Goldie, J. H.

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9INTRODUCTION TO BOEING PAPERS ON DYNA-SOAR PROJECT
By John H. Goldie
Boeing Airplane Company
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The preceding papers of this conference have been largely descrip-
tions of research activities and results. The papers following the
present paper will present discussions of the engineering applications
of these data to specific problems of the Dyna-Soar. For example, the
mission planned for Dyna-Soar is limited to earth-orbital flight or
less. Therefore, data and trends presented in the paper by Thomas J.
Wong, Glen Goodwin, and Robert Sly and in the paper by Frederick C.
Grant do not apply directly to Dyna-Soar.
Papers by John F. Milton, G. E. Ledbetter, and Max T. Braun, which
follow the present paper, will describe the results of Phase Alpha.
One general question frequently asked about Phase Alpha is, "Why, of
all possible reentry bodies, were only nine specific shapes chosen
for detailed study?" Many additional concepts were examined at least
briefly. It was believed vital that at least one configuration be
examined in each of the four following prominent classes of reentry
devices: modified ballistic_ lifting bodies, winged bodies, and variable-
geometry shapes. Within each of these classes , several shapes were con-
sidered to determine whether the results were common to all designs within
that class. If so, the choice was rapidly narrowed. For example, two
modified ballistic shapes were analyzed for several weeks to discover
whether adding a variable-angle skirt or movable fins to a simple shape
would provide better (L/D)MAX and lower weight than other ideas. When
these shapes did not prove to be better, they were abandoned. In the
lifting-body class, a shape similar to the Ames M-2a was examined and dis-
carded for stability reasons. Two different structural concepts for the
Ames M-2b were considered; one proved to be somewhat inferior and was
dropped.
It was believed very desirable to have data on a spectrum of
glider configurations having values of (L/D)MAX from lto 3 in order
to determine the trends of weight and performance. Four different
designs with low (L/D)MAX were investigated and the choice was nar-
rowed to one. For variable-geometry configurations, a number of sug-
gestions were eliminated with essentially no formal design work; an
autogiro was one of these.
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It would have been very desirable to carry all these configurations
through complete design and evaluation rather than narrowing from
21 configurations to 9 as was actually done. The effective design
period of Phase Alpha was only eight weeks and the funds were limited.
Attempting even as manyas nine preliminary design studies in parallel
was considered risky, but all of these were carried to conclusion. The
final design of each is believed to be feasible although varying amounts
of development time and risks are required.
Completion of even limited preliminary designs of this manybodies
needed a great deal of help from other highly competent industrial
organizations. In somecases, the idea for the reentry device originated
with one of these companies and all the subsequent design was done by
them. In other cases, the companyprovided necessary technical data and
consultation. In every instance, Boeing Airplane Companysupervised the
work and must accept full responsibility for the final designs to be
submitted at this conference.
In order to enable rational comparisons between such different
reentry techniques, a commonset of ground rules, requirements, and
objectives for Phase Alpha only was established. The significant
requirements are shownin table I.
Piloted meansthe maximumuse of the manto reduce subsystem com-
plexity. A single crew memberis used to reduce weight and cost. One
thousand pounds of research-equipment payload does not include weight
of structure, auxiliary power, and cooling to support the 1,O00 pounds
of payload. If those were included, the total would exceed 2,000 pounds.
The 79-cubic-foot volume, combinedwith the large payload weight, allows
flight tests of almost any military or scientific subsystem desired.
"Once-around" operating capability meansthat the design shall be capable
of Step IIA orbital operation although Step I reaches only about
19,000 ft/sec.
"Safe" boost meansthe boost trajectory shall not penetrate the
recovery ceiling. The recovery ceiling is that altitude-velocity con-
dition at 7 = O, from which the unpoweredvehicle can just pull back
into equilibrium glide without exceeding its temperature or load limits.
