SECRET PROJECT 1794 FINAL DEVELOPMENT SUMMARY REPORT 2 APRIL - 30 MAY 1956 USAF Contract No. AF33(600)30161 I. D. No. 56-RDZ-19954 AVRO AIRCRAFT LIMITED DECLASSIFIED Authority NND63253 SECURITY WARNING This document is intended solely for the recipient and such persons as have been delegated to use it in the course of their duty and may be used in connection with work performed for or on behalf of the United States Air Force. The transmission, unauthorized retention, destruction, or the revelation of its contents, in any manner, to (an) unauthorized person(s) is forbidden. Failure to comply with any of the above instructions is an infraction of the Canadian Official Secrets Act and is a violation within the meaning of the United States Espionage Laws, title 18, U. S. C., sections 793 and 794. This copy has been issued by Avro Aircraft Limited, Malton. To - Date - Copy No. - 1 I. D. 56 RDZ 19954 1 JUNE, 1956 SECRET PROJECT 1794 FINAL DEVELOPMENT SUMMARY REPORT 2 April, 1955 - 31 May, 1956 USAF Contract No. AF33(600)30161 Issued by: Avro Aircraft Limited Malton, Ontario, Canada Approved by: J. C. M. Frost Chief Design Engineer Special Projects Group Avro Aircraft Limited. H. C. Moody Engineering Manager Special Projects Group Avro Aircraft Limited. The number of pages in this report, including the Title, Table of Contents and Illustration sheets is 114. 1 JUNE, 1956 I. D. No. 56-RDZ-19954 SECRET TABLE OF CONTENTS 1. SUMMARY - Page 1 2. INTRODUCTION - Page 2 3. PROGRESS OF THE DESIGN - Page 3 4. PROJECT 704 - Page 8 4.1 Description - Page 8 4.2 Operation - Page 11 4.3 Performance - Page 15 5. DISCUSSION OF ACTIVITIES - Page 20 5.1 Test Results - Page 20 5.2 Design Study & Theoretical Analysis - Page 74 6. FINANCIAL STATEMENT - Page 87 7. DEVELOPMENT AND PRODUCTION ASPECTS - Page 96 8. NEW PROGRAMS REQUIRED - Page 98 8.1 Tests Program - Page 98 8.2 Design Study and Theoretical Analysis - Page 103 9. TABULATED SUMMARY & COST FORECAST - Page 110 1 JUNE, 1956 I. D. No. 56-RDZ-19954 SECRET AVRO AIRCRAFT LIMITED - PROJECT 1794 FINAL DEVELOPMENT SUMMARY 1. SUMMARY In this report the scope of work under the above contract is reviewed and the progress of the design is explained. An outline of the proposed research prototype which the contractor is building is then given, followed by the results of feasibility and performance potential studies for the subject aircraft, and a financial statement relating to the work accomplished. It is concluded that the stabilization and control of the aircraft in the manner proposed - the propulsive jets are used to control the aircraft - is feasible and the aircraft can be designed to have satisfactory handling through the whole flight range from ground cushion take-off to supersonic flight at very high altitude. Supersonic tests show that the calculated thrust potential with the present design will provide a much superior performance to that estimated at the start of contract negotiations, with a top speed potential between Mach 3 and Mach 4, a ceiling of over 100,000 ft. and a maximum range with allowances of about 1,000 nautical miles. Additional tests to completely substantiate this performance are shown to be required. Development and production aspects are briefly reviewed and an outline new program broader in scope than the study now completed is presented (to dovetail with the development envisaged), together with an accompanying cost estimate. This estimate covers a period of 18 to 24 months in the total amount of $3,168,000. 1 JUNE, 1956 Page 1 AVRO AIRCRAFT LIMITED - PROJECT 1794 2. INTRODUCTION The work statement - Exhibit 1 of the above contract - specifies "analytical investigations and design studies to determine the performance capabilities and design features of a flat vertical take-off and landing aircraft", of a new type proposed by AVRO AIRCRAFT LIMITED: together with substantiating tests. This contract is essentially a feasibility study and "design configuration effort shall be confined to the minimum required for demonstration of principles in a practical application". The areas for test and analysis are defined as: (1) Air Cushion effect (2) Stability of multi-engine configuration (3) Air Intake and gas exhaust system test (4) Aircraft performance, stability and control (5) Radial flow engine feasibility The progress of work has been reported in detail in ten monthly progress reports of which the first group were summarized in an interim development summary report. The whole period is covered by this final development summary and the work under this contract is now completed. Separate technical reports have been prepared on each of these five areas, plus three further separate reports covering wind tunnel model tests. A general technical summary I. D. No. 56RDZ-13709 reviews all the work done during the year from the technical standpoint and outlines the current status of the design. 