Sensenich, arguably the best-known manufacturer of wooden propellers, has been around for almost 100 years. It has a fascinating history, but what does the future hold for this remarkable company?
To gain greater insight, we spoke to Sensenich’s Steve Boser, vice president, engineering. Boser has been with Sensenich from 1993, when he joined the company as a junior design engineer. At the time, rather ironically, he was a glider pilot, although he has since moved on to flying propeller-driven aircraft.
The company was incorporated in 1932, but it began in rural Pennsylvania during the 1920s, when two brothers, Harry and Martin Sensenich, who loved to tinker, procured an old World War I-era engine. According to Boser, they “proceeded to fit it to a wagon, a sled, and different contraptions they could find on their dairy farm. Their wagon worked well. It was called a ‘Wind Wagon’, but eventually they were banned from taking it into town.” The brothers then fitted the engine to a snow sled. One winter, while operating on ice, the brothers’ unique air-driven vehicle crashed, breaking its expensive propeller. At the time, it was rare for someone to be knowledgeable about propellers. Boser explained, “They were pretty good with their hands, so they thought, ‘hey, let’s make our own propeller!’”
The brothers successfully crafted a propeller for their sled. Soon, local pilots took notice and reasoned, “If you can make a propeller for that thing, you can make propellers for our aircraft.” Boser continued, “They started carving aircraft propellers, and by the beginning of World War II, they were the largest manufacturer of wooden propellers in the world. We still have that title today.” During the Second World War, which lasted from 1939 to 1945, Sensenich had more than 400 employees crafting propellers 24 hours a day to support the war effort. These propellers were primarily for liaison aircraft and trainers, as well as experimental projects.
Soon after the war, Sensenich produced a tremendous number of propellers for private light aircraft. Later, in the late 1940s, the company diversified and began making metal fixed-pitch propellers, while also servicing and maintaining other companies’ propellers, in addition to manufacturing a variety of wooden products. During the 1950s, Sensenich also began designing and manufacturing target drone propellers, as well as airboat propellers. Airboats, which have grown in popularity in places such as Florida, are essentially flat-bottom boats pushed by propellers, which are similar in appearance to those found on aircraft. Today, Sensenich produces more airboat propellers than aircraft propellers.
By the late 1980s, the company had been operating separate divisions for propellers and for wood products. The Sensenich family was forced to sell one of its divisions, either propeller manufacturing or its wood product division, which made table tops and bench seats. A Philadelphian family purchased the propeller company and continues to own Sensenich Propellers to this day. In 1994, the company’s three divisions, namely wood propellers, metal propellers and its service division, were separated. The service division had a management buyout, while the wooden propeller division was moved to Florida, the primary market for airboat propellers. The metal propeller division remained in Pennsylvania. In the late 1990s, Sensenich turned its focus to composite propellers for aircraft and airboats, while also ramping up production of unmanned aircraft propellers.
Today, Sensenich has about twenty employees in Pennsylvania, where metal propellers are produced, and about fifty employees in Florida, where the company focusses on wooden and composite propellers.
In terms of aircraft. Sensenich propellers are primarily used by experimental aircraft, trainers and vintage aircraft. Most of the company’s wooden propellers are used by vintage or antique aircraft. Sensenich produces about 4,000 wooden propellers per year, although, due to demand, its carbon fibre propeller production numbers increase significantly every year. How has covid-19 restrictions affected Sensenich? According to Boser, “Last year was probably the busiest year of the past ten years. This year is off to an even better start.” He continued, “When people are at home, they have more time on their hands. They need propellers because they are either working on kit airplanes or they are out flying.”
Sensenich currently produces about 150 to 200 composite propellers per month. Is that where the future lies? “Most of the development is on the carbon fibre product line,” explained Boser. “Wood is economical for developing a propeller in a short timeframe. It requires minimal tooling to make a wooden propeller. The engineering requirements for wooden propellers are much less than metal or carbon props, so new wood props can be made in a couple weeks. A metal prop requires vibration testing for good service life. That is an incredibly involved project and it’s a fairly mature product line. Carbon fibre offers advantages in strength, weight and configuration, with engineering demands between wood propellers and metal propellers.”
What about unmanned aircraft? “We do see a lot of potential with UAVs (Unmanned Aerial Vehicles) in the future, but our sales are fairly steady.” Sensenich develops propellers specifically for mid-size, or tactical-size, UAVs. “We are doing product development across the board with all our products,” said Boser. “We have just received an stc (Supplemental Type Certificate) from the FAA for installation of one of our composite two-bladed propellers on STOL (Short Take-Off and Landing) aircraft. We plan on doing a further STC for lower horsepower SuperCubs. Then we will be looking very closely at the market before we decide on follow-on STCs. The light sport market is very active too. We recently released a number of new prop designs for the light sport and experimental market.” Intriguingly, Boser also mentioned, “We have some pretty exciting things coming up. I don’t want to give out too much about that, but it’s a very new area for us.”
