Analysis completed since the test suggests that all test objectives were met This claim will be verified in the coming weeks as the data is examined further Final disposition of test objective success will be documented in a final reportsubmitted to NASA stakeholders (early August 2015) Expect conference paper in early 2016 Data products and observations made during testing will be used to refinecomputational models of Nano-ADEPT Carbon fabric relaxed from its pre-test state during the test System-level tolerance for relaxation will be driven by destination-specific andmission-specific aerothermal and aerodynamic requirements Bonus experiment of asymmetric shape demonstrates that an asymmetricdeployable blunt body can be used to generate measureable lift With a strut actuation system and a robust GN&C algorithm, this effect could beused to steer a blunt body at hypersonic speeds to aid precision landin

Brivkalns, C.

Cassell, A.

Kruger, C.

Makino, A.

McDaniel, R.

Smith, Brandon

Swanson, G.

Venkatapathy, E.

Yount, B.

Zarchi, K.

NASA Technical Reports Server

Nano-ADEPT  
Aeroloads Wind Tunnel Test 
 
 
 
International Planetary Probe 
Workshop (IPPW-12) 
15-19 June 2015 
Cologne, Germany 
 
 
 
Brandon Smith (presenter) 
NASA Ames Research Center 
Moffett Field, CA, USA 
brandon.p.smith@nasa.gov 
Industry Partners: 
Bally Ribbon Mills 
Thin Red Line Aerospace 
CFDRC 
 
Co-Authors: 
A. Cassell, B. Yount, C. Kruger, 
C. Brivkalns, A. Makino, K. Zarchi, 
R. McDaniel, E. Venkatapathy 
NASA Ames Research Center 
G. Swanson 
ERC Inc. / NASA Ames Research Center 
 
https://ntrs.nasa.gov/search.jsp?R=20160001281 2019-08-31T04:12:32+00:00Z
ADEPT 
Outline 
•  ADEPT background 
•  Nano-ADEPT 
development roadmap 
•  Test overview and 
objectives 
•  Test articles: solid and 
fabric 
•  Test matrix & execution 
 
•  Notable findings 
•  Video highlights 
•  Conclusions & next steps 
2 
Fabric model rear view mounted on sting in 7x10 
Foot Wind Tunnel at NASA Ames Research Center 
IPPW-12     15-19 June 2015     Cologne, Germany 
ADEPT ADEPT:  
Adaptable Deployable Entry and Placement Technology 
•  ADEPT is a mechanically deployed Entry, Descent, and Landing (EDL) system 
•  Stows during launch and cruise (like an umbrella) 
•  Serves as both heat shield and primary structure during EDL 
  
•  Nano-ADEPT is the application of ADEPT for small spacecraft where volume is a 
limiting constraint 
–  NanoSats, CubeSats, other secondary payloads, etc. 
 
•  Why Nano-ADEPT? 
•  Achieve rapid technology development extensible to large ADEPT applications 
•  Give rise to novel applications for small spacecraft by offering an entry system 
6 m diameter ADEPT-Venus  
in cruise (left) and entry (right) configurations 
0.7 m diameter Nano-ADEPT  
shown with notional 2U chassis payload 
3 IPPW-12     15-19 June 2015     Cologne, Germany 
ADEPT 
Nano-ADEPT Development Roadmap to TRL 5 
De
plo
ym
ent
 Pr
oto
typ
es Subsonic Aeroloads  
Wind Tunnel 
Sounding Rocket  
Flight Test Sys
tem
-Le
vel
 Ar
c J
et  
(SP
RIT
E-C
) 
Ejection from 
primary spacecraft 
Deployment 
Pre-Entry 
orientation 
Peak heat rate 
Thermo-structural 
loads 
FSI 
Landing loads 
Aero stability 
Shear pressure 
Component 
Structural Loads 
Shape 
Knowledge 
Gore Deflection 
(Static FSI) 
Fabric edge 
buzz/flutter 
(Dynamic FSI) 
Flight-like design 
Deployment 
reliability 
Interface with 
primary payload 
Achievable  
fabric pre-tension 
Tip-off rates 
Tech Maturation for 
Mission Infusion 
Tension 
maintenance 
under load 
Fabric system 
Primary geometric 
features of system-level 
arc jet tests (SPRITE-C) 
Θc = 55º 
Rn= 0.13 m 
Rb= 0.18 m 
Rn/Rb= 0.72 Primary geometric features of 
deployment prototypes, 
subsonic aeroloads wind tunnel 
test articles, sounding rocket 
flight test, and some DRMs 
0.70 m 
Θc = 70º 
Rn= 0.25 m 
Rb= 0.35 m 
Rn/Rb= 0.71 
4 
•  Strategy addresses technical challenges with four system-level tests 
•  Common geometric features between design reference missions (DRMs), ground 
tests, and flight test provide ground-to-flight traceability 
1 
2 
2 
1 1 
1 
Config. 
Config. 
IPPW-12     15-19 June 2015     Cologne, Germany 
ADEPT 
Aeroloads Test Overview and Objectives 
Test Objective Instrumentation 
Obtain static deflected shape and 
pressure distributions while varying pre-
tension* at dynamic pressures and angles 
of attack relevant to Nano-ADEPT entry 
conditions at Earth, Mars, and Venus. 
 
