SureFly prototype
11 min read

I have seen the future, and it works… sort of. The SureFly looks a little like an upside-down octopus, but this hybrid gas-electric octocopter is striking nonetheless. It also represents one of the most interesting ideas in light aviation right now, with a unique mix of big ideas and pragmatic engineering.

Somewhat surprisingly, this vision of the future is sitting in a warehouse in Loveland, Ohio, not Silicon Valley. While many of the biggest names in technology, from Google to Uber, work on radical concepts for VTOL (vertical takeoff and landing) aircraft, SureFly’s small team of engineers and pilots plugs away on their own concept in relative obscurity. They may even be farther along than some of their more famous competitors.

HorseFly drone with truck

Where the idea came from – the HorseFly.

Workhorse, the company behind SureFly, has been a pioneer in developing electric trucks for commercial use, including a $50,000 pickup you can order today. One of its most important projects is a next generation UPS delivery truck that includes a roof-mounted drone for “last mile” delivery. Work on this drone got the company interested in VTOL aircraft and electric motors.

A hybrid design

The result is something much bigger than a drone – a total rethink of the helicopter, based on electric motors and computers instead of mechanical controls. While a modern helicopter is an amazing invention (I know, I fly one), it is very much a manual machine. Even in highly automated turbine helicopters, the pilot is still controlling the pitch of the blades, the speed of the engine, the pitch of the tail rotor, and a whole lot more. Unlike a drone, which will hover quite nicely with the pilot’s hands off the controls, an inattentive helicopter pilot can quickly crash because the machine is inherently unstable.

Many of these assumptions change with SureFly, mainly because electric motors deliver impressive torque and can change speed almost instantly. So instead of a centrally-mounted engine connected via lengthy driveshafts to a main rotor and a tail rotor, the SureFly has eight electric motors, stacked in pairs on four carbon fiber arms. Each motor sits right next to a fixed pitch propeller – four pointing up and four pointing down.

Like a DJI Phantom on steroids, the flight path is controlled by changing the speed of the eight motors, sometimes hundreds of times per minute. This requires serious computing power and sophisticated software, but it eliminates fully articulated rotor systems, tail rotors, gearboxes, and complicated mechanical controls. It also allows for that hands-off hover, which is perhaps the holy grail of electric, multi-rotor aircraft.

Electric motors bring other benefits, too, including a reduction in noise. While some boosters overstate this effect, the engineers at Workhorse believe the SureFly will be significantly quieter than a traditional helicopter (and early testing backs this up). That’s a critical feature for making intra-city transportation dreams come true, where the complaints of neighbors may matter more than the FAA rules.

SureFly prototype

Not your typical helicopter.

Electric motors can also be stopped almost instantly. This makes it much faster and easier to load and unload the helicopter after landing. Instead of waiting for the blades to stop turning, passengers can jump out of the SureFly just seconds after touching down; the pilot can then start right up and take off. That should make multi-leg air taxi routes or package delivery scenarios much more efficient.

Flying the aircraft will be an exercise in systems monitoring, not old school stick and rudder. The cockpit has no collective lever and no traditional cyclic, just a single control stick in the center. Point the stick forward and the computer asks the rear motors to spin faster than the forward motors, tilting the helicopter forward. It’s the same basic idea of a helicopter’s rotor disk, but with no swashplates or pitch links.

The panel consists of a single screen that includes all flight and engine instruments, so it does feel almost like a video game. John Graber, an experienced military and airline pilot who has flown many hours in the simulator and is the lead test pilot, says he believes a pilot can learn to fly the helicopter in just a few hours.

When the SureFly is done working for the day, its four arms will fold for compact storage. The goal is to fit in garages and barns, but also trailers. That means it can be transported to the most convenient base of operations. With a 70 mph top speed and one hour of endurance, this is hardly a cross-country cruiser. Almost the entire aircraft is made of carbon fiber so it’s light: 1100 lbs. empty and around 1500 lbs. at max takeoff weight.

