Drone aircraft are capable of doing great good, ranging from faster pizza delivery to replacing jet transit for distances less than 1000 miles. More specifically, only Vertical Takeoff and Landing drones (aka, VTOL drones) capable of transitioning from rotary-wing flight to fix-wing flight will provide the critical combinations of access, energy efficiency, and speed to do this good.
A starting point this project is to assemble and demonstrate a simple, but very effective, transitioning drone technology referred to as the passively-adjusting tiltwing quadcopter. Advanced projects would include modifying and printing structural components for assembly into new versions of the passively-adjusting tiltwing quadcopter. Optimal designs likely like in other milticopter variations which would be for advanced levels.
Here, flight theory is reduced to rules of thumb ("heuristics") to allow people of diverse backgrounds to make significant progress on drone design. There are a number of inaccurate presentation of flight theory, the persistence of those inaccurate theories (muddied waters, impact on commercialization) presents unique opportunities for student projects to fabricate drones that can out-perform the best commercial and military alternatives. The initiating heuristics are:
Transitioning VTOL drones take off with the rotary wings (and/or propellers) oriented upward and pulling the drone upward, after which, forward velocity is initiated with two transitions occurring: 1) vertical propulsion is increasingly replaced with forward propulsion and 2) wing-based lift increasingly replaces rotary-wing lift. Many transitioning VTOL drone approaches are used to perform the two transitions. The Passively-Adjusting Tiltwing stands out from the crowd because the transition happens with the use or need of any motors (or other electronics) beyond the four electric motors of a quadcopter.
The Passively-Adjusting Tiltwing is comprised of one or two propeller-motor units connected to a wing where that wing has shafts/bearings that allow it to turn from an upward orientation to a forward orientation. In the absence of oncoming air, the weight causes the the tiltwing's propeller to point upwards. Impacting air tilts the propeller in a more-forward orientation, with the goal of higher velocities causing a transition to fully fixed-wing flight.
The most basic project (Option A, see next sections for advanced projects) involves 3D printing the platform and transfering the electronics from a "ready-to-fly" drone to that new platform.
This project requires: a) 3D printing of HS-Drone platform parts; b) purchase of a quadcopter with remote control; c) removal of propellers, motors, control card, and connective wiring from the purchased quadcopter; and d) assembly of the printed parts and scavenged electronics into a completed quadcopter similar to that of the adjacent figure.
a) The STL files at http://www.terretrans.com/project-stl-files.html may be downloaded and printed to provide: 1) a fuselage with two rear arms, 2) the tiltwing's wing with two slide-mount guides to attach motor mounts, 3) two forward motor mounts that slide onto the tiltwing's wing, 4) two rear motor mounts that attach to the ends of the arms of the fuselage print. The STL files may be outsourced for printing by a 3D-printing service provider.
b) The quadcopter from which electronics are scavenged for this project is the SNAPTAIN S5C WiFi FPV Drone available at amazon.com. Clean off the prints (use a box cutter and/or sandpaper) so as to assure the shafts on the forward motor mounts will rotate in the inbuilt bushings of the forward arms of the printed fuselage.
c) The small screwdriver provided with the Snaptain quadcopter can be used to remove the top half of the fuselage and then remove all four motors and the control card with all wires and functionality intact. Cut the plastic mounting plate of the control card from the bottom of the fuselage.
d) Use the screws removed from the Snaptain quadcopter to attach the rear motor mounts to the fuselage arms and the front motor mounts to the tiltwing's wing. Then squeeze the front arms of the printed fuselage together sufficiently to place the bearings of the titlwing into the bushings of the front arms--pursue a method of minimal squeezing/tension on the front arms. Trim the plastic mounting plate of the control card so the mounting plate can be taped/glued/screwed onto the mounting plate support of the printed fuselage. Screw the four propeller blades and control card onto the assembled 3D-print in the same positions as removed from the Snaptain quadcopter. Tape any loose wires as deemed appropriate.
e) Disclaimer - This project is made as a free service. The provider makes no claims to the ease with which one is able to follow through on construction. The provider makes not claims to the safety and/or ability to safely operate the final product. Any user of the resulting product is to take precautions as they deem necessary and without any actual or implied warranty or ability to safely or legally operate by the provider.
f) FEEDBACK and further ASSISTANCE. Feel free to contact G. J. Suppes at email@example.com to provide feedback or suggestions on how to make this a more effective project. This web page will be periodically updated based on that feedback.
