For educational purposes
From the Bell XV3 and XV15 to the Hawker and Harrier, a recounting of the planes that leap into the sky without a runway and some that were supposed to but didn't.
This episode tells the fascinating story of attempts to design airplanes that could be launched straight up into the air.
The history of aviation tells some unbelievable tales. None are more far-fetched than the ideas behind Vertical Take-Off.
Frustrated with the need for runway space and the often cramped conditions of war, aircraft designers got clever.
Using tilting wings and engines, jet nozzles and the aircraft itself, vertical take-off was a favorite theory.
In several cases, the planes did actually fly. The Osprey, with its tilting rotor, took flight in the 1980s.
As did the French tail-sitter, back in 1959.
Even more interesting are the plans that were made, but failed.
From the Bell XV3 and XV15 to the Hawker and Harrier, a recounting of the planes that leap into the sky without a runway and some that were supposed to but didn't.
This episode tells the fascinating story of attempts to design airplanes that could be launched straight up into the air.
The history of aviation tells some unbelievable tales. None are more far-fetched than the ideas behind Vertical Take-Off.
Frustrated with the need for runway space and the often cramped conditions of war, aircraft designers got clever.
Using tilting wings and engines, jet nozzles and the aircraft itself, vertical take-off was a favorite theory.
In several cases, the planes did actually fly. The Osprey, with its tilting rotor, took flight in the 1980s.
As did the French tail-sitter, back in 1959.
Even more interesting are the plans that were made, but failed.
Category
📚
LearningTranscript
00:00The End
01:50One thing that a helicopter cannot do that a conventional plane can is achieve a high speed.
01:56There is a pretty well absolute limit to how fast they can go because of the differences
02:00in speed at various points on their rotors.
02:03The tip may be travelling at near supersonic speed while the helicopter is doing only 200
02:07miles an hour.
02:09Even compound helicopters, with winglets and forward thrusting engines, suffer enormous
02:14drag penalties from the rotors and cannot be expected to easily approach the speeds attained
02:19by a modern fighter.
02:20But helicopters do what they do extremely well.
02:24And there are many applications, not only military, ideally suited to a helicopter.
02:28The biggest advantage they have can be put very simply.
02:32They can fly vertically.
02:34It is the justification for their existence.
02:37They can land on ordinary ships, in fields or forest clearings.
02:40They can take off from virtually anywhere.
02:43And if they can't land somewhere, they can hover just above it.
02:46If only they weren't so slow.
03:01Helicopters are only 50 years old.
03:03And yet they've developed so fast that their limits have not only been deduced, they've been
03:07reached.
03:16Modern combat aircraft have become increasingly addicted to concrete.
03:23Miles of it, straight and flat, with acres of parking bays and hard stands.
03:28And so have their support aircraft.
03:30All of this is expensive and requires massive permanent bases to support the concrete.
03:36These bases are scattered around the globe, serving every potential belligerent in the various
03:40alliances and hostile camps.
03:42Any theory of conventional modern warfare worth its salt is based around a preliminary battle
03:49for air superiority, either on a local or theatre level.
03:53And the easiest way to do this is to destroy the infrastructure needed to support an aerial
03:57force.
03:58In effect, the airfields are huge, immovable targets.
04:12Some countries have made their highways with straight stretches that are strengthened, to act as dispersal
04:18sites for their planes in emergency, foreseeing what would happen to their bases.
04:22The idea of a rocket-assisted take-off works better if your plane is actually capable of flight.
04:52And if your rocket is powerful and safe enough to use.
05:00A rocket-assisted take-off gives two major benefits.
05:04First, it allows fuel savings in getting a specified load into the air.
05:08And second, it shortens the take-off.
05:10These benefits have long been recognised, and powerful working systems of rocket and jet-assisted
05:16take-off, RATO and JATO, have been highly developed at times, though they have not always been
05:21particularly safe to be around.
05:24One enthusiastic user of such systems was the Second World War German Luftwaffe.
05:29They plugged their highly efficient, though cantankerous and dangerous, little rocket pods
05:34onto just about every plane they had at one time or another, with considerable success.
05:40Enormous quantities of fuel are normally consumed at take-off, and to be able to lessen that demand
05:45can considerably increase a plane's range.
05:47The second benefit, that of a shortened runway, has become more important subsequently, as
05:55planes have become less and less tolerant of rough ground conditions.
