Avro Canada VZ - 9 Avrocar The Avro Canada VZ - 9 Avrocar was a VTOL aircraft developed by Avro Aircraft Ltd . ( Canada ) as part of a secret U . S . military project carried out in the early years of the Cold War . The Avrocar intended to exploit the Coandă effect to provide lift and thrust from a single " turborotor " blowing exhaust out the rim of the disk - shaped aircraft to provide anticipated VTOL - like performance . In the air , it would have resembled a flying saucer . Originally designed as a fighter - like aircraft capable of very high speeds and altitudes , the project was repeatedly scaled back over time and the U . S . Air Force eventually abandoned it . Development was then taken up by the U . S . Army for a tactical combat aircraft requirement , a sort of high - performance helicopter . In flight testing , the Avrocar proved to have unresolved thrust and stability problems that limited it to a degraded , low - performance flight envelope ; subsequently , the project was cancelled in September 1961 . Through the history of the program , the project was referred to by a number of different names . Avro referred to the efforts as Project Y , with individual vehicles known as Spade and Omega . Project Y - 2 was later funded by the U . S . Air Force , who referred to it as WS - 606A , Project 1794 and Project Silver Bug . When the U . S . Army joined the efforts it took on its final name " Avrocar " , and the designation " VZ - 9 " , part of the U . S . Army ' s VTOL projects in the VZ series . Design and development . Origins . The Avrocar was the ultimate result of a series of blue skies research projects by designer " Jack " Frost , who had joined Avro Canada in June 1947 after working for several British firms . He had been with de Havilland from 1942 and had worked on the de Havilland Hornet , de Havilland Vampire jet fighter and the de Havilland Swallow aircraft , where he had been the chief designer on the supersonic research project . At Avro Canada , he had worked on the Avro CF - 100 before creating a research team known as the " Special Projects Group " ( more commonly known as SPG ) . Frost first surrounded himself with a collection of like - minded " maverick " engineers , then arranged for a work site . Initially ensconced in the " Penthouse " ( the derisive company nickname for the executive wing ) of the Administration Building , the SPG was subsequently relocated to a Second World War - era structure across from the company headquarters , the Schaeffer Building , that was secured with security guards , locked doors and special pass cards . At times , the SPG also operated out of the Experimental Hangar where it shared space with other esoteric Avro project teams . At the time , Frost was particularly interested in jet engine design and ways to improve the efficiency of the compressor without sacrificing the simplicity of the turbine engine . He found Frank Whittle ' s " reverse flow " design too complex and was interested in ways to " clean up " the layout . This led him to design a new type of engine layout with the flame can s lying directly outside the outer rim of the centrifugal compressor , pointed outwards like the spokes on a wheel . Power for the compressor was drawn from a new type of turbine similar to a centrifugal fan , as opposed to the more typical pinwheel - like design of conventional engines . The turbine drove the compressor using gearing , rather than a shaft . The resulting engine was arranged in the form of a large disk , which he referred to as a " pancake engine . " The jet thrust exited from around the entire rim of the engine , and this presented problems trying to adapt the design to a typical aircraft . Project Y . At the same time , the aircraft industry as a whole was becoming increasingly interested in VTOL aircraft . It was expected that any future European war would start with a nuclear exchange that would destroy most airbases , so aircraft would need to operate from limited airbases , roads or even unprepared fields . Considerable research effort was put into various solutions to securing a second - strike capability . Some of these solutions included rocket - launched aircraft like the zero - length launch concept , while many companies started work on VTOL aircraft as a more appropriate long - term solution . Frost felt the excellent performance of his new engine would be a natural fit for a VTOL aircraft due to its high expected power - to - weight ratio . The problem was how to use the annular thrust to drive the aircraft forward , as well as the problem of fitting the very large engine into a suitable airframe . Frost suggested using a series of vents to redirect the thrust flowing out of the " front " of the engine towards the rear , although it was well known that long channeling leads to a loss of thrust . In order to keep the " piping " as short as possible , the design ported the thrust out along the leading edge of what was essentially a very large delta wing . As the engine was disk - shaped , the triangular shape was " pushed out " near the front , producing a planform shaped