The concept is summarized of a diffusive burning supersonic combustion ramjet engine (scramjet) envisioned by Antonio Ferri and some of the salient technologies are highlighted as developed by General Applied Science Labs, PIBAL, and NYU, under his direction

Erdos, John I.

Nucci, Louis M.

English

NASA Technical Reports Server

N92-21519
PIONEERING SCRAM JET DEVELOPMENTS BY ANTONIO FERRI
John I. Erdos and Louis M. Nucci
General Appfied Science Laboratories, Inc. (GASL)
Ronkonkoma, New York 11779
PROLOGUE
"I would like to make the following statement: The existing technological ability and
• scientific background accumulated in many years of work will be lost if a small but
continuing effort in this field is not maintained. Resumption of work in air-breathing
,,, engines at a later date would require a much larger effort."
• Antonio Ferri, 1960, "Possible Directions of Future Research in Air-Breathing Engines,"
AGARD Combustion and Propulsion Colloquium, Pergamon Press Ltd., London, England.
"We now have 5000 people working on the National Aero-Space Plane program"
Robert Banhelemy, 1990, address to participants in the 8th Semi-annual NASP Technology
Symposium, Monterey, California.
INTRODUCTION
This presentation summarizes the concept of a diffusive burning supersonic
combustion ramjet engine (scramjet) envisioned by Antonio Ferri and highlights some of the
• salient technologies developed at GASL, PIBAL and NYU under his direction.
Although true paternivy of the scramjet engine may never be conclusively determined,
it is clear from the published literature that the concept of a ramjet engine that burned the
fuel in an alrstream which entered the combustor supersonically occurred more-or-less
independently to a small group of researchers between 1947 (References 1 and 2) and 1960
(References 3 and 4). Two approaches were envisioned: one used a detonation wave to
burn the fuel and the other, first proposed by Ferri, used a diffusive (i.e. mixing controlled)
process that was (ideally) shock-free. The subsonic burning ramjet, the supersonic
detonative-burning scramjet and the diffusive-burning scramjet are compared schematically
in Figure 1. The detonation wave engine concept is clearly first attributable to Maurice Roy
(Reference 1) but the recorded discussion following his 1959 paper indicates that the first
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https://ntrs.nasa.gov/search.jsp?R=19920012276 2020-03-17T13:10:52+00:00Z
experimental demonstrations were carried out in u.s. industrial and university research labs
in the late 1950's, and that Ferri's experimental achievement of diffusive supersonic
combustion carried out at the same time, also in the U.S., was, at very least, the first such
demonstration having development of an orbit-capable aircraft engine as its goal (Reference
5). Inclusion of the diffusive-burning supersonic combustion ramjet in a "composite" (i.e.
multi-stage) system was also envisioned from inception of the engine concept (Reference
6).
Ferri conducted most of h/s basic scramjet research activities in the Aerospace
Laboratories he built at the Polytechnic .Institute of Brooklyn (PIBAL) and later at New
York University (NYU), and directed the technology development, systems development and
application studies employing the resulting technology to supersonic and hypersonic cruise
and orbit-capable aircraft at General Applied Science Laboratories, Inc. (GASL). The first
serious attempt to design and build a SSTO aircraft employing a composite turbojet, ramjet,
scramjet and rocket system was conducted in cooperation with Republic Aviation, as pan
of the Air Force's original Aero-Space Plane project. As descn'bed in the Republic Aviation
News issue of September 9, 1960, the aircraft would employ four hydrogen-fuelled J-58 type
turbojet engines and four ramjet engines that transitioned to supersonic combustion for the
Mach? to 25 range, have a gross rake-off weight of 400,000 lbs and a payload of 20,000 lb.
The Air Force program was terminated about five years later, and while none of the
competing aircraft designs could achieve the SSTO objective, it is generally agreed that the
Republic design with its heavy dependence on airbreathing propulsion to orbit was the most
promising. Concurrently with the Aero-Space Plane program, the Air Force sponsored
several scramjet engine development programs. An Air Force press release dated
November 12, 1964, announced the "first successful demonstration of internal fl_,'ust from
a scramjet engine." 'The tests were conducted at General Applied Science Laboratories,
Inc. Westbury, New York, under the supervision of Dr. Antonio Ferri, GASL President."
