Picture any aircraft of your choice. What’s the first thing you think of? What's the last? Windows themselves don't seem to be an essential part of an aircraft but can you imagine a plane without them? The truth is that they have quite a rich history and a very significant role.

Fateful Windows of the Early Comet

The world’s first-ever commercial jetliner, the de Havilland DH 106 Comet, is mournfully remembered because of the stress concentration that led to a fatal mid-flight accident. When the Comet was introduced back in the 1950s, in-depth knowledge on aviation was scarce and it was overlooked that the smallest crack or hole in an aircraft could lead to a build-up of pressure. Frequent pressurizing and depressurizing of the cabins caused metal fatigue, a process which weakens the material and in this case ultimately led to catastrophic results. Regrettably, the Comet’s design incorporated perfectly square windows. The right angles in each corner allowed for an easy build-up of stress during the flight. Fractures that at first were invisible to the naked eye later had disastrous results.

What’s even more unfortunate is that it took three such incidents spanning just over a year between May 1953 and April 1954 before the Comet was finally grounded and the source of the problem was detected. Making for a tragic chapter in the history of aviation, these failures provided an unforgettable lesson. All windows on aircraft designed ever since were fitted with rounded edges without rivets. That significantly reduced the chance of stress concentration and vastly increased passengers safety.

The findings from the Comet model gave grounds for a more thorough understanding of the importance of plane windows. A gradual development began in this field and it's still ongoing. Striking a balance between aesthetics and performance is a tricky task and today we can see a great deal of variance from one aircraft to another.

Further Changes in Window Design

Although private jet designers have learned not to include right-angled frames, this doesn't mean that the square and rectangular design completely disappeared. Bombardier’s Global 7000 model, dubbed the “Rolls Royce of the skies”, is one such aircraft. The sixteen identical windows on each side of the plane offer ample natural lighting and are notably larger compared to the small rectangular windows often found on lower budget aircraft which may cause an unwanted, stuffy feel. The superior size is key here, and the linear structure is ideal for making the most out of each passenger’s space. Note that the edges never have right angles, but are gently curved and joint by straight lines.

Modern private jets and futuristic models are increasingly veering away from the traditional design towards something more adventurous. Gulfstream, one of the most respected airlines in operation today, is just as well recognized for its record-breaking speeds as it is for its iconic windows. The perfectly crafted oval shape has become a kind of a trademark for this growing brand. One of their finest models, the Gulfstream 650, boasts 28 inches wide windows (a 16% increase over previous models) that could freely be the same at home in a quaint country cottage.

It's not only the shape that differs across the types of jet windows of various manufacturers. Special effects can not only add an aesthetic edge but also save time and money. Honda’s HA-420 HondaJet, for instance, has self-tinting windows that adjust based on the external lighting, protecting passengers from the sun’s rays. This solution makes any type of blinds or shutters unnecessary which lowers maintenance costs and increases convenience.

Private jets of tomorrow offer a wide range of window shapes. Proposals are in place for the creation of the world’s first completely windowless private jet. The model designed by Spike Aerospace uses micro cameras on the exterior of the aircraft to display live images of the sky onto screen projectors giving the impression of elongated windows and enabling a live panoramic view of the exterior. The windows also double up as an interactive entertainment system with movies and internet browsing features.

The trend towards the modern is also evident in the Mercedes and Lufthansa Technik's concept. On this jet, windows are covered with black panels that have an adjustable level of transparency. They are flexible enough to be multi-functional, from a screen that serves for entertainment and information to fully transparent windows when the passengers wish to see the views of the skyline.

Airbus, too, have a penchant for innovation. It is demonstrated in their biennial competition 'Fly Your Ideas' where students from all around the world present their ideas for the future of aviation. Five groups get shortlisted and one receives a €30,000 prize alongside an invitation to explore the behind-the-scenes Airbus facility for a week. With their forward-thinking outlook, Airbus have also explored an idea that goes in the opposite direction of their windowless supersonic jet. They foresee a world where passengers can see in all directions, at all times. Such windows, as well as separate areas for working, relaxing and socializing, replace the traditional exterior and interior design.

We often fly without wondering too much why certain things are the way they are. It turns out, though, that some details may be more interesting than they seem to be and private jet windows are definitely the case. Therefore, consider taking a closer look at the windows next time you step aboard an aircraft.