INTRODUCTION

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP81B00879R001000150001-8
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 31
• Document Creation Date: December 23, 2016
• Document Release Date: May 2, 2014
• Sequence Number: 1
• Content Type: REPORT

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TABLE OF CONTENTS
Page No.,
Figure Index
ii
INTRODUCTION
1
DESIGN AIMS
2
DESCRIPTION OF AIRCRAFT
3
POWER PLANTS
4
EQUIPMENT
8
COCKPIT
9
LANDING GEAR
11
CONSTRUCTION MATERIAL
12
CONTROLS
13
FUEL TYPES
14
MISSION CAPABILITIES
18
RADAR CROSS SECTION
19
WEIGHT CONTROL
21
PERFORMANCE
23
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.t-'age ii
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FIGURE INDEX
No.
Title
Page No.,
1
Basic Dimension Drawing
5
2
Variation of Engine Thrust vs. Altitude
6
3
Basic Mission - JP-150 Fuel
15
4
The "Buddy" Mission - JP-150 Fuel
16
5
Mission on High Energy Fuel
17
6
Weight Breakdown
22
7
Performance Summary
24
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SP-108
INTRODUCTION
This report presents a study of a lightweight reconnaissance
aircraft designed for flight at very high altitude and speed. Previous
studies on larger aircraft known as Archangel I and II resulted in types
having a gross weight of 100,000 pounds to 135,000 pounds, which were
considered too large for the purpose intended.
The small aircraft described in this study (and called A-3
hereafter) has a gross weight of approximately 32,000 pounds. Its con-
struction at this weight calls for extreme weight control and ingenuity of
design in order to obtain satisfactory performance and range.
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ivo
DESIGN AIMS
The conception of the aircraft included the following major
considerations:
I. The aircraft had to be a 'self-contained" unit, requiring
no launching assistance from other aircraft.
2. The turbojet engines used must be an adaptation of a type
already in existence.
3. The fuel used initially should be of a petroleum type not
requiring large new facilities for its production.
4. The aircraft should be capable of exploiting the more ad-
vanced boron fuels.
5. The radar cross section of the aircraft should be minimized
In every way feasible.
6. The minimum initial cruise altitude should not be less than
90,000 feet. Target altitude should be 95,000 feet or more.
7. Radius of action, including a 1800 turn, should be no less
than 1500 nautical miles at a cruising speed of M 3. 0 to
3. 2 on petroleum fuel. With borane fuels, the radius should
be approximately 2000 nautical miles at the same or higher
altitude and speed.
8. The minimum weight and cost should be achieved for the
system.
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SP-108
DESCRIPTION OF AIRCRAFT
The A-3 aircraft has a wing area of 500 square feet, span of
33.6 feet and length of 62.5 feet.
/t is powered by two afterburning Pratt and Whitney JT-12
engines assisted by two 40-inch diameter, ram-jets. The turbojets are
located above the wing, which is shaped around the bottom of the engines
to reduce the frontal area. The ram-jets are located on the tips of the wing.
Figure 1 shows the general arrangement of the aircraft.
The nose of the aircraft holds the equipment bay, cockpit and
nose gear. Aft of the cockpit, the whole fuselage contains a series of
integral fuel tanks until the tail structure is reached. The 3 percent thick
wing also holds fuel which is burned in climb to avoid high temperature
effects at high speeds. Each ram-jet carries 1100 pounds of fuel in its
center section. This fuel is the first to be used.
The use of a horizontal tail is subject to wind tunnel tests. It
Is desirable to delete it from a radar cross section point of view, if pos-
sible. An alternative design incorporating a horizontal tail is being carried
forward, in case stability and drag tests show it to be necessary.
