preliminary design of a small unmanned battery powered tailsitter.

1.
The application prospect of battery-driven tailgate.
Tailstock with vertical takeoff and landing capability (VTOL)
, Hover like a helicopter, transition between vertical and horizontal flight, and efficient wing-
Fly as a fixed wing aircraft.
Designed for reconnaissance, surveillance, delivery and rescue, the tailgate can take off vertically from enclosed environments such as woodlands, small islands, streets, disaster sites, and even mobile platforms on vehicles and ships.
Project Wing 【1]
The goal of Google X is to develop tailors for fast package delivery in various situations, such as delivering vibrators to rural heart patients;
Research on innovation of small enterprises (SBIR)plan (2012)
S. Air Force aims to have the rear seat of the channel fan power with long endurance.
By battery and Brushless DC (BLDC)
The car, small driverless tailstock has the advantages of light weight, low cost, easy use and maintenance, low vibration and noise.
More importantly, the battery-driven tailgate can take off from the surface of Mars and Titan without the help of any runway or launch equipment, and then conduct a remote exploration, hover over the target point, or direct landing for detailed testing.
Surrey Space Center2]
NASA Ames Research Center3, 4]
For better mobility and mission performance in the exploration of Mars, studies have been conducted on such probes.
Review of design methods.
There are many existing configurations of the battery-powered tailstock, such as the Mars tailstock [2]
T-developed by the University of Surrey-wing [5]and Bidule [6]
Developed by the University of Sydney, ITU-Tailsitter [7]
Developed by SkyEyeV [University of Technology], Japan8], the ATOMS [9]
By Delft University of Technology and Quadshot, Netherlands [10]
Developed by transition robots.
Of these vehicles, only T-
Wing, Surrey Mars tailsitter, ITU
Tailsitter is available through public literature.
In the development of T-engines, both motors and reciprocating engines have been used
Wing drone (UAV)
The battery-driven propulsion system is used in the early verification phase [5]. The T-
Rumor of wing layout and multi-disciplinary research optimization of double propellers based on detailed subsystems, aerodynamics-
Advance the integrated model, the weight structure model and the control model.
This method is effective for the design of battery-driven tailors with different tasks and constraints without statistical guidance [11].
Too many parameters and constraints should be considered, however, with at least 13 equation constraints, 36 Actual design variables, and 75 fixed design parameters.
At the same time, the feasibility of the design space and the impact of key parameters such as the ratio of battery weight to takeoff weight (battery ratio)
The performance of the aircraft has not been discussed.
A more general tailgate configuration with a double rotor needs to be studied.
The Mars tailor in Surrey is an adaptation of the land eye of QinetiQ-
This is a double rotor design of \"helicopter assembly [2].
To this end, 12 different key subsystems are designed in detail according to the task architecture and system requirements. High-
The horizontal balance of mass and power proves the feasibility of tailsitter.
This design approach illustrates this well, and engineers are more likely to implement it, and if integrated optimization is implemented, the range and endurance of the tailstock can be improved. The ITU-
Tailsitter uses a hybrid
Dual propulsion system [7]
, Driven by a large diameter folding propeller located in the aircraft nose and a small diameter pipe fan system located at the tail of the aircraft.
The former is used for hover, vertical takeoff, vertical landing and low speed transition stages, and the latter for horizontal and high speed flight stages.
This is a new attempt to address the efficiency of the tail fiber, although some deadweight is introduced at each stage.
Variables such as maximum takeoff weight, wing load, and battery weight are optimized for maximum payload and cruise duration.
This method can be applied in the case of selecting the propulsion propeller and the culvert fan.
Generally speaking, in the preliminary design, the thrust function of the propeller diameter and the propeller speed n and the wind speed v is not equal to T = T (n, v)
Already confirmed.
Therefore, the optimization design can not proceed smoothly.
About the tailor.
The battery-driven tailgate simplified aerodynamic configuration consists of four main parts, as shown in Figure 1, the fuselage, straight rectangular wing, double reverse propeller, and the double eleven at the rear edge.