A functioning drone as assembled based on the previous instructions is the starting point for possibilities limited only by the time and abilities of the student and/or team. For a project on 3D printing novel drone platforms, three options exist for completing the drone with battery-powered electronics:
Option A - Scavenge Electronics from Ready-to-Fly Quadcopter: Advantage of inexpensive and quick results. Disadvantage of lack of ability to fly outside the performance limits of original drone including inability to exceed limits of power output.
Option B – RC Airplane Manual Control: Advantage of straight-forward circuitry and avoiding PID control. Disadvantage of limited to one or two propellers vehicle(s), and only practical on some di/bi-copter designs (see dicopter configuration of adjacent figure).
Option C – Multicopter PID Control: Advantage of providing the quick and autonomous responses needed for simultaneously power three or more motors/propellers. Disadvantage of requiring computer and software to interface with drone control card and more-complex circuitry. (see quadcopter configuration of adjacent figure).
For Option B, the following are example components (available from horizonhobby.com): DX6e 6-Channel DSMX Transmitter Only (~$170), AR620 6-Channel Sport Receiver (~$40), HS-55 Ultra Micro Servo (2 X ~$11.50), Avian 30 Amp Brushless Smart ESC (2 X ~$30),Thrust VSI 11.1V 1500mAh 40C 3S LiPo Battery: EC3 (~$30), KX80 80W AC/DC Charger (~$ 50), Motors (2 X ___). Propellers and rudders/flaps are even more-specific to the design than this component list and may be 3D printed. More to come (videos, performance data, STL files).
5) The Sky is the Limit:
The standard (metric) of a good aerial vehicle (for present purposes) is a high lift-to-drag ratio (L:D).
For jets, lift corresponds to vehicle weight and drag corresponds to fuel consumption. Therefore higher L:D correspond to less fuel consumption per passenger on an airliner. A good L:D for a jet is 18:1.
For helicopters (quadcopters, tricopters ...), the propeller(s) push air downward, pressures push/pull the propeller(s) upward, and the propeller shaft pulls upward on the fuselage. A helicopter has a L:D near 4:1.
For rockets, burning fuel increases temperature which causes high pressures to develop in the combustion chamber. Gases are directed downward through a nozzle surrounded by a "bell" where forces push upward on the bell resultant of the air accelerating downward though the bell's open end. The net result is an upward pressure on the bell; the bell transfers the force to the rocket body.
Examples of devices used to preserve desired pressures include: 1) wider wingspans, 2) optimal curvature of propellers, and 3) the use of a "bell" on a rocket as opposed to a simple hole for the nozzle.
An effective quadcopter or tricopter technology that offers both vertical takeoff/landing and cruising at speeds/efficiencies of airline aircraft will be transformative. Airline aircraft are among the most energy efficient transportation option (at about 53 passenger mpg).
6) Improving the Basic Quadcopter:
The standard quadcopter suffers from three design approach flaws which will tend to keep these "standard" quadcopters in novelty/toy applications rather than expanding to major passenger, parcel, and IT (information) applications.
i) Firstly, quadcopters rely on propellers to provide lift rather than wings or lifting bodies resulting in maximum L:D ratios near 4:1 (cruising). ii) Secondly, the discs (circle of propeller rotations) are relatively small resulting in lower efficiency than helicopters. iii) Thirdly, when cruising, the fuselage pushes/pulls air upward due to its nose-down orientation (further reducing the L:D). The bottom line is that standard quadcopters are both inefficient and relatively slow; significantly limiting their use beyond novelty applications.
An advantage of the quadcopter is its simple electronics and control logic where four motor speed provide a wide range of maneuverability.
To make the quadcopter and tricopter viable contenders for major commerce markets, three features need to be implemented: i) it must transition to wing/fuselage-based lift rather than propeller-based lift, ii) the fuselage/body must be nose-up and incorporate lifting body design with lots of surfaces at 1 to 4 degrees from horizontal, and iii) simple controls/hardware must be preserved.
HS-Drone is a start-up company product. The R&D company is Homeland Technologies, LLC. Technology is patent-pending and available for licensing.
Current R&D is a progression of technology demonstrations emphasizing 3D-Printed fuselages with a standard controller and electronics. The current goal is to attain a 75% transition from hover to cruise (prop-based lift to body/wing lift) having 2X the efficiency of other quadcopters (when cruising) while only controlling four motor speeds.
Next will be controller card programming to allow 100% transition to body/wing lift and 4X the fuel economy of quadcopters. For this, 3 motor speeds and 3 other actuators will be needed.
It could easily be the single-greatest impacting technology to reduce greenhouse gas emissions this century. Contact at: firstname.lastname@example.org