There is a detail by which the age of a car can sometimes be determined almost instantly. It's not the headlights, not the grille, and not even the shape of the bumpers. It's the small swivel glass near the front door pillar. Anyone who drove a VAZ-2101, Moskvich-412, or GAZ-24 probably remembers the simple ritual: press the latch, turn the triangular flap, and catch a narrow stream of oncoming air.
Today, such a solution looks almost archaic. But once, the vent window was a quite serious element of car ventilation. And the most interesting thing is that it disappeared not because it turned out to be useless. On the contrary, it was simply replaced.
Small glass with big possibilities
The vent window was not just a small window. Its design allowed changing the direction of the airflow depending on the angle at which the driver turned the glass. If the flap was opened slightly, the airflow could pass along the surface of the glass and create an area of reduced pressure. This helped to draw air out of the cabin.
If the vent window was turned further, it began to work as a small air deflector: the oncoming flow was directed directly into the cabin. It turned out to be a fairly versatile device. With one movement of the hand, the nature of the ventilation could be changed - from exhaust to fresh air supply.
Of course, the car did not circulate air on its own when stationary. The vent window required the car to be moving or at least an external wind. But the driver could ventilate the cabin without lowering the main side window. And this gave several advantages at once: less noise, less dust, and a significantly lower probability of rain entering the cabin.
Why a large window sometimes makes more noise
A large lowered side window has another feature. At certain speeds, the airflow around the opening begins to create strong pressure pulsations. A low-frequency hum arises, which is especially well felt in the ears. That is why the familiar trick of "opening the window on the highway" is not always comfortable.
Often, it is enough to slightly open another window to change the nature of the air vortices and eliminate unpleasant resonance. A small vent window usually allowed fresh air without such a large-scale disruption of the cabin's aerodynamics. This capability was especially valuable for cars that did not yet have a developed ventilation system.
How the vent window became an automotive standard
In its modern form, the swivel car vent window became widespread in the USA in the 1930s. On November 28, 1932, Alfred J. Fisher filed a patent application for the ventilation design of a closed car body. The application was associated with Ternstedt Manufacturing Company - a division of General Motors that worked with Fisher bodies. The patent described, among other things, the use of a swivel side window to organize airflow.
Already for the 1933 model year cars, General Motors promoted a system called Fisher No-Draft Individually Controlled Ventilation - "individually controlled ventilation without drafts." The name quite accurately described the idea.
Each passenger could independently regulate the air intake without forcing the entire cabin to drive with a large window open. Later, such glasses were called ventipanes, and then the simpler vent window became common. Thus, the small swivel glass became part of the familiar car design.
Why smokers especially loved vent windows
The vent window had another unexpected advantage. It allowed creating a directed airflow that drew smoke out of the cabin. At the same time, it was not necessary to fully open the side window. For smoking drivers and passengers, this was especially convenient in rainy weather.
The main window could be left closed, and a slight turn of the flap provided air exchange. Rain entered significantly less. Today, such a function has practically lost its meaning, but a few decades ago it was a very real advantage.
Why vent windows began to be abandoned
The first to gradually abandon the familiar design were not due to the appearance of air conditioning as such. The reason was broader. Cars began to receive full-fledged ventilation systems capable of independently taking fresh air from outside, distributing it throughout the cabin, and exhausting stale air through special channels.
A very illustrative example appeared at General Motors in 1966. The Oldsmobile Toronado and Buick Riviera received solid front side windows without traditional vent windows. Instead, a flow-through ventilation system was used: outside air entered through the front of the body, passed through the cabin, and then exited through the rear vents.
For the Toronado, GM itself directly advertised this system as draft-free ventilation. Air passed through adjustable deflectors and circulated throughout the cabin with the windows closed. This was an important point. The car no longer needed to catch air with a small swivel glass. Now the flow was created by the car itself.
Air ducts made the vent window unnecessary
The new system had a fundamental advantage. The vent window depended on driving conditions. Its effectiveness changed with the speed of the car, the direction of the wind, and the angle of rotation of the glass. Air ducts worked differently.
The flow could be directed to the face, feet, or windshield. It could be heated, and in more advanced systems, cooled and dehumidified. That is, different functions that were previously partially performed by the vent window were gradually divided between specialized systems.
Air supply was handled by ventilation. Temperature - by the heater and air conditioner. Moisture removal from the glass - by the defroster system. And the tightness of the cabin - by the body structure itself. And the vent window simply had nothing to justify its existence.
But air conditioning was not the only reason
It is important not to simplify the story here to the formula "air conditioning appeared - vent windows disappeared." In 1968, air conditioning was indeed already very common equipment for the American market: according to the US Department of Commerce, factory air conditioning was installed on 45% of domestically produced cars, compared to 38% a year earlier and 29% in 1966.
But the abandonment of vent windows began as an independent direction. Manufacturers wanted to get a solid side glazing surface, reduce the number of mechanisms in the door, and improve tightness.
The vent window had an axle, a latch, separate seals, and a locking mechanism. Each additional element could potentially become a source of play, noise, or leakage. Old cars show this well: decades later, it is often the vent windows that start whistling at speed, fit poorly against the seal, or leak water.
A large window turned out to be simpler
The transition to a solid side window required redesigning the door and window regulator. But after that, the door became more integral. It was not necessary to separately attach the swivel flap, install its axle, and ensure the tightness of the additional connection.
At the same time, the protruding element that directly contacted the oncoming airflow disappeared. This was important both from the point of view of aerodynamics and from the point of view of acoustic comfort. That is why in advertising materials of that time, the absence of vent windows was already presented as an advantage: a solid side window provided a wider view and allowed the body to be visually cleaner.
Why Soviet cars also abandoned vent windows
The Soviet automotive industry is particularly indicative. The VAZ-2105 and GAZ-24-10 received doors without the usual front vent windows. At the same time, no one offered their owners a full-fledged air conditioner as a replacement.
And this precisely proves that air conditioning was not the only reason for the disappearance of the small glass. Cars switched to more advanced body ventilation regardless of the presence of air conditioning. The main side window became solid, the door became more airtight, and air entered through the channels provided by the design. Yes, such a system could not cool the cabin in summer as an air conditioner could. But for ordinary ventilation, it no longer required a separate swivel window.
Why the vent window was also a safety problem
The old vent window also had another drawback - the mechanics themselves. The small flap was held by a latch and had its own frame. For the car, this meant an additional weak point in the door structure. In addition, an opening vent window potentially simplified unauthorized access to the cabin.
Therefore, as locks, window regulators, and body structures improved, manufacturers had more and more reasons to abandon the separate opening flap. It was convenient, but its advantages gradually ceased to outweigh the disadvantages.
Why the triangular glass is still found
And here arises a funny paradox. The vent window disappeared, but the small triangle near the front pillar did not go anywhere. Only now it is usually fixed. The reason is no longer ventilation, but structural.
A large side window must move inside the door, and space there is limited. In addition, the shape of the door and the inclination of the front pillar do not always allow the lowering part of the glass to be a single large panel. Therefore, the glass is often divided into a main movable part and a small fixed element.
The triangle remains in its place, but now it does not ventilate anything. It simply helps designers place the glass inside the door and maintain the desired shape of the side glazing.