CUFONSM The Computer UFO Network http://www.cufon.org/ [email protected] Dale Goudie – Information Director, Jim Klotz – SYSOP, Chris Lambright - Webmaster Adobe Portable Document Format Version of TR-AC-47, JOINT ATIC-WADC REPORT ON PROJECT SILVER BUG Project No. 9961, 15 February 1955 PDF version created and posted 14-June-2002. Originally posted on CUFON 01-May-1998. The Project SILVERBUG report. Joint Wright Air Development Center - Air Technical Intelligence Center Report on Project Silver Bug, Technical Report No. TR-AC-47, project No. 9961, dated 15-Feb-1955. Presents technical data on A. V. Roe, Canada, Limited, design proposal for development Project Y2, a circular planform, flat-riser aircraft. 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. For authoritative information on the Avrocar and other Avro projects we recommend: AVROCAR: Canada’s Flying Saucer: the story of Avro Canada’s secret projects, by Bill Zuk, © 2001 Bill Zuk, The Boston Mills Press, Ontario Canada, ISBN 1-55046-359-4 - Jim Klotz CUFON SYSOP Adobe Acrobat ® Software underwritten by: Roderick Dyke Archives for UFO Research, News and Information Services DEPARTMENT OF THE AIR FORCE AIR INTELLIGENCE AGENCY 6 Mar 1998 NAIC/SCVMS (FOIA) 4180 Watson Way Wright-Patterson AFB OH 45433-5648 Dale Goudie ADDRESS REMOVED BY CUFON 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 [Signed] GERY D. HUELSEMAN, MSgt, USAF Chief, Freedom of Information Act Information Management Operations Attachment Project Silver Bug Golden Legacy, Boundless Future...Your Nation's Air Force TECHNICAL REPORT Declassified 29 MAR 95 Auth: DOD 5200.1.R SAF/AAZD (Unclassified) TR-AC-47 JOINT ATIC-WADC REPORT ON PROJECT SILVER BUG PROJECT NO. 9961 15 FEBRUARY 1955 DEPARTMENT OF THE AIR FORCE AIR TECHNICAL INTELLIGENCE CENTER WRIGHT-PATTERSON AIR FORCE BASE OHIO UNCLASSIFIED 1. Information conflicting with or pertinently 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 affecting 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 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 UNCLASSIFIED TABLE OF CONTENTS Summary ... iii Section I Characteristics ... 1 A. Background ... 1 B. Description of the Proposed Aircraft ... 1 C. Performance ... 17 Section II USAF Research and Development Status ... 23 A. Principal Problem Areas ... 23 B. Present Development Status ... 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 Speed ... 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 Coanda Effect: High Aspect Ratio Jet Bending ... 21 Page i UNCLASSIFIED TABLE OF CONTENTS (Cont) Table I Physical Characteristics ... 8 Table II Weight Breakdown ... 9 Table III Contractor Estimated Performance ... 22 Page ii UNCLASSIFIED 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 Disc", 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 study, 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 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 or "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-too-distant future. Although this proposal 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 axial-flow engines, while the ultimate aircraft configuration utilizes a new radial-flow type engine. 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. Page iii UNCLASSIFIED There appears to be no fundamental reason why this proposal should not 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 on 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. Page iv UNCLASSIFIED SECTION I CHARACTERISTICS A. Background There is a USAF requirement to develop 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 then 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 are 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 off vertically from a position which is 90 degrees to a normal level 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 the present practice in 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. Page 1 UNCLASSIFIED Fig. 1 Three-View General Arrangement of Proposed Multi-Engine Research Aircraft [Diagram showing top, front, and side views of the 21'-6" diameter circular planform multi-engine research aircraft with a height of 4'-0" and a central cockpit bubble.] Page 2 UNCLASSIFIED Fig. 2 Cut Away of Research Aircraft [Diagram labeling: Vertical Take Off Intake Doors, Canopy, Main Structure, Ejection Seat, Engine Access Door, Intake Roof, Air Intake Sliding Doors, (8) Viper Axial Flow Gas Turbine Engines, Control Shutter, Floor Window, Outlet Vanes, Segmental Jet Pipe] Page 3 UNCLASSIFIED 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 auxilliary landing devices. The flat-riser flight take-off technique, the elimination of the landing gear and auxilliary landing devices, are brought about by the peripheral exhaust which produces a "powerful ground cushion effect" (Fig 5). This is one of the fundamentals upon 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 nozzle 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 system 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 are "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 releasing door area in the top intake." Page 4 UNCLASSIFIED Fig. 3 Three-View General Arrangement of Research Aircraft [Diagram showing top, side, and front profile views of the 