One of the innovations at this year's Paris Olympics should be an electric flying taxi service.

German Volocopter Commitment Its electric two-seater aircraft, VoloCity, will transport passengers around the city.

It never happened. Instead, the company conducted demonstration flights.

While missing the deadline was embarrassing, behind the scenes, a more serious problem was playing out — Volocopter was desperately trying to raise new investment to keep the company afloat.

Negotiating with government to borrow €100m (£83m; $106m) failed in april.

Hopes now rest on China's Geely, which is in talks to acquire an 85% stake in Volocopter in exchange for $95 million. According to Bloomberg. The deal could mean any future manufacturing will be moved to China.

Volocopter is one of dozens of companies around the world developing electric vertical takeoff and landing (EVTOL) aircraft.

Their machine has the flexibility of a helicopter but without the cost, noise and emissions.

However, some investors are pulling out, faced with the huge costs of getting such new aircraft approved by regulators and building manufacturing capacity.

Lilium is one of the most high-profile casualties.

The German company has developed a A radical interpretation of the EVTOL theme.

Lilium's aircraft uses 30 electric jets that can bank in unison, swinging between vertical lift and forward flight.

The concept has proven attractive and the company claims to have received orders and memorandums of understanding for 780 jets from around the world.

It enables the use of remotely controlled scale models to demonstrate the technology. Construction of the first full-size jet has begun, with testing expected to begin in early 2025.

At the Farnborough Air Show in July, Lilium's chief operating officer Sebastian Borel seemed confident.

"We are definitely burning money," he told the BBC, "but that is a good sign because it means we are producing aircraft. By the end of the year we will have produced three aircraft and we have raised €1.5 billion."

But then the money ran out.

Lilium has been trying to secure a loan worth €100 million from KfW. However, this required guarantees from national and state governments, which never materialized.

In early November, the company placed its main business operations into bankruptcy proceedings and its shares were delisted from the Nasdaq stock exchange.

Currently, work on the new aircraft continues, and the company is working with restructuring experts to sell the business or bring in new investment. However, bringing new electric jets into production appears to be more challenging than ever.

A British manufacturer that has attracted much attention in the eVTOL market is Vertical Aerospace. The Bristol-based company was founded in 2016 by businessman Stephen Fitzpatrick, who also founded OVO Energy.

Its striking VX4 design uses eight large propellers mounted on slender aircraft-style wings to generate lift. Mr Fitzpatrick made ambitious claims for the aircraft, saying it was "100 times safer" and quieter than a helicopter at 20 per cent the cost.

The company has made progress. It began pilot testing earlier this year after completing a remote control testing program. Initially, these were performed with the aircraft tethered to the ground. In early November, it performed its first free takeoff and landing.

But there have been serious setbacks. In August last year, a remote-controlled prototype crashed and was seriously damaged when a propeller blade fell off during testing at Cotswold Airport.

In May, one of its key partners, engineering giant Rolls-Royce Exit transaction Supplies electric motors for aircraft.

Ambition remains high. Vertical Aerospace said it will deliver 150 aircraft to customers by the end of the decade. By then, the annual output is expected to reach 200 units and cash balance will be achieved.

But the company has experienced financial challenges and recently agreed Reached a rescue agreement with its largest creditor, Mudrick Capital of the United States.

Under the agreement, Mudrick will invest up to $50 million in Verticial, while a $130 million loan provided by Mudrick will be converted into stock.

This will leave the US investment firm with a 70% stake in Vertical, with Mr Fitzpatrick's stake reduced from 70% to 20%.

Mr Fitzpatrick said in a statement accompanying the deal: "This comprehensive deal, coupled with the recent pilot activity...means Vertical is well positioned to be a winner in one of the most exciting technologies of the 21st century."

Bjorn Fehrm, who has a background in aerospace engineering and has flown fighter jets for the Swedish air force, said that amid the turmoil, a European project is quietly getting on track. He now works at aerospace consulting firm Leeham.

he said Airbus is working on EVTOL project It is possible to survive.

The four-seater aircraft, called CityAirbus NextGen, has eight propellers and has a range of 80 kilometers.

"This is a technical project for their engineers, who have the money and the expertise," Mr. Feim said.

Elsewhere in the world, other well-funded startups are experiencing good changes in getting aircraft into production. These include America's Joby and Archer.

Once the aircraft are produced, the next challenge will be to see if there is a profitable market for them.

The first route might be between the airport and the city center. But will they make money?

"The biggest issues in terms of operating costs are the pilot and the battery. The battery needs to be replaced a few times a year," Mr. Feim noted.

Given all the uncertainty and expense, you might be wondering why investors are putting money into new electric aircraft in the first place.

“No one wants to miss the next Tesla,” Mr. Feim said with a laugh.