Helicopters… with one blade
A 1922 cover of Popular Science magazine featuring a single-bladed helicopter…
“…and his power will be strengthened, though not by his own power, and he will make wonderful devastations and will succeed and act and destroy the mighty and the holy people…”
Daniel 8:24
Daniel 8:24
Innovations yesterday and today. It so happened that in the 70s and 80s, the Russian magazine "Modelist-Constructor" wrote a lot about models of... single-blade helicopters. They even competed in altitude and flight duration competitions. Their design was original, but back then I couldn't understand why anyone would need such flying... "projectiles." I also didn't know that this helicopter design had a very "ancient" origin. history" I'm not sure what the American magazine "Popular Science" wrote about them back in 1922. But today I'm reading about how this principle could be used to create a tiny flying machine that rotates in flight like a maple seed, and isn't much larger than one... And what could it be? It's this: another microdrone—an unmanned vehicle like a monocopter or "monowing," essentially a helicopter with just one blade! Although this idea, as it turns out, isn't new at all...
Let's put it this way: everyone has seen maple seeds. And everyone, of course, knows that instead of falling like stones to the ground, these seeds glide through the air, spinning around their axis like a helicopter rotor. True, it only has one blade. Strange, isn't it? But it turns out Mother Nature is different from humans in that she's very frugal, and where one blade would have sufficed, she decided not to install two! And, of course, watching the flight of a winged winged winged wing, people simply couldn't help but wonder: how could they not apply this natural principle of flight to their own aircraft? Although it has happened more than once that what's good for nature has turned out to be far less beneficial for humans.
What happened next was that on January 14, 1910, two French engineers, Alphonse Papin and Didier Rouilli, presented to the French Academy of Sciences a design for an unusual flying machine, reminiscent of a white maple blade in both its shape and propulsion. At the dawn of aircraft design, no one knew what was best or worst for flight, and interest in all sorts of original designs was exceptionally high. Besides, it was difficult to say in advance whether two blades or one would be better for a flying machine. Ultimately, Papin and Rouilli's design was approved, and the French army agreed to finance its implementation.
Nature gave the monocopter a very simple task: first, to slow the fall of a maple seed, and second, to allow it to fly as far as possible from its parent tree. For some reason, nature decided not to bother with the seeds of cherries, acorns, or chestnuts. They grew where they fell. But humans demanded much more from an aircraft built on this principle. And simplicity alone wasn't enough. It turned out that monocopters were more difficult to stabilize their flight path and keep the pilot's cabin stable. However, if the engine of such a "rotorcraft" failed, it simply couldn't crash. It simply glided to the ground in autorotation mode.
Papin and Rouilli named their craft Chrysalide ("Chrysalis"), clearly hinting that it could eventually develop into something truly remarkable. Furthermore, these craft were even classified as a separate class of gyropters, protected by two European and one American patent. The novelty of its design, however, was at first glance bewildering: "How could this even fly?" This strange "helicopter" (or perhaps a "helicopter wing"?) had only a single hollow blade, a whopping 17 meters long, and was a dead ringer for the maple-winged model.
The blade itself was located on one side of the pilot's cabin, and on the other, it was supposed to be balanced by a power unit—a nine-cylinder rotary engine, a "Rhone," producing 80 horsepower. It produced 1200 rpm and drove a fan, which forced air into the hollow blade. At the end of the blade, a nozzle ejected a jet of air at a speed of approximately 100 m/s, propelling the entire apparatus.
The "Doll" pilot was positioned at the center of gravity between the wing and the fan, allowing for the cockpit to be stabilized. The aircraft's flight direction was determined by the airflow, as some of the engine-driven air was diverted into a rotating air duct connected to the rudder, simultaneously pushing the aircraft in the desired direction.
The "Chrysalis" was built in 1913, but then World War I broke out, delaying field trials until March 31, 1915. They were conducted on a small lake in the Côte d'Or department—and fortunately, they were conducted on a lake. It turned out that the motor's power was woefully inadequate—the monocopter's rotor speed was insufficient for takeoff.
The test ended tragically: the pilot's cabin began to spin and shake so much that he only miraculously managed to jump out of it into the water, after which the "Doll"'s engine stalled, and it itself capsized and sank, even though it had a special hollow float at its base.
The apparatus was eventually recovered from the lakebed, and in 1917, its creators presented an improved design. However, they were denied the funding to build it, and were forced to search for it themselves for nearly twenty years, but still found nothing!
However, interest in single-blade helicopters would occasionally resurface. For example, in the September 1922 issue of the American magazine Popular Science, in addition to a lengthy article about the "Chrysalis" itself and its creators, the issue also discussed the practicality of such aircraft. "Do the 'maple seeds' promise a revolution in heavier-than-air aircraft?"It was decided that their disadvantages outweighed their advantages, and the magazine no longer wrote about such devices.
It would seem pointless to return to the winged-wing design right now. The design of this vehicle with a human inside is simply too cumbersome and complex. But what if we removed the human from it?!
Indeed: if a full-size monocopter controlled by a pilot still seems too inconvenient and unreliable to designers, then for a miniature one droneFor an observer, such a design could prove to be almost optimal. As a result, in 2006, almost a century after the first experiment, people again began thinking about creating fundamentally new devices based on maple seeds. Of course, the American agency DARPA had a hand in this!
It was this program that awarded Lockheed Martin a substantial grant for the development of a monocopter as part of the Nano Aircraft (NAV) program. According to the specifications, the new drone was to weigh no more than 20 grams and have a maximum wingspan of no more than 15 centimeters; furthermore, the minimum speed of the nanoreconnaissance vehicle had to be no less than 36 km/h. The computer-generated prototype was indeed the size of a maple-winged aircraft—a five-centimeter-long blade and a tiny jet engine spinning it at approximately 15,000 rpm. Sensors, cameras, and a communications device—in short, all of its equipment—had to somehow fit on board a device weighing only 10 grams. Work on this device continues today.
Ultimately, the company failed to create exactly this flying device, but it is still in development. Its blade length is 17 centimeters; an even larger model with a 40,6-centimeter wing is on display at exhibitions. It is this model that is being used to test its control system. In addition to its excessive length, this drone is also excessively heavy, weighing 227 grams, although it can lift, say, a video camera without issue. The jet engine had to be replaced with a microelectric motor and propeller mounted on the blade tip.
Meanwhile, three independent engineers from the University of Maryland—Ulrich, Pines, and Humbert—managed to build their own version of a monocopter drone, albeit without a definitive name. And not just one, but three drones, the last of which has a mere 7,5-centimeter blade. All of them operate on the same principle: winged blades and a pusher propeller. However, only the Maryland engineers managed to almost completely meet the customer's requirements.
As for observation drones built using this design, their advantage is that there's practically nothing to break. Apart from a tiny electric motor and propeller, they have no other moving parts. The problem of stable control of monocopters hasn't been fully solved yet, but who knows what could happen tomorrow?
But that's not all. If you watch a video of a single-blade helicopter launch, you'll notice it's performed from a ground-mounted strut. That is, the blade first spins, after which it takes off freely. But what if you strapped such a "strut" to the shoulders of... say, a special forces soldier, so that it could spin completely freely.
Two spaced micromotors with propellers can also be attached to his back. The spinning blade will lift him into the air, and the "craft" can be steered by increasing the speed of the right or left propeller! And there you have it, a finished "Karlson," who, while not living on the roof, is certainly capable of flight.
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