1 JUNE, 1956 Page 2 AVRO AIRCRAFT LIMITED - PROJECT 1794 3. PROGRESS OF THE DESIGN At the start of contract negotiations the proposed design (Fig. 1 on the following page) was for a jet-propelled all-wing aircraft of circular planform, embodying a new arrangement of a turbo-jet engine and employing jet control. In order to separate the engine development task from that of the airframe an intermediate research vehicle employing 8 small conventional turbo-jets radially disposed like the spokes of a wheel was also proposed at this time (Fig. 2). An alternative final development to the large radial engine of Fig. 1 was also suggested (Fig. 3). At the beginning of the contract period a compromise between the Fig. 1 and Fig. 3 designs was conceived, having a superior performance to either. This ducted fan arrangement - while preserving the radial flow and circular planform with air cushion VTOL, avoided some considerable objections to the earlier designs and also gave good static thrust-lift efficiency and a very thin wing, using the entire depth of the wing between skins for engine air flow. This design was developed under contract area (5) through several mechanical arrangements to the form shown in Fig. 4 and has supplanted the earlier designs. In view of the relatively minor task of developing the main rotors of Fig. 4 by comparison with the engine of Fig. 1, the idea of an intermediate vehicle has been discarded and AVRO AIRCRAFT LIMITED is proceeding with the construction of the aircraft illustrated in Fig. 4, which is described in general terms in the next section. 1 JUNE, 1956 Page 3 AVRO AIRCRAFT LIMITED - PROJECT 1794 FIG. 1 ORIGINAL RADIAL ENGINE DESIGN (Cutaway illustration) Features indicated: Air Intake Sliding Doors, Fixed Outer Ring, Combustion System, Turbine, Upper Air Bearing Plate, Disc Rotor, Compressor, Sliding Shutters Controlling Nozzle Area, Fuel Tanks, Basic Structural Ribs, Rudder Nozzles, Take-off Air Intake Doors. Page 4 AVRO AIRCRAFT LIMITED - PROJECT 1794 FIG. 2 INTERMEDIATE RESEARCH AIRCRAFT Cutaway illustration showing: - Main Structure - Canopy - Ejection Seat - Engine Access Door - Intake Roof - Air Intake Sliding Doors - (8) 'Viper' Axial Flow Gas Turbine Engines - Control Shutter - Floor Window - Fuel Tanks - Outlet Vanes - Segmental Jet Pipe - Vertical Take-off Intake Doors Page 5 AVRO AIRCRAFT LIMITED - PROJECT 1794 FIG. 3 SECTION CUTAWAY - CONVENTIONAL GAS TURBINE POWER PLANT SUBSTITUTION Page 6 AVRO AIRCRAFT LIMITED - PROJECT 1794 FIG. 4 6-VIPER DUCTED FAN RAMJET DESIGN Cutaway illustration showing: - Pilot's Canopy - Engine Access Panel - Upper Intake - Integral Fuel Tanks - Outer Wing - Inner Wing - Lower Intake - Turbine - Impeller - Engine Air Intake - ASM-Viper 8 Engine - Internal Airflow Ducts - Flame Holders - Trim Metering Valve - Exhaust Diffuser - Flight Control Shutters Page 7 AVRO AIRCRAFT LIMITED - PROJECT 1794 4. PROJECT 704 To distinguish it from the work covered under contract on Project 1794 the undertaking to build the aircraft is known by AVRO AIRCRAFT LIMITED as Project 704. 4.1 Description Fig. 5 is a plan and section drawing of the aircraft. It is 35.3 feet in diameter; stands about 2 feet off the ground, measures 7.7 feet from the lower surface to the top of the canopy; is approximately symmetrical in section and is expected to weigh about 20,000 lb. with 5,700 lb. fuel. The maximum fuel capacity is 13,150 lb. giving a maximum weight of about 27,000 lb. Six Armstrong Siddeley Viper turbo-jets - 1,900 lb. thrust, 22.0" overall diameter, 525 lb. weight each - are mounted radially in the wing, exhausting inwards; and used as gas generators to drive a pair of contra-rotating centrifugal impellers by means of a radial inflow turbine. The 8 foot diameter impellers, which rotate slowly by comparison with conventional centrifugal turbo-jets, draw air from the upper and lower intakes and force it radially out through the wing between the Viper engines. Some of the air thrown out by the impellers is directed back to feed the Viper engines (Fig. 6), which thus behave statically as though there was ram pressure from forward flight on their air intakes. 