 
 
 
 
 
Photogrammetry; 
String potentiometers; 
Outer Mold Line (OML) static 
pressure taps 
Observe dynamic aeroelastic behavior 
(buzz/flutter) if it occurs as a function of 
pre-tension, dynamic pressure, and angle 
of attack. 
High speed video;  
Strut load cells 
Obtain aerodynamic forces and moments 
as a function of pre-tension, dynamic 
pressure, and angle of attack. 
Internal balance 
5 IPPW-12     15-19 June 2015     Cologne, Germany 
•  Testing was completed in seven business days at the US Army’s 7x10 Foot Wind Tunnel located at NASA Ames (27-Apr to 5-
May 2015) 
•  Shared funding was provided through NASA STMD GCDP ADEPT program (FY15) and a NASA Ames Center Innovation Fund 
Award (FY14) 
•  Test objectives trace to technical challenges identified by the ADEPT development team 
•  Rich data set was obtained through instrumentation suite designed to be redundant yet non-invasive 
Test Article Patterning Photogrammetry Solution 
Overlay 
-20º AoA 
*Tension in the carbon fabric is caused by two 
sources: ”pre-tension” resulting from the 
mechanical deployment of ADEPT prior to 
atmospheric entry and additional tension resulting 
from the aerodynamic load during entry 
Strut Load Cell Check Outs 
ADEPT 
Test Approach: Two Test Articles 
Fabric test article 
6 
Solid test article 
•  Simulates fabric test article with infinite pre-tension 
•  First article to be tested in the tunnel 
 
Common pressure 
tap pattern 
 
 
Common sting/
balance interface 
 
IPPW-12     15-19 June 2015     Cologne, Germany 
ADEPT 
Fabric Test Article Details 
7 
•  Ribs and struts (two per rib) are oversized compared to flight 
to comply with tunnel safety requirements and maximize 
use of COTS parts for cost savings 
 
•  String potentiometers are attached at mid-gore to give a live 
measure of deflection in the control room and provide a 
global view of gore deflections in lieu of photogrammetry 
view obstructions  
•  Blue lights indicate power to strut load cells 
 
0º gore left unpainted 
to isolate effect of 
photogrammetry paint 
on fabric stiffness 
 
White speckle paint is 
for photogrammetry 
surface tracking 
IPPW-12     15-19 June 2015     Cologne, Germany 
•  Flight-like carbon fabric skirt includes key features such as 
carbon yarn stitching and seam resin infusion 
 
•  Central nut moves all struts simultaneously to pre-determined 
positions to induce a known pre-tension in fabric (based on pre-
test measurements – 20 lbf/in, 10 lbf/in, 5 lbf/in, 2 lbf/in) 
•  Note that fabric test article does not deploy from a fully 
stowed state 
ADEPT 
Photron High Speed  
Video (500 fps)  
Photogrammetry 
3D Imaging 
Nano-ADEPT Solid Test Article @ +20 deg AoA 
Test  Matrix & Test Execution 
•  Photogrammetry and high speed video data 
were recorded at most test points 
•  Solid article was tested first 
–  Q sweeps from 0-100 psf (bounds peak dynamic 
pressure for Nano-ADEPT Mars DRMs and some 
entry from LEO DRMs) 
–  AoA/Yaw from -20 to +20 
–  Repeats 
 
