the lengths people will go to in order to set a record... like changing spark plugs mid air

Frequent repairs were made on the plane while it was in flight. “Spark plugs were changed, a magneto overhauled, and even a lost bolt in the engine mount replaced, as well as regular oiling of the rocker arms. For this purpose a light metal cat walk was rigged from the cabin doors to the engine on either side, and Kenneth Hunter, the younger of the four brothers, made regular trips to the motor. He also clambered out of the refueling door in the top of the fuselage and slid back to the tail to clear away string paper and other debris, blown back during refueling contacts, and threatening to jam the control cables.”

Daredevils, barnstormers, and record-breakers, the Hunter Brothers of Sparta were pioneers in the field of aviation, dazzling spectators around the country with feats of sport and endurance in the sky.

The four brothers – Albert, John, Kenneth, and Walter – were the sons of Alexander and Ida Blair Hunter.

The brothers first gained notoriety in Sparta for their motorcycle stunt riding. Each spring, they would ride their motorbikes to St. Louis to trade them in for newer models.
On a whim, they decided to sell their motorcycles and buy the airplane. One brother, John, was assigned to stay behind in St. Louis and learn to fly the new plane, while the other three headed back to Sparta. He managed, after only 90 minutes of instruction, to pilot the plane back across the river

Soon, they had graduated from motorcycle stunts to trick flying. By the summer of 1924, they had acquired two more planes, and they were performing air stunts with Gurney at county fairs all over Illinois and Indiana. They dubbed their act the “Hunter Flying Circus.”

All four of the Hunter Brothers began aviation careers that included airshow performances, passenger service, and even airmail delivery. They became good friends with the man who would become the most famous aviator of his age: Charles Lindbergh.

By the late 1920s, the brothers’ airmail careers had them flying all over the Midwest, in the autumn of 1929, John and Kenneth Hunter made their first serious attempt to break the endurance flight record.

The brothers managed to stay in the air for 264 hours – 11 days – but they were forced to land before breaking the record, as a heavy fog had prevented their refueling plane from making contact.

All four brothers banded together the following year to make another run at the endurance flight record.
With John and Kenneth piloting the “City of Chicago,” and Walter and Albert flying the supply plane, the brothers flew over Sky Harbor Airport in Northbrook, Illinois, for 553 hours, 41 minutes, and 30 seconds, breaking the world record for endurance flight.

The “City of Chicago” finally landed at Sky Harbor on July 4, 1930, in front of a cheering crowd of 75,000.

In 1930, the four hired a press manager to help with the business and publicity aspects of the flight.  Will Rogers, the famous actor, writer, and aviation enthusiast, brought national attention when he flew in the supply plane during the attempt. He also hosted a banquet for the brothers in Chicago after the flight had ended.

Although their endurance flight record did not stand the test of time – it was broken in July 1935 by the Key Brothers of Meridian, Mississippi – the airport stands today as a monument to the important early aviation careers of the four brothers from Sparta.

The brothers’ passion for aviation led them to campaign for a permanent airfield to be built in Sparta. Without a dedicated landing field, they had been landing planes in empty pastures and fields. In May 1931, Hunter Field was officially opened north of Sparta. It remains the primary airfield in Randolph County today.

Walter Hunter continued flying, embarking on a long career as a pilot for American Airlines, becoming the airline’s senior jet captain before his retirement in 1966

https://randolphsociety.org/the-hunter-brothers/
https://daysgoneby.me/have-you-ever-heard-of-the-famous-aviators-the-hunter-brothers-from-illinois/