TECHNICAL HIGHLIGHTS
"From an operational point of view, the ideal vehicle for space investigations is
probably a vehicle that is able to take off as an airplane with low accelerations, can
accelerate gradually to orbital speed along a trajectory that can be controlled in time and
position, can carry a large payload, and can re-enter, land, and be used again for successive
missions." With those introductory remarks, Ferri went on to descn'be a preliminary study
of such an orbit-capable aircraft in Reference 3. He proposed use of hydrogen-burning
turbojet engines to accelerate from take-off to Mach 3, followed by ramjet engines to "high
Mach numbers" (around 8 to I0) and then diffusive burning scramjets to orbit. He
dismissed use of detonative combustion due to the variable geometry requirements. Indeed,
he recognized that the specific impulse 0sp) advantage of the ramjet/scramjet could be
easily offset by the weight of a variable geometry inlet system. The desire to achieve the
required inlet starting characteristics at low supersonic Mach numbers and the required
compression at high Mach numbers with a fixed geometry engine became the hallmark of
Ferri's scramjet work. Toward this end, his inlet designs became characteristically flu'ce-
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dimensionaland employedtheconceptof "thermal compression" to achieve the goal of fixed
geometry.
Without regard to the details of the design, the first paper presented a series of
scramjet engine parameters and performance characteristics that varied relatively little in
subsequent studies. What did change is the depth of the technology base and design effort
to support the performance estimates. The original vehicle layout is shown in Figure 2,
together with the weight and payload. Ferri noted that a doubling of structural weight
would triple the take-off weight, perhaps more closely resembling the Republic design. The
key engine design parameter is the combustor inlet Mach number, which is shown in Figure
3. Further details of the inlet and combustor were presented in later papers. The initial
estimates of specific impulse in the scramjet mode from this study are presented in Figure
• 4. Ferri's aircraft design also placed more emphasis on maximizing the inlet capture area
than the Republic design. The figure of 100 sq.ft, of inlet stream tube capture area pertains
to Figure 5, which shows the engine thrust levels. Estimates of thrust minus drag then
yielded the acceleration potential shown in Figure 6.
A concerted effort to provide the technology base for these performance estimates
then followed at PIBAL (Reference 7). Notable accomplishments included the development
of pioneering CF_ capabilities based on the Method of Characteristics and Parabolized
Thin-Layer Navier Stokes solvers with coupled finite-rate chemical reactions, experimental
surveys of supersonic hydrogen-air mixing layers and comparisons with theory to "tune" the
postulated eddy viscosity models, and conduct of diffusive supersonic combustion
experiments with direct and schlieren flow visualization.
In a coordinated effort at GASL, Ferri directed the construction of a combustion-
driven shock tunnel in which the first measurements of supersonic combustion of hydrogen
in a pulse type test facility were made. These measurements became the basis for the first
correlation of ignition delay time for hydrogen-air mixtures at representative scramjet
conditions. He also built a hydrogen combustion heated vitiated air wind tunnel with Mach
3 to 8 simulation capabilities to test ramjet and scramjet engine concepts, which is still in
daily use.
