This presentation is to discuss the Armstron airworthiness process and the work required to clear to GO1 Inert Test Article for captive carry flights

Asher, Troy

Bui, Trong

Butler, Brad

Mcwherter, Shaun

Miller, Chris R.

Miller, Eric J.

Moseley, David

Piplica, AJ

Spivey, Natalie D.

NASA Technical Reports Server

Captive-Carry Flight Demonstration of an Inert Test 
Rocket Using a Business Jet as an Air Launch 
Platform
June 27, 2018
06/27/18 1
Eric J. Miller1, Chris R. Miller1, David Moseley1, Natalie Spivey1, Trong Bui1, Shaun Mcwherter1, 
Troy Asher1, Brad Butler1, AJ Piplica2
1NASA-Armstrong Flight Research Center, Edwards, California; 2Generation Orbit Launch 
Services, Inc., Atlanta Georgia
https://ntrs.nasa.gov/search.jsp?R=20180004443 2019-08-31T15:28:00+00:00Z
Agenda
• Purpose: discuss the Armstrong airworthiness process and the work required to 
clear the GO1 Inert Test Article for captive carry flights
• Historical Perspective
• Generation Orbit Overview
• Project Objectives
• AFRC Airworthiness Process
• Project Timeline
• C-20 and ITA Description
• UAVSAR vs ITA
• Flight Test Plan 
• Discipline Analysis
• Instrumentation and Data Displays 
• Ground Testing 
• Flight Testing
• Conclusions and Project Challenges
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Historical Perspective
• Past NASA Air Launch Projects:
– X-15
– F-104 Air-Launched Sounding Rocket 
– Lifting Body Research
– B-52/Pegasus air launches
– X-37/X-40
– X-43 Hypersonic Research 
Kelly, J., et al. "Motivation for Air-Launch: Past, 
Present, and Future", AIAA SPACE and 
Astronautics Forum and Exposition, AIAA SPACE 
Forum.
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GO1-Rocket Vehicle 
• GOLauncher 1 (GO1) is a high-speed 
flight testbed for research and 
development of hypersonic systems
• Capable of reaching speeds up to 
Mach 7 with a test payload attached
• GO1 development is supported by 
key partnerships at NASA and the 
US Air Force
• Operated from Cecil Spaceport in 
Jacksonville, FL under FAA/AST 
launch license
• Flight is planned for 2019
406/27/18
Aircraft Release
Mach 0.7
35,000 ft
30 deg FPA
Accelerate to Cruise 
Start Condition
Mach 6
1,000 psf
Cruise at Constant Mach Number 
and Dynamic Pressure
DRM E: Hypersonic Cruise Surrogate
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GO1 Inert Test Article (ITA)
• In late 2015, Generation Orbit Launch 
Services, Inc. (GO) was awarded an 
opportunity to work with NASA AFRC 
through a Space Technology 
Announcement of Collaborative 
Opportunity
• GO1-ITA was designed to replicate the 
Outer Mold Line (OML) and mass 
properties of the empty configuration of 
the Generation Orbit Launcher 1 Rocket 
Vehicle
• The ITA weight was 1200 lb and the 
rocket vehicle is designed to be 2700lbs
• Project was to act as a risk reduction 
for the GOLauncher 1 (GO1) project
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GO1 Inert Test Article (ITA)
• Original ACO scope included a feasibility 
assessment for a flight test using the 
NASA C-20 A/C as a carrier platform for a 
release flight of the full weight ITA
• Resultant test objectives included:
– Demonstrating aircraft performance, handling 
qualities, aborted release maneuver of light-
weight ITA, and quantifying flight loads
• Project requirements included:
– Performing aerodynamics, loads, dynamics, 
and controls analyses to clear the test 
configuration consisting of the C-20A airframe, 
stores rack, and ITA for a captive carry flight 
test
– Performing integration between the ITA and the 
NASA C-20A aircraft
– Performing captive carry flight tests 
demonstrating the launch abort maneuver
606/27/18 CRASTE Conference
AFRC Airworthiness Process
06/27/18 7
Post Tech-Brief – The 
project Chief Engineer 
works directly with the 
AFRC Chief Engineer to 
provide project status
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Project Schedule
• The effort to substantiate the airworthiness 
of the aircraft, pylon, and ITA capability for 
a captive carry flight simulating an aborted 
launch and recovery maneuver began in 
earnest beginning of 2017
• The project completed the full AFRC 
briefing cycle in December 2017
806/27/18
Oct
2015
Apr
2016
July
2016
Oct
2016
Jan
2017
Apr
2017
July
2017
Oct
2017
Jan
2018
Jan 
2016
Eng Review
Signed ORD
Project 
Plan & 
SAA 
Signed
Fit Check 
and GVT
FRR
C-20 ITA  Release 
Feasibility Studies
Flights
AFSRB
Tech 
Brief
ITA 
Arrival
Project 
Start
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C-20 and ITA Description
• The NASA 502 C-20 is the military version of the Gulfstream GIII, a twin-