1 JUNE, 1956 Page 8 AVRO AIRCRAFT LIMITED - PROJECT 1794 FIG. 5 PLAN VIEW AND SECTION THROUGH AIRCRAFT Diagram and Section A-A indicating: - Upper Impeller and Turbine - Upper and Lower Intakes - Flame Holders - Outer Wing - Inner Wing Diffuser Section - Lower Impeller and Turbine - Turbine Exhaust - Pilot's Cockpit - Integral Fuel Tanks - Engine Intake - Flight Control Shutters - 6 A.S.M. Viper 8 Engines - Engine Tailpipe Page 9 AVRO AIRCRAFT LIMITED - PROJECT 1794 FIG. 6 ENGINE INSTALLATION Illustration showing: - Engine Intake and Intake Cascades - A.S.M. Viper 8 Engine - Wing Flow Ducts Page 10 AVRO AIRCRAFT LIMITED - PROJECT 1794 4.1 (Cont'd) The air is diffused in the wing to a high pressure at the flame holders (Fig. 5), where fuel may be added to augment the thrust, and is then exhausted through pneumatically controlled shutters or gills (Fig. 7) which direct the jet as it exhausts all around the aircraft periphery; either to raise the aircraft vertically off the ground or to propel it in forward flight. This control of the exhaust direction enables the jets to be used for manoeuvring and stabilizing the aircraft in all flight conditions, so that separate additional controls are not required to cater for vertical take-off and hovering. Thus, for instance, to pull up the nose of the aircraft the pilot will control the shutters by means of a conventional cockpit stick control to direct the jet out at the top of the wing in the rear sector and thrust the tail down, or to roll he will similarly direct the jet from the top on one wing and from the bottom on the other. For stabilizing, the main rotors and a diaphragm are used to sense when the aircraft pitches in a gust and use is made of the jet controls to correct it. Stabilization through the controls is essential on this aircraft since the centre of gravity is in the middle of the wing at 1/2 the chord from the leading edge, whereas the aircraft would only be stable without using the controls if the centre of gravity were about at the 1/4 chord position. The change in jet direction as the aircraft pitches performs the same function as the fixed stabilizer of a conventional aircraft. 4.2 Operation To take off, all the shutters on top of the wing are closed and shutters on the bottom are opened wide... 1 JUNE, 1956 Page 11 AVRO AIRCRAFT LIMITED - PROJECT 1794 FIG. 7 CUTAWAY OF CONTROL SHUTTERS Illustration showing details of: - Angle of Attack Metering Valve & Fore & Aft Trim Control - Top and Bottom Shutters - Shutter - Shutter Mounting Box - Shutter Control Feed Pipes - Shutter Assembly - Flame Holder A C Structure - Shutter Shuttle Valve - Trim Control Actuator (Manual) Page 12 AVRO AIRCRAFT LIMITED - PROJECT 1794 4.2 (Cont'd) ...on the bottom are opened wide. Without adding fuel to augment it, about 20,000 lb. thrust is produced by the jets pointing downwards all around the wing; however this jet-around-wing configuration produces a powerful take-off ground cushion so that the lift on the aircraft is, in fact, increased to possibly 30,000 lb., and the aircraft rises to about 20 feet (Fig. 8), where the ground cushion effect falls off rapidly. For pure vertical take-off the thrust must now be augmented and the exhaust arrangement modified by the pilot: however, it is envisaged that transition to forward flight will normally be from the ground cushion. By operating a transition control the pilot leans the jets backwards gradually to accelerate the aircraft, and raises the nose; with the thrust less than the weight, the aircraft can accelerate and rise into free air a short distance from the starting point. In forward flight ram pressure is collected into the air intake which increases the pressure at the flame tubes and makes burning more efficient. At supersonic speed augmentation is always used and because of the large mass of air the impellers can handle, a very large thrust and high top speed is possible. The large installed thrust also leads to a high thrust to weight ratio which makes a very high ceiling possible. The efficiency of the airframe at supersonic speed appears good and that of the engine reasonable, so that a long supersonic cruise range is also forecast. For landing, either a fully vertical descent may be made, with or without thrust augmentation from a hot main jet, or a steep approach path to the ground chosen... 