Being realistic

A lot of this sounds ambitious, and it certainly is. But a look beyond the headlines shows some thoughtful and realistic decisions – especially when compared to higher profile ventures.

Consider the two trends that are driving most of the futuristic designs right now: all-electric power systems and autonomous flight. Workhorse believes in both of these trends, but only in the medium to long term; over the next five years, neither of these dreams will be realized for passenger flights. This insight (or perhaps admission of reality) is one of the most refreshing things about the SureFly team.

Start with batteries. While some companies, notably Boeing, are betting on transformative changes in battery technology to enable all-electric aircraft, Workhorse founder and CEO Steve Burns isn’t buying it. Sure, battery prices are coming down quickly, but that’s not the issue. The energy density of batteries will have to improve dramatically in order to make all-electric aircraft a reality. Those advances are possible, but almost all are still in the lab, years from commercial availability. For that reason, SureFly is using electric motors but two gasoline generators to drive those motors. Workhorse has essentially separated the issues of electric propulsion and electric power sources.

Whereas the company’s trucks run on electric as primary and then switch to a backup generator to extend range, the SureFly flips this around, with a large battery mostly there to even out power spikes and provide quick power boosts when needed. It’s also backup, providing five minutes of power to allow a safe landing in case of engine failure.

SureFly cockpit

The cockpit might eventually carry two passengers – and no pilot.

Other safety features include a ballistic parachute, which is only possible because of the four-arm design. This can be used above 350 feet; below that the SureFly can continue flying with the loss of one of its eight motors, although only to a forced landing site. There is plenty of redundancy here, but the overall goal is simplicity. You won’t find any tilt rotors or ducted fans here like you will on the new Airbus VTOL machine.

The realistic approach to batteries is matched by a conservative plan for autonomy. While two passengers instead of one pilot and one passenger makes the economics a lot better, that is pretty far out on the SureFly roadmap. The computer on board is flying the aircraft, and this could certainly be controlled remotely instead of from the left seat. For now, though, that would present additional technical and, more importantly, certification challenges. The FAA is struggling to figure out a standard for electric motors; Part 135 charter with no pilot seems almost laughable compared to that.

Is it certifiable?

That concern about certification is ever-present: even if the SureFly design is sound, that hardly guarantees it will be certified. Will the FAA play ball? So far signs are encouraging. Everyone I talked to at Workhorse had praise for the FAA staff they have worked with, and this went beyond mere politeness.

Recent changes have combined to make this a fortuitous time to certify a radical new aircraft. Most notably, the multi-year effort to update Part 23 certification standards is finally taking hold. Phrases like “equivalent level of safety” are being used much more often, while rigid interpretations of old policy letters seem to be fading. The impact has been on FAA culture more than just rules and regulations.

The FAA also feels a certain sense of failure at stumbling out of the starting blocks with the drone boom (many other countries have zoomed past the US in terms of drone development). This time, they want to get it right. A small but telling example is whether there are eight “engines” and eight “propellers” on the SureFly, with each one requiring its own logbook, or a single drivetrain, so one logbook will suffice. So far, the FAA has decided on the latter. That’s progress.

Of course it’s not all smooth sailing when you’re certifying a new aircraft. The cockpit features two throwback instruments: a magnetic compass and a standalone altimeter. Both were required in order to earn a special airworthiness certificate (experimental), which the SureFly received last month. Other such “box-checking” requirements are sure to pop up.

Training will also require some open-mindedness from both the FAA and the insurance industry. If this is a helicopter, does it require 50 hours of training, like a Robinson R22? The helicopter Airman Certification Standards don’t seem to fit the SureFly very well either, so how will a checkride be conducted? It’s fair to say nobody knows the answers to these questions yet.

Making money

Certification is one hurdle; financial success is another, as countless aviation companies have learned over the past 50 years. As an industry maxim goes, “the type certificate is not the finish line, it’s the starting line.” Workhorse owns an auto manufacturing plant in Indiana, where it makes its own trucks from the chassis up, so this company is not naive about the challenges of manufacturing. That should give them a leg up on startups that only know engineering and venture capital. Workhorse also has over 400 dealers in place for their trucks right now, many of whom might someday offer a helicopter as well.

