project silver bug

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 CUFONSM gratefully acknowledges Mr. James Hartman of Griffith IN who originally called our attention to Project Silver Bug long before the many copies of this report now available appeared on the internet.


[ FOIA reply letter: ]
DEPARTMENT OF THE AIR FORCE
AIR INTELLIGENCE AGENCY
6 Mar 98
NAIC/SCVMS (FOIA)
4180 Watson Way
Wright-Patterson AFB  OH  454-5648
Dale Goudie
[address removed by CUFONSM]
Dear Mr. Goudie
This letter is in reference to your Freedom of Information Act (FOIA) request dated 15 Feb 98 
for a copy of Project Silver Bug.  We received your request and assigned FOIA case number
NAIC-98-046 to it.  Please reference this case number when  inquiring about this request.
After reviewing the document, it was determined that it is releasable.
Your request was processed in the all other category.  The document we are providing contains 
 30 pages.  All fees have been waived.
Sincerely
/s/ Gery D. Huelsman
Gery D. Huelsman, Msgt, USAF
Chief, F Freedom of Information Act
Information Management Operations
Attachment
Project Silver Bug
                   Golden Legacy, Boundless Future... Your Nation's Air Force

TECHNICAL REPORT TR-AC-47 (Unclassified)
JOINT ATIC-WADC REPORT ON
PROJECT SILVER BUG
PROJECT NO. 9961
15 FEBRUARY 1955
AIR TECHNICAL INTELLIGENCE CENTER
WRIGHT-PATTERSON AIR FORCE BASE
OHIO

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UNCLASSIFIED
1. Information conflicting with or permanently affecting
that contained in this publication should be forwarded by the
recipient directly to:
Commander
Air Technical Intelligence Center
Wright-Patterson Air Force Base, Ohio
This in no way abrogates or alters responsibility for sending
such information or any pertinent intelligence data through
already established intelligence collection channels of the
various services or agencies of the U.S. government.
2. WARNING:  This document contains information af-
ecting the national defense of the United States within the 
meaning of the Espionage Law, Title 18, U.S.C., Sections 793
and 794.  Its transmission or the revelation of its contents in
any manner to an unauthorized person is prohibited by law.
UNCLASSIFIED
AF-WP-O-21  APRIL  54   16M

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TECHNICAL REPORT NO.  TR-AC-47
(Unclassified)
JOINT ATIC-WADC REPORT ON
PROJECT SILVER BUG
PROJECT NO. 9961
15 FEBRUARY 1955
Published by
AIR TECHNICAL INTELLIGENCE CENTER
WRIGHT-PATTERSON AIR FORCE BASE
OHIO
No copyright material is contained in this publication.   T55-2049
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TABLE OF CONTENTS
                                                                                                                          Page No.
Summary  iii
Section I Characteristics   i
A. Background
B. Description of the Proposed Aircraft
C. Performance
  1
  1
17
Section II USAF Research and Development Status 23
A. Principal Problem Areas
B. Present Development Status
23
23

LIST OF ILLUSTRATIONS

Figure 1 Three-view General Arrangement of Proposed Multi-engine Research Aircraft   2
Figure 2 Cut Away of Research Aircraft   3
Figure 3 Three-view General Arrangement of Research Aircraft   5
Figure 4 Section Cutaway of Research Aircraft   6
Figure 5 Ground Cushion Effect   7
Figure 6 Airflow Into Intake During Take-off and Landing 11
Figure 7 Section of Airflow Pattern for Take-off 12
Figure 8 Typical Section of Exhaustor Duct Showing Take-off Gas Flow 13
Figure 9 Section Through Rear of Aircraft at Supersonic 14
Figure 10 Typical Cross-Section Through Engine 15
Figure 11 Through Flow at Low Forward Speed 16
Figure 12 Cross-Section Showing Bearing Airflow 18
Figure 13 Perspective View Showing True Path of Bearing Air 19
Figure 14 Exhaust Jet Angles at Low Forward Speed 20
Figure 15 Conanda Effect: High Aspect Ratio Jet Bending 21

