Aerodynamic Database Development for the Hyper-X Airframe Integrated Scramjet Propulsion Experiments

TL;DR: In this paper, the authors provide an overview of the activities associated with the development of the Hyper-X aerodynamic database, including wind tunnel test activities and parallel CFD analysis efforts for all phases of the hyper-X flight tests.

Abstract: This paper provides an overview of the activities associated with the aerodynamic database which is being developed in support of NASA''s Hyper-X scramjet flight experiments. Three flight tests are planned as part of the Hyper-X Program. Each will utilize a small, non-recoverable research vehicle with an airframe integrated scramjet propulsion engine. The research vehicles will be individually rocket boosted to the scramjet engine test points at Mach 7 and Mach 10. The research vehicles will then separate from the first stage booster vehicle and the scramjet engine test will be conducted prior to the terminal decent phase of the flight. An overview is provided of the activities associated with the development of the Hyper-X aerodynamic database, including wind tunnel test activities and parallel CFD analysis efforts for all phases of the Hyper-X flight tests. A brief summary of the Hyper-X research vehicle aerodynamic characteristics is provided, including the direct and indirect effects of the airframe integrated scramjet propulsion system operation on the basic airframe stability and control characteristics. Brief comments on the planned post flight data analysis efforts are also included.

Summary

1 Introduction

• An important limitation of traditional logic programming as a knowledge representation tool, in comparison with classical logic, is that logic programming does not allow us to deal directly with incomplete information.
• In order to overcome this limitation, the authors propose to consider \extended" logic programs, that contain classical negation : in addition to negation-as-failure not.
• A \well-behaved" program has exactly one stable model, and the answer that such a program is supposed to return for a ground query A is yes or no, depending on whether A belongs to the stable model or not.
• The answer that the program is supposed to return for a ground query A is yes, no or unknown, depending on whether the answer set contains A, :A, or neither.
• The reason is that it interprets expressions like these as inference rules, rather than conditionals.

2 Answer Sets

• The semantics of extended programs treats a rule with variables as shorthand for the set of its ground instances.
• This set will consist, informally speaking, of all ground literals that can be generated using (i) the rules of the program, and (ii) classical logic.
• (Notice that the sign : stands there for negation-as-failure and thus corresponds to not in the notation of this paper.).
• The absence of an atom A in the stable model of a general program represents the fact that A is false; the absence of A and :A in the answer set of an extended program is taken to mean that nothing is known about A. Proposition 1.
• Every contradictory program has exactly one answer set|the set of all literals, Lit.

3 Representing Knowledge Using Classi-

• Sometimes the use of negation-as-failure in logic programs leads to undesirable results that can be eliminated by substituting classical negation for it.
• The situation will be di erent if classical negation is used: Cross :Train:.
• The closed world assumption for a predicate P can be expressed in the language of extended programs by the rule :P (x) not P (x): (3) When this rule is included in the program, not P and :P can be used interchangeably in the bodies of other rules.
• The claim that the employment information in the database is complete is expressed by the closed world assumption for Employed: :Employed(x; y) not Employed(x; y): Appending this rule to the program will add the literals :Employed(Jack;SRI);:Employed(Jane;Stanford) to the answer set.
• The rules are encoded in the following extended program: Eligible(x) HighGPA(x); Eligible(x) Minority(x);FairGPA(x); :Eligible(x) :FairGPA(x); Interview(x) not Eligible(x);not :Eligible(x):.

4 Reduction to General Programs

• For any predicate P occurring in , let P 0 be a new predicate of the same arity.
• The fact that the literals included in (5) indeed belong to the answer set of 6 can be con rmed by applying the Prolog query evaluation procedure to + 6 and to the queries FairGPA(Ann);HighGPA 0 (Ann); Interview(Ann): Queries with variables can be processed in a similar way.

5 Relation to Default Logic

• The stable model semantics can be equivalently described in terms of reducing logic programs to a xpoint nonmonotonic formalism| default logic, autoepistemic logic or introspective circumscription.
• Proposition 3. For any extended program , (i) if S is an answer set of , then the deductive closure of S is an extension of ; (ii) every extension of is the deductive closure of exactly one answer set of .

6 The Closed World Interpretation of

• Syntactically, general logic programs are a special case of extended programs.
• Moreover, every answer set of CW( ) can be represented in the form (14), where S is an answer set of .

7 Classical Negation in Disjunctive Databases

• The idea of rules with disjunctive heads has received much attention in recent years.
• It follows that Jack has an adequate income.
• The answer to a query may depend now on which answer set is selected.
• This example shows that there is a di erence between j as used in this paper and classical disjunction used in default logic.

