Case Studies: 2 Launch Vehicle Mishaps Titan IV, Pegasus XL

AIAA OC ASAT, May 2014

Returning the Pegasus XL

Winged Launch Vehicle to

Flight

Pete Young, Col., USAF (Ret.)

May 4, 2014

1


Overview

• Provide background on Return-to-Flight

– Pegasus XL

• Emphasis on

– Determination of mishap root cause

– **Other significant factors**

2


Pegasus “Standard”

Winged, aircraft-launched small satellite

launcher – DARPA initiated program

Prime contractor: Orbital Sciences

Corporation, Dulles VA

Payload: 635 lbs to LEO

First flight April 1990, 8 missions total 3


Pegasus XL heritage

• Pegasus XL “stretch” proposed to provide

increased payload performance (635# to

840# to LEO)

- Larger solid motors, minor planform

changes

4


“Stretched” Pegasus XL

5

http://www.orbital.com/Prods_n_Servs/Products/LaunchSystems/Pegasus/expanded.html


First P-XL flight, June 28, 1994 – Space Test Program STEP 1

Satellite – SDI/BMDO payload

- P-XL “departed from controlled flight” during first stage burn,

transonic flight regime

- Vehicle destroyed by VAFB Range –

- Root cause: sub-marginal flight stability coefficients derived by

CFD-based extrapolation of Pegasus-Standard aero data

6


2nd Pegasus XL mission: Space Test Program STEP-3 satellite

- Another SDI/BMDO payload

- VAFB launch scheduled for June 22, 1995

My personal situation:

- Newly promoted, named as incoming STP SPO Director

effective July 1, 1995

- Invited to VAFB as a “guest VIP observer”

Show STEP-3 videotapes --

7


Aftermath of STEP-3 Launch Failure

• “Root cause” readily identified: technician error epoxying

foam guideblock to Stage II nozzle

• “Fix and fly” feasible strategy -- ?

• But – two successive XL failures! And for different

reasons!

• Successful 2nd and 3rd stage flight yet to be

demonstrated…

8


1994-1995 -Small Launch Vehicle

Programmatic Situation

• A ‘very bad year’ for small launch vehicles

– Lockheed Martin LMLV and EER Conestoga

• Launch failures on first flights!

– Two successive Pegasus XL failures!

• Pentagon guidance – “Terminate Pegasus XL program ASAP!”

– Extreme DoD reluctance to sponsor a third P-XL flight – and possible third successive failure

• However…substantial P-XL payload backlog

– 14 Air Force, NASA, & commercial smallsats

9


P-XL Payloaders’ Dilemma

• Fundamental problem: NO practical launch alternatives for

backlogged payloads

– Shuttle, Delta, Taurus, Ariane, Proton, Titan, others

• Payload SPOs unwilling to “fix and fly” and risk another

launch failure – total lack of customer confidence

• But…STP obligated to provide orbital flight for customers!

10


Pegasus XL Return-to-Flight Program

July 1995 – requested and received permission from Gen Lester

Lyles to create a P-XL RTF initiative

My ground rules:

- personally selected technical and management support

- fly again when ready (and not before!)

- involvement of Orbital Sciences and all payload customers

- thorough review of ALL areas of concern, not just latest

root cause/flight anomaly

11


Return-to-Flight Methodology

• Investigation to determine 2nd mission “root cause(s)” and corrective action(s)

• Review of P-XL development pedigrees and qualification processes

• OSC-requested review of company procedures and practices

– Dulles,Virginia; Phoenix, Arizona; and VAFB California facilities

12


Major P-XL return-to-flight issues

• Redesign and retest of the Stage I/II separation

mechanisms

• Re-analysis of control surface flutter margins

• Thorough review of Stage II solid rocket motor

nozzle thermal margins

• Comprehensive review, and changes, of company

practices in Virginia, Arizona, California

13


REX II Mission Planning

• Drop zone: approx. 50 miles west of

Monterey Peninsula

• Launch date/time: March 8, 1996, 1745

PST

• Chase support: Edwards AFB F-16, F-18

14


Week of Launch

• Launch readiness briefings to AF senior

management and REX II customer

• Late breaking issues: failure of Parker-Hannifin

master servo controller; satellite ring antenna

damage; overflights by MIR, satellites, space

debris

• “Skeptical” media coverage!

15


Week of launch

• L-1011 “Stargazer” arrived VAFB 3 days

prior; very smooth integration of P-XL and

payload

16

http://www.air-and-space.com/20020201 Vandenberg/16 L-1011 N140SC Orbital Pegasus HESSI right front l.jpg


REX II Postscript

• Flawless launch and orbit insertion

• Vehicle deployed solar panels on first rev

• REX II mission totally successful

– Orbital operations turned over to US Naval

Academy Astronautics Department, operated

for several years by USNA students!

17


Pegasus XL postscript

• REX II was the 10th Pegasus mission

attempted (1996)

• OSC launched the 42th Pegasus mission

last June

18


The L-1011 rolls!

Show REX-II

Video

19


Questions?

20

BACKUPS

AIAA OC ASAT, May 2014 21


My Background

• Multiple AF, NRO and MDA system

program office (SPO) assignments, 1977-

2013

1. Satellite development and launch

integration

- Peacekeeper (MX), Space Shuttle, Titan

ELVs(T-II, T-III, T-IV), Taurus

22


Pegasus XL Return-To-Flight –

“Changing the Culture”

23


Next P-XL Mission/Payload

• Space Test Program empowered to set payload

launch priorities (!)

• REX II - two AF Rome Laboratory experimental

payloads

- 250 lb payload, 30” diameter, 22” high

– 450 nm circular polar orbit

24


P-XL and Kavli Center for Astrophysics’

(ex-MIT-CSR) HETE satellite

• SACB/HETE mission failed April 1996

– Root cause: separation battery internal shorting

• HETE II reflight successful – September

2000!

– L-1011 staged from Kwajalein, satellite

inserted into circular, equatorial orbit

– Satellite has made phenomenal astrophysics

measurements on transient Gamma Ray Bursts

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Documents

Case Studies: 2 Launch Vehicle Mishaps Titan IV, Pegasus XL