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TABLE OF CONTENTS (Cont)
                                                                                                                           Page No.
Table I Physical Characteristics   5
Table II. Weight Breakdown   9
Table III. Contractor Estimated Performance 22
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SUMMARY
Purpose
This report presents factual technical data on A. V. Roe, Canada, Limited, proposed development, 
Project Y2 (Secret).  this proposal is the second of two designs which can be classified as 
radical aircraft designs.  The ultimate purpose of presenting this is two-fold; to correct the 
distorted picture presented in previous releases, both classified and unclassified, and to acquaint 
the intelligence community with the current state-of-the-art facts thereby alerting them to any air
intelligence information which may become available indicating Soviet interest in this specialized 
field.
Factual Data
Several news mediums have published articles concerning A. V. Roe, Canada, Limited, Project 
Y2 (Secret) which, when supplemented by the December Air Intelligence Digest article, 
"The Flying Disk", present an inaccurate picture of the proposed project.  It was decided that 
a factual account of this project would be presented, in the form of a Joint Wright Air 
Development Center - Air Technical Intelligence Center, to the intelligence agencies to correct 
any misgivings brought about by the above mentioned articles.
Discussion
The subject of this report deals with a proposal for a new type of aircraft by one of Canada's 
most progressive members of the aircraft industry, AVRO Aircraft, limited, a member of the 
Hawker-Siddley group.  This project should in no way be associated with any science fiction 
for "Flying Saucer" stories because of its external appearance.  the configuration was a result 
of an engineering investigation into the solution of a particular problem.
An examination  of the AVRO proposal shows that the potential for a very high performance 
weapon system exists in the not-to-distant future.  Although thisproposal offers the USAF 
a potentially advanced weapon system having both vertical take-off and military performance 
capabilities, there are numerous technical problems which must be solved before a successful 
development can be realized.
The proposal is for the design of a supersonic research aircraft having a circular planform and 
VTO characteristics.  One version provides for the use of several conventional radial-flow 
type engines.  Another unusual feature of this proposal is that the control of the aircraft is 
accomplished by selective direction of the exhaust gases which eliminates the necessity of 
conventional aerodynamic control surfaces.
Conclusions
This proposal offers a possible solution to the USAF requirement for achieving dispersed base 
operations.
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There appears to be no fundamental reason why this proposal should not be ultimately result 
in a weapon system, however there are several technical areas which must be investigated 
before a full-scale development program is initiated.
The simplicity of airframe construction should alleviate many of the manufacturing and logistic 
problems normally associated with new aircraft developments.
Based an the above conclusions, a two-fold intelligence program is justifiable.
         a.  The technical information on this project should be followed by direct liaison between 
WADC and ATIC personnel.
         b.  A collection effort should be initiated to determine whether the Soviet Bloc is or has 
been conducting research efforts on a similar project, when this work began, and the present 
state of the Soviet development.
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                                                 SECTION I
                                         CHARACTERISTICS
A.   Background
There is a USAF requirement to develop a means of operation from dispersed bases. This 
requirement stems from the growing and possibly catastrophic vulnerability of conventional air 
bases.  The major feature of conventional air bases is the runway, which has grown wider, 
thicker, and longer as aircraft have become heavier and faster.  The operational necessity of 
runways leads to concentrations of aircraft which have become critical targets.  The logical 
approach to dispersed base operation would the appear to be toward reducing the length 
of runways or to their total elimination.  Numerous schemes have been proposed, investigated, 
and some developed to reduce the take-off distance of aircraft.  Among them re water ejection, 
afterburning, and RATO.  Drag chutes and methods of thrust reversal have been developed
for reducing landing requirements.  Attempts to eliminate runways completely have resulted in 
helicopters, convertiplanes and what is known as VTO aircraft.
There are two general types of VTO aircraft - "tail sitters" and "flat risers".  A flat-riser takes 
off in the vertical direction in a normal horizontal flight attitude, while the tail-sitter takes of 