1 JUNE, 1956 Page 13 AVRO AIRCRAFT LIMITED - PROJECT 1794 FIG. 8 GROUND CUSHION EFFECT Diagram illustrating airflow patterns under the circular wing creating the ground cushion effect. Page 14 AVRO AIRCRAFT LIMITED - PROJECT 1794 4.2 (Cont'd) ...without thrust augmentation from a hot main jet, or a steep approach path to the ground chosen. Transition to the landing condition from in-flight is similar to the take-off transition. The nose is raised and the jets transferred to the undersurface and leaned forward collectively to rapidly slow the aircraft down; as the speed falls close to zero the nose is lowered to bring the aircraft into the fully hovering condition. On sinking into the ground cushion the pilot must then close the throttle to reach the ground. 4.3 Performance The performance of the first prototype will initially be restricted due to a Mach No. restriction on the Viper engines. The following summary assumes this restriction has been removed: At 1200°K main combustion temperature: - Max. level speed: (Fig 9) Mach 3.0 - Supersonic ceiling: (Fig 10) 94,000 feet - Altitude for normal acceleration of 7.33g in a steady turn: 53,000 feet - Still air range (full internal fuel) with allowances for take-off climb and acceleration, cruising at Mach 2.25 at 90,000 feet: (Fig 11) 1,000 naut. miles - Take-off and landing: VTOL 1 JUNE, 1956 Page 15 AVRO AIRCRAFT LIMITED - PROJECT 1794 FIG. 9 PROJECT 1794 DRAG AND THRUST vs MACH NO. (35,300 FT.) Graph plotting Drag and Thrust (0 to 90,000 lb) against Flight Mach No. (1.0 to 3.0). Shows curves for: - Net Thrust at 1700°F Main Combustion Temperature - Lb. Thrust at 2240°F - Total Net Drag - Drag Including Trim Thrust Loss - Trim Thrust Loss - 6-Viper Engined Aircraft Page 17 AVRO AIRCRAFT LIMITED - PROJECT 1794 FIG. 10 PROJECT 1794 RATE OF CLIMB AT MACH 2.26 Graph of Altitude (30,000 to 100,000 ft) vs Rate of Climb (0 to 2000 ft/sec): - Aircraft Weight = 21,700 lb - Aircraft Weight = 22,750 lb Page 18 AVRO AIRCRAFT LIMITED - PROJECT 1794 FIG. 11 PROJECT 1794 STILL AIR RANGE Mission profile graph showing Height (0 to 100,000 ft) vs Range Nautical Miles (0 to 1,000): - Subsonic Climb (0 to 36,000 ft) - Level Acceleration at 36,000 ft - Supersonic Climb at Mach 2.25 (36,000 to 90,000 ft) - Cruise at Mach 2.25 at 90,000 ft - Fuel Capacity = 13,120 lb, Reserve = 1,312 lb Page 19 AVRO AIRCRAFT LIMITED - PROJECT 1794 5. DISCUSSION OF ACTIVITIES 5.1 Tests A tabular summary of the following is given at the end of this report. 5.1.1 Wind Tunnel Tests: A program of wind tunnel testing has been carried through during the year in three groups as follows: 5.1.1.1 An important series of subsonic tests, involving over 500 hours testing time and 34 weeks tunnel occupancy has been carried out on a 1/6th scale* reflection plane model. In these tests, which were done in the 20 ft. diameter Massie Memorial Wind Tunnel at Wright Air Development Centre, provision was made for simulating air intake and jet exhaust flows. Fig. 12 is an illustration of the model, Figs. 13, 14 and 15 are photographs of the model and associated equipment. Testing covered all phases of subsonic operation, including static ground cushion effect tests with control, transition to forward flight with control in proximity to the ground and in free air, and in-flight tests with control in free air. * NOTE: The geometry of Project 704 is slightly different to that of the wind tunnel models tested, which were based upon an earlier layout of an aircraft 33 feet dia. with 3 1/2 % thickness/chord ratio wing. Corrections have been made to the performance quoted to account for the difference. 