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?

History

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.

The future

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.

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.”

Draganfly
 
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
its potential.”
 
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.