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SP-108
POWER PLANTS
The turbojet power plants used are two Pratt & Whitney JT-12
engines having a take-off sea level rating of 4,000 pounds. Afterburners
are used on the engines, and it is necessary to provide for Mach 3. 2 oper-
ation by material changes at several points in the engine. We have been
told that major aerodynamic design changes are not required. The basic
JT-12 engines have run and passed an unofficial 50-hour test at their cur-
rent design rating. Discussions with the engine manufacturer indicate that
the adaption of the engine to the A-3 is not considered to be a difficult task.
This engine was chosen because it has an excellent thrust/weight ratio and
a low compression ratio, which adapt it to high speed. Figure 2 shows the
thrust variations with altitude used in this report, based on data received
from Pratt & Whitney.
The tip ram-jets have been studied based on data from
Marquardt and Pratt & Whitney, and thrust output is also shown in Figure
2. It will be seen that at high altitude the ram-jets provide by far the
major portion of the required thrust. The specific fuel consumption of the
ram-jets is as good as, or better than, that of the turbojet engines, when
operating above Mach 3.0. Final figures on the weight breakdown are not
available but are believed to be about 600 pounds to 800 pounds each, which
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SP-108
POWER PLANTS
The turbojet power plants used are two Pratt & Whitney JT-12
engines having a take-off sea level rating of 4,000 pounds. Afterburners
are used on the engines, and it is necessary to provide for Mach 3. 2 oper-
ation by material changes at several points in the engine. We have been
told that major aerodynamic design changes are not required. The basic
JT-12 engines have run and passed an unofficial 50-hour test at their cur-
rent design rating. Discussions with the engine manufacturer indicate that
the adaption of the engine to the A-3 is not considered to be a difficult task.
This engine was chosen because it has an excellent thrust/weight ratio and
a low compression ratio, which adapt it to high speed. Figure 2 shows the
thrust variations with altitude used in this report, based on data received
from Pratt & Whitney.
The tip ram-jets have been studied based on data from
Marquardt and Pratt & Whitney, and thrust output is also shown in Figure
2. It will be seen that at high altitude the ram-jets provide by far the
major portion of the required thrust. The specific fuel consumption of the
ram-jets is as good as, or better than, that of the turbojet engines, when
operating above Mach 3.0. Final figures on the weight breakdown are not
available but are believed to be about 600 pounds to 800 pounds each, which
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STAT
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is substantially the same as the turbojets. The ram-jets are configured
to include provisions for carrying WO pounds of fuel as a tip tank during
the early part of the climb. It may be necessary to fair over the aft end
of the ram-jet, using a Mylar pressurized sack, to reduce the drag in
climb. For operation between Mach 1. 0 and 1. 6, it will probably be neces-
sary to use a hood in conjunction with a movable spike on the nose of the
ram-jet to obtain optimum thrust. Such hoods have been used on test ram-
jets in the past.
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SP-108
EQUIPMENT
The equipment volume provided for the reconnaissance gear
is less than that used in the U-2 aircraft. It is assumed that re-packaging
can lighten the gear and reduce its size. The weight of the reconnaissance
gear, the pilot and his equipment has been set at a total of 500 pounds.
Under normal conditions, this would leave between 250 and 300 pounds for
the equipment. The problems of temperature control in the equipment bay,
the rate of heat conduction, and the effect of a turbulent boundary layer at
high Mach number on photography have not yet been investigated.
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eage
SP-108
COCKPIT
The cockpit dimensions have been reduced from the U-2 in
the interests of reducing aircraft drag. It should be borne in mind that
the mission time for this aircraft is approximately one-fifth of that for the
U-2, so reduced room for the pilot is in Order, The number of instruments
has been reduced to the minimum, because of space and weight consider-
ations. Their places have been taken by warning lights, when feasible.
The rate of climb instrument has been totally deleted, as the very high
performance of the airplane would keep it at an extremely high reading
at practically all times, and it is not considered necessary for blind flight,
as the aircraft is not intended to hold in a normal type of traffic pattern
for any important length of time.
It is necessary to redesign such standard items as control
sticks, rudder pedals, brake valves, etc., in order to save weight. Behind
the pilot's seat are located a number of the aircraft system complements.