8 Conclusion

• Extended logic programs and extended disjunctive databases use both classical negation : and negation-as-failure not.
• Their semantics is based on the method of stable models.
• Some facts of commonsense knowledge can be represented by logic programs and disjunctive databases more easily when classical negation is available.
• Under rather general conditions, query evaluation for an extended program can be reduced to query evaluation for the general program obtained from it by replacing the classical negation of each predicate by a new predicate.
• A semantic equivalent of a general logic program in the language of extended programs can be formed by adding the closed world assumption for all predicates.

Full text

AIAA 2000-4006
Aerodynamic Database Development
for the Hyper-X Airframe Integrated
Scramjet Propulsion Experiments
Walter C. Engelund,
Scott D. Holland,
Charles E. Cockrell, Jr.
NASA Langley Research Center
Hampton, VA
Robert D. Bittner
FDC-NYMA, Inc.
Hampton, VA
AIAA 18th Applied Aerodynamics Conference
August 14-17, 2000
Denver, Colorado
For permission to copy or republish, contact the American Institue of Aeronautics and Astronautics,
1801 Alexander Bell Drive, Suite 500, Reston, VA 20191-4344

AIAA-2000-4006
AERODYNAMIC DATABASE DEVELOPMENT FOR THE HYPER-X AIRFRAME INTEGRATED
SCRAM JET PROPULSION EXPERIMENTS
Walter C. Engelund,* Scott D. Holland,** Charles E. Cockrell, Jr. +
NASA Langley Research Center
and
Robert D. Bittner _t
FDC-NYMA, Inc., Hampton, VA
Abstract
This paper provides an overview of the activities
associated with the aerodynamic database which is be-
ing developed in support of NASA's Hyper-X scramjet
flight experiments. Three flight tests are planned as part
of the Hyper-X program. Each will utilize a small, non-
recoverable research vehicle with an airframe integrated
scramj et propulsion engine. The research vehicles will be
individually rocket boosted to the scramjet engine test
points at Mach 7 and Mach l 0. The research vehicles will
then separate from the first stage booster vehicle and the
scramjet engine test will be conducted prior to the termi-
nal decent phase of the flight. An overview is provided
of the activities associated with the development of the
Hyper-X aerodynamic database, including wind tunnel
test activities and parallel CFD analysis efforts for all
phases of the Hyper-X flight tests. A brief summary of
the Hyper-X research vehicle aerodynamic characteris-
tics is provided, including the direct and indirect effects
of the airframe integrated scramjet propulsion system
operation on the basic airframe stability and control char-
acteristics. Brief comments on the planned post flight data
analysis efforts are also included.
Nomenclature
o_ angle-of-attack (degrees)
[5 angle-of-sideslip (degrees)
• Vehicle Analysis Branch. Senior Member AIAA.
""Assistant Branch Head, Aerothermodynamics Branch,
Senior Member AIAA.
_Hvpersonic Airbreathing Propulsion Branch, Senior
Member AIAA.
,+Hypersonic Numerical Applications Group. Hyper-XProgram
Office.
Copyright(G2000AmericanInstituteofAeronauticsandAstronautics,
Inc.Nocopyrightis assertedin theUnitedStatesunderTitle 17,U. S.
Code. The U.S. Governmenthas a royalty-freelicense to exercise all
rights underthe copyrightclaimed herein forGovernmental purposes.
All otherrights arereservedby thecopyrightowner.
bref
CO
CL
CI
CIsa
CJl3
Cm
C,
CoO
Cnsa
CV
Cvl3
CY_5a
_a
_elv
r
lref
Hyper-X vehicle reference span
Drag force coefficient (drag,)
qooS,-ef
Lift force coefficient ( l/fi )
q_Sr,f
Rolling moment coefficient (r°lling moment)
q S,.efb,.ef
Rolling moment coefficient derivative due to
aileron deflection (per degree)
Rolling moment coefficient derivative with
respect to sideslip angle
Pitching moment coefficient (pitching moment)
q_S,.4"l,.ef
Yawing moment coefficient (),awing moment)
q_Sr_:fbrqf
Yawing moment coefficient derivative with
respect to sideslip angle
Yawing moment coefficient derivative due
to aileron deflection (per degree)
Side force coefficient (sidef°rce)
Side force coefficient derivative with respect
to sideslip angle
Side force coefficient derivative due to
aileron deflection (per degree)
aileron deflection (differential horizontal tail:
8,_,,.- 8tw ), degrees
elevator deflection (symmetric horizontal tail:
8nr + 8lw ), degrees
2
rudder deflection (_:_),
degrees
Hyper-X vehicle reference length
1
American Institute of Aeronautics and Astronautics