roughly like a spade . For this reason the design was also referred to as the " Avro Ace , " a likely reference to the Ace of Spades . The compressor inlet was located at the middle of the engine , so the engine air intakes were located just to the front of the centre on the top and bottom of the aircraft . The cockpit was positioned over the main bearing , behind the intakes . A " spine " on the top and bottom ran from the cockpit area to the rear edge of the aircraft . Several other versions of the basic layout were also studied , including the " Omega " which was more disk - like as it cut away the rear portions of the delta wing as well . For VTOL operations the aircraft was expected to sit pointed up , supported by long landing legs that extended out of the spine . Landing would be accomplished at a very high angle , making visibility during the approach very difficult . A number of other VTOL experiments of the era attempted various solutions to this problem , including rotating pilots seats and cockpits , but none proved very effective . Another problem with various VTOL experiments was that stability in a hover was difficult to arrange , although not entirely unexpected . A solution to this problem would require the thrust to be directed downward from a larger area , as it is in a helicopter , where the lift is supplied over the entire area of the rotor disk . Most designers turned to bleeding off air from the engine ' s compressor , and directing that through pipes arranged around the aircraft . Frost ' s engine design used such a large number of nozzles that such an arrangement would not be to easy to build . In 1952 , the design was advanced enough that the Canadian Defense Research Board funded the effort with a $ 400 , 000 contract . By 1953 , a wooden mock - up of Project Y was completed , of which only images remain . It appears the project was considered too costly within the military establishment , which was at the time involved in several extremely expensive air defense projects . On 11 February 1953 , a story on the project was leaked to the Toronto Star along with images of the Omega design , apparently in order to gain further funding ( a strategy widely employed in the U . S . at the time , known as policy by press release ) . Five days later , the Minister for Defense Production informed the House of Commons that Avro was indeed working on a " mock - up model " of a flying saucer , capable of flying at and climbing vertically . Nevertheless , further funding was not forthcoming . Project Y - 2 : the " flat - riser " . While Project Y continued , Frost had meanwhile become interested in the Coandă effect , where fluid flows will follow strongly convex shapes , something that might be unexpected at first glance . Frost felt the effect could be used with his engine design to produce a more practical VTOL aircraft , the exhaust flowing outward over the upper surface of the aircraft and then being directed downward over a flap - like arrangement . This would produce a lift force around the entire edge of the aircraft , allowing it to land " flat " . He produced a number of small experimental designs using compressed air in place of an engine in order to select a suitable planform shape , and eventually decided that a disk was the best solution . As he continued these experiments , he found that the same thrust - direction system he intended for VTOL operations worked just as well for forward flight . In this case the disk shape was not of itself a good lifting surface , as it was neutral in terms of lift direction – that is , it would fly sideways as readily as it would fly forward . However , by modifying the airflow with the application of a small amount of jet thrust , the overall airflow over the craft could be dramatically altered , creating a sort of " virtual airfoil " of any needed configuration . For instance , by directing even a small amount of jet thrust down , a large mass of air would be pulled over the upper surface of the wing and dramatically augment the flow over the wing , creating lift . This appeared to offer a solution to one of the most vexing problems of the era , designing an aircraft that was effective at subsonic and supersonic speeds . Subsonic lift is created by the airflow around the wing following streamline s , but supersonic lift is generated by shock waves at points of critical curvature . No single design could offer high performance for both regimes . The blown disk could attack this problem by being laid out for supersonic performance only , and then using jet thrust to modify subsonic airflow into a semblance of a normal wing . The resulting design would be tuned for high supersonic performance , have reasonable subsonic performance , and would also offer VTOL , all in a single design . U . S . Involvement : Project 1794 / WS 606A . In late 1953 , a group of U . S . defence experts visited Avro Canada to view the new CF - 100 fighter jet . Somewhere along the way , Frost co - opted the tour and rerouted it to the Special Projects area where he proceeded to show off the Project Y mock - up and models and drawings ( some never before seen by senior company officials ) for a completely circular disk - shaped aircraft known as " Project Y - 2 . " The USAF agreed to take over funding for Frost ' s Special Projects Group , and a contract for US $ 750 , 000 followed in 1955 . By 1956 , Avro management was interested enough to commit $ 2 . 