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Home , Ingenuity (helicopter)

NASA Aeronautics Contributions to Ingenuity Speakers (in order of presentation): Larry Young1 Michelle Dominguez1 Brian Allan2 Carlos Malpica1

1NASA 2NASA

March 23, 2021

Moderated by Jeffrey McCandless

The Mars Helicopter team is composed of JPL, NASA Ames, NASA Langley, and AeroVironment representatives. Ames and Langley support is provided by the Aeronautics Research Mission Directorate (ARMD) Revolutionary Vertical Technology (RVLT) project.

1 Historical Context

• Majority of previously proposed aerial vehicles for Mars exploration have been “Mars airplanes”

• However, many other vehicle types have been proposed for Mars, as well

• Mars have been proposed since the mid- to-late 1990’s; Ames efforts began in 1997 with a Center Discretionary Fund effort

2 “First” Planetary Aerial Vehicles

Soviet Union’s Vega I and II missions successfully flew two small pressurized balloons at an altitude of ~54 km in the atmosphere of in 1985 Source: http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1984-128F 3 Partial Survey of Mars Airplane Concepts

10000 • Reed (1978) Electric Propulsion

• Butts and French (1979) 9000 Hydrazine Reciprocating Engine Propulsion • Clarke, et al (1979) 8000 Rocket Propulsion • Neunteufel (1979) 7000

• French (1986) 6000

• Sivier and Lembeck (1988) 5000

• Colozza (1990) 4000 Range (km) Range • Raymer, et al (1992) 3000

• Hall, et al (1997) 2000 In general, • Malin, et al (1998) 1000 decreasing Estimated Maximum(km) Estimated Range • Calvin, et al (2000) 0 with time • Smith, et al (2000) 0 100 200 300 400 Vehicle Total Mass (kg) • Guynn, et al (2003)

Source: Young, L.A. et al, “Aerial Explorers,” AIAA-2005-912 4 Arguably the Most Influential “Mars Airplane” Concept of All

Reed’s (DFRC) “Mini-Sniffer” (with hydrazine mono-propellant reciprocating engine) Source: http://www.dfrc.nasa.gov/gallery/photo/Mini-Sniffer/Large/index.html 5 More Mars Airplane Proposals

AME (1996) MAGE (1998)

“Canyon Flyer” (2000) ARES (2005) Sources: AME: http://www.nasa.gov/centers/ames/research/technology-onepagers/mars-airplane.html MAGE: http://www.msss.com/mage_release/index.html “Canyon Flyer:” Smith, S.C., et al, AIAA 2000-0514 ARES: https://ntrs.nasa.gov/api/citations/20050170955/downloads/20050170955.pdf?attachment=true6 Levine, J., LPI 1258, 2005 Mars Rotorcraft Studies From 1997 to Present

7 Focus on Critical Technologies

CFD Image Source: Corfeld, et al, AIAA-2002-2815

8 LY

Six Years Ago…

• Approximately six years ago (circa 2014) JPL proposed a small Mars helicopter that could act as an aerial scout for the large Rover being developed for the 2020 Mars mission

• Since the early beginning, JPL has worked with NASA Ames and NASA Langley Research Centers to develop such a vehicle

• This Ames/Langley work was sponsored by the ARMD Revolutionary Vertical Lift Technology (RVLT) project

9 MD “Kick-off” Meeting at Ames Between JPL, NASA Ames and Langley, and RVLT project

10 MD General Description of Ingenuity Mars Helicopter

Mass ~1.8 kilograms Configuration 2-Bladed; Coaxial Rotor Diameter 1.2 meters Powerplant solar-electric propulsion with batteries storing energy; solar cells on little beanie cap above rotors Recharge Time 1-2 Martian days (“Sols”)

11 MD Ingenuity

12 MD Victoria Crater With a helicopter, the same scouting 340 Sols Scouting NW Rim Imaging to Find Ingress Point could be Mapping Stratigraphy done in a small number sorties

13 9/18/14 Golombek: Mars Heli-Scout Aeronautics Tasks in Support of Ingenuity: Aeroperformance

