Developing new military aircraft is a long, slow process. For example, the RAF’s Tornado jets were first conceived in the 1960s and have now been in service for 35 years. The now retired Harrier Jump Jets have a similar long lifespan. Finding replacements for these ageing designs can be difficult but the decision on where to go has been made rather easier by a decision made in the Usa in the 1980s.

Like many other countries, the USA was seeking a modern replacement for its strike and interceptor aircraft. A contract was awarded to Lockheed Martin to produce an aircraft now known as the F35 "Lightning II". The UK, keen to get its hands on a new aircraft, pitched in to the development stage to the tune of $2.5billion. That sum, important though it was, has been dwarfed by the total development cost which continues to escalate well beyond original projections. The development programme has also fallen well behind the initial schedule. That’s why, when the UK’s new aircraft carrier was launched earlier this year, no F35s were available to do a fly past and the aeroplane proudly on display was a fibre glass mock up. Part of the problem was that the F35s being brought into service in America had suffered a series of engine fires, causing the entire fleet to be grounded.

That’s not an impressive pedigree so far but things could actually be a lot worse as far as the UK is concerned. We’ll try not to make this part too technical but a little understanding of military aviation is required here.

The basic premise behind the F35 was that it should provide three main variants depending on the purpose it is to be used for, with the three variants sharing around 80% of their parts. That sounds eminently sensible unless you appreciate that, in the entire history of military aviation, almost every attempt to design an aircraft which can fulfil a number of different roles results in machines that are not very good in any of those roles.

The F35 concept, however, was to produce three similar planes for use in different scenarios. The F35A, for example, would be the standard, conventional aircraft; the F35B would have Vertical or Short Take Off and Landing capability ("VSTOL") like the Harrier Jump Jets; and the F35C would be designed for use on aircraft carriers.

OK, that sounds reasonably sensible although, again, history shows that variants of one design tend not to be all that great in actual service. Still, one assumes that the US military knows what they are doing, right? After all, the F35 is designed to be state of the art, with a mass of electronics which enable the pilot to hook into nearby defence computers in other aircraft or even in aircraft carriers to provide a local web of tactical information. Thanks to clever cameras and computers, the pilot can even look down and "See through the floor" to see what is below him. The F35, it is claimed, will be several times more effective than current strike or aerial combat machines. Wow. Sounds impressive.

Well, maybe not. Despite these claims, the F35 has come in for a number of criticisms. Here’s a short list of some of the faults that critics have pointed out:

The F35 has poor acceleration.

It cannot carry much of a bomb load because bombs must be carried inside the fuselage to maintain its stealth integrity.

Its wings are too small to allow the sort of manoeuvring required in high speed air combat.

It is overloaded with electronics.

The body has been made so light in order to compensate for the overloading of technical equipment that it is highly vulnerable and liable to fall apart if struck by even machine gun bullets, let alone a missile.

Those are pretty serious faults and it is to be hoped, given that most Western air forces intend to use the F35, that these criticisms are exaggerated.

For the UK, though, the problems don’t stop with the late delivery, cost overruns or alleged performance issues. You see, not only did the UK contribute $2.5billion to the development programme, we committed to purchasing 48 F35s to replace the Harrier aircraft used on our aircraft carriers. Each of these machines will cost around £70million. That’s a total cost of around £3.36billion (£3,360,000,000 for those who like to see how many zeros there are in big numbers).

That’s a lot of money but maybe it would be worth it to ensure our armed forces were properly equipped. Except that the Ministry of Defence got itself in a bit of a muddle over which aircraft to order.

Originally, the F35B was selected as its short take off capability matched the Harrier’s principal feature. When the Tories came to power, however, they instituted a strategic defence review and part of this recommended changing the order to the F35C carrier variant on the grounds that it would be slightly cheaper. A sensible decision, you might think, except that civil servants aren’t aviation experts and they made one fundamental mistake.

You see, the USA uses nuclear reactors to power its aircraft carriers. These engines also provide the power for the catapults that launch carrier-borne aircraft in take off. This is necessary because even though aircraft carriers are enormous vessels, the flight deck isn’t long enough for a modern jet aircraft to reach take-off speed, so they are boosted into the air by a catapult. The F35C was designed to work with these catapults.

In the Royal Navy, though, we don’t use nuclear-powered engines, which means British catapults don’t generate the same boost. As a result, when actual military experts looked at the F35C, they realised that, on the new British carriers, these aircraft would shoot along the flight deck and promptly fall into the sea when they ran out of take-off space. That’s a bit of a waste of £70million each time it happens, not to mention the risk to the pilot’s life.

So, now the UK has been forced to go back to ordering the more expensive F35B which can take off from short flight decks. Well, it could if its engines didn’t keep bursting into flames unexpectedly.

Quite what all this fiasco is going to end up costing British taxpayers is anyone’s guess at the moment. Suffice to say that we could eventually end up with a batch of second-rate, highly expensive aircraft which aren’t nearly as good as the machines they are intended to replace. Goodness only knows what will happen if we ever need to use them in armed conflicts. It’s probably fair to say that the military chiefs in Moscow and Beijing aren’t losing much sleep over the F35. Still, as long as all we intend to do is bomb people in the Middle East who can’t shoot back, maybe they’ll work out just fine.