Voting Results

Votes: 93
Voting Result: 2.99390243902439

Overview for SpeedQuad

Description : The SpeedQuad is a tandem wing aircraft drone with VTOL capacity. The mission of the SpeedQuad is to deliver medical product when other mode of transportation are impractical, when delivery time is critical or in any other emergency situation. I was inspired by the initial Airbus drone design, the Rutan Quickie and the Viking Dragonfly aircraft. The configuration : I have considered the flying wing, the tandem wing, the canard, the three surfaces and the classic configuration.With the tandem wing, the lift is distributed on the two wings. For a given wing area and aspect ratio, the tandem configuration have a smaller total width.Thank to that, we have less inertia in the forward axis, thus the drone is more agile. Plus, it's more compact for easier ground operation.The downside of the tandem wing configuration is that the rear wing is in the wash of the front wing. That’s why the SpeedQuad has a vertical gap between the two wings, like on the Quikie and the Dragonfly aircraft. Aerodynamics : I've research the different airfoils used on the Quickie and I decided to use these airfoils : The LS(1)-0417MOD for the front wing and the Eppler E1212MOD for the rear wing. The SpeedQuad have the equivalent of 4 meters aerodynamic wingspan. The wing loading of the SpeedQuad is around 31 kg/m2 and the cruise velocity around 35 m/s. This speed is a compromise between the efficiency and the effect of the 10 m/s front wind. The lift to drag ratio is around 14.9 at 35 m/s with the Airbus frame sheet and around 18 at 40 m/s with the XFLR5 software. I took the ratio of 14.9 for any calculation. The wing area is around 0.8 m2 and the fin area is around 15% of the wing area. Another thing to take in consideration, with a front wind of 10 m/s, we need a range of 128.6 km and 77.2 km for the 3 kg and 5 kg payload. Mechanics : The structure will be in composite material. The front part, fin part and top panel will be in glass fiber because this is enough for the structure, and it let radio waves pass through. The fuselage, wings and rotor mounts will probably be in carbon fiber, but we need future study with finite element methods in mechanic resistance, vibration and aeroelasticity to confirm this. The bottom panel (or cargo bay) will be in ABS plastic (easy to manufacture). In addition to that, we can use "nid d'abeille" structure in the wings, and an internal structure in the fuselage made of ABS. About the waterproofness, the wings, motor mounts and fin part will be open to external humidity (motor and controller are waterproof). Only the fuselage and the front part will be hermetic to external humidity. I've a used a wheeled trike landing gear because the drone will be more stable on any ground, and the drone will be able to do horizontal take-off and landing (emergency or normal operation). The SpeedQuad can easily be disassembled by two operators. The maximum length is under 2 meters and the parts can easily be transported. Electric Systems : For VTOL motors, I've took the T-Motor U11, this motor can lift 7,5 kg / motor, it's waterproof and dirt resistant, that's great for the rain resistance requirement. Between the "Power Series" and "Efficiency Series", I've chose the power, because we need to hover for only 2 min, so, I think hover efficiency isn't critical. For the rotors, I was looking for a 28 inches propeller. I've took the T-Motor 28x9.2 propeller. The rotors are positioned around the gravity center. For the cruising propulsion : I've chose the T-Motor U12 with a 30 inches propeller. It have around 11 kg max trust (at 0 m/s), 3900 max RPM and 4000 N.m max torque (at 3900 RPM). The battery is made from Kokam  Ultra High Energy NMC cells. The cells have an energy density of 265 Wh/kg (on the paper). I've chose to take a good margin, I've put an energy density of 200 Wh/kg in the Airbus frame sheet and took in consideration the battery weight computed by the frame sheet. I need 7,8 kg of these cells, which is 48 of the 12 