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Whaddaya get when you cross a quadcopter with a plane? The HQ UAV


August 20, 2013

Latitude Engineering’s Hybrid Quadrotor UAV

Latitude Engineering’s Hybrid Quadrotor UAV

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If you need a drone aircraft that can hover in one spot or perform vertical take-offs and landings (VTOL), then a multi-rotor contraption such as a quadcopter is the way to go. Should you be looking for something that can cover long distances as quickly and efficiently as possible, however, then a more traditional propellor-driven fixed-wing airplane will serve you better. So, what if you want both? Well, that’s where Latitude Engineering’s Hybrid Quadrotor UAV (unmanned aerial vehicle) comes in. Putting it simply, it’s a quadcopter/fixed-wing combo.

For take-offs, landings and hovering, the HQ utilizes four horizontally-mounted propellors – just like a regular quadcopter. These are each driven by an individual electric motor, all four of which receive their power from two 5-cell 11,000 milliamp-hour lithium-polymer battery packs.

Once the HQ reaches cruising altitude, however, its vertically-mounted push prop takes over. Powered by a 0.5-hp 4-stroke gas engine, it takes the aircraft to a forward cruising speed of around 40 knots (46 mph, or 74 km/h), which it can maintain for up to 15 hours.

The UAV is controlled either by a ground-based human operator, or via its own autonomous control system. “The Piccolo autopilot allows the use of a few different forms of control, ranging from complete manual where it flies exactly like an RC plane/quadrotor to complete auto including take-off, landing and waypoint tracking,” lead engineer Carlos Murphy tells us. “We have successfully flown complete autonomous flights which include autonomous take-off, transition to forward flight, then transition back to hover and landing.”

There are actually two versions of the HQ currently in development. The latest incarnation of the first model (described above) has a composite airframe made largely of carbon fiber-skinned foam and balsa wood, along with ABS plastic. It weighs in at 25 lb (11.3 kg), and can carry a payload of up to 2 lb (0.9 kg).

More recently, work has begun on a larger, pure carbon fiber-bodied HQ. It weighs 60 lb (27.2 kg), carries 8 lb (3.6 kg), and has a 5-hp engine that should hopefully keep it aloft for up to 24 hours. Additionally, along with the four lifting propellors on the top surface of its airframe, it has an additional four located on the underside – this makes it an “octocopter,” so to speak.

This larger model is being developed under a contract with the US Navy and is scheduled for delivery within the next month, for subsequent field tests. It is expected to sell for around US$60,000, with the 25-lb version coming in somewhere around $25,000 to $30,000.

Finally, some readers may be wondering why Latitude didn’t just go with a tilt-rotor design. According to Murphy, there were three main reasons: the HQ design is simpler, requiring fewer moving parts and thus offering increased reliability; any small weight penalties of the design are offset by its advantages; and, its dual gas/electric propulsion system allows the UAV to stay in the air longer.

This last point is due to the fact that while the high power output of the electric motors is used to get the HQ airborne, gasoline’s superior energy density (as compared to that of batteries) comes into play once the aircraft starts traveling forward. “When you make a tilt-rotor all electric powered, you need tons of batteries if you want endurance,” Carlos explains. “If you want a high-endurance gas tilt-rotor you need (for the sake of argument) a super-charged V8 to take off, while during forward flight all you need is a tiny little inline 4 ... vertical take-off and forward flight have pretty much mutually exclusive requirements when it comes to power sources.”

With the HQ, he says, “you are always flying with the correct power source for the job, VTOL or conventional flight.”

Source: Latitude Engineering via Popular Science

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

I love this design! It's just a brilliant, yet simple concept, and very well executed. This one is worthy, IMO, to be taken to the next level as a human-carrying transport... In fact, I think you're looking at the future of personal air transportation, folks. Solve the wing retraction / folding challenge (can't have that huge wingspan sitting in my driveway, eh?) and this baby's ready to haul my traffic-jam-hating butt to work and back every day! Bring it on!


Having 5 engines with 80% of them dead weight 95% of the time to travel is not an efficient future transportation. But if its need is 90% a hover function, then its a very versatile UAV with legs to come home quick and safely after lurking over a point of interest. Transforming geometry frames can use minimum engines all of the time in both worlds.