05:58It should be noted that German airfields became bomb crater collections on an almost permanent
06:03basis through much of the final phases of the war, and shortened take-off would have
06:08certainly been a virtue.
06:33The chemicals involved in these rocket engines were highly active, and required careful and
06:38hypothetical handling.
06:41The violence of the reactions to occur in firing the rocket, could all too easily be
06:45set off by accident, and the results of such accidents could be devastating.
06:51The protective clothing was worn with alacrity, in recognition of the danger.
06:56Flying boats gained considerably from the use of rocket-assisted take-off.
07:00Normally, a flying boat required a long run to unstick itself from the water, and the
07:04fuel tax of this was enormous.
07:07Then again, for a flying boat, it's impossible to actually damage the runway.
07:32The United States was another user of RATO, and extensive testing of various units was undertaken.
07:39Here, a Martin B-26 gets a rocket shove to reduce its runway use enormously.
07:51The interest in RATO grew considerably with the arrival of the jet engine.
07:55Jets had their special needs, and high on the list is the long concrete runway.
08:01Jet engines are susceptible to damage from ground debris, and also tend to have high take-off
08:06and landing speeds.
08:08Their advantages come into play in the air.
08:10On the ground, they demand mollycoddling.
08:13The world's air forces had to come to grips with the problem of the runway, despite their
08:17acute awareness of their vulnerability.
08:28Jet and jet assistance still were of more benefit in fuel savings than they were in shortening
08:33take-off length, and required their own additional backup, personnel and supplies, including some
08:38stores that were highly volatile.
08:41As systems, their inherent deficiencies and clumsiness made their overall use limited.
08:47Though a lot of effort went into the various attempts to make workable setups available, their
08:51widespread utilisation remained impractical.
09:00The most extreme scheme to use assisted take-off to do away with runways was the zero-length
09:05launch system.
09:07This can perhaps best be described as shooting aeroplanes off of the back of trucks.
09:12Tests of the idea were carried out with various aircraft, with surprising success, considering
09:16how ob the aim appears to be on the surface.
09:19The launch apparatus was developed by the Martin Company, with the obvious aim of increasing
09:24the dispersal of aircraft and lessening their attachment to established bases.
09:29The first launching was conducted on the 15th of December 1953, with an unserviceable,
09:34unmanned F-84 being shot off into the desert.
09:41The first piloted launch was made on the 5th of January 1954.
09:48Recorded acceleration loads were only 3.5 G's, marginally above a standard aircraft carrier
09:57catapult launch.
09:58The first piloted launch was made on the 5th of January 1954.
10:04Recorded acceleration loads were only 3.5 G's, marginally above a standard aircraft carrier
10:10catapult launch.
10:12When the few seconds of rocket burn were over, the plane had been brought up to a speed of
10:25175 miles per hour, well above the F-84's stall speed, and the pilots reported no difficulty
10:31in controlling the aircraft.
10:33Zero length launch worked, but it didn't really answer the need for aircraft that could take
10:40off vertically in a practical way.
10:43And though it was refined and applied to several aircraft types, it was in the end abandoned.
10:53What was needed was the ability for fixed wing aeroplanes to take off in the same way as rotary
10:58wing aircraft, straight up.
11:00And there has been constant research and development of various ideas to achieve that.
11:05Perhaps one of the more immediate solutions to present itself was to use an aircraft's
11:09propellers as rotary wings, on a horizontal plane, to get into the air, and then to swivel
11:14them to a vertical attitude for level flight.
11:18The Bell XV3 tiltrotor, completed in 1955, worked from this theory, and indeed its propellers
11:25were very reminiscent of a helicopter's rotors.
11:28It was to fly for 15 years, and provided a lot of valuable information.
11:35The Curtis Wright X-19 aircraft used propellers rather than rotors, although their shape was
11:58highly exaggerated with very broad cord and extravagant twist.
12:02These were driven by two engines, mounted side by side in the fuselage, through a complex
12:07series of gearboxes and shafts that could be run by one or both of the engines.
12:12Two planes were built, but only one flew.
12:15The program was cancelled before the second one could take to the air.
12:18The test series was short, disrupted by mechanical troubles, and rounded off with an in-flight
12:24failure on the test plane that saw it crash.