“The recently released STOL propeller for bush planes is very exciting for us,” Boser added. “We are preparing to apply for a Canadian STC.”
Of course, the development of the eVTOL (Electric Vertical Take-Off and Landing) industry is quite exciting. “We have been remarkably busy prototyping for that market, and we have become one of the top fabricators for prototypes and test articles for the eVTOL market.” He added that, “we deal with mature but innovative programmes. There is a whole range of projects out there, so we focus on the ones where we can have the most impact and provide the most value.
Launched by SpaceX and Tesla veterans, Reliable Robotics has made great strides in the development of unmanned aircraft technology. Recently, the company revealed some of its milestones in pioneering unmanned aviation.
Based in California, Reliable Robotics was founded in 2017 by Robert Rose and Juerg Frefel. Robert Rose, who previously led development teams at Tesla, SpaceX and Google’s X, has considerable experience in engineering systems for robotics, self-driving vehicles and the aerospace industry. Co-founder Juerg Frefel, developed systems for the Falcon 9 rocket and Dragon spacecraft at SpaceX.
With a staff complement of about thirty people, the Reliable Robotics team began modifying a Cessna 172 in December 2017. Before the end of the next year, the 172 completed its first fully automated gate-to-gate remotely operated flight. Then, in September 2019, the aircraft completed another automated flight, this time without any test pilots onboard. It was the first time a privately funded company operated a passenger aircraft of this type with no pilot on board over a populated region. “We spent the first portion of our flight test programme focused on the C172. We thoroughly tested every aspect of our system in simulation and conducted rigorous safety checks before operating the aircraft without a pilot on board and are now proud to share what we’ve been working on,” said Robert Rose in a company press release.
According to the release, the Cessna 172 was equipped with a “proprietary autonomous platform that can be applied to any fixed-wing aircraft. The platform includes avionics, software, mechanisms, a communications system, remote control interfaces, along with a backup system that has the capability to take over if needed. Following the C172 programme, it was adapted for use on the larger Cessna 208.”
As it happened, the first automated Cessna 208 test flight took place in June this year, with a fully automated landing taking place soon thereafter. To find out more about the technology in these aircraft, Aviation News Journal spoke with Robert Rose.
According to Rose, “People have been flying autonomous aircraft for some time, the military has been doing this for a while, but I think what makes our demonstration unique, is we are not a military funded programme. This is private money.
“We also got approval to fly over a populated area. I don’t believe that’s ever been done before through a completely privately funded programme. But more importantly, we set out from day one with certification in mind.” He mentioned that many of the components the company has developed are certifiable. “We are now working with the faa (Federal Aviation Administration) on getting this approved for use in a civilian and commercial capacity,” he added.
Do these aircraft fly with the help of artificial intelligence and machine learning? Not quite. In the words of Rose, “There is artificial intelligence in the sense that it is an intelligent system, but it is not AI in the deep learning sense by any stretch. There is no regulatory basis for flying machine learning or deep learning systems in airplanes yet. We wanted to focus on what can be done right now.”
This does not mean Reliable Robotics makes use of a regular autopilot system. “I wish we could have bought an off-the-shelf autopilot,” said Rose. “The fact is nobody makes an autopilot that can handle all phases of flight: taxi, take-off and landing,” he added. “The other problem is that they don’t handle failures gracefully… If you’re going to automate the entire aircraft, and you’re not going to have a pilot in there, then you need something that can not only detect failures, but also respond to them immediately. So, we set out to go built it. A lot of the methodologies and principles that we’re following echo what we developed at SpaceX.”
In terms of equipment, what exactly does it take to automate a small cargo aircraft, such as a Cessna 208? “We have developed custom computers, software, mechanisms, communication systems, ground control centres, back end data network for transferring all of the data between the aircraft and the control centre…” Rose mentioned that “actuators are another thing that we have spent a great deal of time developing. You can’t buy actuators of the shelf that are suitable for automating the aircraft to this degree.”
Looking at the rate at which Reliable Robotics has achieved its milestones, it is impressive how quickly the team has made progress. “This is really a testament to the simulation capability that we have developed,” remarked Rose. “We felt from the beginning that it was of crucial importance that we build a simulation capability for our aircraft that the world has never seen before!” The team was able to model flight dynamics with great accuracy, with the result that systems worked remarkable well during actual test flights, saving a significant amount of time.
