Misplaced Pages

#36963

53-613: Before the Second World War, the British aircraft manufacturer Saunders-Roe (often known as Saro) had initiated plans for transatlantic seaplanes. In 1939 the firm planned a machine of 85 to 90 tons, but the start of the war altered priorities. When Saro resumed in 1943, the studies had grown to 150 tons and ultimately became the Saunders-Roe Princess , of which only three were built. Despite this failure, Saro

106-583: A 214-foot wingspan, a height of 55 feet 9 inches, and a length of 148 feet. The proposed aircraft would be capable of a cruising speed of 340 MPH at an altitude of 37,000 feet, a range (dependent on payload) of 5,190–3,640 miles, and be outfitted with luxurious accommodation for a total of 104 passengers. During 1945, in response to an approach made by the British Ministry of Supply , which had been seeking design submissions from aviation companies for an envisioned new long range civil flying boat, which

159-469: A long range aeroplane would be required to carry a large load of fuel, a larger size of the aircraft could be permitted without needing to cater for factors such as limited runway and airfield sizes. In addition, for services to far-flung parts of the British Empire, the ability to land and take-off from any available area of water was a distinct advantage for services to such places, many of which at

212-425: A more revolutionary flying boat. During 1943, the chief designers of Saunders-Roe and Short had collaborated to produce a preliminary design specification for an innovative large flying boat. This design specification defined various criteria for the proposed aircraft, which would be the largest all-metal flying boat ever built; performance criteria included a weight of 140 tons, a pressurised 'double-bubble' hull,

265-403: A part of the servo-powered control system were to fail, a faulty section could be "trailed" so that it did not act against the remaining working sections. While the prototype aircraft had been fitted with advanced (but conventional) hydraulic controls, Saunders-Roe had intended production aircraft to use an analogue system featuring electrical servos with hydraulic final control actuators. Such

318-437: A rounded, bulbous, "double-bubble" pressurized fuselage which contained two full passenger decks ; these decks had sufficient room to accommodate up to 105 passengers in great comfort. The planing bottom of the hull had only a slight step in the keel to minimize drag in the air. The Princess was powered by an arrangement of ten Bristol Proteus turboprop engines. These engines drove six sets of four-bladed propellers ; of these,

371-489: A system had been built and undergone ground-testing, but the Princess had been terminated prior to any aircraft having been fitted with the system. Data from Saunders and Saro Aircraft since 1917 British Flying Boats and Flight 1952 General characteristics Performance Related development Aircraft of comparable role, configuration, and era Related lists Jet propulsion Jet propulsion

424-581: A total of 47 test flights, including two public appearances at the Farnborough Airshow . This work was carried out under a development contract for the Ministry of Supply , the intention being that this would lead to a contract for the aircraft from British flag carrier British Overseas Airways Corporation (BOAC). Although the initial development contract had been successfully met, BOAC eventually decided to focus on its land-based routes using

477-447: Is dimensionally equivalent to the generated thrust divided by the propellant mass flow rate or weight flow rate. If mass ( kilogram , pound-mass , or slug ) is used as the unit of propellant, then specific impulse has units of velocity . If weight ( newton or pound-force ) is used instead, then specific impulse has units of time (seconds). Multiplying flow rate by the standard gravity ( g 0 ) converts specific impulse from

530-466: Is also used by several marine animals, including cephalopods and salps , with the flying squid even displaying the only known instance of jet-powered aerial flight in the animal kingdom. Jet propulsion is produced by some reaction engines or animals when thrust is generated by a fast moving jet of fluid in accordance with Newton's laws of motion . It is most effective when the Reynolds number

583-546: Is high—that is, the object being propelled is relatively large and passing through a low-viscosity medium. In animals, the most efficient jets are pulsed, rather than continuous, at least when the Reynolds number is greater than 6. Specific impulse (usually abbreviated I sp ) is a measure of how effectively a rocket uses propellant or jet engine uses fuel. By definition, it is the total impulse (or change in momentum ) delivered per unit of propellant consumed and

