Growing up, we had an American Linden tree in our yard which annually provided a wealth of “helicopter seeds” for my enjoyment. These nature provided toys were (and remain) fascinating to me. I have played with and dropped countless of them, from a wide variety of launch points, simply to admire their helicopter-like rotation and naturally controlled flight patterns.
It turns out that theses winged seeds, produced by several species of plants, such as Maple trees (and my beloved American Linden), are officially designated as Samaras. Although they have always been “helicopter seeds” in my mind, having a single blade, they are technically monocopters. The graceful descent that they utilize to more widely spread and disperse themselves is referred to scientifically as autorotational flight.
Researchers at the University of Maryland’s Clark Engineering School have recently designed some prototype vehicles based upon samaras. As you might expect, a single-wing rotating aircraft is not a novel a concept. Most previous work, though, has not attempted to simply mimic the basic autorotational properties of natural samaras. Instead, additional components have been integrated to facilitate controlled and stable flight (more along the lines of traditional helicopters). Earlier attempts at a much truer replication of natural winged seed aviation have not exhibited stable enough flight to address, say, navigation in a windy environment. This research breakthrough, then, represents a solution to a quite substantial and long-standing engineering challenge.
What, you may say, is the big deal? Scientists and engineers, at this point, have certainly developed and highly refined technologies necessary to make some very impressive aircraft. Well, the big deal is that these University of Maryland prototypes provide a number of important advantages that could prove very useful for the right applications. First, their flight is inherently stable and efficient. In addition, mechanically, the aircraft are relatively simple. This simplicity means less weight allocation to complex machinery, a higher lift-to-weight ratio, and, hence, significant potential payload capacity. These facts suggest possibilities of lower power, lower cost, and more reliable aircraft. Further, as they are built with flexible structures that deflect upon impact, such vehicles can be very damage tolerant. If the power source sustaining their flight fails, these aircraft can autorotate to a safe landing, just as we witness the samara doing in nature. These properties, then, could have significant survivability or safety consequences.
I am not an aeronautical engineer nor do I proclaim any other expertise in the field of aviation. I am, however, naturally curious and love to understand how things work. I find it very exciting when research such as this addresses concepts that are so tightly coupled to our common experiences with nature. Somehow, it just seems right that the mesmerizing and beautiful flight of the “helicopter seeds” I remember so nostalgically from my youth have now been successfully tapped for potential future aviation technology applications.
The inventor, graduate student Evan Ulrich, has now formed a company, X-Naves, to market his product. In an interview with Washington DC Fox News Reporter, John Henrehan, he indicated that two patent applications have been filed and toy versions of the monocopter could be in production within months. Ulrich will earn his doctorate in May. He thinks that the prototypes, which cost about $500 each to build now, could turn into a $100 toy with enough mass production. Baltimore’s WJZ-13 reporter, Suzanne Collins, reports use of his technology to develop highly maneuverable surveillance platforms looks promising. Because a camera attached to the single rotating wing would be facing all directions 10 times every second, it has advantages over a drone which photographs in a single direction. I wish Ulrich all the luck in the world – he’s certainly off to a bright and impressive start.
RoboSeed, Worlds first controllable robotic samara monocopter MAV, University of Maryland’s Ulrich flyer, YouTube
John Henrehan, Maple Seeds Inspire New Flying Machine, WTTG-Fox 5 (myfoxdc.com)
Suzanne Collins, Spinning Maple Seed May Help National Defense, WJZ-CBS 13 (wjz.com)
Evan R. Ulrich / Darryll J. Pines / Steven Gerardi, Autonomous Flight of a Samara MAV, University of Maryland
Evan R. Ulrich / Darryll J. Pines, Planform Geometric Variation, and its Effect on the Autorotation Efficiency of a Mechanical Samara, University of Maryland
Evan R. Ulrich / J. Sean Humbert / Darryll J. Pines, System Identification and Control of Mechanical Samara Micro-Air-Vehicles, University of Maryland
X-Naves Bio-Inspired Micro Scale Flight, X-Naves