12:27In the period from its first tentative hover in November 1963 to the crash in August 1964,
12:33the plane left the ground only 50 times, for a total accumulated flying time of less than
12:38four hours.
12:41The X-19 had developed from an earlier Curtis Wright privately funded test aircraft, and
12:47the two demonstrated enough about the concept of tilt propellers to suggest that the system
12:51had its advantages, encouraging the company to further research and development, though to
12:56this date this has not led to any further aircraft.
13:03Doing away with the complex drive mechanisms, Bell's XV-15 tilted its engines, which were,
13:09to allow this, mounted on the tips of its wings.
13:12They drove large propellers that were a compromise between the requirements of helicopter rotor
13:17and aircraft propeller.
13:32The XV-15 made its first hovering flight on the 3rd of May 1977, and the two examples constructed
13:39have been highly successful, making hundreds of flights.
13:43The first actual transition from helicopter mode to level flight was made in July 1979,
13:49and the program has been so convincing that by 1983 the US Navy had ordered a development
13:54of the plane into production as the V-22 Osprey.
14:09With all the systems that require a plane to behave as a helicopter, and then change over to level flight,
14:14there are two very difficult areas to sort out.
14:17The first difficulty is to give sufficient control to the pilot during the helicopter flight mode,
14:22and the second is to safely go through the actual transition to behaving like a normal aeroplane.
14:28After that, as they say, it's a piece of cake, until the time comes to reverse the process and land.
14:34The idea of tilting various bits of the airframe to provide both take-off lift and then forward thrust
14:43has also been repeatedly applied to the entire wing, engines included.
14:48This allows a less artificial positioning of the engines than sticking them to the end of the wing,
14:53and can allow the wing control surfaces to be used to control the plane in hover.
14:57However, it means that the surface that is to provide in-flight lift has to be transitioned to level flight,
15:04and this presents a very difficult phase, where the propellers cease to act as rotary wings
15:09before the wing itself is actually working to keep the plane in the air.
15:12The Vertol Model 76, developed as a test craft for the Army and Navy, flew from 1957 to its retirement in 1965,
15:31and in that time made hundreds of successful flights.
15:34It was a very influential little plane, with much of the work done in sorting out its controls,
15:39and giving it reasonable stability, flowing on to inform later tilt-wing projects.
15:53Perhaps the most important of its successors was built for the Air Force by an LTV Hillier-Ryan consortium,
15:59based on Hillier's earlier X-18 craft, which had exhibited some vices in its career, particularly in hover control.
16:06The new plane was to be a much larger and more ambitious project,
16:10and was built to a 1961 Department of Defence specification to meet the needs of the services for a VTOL transport.
16:17It was given the number XC142, signifying very clearly that the intention was for the plane to go into full production.
16:32Five of the planes were built, four-engined, 58 foot long and with a 67 foot wingspan.
16:38Their proportions suggest that they are small planes, but they are quite big.
16:42They had a gross weight vertical take-off capability of 41,000 pounds,
16:47which made them quite a well-sized proposition for carrier resupply or battlefield aircraft.
16:53The propellers were not linked directly to the engines, but to a common cross-shaft.
16:58This guarded against asymmetric behaviour should one of the engines quit with the plane in hover,
17:03which would otherwise have led to certain disaster.
17:12There was a lot that worked about the XC142, but there was enough that didn't work to keep it from mass production.
17:19After the experience on the project, there was a lot of talk about getting back to the drawing board.
17:24Among its vices were transmission failures in the complex cross-linking,
17:28and that system's intolerance of wing flex.
17:31What may be small problems in level flight become major if they occur during hover,
17:37and in the period of testing of the XC142s, four of the five were badly damaged in accidents,
17:43while in hover position.
17:45The overwhelming problem with them was, however, that they vibrated badly
17:49and were almost insanely noisy.
17:52Up against the much bigger Hercules, carrying three times the load twice the distance,
17:57relatively quietly and with short take-off and landing to boot,
18:00the XC142 tiltwing, while still capable of being further developed, was abandoned.
18:18Aircraft with tilting ducts were another variation on the theme of swivelling parts of the aircraft,
18:23somewhat similar to the tilt props.
18:25The ducts had several additional virtues, in that they augmented the propeller thrust,
18:30and also worked as additional wing surface in level flight.
18:35Veins inside the duct could be used to give better control at delicate points during transition,
18:40and propeller turbulence was kept away from the wing.