Batteries, payload, avionics and other necessary instruments can be installed in the fuselage and wings.
In order to make full use of the sliding flow of the propeller to obtain sufficient control torque, attention should be paid to the low speed vertical flight performance of the propeller, the radius of the propeller is [R. sub. p][
About equal to][b. sub. wing]
4/recommended.
For different flight modes, including low-speed but high-thrust vertical flight mode and high-speed but low-thrust horizontal flight mode, a variable-pitch propeller is proposed.
Same as Bidule [6]
, Rolling with Double Eleven
Attitude and field
Attitude control, while using the rotation speed and collective spacing of this double propeller to provide height and swing
Attitude control, respectively.
The flight experiment of Bidule verified the stability and energy control of this configuration, which is no longer discussed here.
This paper will focus on weight, power, energy consumption and endurance performance.
Figure 2 depicts the task outline of a tailor with a dotted line.
The tailgate climbs vertically from the takeoff point until it reaches the mission level and then transitions to a horizontal flight (V2H);
After completing the flight task, the tail nanny will move to the target landing area and transition to a vertical drop (H2V)
Until landing.
Compared with regular takeoff and landing (CTOL)
As shown in Figure 2, there is no lateral acceleration or deceleration in the aircraft\'s mission profile.
Each transition on the tail flight path is reduced to a right angle with the preliminary design.
However, in further studies, an optimized curve transition path should be introduced for actual flight.
Objectives and paper structure.
This paper aims to provide a feasible solution for the preliminary design of the small battery-driven tailstock, providing effective guidance for further detailed design and vehicle realization of weight, geometry, power and energy consumption.
As shown in Figure 2, a small battery-powered tail rack will take advantage of current technology to complete a flight mission at a height of 1000 m.
The allowable mass of the tail frame is 10 kg, and the mass of the payload is 1. 0 kg.
Maximum horizontal flight duration will be estimated and the corresponding optimal wing load and battery ratio will be recommended by optimization.
In the second section, the three subsystems of takeoff weight, power level and energy consumption and battery discharge will be modeled.
In section 3, the influence of wing load and battery ratio will be analyzed and a feasible design space for the small battery-driven tailstock will be given.
The fourth section will explain the preliminary design method and conduct a design case study to verify it. 2.
Subsystem model 2. 1. Takeoff Weight.
Electric rotation-wing platform [12]
, Take-off weight of unmanned battery-driven tailsitter [W. sub. TO]
It consists of four main components: fuselage, BEMP propulsion system, avionics and payload.
The BEMP system is controlled by battery and electronic speed (ESCs)
Motor and propeller :[
Mathematical expressions that cannot be reproduced in ASCII](1)where [W. sub. fu-str]
Represents the combined weight of the fuselage, joint structure and other structures except the wing, [W. sub. EMP]
Indicates the combined weight of ESC, motor and propeller and [W. sub. PL]
Represents the weight of the payload.
Wing weight]W. sub. wing]
Battery weight [W. sub. B]
It is listed separately for discussion as they are more important for aircraft endurance and account for the main proportion of takeoff weight.
Continuous weight ratio can be defined :[k. sub. F]= [W. sub. fu-str]/[W. sub. TO], [k. sub. A]= [W. sub. avionics]/[W. sub. TO]
Battery ratio [k. sub. B]= [W. sub. B]/[W. sub. TO].
Wing weight can be indicated [W. sub. wing]= [k. sub. W]
S, S is the wing area and [k. sub. W]
Does N/[indicate the wing weight coefficient of the wing unit area weight? m. sup. 2].
