Concept#Study#of#a#Reusable# …space.uah.edu/Publications/AIAA_Region2_2017/Conference...• Pass"the"Von"Karman"Line"(100km)." ... Receive# Free#Space#Path#Loss#(400#km) ... •

AIAA CONFERENCE 2017 University of Alabama Huntsville

Concept Study of a Reusable Suborbital Launch Vehicle

Benjamin Thompson Ma/hew Haskell Jared Fuchs William Hankins

Presenters

1


MISSION INTRODUCTION

2

ObjecHve: Can undergraduate student organizaHons launch payloads to space? •  The Reusable Suborbital Launch Vehicle (RSLV) mission has

the primary inten>on of developing a space capable student launch vehicle.

Principle Constraints: •  Pass the Von Karman Line (100km).

•  Affordable by student funding sources. –  U>lize commercially available systems/propellant

•  Development >meline of under 3 years. –  Within a reachable TRL level of our student organiza>on


MISSION INTRODUCTION

3

SoluHon: MulHdisciplinary System •  To accomplish the mission a system is needed that can

u>lize two major student systems: Ballooning and Rocketry

30 50 70 90 110 130 150 170 190

210

6 8

10 12

14

206

191 180

170 161

184

165

150

138 128

176

159

146

135 126

157

143

132 122

114

129

117 107

99 92

120

109 100

92 86

93

82 73

66 61

96

83

74 67

61

81

71 63

58 53

65 49

47 65

65 32

17 15

20

Al<tud

e (km)

Balloon Assisted Rocket Concept •  Use a balloon to hoist

an op>mized rocket for a high al>tude launch –  Removal of drag forces

–  Substan>al increase in al>tude gain

–  Reduc>on in propellant investment/design


INTRODUCTION: PAST MISSION HERITAGE

4

Project Farside •  USAF research for high al>tude

sounding missions –  Launched in the 1950’s –  4-‐stage solid fuel rocket –  Es>mated al>tude 740 km

Project HALO (High AlHtude LiW-‐Off) •  Amateur team located out of

Huntsville –  Launched in 1994 –  Single stage hybrid rocket –  Es>mated al>tude of 66 km Project Farside

Launch (leH) and Rocket (right) (h/p://www.whiteeagleaerospace.com/opera<on-‐farside/)


CONCEPT OF OPERATIONS

5


RSLV SYSTEM OVERVIEW

6

Heavy Li` Balloon

Transi>on Ring Tether Lines

Transi>on Ring

Launch Plaborm Rocket Booster

*Not to scale

Launch Plaborm Tether Lines


BALLOON SYSTEM: OVERVIEW

7

Heavy LiW Balloon Two op>ons currently exist for heavy li` balloons: •  Super Pressure

–  Long dura>on balloon –  More efficient –  Difficult to manufacture

•  Zero Pressure –  Easier to manufacture –  Requires ballasts

•  Both types of balloons will sa>sfy mission requirements

•  Al>tude stability (over short dura>on) is the primary concern

Balloon Performance Graph Source: Springer, Engineering Fundamentals of

Balloons

>100kg Payload ≈ 2x102 m3 Balloon Volume


BALLOON SYSTEM: AVONICS

8

Mission FuncHons •  The gondola avionics perform the crucial func>on of tracking the

vehicle during ascent, providing real >me telemetry data, and igni>ng the booster upon command

Sensor •  In order to perform these func>ons, a variety of sensors are needed

including a GPS, pressure sensors, accelerometers, and gyroscopes –  From these sensors, a go-‐no-‐go decision can be made from the ground sta>on

before booster igni>on CommunicaHon •  For in flight communica>on a Digi Xbee SX radio will be used. The

APRS (Automa>c Posi>on Repor>ng System) will be available for redundancy and recovery purposes

Digi Xbee SX Performance Transmissio

n Receive Free Space Path Loss (400 km) Ground StaHon Transmission Req.

