McLaren driver Fernando Alonso will miss the Monaco Grand Prix in May so he can race in the Indianapolis 500.

The double world champion has the full approval and support of McLaren and engine partner Honda, who are having a difficult season in Formula 1.

Alonso, 35, will race for the Honda-powered Andretti team on 28 May, and the car will be branded a McLaren.

McLaren are yet to decide who will replace him in Monaco that weekend, but Jenson Button is a possibility.

The 2009 world champion has retired from F1 but is contracted to McLaren as an ambassador. It is not known whether the Briton would want to come back to drive an uncompetitive car.Why does Alonso want to race at Indy?

Alonso said he had long held an ambition to win the so-called 'triple crown' of Monaco, the Indy 500 and Le Mans.

Only one man has won all three in his career - the late Graham Hill in the 1960s.

Alonso, who won the Monaco Grand Prix in 2006 and 2007, said: "It's a tough challenge, but I'm up for it.

"I don't know when I'm going to race at Le Mans, but one day I intend to. I'm only 35. I've got plenty of time for that.

The Spaniard added he would definitely race for McLaren for the rest of the season, dismissing speculation he could quit part way through the year because of the Honda F1 engine's poor performance.

"It's of course a regret that I won't be able to race at Monaco this year," he said. "But Monaco will be the only 2017 grand prix I'll be missing, and I'll be back in the cockpit for the Canadian Grand Prix in Montreal in early June.

"I've never raced an IndyCar car before, and neither have I ever driven on a super-speedway, but I'm confident I'll get to grips with it fast.

"I've watched a lot of IndyCar action on TV and online, and it's clear that great precision is required to race in close proximity with other cars on the far side of 220mph [354km/h]."

Alonso acknowledged he would be on "a steep learning curve".

But he added: "I'll be flying to Indianapolis from Barcelona immediately after the Spanish Grand Prix, practising our McLaren-Honda-Andretti car at Indy from 15 May onwards, hopefully clocking up a large number of miles every day, and I know how good the Andretti Autosport guys are.

"I'll be proud to race with them, and I intend to mine their knowledge and expertise for as much information as I possibly can."

McLaren have supported Alonso's wishes because they recognise the efforts he has been putting in - and the frustration he is feeling - after three uncompetitive seasons since joining the team in 2015.How will Alonso do?

McLaren executive director Zak Brown said: "Could Fernando win this year's Indy 500? Well, I wouldn't be so silly as to make any such rash prediction, but I expect him to be in the mix.

"Put it this way: the team he'll be racing for won the race last year, using the same Honda engine, and he's the best racing driver in the world. That's quite a compelling combination.

"OK, equally, he'll have his work cut out to acclimatise to running at super-speedway velocities, but ultimately it's quality that counts in all forms of motorsport, and Fernando is very definitely quality. He's ballsy and brave too."

Alonso joined McLaren-Honda with the intention of winning a third world title, but the package has been uncompetitive, with the vast majority of the blame lying with the Honda engine. His best results have been three fifth places.

He has won 32 grands prix - sixth in the all-time list - but has not stood on top of the podium since the 2013 Spanish Grand Prix in a Ferrari.

Alonso's contract runs out at the end of this season. McLaren want him to re-sign and there is a hope this will help persuade him to do so.38 years on - McLaren back in Indy

The unexpected development marks McLaren's return to the Indy 500 for the first time in 38 years. They won the race with their own car in 1974 and 1976.

IndyCars is a now a 'spec' formula, where all teams use the same car, though the different engine manufacturers are allowed to design their own aerodynamic bodykits.

The Indy 500 is the most prestigious race in the USA and is the blue riband event of the IndyCar Series.

The Andretti team, run by former Indycar and grand prix driver Michael Andretti, is one of the leading teams in the championship and won the event last year with American Alexander Rossi, who raced five times in F1 for the Manor team in 2015.

Andretti raced for McLaren in F1 in 1993 as Ayrton Senna's team-mate, completing 13 races with one podium finish before being replaced by Finn Mika Hakkinen and returning to race in the US.

While Formula 1 edges closer a decision on what type of cockpit head protection system will be introduced for 2018, Motorsport.com can reveal how the new 'Shield' idea being considered could look.

During Friday night's drivers' briefing at the Chinese Grand Prix, the FIA showed off a new canopy style solution that could be an alternative to the Halo or the Aeroscreen.

Here, for the first time, technical editor Giorgio Piola revealed his artists' impression of what the design could look like when fitted to a generic 2017 car.

Rather than the Shield being an attachment around the edge of the cockpit like the Halo and Aeroscreen, the solution is more integral to the nose section of the car – beginning much further forward that the two ideas already trialled.

The sloping see-through screen does not extend fully over the cockpit, even though it does end up higher than the crash helmet.

During a briefing made to drivers, they were told that while the design has proved effective in early testing for smaller pieces of debris, it is not as effective when it comes to deflecting larger items like wheels.

However, as there is resistance from teams, fans and drivers about the look of the Halo, it has been suggested that the Shield could deliver the best compromise between visuals and safety.

Some drivers believed it was more acceptable than the Halo, while others were not convinced.

Felipe Massa, who suffered a head injury when he was hit by a spring during qualifying for the 2009 Hungarian Grand Prix, believed that a final decision on which cockpit system to use should be made only on safety grounds.

"To be honest it looks really nice," said Massa, when asked by Motorsport.com for his opinion on the Shield. "It's beautiful compared to the Halo, but I don't think we need to go for how beautiful it is, but how better it is for the safety. That's the only answer we gave to them.

"If you can make it better, nicer and safer then it's done. Maybe for my accident it could have been okay this new system, but maybe for some other accidents maybe not. The wheels are much heavier now, so if you have a wheel flying and it hits it, it will not protect. So I push for the safety."

F1 teams and the FIA have agreed to introduce a form of cockpit protection for next season, but agreement has not yet been reached on which concept it should be.

A majority approval on the matter is required before the end of this month, otherwise the FIA will need unanimous backing from teams – something that may not be possible with several outfits not convinced about the need to cover cockpits.