SECTION 10

#1732786955037

636-493: Is produced by ejecting water through a siphon , which typically narrows to a small opening to produce the maximum exhalent velocity. The water passes through the gills prior to exhalation, fulfilling the dual purpose of respiration and locomotion. Sea hares (gastropod molluscs) employ a similar method, but without the sophisticated neurological machinery of cephalopods they navigate somewhat more clumsily. Some teleost fish have also developed jet propulsion, passing water through

689-481: Is the propulsion of an object in one direction, produced by ejecting a jet of fluid in the opposite direction. By Newton's third law , the moving body is propelled in the opposite direction to the jet. Reaction engines operating on the principle of jet propulsion include the jet engine used for aircraft propulsion , the pump-jet used for marine propulsion , and the rocket engine and plasma thruster used for spacecraft propulsion . Underwater jet propulsion

742-661: The British Empire which had previously not been served at all, passengers were transported within an unprecedented level of comfort, being provided with luxurious first class accommodation, including a promenade , sizable galley , separate bathrooms for men and women, and individual cabins for passengers. However, operations of these flying boats had been disrupted by wartime, during which Imperial Airways had also merged with British Airways Ltd to form British Overseas Airways Corporation (BOAC) in 1940. While restricted operations of commercial flying boats did continue, such as

795-445: The "effective exhaust velocity". This is higher than the actual exhaust velocity because the mass of the combustion air is not being accounted for. Actual and effective exhaust velocity are the same in rocket engines not utilizing air. Specific impulse is inversely proportional to specific fuel consumption (SFC) by the relationship I sp = 1/( g o ·SFC) for SFC in kg/(N·s) and I sp = 3600/SFC for SFC in lb/(lbf·hr). From

848-737: The Princess was shared with the United States Navy , who were at the time examining the possibility of converting the three stored aircraft to make use of nuclear power . This interest resulted in a delegation from Saro being dispatched to the US to discuss a sale of the preserved Princesses. However, this interest ultimately amounted to nothing. In 1964, the three Princesses were all purchased by Eoin Mekie on behalf of Aero Spacelines , who planned to use them as heavy-duty freight aircraft for transporting Saturn V rocket components for NASA . When

901-480: The Proteus engine, once perfected, would be capable of enabling the type to achieve its envisioned performance figures. G-ALUN was the only model to fly, performing 46 test flights in total during which 100 hours flight hours were accumulated. Princess Air Transport Co Ltd was formed with the object of studying the factors affecting the operation of the Princess flying boats and to tender for their operation should

954-663: The ability for the aircraft to conduct a water landing would also be advantageous for proximity landing at sea, or on nearby lakes in Florida . Ultimately, this plan was deemed to be impractical, though the existing Guppies continued to function throughout the Apollo program as efficient air transport of the outsize hardware used in these missions. Conroy quipped that the British were "offended when we named our aircraft 'The Pregnant Guppy'. Man, can you imagine what they would have said if we produced 'The Pregnant Princess' !" They were

1007-514: The air, or in the case of a nuclear rocket , heats an inert propellant (such as liquid hydrogen ) by forcing it through a nuclear reactor . Plasma thrusters accelerate a plasma by electromagnetic means. The pump-jet, used for marine propulsion , uses water as the working fluid, pressurized by a ducted propeller , centrifugal pump , or a combination of the two. Cephalopods such as squid use jet propulsion for rapid escape from predators ; they use other mechanisms for slow swimming. The jet

1060-535: The aircraft to be outfitted with some form of powered flight controls , including an early fly-by-wire implementation, in order that pilots would be able to effectively actuate its large control surfaces, which would have to overcome equally larger forces. However, it was decided to opt for a traditional mechanical linkage approach that was augmented by a series of electrically driven power assist units to effectively support actuation instead. The ailerons and rudder were split into multiple sections in order that, if

1113-558: The aircraft, it was found that corrosion had set in while in storage. As a result, all three aircraft prototypes were subsequently scrapped. Before the Second World War , British airline Imperial Airways had successfully used large long-range passenger flying boats such as the Short Empire and Short S.26 to build up a network of long-distance routes. These flying boats had not only pioneered new aerial routes across