1
q_ freestream dynamic pressure (_p V_2)
Sre f Hyper-X vehicle reference area
Introduction
In 1996 NASA initiated the Hyper-X Program, a
jointly conducted effort by the NASA Langley Research
Center (LaRC) and the NASA Dryden Flight Research
Center (DFRC), as part of an initiative to mature the tech-
nologies associated with hypersonic airbreathing propul-
sion. zUnlike its predecessor, the U.S. National Aero-
Space Plane (NASP) program,-' Hyper-X is a very
focused program which offers an incremental approach
to developing and demonstrating scramjet technologies.
During the NASP program, attempts were made to de-
velop and integrate many new, unproven technologies
into a full-scale flight test vehicle. In hindsight, this was
an overly ambitious goal that was both technically and
programmatically unachievable, given the relative imma-
turity of the various technologies and the budgetary con-
straints of the time. By contrast, the primary focus of the
Hyper-X program is the development and demonstration
of critical scram jet engine technologies, using several
small, relatively low cost, flight demonstrator vehicles.
This philosophy is a direct outcome of NASA's "better,
faster, cheaper" approach to flight projects and programs
in general.
The primary goals of the Hyper-X program are to
demonstrate and validate the technologies, the experi-
mental techniques, and the computational methods and
tools required to design and develop hypersonic aircraft
with airframe-integrated dual-mode scramjet propulsion
systems. Hypersonic airbreathing propulsion systems,
studied in the laboratory environment for over 40 years,
have never been flight tested on a complete airframe in-
tegrated vehicle configuration. Three Hyper-X flight test
vehicles, the first two of which will fly at Mach 7, and
the third at Mach 10, will provide the first opportunity
to obtain data on airframe integrated scramjet propulsion
systems at true flight conditions. 3-5
The Hyper-X flight test program is first and foremost
designed to test the operation and performance of an air-
frame integrated dual mode scramjet propulsion system.
There are also a number of tier two goals of the program
that are primarily aerodynamics related. The Hyper-X
flight test program will provide a unique opportunity to
obtain hypersonic aerodynamic data on a slender body,
non-axisymmetric airframe. Because of the highly inte-
grated nature of the propulsion system with the airframe,
the traditional distinctions between vehicle aerodynam-
ics and propulsion are blurred. So in addition to the scram-
jet operational and performance data that will be obtained,
a tremendous amount of aerodynamics data will be gath-
ered during the flight tests, both during and after the engine
test, and will be telemetered back to ground stations in
real time for post flight analysis. In addition to basic air-
frame aerodynamic stability and control information, each
of the three Hyper-X Research Vehicle (HXRV) airframes
are heavily instrumented with surface pressure, temper-
ature and local strain gauge sensors.
Hyper-X Flight Experiments - Vehicle Design and
Mission Profile
The HXRV design draws heavily on past vehicle
configuration studies including the extensive NASP de-
sign database and several of the more recent U.S. hyper-
sonic vehicle mission studies. 6,7 Each of the three
HXRVs, also referred to as the X-43A flight vehicles, are
12 feet long, weigh approximately 2700 Ibs., and are
scramjet powered, lifting body configurations, with all
moving horizontal wings, and twin vertical tails with
rudder surfaces (Fig. 1). The scramjet flowpath, which
begins at the nose of the vehicles, utilizes the entire un-
derside of the forebody as a compression surface. The
scramjet engine combustor is located on the vehicle un-
dersurface, slightly aft ofmidbody, and the aftbody un-
dersurface comprises the external expansion surface for
the scramjet exhaust flow. The initial conceptual design
and internal subsystems definition for the X-43A config-
uration was performed by the former McDonnell Dou-
glas Aerospace (now Boeing Co.) - St. Louis group, sThe
scramjet engine flowpath definition and development
activity was conducted primarily by researchers at NASA
Langley Research Center. 9 The vehicle preliminary de-
sign (referred to as the Government candidate design)
was completed in October of 1996, and a team lead by
Micro Craft, Inc. ofTullahoma, TN, was selected to fab-
ricate and assemble the three X-43A research vehicles.
Figure 1. H)per-X Research Vehicle/X-43A geometty.
2
American Institute of Aeronautics and Astronautics