turbofan, swept-wing, business jet built by Gulfstream Aerospace 
Corporation
• The service ceiling of the C-20 is 45,000 ft, maximum speed is 340 Knots 
Calibrated Air Speed (KCAS) and a maximum Mach number of 0.85 
• ITA structure consisted of a composite fuselage and a metallic wing and 
control surfaces
906/27/18 CRASTE Conference
UAVSAR vs ITA
• The NASA Unmanned Aerial Vehicle Synthetic Aperture Radar (UAVSAR) is a 
pod mounted earth science instrument fielded by the NASA Jet Propulsion 
Laboratory
• The UAVSAR pod and pylon were exclusively designed and flight tested for 
use with the NASA C-20 in 2006-2008 
• The UAVSAR pylon design specifications were used to define the flight 
envelope for the GO1-ITA flight tests
1006/27/18
UAVSAR ITA
Length (in.) 129.6 262.8
Diameter (in.) 30 25.9
Mass (lbs.) 1,200 1,206.8
Ixx (lb-in2) 115,558 204,318
Iyy (lb-in2) 905,584 5,754,859
Izz (lb-in2) 899,509 5,747,653 UAVSAR
GO1-ITA
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Desired Release Condition
30°
35,000 ft MSL
0.70 M
1-sec
1-sec
1.0-g
Launch Abort Maneuver:
• Establish 0.05M below desired entry Mach (i.e. 0.73M for 0.78M entry)
• Set 500-deg TGT throttle setting and begin level acceleration to entry Mach
• At entry Mach number, initiate 2.0g pull to capture required pitch attitude
• Stabilize at 1.0g w/i ±1.0 sec of simulated release point
• Execute normal “nose-high recovery” maneuver
• Throttles remain fixed from initial acceleration to acceleration on recovery
Nz=2.0g
32,300 ft MSL
0.78 M
06/27/18 11CRASTE Conference
Flight Test Plan
• A build-up approach was undertaken to 
incrementally increase dynamic pressure and 
g-loading on the ITA
• The envelope was cleared to the extent 
required to perform the launch abort and 
recovery maneuver
• Flight Test Maneuvers:
– Steady Level Flight – Structural Dynamics 
Assessment
– Steady Heading Sideslips – Controllability 
Assessment
– Angle Captures – Controllability Assessment
– Push Over Pull Up – Loads Assessment
– Raps – Structural Dynamics Assessment
1206/27/18 CRASTE Conference
Aerodynamics and Propulsion Analyses
• Aerodynamics deltas of the GO1-ITA store were shown to be small and within the 
aerodynamic variations of the legacy/flown UAVSAR pod
– Analysis indicated possible issues with high-speed flight at Mach 0.82 and above
• Aero loads were developed using the worst-case combination of Euler and Navier
Stokes CFD, and were run at multiple flight conditions
• The C-20A aircraft engine operation and potential stagnation issue at the high-altitude 
and low-speed portion of the GO1-ITA’s aircraft recovery flight envelope was assessed
• Aircraft landing gear close proximity and aerodynamic interferences during take-offs 
and landings were assessed
1306/27/18
Euler Navier-Stokes
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GIII Simulator and Controls/HQ Analysis
• An engineering simulation, which models the GIII flight dynamics, was 
developed and validated for a prior flight project
• ITA aero and mass property models were implemented into the simulation 
• Simulation was used to hone in on the ideal entry conditions for performing 
the release maneuver
• Simulator provided aircraft dynamics for assessing ITA inertial loads
• Project confirmed that the captive carry                                                        
configuration did not cause any 
unacceptable degradation in aircraft                                                                  
stability and Handling Qualities (HQs)
1406/27/18 CRASTE Conference
Structures Analysis
• Aero loads were developed using the worst-case combination of Euler and 
Navier Stokes CFD, and were run at multiple flight conditions (by varying 
qbar, α, and β)
• ITA inertia forces & moments (including raps and launch abort recovery 
maneuvers) were obtained from the AFRC G-III simulator and Adaptive 
Compliant Trailing Edge flight data
• The GO1-ITA structural analysis, design and as-built drawings, work orders, 
and material certifications provided by Generation Orbit were reviewed and 
validated
• ITA Design Factors of Safety on Ultimate:
• No testing required
• Metallic: 2.25
• Composite: 3.0
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Structural Dynamics Analysis
• Finite Element Model (FEM) Development 
• Multiple ITA FEMs were created with increasing complexity over the project life cycle
• Ground Tests
• C-20 + ITA Ground Vibration Test (GVT) – July 2017
• Moment of Inertia (MOI) Test at GO’s facility – Oct. 2017
• ITA mini-GVT Checkout – Nov. 14, 2017
• ITA GVT rigid body frequencies were very close  
together (within ≈ 1 Hz) & much lower than UAVSAR