30 dB -‐113 dB (Low Data Rate) 143.6 dB >30 dB


BALLOON SYSTEM: OVERVIEW

9

Launch Setup •  Launch plaborm

tethered to transi>on ring

•  Transi>on ring interfaces with balloon

•  Quan>ty of transi>on ring tether lines determined by balloon gore count

•  Tether line length TBD by balloon burst criteria and sway

•  Plaborm Material : 6061-‐T6 Aluminum


BALLOON SYSTEM: HIGH ALTITUDE

High AlHtude IgniHon •  Objec>ves

–  Keep electronics warm and func>onal –  Keep motor warm

•  Commercial rocket propellants need to be kept above 0F to reliably ignite –  Adverse affects include low burn rate and grains suscep>ble to cracking

•  Current considera>ons include –  E-‐matches –  Thermite –  Head End Igniter Grain

•  Further research necessary

10


ROCKET BOOSTER: OVERVIEW

11

Airframe •  Carbon fiber body tubes, 0.1524 meters (6 in.) in diameter •  Minimum diameter rocket design •  Aoaching fins via fin can system •  Fiberglass nose cone, Von Karman profile, aluminum nose >p with

threaded rod Propulsion •  Pro150 O-‐8000 solid fuel motor Recovery System •  Single drogue chute, 0.2 meter diameter •  Three primary parachutes, 0.6 meter diameter Payload/Avionics •  Avionics in nose cone to make radio transmission easier

v  (cannot transmit through carbon fiber) •  Antennas will be placed as necessary •  Payload will go inside of fiberglass coupler


ROCKET BOOSTER: OVERVIEW

12


•  Plan to conduct compression tests on all components of the rocket once they are made •  Es>mated max compressive strength of standard carbon fiber composite tubing:

5.70 x 108 N / m2 (82,671.5 psi) (hop://www.performance-‐composites.com/carbonfibre/mechanicalproper>es_2.asp)

ROCKET BOOSTER: MATERIAL ANALYSIS

13

Airframe Analysis

EquaHon Variables Result

F = ma •  m = 47 kg •  a = 310 m / s2 14,570 N

Cross Sec<onal Area = π(r21 – r22)

•  π = 3.14159 •  r21 = 0.00581 m2 •  r22 = 0.00605 m2

0.000754 m2

σnormal = F / Surface Area •  F = 14,570 N •  Surface Area = 0.000754 m2 19,323,607 N / m2

Safety Factor x σnormal •  Fnormal = 19,323,607 N / m2 •  Safety Factor = 20

386,472,149 N / m2 (56,053 psi)


ROCKET BOOSTER: FIN FLUTTER

•  Equa>ons created in excel spreadsheet with the help of Davis Hunter •  Calculated at 100,000 feet (30 km)

14

Fin Flueer Analysis

EquaHon Variable Result

Aspect Ra<o (AP) = Span2 / Area •  Span = 6 in. •  Area = 36 in.2 1

Taper Ra<o (TP) = Tip Length / Root Chord Length

•  Tip Length = 3 in. •  Root Chord Length = 9 in. 0.333

x = { 39.3(AP)3 } / { (Fin Thickness / Root Chord)3 * (AP + 2) }

•  AP = 1 •  Fin Thickness = 0.0625 in. •  Root Chord = 9 in.

39,116,390

y = { Air Pressure(Al<tude) / Air Pressure(Sea Level) } * { (TP + 1) / 2 }

•  Air Pressure(A) = 0.162 psi •  Air Pressure(S) = 14.7 psi •  TP = 0.333

0.007347

Flu/er Velocity = (Speed of Sound * Shear Modulus) / (x * y)

•  Speed of Sound = 968 `. / s •  Shear Modulus = 7,830,000 psi •  x = 39,116,390 •  y = 0.007347