Ah cell, in a 12S4P configuration (44,4V - 48Ah). In hover mode, I need 7 kW or 44,4V 160A or 44,4V 3,3C, and the battery efficiency is around 92%. In cruise mode, I need 1 kW or 44,4V 24A or 44,4V 0,5C, and the battery efficiency is around 96%. For the controllers or ESC, I've took the FLAM 80A from T-Motor. I've chose this one because of the voltage capacity (12S - 44,4V). Plus, this ESC is waterproof. Operations : During landing, when the SpeedQuad touch down, the drone will cut the rotors. If necessary, the rotors motors will use magnetic brake. When everything is cut, the drone will unlock the cargo bay, then emit a sound signal and display a visual signal of the state of the drone through the camera glass on each side of the drone. Then, the operators (2 operators minimum or 1 with a special kart) will come unlock the cargo bay with a mechanical key while holding the cargo bay. The drone is not able to spin any rotor without any bay. When a new bay is loaded by operators, a operator will send a radio signal to the drone. Then, the drone will lock the cargo bay, emit sound and visual signals and after a delay, will spin the rotor and take off (we can add some proximity sensor to the drone). During flight, if any problem happen, the drone will send a signal to the drone flight operator, and an embedded AI will decide to continue flight, land (vertically of horizontally) or deploy the parachute. Link : T-Motor U11 : http://www.rctigermotor.com/ht... T-Motor U12 : http://www.rctigermotor.com/ht... T-Motor FLAME 80A : http://www.rctigermotor.com/ht... KOKAM cells : http://kokam.com/cell/ T-Motor 28x9,2 Props Model : https://grabcad.com/library/t-... Prop model from GrabCAD : https://grabcad.com/library/qu... Worker man from GrabCAD : https://grabcad.com/library/wo... Tools used : Excel, XFLR5, Autodesk Fusion 360 _______________________________________________ Archives : Update 16/05 : Cruise speed, fin, cruise propeller Cruise speed : With a 10 m/s front wind, the slower you are, the more effective distance you have to do. I think a 40 m/s cruising speed is a good compromise between speed and efficiency. At 40 m/s with a front wind of 10 m/s, I need a range of 125 km with 3 kg of payload and 75 km with 5 kg of payload. The wingspan is a little smaller, wingtips are at 1,2 m from the middle, for a total 4 m effective wingspan. The wing loading is at 38 kg/m2. With higher speed, the gravity center has been moved forward at around 530 mm from the leading edge of the front wing, thus, the hover propellers are less over the wings. The L/D ratio is 14 for the frame sheet and 18 for XFLR5. The mission can be done with a L/D = 14. Fin : The fin has been moved backward and is now on top and under the fuselage to protect the propeller, the fin area is about 15% of the wings area. Cruise propeller : I've chose the T-Motor U12 with a 30 inches propeller. It have around 11 kg max trust (at 0 m/s), 3900 max RPM and 4000 N.m max torque (at 3900 RPM). T-Motor U12 : http://www.rctigermotor.com/ht... Prop model from GrabCAD : https://grabcad.com/library/qu... Worker man from GrabCAD : https://grabcad.com/library/wo... Update 07/05 : Rotors For VTOL motors, I've took the T-Motor U11, this motor can lift 7,5 kg / motor, it's waterproof and dirt resistant, that's great for the rain resistance requirement. Between the "Power Series" and "Efficiency Series", I've chose the power, because we need to hover for only 2 min, so, I think hover efficiency isn't critical. http://www.rctigermotor.com/ht... For the rotors, I was looking for a 28 inches propeller. I've took the T-Motor 28x9.2 propeller. I've found the 3d model on Grabcad. https://grabcad.com/library/t-... About, the design, little change from the initial concept, the propeller aren't on the wing tips anymore : I have less constrains, the airframe will be lighter, and the rotors less exposed. The rotors are positioned around the gravity center. Update 05/05 (2) : Wingspan increase Wingspan have been increase from 2 meters to 3 meters per wing. Slower speed, better