Workhorse truck

Workhorse already manufactures an electric/gas truck, so they are no strangers to production planning.

But finding customers for a new and unique looking product is never easy. While the popular press has written sexy headlines about “a new generation of flying cars” or “the ultimate millionaire’s toy,” neither of those hold much promise in the short term. Uber certainly has big ideas about moving millions of people around by air – indeed, this is what has caused so many VTOL startups to be founded over the last year – but other applications are much more realistic.

For Workhorse, commercial users are the focus, including local delivery companies, law enforcement agencies, agriculture, military, and yes, some passenger transport. Many of these buyers are not aviation companies in any traditional sense of the word, so the compact storage and simple flying traits will be major selling points. As CEO Burns says, their goal is not to take some share of the 900 airframes/year helicopter market, but to convince companies who would never consider a helicopter to buy a SureFly.

The competition will be stiff, with famous names like Airbus and Bell Helicopter actively testing competing ideas. Burns hopes to beat them on both speed to market and price, since many other programs are focused farther out in the future, with moonshot designs and business models.

How much for this revolutionary new machine? The Workhorse website, which is accepting $1000 deposits, advertises a “Target price under $200,000.” That certainly leaves a lot of room to wiggle, and it wouldn’t shock longtime pilots if the price approached the R22’s $300,000 level. Even still, the SureFly would still represent a significant advance in both operating cost and ease of use.

First flight took place this month, and production is scheduled to start in 2019. Like any new aircraft program, that date, along with the price, should be considered goals and not guarantees. Reaching the finish line will require patience, luck, and (perhaps more than anything) money. To keep the funding flowing and to focus on the distinct business units, Workhorse plans to spin off SureFly as its own company this summer, traded on the NASDAQ.

Whether SureFly makes it or not, the technology it’s using will remain, not least for future general aviation airplanes. Electric motors and computer control really do change things, especially if the entire aircraft is designed around these ideas. Indeed, Graber sees some parallels with the early days of Cirrus Aircraft, a comparison that isn’t quite as ridiculous as it sounds if you know your history. A small engineering team in a midwestern city trying to use composite construction and ballistic parachutes to shake up a staid industry – can lightning strike twice?

John Zimmerman
12 replies
  1. John
    John says:

    Anyone know if, like Cirrus, they’re going to use a chute from BRSI (another publicly traded company). Very interesting stuff. …Kids got a cheap drone for Christmas and yep it does a good job of hovering on its own… amazing technology. still not as fun as a 172 though

  2. Curt Jacobsen
    Curt Jacobsen says:

    Mr. Robinson:

    In a word: disappointing.

    I know that journalists in this industry don’t normally take an aggressive adversarial position in these kinds of articles, but why aren’t there more critical questions?
    Take for example power requirements for this thing. With very small overall swept rotor area, the lift efficiency will be awful. You don’t need to design rotorcraft to know this; the data is out there for you to find. Assuming four 2m rotor discs (doesn’t matter that there are two props in it), the disc loading will be ~54kg/m^2. (This is not some kind of guess; it’s just math). Known performance metrics for hovering tells us that this means lift efficiency will at best be as good as a tiltrotor, or about 4.5kg/kW. Again, this is not magic knowledge; it’s empirical data based on decades of rotorcraft design and you can find it yourself easily. This means total shaft input power will be about 150kW.

    Work backwards through known efficiencies of motors, power electronics, rectifiers, generators and gearbox and you get somewhere in the range of 210kW engine shaft output. For all us Americans that means an engine making 280hp.

    And a fixed-disc pitch multirotor gives very little translational lift (even then only at low forward speed) so to go 70mph requires a 300shp engine. The engine installed in the “demo” aircraft is a Honda turbo automobile engine that shows up as Viking in the homebuilt universe, but only in 130hp trim. This engine will never be certified.