The weight of the wing can also be indicated [W. sub. TO]: [W. sub. wing]= [[k. sub. W]/[W. sub. TO]/S][W. sub. TO]= [[k. sub. W]/[k. sub. WS]][W. sub. TO], (2)where [k. sub. WS]= [W. sub. TO]
/S represents the wing load of the tail frame in N/[m. sup. 2]. And then (1)
Can be reduced [W. sub. TO]= [W. sub. EMP]+ ([k. sub. W]/[k. sub. WS]+ [k. sub. B]+ [k. sub. F]+ [k. sub. A])[W. sub. TO]+ [W. sub. PL]. (3)Solving (3)
The takeoff weight is [W. sub. TO]= [W. sub. EMP]+ [W. sub. PL]/1 -[k. sub. B]-[k. sub. A]-[k. sub. F]-[k. sub. W]/[k. sub. WS], (4)
Where is the payload weight 【W. sub. PL]
Will be given by the mission; [W. sub. EMP]
The maximum operating power of the vertical climb stage shall be determined.
Can be from (4)
The takeoff weight will follow 【k. sub. WS]decreases or [k. sub. B]
When [an increase in a given payload]k. sub. B]+ [k. sub. W]/[k. sub. WS]< t -[k. sub. A]-[k. sub. F]
Still very satisfied. 2. 2.
Power and Energy.
In order to achieve vertical takeoff and landing, the thrust-weight ratio [for the tail frame [K. sub. T]
Need to be greater than 1.
The maximum design thrust of the tail seat can be written [T. sub. max]= [K. sub. T][W. sub. TO]. (5)Stone [11]
It is recommended that the maximum thrust need 1.
Used to handle non-ideal situations and transition maneuvers, 15 times or more larger than takeoff weight.
Then the value [K. sub. T]= 1.
This paper presents a tailgate for small battery drive.
The power required by the propeller provides the thrust T for the aircraft, which can be calculated by momentum theory [13][
Mathematical expressions that cannot be reproduced in ASCII](6)where A = [pi][R. sup. 2. sub. P]
The area of the propeller disc;
V is the axial forward speed of the propeller;
Induced power factor [kappa]
Have typical values in [range]1. 15, 1. 25]
Conservative value [kappa]= 1. Suggestion 2.
Although the momentum analysis cannot give accurate power calculation results, it takes into account the efficiency of the propeller for thrust and wind speed, and provides an effective solution for the preliminary design, no detailed parameters of the propeller are required. 2. 2. 1.
Speed up the climb.
Under the action of the force of the vertical take-off and climb speed, it will gradually push from zero propeller thrust T (0 < T < [T. sub. max]).
Achieved the desired climbing speed [V. sub. C](0 < [V. sub. C]< [V. sub. max])
The tailgate will climb the task height at a constant speed.
Assume that acceleration is done by the maximum thrust allowed [T. sub. max]
The tail seat reaches the height H (t)
Climbing Speed is V (t)at time t. Ignoring wing-
The forces acting on the plane include the gravity of the wing, the thrust of the propeller, and the pneumatic resistance.
Newton\'s second law can be derived ,[
Mathematical expressions that cannot be reproduced in ASCII](7)
Where n is the Peukert coefficient; [P. sub. LF]
Represents the maximum range of power [P. sub. R]
Or maximum battery life [P. sub. E].
Considering the efficiency of energy conversion, the horizontal flight life is [
Mathematical expressions that cannot be reproduced in ASCII](31)where [m. sub. B]= [k. sub. B][W. sub. TO]
/G is the quality of the battery and [K. sub. BEm]
Is the specific energy of the battery. 3.
The parameter influence study of conventional battery-driven aircraft, the power required for horizontal flight is [[bar. P]. sub. LF]= [C. sub. D]/[C. sup. 3/2. sub. L][Square root ()2/[rho])][Square root ()[W. sup. 3. sub. TO]/S)]. (32)
It is generally believed that the efficiency of the propeller is constant [[eta]. sub. P]
Has nothing to do with flight conditions;
Total efficiency of BEMP propulsion system [[eta]. sub. tot]= [[eta]. sub. B][[eta]. sub. E][[eta]. sub. M][[eta]. sub. P]
It can be used to evaluate the impact of wing load and battery ratio on endurance performance, such [
Mathematical expressions that cannot be reproduced in ASCII](33)
Can be from (33)
There is a positive correlation between endurance and battery ratio, and there is a negative correlation between endurance and wing load.
