft have both the structural, power and cooling requirements to support its addition. Tranche 2 aircraft only have the structural requirements meaning that a retrofit program would be needed to support its addition.
Eurofighter Development Aircraft 5 (DA5) has already flown with an AESA radar in 2007 and it's expected that a test flight program with Salex will start in 2012. Salex are currently developing the AESA radar for the Saab Gripen NG.
Like other fighter aircraft Typhoon is capable of using external (drop) tanks to increase its fuel capacity. These tanks can be fitted to the three wet points located on the fuselage centre point and the middle point on both wings. The addition of these tanks do bring a number of drawbacks. The loss of the two wing points means less points to attach ordinance and the centre point is also used to attach a targeting pod. The tanks also increase drag; although Typhoon is still capable of going supersonic with all three tanks fitted (tested to Mach 1.6 with three 1000 litre tanks).
Conformal Fuel Tanks would offer a solution to this problem with two semi-permanent tanks grafted onto the fuselage, each offering 1500 litres of fuel, without the loss of any points and reduced levels of drag. You will have seen them used on the F-15E Strike Eagle and starting to be seen more commonly on F-16s.
At present only Britain has show interest in having CFTs. BAE have tested a scale model in a wind tunnel and are working on development with GKN Engage.
Eurofighter Typhoon Trance 1 Block 2B with three 1000 litre drop tanks
Thrust Vectoring Control allows the nozzle on the engine to be deflected to enhance the agility of the fighter. With 3D TVC the nozzles are able to move up, down, left and right or a combination e.g. up and left.
No partner nation has expressed an interested in having TVC. Eurojet, the consortium of companies that produces the engines for Typhoon, is hoping to attract support for TVC by concentrating on the benefits provided above the enhanced agility.
Eurojet has said TVC would decrease fuel burn, increase the life of hot running components and reduce take off distance (particularly useful in 'hot and high' environments).
Eurofighter Typhoon Trance 1 Block 5