    Workhorse stated in AINonline that they really need a 300shp gas turbine or rotary. A 300 shp rotary does not exist in any certificable form, but the 300shp gas turbine does: a RR300 as installed in the R66.

    Does that begin to make sense? The same engine as a 4-seat helo to run this little thing? 20gph+ to carry two people at 70mph? Could you ever build a fully-FBW aircraft with this engine and sell it for $200k?

    There are many other holes in this story and frankly you should have pointed them out or not published. Workhorse is trying to sell shares. They just used your article to con the public. Bad stuff, sir.

    • Dave Newill
      Dave Newill says:

      Curt J has done a good job of analysis – very similar to my white paper on the broader subject of Electric Aircraft. I did sit in Workhorse and talk to their engineers – and they know of the need for a RR300 type engine just to make it work – and burn a certified aviation fuel.

      A paragraph from the longer report does add some hope to the possibility however of these designs –
      Commercial Drones – For a bit of fun – go fly a drone! Now Remote Control model aircraft had existed since the 1950’s but it was in 2003 that the combination of lightweight and easily chargeable batteries combined with acceptable electric motors and new lightweight airframe materials made this hobby do a true about face. In less than 10 years, glow-ignition engines were practically eliminated from flying fields…and then came the four rotor drone. The Parrott AR was first and introduced at the Consumer Electronics show in 2010. While there had been many R/C helicopters before this, the electric quad-rotor configuration, cell phone screen touch controls, micro auto-pilot controls and new materials released the industry – and Chinese manufacturers in particular – to offer four, six, eight head rotor machines (some with double propellers) to a very willing public. Since 2010 some four to six million non-toy drones have been delivered. DJI, the leader with >35% of global market, sold over 2.2 Million in 2016. Some 825,000 were delivered in the US alone that year. What a change in 15 years for hobby flyers!

      One should not discount the rapid change that could happen in certain markets if the right combination of consumer demand, workable technology and novel design come together.

    • Matt Maschinot
      Matt Maschinot says:

      You do understand that the engines are electric, and that the gasoline engine is strictly to produce electricity, to charge the battery, and not to power the engines – don’t you?

      • CincyFlyer
        CincyFlyer says:

        Matt, the engine runs a generator which then directly powers the motors. The battery technically isn’t needed.

  3. Curt Jacobsen
    Curt Jacobsen says:

    Also, the latest rulemaking document published on FAR Part23 rewrite is here:

    The Uber Elevate technologists and industry particpants believe this will be sorted out to a genuine rule set by the end of 2018 (optimistically).

    How in the world does that translate to a Producton Certificate for the SureFly for 2019 deliveries?

    You’ve been lied to.

  4. Roca
    Roca says:

    I’m always excited to see new tech on the horizon…but at the same time I will lament the death of traditional helicopters. Flying a helicopter…FLYING it, not programming it…is one of the great joys in my life. You must become one with the machine in a way that you don’t with most airplanes. I sure will miss it.

  5. Tom Yarsley
    Tom Yarsley says:

    Historically, the FAA’s attitude about ANY new technology has been akin to requiring that electric light bulbs must adhere to regulations that govern the manufacture and use of candles.
    Is that changing? We’ll see.
    In the meantime, economic viability of such a vehicle will require full autonomy – it’s just not practical to devote 50% or more of your payload to an on-board “pilot.”

  6. Ron Oliver
    Ron Oliver says:

    Lots of talk but no video of this thing doing anything. Just a picture of it sitting on the ground. No specs on performance such as max speed, fuel burn, engine specs., or anything that might make a pilot’s heart go thump. From what I do see, this company’s R & D has a lot of work to do. I would like to see the REAL stuff that tells me this is a practical idea. As for now, that’s all it is…….an idea.

  7. Bob Matson
    Bob Matson says:

    Curt Jacobsen
    Excellent observations. You have to believe the math. Their plans for this machine however demands the usual scrapes along the way, and I am inspired by the abundant creative activity in this and many other similar battery EV projects. I wish them well.

    Bob Matson

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