I’ve been checking some aviation simulators. The gateway drug was the free(ish) Falcon BMS with its strong focus on F-16. Then Huey helicopter model in DCS got me intrigued. So I’ve been trying it for a couple of days. In helicopters that are not overly automated, stability is not granted at all and requires special attention from the pilot. That makes them interesting.

Flying over the Cold War Berlin made some Der Himmel über Berlin associations. Considering the technicalities of the flight I saw Apocalypse Now, too. Mixing technology and the arts, I wanted to bring odd can of soup painting into the post but maybe I was just hungry.

Vortex Ring State

VRS happens when you are trapped in a column of disrupted air created by your own rotor blades, and this (unfortunately) often occurs at the most critical part of flight: on LANDING.

A fully developed vortex ring state is characterized by an unstable condition in which the helicopter experiences uncommanded pitch and roll oscillations, has little or no collective authority, and achieves a descent rate that may approach 6,000 feet per minute (fpm) if allowed to develop.

The idea is that “new air” input allows the system to move/climb, but inside the vortex ring state it’s only the “old air” circulation. The point is that if the condition is allowed to develop then powering out of it would not work in aircraft of interest, because it only rotates the pattern of air faster and gives it more energy for sinking down, but does not introduce new input, so fall continues.

So there seem to be two ways out - by gaining forward momentum while still losing height/energy so it may not be applicable, or by more economical side maneuver using tail rotor that is unaffected/orthogonal to the vortex ring.

Normally one corrects it early because it’s noticable in different ways including low-g feel of accelerating down.

Autorotation

Unrelated to VRS but also significant is autorotation. This one can be used when the engine loses power and the rotor is kept rotating only by the airflow coming from a controlled descent/fall, to reduce the rate of falling. It requires good control over the parameters by the pilot and even using stopping power of flares at certain points.

In case you are crazy

Hardware is quite a cost sink when it comes to simulators. Otherwise, the helicopter is free to play for two weeks; the Germany map is not free to play at the time; Chuck’s Guides: Huey Guide is the go-to guide.

Credits: https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook, images 2017 valair.ch / aerialstage.com