Luftwaffe Oxygen Masks
During World War I, artillery and machine guns were the primary devastating weapons on the battlefield. In contrast, World War II was significantly influenced by aviation, with aircraft playing crucial roles in both offensive and defensive strategies.
The design of new planes took advantage of high altitudes, where thinner air leads to lower fuel consumption due to reduced aerodynamic drag. To enhance effectiveness, WWII aircraft were engineered to fly at higher speeds and altitudes, requiring technological advancements to address the challenges of high-altitude flight. Developments like oxygen breathing systems were essential for all the major air forces during the interwar period, ensuring pilots could perform at their best under demanding conditions.
Covering More Distance and Flying Higher
The need for oxygen equipment arose from these rapid advancements in aircraft design in the years preceding WWII. Planes were engineered to cover greater distances and fly at higher altitudes to evade enemy defences and improve the efficiency of bombing runs and reconnaissance missions. Flying at higher altitudes provided several advantages:
1. Increased Speed: Higher altitudes have lower air density, reducing aerodynamic drag and allowing aircraft to achieve higher speeds;
2. Enhanced Safety: Flying above the range of anti-aircraft guns and enemy fighters reduced the risk of being shot down by ground Anti-Aircraft artillery;
3. Strategic Advantage: High-altitude flight offered better vantage points for reconnaissance and targeting, essential for strategic planning and execution.
The Challenge of High-Altitude Sickness
High-altitude flight presents a significant challenge known as altitude sickness or hypoxia. This condition occurs when atmospheric pressure diminishes substantially, resulting in a decrease in available oxygen. Consequently, the body experiences a state of oxygen deficiency, which may impair both physical and cognitive functions. Such impairments can severely affect the ability of aircrew members to operate the aircraft effectively and safely.
Altitude sickness can occur in aviation when flying above 8,000 feet (2,400 meters) in an unpressurized aircraft, without giving the body enough time to adjust. Hypoxia can easily occur because the human body lacks an effective warning system against the threat. Symptoms can range from mild, such as headaches and nausea, to more severe, including fatigue, lightheadedness, shortness of breath, and cognitive impairment which can be deadly in aerial combat.
Combating Altitude Sickness with Oxygen Apparatus
To effectively combat high-altitude sickness, aircraft were equipped with advanced oxygen systems that provided pilots with a continuous flow of oxygen, ensuring optimal physiological function. This method proved to be the most comfortable and widely adopted option across all belligerent nations during the conflict.
Germany pioneered the study and implementation of rebreathing apparatuses with pressure-demand systems before World War I, recognizing the shortcomings of continuous flow systems, particularly for long balloon flights. However, the continuous flow method was a reasonable balance of comfort and efficiency, especially with an onboard regulator to adjust the oxygen mixture according to altitude. There was never the need or push to adapt pressure-demand systems for long-range missions. Conversely, the United States Army Air Forces (USAAF) opted for pressure-demand breathing systems.
The design of oxygen masks was as good as the secure seal around the face, enhancing both comfort and efficacy in oxygen delivery across various altitudes and atmospheric conditions.
Freezing and Anti-Freezing Oxygen Masks of the Luftwaffe
Flying in low altitudes, such as low sorties and transport missions, didn’t require the use of complicated masks. Where necessary, simple mouthpieces connected to an oxygen bottle were used. However, during high-altitude flights, the phenomenon of freezing can critically affect breathing equipment and oxygen mask hoses due to the extreme temperatures encountered. As pilots and crew members exhale, their breath introduces moisture into the mask and hoses. At high altitudes, where temperatures can plummet to well below freezing, this moisture can rapidly condense and freeze. The continuous flow of oxygen exacerbates this issue and causes ice to form on the interior surfaces and inside the hose. This ice buildup can obstruct the flow of oxygen, leading to potentially dangerous situations where the supply of breathable air is compromised.
While the Luftwaffe experimented with electrically heated masks, this was never adopted. The way by which this problem was tackled was by having an exhaust valve.
Variants of Luftwaffe Oxygen Masks
The Luftwaffe developed various oxygen mask models throughout WWII, each with unique features tailored to different operational requirements. Some of the notable models include:
HM5 and HM15
The Hm5 and Hm15 masks were one of the earlier models used by the Luftwaffe, with only a size difference between them. It featured a simple design with a rubber mask that fits snugly over the nose and mouth, with ribs to the front. A chamois liner was attached that could be tucked inside the flying helmet to create a seal. The mask was connected to the oxygen supply via a flexible hose.
An expiratory valve beneath the face mask, at the top of the hose, was an earlier attempt at reducing the backflow of exhaled air into the hose. These masks were fixed with a 3-point attachment strap.
10-69 Fighter Pilot mask
This mask is based on the HM5/HM15 model (Jagdfliegeratemmaske). It is non-freeze proof and is attached using 2-point straps. However, it does not include cold protection leather face liner. It is designed for use exclusively with the net hood, hanging on the right side, and can be easily donned with one hand. Pilots have reported issues with freezing, requiring them to pinch the hose to break the ice inside, which restricts the flow of oxygen.
10-67 (HM51) family
This model was the basis for many of the mask designs used throughout the war. It has a completely separate inhalation and exhalation pathway, drastically improving the anti-freeze properties of the mask. A valve for each pathway was present inside the mask and was kept warm with the exhaled air.
Drägerwerke’s early models designated this mask as the HM51 and some masks had both markings (“HM51 & “10-67”). Later modifications gave rise to 2 variants that removed the double cavity wall with no loss to its anti-freeze properties, thus being a lighter mask. The 10-6701 was fixed with a 2-point strap, which was aimed at fighter pilots, whereas the 10-6702 was fixed with a 3-point harness. These codes were embossed onto the mask itself, along with the size.
10-86 Destroyer Mask
The 10-86 mask (Zerstöreratemmaske) was an attempt to make fighter and heavy-fighter pilots switch over to an anti-freeze type mask, based on the 10-67 model. The strap was replaced with a 2-point strap but was not light enough to be well adopted by the fighter pilots.
Closed system 10-6701
Building onto the 10-67 mask, this variant was aimed at high-altitude pilots using high-altitude pressure suits. The problem with condensation was exacerbated in this setup, and thus a 2nd hose was fitted, which carried the exhaled air outside of the suit.
The development of oxygen masks was a pivotal advancement that significantly improved the capabilities of pilots during the intense air battles of World War II. To this day, this technology continues to enable pilots to operate effectively at high altitudes, addressing the challenges of altitude sickness and severe cold. Although Germany began the war with technological advantages and continued to innovate, it ultimately failed to advance beyond the technologies it initially possessed. This stagnation may have been due to the defensive nature of Germany’s position in later years.
In summary, the progress in aircraft design leading up to World War II underscored the necessity for effective oxygen systems to enhance pilot safety and operational efficiency.
Bibliography:
(1941). Höhenflugregeln mit Anleitung zum Einsatz der Atem- geräte. D. (Luft) 1205. The Reich Ministry of Aviation.
Prodger, M. J. (1997). Luftwaffe Vs. RAF: Flying Clothing of the Air War, 1939-45. Schiffer Military History.
“Wir Müssen Sauerstoff! German Aviator Breathing Systems.” Author’s Den, www.authorsden.com/categories/article_top.asp?id=69092. Accessed 1 Nov. 2024.