SECTION 20

#1732786955037

1166-526: The airline presently had no need for the Princess, or any new large flying boat. The airline had already elected to terminate its existing flying boat services during 1950. In late 1951, it was announced that construction of the three Princesses would proceed with the intention of using them as transport aircraft in RAF service. However, in March 1952, it was announced that while the first prototype would be completed,

1219-521: The cocooning was removed, it was found that they were badly corroded (the contract for maintenance and inspection of the stored aircraft had been allowed to lapse, which resulted in the airframes deteriorating rapidly), and all three Princesses were broken up by 1967. In the wake of the success of his Pregnant Guppy , constructor Jack Conroy discussed his concepts for other outsize transports with Air Progress in their publication, World's Greatest Aircraft (Petersen Publications, 1973). Conroy considered

1272-404: The compressors and turbines, depending instead on the dynamic pressure generated by the high speed (known as ram compression). Pulse jets also omit the compressors and turbines but can generate static thrust and have limited maximum speed. The rocket is capable of operating in the vacuum of space because it is dependent on the vehicle carrying its own oxidizer instead of using the oxygen in

1325-598: The creation of an outsize transport from the Princess to have been basically feasible, in that it shares a sectional 'double-bubble' fuselage construction similar to that of the Boeing 377 Stratocruiser , on which the Guppies were based. The reason for considering producing such an aircraft was the desire of NASA to possess a means of transporting first stage of the Saturn V rocket by air, if this were possible, to Cape Canaveral ;

1378-480: The definition of specific impulse thrust in SI units is: where V e is the effective exhaust velocity and m ˙ {\displaystyle {\dot {m}}} is the propellant flow rate. Reaction engines produce thrust by expelling solid or fluid reaction mass ; jet propulsion applies only to engines which use fluid reaction mass. A jet engine is a reaction engine which uses ambient air as

1431-417: The excellent conditions present on the day. The prototype was quickly put through several test flights with the hope of being able to sufficiently ready the flying boat to appear at the 1952 Farnborough Airshow , however indications of engine reliability issues were encountered and this led to the intended flight display at Farnborough that year being abandoned. As further testing of the prototype continued,

1484-401: The fate of the programme. In addition to the prototype, a further two Princesses ( G-ALUO and G-ALUP ) were under construction, but these would never fly. While a decision from the government was pending, the three aircraft were placed into storage, being cocooned and retained, one at Cowes and two at Calshot Spit ; it had been hoped that work on the programme would be restarted when a buyer

1537-532: The flying boat's viability within the House of Commons , which was being increasingly regarded as a high-risk initiative with unreliable costing. Specifically, designing and testing of the airframe, as well as the independently conducted development of the Proteus engine to power the SR.45, had been major contributors to the higher-than-expected costs. In 1951, BOAC re-evaluated its standing requirements, and determined that

1590-414: The gills to supplement fin-driven motion. In some dragonfly larvae, jet propulsion is achieved by the expulsion of water from a specialised cavity through the anus. Given the small size of the organism, a great speed is achieved. Scallops and cardiids , siphonophores , tunicates (such as salps ), and some jellyfish also employ jet propulsion. The most efficient jet-propelled organisms are

1643-525: The inner four propellers were double, contra-rotating propellers which were driven by a twin version of the Proteus, named the Bristol Coupled Proteus , each engine drove one of the propellers. The two outer propellers were single and each powered by a single engine. The cockpit of the Princess was designed to be operated by a pair of pilots, two flight engineers , a navigator , and a radio operator . Early on, it had been intended for

Saunders-Roe Queen - Misplaced Pages Continue

1696-431: The jet-powered De Havilland Comet instead. The era of the large flying boat had effectively ended prior to the aircraft's completion. Work on the Princess was ultimately cancelled after having produced three examples, only one of which flew. By the mid-1950s, large commercial flying boats were being increasingly overshadowed by land-based jet airliners . Factors such as runway and airport improvements had added to