The results of these technology development studies as well as updated system studies
were summarized in Ferri's 1964 Lanchester Memorial Lecture (Reference 8) and in an
AIAA survey article (Reference 9). Of interest is the capture area schedule and total
pressure recovery calculated for a fixed geometry inlet in the Mach 4 to 24 range shown in
Figure 7. The inlet design is "similar to that" of Reference 3. Spillage drag and skin friction
drag were included in the calculated performance shown in Figure 8. It was also pointed
out in this paper that a fairly low trajectory must be flown to have sufficient air capture rate
and dynamic pressure to be able to obtain an adequate thrust margin for acceleration,
indicated in Figure 9 as the "acceleration corridor." Associated with the high dynamic
pressure is a high heat transfer rate and consequently a high temperature (2000°R) for the
hydrogen fuel being used as a regenerative coolant for the structure. On the positive side,
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a significant arno_t of thrust is derived from _pandi_ the hot hydrogen to supersonic
axial velocity through the fuel injectors. On the other hand, at some suborbital speed
(depending on the trajectory and the vehicle design) the fuel flow rate required to cool the
structure begins to exceed the stoichiometric rate required for acceleration. In Ferri's
design, this occurred at about Mach 22, as shown in Figure I0, with the inlet and nozzle
surfaces being the primary conm'butors to the cooling problem. Performance trade-offs
associated with fuel-air equivalence ratio and other engine component parameters are
discussed in the paper. Although the quantitative results for engine performance may not
be consistent with current technology, all the basic aerophysics and engine design
considerations discussed in this paper are still pertinent today.
While not explicitly covered in this presentatio_ the subject of thermal compression
is well worth noting. The basic concept was to use the addition of fuel mass and the
concomitant release of heat to accomplish a portion of the inlet compression process, in
- preference to variable inlet contraction. The fluidic control system should be substantially
lighter than mechanical systems for geometric variations of the inlet surfaces. The concept
was originally tested at relatively low supersonic Mach numbers where the low momentum
of the fuel and large pressure increases associated with combustion conspired to make
control difficult. However, at the higher (hypersonic) Mach numbers where scramjet
combustor tests are currently being conducted in pulse facilities, the occurrence of thermal
compression is frequently evident in the data, and the conditions are far more favorable to
its exploitation.
EPILOGUE
Ferri's last review of scramjet technology was presented at the AIAA Third Annual
Meeting in 1966 (Reference I0). He left GASL in 1967, and in 1968 moved from PUB to
NYU. He continued his research efforts in scramjet combustion at NYU under NASA
sponsorship. In 1972, Ferri and a group of colleagues rejoined GASL. Unfortunately, he
died of a heart attack in 1975, about a decade before the current resurgence of interest in
scramjet engines and SSTO aircraft began. His close colleague, Mr. Ernest Sanlorenzo, who
joined Ferri (and the second author) at GASL in 1956, devoted a large part of his career
to pursuing scramjet technology, and was originally scheduled to give this presentation, also
died of a heart attack in January 1992, while managing the NASP ramjet/scramjet tests at
GASL. The remaining "corporate memory" of Ferri's ideas for the design of scramjet
engines, not reported in the literature but conveyed through lively technical discussions,
resides with three people at GASL (besides the authors) and a few people scattered
throughout the aerospace community.
REFERENCES
(1) Roy, M., "Thermodynamique des Systemees Propulsifs a Reaction," DUNOD, Pari_
France, 1947.
3-4
(2)
O)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
Roy, M., "Propulsion Supersonique par Turboreacteurs et par Statoreacteurs," Proc.
First International Congress of the Aeronautical Sciences (ICAS), Madrid, Spain, 8-
13 September 1958.
Ferri, A. "Possible Directions of Future Research in Air-Breathing Engines," Fourth
AGARD Combustion and Propulsion Colloquium, Pergamon Press Ltd, London,
England, pp. 16-36, 1960.
Dugger, G. L, "Comparisons of Hypersonic Ramjet Engines with Subsonic and
Supersonic Combustion," lbid, pp. 84-119.
Fen'i, A., Daskin" W., Feldman" L and Nucci, L, "The Launching of Space Vehicles
by Air-Breathing Lifting Stages," in Vistas in Astronautics, Vol If, Pergamon Press
Ltd, London, England, 1959.
Nucci, LM., and Zipkin, M. A., "Composite Air-Breathing Systems," Ibid, pp. 16-36.
Fen'i, A., Libby, P. A., and Zakkay, V.,Wheoretical and Experimental Investigation
of Supersonic Combustion," Proc. Third ICAS, Stockholm, Sweden, 27-31 August
1962. Also available as PIBAL Report 713, AD 291-712, September 1962.
Ferri, A., "Review of Problems in Application of Supersonic Combustion," Journal
of the Royal Aeronautical Society, Vol 68, No.645, September 1964.