26,374 `. / s

% = (Max Velocity / Flu/er Velocity) * 100 •  Max Velocity = 1,165 `. / s •  Fluoer Velocity = 26,374 `. / s 4.42 %


ROCKET BOOSTER: AVONICS

15

FuncHons •  The rocket avionics are limited compared to the balloon avionics with

its only func>on to ini>ate de-‐spin and deploy the parachutes –  During por>ons of booster flight, GPS al>tude determina>on is not available

due to speed and al>tude locks •  In order to determine al>tude, dead reckoning will be used with data

coming from three accelerometers and gyroscopes –  Early avionics simula>ons show that error for this process will fall under 2%

CommunicaHon •  Ideally, the rocket will remain in contact with the ground sta>on

throughout the flight, however no remote commands will occur •  Digi Xbee SX radio has enough range for use in the booster system

–  Antennas will be placed as necessary to maintain LOS with ground during spinning


RSLV SIMULATION DEVELOPMENT

16

Six Degree of Freedom SimulaHon •  To evaluate performance of the RSLV at high

al>tude a custom simula>on was created to answer the following –  Stabiliza>on at low density –  Drag with changing density

SimulaHon Environment •  MATLAB Simulink

–  Numerical integra>on for solu>ons to ODE’s Primary Physics Considered •  Drag/Li` Forces

–  Barrowman formula>ons with extensions for compressible flow (Prandtl-‐Glauert approxima>on)

–  Small angle approxima>ons •  Damping Forces

–  Barrowman formula>ons and custom deriva>ons •  Angular Moments

–  Euler equa>ons for ridge body dynamics (along principle axes of iner>a)

Compute forces/moments in

rocket body frame

Translate resul>ng accelera>ons into flat earth frame

Add gravity (defined in earth

frame)

Numerically integrate for posi>on

(earth frame)

SimulaHon Flow


RSLV MISSION PERFORMANCE ANALYSIS

17

Trajectory SimulaHons •  The 6-‐DOF simulator is applied to determine the forces and al>tude gains

for the RSLV at desired flight al>tudes

IniHal AlHtude Mass Max Velocity Max AcceleraHon Max Q Apogee Time to Apogee

25 km 44 kg 1160 m/s 305 m/s2 25880 N/m2 92.3 km 125 s

30 km 44 kg 1165 m/s 310 m/s2 13960 N/m2 100 km 125 s

35 km 44 kg 1168 m/s 312 m/s2 7504 N/m2 107 km 125 s

ImplicaHons •  Flight Al>tude should be around 30km for best performance to

engineering challenge •  Intended vehicle can reach space •  Mass op>miza>on is cri>cal

O-‐8000 Motor Data Max Thrust Impulse Isp Burn Time Casing Mass Propellant Mass 8034 N 40960 Ns 224 s 5.1 s 14.06 kg 18.61 kg


RSLV BOOSTER STABILITY ANALYSIS: SPIN STABILIZATION

18

High AlHtude StabilizaHon •  It was iden>fied early on that spin-‐stabiliza>on, if possible, was the preferred method •  6-‐DOF simula>ons were run to iden>fy its performance

–  A simulated thrust misalignment of 0.1o was applied during burn across varying fin cants to achieve different roll rates

–  0.34o fin cant obtains a 3 Rev/s roll

De-‐Spin •  To safely deploy the recovery system the rocket will need to be de-‐spun, this will be done using a standard

yo-‐yo de-‐spin mechanism

IniHal Roll Rate Final Roll Rate Un-‐stretched Length Spring Constant Mass 180o /s 1o /s 0.4 m 233 N/m 0.263 kg 360o /s 1o /s 0.4 m 1882 N/m 0.265 kg 720o /s 1o /s 0.4 m 15121 N/m 0.266 kg

radians

radians

radians

meters

meters

meters


RSLV RECOVERY SYSTEM ANALYSIS: BOOSTER

19

System Deploy AlHtude Diameter Chute Lines Max Line Tension Max Pressure

Drogue (x1) 100 km 0.2 m 5 165 N 13140 N/m2

Primary (x3) 4 km 0.6 m 10 378.9 N 744 N/m2

Landing Velocity Max Velocity Max AcceleraHon DriW 9.96 m/s 997 m/s 402 m/s2 61.9 km