For further information, as well as more recent news on the development of autonomous cargo flights, please visit www.reliable.co
Late last year, the US Department of the Interior (DOI) grounded its fleet of more than 800 drones. This has created a tremendous opportunity for North American manufacturers of unmanned aircraft.
All of the DOI’s drones, properly known as unmanned aircraft, unmanned aerial vehicle systems (UAVS) or remotely piloted aircraft systems (RPAS), were either manufactured in China, or built with Chinese components. According to the DOI, the grounding was the result of a national security risk, as these unmanned aircraft gather, and could potentially transmit, a staggering amount of information wherever they fly. The ban on US government drones, which target products made outside North America, has opened the market to companies in the USA and Canada.
In January this year, DOI spokesperson Carol Danko said, “After an ongoing review of Interior’s drone programme, Secretary Bernhardt issued a Secretary’s order today, affirming the temporary cessation of non-emergency drones while we ensure that cybersecurity, technology and domestic production concerns are adequately addressed. Drone use for non-emergency operations will remain grounded while the Department of the Interior reviews the possibility of threats and ensures a secure, reliable and consistent drone policy that advances our mission while keeping America safe. Drone operations will continue to be allowed in approved situations for emergency purposes, such as fighting wildfires, search and rescue and dealing with natural disasters that may threaten life or property.”
The order to which Danko referred expounded on her statement, and pointed out, “In certain circumstances, information collected during UAS missions has the potential to be valuable to foreign entities, organizations, and governments.” The order also mentioned that it had been determined that “domestic production capability for small unmanned aerial systems is essential to the national defense.”
To find out more about these developments and their impact on the North American market, we spoke to Camaron Chell, CEO of Draganfly Inc, the oldest operating commercial drone company in the world. Over the years, it has established a reputation of being a pioneering company in the field of unmanned aircraft. Founded in 1998, Draganfly made its mark in history by being the first company to commercialize a quadcopter. In 2013, the RCMP used a Draganflyer X4-ES quadcopter to locate an injured man in a remote part of Saskatchewan. It was the first time in history that a drone had been used to save someone’s life. Draganfly holds 26 patents and is the first company to have a drone inducted into the Smithsonian Museum.
Chell, who has a background in machine vision-based ‘follow me’ technology for drones, has been with Draganfly since 2014. The company currently has offices in California and a manufacturing plant in Saskatchewan, but will be expanding over the next few months. Over the course of its existence, Draganfly has sold more than 9,500 drones, and will more than likely sell its 10,000th product this year.
The company conducts advanced research and development, producing fixed-wing and rotary wing drones, as well as unmanned ground vehicles or robots. The Draganflyer Commander, for example, is a comparatively small UAV, a quadcopter, which can fly at speeds of up to 50 km/h, in winds as strong as 35 km/h. It can carry a payload of 1 kg and operate in temperatures from -24°C to 38°C. Equipped with infra-red and electro-optical cameras, the Commander can be used for digital surface monitoring, search and rescue, tactical overwatch or firefighting missions. With a multispectral kit, the same quadcopter could be used by farmers for crop health assessments or by researchers to determine a normalized difference vegetation index (NVDI). If the Commander is equipped with a QX100 camera, it could be used for 3D modelling and mapping, or by law enforcement officers for accident reconstruction.
These are just a few examples of the versatility of one small remotely piloted quadcopter. The number of tasks which can be accomplished by drones in general, is simply incredible, and technology is advancing rapidly. According to Chell, “We are now getting to a point where there is enough data for machine learning and artificial intelligence (ai) are becoming practical and useful. Twenty-four months from now, I don’t think there will be a drone out there that does not utilize ai or machine vision.” Chell continued that with the advent of 5G, cloud computing will make drones even more versatile and capable. “It will help the whole drone market realize
A Time of Opportunity
In addition to addressing a national security concern, the US government’s ban on imported drones for government use seems to be targeting foreign policy, in which foreign authoritarian governments are able to obtain data from its drone manufacturers. According to Chell, “The amount of data collected by drones is off the charts.” He continued, “Incredible amounts of data is collected, which along with other data points and ai, can paint some pretty impressive security pictures.”
As a result of the ban, North American drone manufacturers now have access to a market which had until recently been dominated by Chinese manufacturers. “There is somewhere between $600 million and $1 billion of yearly revenue that is attributable to commercial drones that are on government projects, whether that is military, industrial, infrastructure, commercial, etc.,” said Chell. That revenue is now available to North American drone manufacturers who demonstrate and meet the security criteria of the US government.
With their biggest competitors banned from supplying unmanned aircraft to a major market, this is certainly an exciting time, filled with opportunity, for North American manufacturers.
Originally published in the January-February 2020 edition of ANJ.