• Rotor design- and peer-review support • Airfoil characteristics 2D CFD modeling • Comprehensive rotorcraft analysis performance modeling for hover and forward flight • Solar array aero interaction and sizing analysis in hover • In-parallel inhouse “first ever” surrogate Mars rotor edgewise forward flight testing in the Mars wind tunnel in Ames N242 large low-pressure chamber; correlation of experimental results with CFD predictions

14 MD Surrogate Rotor Forward-Flight Under Mars-like Conditions

15 MD Aeronautics Tasks: Facility Aero Interference Effects

• Analytical and mid-fidelity CFD (RotCFD code) study of flow recirculation of rotor systems in JPL 25-ft Space Simulator and other NASA large vacuum chambers • Experimental study of flow recirculation of rotor systems in JPL 25-ft Space Simulator (aka “Weather Test") • Development of a time-dependent analytical (tuned with mid-fidelity CFD results) ”wind” model to incorporate in JPL Heli-CAT Mars Helicopter simulation for simulation of vehicle hover behavior in Space Simulator with flow recirculation 16 MD Experimental Evaluation of Rotor Flow Recirculation and Interference Effects in JPL 25-ft Space Simulator

17 MD Aeronautics Tasks: Facility Development Efforts Conceptualization, development support, and mid- fidelity CFD (RotCFD) analysis of… • “swinging arm” approach for simulating vehicle hover response to winds • alternate approaches to forward flight performance and Sys-ID testing – custom wind tunnel designs – Langley TDT “idle” and “coast down from idle” wind tunnel testing – “rotating arm” enhancements to earlier “swinging arm” test stand

– JPL/Caltech fan array (aka “Wind Wall”) 18 MD Aeronautics Tasks: Higher- Fidelity CFD Contributions

• Overflow predictions of compressible low-Reynolds number airfoil characteristics • Overflow hover performance comparisons with and without solar array and fuselage “cube” • Overflow forward flight performance with and without solar array and “cube” 19 BA Mars Helicopter Airfoil CFD Results

• Martian atmosphere has an atmospheric density that is approximately 1% of the at • This results in very low Reynolds numbers on the rotor – Chord Reynolds numbers vary between 103 and 1.7x104 • Hover tip Mach numbers up to 0.76

Reference: Koning, W. J. F., Johnson, W., and Allan, B. G., “Generation of Mars Model for Comprehensive Analyses,” 20 American Helicopter Society Technical Meeting on Aeromechanics Design for Vertical Lift, San Francisco, CA, Jan. 16–18, 2018. Mars Helicopter Airfoil CFD Results

• Very little airfoil data exists at these conditions • Testing capabilities at these conditions are difficult and would take too much time to acquire test data to meet schedule • CFD was used to generate airfoil data for the rotor comprehensive design and analysis code, CAMRADII – Airfoil pitch sweeps from -15 to 20 – sweep from 0.1 to 0.9 – Reynolds numbers between 103 and 1.7x104

21 Incorporating Airfoil Results into CAMRAD

• Simulations were performed using the OVERFLOW flow solver developed at NASA – Compressible RANS flow solver • Structured overset mesh topology • Mars atmospheric conditions • Koning et al. [2019] showed good agreement to rotor performance test from CAMRADII predictions using airfoil CFD calculations using OVERFLOW with transition model • While hover performance predictions are good, there is still much we don’t know about the flow physics at these conditions – Need for airfoil wind tunnel test data for code validation and design and testing of next generation Mars rotor airfoils

Ref: Koning et al. [2018]

Ref: Koning et al. [2018]

22 Reference: Koning, W. J. F., Johnson, W., and Grip, H. F, “Improved Mars Helicopter Aerodynamic Rotor Model for Comprehensive Analyses,” AIAA Journal, Vol. 57, No. 9, 2019, pp. 3969-3979. Mars Helicopter 3D CFD Simulations

• During the design there was concern about the solar panel aerodynamic loads especially in forward flight – Wake from panel effecting rotor performance and aerodynamic forces and moments from the panel • Design tools were not able to accurately model the aerodynamic interference between the rotor and solar panel • CFD simulations of the Mars Helicopter with body and solar panel were able to provide the design team with higher-fidelity predictions of the aerodynamic interactions – Aeroloads on solar panel and body in the presence in of rotor – Effects of solar panel wake on rotor performance

