Two US fighter jets were due to make their international debuts this week at the year's most important aerospace event, the Farnborough Airshow. At the moment, only one of them is here.

The F-35 Lightning II may be the world's most expensive, most advanced military jet programme, but it was a cheap and cheerful budget aircraft that managed the trans-Atlantic crossing to Farnborough.

The Scorpion costs about $20m (£12m) a throw, is built from off-the-shelf components, and went from drawing board to first flight in 23 months.

The F-35 Lightning, conceived in the early 1990s and costing about $157m, is still in the US while engineers figure out what caused a fire that has grounded the entire fleet.

OK, making comparisons is unfair; the Scorpion and F-35 are lightyears apart in specification and functionality. But it is still slightly ironic.

Image copyright Textron Image caption The Scorpion flies over the Isle of Wight during its first appearance outside the US

Whit Peters, part of the company behind the Scorpion, was involved in the F-35 when he was Secretary of the US Air Force in the 1990s.

A few years ago, he and some colleagues had an idea for a new, light tactical fighter for general security and reconnaissance, positioned between existing cheaper, but ageing aircraft, and full-on strike fighters.

"We were pretty sure that there was a gap in the market," Mr Peters says. "It was about building something with enough tactical capacity to satisfy customers, but that also had low running costs. We are in an era when defence departments are facing budget cuts."

No customers

His company, AirLand, pitched the concept to manufacturers, but it was Textron, the US giant behind Cessna corporate jets and Bell Helicopters, that grabbed the opportunity.

In 2012, Textron AirLand Enterprises was born. "It started with a team of about 10, a whiteboard and a clean sheet," Mr Peters says.

Media playback is unsupported on your device Media caption The Scorpion jet went from drawing board to first flight in 23 months - but has yet to find a buyer

When you take on a new challenge there are always sceptics Bill Anderson, President, Textron AirLand

What makes the aircraft so ambitious is that it was conceived and built without a launch customer. Indeed, there is still no customer, which is why the Farnborough debut in front of military delegations from all over the world is so important.

Normally, projects on this scale would secure government money and a design deal at an early stage. Not this one.

Bill Anderson, Textron AirLand's president, will not reveal how much the company has invested. But analysts estimate the cost would be at least $100m to get just one show-plane ready.

"Was it very risky? Yes. Was it a smart risk? Yes," says Mr Anderson. "But the marketplace is very interested. We produce commercial products all the time. That was the approach here."

A lot of the technology inside the Scorpion comes from Textron's top-of-the-range Cessna Citation corporate jet. Some companies approached to get involved jumped at the chance. Others shied away.

Image copyright AFP Image caption Not the real thing: Lockheed Martin's F-35 did not make the start of Farnborough, so visitors have had to make do with a mock-up

'Some got it, some didn't'

"When you take on a new challenge there are always sceptics," says Mr Anderson. "Some of the companies that turned us down did so because [the Scorpion] was not in their comfort zone."

The question is: will the customer want something off-the-shelf, or will they want something specific? Damien Lasou, Accenture

The Textron pitch to sub-contractors was to view the aircraft as a commercial project with military potential. "Some got it, some didn't. Those that didn't are starting to show interest now," he says.

The use of off-the-shelf components keeps the cost down, but does that mean the aircraft is low-tech?

"I would not use the phrase low-tech," Mr Anderson says. "I prefer to call it mature technology. There's nothing low-tech about a Martin Baker ejection seat or a weapons system."

The two-seat, twin-engine Scorpion, made of advanced composites used in civil aircraft, will carry infrared air-to-air missiles and wing-mounted gun pods.

Border control, reconnaissance, maintaining no-fly zones: these are the main functions. Indeed, that is the role of most fighter aircraft missions these days.

Mr Anderson says the Scorpion's big selling point is its low operating costs - $3,000 an hour.

Global market

The US is currently using its F-16 super-jet on low-end missions in Afghanistan. "There's no air-to-air threat there," says Mr Anderson.

Image copyright AFP Image caption The F-16 Fighting Falcon in use in Afghanistan

"They are spending $18,000 an hour running the F-16. You're burning the life of the aircraft on missions it was not designed for."

He puts the global market for Scorpions at about 2,000. Countries in Africa, South America, and the Middle East are likely targets for sales. But what Textron would really like is the stamp of approval from the Pentagon.

There have been talks with US defence officials, Mr Peters says, but he isn't giving anything away. "We are working with more than one very credible country, so the outlook is good. I think that the US Defense Department has recognised that there is a need for something like this."

The Pentagon, along with defence departments around the world, have made no secret that the days when defence contractors would be spoon-fed dollars to produce long-delayed and over-budget equipment are over.

Mr Peters says the Scorpion fits squarely into this new environment.

Image copyright AP

Farnborough Airshow: In pictures

Financial flyer?

Analysts and experts are watching closely.

Dennis Muilenburg, chief operating officer at Boeing, calls the Scorpion "an intriguing study".

He told the BBC: "Capability at a low cost: that is the consistent theme across the defence and civil sectors these days." Given this environment Textron's "underlying idea makes sense".

Damien Lasou, managing director of the global aerospace and defence division at consultancy Accenture, agrees Textron is showing a different approach to defence procurement.

"Most defence programmes are complicated and delayed. Textron is offering something that is standard and fit for purpose," he says.

"The question is: will the customer want something off-the-shelf, or will they want something specific?"

The fact that Textron is gambling its own money, rather than the taxpayers', must have concentrated minds on the Scorpion's market potential.

But until the aircraft wins some orders, no-one will know if this particular project is a financial flyer.