5 million to build a " private venture " prototype . In March 1957 , the Air Force added additional funding , and the aircraft became Weapons System 606A . A wide variety of designs were studied for a VTOL fighter aircraft , all revolved around the disk shape , leading to the Project 1794 involving a supersonic large disk fighter aircraft . The concept proceeded to wind tunnel testing with a variety of scale models . It featured a raised section in the middle over the engine , the intake covered with a series of louvers that would be closed in forward flight . Frost ' s performance estimates for the concept were for a potential of Mach 3 . 5 at altitudes . There was some debate about the concept within the USAF , as many groups were attempting to gain funding for their own pet projects , like nuclear powered bombers . In a repeat of the earlier Toronto Star release , in 1955 an extensive article appeared in " Look " magazine that , among other claims , speculated that current UFO sightings were Soviet - built saucers . The article went on to describe such an aircraft with diagrams that were clearly influenced by the Avro design . A new impeller - driven engine design was proposed as Avro PV - 704 ( PV stood for Private Venture ) , powered by six Armstrong Siddeley Viper jet engines blowing across the outer rim of a central rotor . The PV - 704 was a " stop - gap " design built into a bunker - like building behind the Avro Experimental Test facility . It was intended to test various Project 1794 concepts and provide the USAF with test data to show the viability of the concept . The original plan to initially test the " Viper Engine Rig " was to have continued into " free flight " testing . Unfortunately , testing was anything but smooth ; the test model suffered from hazardous oil leaks , resulting in three fires . It eventually got to the point that staff were afraid of the machine , even when safely ensconced in a booth constructed of bullet - proof glass and quarter - inch - thick steel . A final , disastrous and nearly lethal engine test in 1956 which involved a Viper jet engine " running wild " convinced Frost that a less dangerous test vehicle was necessary . Genesis of the Avrocar . To gather flight data on the basic concept while the engine development continued , in 1958 Frost proposed building a smaller " proof - of - concept " test vehicle he called the Avrocar . By this point , the U . S . Army was involved in a wide variety of experiments on smaller VTOL aircraft that would act as a " flying Jeep , " and they became interested in Avro ' s concept as well . Frost pitched his smaller design both as a prototype of a vehicle suitable for the Army ' s needs , as well as an aerodynamic testbed for the WS - 606 . Initial performance requirements for the Avrocar were a ten - minute hover capability in ground effect and range with a payload . The new plan appeared to make everybody happy , and a $ 2 million joint - services contract managed by the Air Force was awarded to Avro to build and test two Avrocars , which the Army referred to as the VZ - 9 - AV ( with AV standing for " Avro , " an unusual departure from normal U . S . Army nomenclature ) , the latest in a series of " VZ " aircraft . Army interest in the Avrocar program was apparently very high . Bernard Lindenbaum of the Air Force Flight Dynamics Laboratory recalls a trip to Washington in the late 1950s to request additional funding for a study on helicopter drag reduction . Although the funding was approved , he overheard an Army General remark that the Huey would be the last helicopter the Army would buy since the helicopter would be replaced by the Avrocar . Additional Air Force funding of approximately $ 700 , 000 ( unexpended from the 606A program ) was also moved to the Avrocar project . In March 1959 , an additional $ 1 . 77 million contract was received for a second prototype . At rollout , projected performance was far in excess of the requirement , with a maximum speed , ceiling , range with payload , and hover out of ground effect with payload . Maximum takeoff weight with transition to forward flight out of ground effect was calculated to be , maximum weight with a transition in ground effect ( GETOL ) was . Just as the first working test models were being manufactured , disaster struck . The Canadian government cancelled the Avro CF - 105 Arrow program on " Black Friday , " 20 February 1959 . The ensuing result was the lay - off of almost all Avro Canada employees , including those with the Special Projects Group . However , three days following the announcement of the Arrow cancellation , many of the Special Projects employees were rehired . But it wasn ' t quite business as usual . The team now included people from the CF - 100 and CF - 105 