Recovery SimulaHons •  Wind data from the Black Rock launch site is used


RSLV RECOVERY SYSTEM ANALYSIS: GONDOLA

20

Recovery SimulaHons •  Wind data from the Black Rock launch site is used

System Deploy AlHtude Diameter Chute Lines Max Line Tension Max Pressure

Primary (x1) 30 km 1.5 m 10 19.96 N 113 N/m2

Landing Velocity Max Velocity Max AcceleraHon DriW 10.0 m/s 62.9 m/s 1 m/s2 51.6 km


RSLV BALLOON DRIFT ANALYSIS

21

Balloon DriW SimulaHons •  Wind data from the Black Rock launch site is used to consider the balloon dri`

Apogee Ascent Velocity DriW

30 km 3.0 m/s 20.6 km


RSLV SCALE TESTING

22

Scale TesHng ObjecHves With a limited budget (under $100) we want to address several big ques>ons: •  Test launch gondola and rail design

–  Is the two short rails enough for a stable ground launch?

•  Balloon assembling / manufacturing –  Iden>fy unforeseen challenges in crea>ng a custom balloon?

•  Balloon puncture method –  Will the rocket puncture the balloon at low speeds?

•  Gondola launch stability –  How will the gondola and balloon respond to rocket thrust?


RSLV SCALE TESTING: ROCKET

23

Scale Launch Plaborm / Rocket Launch Guide Close-‐up

Scale Rocket Design •  Minimum diameter model rocket •  C-‐6 Motor •  Loaded Mass: 50g

Scale Gondola Design •  3-‐D printed frame •  Mass: 100g 46.6cm

Launch Guide

Launch Rail

Blast Shield

2.48cm

10.28cm

Carbon Fiber Rail


RSLV SCALE TESTING: BALLOON

24

Heat Seal Close-‐up

Scale Balloon Design •  Pumpkin Shape •  9 Gores •  Polyethylene (0.7 mil) •  Custom heat sealing •  Volume: 9.63 m3

55.88cm

91.44cm

Gore Seals


RSLV SCALE TESTING: SHROUD LINES

25

Indoor Fill TesHng •  4 Ground tether lines (3.0m) •  4 Gondola hoist lines (2.1m) •  Connected to balloon gores at circumference •  Mass: 170 g

Gondola Hoist Lines Tether/Hoist Line

ConnecHons


RSLV SCALE TESTING: RESULTS

26

Scale Flight Results •  Two aoempts made, both unsuccessful due to weather and balloon issues – Winds greater then 1 m/s prevented balloon alignment – Micro-‐holes in balloon leaked helium on flight line

Lessons Learned •  Balloon manufacturing techniques

–  Several methods tried and improvements made on each aoempt.

–  Significant progress in tes>ng balloon shroud line design •  Gondola Launch Plaborm

–  Sta>c ground tests of the model rocket launched from the plaborm successful.


CONCLUSION

27

Student Suborbital Launch Vehicle Possible? •  Ini>al research and development has shown that a balloon launched rocket system has the poten>al to be an amateur suborbital launch vehicle –  Commercial systems can be used to achieve mission goals – Design is within developmental reach of a student organiza>on

Future Plans •  Pursue funding for full mission development •  Refine simula>ons •  Scale tes>ng

AIAA CONFERENCE 2017 University of Alabama Huntsville 28

QuesHons?

Documents

Concept#Study#of#a#Reusable# …space.uah.edu/Publications/AIAA_Region2_2017/Conference...• Pass"the"Von"Karman"Line"(100km)." ... Receive# Free#Space#Path#Loss#(400#km) ... •