The BLB Oxygen Mask and Aviation

By the end of World War I it became clear to the U.S. Army that military aircraft, especially fighter aircraft, were going to have to fly higher than they did during World War I.

German zeppelins were flying across the English Channel at 20,000 feet while the German Crews suffered frostbite and hypoxia despite the fact they had primitive oxygen devices available.

The U.S. War Department, by 1918, had created the Air Service Engineeering Division along with it's flight test division and located it at McCook Field in Dayton, Ohio. This is where the first experiments in high altitude flight occurred.

Captain Rudolph "Shorty" Schroeder

Captain Schroeder was a wiry six-foot tall pilot with the soul of an explorer.

Capt. Schroeder stands by a Bristol fighter like the one he set a world altitude record in 1918.

By 1914 Captain Schroeder had made a name for himself in air racing, and in 1919 was chosen by his commanding officer to compete in the New York to Toronto air race.

McCook's engineers resurrected a Vought VE-7, fixed it up, and Shroeder flew it to victory in the race.

Photograph of a VE-7 Bluebird aircraft in 1919.

In 1918 Captain Schroeder was flying a new biplane from the US Army Air Service, a LePere C-11, which was dedicated to high altitude research.

The aircraft was powered by a normally aspirated 12 cylinder engine in a V configuration. This aircraft was America's first dedicated research aircraft.

Captain Schroeder, USAAC, flying a Packard Lepère L U.S.A. C.II over McCook Field, Ohio, 24 September 1919.

Captain Schroeder achieved altitudes of 24,000 feet and 27,000 feet on his early attempts; however, once he passed 23,000 feet he felt sleepy, tired, cross and hungry - the symptoms of hypoxia. He relieved the symptoms with oxygen from an oxygen bottle and mask.

The mask, however, was so snug that it numbed his face, and as the flight progressed the hose and oxygen mask were covered by a 1/4 inch of frost!

On one of the flights he experienced hypoxia as he passed 25,000 feet, but he continued to climb and by 27,000 feet he couldn't see his aneroid altimeter because of the frost on his goggles.

It was minus 60 degrees Celsius, the air was so cold his eyes watered, but he could see that he almost reached 29,000 feet.

The airplane ran out of fuel, began to spiral down towards the ground below, and finally broke out of the clouds over Canton, Ohio where he made a forced landing in a field.

His hands and face were entirely numb while four of his fingers were frozen and required immediate medical attention.

Finally, on February 27, 1920, the newly promoted Major Schroeder set a new world record of 33,113 feet. The flight took an hour and 47 minutes, logged an airspeed of 119 mph, and almost cost the Major his life.

Hypoxia, Aviation and Oxygen

In order to understand hypoxia we need to understand several things. Our lungs are used to taking in oxygen at the surface of the earth, and at the surface of the earth the pressure of the atmoshpere is nominaly 14.7 pounds per square inch.

As we move higher in the earths atmosphere the air becomes thinner, which in turn reduces the amount of pressure in the atmosphere. For example, at 10,000 feet the atmospheric pressure is 10.2 psi, at 20,000 feet it is 6.75 psi, and at 40,000 is 2.72 psi.

So whether you are climbing up a hill, climbing a mountain, or flying an airplane the outside atmospheric pressure goes down.

Why does this matter? Hypoxia, by definition, is the lack of sufficient oxygen in the blood, tissues, and/or cells to maintain normal physiological function.

Hypoxia is easy to succomb to because our bodies do not have an effective warning system against the threat.

As we saw earlier in this post symptoms of hypoxia are increased breathing rate, headache, lightheadedness, dizziness, tingling or warm sensations, sweating, poor coordination, impaired judgment, tunnel vision, and euphoria.

The History of Hypoxia

In 1620 Dutch inventor Cornelius Drebbel invented the first hypobaric chamber for divers, and by 1860 the first hypobaric chamber in North America was made in Oshawa, Canada.

In 1875, Gaston Tissandier and two others ascended to 21,000 feet in a ballon. They carried three bags of oxygen, but they succombed to unconscousness, two of whom died.

In 1878 physiologist Paul Bert discovered that the oxygen partial pressure in the inspired air is responsible for hypoxia, and not the barometric air pressure as previously suspected.

The BLB Oxygen Mask

In 1938 three phsycians by the names of Walter M. Boothby, W. Randolph Lovelace II and Arthur H. Bulbulian designed the first oxygen mask to overcome low inspired oxygen partial pressures in aviation.

A Side-View Drawing of BLB Oxygen Mask Patent Application in 1938.

Over a period of nine years the mask continued to make improvements, and during World War II the mask was essential for military aircraft like the B-17 flying at 40,000 feet.

A table of Patents for the BLB Oxygen Mask

On March 10, 1939, the mask was used on a flight by Northwest Airlines from Minneapols, MN to Boston, MA, at an altitude of 23,000 feet, and lasting four and a half hours. On board were Boothby, Lovelace, Bulbulian and others who wore the BLB mask supplied with oxygen from a large tank.

A photograph of the test flight published in Polular Aviation June 1939.

Below is a photograph of the Instructions For Use of the BLB mask:

Instructions for how to use the BLB Oxygen Mask.

There are actually four types of hypoxia: hypoxic hypoxia, hypemic hypoxia, stagnant hypoxia, and histotoxic hypoxia. No matter which type you experience as a pilot, the symptoms and effect on flying skills are the same.

If you follow aviation at all you no doubt have learned of incidents where the crew in an aircraft at high altitude suddenly stop communicating. When chase fighters are launched to intercept the aircraft they can find no motion in the cockpit, and the aircraft continues flying until it runs out of fuel.

This is one of the reasons many in the aviation industry believe that pilots who intend to fly above 10,000 feet should be required to get trainin in high-altitude physiology and spend time in a high-altitude chamber.

I actually used the modern version of this mask when I flew my Piper Navajo across the Rocky Mountains a few times.

I hope you enjoyed this trip through some of the history of aviation. If you enjoyed this trip, and are new to this newsletter, sign up to receive your own weekly newsletter here: Subscribe here!