These must be kept in a cooled and pressurized area for satisfactory oper-
ation at altitude. The pilot's seat will be a rocket type designed for escape
at zero velocity, as well as for the flight conditions during training and
ferrying flights. It will be replaced with a lightweight seat for the tactical
missions.
It is intended that the pilot use an adaptation of the Navy full
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SP-108
pressure suit, rather than the present Air Force partial pressure suit.
The great advantages of being able to cool and ventilate the pilot separate-
ly from the cockpit itself, the lack of shock from high altitude decompres-
sion, and the greater mobility when pressurized make this suit a desirable
improvement.
The cockpit pressurization is intended to be by nitrogen bottles
for high altitude, with standby air bleed pressurization at low altitudes.
Cooling of the cockpit and possibly the equipment bay will most likely be
done by water boil-off from a radiator type construction built directly into
the fuselage skin.
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SP-108
LANDING GEAR
The landing gear is a lightweight type designed to U-2 criteria,
but a normal tricycle gear geometry, with regards to the CG position, is
used in the fore and aft vertical plane of the aircraft. Tip pogos for lateral
stabilization will be used on take-off and dropped, as on the U-2. The
problem of lateral control on landing should be much less than with the U-2
aircraft, and there is a good possibility that enough stability can be obtained
with the main gear that the airplane could be balanced down to very low
velocities without tipping over on the ram-jets. The question of wheel
braking for a rejected take-off is not yet solved. It is not desired to carry
the conventional amount of brake steel to absorb the required amount of
energy. The best solution is probably to lock the main gear wheels in such
an emergency, blow the tires, and skid along on the wheels themselves. An
alternative to this would be a simple anchor chain type of barrier.
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SP-108
CONSTRUCTION MATERIAL
The aircraft is constructed mainly of high strength titanium
alloy. Light gauges down to .010 inches will be used, but the most probable
minimum gauges in stressed areas will be .016 inches. Using such
material requires a large number of supporting elements, which add to the
tooling and material costs. The wing construction is such that the beams
(not the wing skins) run through the fuselage tanks. Their strength helps
maintain fuselage shape when the fuel is pressurized for altitude operatio?n.
This type of construction requires building a section of the fuselage as an
integral part of the wing. It is the lightest conceivable design for this
particular aircraft concept.
It is not planned to insulate the wing or fuselage fuel sections,
as current indications are that the mission would be completed prior to
heating up the fuel beyond 250?F, which is an acceptable value for the
engines. It may be necessary to keep reserve fuel in a small insulated
tank, however.
It is not planned at this time to build any large elements of the
aircraft from plastic. If particular problems show up radar-wise, such
items as inlets to the engines, and possibly a vertical tail, would be studied
for whatever reduction in cross section could be obtained.
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eage 1.5
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CONTROLS
The aircraft is flown by powered controls. The trailing edge
of the wing acts both as elevators and ailerons. It is necessary to use a
power rudder to provide ample directional control should a ram-jet blow
out at high speed. Directional control is ample to restrict the aircraft to
less than 3? angle under this condition.
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SP-108
FUEL TYPES
Several different fuels have been studied for the turbojets and
the ram-jets. It is proposed that the initial operation start with JP-150,
a petroleum-based fuel of reasonable availability and cost.
The following table compares JP-150 to decalin:
Decalin JP-150
Heating value/pound 18.400 19, 100
Specific Gravity .872 . 733
Cost/Gallon $2. 60 $0.55
Burning Characteristics Same as Same as
JP-4 JP-4
It will be seen from the table that the use of JP-150, at its lower specific
gravity, penalizes the aircraft volume by about 14 percent. This, however,
provides stretch in the aircraft design for obtaining greater range with
heavier fuels, such as HEF-3, at a later date. The use of the borane fuels
would provide from 15 to 30 percent more radius of operation at a given
weight. However, because of their better burning characteristics, there
may also be an improvement in power at altitude, which would allow the
use of more total fuel and thereby give it a further gain in range. Figures
3, 4, and 5 show various mission capabilities.