Simulation was performed to investigate the effect of wing load and battery ratio on the range and endurance of the battery-driven tailstock. 3. 1. Parameters.
At the beginning of numerical analysis, three different categories need to be distinguished: constant or assumed constant parameters, front parameters and constraints between design variables and intermediate variables. (1)
Constant or assumed constant parameters are listed in Table 1, which are associated with the design experience of the tailor [2]
General level of existing technologies for wing structure [18], lithium-polymer (Li-Po)
Battery, electric tuning, DC brushless motor 【19]
Typical mission performance of small battery-powered unmanned aerial vehicles [20, 21], and so forth. (2)
Wing load is a design variable [k. sub. WS]
Battery weight ratio [k. sub. B].
It is famous (4)that [k. sub. WS]> [k. sub. W]/(1 -[k. sub. A]-[k. sub. F])= [k. sup. 0. sub. WS]and [k. sub. B]< 1 -[k. sub. A]-[k. sub. F]-[k. sub. W]/[k. sub. WS]= [k. sup. 0. sub. B].
Analysis will focus on \"small tail goods]W. sub. TO]< 20 kg;
Therefore, the numerical approximation [k. sub. WS][
Greater than or equal to]2[k. sup. 0. sub. WS]and [k. sub. B][
Less than or equal to]0. 9[k. sup. 0. sub. B]
Will be applied. (3)
Intermediate variables include climbing speed [V. sub. C]
And the quality of the motor.
Propeller system]m. sub. EMP]
, The power and energy consumption that needs to be optimized, rising and falling ,[P. sub. C], [E. sub. C], [P. sub. Des], and [E. sub. Des]
Evaluation is required. 3. 2.
Simulation results (1)
The design space is feasible.
As can be seen from Figure 4, the left and right margins of figure 4 are consistent (a)and 4(b)
Between the two, the feasible design space for the battery-driven tail rack with respect to wing load and battery ratio is shown.
The left distance represents the smallest [k. sub. B]for different [k. sub. WS]
This means that the battery carried can only support the tail seat to climb up the task height vertically and then land on the ground. There are [t. sub. LF]
= 0, the allowed quality of the tail frame is set to 3 [
Less than or equal to][m. sub. TO][
Less than or equal to]20 kg.
Other parameters are consistent with the previous simulation listed in Table 1.
Figure 8 shows the maximum level of flight endurance for different Mission Heights and allowed takeoff weights.
For the same mission height, the level of flight endurance increases when a larger takeoff weight is allowed.
But this growth will slow down, especially in [m. sub. TO]> 10 kg.
The maximum level of flight life of the 10 kg battery-powered tailsitter is about 2.
The mission height is 792 long and 250 hours long.
The lower mission height contributes to a longer level of flight endurance expected to take off weight.
When the mission height drops from 1000 to 250, it is about 0.
Allow an extension of 7 hours with a quality of more than 10 kg.
This is not obvious for small battery-powered tailseats weighing less than 5 kg.
Accordingly, Figures 9 and 10 show that the best value for wing load and battery ratio decreases as the mission height drops, while for small tailors like [this] is not clearm. sub. TO]< 5 kg.
For the same mission height, Figure 9 and Figure 10 show that higher battery ratios and smaller wing loads are necessary in order to obtain the best level of flight endurance with the increase in the allowed takeoff weight.
It is not difficult to inference (4)that [k. sub. B]+ [k. sub. W]/[k. sub. WS]= 1 -[k. sub. A]-[k. sub. F]-([W. sub. M]+ [W. sub. PL])/[W. sub. TO], so greater [W. sub. TO]
Means the feasible scope [k. sub. B]and [k. sub. WS]extend.
As shown in figure 4, higher battery ratios and smaller wing loads help improve flight performance and (33).
