Over the last few years, we have witnessed the rising phenomenon of electric drones (EDs), also referred as multi-copters or civilian unmanned aerial vehicles, available at competitive prices on the market. The growth in drone sales is so far exponential, which implies their increasing penetration into existing drone markets of (photography, security and toys) and more importantly the resulting industrial evolution, which could allow drone introduction into additional fields. This study aims to compare the physical properties of electric drones (EDs) with small-scale internal combustion aerial vehicles (ICAVs) and more broadly draw the technology trend of electric-powered drones, in order to project their future integration potential.
Over the last few years, we have witnessed the rising phenomenon of electric drones (EDs) also referred as multi-copters or civilian unmanned aerial vehicles, available at competitive prices on the market. Consumer electric powered drones have become a reality as a result of maturity of a number of technologies including Li-ion batteries, GPS navigation, light-weight microelectronics, wireless communications and lately also machine vision and autonomous flight functions. This is of course coming in addition to the more mature technologies of gyroscopes, servo-motors and flight-control. As of 2015, the leading market for civilian drones was US (35% of total), with European Union closely following (30% of total) and China on the third place (15% of total). Estimated global sales of civilian drones reached about 4.3 million units for the time, worth some 1.7 billion USD, which makes it a pretty impressive market, with a high potential for further growth. Drones have become to be viewed as a truly disruptive element within multiple areas over a very short period of time. It is still unclear what would be their true impact on freight, agriculture and transport, but they have already become irreplaceable in the fields of security and photography.
This analysis aims to compare the physical properties of EDs with small-scale internal combustion aerial vehicles (ICAVs) and more broadly draw the technology trend of electric-powered drones, in order to project their future integration potential. For the purpose of this study, the data of ten selected EDs has been utilized, based on the "Best Drones of 2017" publication by PCmag, updated for June 2017. With lack of model-specific information on sales, the drones were equally weighted to obtain averages for ED weight, battery's watt-hour capacity and rated flight time. The surveyed EDs included models under brand names of DJI, Parrot and Yuneec. The comparison of ED was made versus an ICAV - the gasoline-powered toy helicopter Century Radikal G20 with 300ml fuel tank. The weighted average with standard deviation of EDs is depicted on the following charts in comparison to parallel figures of ICAV. The energy content of gasoline was rated in watt-hours for proper comparison to electric batteries.
Figure 1. Average flight time (minutes) of popular electric drones in comparison to ICAV, represented by Century Radikal G20 model.
Perhaps the most important conclusion of 2017 analysis is the beginning of direct competition of EDs with ICAVs in terms of absolute flight time. The significant increase of weighted ED flight time is coming due to introduction of winged EDs, which show a dramatic increase in performance - exceeding other drones and way exceeding the energy efficiency of ICAVs. Parrot Disco FPV for instance is rated with 45 minutes of flight time, significantly exceeding both DJI Phantom 4 Advanced and DJI Phantom 4 Pro with eating of 30 minutes each. In case this trend continues, we might well be seeing the beginning of the demise of fuel-powered lightweight airborne vehicles.
Figure 2. Rated aerial vehicle flight-time-per-weight (min/kg) of EDs in comparison to an ICAV, represented by Century Radikal G20 model. The flight-time-per-weight can serve as a measure for normalized comparison of flight time.
The flight-time-per-weight is a fair parameter to analyze EDs performance and compare them to ICAVs in terms of flight time, while neutralizing the size factor. The best ED flight-time-per-weight in 2017 was held by winged Parrot Disco FPV with 60.00 min/kg, whereas the least impressive flight-time-per-weight was obtained by DJI Inspire 2 with just 6.50 min/kg. ED weighted average flight-time-per-weight remained stable during 2015-16, but experience a dramatic spike in 2017, mainly due to the introduction of highly energy packed Parrot drones, where battery's weight is a notable share of total drone weight coupled with high-performance flight qualities. The gap between ED and ICAV models in terms of flight-time-per-weight is actually in favor of electric-powered units due to their superior energy efficiency. This also explains the sudden emergence of efficient and cheap electric drones, whereas gasoline-powered unmanned vehicles have historically been inefficient and expensive.
This flight parity analysis of electric-powered drones indicates a much more efficient propulsion system of EDs in comparison to ICAVs, as EDs are rapidly closing on ICAVs in terms of absolute flight time. EDs are already superior over ICAVs in terms of weight-normalized flight time. This comes despite the much higher energy capacity of ICAV units, which gets wasted due to very low efficiency. In summary, as of 2017, mainstream EDs seem to be greatly superior over niche ICAVs, which might soon disappear.
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