29'-2" diameter radial-flow engine aircraft with a 3'-9" height.] Page 5 UNCLASSIFIED Fig. 4 Section Cutaway of Research Aircraft (Radial Flow Engine) [Diagram labeling: Air Intake Shutter Doors, Fixed Outer Ring, Combustion System, Turbine, Upper Air Bearing Plate, Disc Rotor, Compressor, Fuel Tanks, Sliding Shutters Controlling Nozzle Area, Basic Structural Ribs, Rudder Nozzles, Take Off Air Intake Doors] Page 6 UNCLASSIFIED Fig. 5 Ground Cushion Effect [Cross-sectional diagram illustrating peripheral jet flow downward and toroidal recirculation vortices creating the ground cushion effect beneath the circular craft.] Page 7 UNCLASSIFIED TABLE I PHYSICAL CHARACTERISTICS Radial-Flow Engine Aircraft Particulars | Values Weight Dimensions, etc. Aircraft Gross Take-off Weight: 29,000 lb Gross wing area: 670 sq ft Span (= diameter): 29.2 ft Height over canopy: 3.75 ft Standard mean chord: 23.0 ft Aspect ratio: 1.27 Mean t/c ratio excluding intake: 0.06 Intake base area: 20.0 sq ft Approximate jet base area in forward flight: 16.0 sq ft Wing loading at mean weight of 26,000 lbs: 38.8 lb/sq ft Maximum internal fuel: 950 Imp gal / 1,140 U.S. gal Take-off thrust/weight ratio: 1.73 SLS thrust/frontal area: 900 lb/sq ft Page 8 UNCLASSIFIED 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: 118 Radio and electrics: 352 Fuel system: 264 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 Page 9 UNCLASSIFIED This air is exhausted through exhaust nozzle (outer perimeter) of the aircraft and is directed downward (see Figs 6 and 7). This downward ejection of 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. This effect is present only when the 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 gases 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 only means 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 outward 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 of 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 Page 10 UNCLASSIFIED Fig. 6 Airflow Into Intake During Take-off and Landing [Isometric line drawing showing vertical flow of air into the circular top intake ring during takeoff and landing operations.] Page 11 UNCLASSIFIED Fig. 7 Section of Airflow Pattern for Take-off [Cross-section diagram illustrating intake air entering upper louvers, passing radially through the engine, and deflecting downwards at the perimeter.] Page 12 UNCLASSIFIED Fig. 8 Typical Section of Exhaustor Duct Showing Take-off Gas Flow [Cross-section showing duct velocities from Duct Mach No. 0.6 at turbine exit, 0.25, 0.2 in duct, through top and bottom shutters to Duct Mach No. 0.95 at take-off jet.] Page 13 UNCLASSIFIED Fig. 9 Section Through Rear of Aircraft at Supersonic Speed [Aerodynamic diagram detailing trailing edge shock wave, region of breakaway, and flow around peripheral aerodynamic trailing edge at supersonic speed.] Page 14 UNCLASSIFIED Fig. 10 Typical Cross-Section Through Engine [Cross-sectional drawing showing compressor rotor, stator blades, stator plate, shroud seal, flame tubes, turbine rotor, and station numbering.] Page 15 UNCLASSIFIED Fig. 11 Through Flow at Low Forward Speed [Diagram showing air entering forward-facing intake sectors, circulating through radial engine paths, and discharging asymmetrically through peripheral nozzles at low forward speed.] Page 16 UNCLASSIFIED 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 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 self-lubricating bearing pads will be cast iron or carbon which will provide good dry bearing surfaces on steel. These pads are not 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 been investigated by a wind tunnel test program. (See Table III.) Page 17 UNCLASSIFIED Fig. 12 Cross-Section Showing Bearing Airflow [Diagram showing detailed paths of pressurized bearing air film cushioning the rotating disc between upper and lower stator/combustion structures.] Page 18 UNCLASSIFIED Fig. 13 Perspective View Showing True Path of Bearing Air [Perspective cutaway showing direction of rotation, top and bottom bearing plates, air supply holes, and rotor disc.] Page 19 UNCLASSIFIED Fig. 14 Exhaust Jet Angles at Low Forward Speed [Diagram showing thrust vector percentages and angular deflections around the circular perimeter: 97% thrust at forward-flank sectors, 99% thrust directed 10° aft/downward, and 22% thrust at rear sectors.] Page 20 UNCLASSIFIED Fig. 15 Coanda Effect: High Aspect Ratio Jet Bending [Schematic diagram detailing fluid dynamics of high aspect ratio jet sheet bending around a curved cylinder/surface via Coanda effect.] Page 21 UNCLASSIFIED TABLE III CONTRACTOR ESTIMATED PERFORMANCE Radial-Flow Engine Aircraft Particulars | Without Reheat | With 1500°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): 71,600 ft | 80,600 ft Time from hovering start to: 36,090 ft: 1.76 min | NA 60,000 ft: 2.66 min | NA 70,000 ft: 4.2 min | NA Still air range with allowances for take-off, climb, cruise, descent, and landing: 620 miles | NA Take-off and landing distances: Nil | Nil Max hovering alt from take-off: 10,000 ft | NA Max hovering alt at mean wt, 26,000 lbs: 18,000 ft | 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 the jet bending." 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