1 JUNE, 1956 Page 20 SECRET FIG. 12 STABILITY AND CONTROL MODEL NO. 2/16 Detailed engineering schematic showing test rig in 20 ft Massie Memorial Tunnel: - Model Drwg No. SK 30082 Sht. 2, Rig Drwg No. SK 30082 Sht. 1 (66" Dia. Model) - Details of Cascade Installation for Forward Flight and Hovering - Exhaust Air Guide Vanes, Exhaust Nozzles, Intake Air Guide Vanes - Balance Turn Table, Potentiometer (Angle of Attack Indication), Flexible Support Column (4) - Drag, Lift, Pitching Moment Dynamometers, Balance Support Base, Air Bearing Flow Dividers, Intake Air Evacuation Duct, Tie-Down Turnbuckle Page 21 AVRO AIRCRAFT LIMITED - PROJECT 1794 FIG. 13 1/6 SCALE SUBSONIC MODEL (Mounted on test rig balance base) FIG. 14 Subsonic Model Reflection Plane Installation (Front Quarter View) FIG. 15 Subsonic Model Reflection Plane Installation (Overhead Plan View) Pages 22-24 AVRO AIRCRAFT LIMITED - PROJECT 1794 5.1.1.1 (Cont'd) Because of the large number of variables - speed, transition control, pitch control, jet thrust, intake flow, ground position and angle of attack - a very complex program was required, which took longer to complete than was anticipated. (Tests were completed June 14). This has caused some delay in the production of final technical reports. Numerous important details were discovered or verified by these tests; broad conclusions are as follows: (i) The aircraft can be satisfactorily controlled during take-off and landing, through a smooth transition to or from forward flight and at all subsonic speeds; and manoeuvred through a satisfactory subsonic flight envelope. (Fig. 16). (ii) It appears that with the thrust less than the weight the aircraft can accelerate and rise smoothly into free air a short distance from the starting point. However, interpretation of the data is difficult since values do not collapse theoretically in the very low speed range and no data was taken very close to zero speed. (iii) The aircraft has a high subsonic zero lift drag coefficient and although it has a remarkable lift efficiency (due to the jet effect and negative margin) its subsonic cruising efficiency is poor, as expected. It appears well worth while to reduce subsonic drag in order to improve acceleration, and subsonic endurance. (Fig. 17). Further tests with this model are required: (i) To obtain transition data down to very low speed. Even low accuracy data would be regarded as valuable confirmation of the transition flight path. 1 JUNE, 1956 Page 25 SECRET FIG. 16 PROJECT 1794 FLIGHT ENVELOPE S. L. AIRCRAFT WEIGHT = 20,000 LB Graph of load factor n (g's: -3 to +8) vs Mach Number (0.2 to 1.2): - Shows Trim Limitation boundaries for Max 'Hot' Thrust, Max 'Cold' Thrust, and Engine Idling (producing enough power to overcome momentum drag) - Boundary line for CL = 1.0 Page 26 SECRET FIG. 17 L/D TRIM vs ALPHA (Angle of Attack) Graph plotting (CL/CD)TRIM (-6 to +6) against alpha (-6° to +10°) for various jet momentum coefficients (Cj = .08, .14, .22, .30). Page 27 AVRO AIRCRAFT LIMITED - PROJECT 1794 5.1.1.1 (Cont'd) (ii) To investigate the surface pressure distribution on the aircraft in various flight conditions. (iii) To investigate control scheme modification to improve transition control characteristics through the whole angle of attack-ground distance range, and to improve subsonic cruising efficiency. (iv) To check the effect of simulating the exhaust with a hot jet on the drag and the aerodynamic characteristics, (originally planned, but postponed). (v) To investigate reducing the subsonic drag by intake modification. 5.1.1.2 Three supersonic models have been tested involving 76 hours test time and eight days tunnel occupancy. These tests were done in the Massachusetts Institute of Technology Naval Supersonic Laboratory 18" x 24" section supersonic tunnel. These models were: (i) A sting mounted 1/40 scale* model built up by components, with no flow simulation. (Figs. 18 and 19). (ii) A 1/23 scale* reflection plane force model, with air intake, jet flow and control position simulation. (Figs. 20 and 21). * See footnote at bottom of page 20. 