The requirement for landing within lO square miles was established
to avoid continued expensive marine recovery operations. This area was
chosen to permit the use of military airports; thus trees and hills
would not interfere with parachute landings. Consistent subsystems
(and also consistent ground-support equipment) were used where logical to
prevent differences in vehicle weight resulting only from different
levels of refinement in subsystem design. Reusability for four flights(with refurbishment) was a contractual requirement.
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The requirement for at least neutral static stability during first-
stage boost and reentry was established to provide better safety. During
second-stage boost, the divergence rate is low enough to allow reasonable
escape. Escape provisions were not required, but a requirement for
safety approaching lO0 percent led the designers to use escape systems.
Ballistic reentry devices generally needed escape only during first-stage
boost. The 6,000-foot margin above the critical heating limit requires
that the vehicle not approach its structural limit too closely. This
statement is only applicable for gliders; a similar rule was used for
ballistic shapes.
Certain other ground rules have been used both prior to and during
Phase Alpha._ These include structural factors of 1.4 on booster tanks
and 1.9 on the remaining structure and a conservative heating assumption
which requires the structure to withstand heating rates for either
laminar, turbulent, or transition flow, whichever is worst.
None of the preceding ground rules are considered firm for the
remainder of the Dyna-Soar program. Certain of these are being reeval-
uated now; the requirement for neutral static stability throughout the
entire first-stage boost may be changed to require stability only at
first-stage burnout. This will permit a coast period between stages one
and two.
Certain items which were used as ground rules during earlier design
efforts were abandoned as ground rules during Phase Alpha but were main-
tained as dependent variables, and the designs were compared with respect
to these variables. Examples of these include the amount of lateral maneu-
verability, ability to land conventionally, ability to gather research
data, and potential for eventual military use.
Certain terms have been used in this paper which need additional
clarification. Figure 1 shows a typical variation of altitude h with
velocity v for a glider. This plot can be used to define some of the
less familiar terms of this paper and of subsequent papers.
The equilibrium glide lines for CL, MAX and (L/D)MAX are shown in
figure 1. These lines bound the normal flight regime. Flight at a CL
less than that for (L/D)MAX is possible but not desirable. When the
glider is banked to approximately 45 ° and flown at the CL for (L/D)MAX ,
the largest lateral range is attained. The glider seeks an equilibrium
line at a somewhat lower altitude due to the bank angle.
The temperature limit line shown in the figure is actually a com-
posite limit for either the nose, leading edge, or bottom surface
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depending upon the angle of attack. The q limit represents a
dynamic pressure of _00 lb/sq ft during reentry. At this pressure
the elevon surface actuator is load-limited. Under certain flight con-
ditions, a load factor of 7-33 is limiting instead.
The distance shownas the flight corridor is a measure of the
research ability of the glider. The 6,000-foot margin has been pre-
viously mentioned and is graphically described on the figure. The
recovery ceiling is shownonly in its approximate location. A glider
inserted without power at that ceiling has insufficient velocity to
maintain equilibrium flight at that altitude and hence falls. By
pulling maximumlift, the aircraft can just barely arrest the fall
before encountering the temperature or structural limit.
In conclusion, the technical effort during and prior to Phase
Alpha has formed a solid foundation for the remainder of the Dyna-Soar
program.
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TABLE _ I
GROUND RULES
• PILOTED(ONE CREWMAN)
• I,OOO-POUNDS RESEARCH EQUIPMENT
• 75 CUBIC FEET VOLUME FOR EQUIPMENT
• ONCE-AROUND OPERATING CAPABILITY
• "SAFE" BOOST
• LAND WITHIN I0 SQUARE MILES
• CONSISTENT SUBSYSTEMS
• REUSABLE FOR FOUR FLIGHTS
• AT LEAST NEUTRAL STABILITY
• ESCAPE PROVISIONS
• 6,000-FOOT MARGIN WITH CRITICAL HEATING
ILL
h
TYPICAL REENTRY CORRIDOR
RECOVERY CEILING_ J
_,_.19%_ T E M P.
/;//_ " _-cj LiMiT
Figure 1


Introduction to Boeing papers on Dyna-Soar project

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