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SP-108
MISSION CAPABILITIES
Using JP-150 fuel (similar to JP-4), take-off is made on turbo-
jet power at a gross weight of 32,000 pounds.
25,000 feet at a speed of 400 ,knots E. A. S. At
The aircraft is climbed to
this altitude, the ram-jets
are ignited to assist in climb. Using a constant indicated airspeed, climb
is continued to 75,000 feet, where Mach 3.2 is reached. This speed is
held and climb continued to 90,000 feet. At this height, the fuel/air ratio
of the ram-jets is reduced and cruising flight ensues. A target altitude of
95,000 feet is reached, where a 1800 turn is made. Returning to base,
higher altitudes are reached.
The advisability of refueling the A-3 from a U-2 aircraft was
studied. This did not improve the A-3 penetration capabilities, as it was
assumed that all refueling was done prior to penetration. The added distance
on the return leg, therefore, reduced the penetration. The situation is
different if the aircraft could be refueled at altitude from another A-3. It
is assumed that this could be done at any point on its basic mission. Figure
4 shows the gain obtainable in actual combat radius for the "Buddy" mission.
The use of HEF provides the best capability for the A-3, considering all
factors.
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STAT
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SP-108
WEIGHT CONTROL
A breakdown of the aircraft weight elements is shown on
Figure 6. These weights are predicated upon most extreme weight control
procedures, including many static tests run both at normal and elevated
temperatures. The adiabatic temperature rise for the speed is roughly
?
875?F, resulting in actual temperatures of roughly 800?F inside of ducts
and certain other stagnation areas. By making proper treatment to ob-
tain maximum emissivity, skin temperatures can probably be held to values
between 300 and 500?F. There must be few or no compromises made for
weight, because the power of the turbojets to accelerate the aircraft to a
speed where the ram-jets can be lighted is critical. Should the wind tun-
nel tests show more favorable transonic drag characteristics than expected,
there could be some relaxation in providing more weight for the equipment
and aircraft systems.
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STAT
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1"-C1.15C LC.
WEIGHT ESTIMATE
/ -
WING 2, 715
VERTICAL 7375
FUSELAGE 1, 780-'
LANDING GEAR /375'
SURFACE CONTROLS 4/450
JT -12 DUCTS & FAIRING /605
JT-I2 ENGINES 1,685
RAM JETS /1,600
ENGINE CONTROLS /80
FUEL SYSTEM I?05
INSTRUMENTS
HYDRAULICS V'
ELECTRICS
ELECTRONICS
FURNISHINGS
AIR CONDITIONING
WEIGHT EMPTY
OXYGEN
OIL
UNUSABLE FUEL
PILOT
PAYLOAD
ZERO FUEL
WING FUEL
/120
450
11,340
407
207'
( 100%7
28/
215'
12, 000
, 12-0
FUSELAGE FUEL 14, 880
TAKE-OFF WEIGHT \s? 30, 000?
i
(Ramjets carry 1,400 lb each in addition to above)
SP-108
Fig. 6
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SP-108
PERFORMANCE
Figure 7 shows a summary of the aircraft performance. It
will be noted that rather excellent performance is available, even at take-
off weight, on the turbojets alone. Peak performance is obtained at
75,000 feet, where a Mach number of 3.2 is reached at a rate of climb of
76,000 feet per minute.
The aircraft is designed to use a400 knot E.A. S. For design
safety purposes, a margin of about 30 knots would be provided over this
figure. Limitations on the rolling velocity would have to be accepted at
this speed, however. The aircraft can make a 180? turn at target weight
and altitude of 55 miles radius. Because of the ability to richen the
fuel/air ratio, this turn can be made without loss of altitude.
It should also be pointed out that at a sacrifice of range, higher
penetration and cruising altitudes can be obtained, by increasing the power
output from the ram-jets by the same means.
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