vertically from a position which is 90 degrees to a normal horizontal flight attitude.  Examples 
of tail-sitters are the United States Navy projects with Lockheed and Convair which utilize 
a turboprop power plant, and the USAF project with Ryan Aeronautical Corporation utilizing
turbojet power plants.  Examples of the flat-riser are the Rolls-Royce "Flying Bedstead" and 
the Bell VTO aircraft.  The basic design problem associated with any aircraft of this type 
becomes one of achieving in a single vehicle VTO and military performance capabilities.  A 
possible solution to this problem has been proposed by A. V. Roe, Canada, Limited, in the 
form of their Project Y2 (Secret).
B.   Description of the Proposed Aircraft
      1.  General Description
Two versions of small research VTO aircraft have been designed by the contractor, which, by 
company designation, are Project Y (Secret), a "tail-sitter, and Project Y2 (Secret), a "flat-riser".  
Early in the investigation, Project Y (Secret) was rejected by the contractor in favor of  the 
flat-riser. Project Y2 (Secret) design proposal incorporates a number of advance improvements 
brought about by the  utilization of several radical ideas in fundamental areas which, as yet, have 
not been thoroughly investigated.  the original proposal was essentially for the construction of a 
very large radial flow gas turbine engine which, when covered, will form a flying wing with a 
circular planform, similar in appearance to a very large discus.  the engine is designed to fly 
"edge on" to the wind instead of axially as is present practice ion conventional aircraft design.  
An alternate version for a multi-engine aircraft as shown in Figures 1 and 2 would avoid 
concurrent development of the airframe and engine while providing the other essential characteristics 
of the vehicle.
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The cockpit is located at the center of the aircraft with the orientation of the cockpit determining the 
fore and after center-line of the aircraft as well as the normal direction of forward flight.  The 
airframe, fuel cells, and the gas turbine power plant encircle the cockpit.  (See Figs 3 and 4.)
This aircraft is designed for vertical take-off and landings while in the horizontal flight attitude, 
i.e., a "flat-riser".  Since this aircraft rises vertically from a horizontal position, it does not require 
a landing gear or auxiliary landing devices.  The flat-riser flight take-off technique, the elimination 
of the landing gear and auxiliary landing devices , are brought about by the peripheral exhaust 
which produces a "powerful ground cushion effect" (Fig 5). This is one of the fundamentals on 
which this new radical aircraft design is based.
Since this airframe and engine will have a circular planform, the outer perimeter of the aircraft will 
be the exhaust of the engine and the thrust forces will be used for control of the aircraft.  A unified 
control system must be designed which will produce the same aircraft responses irrespective of 
whether the aircraft is in hovering, transition, or forward flight.  the circular planform may be 
modified to accommodate trim flaps of some nature if they are found to be necessary.
The air intakes are placed in the inner circle on the upper surface of the aircraft for vertical take-off 
while additional air intakes are installed in the upper and lower forward facing surfaces for forward 
flight.
A multi-engine configuration (Figs 1 and 2) is proposed as a research vehicle for the purpose of 
investigating stability and control, performance, etc., before development of a multi-engine 
operational aircraft or radial-flow single-engine aircraft.  this prototype configuration will also 
investigate certain fundamental areas concerning aircraft behavior; an example is the ground 
cushion effect.
      2.  Airframe
The cutaway (Fig 4) of the research aircraft with the radial flow engine shows the details of the 
aircraft structure.  The center location of the fuel cells allows for the use of the fuel as a coolant 
medium against aerodynamic heating for the cockpit.  the mechanical engineering details should 
not present any unsolvable problems in the airframe design; however, the rotor assembly and 
exhaust control systems are considered major problems.  The basic structural ribs of the airframe
lend themselves readily to mass production since they are identical.  Sixty ribs are proposed as 
the foundation of the airframe.  These ribs "butted" to the outer surface of the fuel cells with the 
inner side of the fuel cells comprising the cockpit opening.  for the multi-engine version (Figs 1 and 
2) certain engineering problems may arise due to the complexity of controlling eight engines, eight 
fuel systems, eight lubricating systems, etc.
      3.  Air Intake
The aircraft, at rest, cannot use the bottom forward facing air intake, therefore, "take-off air is 
supplied through 30 square feet of releaving door area
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Page 5  =  Fig. 3 - Three View general Arrangement of Research Aircraft
Page 6  =  Fig. 4 - Section Cutaway of Research Aircraft (Radial Flow Engine)
Page 7  =  Fig. 5 - Ground Cushion Effect