1 JUNE, 1956 Page 28 SECRET - AVRO/SPG/TR6 FIG. 19 PERFORMANCE MODEL NO. 4/21 (9" Dia. Model) Drawings of configurations tested: - Model No. 4/21/1 (Wing only) - Model No. 4/21/2 (Wing and 45° Ramp) - Model No. 4/21/3 (Wing, 45° Ramp and Solid Intake) - Model No. 4/21/4 (Wing, Concave Ramp and Ducted Intake) - Model No. 4/21/5 (Wing, 45° Ramp and Ducted Intake) - Model No. 4/21/6 (Wing, 30° Ramp and Ducted Intake) Strain gauges for pitching moment and drag measurement. FIG. 18 PHOTOGRAPHS OF THE WRC1D CONFIGURATION AS INSTALLED IN THE M. I. T. - N. S. L. SUPERSONIC WIND TUNNEL (Forward upper surface and rear views). Pages 29-30 SECRET FIG. 20 STABILITY AND CONTROL MODEL NO. 2/20 (17.4" Dia. Model in M.I.T. Tunnel) Diagram illustrating: - Exhaust Nozzle Air Supply Line, Intake Air Evacuation Line, Air Bearing, Floating Plate, Magnesyn Position Transmitter - Model No. 2/20/1AC, Exhaust Nozzles, Air Intake Pitot Probes, Reflection Plane, Removable Tip, Flexible Support Column, Drag/Lift/Pitching Moment Dynamometers. Page 31 AVRO AIRCRAFT LIMITED - PROJECT 1794 FIG. 21 SUPERSONIC FORCE MODEL Photograph of 1/23 scale model mounted on reflection plate in M.I.T. supersonic wind tunnel. Page 32 AVRO AIRCRAFT LIMITED - PROJECT 1794 5.1.1.2 (Cont'd) (iii) A 2/25 scale* air intake pressure recovery model. (Figs. 22 - 23). Broad conclusions from these tests are as follows: (i) The aircraft can be satisfactorily controlled and manoeuvred from engine idling to maximum thrust at supersonic speed through a satisfactory supersonic flight envelope. (Figs. 24 and 25). (ii) The drag of the aircraft agrees quite closely with the estimate. (Fig 26). (iii) The supersonic cruising efficiency appears to be better than had been expected. (Fig. 27). (iv) The air intake pressure recovery is better than the estimate. (Fig. 28). Further tests with these models are seen to be required: (i) To obtain further confirmation of the aircraft drag with the air intake running full. (The evacuation system failed to operate to the planned capacity during the tests). (ii) To generally extend the scope of the data. Due to the restricted testing time a too abbreviated program had to be accepted. (iii) To carry out transonic tests on the sting mounted model. (Planned but not achieved due to detail test difficulties). 1 JUNE, 1956 Page 33 SECRET FIG. 22 AIR INTAKE AND GAS EXHAUST SYSTEM MODEL NO. 3/19 (32" Dia. Model) Schematic showing electric actuator, intake exhaust flow control shutters, pitot probes, and reflection plane support strut. FIG. 23 SUPERSONIC AIR INTAKE MODEL INSTALLED Photograph of model in tunnel. Pages 34-35 SECRET FIG. 24 PROJECT 1794 FLIGHT ENVELOPE 40,000' W = 20,000 LB Graph of n (g's) vs Mach No. (0.2 to 2.2) showing trim limitations for engine idling and max thrust. FIG. 25 PROJECT 1794 FLIGHT ENVELOPE 80,000' W = 20,000 LB Graph of n (g's) vs Mach No. (0.2 to 3.0). FIG. 26 PROJECT 1794 ZERO LIFT DRAG AND MACH NO. Graph of CD vs Mach No. (0 to 3.0) comparing original estimate, sting model test points, and overall measured drag. FIG. 27 PROJECT 1794 VARIATION OF MAXIMUM LIFT/DRAG RATIO WITH MACH NUMBER Graph of (CL/CD)MAX vs Flight Mach No. (1.0 to 2.5), showing peak L/D near 6.0 at Mach 2.0. FIG. 28 PROJECT 1794 INTAKE PRESSURE RECOVERY (P1/P0 vs Mach Number M_infinity 1.5 to 3.0) Shows upper and lower air intake recovery factors compared to isentropic total head. Pages 36-40 AVRO AIRCRAFT LIMITED - PROJECT 1794 5.1.1.2 (Cont'd) (iv) To develop the air intake boundary layer bleeding system. This is a simple cusp below the air entry; several shapes were tested with indication that considerable further improvement is possible. 5.1.1.3 A number of small scale tests was carried out in the contractor's 18" x 18" low subsonic and 8" x 11" supersonic open circuit tunnel (Figs. 29 and 30) as follows: - Preliminary subsonic transition characteristics (Fig. 31) - Preliminary subsonic jet-trim characteristics (Figs. 32, 33 and 34) - Preliminary supersonic jet-trim characteristics (Fig. 35) - Dynamic behaviour of rate and displacement stability models (Figs. 36 and 37) - Air intake internal flow model (Fig. 38 and 39) The preliminary tests were carried out on both half-plane and full models. The results were such as to justify the larger scale program which was then embarked upon, and no important conclusions not validated by the main program can be drawn. These tests have therefore not been reported in detail. Illustrations of the models appear in Figs. 31 through 39, as noted above. Numerous further preliminary and ad hoc tests on other small models will almost certainly be required as design and development proceeds. 