AA241x Spring Quarter 2015 A I R C R A F T P E R F O R M A N C E E S T I M AT I O N LECTURE 2 APRIL 1, 2015 Juan J. Alonso, Robbie Bunge, Adrien Perkins Department of Aeronautics & Astronautics Stanford University 2 Teams After a major feat of combinatorial optimization •  We have 4 teams made up •  Each team has all the necessary expertise to complete the AA241x mission •  We have (mostly) respected your wishes to be in the same team with at least one other colleague •  Minor adjustments may need to be made (due to enrollment) Please get to know your teams right away…sit together and introduce yourselves! 3 Communications (1 of 2) Class list. Go to lists.stanford.edu and subscribe to: aa241x-class Course website / wiki (want everyone to contribute!) §  http://adl.stanford.edu/groups/aa241x Piazza site: search for AA241X and add! 4 Communications (2 of 2) You will be required to create and maintain a team website that contains: §  Team members, contact information, responsibilities §  All technical details of your design, controls, mission planning (it is up to you how you want to organize it…but it must be kept current: we will check it regularly to gauge progress) §  Problem set solutions §  Relevant data §  Pictures, videos, etc. documenting work §  Come up with a Team Name by next Monday! §  Send me your team name so I can create an account for each team to be able to edit the wiki §  Come up with a POC / Chief Engineer 5 Hardware Hardware for each team will be handed out at the end of lecture: §  It is your responsibility to use it properly! §  Wait until you know how to use it before frying it! §  Adrien will give you more details…hang on… §  You will get a Bixler 2 as well…we are waiting for the brand new kits (backordered and being shipped from Hong Kong), but these ones can get you up in the air as soon as this weekend §  Hardware “training/tutorial” session on Friday. More details at end of lecture 6 Safety First For you to have access to Durand 353 / 464, you must have completed safety training: §  Each team will be handed a code for Durand 353 §  Every team member must have completed EHS-4200 training (verified by showing Prof. Alonso a copy of your AXESS page stating so) before a code is handed out to a team §  If you have not completed this training already, you can go to AXESS, click on “Stars”, find EHS-4200, and complete the course online §  This is important! Pay attention to it! §  Separate safety training will be provided for use of the laser cutter 7 First Flights Saturday morning, if you are interested, a bunch of us will be out there helping any team that needs it get up in the air 10 am target time…discuss! This Year’s Mission 8 2015 Mission: Fire Monitoring and Prevention •  This year’s mission is inspired by UAVs that may: §  Monitor a forest fire as it spreads §  Extinguish a fire using an on-board load of water •  Your objective is to analyze, design, build, and test fly an unmanned aircraft that most successfully monitors and extinguishes a fire §  It is a competition! §  Many choices to make §  Work includes vehicle, control system, mission, operation, construction, etc. §  Not for the faint hearted! 2015 Mission: Fire Monitoring and Prevention Valid fire region Cell with active fire Prevailing wind Camera Field of View (FOV) = f(h) Extinguished cell 2015 Mission: Parameters (Near Final…) •  •  •  •  •  •  •  •  •  •  •  •  •  •  FIELD_CENTER_LAT = 37.4224444° FIELD_CENTER_LON = -122.1760917° FIELD_RADIUS = 340 m CELL_SIZE = 20 m Aircraft cannot exit Lake Lagunita area (defined as a circle of D = 340 m, centered on (LAT,LON) Number of available “squirts” is proportional to additional mass carried, Nsquirt / mwater = 1 “squirt” / 10 grams Can only squirt when flying > 100 ft and < 400 ft altitude Once a cell has been squirted it cannot catch fire again Mission duration specified, Tmission = 10 min Battery capacity unlimited, but must land when voltage is lower than a pre-specified threshold Prevailing wind direction is given Stochastic fire propagation algorithm known Nstart<= 2 fires can start at t = 0 sec Fire evolves with Δt = 15 sec 2015 Mission: Scoring •  Mission score is related to your ability to prevent the fire from spreading, compared to allowing the fire to propagate unattended •  Cells burned if fire unattended, Nburn-unatt •  Cells burned with UAV active, Nburn-UAV •  Mission score = 100 x (1 –(Nburn-UAV / Nburn-unatt)) •  Reliability multiplier δrely = 1 + 0.1 floor (nflight/5) •  Allowed 3 “mulligans” during official flights 2015 Mission: Competition •  AA241x final competition will take place over multiple days (June 1-9, 2015). •  On 3rd or 4th day, we invite guests from AA and other departments / institutions •  Final reports due on June 10, 2015 •  Final class party that week 14 Performance Estimation: Why Do I Care? •  Assessment of flight path, climb capability, ability to carry weight, turning radius, flight speed, endurance, etc, is critical for the success of your vehicle •  Performance estimation is a critical aspect of this work •  Stability & Control: •  Inform control effort development •  Guarantee stability (and control capability) in all segments of your mission •  Finally, you need to have performance models to guide the choices that you will make in your mission strategy 15 How might you use performance models? •  Initial simple 2D simulations: turning radius, speed capability, weight-carrying capabilities •  More detailed 3D simulations: climb / descent, altitude hold, etc, etc. •  Stability and control derivatives and characteristics 16 What is this all about? •  Frankly, it is F=ma for all static conditions •  A simplified list: •  Lift capabilities / CLmax / Stall •  L/D (vs CL, vs airspeed) for performance optimization •  Max speed capability / power draw •  Drag polars (performance in all mission segments) •  Climb / glide capability •  Stability and control derivatives •  Longitudinal stability •  Endurance •  Even aircraft modes of oscillation 17 Some Examples •  Taken from PS responses from one of the teams in last year’s AA241x •  Can serve as inspiration (see web page) of things you might want to do in your own work •  Team Name: Dronin 47 18 Mass and Inertia Estimation •  The “m” in “F=ma” •  Someone in your team must be responsible for maintaining (*and updating!) a weight / inertia statement. This feeds into everything else! 19 Aerodynamic Model •  It will be helpful to create a full aerodynamic model •  Begin with a geometry description, the aerodynamic properties of the airfoil sections, and a vortex lattice model 20 Aerodynamic Model (2) •  Lift / drag performance 21 Stability (and control!) derivatives •  Vortex lattice methods and give you a lot of information 22 Stability (and control!) derivatives •  Vortex lattice methods and give you a lot of information. Damping / frequencies are critical Thanks a lot for your attention! Questions & Answers More details at http://adl.stanford.edu/groups/aa241x