In order to verify the rationality of the design results, the design parameters and performance features of four battery-powered ground drones are collected, as shown in Table 2, where the electrical T-wing [22](E-T-wing for short)and ITU-Tailsitter [7]
Is the tailsitter configuration; TURAC [21]
Configuration of independent propulsion systems for vertical and horizontal flight, respectively; ITU-Tailless [20]
It is a CTOL drone with flying wing configuration. The E-T-
The wing demo car is driven by nine. 1 kg Ni-
Cd battery with a specific energy of 110 J/g, about 396 Wh/kg.
In addition to the unreliable problems caused by the motor speed controller [5]
, There may be other problems resulting in the cancellation of the power plan.
These problems may cause the aircraft to take off too much weight, the wing load is too large, and the diameter is small (less than 0. 6 m)
A propeller that leads to inefficient propulsion.
High-power operation, 3.
Hover 138 KW and 1.
021 KW for horizontal flight, not only will the battery discharge duration be shortened, but also high current consumption [leading to a decrease in the effective capacity of the battery]15]. Both ITU-
Tailsitter and TURAC adopt separation
The dual propulsion system, the independent propulsion system for vertical takeoff and landing, inevitably introduces self-weight for horizontal flight. As (33)
The heavy wing loads listed in Table 2 do not help improve endurance performance. CTOL ITU-
Tailless is listed for comparison. Hand-
The launch can reduce the take-off energy consumption, and the aspect ratio wing can achieve better aerodynamic performance, so the horizontal flight duration is much longer. Carrying 1.
The 0 kg payload, the 10 kg-inch unmanned battery-driven tailsitter optimized for design has a level 2 flight life capability.
18 hours at a mission height of 1000 m, ITU\'s comparative performanceTailsitter.
At the same time, figures 9 and 10 show the corresponding optimal wing load and battery ratio [k. sub. WS]= 108. 2 N/[m. sup. 2]and [k. sub. B]= 0.
4152 respectively.
The energy consumption of avionics and other instruments needs to be counted in further studies in order to estimate battery life more accurately. 5.
Summary and conclusion for the horizontal flight performance, the design process of the battery-driven tailgate is simplified.
A complete flight model of a small unmanned tailgate aircraft is established, and it is discussed in detail in stages, which provides a basic reference for the flight path optimization of tailgate aircraft.
The feasible design space and illustrated design methods, as well as the power level and energy consumption at each flight stage, can be used to provide guidance for the detailed design of the tailor.
Although the design method was originally designed for ground drones, this can also be applied to Mars tailors, taking into account environmental parameters and flight tasks.
Competitive interest authors state that there is no competitive interest in publishing this paper.
Thanks to the author for the support provided by the China Aviation Science Foundation under grant no. 20145788006.
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Wang Bo, Hou Zhongxi, Liu Zhaowei, Chen Qingyang, Xiong Fengzhu, College of Aerospace Science and Technology, National University of Defense Technology, Changsha 410073, China Communications should go to Hou Zhongxi;
Nudtxiaowang @ 163.
Received on November 8, 2015;
Revised in April 4, 2016;
Accepted by academic editor of April 17, 2016: Paolo tortortora description: Figure 1: Schematic diagram of a small unmanned battery-powered tailsitter.
Description: Figure 2: comparison of the mission profile of the CTOL aircraft and the tailgate aircraft.
Description: Figure 3: Illustration of the battery discharge process drawn with variable current.
Description: Figure 4: feasible design space for wing load and battery ratio.
Description: Figure 5 :(a)
Takeoff weight of all possible designs; (b)
Optimal constant climb speed and motor
Propeller system weight for different wing loads.
Description: Figure 6: Comparison of Power levels between climbing and maximum endurance level flight.
Description: Figure 7: flow chart of preliminary design of the battery-driven tailgate.
Description: Figure 8: maximum endurance for different Mission Heights and takeoff weights.
Description: Figure 9: optimal wing load for different Mission Heights and takeoff weights.
Description: Figure 10: Optimal battery ratio for different Mission Heights and takeoff weights.