1 JUNE, 1956 Page 41 SECRET Illustrations and diagrams of Avro internal test facilities and models: - FIG. 29: Avro Ejector Wind Tunnel (Subsonic Installation Shown) - FIG. 30: Installation of Supersonic Liner in Avro Subsonic Ejector Wind Tunnel (8" x 11") - FIG. 31: Air Cushion Effects Model No. 1/1/1 (10" Dia. Model with Swash Plate Control) - FIG. 32: Stability and Control Models No. 2/3/4, 2/3/8 and 2/3/9 (Edge profile variations) - FIG. 33: Stability and Control Model No. 2/2/4 (20" Dia. Model) - FIG. 34: Stability and Control Model No. 2/4/1 (10" Dia. Model) - FIG. 35: Stability and Control Models No. 2/5, 2/6 and 2/7 - FIG. 36: Stability and Control Model No. 2/3/3 and 2/3/10 (With Two Degrees of Freedom & Gyro Control) - FIG. 37: Stability and Control Model No. 2/3/12 (With Two Degrees of Freedom) - FIG. 38: Air Intake and Gas Exhaust System Model No. 3/17/1 and 3/17/2 - FIG. 39: Internal Flow Intake Model Photograph Pages 42-52 AVRO AIRCRAFT LIMITED - PROJECT 1794 5.1.1.3 (Cont'd) Dynamic models (Figs. 36-37) showed static stability over a satisfactory angle of attack range. Damping was poor due to restraint. The rate model could easily be controlled with additional pitch damping from jets. Air intake internal airflow model (Figs. 38-39) showed satisfactory static pressure recovery and flow distribution, but forward flight flow distribution was unsatisfactory at the sides. Larger scale tests are required. 5.1.2 Air Cushion Effect Tests Apart from the 1/6th scale subsonic model tests (Page 20) two series of tests have been carried out at Malton on a static rig: - First series (Figs. 40-41) on 10" diameter models. - Second series (Figs. 42-43) on 20" diameter models (four times area and mass flow). Delta shape with peripheral jet (Fig. 44), wing-around-jet configuration (Fig. 45), and hot central exhaust were also tested. 1 JUNE, 1956 Pages 53-54 SECRET - FIG. 40: Air Cushion Effects Model No. 1/8 (Rig and model details) - FIG. 41: Model No. 1/8 Configurations Tested (Table and geometry keys) - FIG. 42: Air Cushion Effects Model No. 1/9 (20" Dia. Model) - FIG. 43: Air Cushion Effects Model No. 1/9 (Continued, with low pressure turbine exhaust and intake configurations) - FIG. 44: Air Cushion Effects Model No. 1/26/1 (Triangular/Delta Model 11.22" Sides) - FIG. 45: Air Cushion Effects Models No. 1/12 (Circular 8.80" Dia.) and 1/13 (Triangular 9.21" Sides) Pages 55-62 AVRO AIRCRAFT LIMITED - PROJECT 1794 5.1.2 (Cont'd) Broad conclusions: (i) Very little scale effect on the ground cushion. (ii) Lift augmentation extends at high level to between 45% and 60% span; up to 1.8 times jet thrust recorded at 45% span height. Falls off rapidly above this to 50-60% jet thrust in free air (restorable by local perimeter shuttering). (iii) Moderate parameter changes (jet angle, aspect ratio, lower intake/exhaust shape) do not drastically change general cushion characteristics. FIG. 46 PROJECT 1794 EFFECT OF LOWER INTAKE SUCTION ON GROUND CUSHION EFFECT Graph showing Lift/Jet Reaction (0 to 2.0) vs Height Above Ground (0 to 0.80 spans) for 20" Dia. Plenum Model, comparing peripheral jet only vs with intake suction. 1 JUNE, 1956 Pages 63-64 AVRO AIRCRAFT LIMITED - PROJECT 1794 5.1.3 Stability and Control Tests: Tests confirmed requirement for transonic force model and response rig tests. - FIG. 47: Shutter Test & Oscillation Rig Photograph (Page 66). 5.1.4 Air Intake and Gas Exhaust System Test: - 5.1.4.1 45° Full Scale Segment Test (Figs. 48-49): Intermediate research vehicle segment tested for diffuser efficiency and duct behavior. - 5.1.4.2 Thrust Recovery Test (Figs. 50-51 at Nobel facility): Evaluated jet exhausting at right angles to supersonic stream; recovered ~60% thrust in stream direction and showed moment augmentation of 1.8. - 5.1.4.3 End Loss Test (Fig. 52): Evaluated 90° bend nozzle losses. 5.1.5 Performance Tests: Evaluated via wind tunnel drag data. 5.1.6 Radial Flow Feasibility: Propulsion system analyzed. 