•  Fabric test article covered same range of Q and 
AoA as the solid test article 
–  Four pre-tension “nut settings” were planned:  
•  20, 10, 5, 2 lbf/in 
 
•  Behavior of test article warranted modification 
of test matrix in real time 
–  ~40% loss of pre-tension after the first run at 20 
lbf/in due to fabric relaxation 
–  Fabric was completely slack at 5 lbf/in nut setting 
 
•  Added to test matrix during test execution: 
–  20 lbf/in pre-tension based on in-tunnel 
measurement (post-relaxation) 
–  Asymmetric shape (bonus experiment) 
8 IPPW-12     15-19 June 2015     Cologne, Germany 
Control Room 
ADEPT 
Static Pressure Data 
•  Static pressure taps on both test articles provided repeatable data (example 
shown below: solid test article pressure coefficient @ 100 psf) 
•  Instrumentation integration approach worked well and could be repeated for 
flight test 
•  Data is presently being compared to CFD solutions 
9 Fabric test article pressure coefficient @ 100 
psf (20 lbf/in measured pre-tension) 
 
 
C P
−1
−0.8
−0.6
−0.4
−0.2
0
0.2
0.4
0.6
0.8
1
-20º AoA 0º AoA +20º AoA 
 
 
C P
−1
−0.8
−0.6
−0.4
−0.2
0
0.2
0.4
0.6
0.8
1
 
 
C P
−1
−0.8
−0.6
−0.4
−0.2
0
0.2
0.4
0.6
0.8
1
 
 
C P
−1
−0.8
−0.6
−0.4
−0.2
0
0.2
0.4
0.6
0.8
1
IPPW-12     15-19 June 2015     Cologne, Germany 
Pressure tap 
ADEPT 
Bonus Finding: Asymmetric Shape 
•  Two pairs of struts were shortened to give the 3 o’clock gore a cone angle of ~67º (compared with 70º 
for the rest of the gores) 
–  Tension nut was set to 20 lbf/in nut setting so results may be compared with the same symmetric nut setting 
•  Resulted in offset of zero-moment angle of attack from 0º (symmetric) to +2.4º (asymmetric) 
–  See yaw moment coefficient plot below 
•  At hypersonic speeds, the lift generated by deflecting gores could be used for vehicle control 
10 
67° 
67° 
70° 70° 
70° 
70° 
70° 70° 
Shortened 
strut pairs 
20 lbf/in nut setting; Q = 100 psf Front View Side View 
IPPW-12     15-19 June 2015     Cologne, Germany 
ADEPT 
Conclusions and Next Steps 
•  Analysis completed since the test suggests that all test objectives were met 
–  This claim will be verified in the coming weeks as the data is examined further 
–  Final disposition of test objective success will be documented in a final report 
submitted to NASA stakeholders (early August 2015) 
–  Expect conference paper in early 2016 
•  Data products and observations made during testing will be used to refine 
computational models of Nano-ADEPT 
•  Carbon fabric relaxed from its pre-test state during the test 
–  System-level tolerance for relaxation will be driven by destination-specific and 
mission-specific aerothermal and aerodynamic requirements 
 
•  Bonus experiment of asymmetric shape demonstrates that an asymmetric 
deployable blunt body can be used to generate measureable lift 
–  With a strut actuation system and a robust GN&C algorithm, this effect could be 
used to steer a blunt body at hypersonic speeds to aid precision landing 
11 IPPW-12     15-19 June 2015     Cologne, Germany 
ADEPT 
Not pictured: 
Kerry Zarchi 
Ryan McDaniel 
Sameera Gunatileka 
Ethiraj Venkatapathy 
Aeroloads Wind Tunnel Test Team Photo 
12 


Nano-ADEPT Aeroloads Wind Tunnel Test

Nano-ADEPT Aeroloads Wind Tunnel Test

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