Ferri, A., "Supersonic Combustion Progress," Astronautics and Aerospace
Engineering, August 1964.
Fen'i, A., "Review of Scramjet Propulsion Technology," AIAA Paper No. 66-826, 29
November - 2 December, 1966.
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f
Subsonic burning.
Supersonic burning with detonztion shock.
Supersonic burning with diffusion time.
Figure 1. Schematic Representations of
Subsonic Burning Ramjet,
Detonative Burning Scramjet and
Diffusive Burning Scram jet
Aerod)'n_mic i_ut for =/O'ptrsonic ramjtt 8irtraft
Table J
Initial weight 130,000 lb
Empry weight m orbit 50,000 lb
Payload in orbit 10,000 Ib
Figure 2. Perspective Drawings of
Ferri's 1960 Air-Breathing
SSTO Aircraft and
Estimated Weights
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I0
?
8 m
.'_ G-
5
¢
&
t ! ! I
JS 2D 2S _O
Fret Sl_eom V.Qch NO
Figure 3.
Rn_njctb,.o'n._,bdtt M_A mnnb_
Scramjet Combustor Entrance
Mach Number Schedule
(1960)
3ZOC
=sooI
._ 2CCC --
.Y.
_C,O.
.oi!
Frtt $.'re._ MCch I_c
Romje_specificimpulse-',_thsuptrson:.cbu_ir.! _:,.d,o_e,:.fud
Figure 4. H2-fuelled Scramjet
Specific Impulse Estimates
(1960)
3-7
t,-
,#
OODOOrw
ZOOOOOt,
Free $treom Moth NO-
Ramjet lkrust ,,,i_hsupersonicburninJr;./'retJlrtarncaplvrtaria } OOJ'F ; hvdrof,enfar!
Figure 5. H 2-fuelled Scram jet
Thrust Estimates (1960)
ic
oe
cP
-_" Or=
O.C!
"_' OZ
..f
I I I !
0OO IC.OOO _.._..CO 2:_.r.,¢O 25.CC0
F_;_ wlo_ty, f t/se.:.
T.rplcala.,!,rat;on capabilito'.fora hO_trsonicTan,jttalrcra_
Figure 6. Acceleration Capability
of Ferri's 1960 SSTO
Aircraft
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INITIAL CONDITIONS FOR
FIXED-GEOMETRYENGINE
A=/Ao' (burner entrance inlet areas) ,,= 0.02.
A. Inlet performance.
:'° r /'7 I I I
= / Capture.area ratio (A,,//_')
i
_ Stagnation pressure recovery _1
o.2f I t . I (P"(_")-!
o lll I
4 B 12 16 20 24
FLIGHT MACH NUMBER
Figure 7. Performance of Ferri's
Fixed Geometry Inlet (1964)
ENGINE PEI1FORMANCE FOIl RXED-GEOMETRY ENGINE
Ae/,ko' (burner entrance afea/inJel: area) == 0.02;
nozzle exit area/inlet area == 1.Z; P=. == free-stream pressure.
24
2¢
==
¢D
z IE
z
u
,K
v- 18
x
8
4
D
ir specific intpuise
I
\
\
\
specific impulse
\
40 BO 120 i000 2000 3000 4000
I., SEC le. $1rC
L--
I
L_
IL-
i
I
L--
20 30 40
T/P== Ao'
Figure 8. Performance of Ferri's Fixed Geometry
Scram jet Engine (1964)
3-9
,4OOO
ool....1
0 -_ /0 /5 20 @5 .._
VELOCITY,1000FT/SEC
Figure 9. Comparison of Ferri's "Acceleration Corridor"
with Gazley's "Continuous Flight Corridor"
,2
_.= 0.8
-_
_z 0.4
0.2
0
4 6
, i/I
' iI
BURN_j_" . __
_L
Figure 10. Cooling Requirements for
H2-fuelled Scram jet Powered
SSTO Aircraft (1964)
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Pioneering scramjet developments by Antonio Ferri

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