18:44The Doak Model 16, completed in 1957,
18:47was among the most successful of early vertical take-off aircraft,
18:51and provided NASA, who conducted tests on it in conjunction with the Army,
18:55with much information.
18:57In particular, studies of the plane's power needs in hover and in transitional flight,
19:02made increasingly clear the enormity of the task ahead,
19:05in the pursuit of truly practical vertical take-off aeroplanes.
19:09The ducted fan system actually has a lot to recommend it.
19:38The Bell Corporation's two X-22As effectively proved the idea as workable,
19:43and very effective, in a long career.
19:45The X-22 first flew in March 1966.
19:49In August of that year, one was damaged beyond repair,
19:53but the other was to fly on till 1984,
19:56and was retired, still flyable, to museum life.
19:59The X-22's contribution to the science of flight was not limited to the ducted system,
20:06but it did show that the system works,
20:08and though there have to date not been any production aircraft using the configuration,
20:12the work of the X-22 still serves as a reminder of its potential.
20:29Another point about fans that had been established
20:32was that they considerably increased the effectiveness of jet engines
20:35in producing hover thrust,
20:37and this was the basis of the turbojet-powered Ryan XV-5A.
20:41The engine's thrust could be used either normally,
20:44to propel the plane in level flight,
20:46or diverted to the fans for hover mode.
20:49The two main lifting fans were embedded in the wing,
20:52with another stabilising fan in the nose.
20:55Once airborne, the fan's airflow was deflected by vanes to start the plane forward,
21:00and then the engine's thrust was diverted to the jet pipes,
21:03and the fan covers in the wing were closed,
21:05theoretically leaving a handy little fighter plane.
21:08The disadvantages included the domination of the available space in the plane,
21:22by all that ducting, fans and engine.
21:25However, there was a lot of promise to the use of fans with jets,
21:29and Ryan published proposals for a variety of applications,
21:32including high-speed interceptors, heavy transports and passenger airliners.
21:38All of these various avenues to vertical flight were being tested at the same time.
22:02The end of the Second World War had set off a period of reflection
22:06on the lessons for future warfare,
22:08and there had been several important factors indicating
22:11that vertical take-off aircraft were of the highest priority of need.
22:15The US Navy, not as beset by concrete as the Air Force, had its own problems.
22:20One of which was the experience of locking up large numbers of expensive warships,
22:25with escorting creeping convoys of merchant shipping.
22:28To release some of these warships for other duties,
22:31it would help if the merchantmen could carry more of their own defences.
22:35And from this came one of the earliest VTOL design competitions,
22:39with contracts going to two manufacturers, Convair and Lockheed,
22:43to build prototypes of midget VTOL fighters to operate from cargo ships.
22:48They were both to operate as tail-sitters.
22:52The Lockheed plane was given the designation XFV-1.
22:56Its configuration sprang from the active mind of Kelly Johnson, Lockheed's design wizard.
23:01The plane, called the Salmon, after a period of experimentation and development,
23:06refining the elements of its shape, came out looking superficially quite similar overall
23:10to a conventional small propeller driven aircraft.
23:14The biggest variation from the norm in its shape,
23:17was the 45 degree angling of the set of four tail fins that graced its rear.
23:27Construction of the Salmon proceeded fairly smoothly,
23:30and there was to be only four years between the order and the first flight,
23:34of what must be conceded to be a very radical proposal.
23:37In that time, an enormous number of problems had to be confronted and overcome.
23:42From the position of the pilot, to the use of casters on the fin tips as undercarriage,
23:47there were many aspects of the plane that were unique.
23:50While construction proceeded on some parts of the main assembly,
23:54development work continued alongside, refining other components
23:58and overcoming many problems that would ordinarily never concern an aircraft designer.
24:02The position of the pilot was one area that caused a lot of problems,
24:16and a satisfactory arrangement was never really sorted out.
24:19Other areas of the plane's special requirements, like maintaining fuel flow, were however resolved.
24:25Also overcome was the problem of undercarriage capable of settling the plane onto its tail in landing.
24:31Given the impossibility of setting what direction the tail would be moving,
24:35in hover at the instance of touchdown,
24:37or of guaranteeing truly vertical descent or a level landing platform on a boat at sea,
24:42the problem was complex.
24:44The solution looks deceptively simple, suggesting the wheels of a shopping trolley.