teams and the Special Projects Group was moved into the main building , which was nearly empty . As well , company " brass " became more involved in the group ’ s operations . The USAF Project Office devoted to the Avro projects , recommended that the WS - 606A and all related work ( including the Avrocar ) be cancelled . A " stop / go " work order came down and Frost was forced once more to try to rescue the project . In an elaborate effort , Frost made a resounding case for continuation of U . S . military funding . Late in May 1959 , the USAF authorized Avro to continue the " flying saucer " programs . Design . The Avrocar was a disk - shaped aircraft with the same basic shape as a frisbee , the upper surface of the disk being fairly curved , and the bottom much less so . The disk was in diameter and thick . The main structural truss was a large equilateral triangle , to which the various components were attached . The 124 - blade " turborotor " sat in the center of the triangle , with most of the rotor ' s thrust directed straight down through an opening in the lower surface , but some was bled off to power the control system running along the outer rim of the disk . Power for the rotor was provided by three Continental J69 - T - 9 jet engines attached to the truss . Each engine had its own fuel and oil tanks and other support systems , although it was expected these would be interconnected in future models . The majority of the airframe was made of aluminum with an empty weight of . Pilot control was entirely through a single side - mounted control stick . Pitch and roll were controlled through conventional fore - aft and side - to - side motions , while yaw could be controlled by twisting the stick . No mechanical linkages were used , the stick instead controlled the flow of high pressure air around the craft , which either directly attached to various control surfaces , or indirectly through local cable linkages to replace controls that were intended to be cable - actuated ( like throttle controls on the engines ) . The attitude / thrust control system consisted of a large ring situated outside of the main disk , shaped roughly like a rounded triangle with the flat surface on the " inside . " Viewing the craft from the side , the control flap is almost invisible , appearing in its neutral position to blend into the profile . The pilot ' s controls moved the ring in relation to the rest of the craft , affecting the airflow moving outward from the center of the craft . Vertical lift could be increased by moving the entire ring down , which would produce more airflow over its upper surface , which would then bend down over this surface toward the ground . Tilting the ring resulted in asymmetric thrust for directional control . It was discovered that the craft was inherently unstable in forward flight , as the aerodynamic center of pressure was well forward of the center of gravity . The Avrocar thus included a mechanical stability control system that was independent of the pilot ' s controls . The turborotor had a fairly large angular momentum and was intended to act as a powerful gyroscope , providing a " normal " direction of flight . Control cables attached to the base of the rotor would be pulled when the craft moved in relation to the rotor , actuating the control surfaces to counteract the motion . The vehicle was manned by a crew of two , positioned in separate cockpits squeezed into empty areas in the airframe . In practice , only one pilot was usually on board during testing ; a number of flights were made with an observer in the second cockpit . Until control problems were completely solved , the Avro test pilots acquired a " touch " for the extremely sensitive control inputs and Avro Aircraft Chief Development Test Pilot Potocki was eventually able to demonstrate a " hands - off " flight . Nonetheless , Avro test pilot Peter Cope , USAF project pilot Walter J . Hodgson and NASA Ames Chief Test Pilot Fred J . Drinkwater III , who all flew the Avrocar , considered it still a tricky vehicle to fly . Drinkwater likened a flight in it to " balancing on a beach ball . " The undercarriage of the Avrocar was rudimentary with three small castoring wheels mounted on " stub " shafts ; a set of skids was substituted later in testing although they were not normally fitted . Operational history . Testing . The first Avrocar , # " 58 - 7055 " , rolled out of the Avro Malton factory in May 1959 . From 9 June to 7 October 1959 , it was tested in a static hover rig . Unfortunately , hot gas from the exhaust was found to mix back into the intakes in hover , reducing engine thrust . In addition , the fan generated lift only from a small area of its surface , lowering overall thrust available . The ducts also proved to have higher losses than expected , and a series of modifications were not able to solve this problem to any large degree . These problems reduced maximum lift at higher altitudes out of the ground effect to , less than the empty weight of the aircraft at . This meant the aircraft would be incapable of hovering out of the ground effect . Following