1749-523: The last fixed-wing commercial aircraft produced by Saunders-Roe. The company constructed one more fixed-wing design, the Saunders-Roe SR.53 mixed-power (rocket and turbojet) fighter design; aside from that venture, the company primarily concentrated its efforts on helicopters and hovercraft after this point. The SR.45 Princess was a large flying boat, being the largest all-metal flying boat to have ever been constructed. The Princess featured

1802-430: The leading edge of the wing during flight, and another set of intakes on the top of the wing while on the water. Water rudders facilitated manoeuvring on the water. Neither P & O nor the government were willing to finance the project, it did not go beyond the stage of the drawing board. Data from General characteristics Performance Saunders-Roe Princess The Saunders-Roe SR.45 Princess

1855-589: The mass basis to the weight basis. A propulsion system with a higher specific impulse uses the mass of the propellant more effectively in creating forward thrust and, in the case of a rocket, less propellant needed for a given delta-v , per the Tsiolkovsky rocket equation . In rockets, this means the engine is more effective at gaining altitude, distance, and velocity. This effectiveness is less important in jet engines that employ wings and use outside air for combustion and carry payloads that are much heavier than

1908-486: The night, in a similar fashion to railway carriages. First class passengers would have had their own bars, dining rooms and washrooms. A galley would have served all decks via freight elevator. The crew was to have consisted of 7 flight crews with their own rest quarters, and 40 cabin crew, as well as a steward as on a liner. The engines were installed away from the hull to avoid spray ingestion on takeoff and landing. They were to have been supplied with air through intakes in

1961-420: The opportunity have arisen. The company's directors were M D N Wyatt (chairman), Sir Archibald Philip Hope, 17th Baronet , Geoffrey Tyson, P D Irons and Capt H W C Alger (general manager). 75 per cent of the share capital were held by Saunders-Roe Ltd and the balance by Airwork Ltd. Following the completion of flying tests performed by the prototype, the British government exercised considerable indecision over

2014-400: The propellant. Specific impulse includes the contribution to impulse provided by external air that has been used for combustion and is exhausted with the spent propellant. Jet engines use outside air, and therefore have a much higher specific impulse than rocket engines. The specific impulse in terms of propellant mass spent has units of distance per time, which is an artificial velocity called

2067-440: The proposed giant flying boat. In May 1946, the bid made by Saunders-Roe was selected as the winner, leading to the company receiving an order for the production of three SR.45 flying boats. Work on the SR.45 commenced almost immediately upon receipt of the order. From an early stage in development, progress on the programme was subject to schedule overruns and higher than projected costs being incurred, leading to scepticism of

2120-445: The reliability of the engines and gearboxes continued to be problematic, but not to the extent that flight testing was prevented. Evaluation of the flying boat continued into 1953, during which particular attention was devoted towards addressing the difficulties uncovered. During the 1953 Farnborough Airshow, the prototype was displayed. Flight tests of the prototype continued up until 27 May 1954, by which point it had been found that

2173-563: The second and third would be suspended to await more powerful engines. On 22 August 1952, the prototype, G-ALUN , conducted its maiden flight , piloted by Geoffrey Tyson . The initial flight lasted for 35 minutes, in which the flying boat performed a complete circumnavigation of the Isle of Wight . According to aviation author Phillip Kaplan, the Princess had not been intended to fly that day at all and only taxiing tests had been scheduled to take place, and that Tyson had decided to proceed due to

Saunders-Roe Queen - Misplaced Pages Continue

2226-481: The time had no airport facilities at all. With the end of the Second World War, flying boats services were resumed with other types being operated, such as the Short Hythe , Short Sandringham , and Short Solent . However, the war had also produced a legacy of large runways and sizable airports formerly used for military purposes that could now meet the needs of a larger generation of land aircraft. Even prior to