Tristram Metcalfe

It seems to me that tilting rotors would be less weight and have already been tested extensively on manned planes. The tilting rotors can take off and land and hover and then tilt forward to speed from place to place. When you think about it, isn't this what the quad copter concept does already? The entire copter tilts forward to speed from place to place. Is the speed limit of quadcopter less than what this new version offers? If you need more flying time, a gas engine could be used in hybrid fashion. Just thinking. L.


The tendency to over-design, always looking at expanding mission capabilities, takes away from the concept of low-cost single purpose/dual-purpose design that led to the current highly efficient and now fearsome capabilty of Drones. Not to say that weaponsized drones haven't served a needed purpose, but increasing the cost geometrically somewhat obscures the original surveillance intent of gathering intelligence on targets and "persons of interest" for military forces to capture or destroy. The adoption of simple surveillance drone capability on U.S. borders, particularly in the South, and the performance to date, bodes well for using technology to improve performance and reduce costs.

Barry Dennis

Ok it's cool. But I do not see the need for vertical flight in navel usage. Given it's size and operating speed a fixed wing could easily be operated off a helipad. Just add a small magnet to the nose gear to hold it in place while the crew member walks out to collect it. Given that it can be operated by remote control the computer that lands the thing does not need to be on it.

@ Tristram Metcalfe

Using propellers in excess to needed power is highly inefficient and the weight increase to make the electric motors capable for continuous operations would further decrease efficiency. This is a great design for what it does I just don't see the need it has for vertical operation in naval operations.


Modern batteries have roughly the same energy density as fuel, so that argument is not valid.

Quad technology is very established, thus mature, and simple, although scaling up doesn't really work. To lift a big camera you need octocopters, at least, and to lift humans you need even higher numbers of props and motors!

So a simple solution is a glider with an Internal Combustion engine, combined with a quad, just what we got here!

An airplane with a single, oversize, engine, with contra-rotating propellers, will be a much better solution, mechanically, and technically!

More efficient every way, and less complex!

Tord Eriksson

Rubbish! This is much much better


@Slowburn: I think the idea here is that quad-rotor hover capabilities are just as useful while on target as they are during take-off and landing.

@Tord: I'm not sure where you're getting your energy density information from, but check the chart at ... a bit of a difference there. Lets just say that batteries have a loooong way to go yet...

As to incorporating a tilt rotor system, that could be a more efficient option, but not as simple or as "off the shelf" for scaled down models such as this UAV. The idea here, I think, was to combine to proven techs for "model" aircraft into one hybrid design that provides the advantages of both with minimal efficiency loss: electric for VTOL and liquid fuel for cruise. Could the cruise engine be electric as well, with a backup ICE for generation? Sure, but again, for this kind of vehicle you're getting into some un-proven (as in not established, widely utilized) technology that, while this company may have plans to develop, doesn't make for a current product to sell today.


@ Tord S Eriksson Energy density of Petrol: 47.5 MJ/kg and 34.6 MJ/liter; Engery density of lithium-ion battery pack: 0.3 MJ/kg and 0.4 MJ/liter


@ MzunguMkubwa

At that size I have real trouble seeing any task that the navy would use that hovering will do a better job than flying in tight circles.


I wonder what happened to the FanWing, and if paired units (one behind the other) with some interesting flaps could provide both lift and flight?

Bruce H. Anderson

@Bruce, I've often wondered why Peebles hasn't pursued that layout with his fanwing concept. A dual axis configuration would allow the fanwing mechanism to control pitch & roll by regulating throttles and ailerons, along with a couple of vertical control surfaces positioned within the exiting airflow for yaw. Getting creative with flaps/thrust-vectoring then allows (at least) very slow yet controlled flight, if not hover.

I always thought that he should abandon the notion of hover & VTOL (his website claims some development of this) in favor of just very slow & controlled forward flight, with very high angles of approach. Dual axis/wings could allow this kind of flight behavior making for a very flexible, stable, and user-friendly flight platform.


"Modern batteries have roughly the same energy density as fuel, so that argument is not valid."

Tord, I agree with the others. Batteries are nowhere near the energy density of fuel and probably never will be. The Volt battery weighs nearly 1,000 pounds and only holds the power equivalent of less than one gallon of gas. 1,000 pounds of gasoline would run the Volt more than six thousand miles, the 1,000 pound battery is lucky to take it 30 miles.

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