these tests , the vehicle was sent to NASA Ames for a wind tunnel testing . The second , # " 59 - 4975 " , was completed August 1959 . On 29 September , the first attempt to hover was made with the Avrocar tethered to the ground . After the vehicle became airborne , an uncontrollable roll and pitch - coupled oscillation started that forced each of the three wheels into the ground in turn . The pilot , W . D . " Spud " Potocki , immediately shut down all engines . Changes were made to the stability system to provide more control authority , while new tethers were investigated to improve the ability to control these sorts of problems . As testing continued it became clear that the problem was inherent to the design , and the engineers started referring to the effect as " hubcapping , " so - named as it appeared similar to a hubcap spun on the ground . Investigations into the effect revealed what was causing the problem . While in the ground effect , the high - pressure air under the craft was trapped , filling the entire area and thus providing a stable base . When the craft rose out of the ground effect , the air formed itself into a single narrow column , described by Frost as " tree trunking " . At intermediate altitudes the craft would momentarily transition from one regime to the other , during which time one side of the vehicle would be entirely supported while the support was disappearing under the other . This led to a strong pitching motion towards the unsupported side . As soon as this occurred that side would approach the ground and re - establish the supporting air , while the other side would then be raised above this limit . This process would repeat itself , with the craft rolling from side to side . Modifications were carried out in order to try to solve the problem . Eventually a series of 52 holes were drilled in the bottom of the vehicle , located radially three feet from the center . These were to provide a central jet to stabilize the ground cushion . With these modifications complete and apparently working , the first completely free flight occurred on 12 November 1959 . This test proved the nozzle control system unacceptable . The spoilers were intended to direct the air out over the top or bottom of the annular flap , out the bottom only during hover , but over the top and bottom during forward flight . The idea was that when the flap was positioned in order to provide control , the lift would be lowered on one side and raised on the other . Lift was indeed lowered on one side , but sadly the lift did not improve on the other , so every control input resulted in a loss of altitude . After five flights , testing was temporarily halted on 5 December 1959 , by which time the Avrocar had logged 18 . 5 hours of test time in total . A completely new design was installed over the winter . The original spoilers were removed and replaced by a single ring below the annular flap . The ring shifted in relation to the craft under control input , " sealing off " the gap on one side while opening it on the other . Tests continued in January 1960 , and appeared to work much better . However , while the new control system improved the hovering qualities , the craft now became unstable at higher speeds above . The first Avrocar at Ames was similarly modified , and , in April 1960 , it was tested in their 40 x wind tunnel . The problem became clear ; the ring blocked so much of the overall engine thrust that the overall power was greatly reduced . As the craft sped up , the airflow on the underside reduced the recirculation , reducing the lift due to airflow over the upper surface . This was somewhat unexpected ; recirculation had been considered a " bad thing " due to the loss of engine thrust , and its positive effects on lift do not appear to have been appreciated . In the end , in order to maintain lift at higher forward speeds the craft had to be pitched to the end of its control capability . Avro was convinced that the concept was still workable , and proposed a new program for major rework of the propulsion and control system . Instead of the single annular triangular flap and spoilers , or the later ring control , the new system included two separate control systems for hover and forward flight , combined into a single nozzle . For hover , a series of " transition doors " were opened into the nozzles , blocking them off and re - directing the flow downward under the aircraft . Control during this regime was provided by moving the outer portion of the flap to " focus " the flow . At higher speeds , the doors were closed , allowing the air to flow out from the edge of the aircraft , where a series of simple flap - like controls were located . The new control system covered the rear 3 / 4 ' s of the aircraft ' s outer circumference ; the front section featured the hovering controls only . Modifications were completed on the Ames model and testing resumed in April 1961 . The new design demonstrated much better control in hover and considerably improved lift . The vehicle was now able to travel at up to , a great improvement over the previously