5.2 Design Study and Theoretical Analysis: - 5.2.1 Ground Effect: Theoretical flow models matched general curve form. - 5.2.2 Stability and Control Analysis: Analyzed longitudinal/lateral equations (1st and 2nd order), response times, and hovering control. Confirmed feasibility without gyroscopic reactions due to contra-rotating impellers. - 5.2.4 Aircraft Performance: Mach 3.0+ capability substantiated. - 5.2.5 Radial Flow Feasibility: Tracing design evolution from 3-Viper ducted fan (Fig. 53), 4 Rolls-Royce RB.108 vertical layout (Fig. 54), inverted RB.108 layout (Fig. 55), to the final 6-Viper horizontal layout (Fig. 4). Pages 65-78 AVRO AIRCRAFT LIMITED - PROJECT 1794 FIG. 56 V.T.O. EFFICIENCY CHART Graph of Lb/Sec Airflow in Jet (0 to 4,000) vs Horse Power (0 to 30,000) and Fuel Consumption in Gal/Hr for four methods of obtaining 12,000 lb vertical lift: 1. Conventional Helicopter (~200 mph limit) - 85 gal/hr, ~2,000 HP 2. Convertaplane (Turbo-Contra-Prop, ~500 mph limit) - 660 gal/hr, ~7,500 HP 3. Ducted Fan Ramjet (Project 704, 2,000-2,500 mph) - 1,780 gal/hr, ~18,000 HP 4. Direct Jet-Lift Gas Turbine (1,500 mph) -Extravagant HP/fuel consumption Rocket lift shown at extreme right. Page 86 PROJECT 1794 6. TABULATED LABOUR & COST SUMMARY (Period July 1, 1954 to June 1, 1956) Summary of Manhours and Costs (Contract Period April 2, 1955 - June 1, 1956): - Air Cushion Effect & Test: 4,272.50 manhours | $24,528.99 - Stability & Control Analysis & Test: 57,855.00 manhours | $324,932.38 - Air Intake & Gas Exhaust System Test: 11,117.00 manhours | $62,117.07 - Airplane Performance Analysis & Test: 3,379.50 manhours | $17,399.07 - Radial Flow Engine Feasibility: 4,097.25 manhours | $24,920.26 TOTAL Contract Period: 80,721.25 manhours | $453,897.77 Together with Anticipatory Period ($287,921.22), Aggregate Total = $741,818.99. Balance remaining at end of May 1956: $19,824.00 (adequate for remaining report production). (Includes detailed Tabulated Labour and Cost Summary tables and cumulative expenditure/manhour Charts 1 through 6). Pages 87-95 AVRO AIRCRAFT LIMITED - PROJECT 1794 7. DEVELOPMENT AND PRODUCTION ASPECTS Project 704 is much simpler to manufacture than conventional aircraft and can be produced at lower cost. Due to circular symmetry, it uses a large number of identical detail parts. The airframe is broken down into six identical segments (each containing one Viper engine) built in the same jig, constituting ~90% of the airframe. Development plan envisages constructing a single research prototype in the shortest time for initial "cold" unaugmented test flying (proving vertical takeoff, ground cushion transition, and low subsonic handling). Outer combustion will be added subsequently for supersonic testing up to Mach 1.74 (limited by Viper engines). Full potential (Mach 3-4) to be realized in subsequent steel-structure prototypes. 1 JUNE, 1956 Pages 96-97 PROJECT 1794 8. NEW PROGRAMS REQUIRED & 9. TABULATED SUMMARY & COST FORECAST Proposed follow-on program (18-24 months duration): 8.1 Test Program: - 8.1.1.1 Supersonic Tests & Analysis (M.I.T. Tunnel, 60 hrs): $86,000.00 (combined with sting) - 8.1.1.2 Transonic Tests & Analysis (1/12th scale model, WADC 10 ft tunnel, 200 hrs): $223,000.00 - 8.1.1.3 Subsonic Tests & Analysis (1/6th scale model, WADC 20 ft tunnel, 200 hrs): $135,000.00 - 8.1.1.4 Internal Air Intake Flow Model (1/5th scale, WADC 10 ft tunnel, 50 hrs): $115,000.00 - 8.1.1.5 Small Scale Wind Tunnel Tests (Avro tunnels) - 8.1.2 Ground Effect Tests (20" scale model on new static rig): $52,000.00 - 8.1.3 Internal Flow Tests: - 8.1.3.1 Static 1/5th scale intake suction test: $75,000.00 - 8.1.3.2 Static 1/3rd scale nozzle end loss test: $68,000.00 - 8.1.3.3 Single engine intake & exhaust tests: $66,000.00 - 8.1.4 Propulsion System Test & Qualification (Full scale 6-Viper test rig, inner wing structure, test site & stand): $1,570,000.00 (Excl. tooling) - 8.1.5 Control System Development & Qualification: - 8.1.5.1 Oscillation rig and shutter box: $120,000.00 - 8.1.5.2 Outer wing segment & control system on 6-Viper rig: $216,000.00 (Excl. tooling) - 8.1.6 Combustor System Development (Rig at Nobel facility): $200,000.00 8.2 Design Study and Theoretical Analysis: - 8.2.1 Weapon System Design Studies (Reconnaissance, Interceptor, Tactical Bomber): $70,000.00 - 8.2.2 Weapon System Development Plan (Reconnaissance prototype per ARDC M80-4): $94,000.00 - 8.2.3 Stability and Control Analysis: $39,000.00 - 8.2.4 Propulsion System Analysis: $39,000.00 TOTAL COST FORECAST: $3,168,000.00 1 JUNE, 1956 Pages 98-112