23 Numerical Approach

• CFD simulations were performed using OVERFLOW, a compressible Navier- Stokes flow solver developed at NASA • High order scheme on convective terms (6th-order) – reducing diffusion and dispersion errors • 2nd order time accuracy using dual sub-iterations • Loose-coupling between CFD and comprehensive rotor analysis code (CAMRADII) to perform rotor trim • Structured overset mesh topology Surface Grids for Mars Helicopter Side View • 98 overset grids (28 grids for the rotor, solar panel, and body) • 84.8 million total grid points (16.8 million body) • NAS HECC facility Top View • 2-3 days runtime per simulation using 600 Intel Ivy-Bridge cores – 6.5 hours per rotor revolution – typically, 7-10 revolutions needed 24 Higher-Fidelity CFD Hover Results

25 Hover Performance

• CFD hover calculations showed little effect of the solar panel on the Figure of Merit (FM) hover performance – FM is the ratio of ideal rotor torque to the actual torque • Comparison to hover performance test data show good agreement

26 Forward Flight CFD Results

27 Mars Helicopter in Forward Flight

• CFD simulations at 10 m/s forward flight • Trade study on the solar panel was performed • CFD predictions showed little difference between the extended and originally designed solar panels on the rotor performance in forward flight • Simulations did show that extending the solar panel length did increased mean and unsteady pitching moments – The design team determined that these increases were within acceptable ranges

28 Aeronautics Tasks: Sys-ID Analysis and Flight Control Efforts

• Sys-ID analysis/support of hover characteristics using ‘swing arm’ for full-scale prototype and engineering development model (EDM-1)

• Sys-ID forward flight testing using JPL/Caltech ducted-fan array, aka ‘wind wall,’ of EDM-1 and the flight model (FM), aka Ingenuity

• Aeronautics support of Sys-ID work continued all the way to completion of FM testing by January 2019 29 CM Demonstration of Lift

30 CM Full-sized Rotor Mars Helicopter Prototype Safety tether (removed for free-flight) Visual targets for motion tracking

Counter-rotating rotors

Motor, gears & pitch linkage assembly

Electrical cables Landing legs

31 CM 1.21 meter diameter rotors Path to Controlled Free Flight

Modeling and ˙ = (, , ) simulation

System identification

Attitude Control Free flight32 CM Sys-ID Program

Control derivatives Fixed & actuator dynamics

Translational Robotic stability arm derivatives

Rotational stability Gimbal derivatives & apparent inertia Free flight 33 CM Free Flight

Free Flight Demonstration May 31, 2016

34 CM Mars Flight Simulation

35 Operational Status

Mars 2020 launched on July 30, 2020.

Landing occurred on February 18, 2021.

The Ingenuity helicopter may have up to five flights over a 30- test window.

36 CM Ingenuity Mars Helicopter Development Team includes • NASA JPL – MiMi Aung, Bob Balaram, Havard Grip, Daniel Scharf, Joe Melko, Amiee Quon, Teddy Tzanetos… • NASA Ames (in addition to today’s presenters) – William Warmbrodt, Wayne Johnson, Alan Wadcock, Natasha Schatzman, Geoffrey Ament, Eduardo Solis, Witold Koning, Haley Cummings, Natalia Perez-Perez, Shannah Withrow- Maser, Farid Haddad, J. Ken Smith… • NASA Langley (in addition to today’s presenter) – Susan Gorton (Revolutionary Vertical Lift Technology), Norm Schaeffler… • AeroVironment – Ben Pipenberg, Matt Keennon, Chris Bang… 37 CM Acknowledgments

A huge “thank you” for enabling this seminar goes to all of the supporting parties, including the Public Affairs Office (PAO) representatives from Ames and Headquarters.

We appreciate the logistical coordination from the NASA Aeronautics Research Institute (NARI), particularly Rajan Shankara and Michael Tsairides.

38 More Information

NASA publications https://sti.nasa.gov

Mars 2020 https://mars.nasa.gov/mars2020

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