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TABLE  I
PHYSICAL CHARACTERISTICS
Radial-Flow Engine Aircraft
         Particulars                                                                  Values
Weight Dimensions, etc.
Aircraft Gross Take-off Weight lb 29,000
Gross Wing Area sq ft 670
Span (" diameter) ft 29.2
Height over canopy ft 3.75
Standard mean chord ft 23.2
Aspect ratio --- 1.27
Mean t/c ratio excluding intake --- 0.06
Intake base area sq ft 20.0
Approximate jet base area in forward flight sq ft 16.0
Wing loading at mean weight of 26,000 lbs lb/sq ft 38.8
Maximum internal fuel Imp gal
U.S. Gal
950
1,140
Take-off thrust/weight ratio --- 1.73
SLS thrust/frontal area lb/sq ft 900
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TABLE  II
WEIGHT BREAKDOWN
Radial-Flow Engine Aircraft
       Particulars                                                              Lb          Totals
Aircraft Main Structure   9,532
Cockpit well and fuel tank    696
Intake structure 1,341
Main structure 2,904
Outer wing and exhauster 2,990
Halo    781
Cockpit and canopy    165
Control shutters    410
Control system    245
Power plant 10,450
Rotor assembly 5,750
Stator blades, plates and attachments 2,120
Combustion system 1,180
Air bearing assembly 1,400
Extra to structure   1,068
Cockpit equipment    115
Radio and electronics    352
Fuel system    284
Air conditioning and oxygen    250
Miscellaneous     84
AIRCRAFT EMPTY WEIGHT 21,050
Disposable load   7,950
Crew    200
Fuel 7,750
AIRCRAFT GROSS TAKE-OFF WEIGHT 29,000
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in the top intake."  This air is exhausted through exhaust nozzle (outer perimeter) of the aircraft and
is  directed downward (see Figs 6 and 7).  This downward ejectionof the air produces a "ground 
cushion effect", (see Fig 5) which results in an additional thrust component for take-off and allows 
for a ground cushion to brake the landing of the aircraft.  the effect is present only when he exhaust
air is distributed from the periphery of the aircraft (flat-risers).  (See Fig 8.)
In forward flight, the air enters the plenum chamber through  the forward facing air intakes in both
the upper and lower surfaces of the aircraft.  Engine exhaust gasses are carried around the 
exhauster duct and are expelled through the  annular nozzle which is located on the upper and 
lower surfaces near the periphery, and through the backward facing nozzles which are located on 
both sides of the aircraft.  (See Fig 9.)
      4.  Propulsion System
The proposed power plant for the single-engine research vehicle is basically a double-sided 
radial-flow turbojet engine.  The heart of this engine is a very large diameter rotor disc which 
utilizes compressor air bleed as its onlymeans of lubrication.
The compressor stators, diffuser, combustion tubes, and turbine nozzle guide vanes are designed as
an integral part of the airframe. The rotating element of the conventional gas turbine engine, namely, 
the compressor rotor, connecting shaft and turbine wheel have been rearranged to a disc 
configuration.  The compressor rotor blades are mounted vertically on the inner disc ring; the 
turbine wheel blades are mounted vertically on the outer disc ring, and the connecting disc ring is 
comparable to the conventional connecting shaft.  This disc rotates on a double-sided air bearing 
mounted between the upper and lower combustion tubes.
The combustion system consists of flame tubes distributed between the structural ribs of the 
aircraft.  the engine pressure is contained between the outer skin and the rotor bearing plates with 
the latter structure being mounted between the combustion tubes.  For take-off the intake air is 
brought through the top intakes to the first stage of the rotor and is compressed radially outwards
through six stages giving a normal pressure ratio of 3 to 1.  from the last compressor stage, the air 
is diffused and passes through the flame tubes, turbine inlet guide vanes, through the turbine wheel, 
and then through the exhaust nozzle which is the outer perimeter of the aircraft.  (See Fig 10)  
During forward flight, the upper air intake ducts are closed and the forward facing air intakes are 
open.(See Fig 11.)
Due to the radial flow through the engine, the compressor blades and turbine blades are straight.  
Therefore, these parts may be more easily manufactured than for the conventional engine 
compressors and turbines.
The proposed air bearing supporting the rotating element eliminates many of the problems which are
imposed by mechanical type bearings.  The large area if the bearing surface, approximately 100 
square feet on both sides, is available to support the weight of the very large turbine rotor.  The air
supply for the flat bearing comes from "secondary air" in the combustion region while the supply for
the
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Page 11  =  Fig. 6 - Airflow Into Intake During Take-off and Landing
Page 12  =  Fig. 7 - Section of Airflow Pattern for Take-off
Page 13  =  Fig. 8 - Typical Section of Exhauster Duct Showing Take-off Gas Flow
Page 14  =  Fig. 9 - Section Through Rear of Aircraft at Supersonic Speed
Page 15  =  Fig. 10 - Typical Cross-Section Through Engine
Page 16  =  Fig. 11 - Through Flow at Low Forward Speed

