Image copyright Bird Aviation Museum Image caption Dr Forrest Bird, who died in August, set up a museum in Idaho containing his collection of aircraft, helicopters and inventions

A love of flying and a passion for fixing things led Forrest Bird to save millions of lives with his invention of the first mass-produced ventilator - a machine which still helps people to breathe today.

In the 1960s, Dr Bird became used to doctors questioning the "little green machine" he'd brought to show them.

"A machine which breathes for you? That's not going to happen," they regularly told him.

Until then, respiratory problems had been treated using a heavy and restrictive piece of equipment known as an iron lung. But Bird knew he had come up with something better.

Inspired by his father, who was a World War One pilot, he developed a passion for aeroplanes at a young age.

He performed his first solo flight at 14 and, at the onset of WW2, he enlisted with the US Air Corps and was given the job of delivering aircraft and helicopters to wherever they were needed.

This love of flying machines was combined with an inventor's brain and a curiosity about the workings of the human body.

He had watched how air moved over a plane's wings, realising there was a similarity with airflow in the lungs.

He wrote: "In the human lung, there are millions of air foils, just like aeroplane wings, which facilitate normal breathing."

Image copyright Bird Aviation Museum Image caption Dr Bird's love of aviation inspired him to develop machines to help people breathe

During the war, Bird realised that Allied planes were at a disadvantage because their pilots couldn't fly at higher altitudes than the German planes for fear of passing out.

When he discovered a machine in a crashed German bomber for controlling the flow of oxygen to the pilot, he studied it and produced his own, improved version of the oxygen regulator.

His device enabled pilots to breathe at heights of up to 40,000ft - higher than they had gone before.

This device became the prototype of the Bird Respirator in 1950, which was pretty basic - made from three baking tins and a doorknob - but it worked as a means of blowing air plus oxygen into a person's lungs and preventing them from collapsing.

He was now studying medicine and after years of working in different areas, he returned to his invention and improved it once more for use in acute or chronic cardiopulmonary care.

Image copyright Bird Aviation Museum Image caption The Bird respirator Mark 7 dates from the 1950s and was once a standard piece of equipment in hospitals

Image copyright Bird aviation museum Image caption The Babybird, invented in 1970, was a ventilator which helped reduce the deaths of premature babies with breathing problems

The Bird Mark 7 medical ventilator was born - a portable, low-cost machine which moved air into and out of the lungs of patients with serious breathing difficulties, without the need for an electrical power source.

Despite the doubters, he knew it was reliable because he had flown around the world testing it on the most seriously ill patients he could find. Often, they were the patients that doctors had given up on, who were expected to die of cardiopulmonary failure.

His green machine became the first mass-produced ventilator in the world and soon every hospital had one.

Bird then turned his attention to premature babies, who were particularly vulnerable to breathing problems, creating the Babybird ventilator - a miniature version of his original design - to be used on small children and infants.

Introduced in 1970, the Babybird is credited with reducing infant mortality in premature babies due to breathing problems from 70% to less than 10%.

At the same time, Bird's first wife Mary had been diagnosed with advanced bronchitis and emphysema, serious lung diseases. This spurred him on to develop a device which cleared the mucus and fluid from the respiratory tract by pumping air into patients' lungs.

Although she was helped by the ventilator, Mary's lungs were too seriously damaged and she died in 1986.

Bird's inventions earned him a place in America's National Inventors Hall of Fame in 1995 and a medal for technology and innovation from President Obama in 2009.

Image copyright Bird Aviation Museum Image caption Forrest Bird with his wife Pamela

Dr Forrest Bird died in August at the age of 96. He was still flying in his 90s and was the oldest helicopter pilot in the world - and he never stopped inventing.

Several patents were still pending at the time of his death.

His collection of 21 aeroplanes, vintage cars and inventions (medical and otherwise), housed in the Bird Aviation Museum and Invention Centre in Idaho, are a testament to his insatiable appetite for fixing things.

His wife, Pamela Riddle Bird, was interviewed for this article but was sadly killed in a plane crash shortly after the interview was conducted.

A tribute posted on the Bird Aviation Museum and Invention Centre's Facebook page said she died in the crash in Hope, Idaho, on Thursday, along with her friends Tookie and Don Hensley.

"The three of them had a great love of aviation and adventure... They are gone but will never be forgotten," it said.

In the interview, Dr Pamela Bird said her husband had been "high energy, low maintenance" and a fantastic companion.

"I could talk to him about any subject. It was like being married to the internet. Any question and he knew the answer," she said.

According to his stepdaughter, Rachel Schwam, who now runs the museum which bears his name, he was regularly thanked by thousands of complete strangers for saving the lives of their premature babies.

Yet he was a very humble man, who was always creating something.

"He saw a need and wanted to figure out a way to fix it," she says.

What he was most proud of was the Babybird, she says, because he knew the impact it made on so many families, including his own.

Born a month early, Rachel herself had been saved by the little green Babybird ventilator.

What is a ventilator?