2279-510: The use of Boeing 314s for the transatlantic route , many were requisitioned for service with the Royal Air Force (RAF) where they were typically used as maritime patrol aircraft . During the pre-war era, flying boats had been preferred for conducting long-distance flights as, unlike their land-based counterparts, they were not limited by available runway length – the majority of which were still grass-surfaced at this point – and as

2332-401: The viability of land-based aircraft, which did not have to compromise to accommodate the additional weight and drag of the boat hulls that were necessary on seaplanes, or the mitigating measures needed against the corrosion caused by seawater. Following the project's termination, the three airframes were stored with the intention of selling them on; however, upon receipt of a promising offer for

2385-616: The war's end, the British Air Ministry was enthusiastic on the prospects for reviving the shuttered flying boat routes. The Ministry approached two British flying boat manufacturers – Saunders-Roe (Saro) and Shorts – requesting that the two firms collaborate on the development and manufacture of a new aircraft, which would emerge as the Short Shetland . As such, Saunders-Roe designed the Shetland and manufactured

2438-416: The wing while Shorts produced the remainder of the aircraft. While two examples of the Shetland were completed, the project was considered a failure and the pair of flying boats were scrapped in 1951. Saunders-Roe considered the Shetland to have not resembled the flying boat that they sought to develop, but was otherwise a useful learning experience; even prior to the Shetland, the company had wanted to develop

2491-506: The working fluid and converts it to a hot, high-pressure gas which is expanded through one or more nozzles . Technically, most jet engines are gas turbines , working on the Brayton Cycle . Two types of jet engines, the turbojet and turbofan , employ axial-flow or centrifugal compressors to raise the pressure before combustion and turbines to drive the compression. Ramjets operate only at high flight speeds because they omit

2544-567: Was a British flying boat aircraft developed and built by Saunders-Roe at their Cowes facility on the Isle of Wight . It is the largest all-metal flying boat to have ever been constructed. The Princess had been developed to serve as a larger and more luxurious successor to the pre-war commercial flying boats, such as the Short Empire . It was intended to serve the transatlantic route, carrying up to 100 passengers between Southampton , United Kingdom and New York City , United States in spacious and comfortable conditions. To achieve this, it

2597-516: Was contacted by J. Dundas Meenan, consulting engineer from the firm Heenan, Winn & Steel, on behalf of the Peninsular & Oriental (P & O) shipping company. He was interested in a plane that could carry at least 1,000 passengers under the conditions of comfort of an ocean liner. Saro proposed project P.192, a 670-ton seaplane powered by 24 Rolls-Royce RB.80 Conway jet engines with 18,500 lb (8,400 kg) of thrust each. The aircraft

2650-471: Was decided early on to make use of newly developed turboprop technology, opting for the Bristol Proteus engine still in development to power the aircraft. The project suffered delays due to difficulties encountered in the development of the Proteus engine. On 22 August 1952, the first prototype Princess, G-ALUN , conducted its maiden flight . Between 1952 and 1954, the first prototype performed

2703-483: Was designed to have flown at a cruising speed of 450 mph (720 km/h) and an altitude between 30,000 and 39,000 ft (9,000 and 12,000 m). Its range would have been 2,100 mi (3,400 km). The route between London and Sydney had already been planned, via Cairo , Karachi , Calcutta , Singapore and Darwin (Australia). The fuselage would have had 5 decks with passengers divided into 6 person compartments with seats that could convert into berths for

SECTION 50

#1732786955037

2756-520: Was found. Over the ensuing years, several offers were issued with the intention of purchasing the Princesses, including two proposals which would have involved re-engining them with Rolls-Royce Tynes . In 1954, Aquila Airways had offered £1 million each for the stored Princesses, but this offer was rejected. In 1957, Saro itself had proposed the conversion of the aircraft to serve as landplane troop carriers/freighters. In 1958, information on

2809-455: Was to operate in BOAC's fleet to operate its transatlantic passenger services, Saunders-Roe decided to submit a bid based upon the earlier collaborative design specification. Following evaluations of a range of different propulsion methods and configurations, the design team selected the undeveloped Bristol Proteus – one of the first turboprop engines – to meet the enormous power requirements of

#36963