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vertical bearing comes from the rear of the last rotor stage of the compressor.  Exhaust of the 
bearing air is controlled by a low pressure annulus and the main "exhauster" which utilized this air 
for cooling the turbine blade roots.  Figures 12 and 13 show graphically the flow within the air 
bearing.
A ground supply of compressed air applied to the air bearing will be used when starting the engine.
In stopping the engine, the rotor will ground on self-lubricating bearing pads.  the material used in 
the on self-lubricating bearing pads will be cast iron or carbon which will provide good dry bearing
surfaces on steel.  These pads are note expected to suffer excessive wear or provide undue 
stopping torque on the turbine rotor.
The multi-engine version would utilize numerous small engines having low specific weights to 
provide  the exhaust gases.
       5.  Control Systems
the aircraft is controlled by regulating shutters which vary the amount of thrust through the annular 
nozzles (for pitch and roll control) and through the backward facing nozzles for yaw control located 
on the peripheral edge.  (See Fig 14.)  The contractor claims that the use of this "jet control" at all 
times eliminates the difficulty associated with hinged control surfaces in supersonic flight.  This 
statement on the part of the contractor is based on initial testing of the principle and much more 
data must be assembled before it can be completely accepted.
A proposed method of achieving jet control utilizes the so-called "Coanda effect" whereby a jet 
stream is deflected through large angles by having a curved surface in contact with its edge at one 
side.  (See Fig 15.)  Additional investigation into the mechanism required to utilize this effect must 
be accomplished in  the early phases of this development.
In the proposed aircraft thrust forces are used for control at all times.  It is mandatory to use the 
thrust force for take-off and hovering flight since there are no aerodynamic forces available due to 
the lack of forward movement.  In forward supersonic flight thrust forces are used in lieu of 
conventional hinged-type controls.  Some thought has been given to the mechanics of the control 
system as can be seen in Fig 14.
C.  Performance
The performance estimated by the contractor was based on rather broad assumptions and has not 
as yet investigated by a wind tunnel test program.  (See Table III.)
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Page 18  =  Fig. 12 - Cross-Section Showing Bearing Airflow
Page 19  =  Fig. 13 - Perspective View Showing True Path of Bearing Air
Page 20  =  Fig. 14 - Exhaust Jet Angles at Low Forward Speed
Page 21  =  Fig. 15 - Coanda Effect:  High Aspect Ratio Jet Bending

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TABLE  III
CONTRACTOR ESTIMATED PERFORMANCE
Radial-Flow Engine Aircraft
                                                                                                          Without      With 1500 Deg
     Particulars                                                                                      Reheat         K Reheat
Maximum level speed mph 1,720 2,300
knots 1,490 2,000
Mach No. 2.6 3.48
Ceiling (Max power at mean wt) ft 71,600 80,600
Time from hovering start to NA
36,090 ft min 1.76 NA
60,000 ft min 2.66 NA
70,000 ft min 4.2 NA
Still air range with allowances for take-off, climb, cruisedescent and landing miles miles 620 NA
Take-off and landing distances --- Nil Nil
Max hovering alt from take-off ft 10,000 NA
Max hovering alt at mean wt, 26,000 lbs ft 18,000 NA

NOTE: The above estimate utilizes net thrusts and SFC which are based on the "simplifying assumption" - "Plain nozzles and 100 per cent thrust recovery from thejet bending."

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