• Flutter Analyses of GIII + ITA
• Multiple GIII+ITA flutter analyses have been performed                                                    
over the project life cycle as complexity of the FEM                                                    
increasing and as FEM was updated with GVT & later                                                       
MOI data  
• Flight Flutter Testing 
• Supported flight planning & supported flights
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1) Stick FEM 2) Equivalent FEM 5) Full Detailed FEM 3) & 4) Detailed FEM  
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Instrumentation and Data Displays
• The project used a S-Band Quasonix EVTM transceiver. 
• Real-time telemetry data was processed and recorded on the ground.  The 
onboard data was archived post flight 
• Real-time data was viewed in the control room using Interactive Analysis and 
Display System (IADS)
1706/27/18 CRASTE Conference
Ground Testing
• Ground Vibration Testing – important for FEM model verification in support of flutter 
analysis
• Moment of Inertia Testing – verified loads, dynamics, and simulator models
• Loads and Deflection Test – verified structures analysis and instrumentation 
• ITA Telemetry Checks – verified data transmission prior to aircraft integration
• C-20 and ITA Telemetry Checks – verified data transmission prior to Combined System 
Test
• Combined System Test – verified integrated system prior to first flight
1806/27/18 CRASTE Conference
Flight Testing
• The project completed a high speed taxi test 
and three flights
• The third flight was dedicated to completing 
the launch abort release maneuver starting 
with a 15 degree pitch attitude and building 
up to the 30 degree pitch attitude
• The launch maneuver objective of a pitch-up 
to 30degs at Mach 0.70 and an altitude of 
35,000ft was completed during a third flight 
on December 12, 2017
1906/27/18 CRASTE Conference
Pilot Comments
• Rotation forces at takeoff not as noticeable as for UAVSAR pod 
• During rolling maneuvers (a.k.a. bank-to-bank rolls), ITA presence noticeable 
– Pendulum effect
– Slight bank overshoot
• Simulator gave a good 
representation of maneuver, 
to include roll rates, yoke forces,
and energy planning
• Executed ‘flight abort maneuver’ from multiple pitch angles
– 15, 20, 25 and 30 degrees pitch
– 15/20 degree pitch maneuvers very similar to mild “upset” training
– 25/30 degree pitch maneuvers higher attitude than normal but very controllable
• Four 30-deg / 0.70 M abort maneuvers flown
2006/27/18
Entry Altitude Mach at Pull-up Mach at FL350 Pitch at Release
33,400 ft 0.77 0.71 28-deg
33,300 ft 0.75 0.69 33-deg
33,200 ft 0.75 0.68 30-deg
33,100 ft 0.77 0.70 30-deg
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GIII Sim vs Flight
GIII Sim Flight
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Pilot Comments, cont’d
• Leaving throttles fixed throughout maneuver was a good idea
– A level accel 0.05M below entry airspeed resulted in stable engine power
– 500-deg TGT setting gave good recovery airspeed
• Release airspeed sensitive to pull-up ‘g’
– Need g-meter
– 2.0-g resulted in good
climb performance and was
very repeatable
• Recovery airspeed was always
safe as long as no delay in rolling
to 90-deg bank at recovery
– “Crisply” roll to 90-deg bank
– Even slight delays resulted in 10-20
knot recovery airspeed differences 
– Never approached stick shaker
• Summary
– Maneuver was simple and repeatable
– The simulator was an excellent tool in preparing for the profile
– The ITA appeared to have less drag in-flight than in the simulator
2206/27/18 CRASTE Conference
Conclusions and Project Challenges
• The project completed the primary goal of integrating the ITA onto the C-20 
and performing the launch maneuver at a 30 degree pitch up at a 0.70 Mach 
and an altitude of 35,000ft on the third flight
• Challenges:
– Managing expectations between a startup company culture and government 
culture
– Managing scope increase for a small budget project
– Getting a team with the right skillsets pulled together and up to speed on a short 
term project
– Maintaining an appropriate level of oversight with a company with no prior 
working relationship 
– Tailoring the airworthiness process appropriately to efficiently meet the goals of 
the project
2306/27/18 CRASTE Conference


Captive-Carry Flight Demonstration of an Inert Test Rocket Using a Business Jet as an Air Launch Platform

Captive-Carry Flight Demonstration of an Inert Test Rocket Using a Business Jet as an Air Launch Platform

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