efficiency, frame weight back to 7 kg. L/D = 16 @ 34 m/s or L/D = 18 @ 30 m/s This time, the ACDC frame sheet and XFLR5 have similar result. Update 05/05 : Speed, Rendering I have increased the distance between the two wings. I have also increase the operational cruising speed. ACDC Frame Sheet : L/D = 11,76 @ 40 m/s XFLR5 : L/D = 14,14 @ 50,5 m/s There is a big difference between the Frame Sheet and XFLR5, but in either case, I can accomplish the mission with a 5 kg frame. I have create the fuselage in the CAD software and I have some rendering! Next, I will integrate motors and propellers in the CAD model. Update 29/04 : Airfoils, XFLR5 So, I have found some airfoils : The GU25-5(11)8, the LS(1)-0417MOD, the Roncz 1145MS and the Eppler E1212MOD. The GU is used on the Quickie's canard (the front wing on a tandem wing is a big canard). This airfoil has good performance, but apparently, it has a problem : It's performance are very affected by rain. The LS1 don't have this problem and is used on the Quickie Q200. The Roncz is an improvement from the LS1 and it is use on the Long-EZ's canard, but not on any tandem wing to my knowledge. The Eppler is used on the Quickie's second wing. I will go with the LS(1)-0417MOD for the front wing and the Eppler E1212MOD for the rear wing. I'm learning to use XFLR5. For the front wing, I have put a angle of 5° near the fuselage and -1° on the wing tips. For the rear wing, I have 2° near the fuselage and -1° near the tips. I have also put winglets to reduce the wing tips vortex. The simulation run with Re from 50 000 to 2 000 000 and an angle from -3° to 12°. The CG is around at 0,45m from the front wing leading edge, 60% of the lift is made by the front wing. The wing loading is around 32kg/m2 on the front wing, or 26,7kg/m2 for an average of both wing. Result : With an angle of incidence of 2°, I have : V=34,26m/s (123km/h), CL=0,72, CD=0,044, CD/CL=16,32. With the ACDC frame sheet, I have CL=0,61, CD=0,01, CD/CL = 16,55 for 30m/s (108km/h). With the default 155Wh/kg batteries, I can take 3,2kg @ 100km and 5,4kg @ 60km. So far so good! Thing like landing gears may affect the performance, but I think I can win some weight on the fuselage. Next step : Import the wing in the CAD software. Original post (24/04) The SpeedQuad is a tandem wing aircraft drone with VTOL capacity. I was inspired by the Airbus drone design, the Rutan Quickie and the Viking Dragonfly aircraft. For my design, I'm very concerned about the stability of the drone during the vertical flight on a windy day, that’s why I am trying to design an agile, wind resistant drone. Why the tandem wing configuration? I have considered the flying wing, the tandem wing, the canard, the three surfaces and the classic configuration. With the tandem wing, the lift is distributed on the two wings. With the other configurations, at least 80% of the lift is made with one wing. For a given wing area and aspect ratio, the tandem configuration have a smaller total width. Thank to that, we have less inertia in the forward axis, thus the drone is more agile. Plus, it looks cool :) The downside of the tandem wing configuration is that the rear wing is in the wash of the front wing. That’s why we have a vertical gap between the two wings, like on the Quikie and the Dragonfly aircraft. Why a high wing loading? The wing loading of the SpeedQuad is 30 kg/m2. I am worried that with a too big wing area, the drone will be too sensitive to the wind. That’s why a have chosen to have a high wing loading, to be less sensitive to the wind. Plus, I’m taking advantage of the VTOL capacity and I’m skipping the low speed flight. I’m only considering the cruising speed, the vertical flight and a hybrid plane rotor assisted flight mode (let’s call it "rotor assist mode"). In case of emergency, we can glide to a crash zone and deploy the parachute. What’s next? I will run a CFD simulation, then, I will define the gravity center and choose an airfoil. Thanks to Airbus and Local Motors for the opportunity!
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