The basic action of helicopter flight is that its rotors cut into the air to provide the craft with lift.
Remember when you were young, and you stuck your arm out of the car window, using the palm of your hand as a plane to get the rushing air to lift up your arm or push it down? Much the same thing goes on with a helicopter’s rotor blades.
When tilted up, the blades provide uplift; when tilted down, the blades offer downward motion.
Some of the considerations in the effectiveness of uplift are the speed at which the rotor blades turn, the angle at which they are tilted, and the air density.
The denser the air, the more lift it will provide. Ergo, the thinner the air, the less the lift.
At some point, the air will get so thin that the helicopter will no longer get sufficient lift to keep itself from falling out of the sky. The question then is, at what height does this happen?
How high do helicopters fly?
France’s Aérospatiale SA 315B Lama military helicopter achieved 40,820 feet in 1972, which remains the world record for the highest-ever altitude reached by helicopter. The Bell 47 is the highest-flying civilian helicopter at 18,500. Note that there are military variants of the 47, driven by more powerful engines than the 178 hp 47 variant, which conceivably fly higher.
The maximum height helicopters can reach: traversing and hovering
Before we get too deep into a discussion of how high helicopters can fly, it is important to understand the two types of flight that a helicopter can perform.
The first, just like an airplane, is zipping along horizontally; whether forwards or backward matters little to a helicopter, although most pilots might become somewhat excited to find themselves flying backward. The second type of flight a helicopter can perform is hovering.
When a helicopter is traversing horizontally, it gets an extra amount of lift due to its horizontal motion pushing more air against its rotor blades.
Thus, helicopters can fly higher when in horizontal motion than they can when hovering in one place.
Knowing this, we can expect two different maximum heights for helicopters; traversing maximum height and hovering at maximum height.
The maximum height helicopters can reach: what we mean by “maximum height”
There are times when we have no choice but to become pedantic, much though we might remonstrate and curse our fate.
We reach such an unwelcome juncture when we consider what we mean by “maximum height.”
Most folks instinctively mean, “The maximum height above the ground,” but what if the ground is already at an extreme elevation, say on a mountain top?
In some respects, the maximum height a helicopter can achieve has to do with how high off the ground it is.
Above ground at sea level, helicopters will achieve one maximum height, but above ground that is higher, depending on whether the craft is inside or outside the ground effect, the helicopter can achieve a higher maximum height.
The maximum height helicopters can reach: ground effect
My attempt at explaining to laypeople the “ground effect” is that it is the lift received by flying objects when such objects are close to the ground.
Some of the air passing underneath the body of the object acts as a “cushion,” and this cushion itself provides a degree of lift that is sometimes quite considerable.
Imagine a gradually sloping mountain that rises above a helicopter’s normal maximum height.
If the mountain isn’t strewn with such unfortunate objects for helicopter flight as trees or pylons, then a helicopter would be able to use the ground effect to crab up the mountain.
A helicopter with a maximum height of 10,000 feet could reach an elevation of 12,000 with the assistance of the ground effect.
The maximum height helicopters can reach: not all helicopters are the same
Just as different kinds of airplanes fly at different maximum speeds and achieve different maximum altitudes, so too, different types of helicopters achieve separate maximum heights, with military helicopters naturally going higher and faster than civilian ones.
It makes sense for military aircraft to outperform civilian ones because it is often a good idea to avoid fractious and resolute folks who are trying to shoot down your helicopter due to some particularly irksome difference of opinion.
The fact that different helicopters reach different maximum heights means we have yet another pedantic choice to make.
Are we looking for the maximum height that any helicopter has ever achieved, or do we care about the maximum heights that popular helicopters reach?
For that matter, if we were to take a broad swathe of helicopters into account, couldn’t we work out an average maximum height that would pretty much define a height for most helicopters?
Well, as the author of this piece, I have taken the executive decision to provide the maximum heights of military and civilian helicopters.
Those who have a passion for quibbling will probably point out that many military helicopters have civilian variants and vice versa. That’s okay.
The highest-flying military helicopter (the Aérospatiale SA 315B Lama) doesn’t do civilian stuff, and the variant of the highest-flying civilian helicopter (the Bell 47) is the civilian variant.
Afterword: How high do helicopters fly?
The maximum height of helicopters in hover mode depends on whether the craft is in ground effect (IGE), or not (OGE).
Helicopters fly even higher than they can hover, so a helicopter’s absolute maximum height will always be higher than its maximum hovering height.
Each helicopter’s actual type and make is a huge determinant in its maximum achievable height, since different helicopters reach different maximum heights.
Military helicopters tend to outperform civilian ones in terms of top speed and altitude
Frequently asked questions on “How high do helicopters fly”
Is it true that helicopters can often fly higher than their rated maximum height?
It is a fact that most helicopters can fly far higher than their rated maximum height. For example, FAA rules govern how high a helicopter can fly if its cabin is not properly pressurized. The limit here is 14,500 feet, which many helicopters, such as the Westland AW109, can physically surpass, but doing so could land the pilot in hot water with the FAA.
Does the ground effect have any practical use in increasing a helicopter’s maximum height?
Surprisingly, the answer is “Yes.” Without the use of the ground effect, mountain rescue helicopters would be forced to fly to lower altitudes. For example, the Augusta A109 hovers at around 10,400 feet, give or take. However, with the ground effect in operation, that maximum increases significantly to about 13,800, an incredible additional 2,500 feet of height gained.
Has anyone ever landed a helicopter on top of Mount Everest?
At the height of “only” 29,030 feet, Mount Everest is way below the 40,820 feet achieved by the Aérospatiale SA 315B Lama, so one would expect that pilots routinely land their helicopters atop Mount Everest. However, surprisingly, only one pilot has ever achieved this milestone. Didier DelSalle landed his Eurocopter AS350 Squirrel at the summit of Everest in 2005. To prove that it was a fluke, DelSalle returned to the summit and landed a second time the day following his earlier triumph.
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