reached . However , it remained unstable in pitch , and exhibited a strong nose - up trim . NASA engineers attempted to modify this with a T - tail , but this proved to sit within the airflow of the turborotor and did not help . Frost ' s team considered two new designs , one with a large vertical tail and one with a wing with tip mounted verticals — " winglets . " Both designs used two thrust General Electric J85 turbojets and increased the turborotor diameter from five to six ft . On 9 June 1961 , a second USAF / NASA flight evaluation of the Avrocar was conducted on the similarly modified second prototype at the Avro facility . During these tests , the vehicle reached a maximum speed of and showed the ability to traverse a ditch six feet across and deep . Flight above the critical altitude proved dangerous if not nearly impossible due to inherent instability . The flight test report further identified a range of control problems . Cancellation . Before modifications could be achieved , funding ran out in March 1961 . Frost ' s proposals for a modified design were not accepted , and the Avrocar and related WS - 606A supersonic VTOL programs were officially cancelled in December 1961 by the U . S . military . Avro company executives encouraged additional VTOL research projects , exploring new configurations married to a disk platform and even a " lift jet " version , but no further interest resulted from Canadian or other sources , to cap the end of this Special Projects Group program . In 1961 , a number of later proposals , including the Avro P470 VTOL fighter concept derived from the Special Projects Group , were submitted to fulfill a NATO competition for a tactical strike fighter . These needs were filled by the Hawker Siddeley Harrier , but in more general terms , interest in VTOL faded as it became widely believed a nuclear first strike would not be used at the start of a European war . The second Avrocar had logged about 75 flight hours at the end of the flight testing . Judged by its performance , the Avrocar was an abject failure : it couldn ' t lift itself safely more than a few feet off the ground , and its bulbous design limiting high - speed performance accompanied by unbearable heat and screaming exhaust noise , made it impractical for the military . Although considered a technical failure , its design would be prophetic : it was a rubber skirt shy of being one of the world ' s first hovercraft , the Saunders Roe SR . N1 also taking off in 1959 . Nevertheless , company designer , John Frost applied for a number of patents in Canada , the UK and the U . S . that established the pivotal role that the Avrocar and related Avro experimental vehicles , made in the VTOL world . Latest developments . The Avro VZ - 9 Avrocar was a " dead end " in VTOL design , according to Russell Lee , curator at the National Air and Space Museum , yet its technological innovations have intrigued other designers . One of the design elements it embodied , the use of ducted fans led to other experimental programs . Dr . Paul Moller , a Canadian expatriate who had worked at Avro Canada as a young engineer , based an initial series of experimental VTOL vehicles on " saucer " technology utilizing the buried ducted fan à la - Avrocar . The XM - 2 , the first of the series looked remarkably like a miniature flying saucer . After successful tether tests , the saucer designs also at one time publicized as " discojet " were abandoned and their latest project , the Moller Skycar , has a flying - car appearance . The Avrocar story did not end with the termination of the program . Only two Avrocars were ever produced and because the U . S . military had paid for the work , they reverted to U . S . ownership at the end of the program . The second example , S / N " 59 - 4975 " , utilized for " flight " testing , returned to Canada briefly for display in Montreal at the " Man and His World Exhibition " ( 1968 ) ; after a lengthy period of outdoor display , it is now under restoration at the U . S . Army Transportation Museum in Fort Eustis , Virginia . The first Avrocar , S / N " 58 - 7055 " ( marked " AV - 7055 " ) , after tethered testing , became the " wind tunnel " test model at NASA Ames , where it remained in storage from 1961 until 1966 , when it was donated to the National Air and Space Museum , in Suitland , Maryland . There it continued gathering dust for the next forty years . The Museum finally scheduled it for restoration and display at their newly constructed Steven F . Udvar - Hazy Center . Instead the Avrocar has been loaned to the National Museum of the United States Air Force in Dayton , Ohio , arriving in November , 2007 . After a full restoration , which included fabrication of both missing plexiglass bubbles , it was put on display in June 2008 in the Museum ' s Cold War Gallery . It has since been moved to the Presidential Aircraft Gallery . A full - scale replica of the Avrocar was prepared for the 2002 production , " Avrocar : Saucer Secrets from the Past . " It now resides as an exhibit at the Western Canada Aviation Museum , Winnipeg , Manitoba , Canada .