Why did the De Havilland Comet, the first operational Jet airliner, have unswept tail surfaces?

lowlevel

Because the tail surfaces had the required fineness ratios even though they were unswept. High subsonic and transonic and even supersonic aircraft do not require swept surfaces. They just have to be made thin enough that they don’t form strong shockwaves and cause transonic drag. A wing is usually required to hold fuel, landing gear, etc so to make a straight wing that’s thin enough is very difficult. It also typically requires several spars to meet required strength. A swept wing can be made thicker since the effective chord is parallel to the airflow. Tail surfaces are made thinner much easier since they are lightly loaded and have nothing inside them.

Anonymous

A moot point, as many blew their windows out.

Vincent G

Because they don't need them. In fact, most aircraft really do not need tail planes to be swept at all. In aircraft flying at high subsonic (or transonic) speeds, the need to produce lift requires the airspeed on the upper surface to increase, locally reaching the speed of sound. Keeping that speed below Mach 1 is important as drag increases significantly when air has to go through a shock wave (transition between a speed slightly above Mach 1 and slightly below). A wing sweep allows to manage that speed variation because the angle makes the wing appear to be comparatively wider for the air in the airflow direction, while remaining comparatively thick. The tail surface, on the other hand, do not have to produce significant lift since their contribution is only a matter of keeping the plane in balance and control. With the overspeed limited to a level well below that of the wing, the need for sweepback is essentially gone. Most aircraft have seepback tail planes only for cosmetic reasons.

USAFisnumber1

The engines were center mounted in the wings. The turbulence from them screwed up the tail controls. By angling the tail surfaces up a bit they got them out of the way of the engine wash. With other planes the engines are mounted below the wing on pylons so the tail surfaces can be straight out.

FlagMichael

Swept wings were a subject of a lot of investigation in the mid-1940s, when the Comet was designed. See the source for details. The same applied to the tail. We really didn't know much about peri-sonic air flow.

Robert S

So it would fly.