PROJECT 1794 FINAL DEVELOPMENT SUMMARY REPORT USAF Contract No. AF33 (600) 30161 AVRO A/SRCRAFT LIMITED Declasstied on June 14, 2001 by the ArrForce Declassication fice IAW EO 12958 Declasstfied SECURITY WARNING This document is intended solely for the recipient and such persons as have been connection transmission, unauthorized retention, destruction, revelation tents, in any manner, to (an) unauthorized person(s) is forbidden. instructions infraction This copy has been issued by Avro Aircraft Limited, Malton. Declassitied iw Senne 15988 Declasstied TABLE OF CONTENTS 1. SUMMARY 1 2. INTRODUCTION 2 3. PROGRESS OF THE DESIGN 3 4.1 Description 8 4.2 Operation 11 4.3 Performance 15 5. DISCUSSION OF ACTIVITIES 20 5.1 Test Results 20 5.2 Design Study & Theoretical Analysis 74 6. FINANCIAL STATEMENT 87 ithe DEVELOPMENT AND PRODUCTION ASPECTS 96 8. NEW PROGRAMS REQUIRED 98 8.1 Tests Program 98 8.2 Design Study and Theoretical Analysis 103 9. TADULATED SUMMARY & COST FORECAST 110 Declassitied 1 JUNE, 1956 -SEGREF Declasstied PROJECT 1794 FINAL DEVELOPMENT SUMMARY REPORT USAF Contract No. AF33(600)30161 Issued by: Avro Aircraft Limited Malton, Ontario, Canada Approved by: ~C.M. Frost H.C. Moody Chief Design Engineer Engineering Manager Special Projects Group Special Projects Group Avro Aircraft Limited. Avro Aircraft Limited. The number of pages in this report, including the Title, Table of Contents and Illustration sheets is 114 Declassified I.D. No. 56-RDZ-19954 1 JUNE, 1956 SEGREF AVRO AIRCRAFT L1M17TE: Unclasstied he PROJECT 1794 FINAL DEVELOPMENT 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 air- craft, 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. Unclassified AVRO AIRCRAFT L1M1ITED Unclassified PROJECT 179 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", ofa new type proposed by AVRO AIRCRAFT LIMITED: together with substan- tiating tests. This contract is essentially a feasibility study and "design configuration effort shall be confined to the minimum required for demon- stration 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 develop- ment summary report. The whole period is covered by this final develop- ment 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 TUNE, 1956 Unclassified 2 AVRO AIRCRAFT LIMNNTED Unclassified PROJECT 1794 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 plan- form, 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. Unclassified Unclassified $8000 3HVINI UY 44O-3IVL \YaEy 31ZZ0N ONMOAINOD SHALINHS ONIONS sanvi wand Unclassified Unclassified FIG. 2 INTERMEDIATE RESEARCH AIRCRAFT Unclassified Unclassified Unclassified Unclassified PROJECT 1794 TANVd SSADDV INIONI SYFLINHS TOWLNOD LHOITS Unclassified Unclassified AVRO AIRCRAFT LIMmTED C PROJECT 1794 4, PROJECT 704 distinguish undertaking Project 704. 4.1 Description approximately turbo-jets exhausting generators contra-rotating centrifugal impellers, comparison conventional centrifugal turbo-jets, statically Unclassified Unclassified AVRO AIRCRAFT LIMITED PILOT'S COCKPIT UPPER IMPELLER AND TURBINE UPPER AND LOWER INTAKES INTEGRAL FUEL TANKS FLAME HOLDERS ON Ree ENGINE INTAKE OUTER WING - = FLIGHT CONTROL SHUTTERS INNER WING DIFFUSER SECTION / TURBINE EXHAUST \ 6 A.S.M. VIPER 8 ENGINES LOWER IMPELLER AND TURBINE ENGINE TAILPIPE SECTION A-A PLAN VIEW AND SECTION THROUGH AIRCRAFT Unclassified Unclassified <i PROJECT 1794 AVRO AIRCRAFT LinmTeo ENGINE INSTALLATION - ASM. VIPER 8 ENGINE ENGINE INTAKE AND SSS INTAKE CASCADES a Unclassified 10 AVRO AIRCRAFT LIMITED Unclassified Cee PROJECT 1794 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 dia- phragm 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. To take off, all the shutters on top of the wing are closed and shutters]1] Unclassified Unclassified AVRO AIRCRAFT LIMITED PROJECT 1794 XO8 ONILNNOW Sadid C334 Unclassified TOULNOD WIM Liv 2 3uOd & JAIVA ONIIEW AIVLLV JO JIONV TOULNOD WIL wIGIOH aWV14 AVRO AIRCRAFT LIMNTED Unclassified fi. PROJECT 1794 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 pro- duces 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 flam 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 1 JUNE, 1956 Unclassified @ Unclassified Ce AVRO AIRCRAFT LIMITED Cc PROJECT 1794 FIG. 8 GROUND CUSHION EFFECT 14 Unclassified @ Unclassified tii: 4.2 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 collec- tively 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 sum- mary assumes this restriction has been removed: At 1200K main combustion temperature, Max. level speed (Fig 9) Mach B.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 Unclassified Unclassified ~r 4,3 Take-off and landing VTOL Unclassified Unclassified AVRO AIRCRAFT LIMITED LB. THRUST AT 2240F DRAG AND THRUST > TOTAL NET DRAG 6-VIPER ENGINED 10 FLIGHT MACH No. 2 = PROJECT 1794 DRAG AND THRUST vs MACH NO. Unclassified Declasstied 90, 000 AIRCRAFT WEIGHT = 21700 lb AIRCRAFT WEIGHT RATE OF CLIMB FT/SEC, Declasstied FIG, 10 PROJECT 1794 RATE OF CLIMB AT MACH 2, 26 Declasstied SATIN TVOILNVN AONVU G22@ HOWW LV WITS OINOS& Declassiied -SEERET- Unclassified =e AVRO AIRCRAFT LIMITED ( . PROJECT 179 5. DISCUSSION OF ACTIVITIES 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 Development lating air illustration photographs associated equipment. of subsonic operation, tests with transition 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 thickness/chord Corrections performance the difference. Unclassified Declassitied Unclassified AVRO AIRCRAFT LIMNTED FIG.13 1/6 SCALE S Unclassified ONIC MODEL Unclassified AVRO AIRCRAFT LIMNTED PROJECT 1794 Unclassified Unclassified AVRO AIRCRAFT LIMITED PROJECT 1794 Unclassified er PROJECT 1794 AVRO AIRCRAFT LimmTroa 5.2.22 Because of the large number of variables - speed, transition con- trol, 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 cC 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 inthe very low speed range andno data wastaken 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 Unclassified Declassified ud WALNAWOW ONIONGOYd) ONTICI ANIONA 1WTO9 0 XV NOILVLINIT LINIT WINL rH | | | rH FL FIG. 16 PROJECT 1794 FLIGHT ENVELOPE S.L, AIRCRAFT WEIGHT = 20000 LB Deciassfed -SEERET wo |als frs AVRO AIRCRAFT LinmTeo S, lake 2 Unclassified ie PROJECT 1794 accuracy data would be regarded as valuable confirmation of the transition flight path. (ii) To investigate the surface pressure distribution on the air- craft in various flight conditions. (iii) To investigate control scheme modification to improve trans- ition control characteristics through the whole angle of