25:06A further complication around the pilot's position was the absolute necessity to be able to eject safely.
25:12There was obviously no way a normal ejection seat would do anything but shoot the pilot into the ground if used in a hover,
25:19and a special seat was designed to shoot the pilot up or forward, depending upon the plane's attitude.
25:25Because it didn't shoot him straight up, but at an angle,
25:28it also needed to throw him further to attain a useful height for a parachute to open.
25:33The system was, understandably, extensively honed over a series of tests.
25:42The XFV-1 was fitted with temporary fixed conventional landing
26:10gear for its first test flight series.
26:14It being wisely acknowledged as necessary that the plane proved that it actually flew controllably in normal operation,
26:20before proceeding with the more adventurous business of standing it on its tail.
26:25Even while undergoing its taxi tests, it showed a willingness to get airborne,
26:43and its first flight passed without problem.
26:45In level flight, the little plane proved to have no daunting vices,
26:50and the series proceeded to high-altitude test transitions.
26:54Here, problems were encountered, including one that was very serious and was not to be overcome.
27:00In transition from level to vertical flight,
27:03the plane's momentum saw it gain several hundred feet before it stabilised in hover.
27:08The pilot, with his back to the ground, was therefore left in a skittish and difficult to manoeuvre aircraft,
27:14trying to lower himself with little to no idea of what was below him, or how far away it was.
27:20Even screwing his neck round, he couldn't see much below him.
27:24This was obviously going to make landings significantly more difficult than was desirable,
27:29especially if one keeps in mind the deck of a freighter or a destroyer in mid-Atlantic.
27:46Despite the worrying experience of the pilots in hover,
27:49the tests went on to their next phase, to actually take off in the plane.
27:54Here, another insurmountable problem arose, with the plane's available power.
27:59There simply wasn't enough of it.
28:01In addition, there was inadequate control available to the pilot in hover.
28:05The combination of these factors, which made attempts at take-off nearly impossible,
28:10allied to the experience of the pilots in preparing for any vertical landings,
28:14experienced in the air, and a very unnerving prospect to look forward to,
28:18was enough to seal the fate of the project.
28:21It was written off as a learning experience, and the plane was retired.
28:25If one were desperate for a failure to attribute to Kelly Johnson,
28:29to offset his stream of resounding triumphs, then the XFV-1 might be it.
28:34However, as a test plane it answered a lot of questions,
28:37and it posed a set of new and very interesting problems
28:40for those working on vertical take-off aircraft.
28:47The other plane ordered in the 1950 decision, Convair's XF-Y-1 Pogo,
28:52proceeded in parallel and in competition with the Lockheed plane,
28:55and did not have that experience to draw on.
28:58However, it was a very different design,
29:01being a delta-winged plane with dorsal and ventral fins matching the wings.
29:05The multitude of control surfaces still struggled to get enough grip on the propeller's slipstream
29:10to give much stability to hovering flight.
29:13But in many other aspects, the plane worked quite well.
29:16The delta gave it more strength for less weight,
29:19and also gave it much better performance at low speeds and high angles of attack,
29:23obviously important in the transitions at take-off and before landing.
29:28Unlike the Lockheed plane, there was no way to configure the Pogo for level take-off,
29:47and so its first flight also included its first vertical take-off and landing.
30:02The experience the Lockheed pilots had already had was repeated in the Convair plane.
30:07Though it was far more capable of carrying out the transitions
30:10and actually taking off and landing,
30:12there was still no way for the pilot to see what was happening
30:15once he was in hover, staring at the sky.
30:18The coaching of ground crew by radio was of some assistance.
30:22But in all the tests of the tail-sitters,
30:24the situation of the pilot in landing was unsatisfactory.
30:28The powerful Allison engine would drag the plane up before settling into the hover,
30:32and the blind descent was a nightmare.
30:35Another notable vertical attitude plane was the Bell X-13.
30:48The preliminary work on the problems of the feasibility of reaction controls for jet aircraft
30:53had begun in 1947, backed by the US Navy,
30:56with the same objective that had created the Pogo and Salmon, self-defending convoys.
31:02When the Navy ran out of funds, the Air Force's attention was already rising in relation to its own needs,
31:07and the X-13 VertiJets were to fill an Air Force order.
31:11The secret of the X-13 was that it hung on a hook, and was designed to operate from a trailer.
31:29After a careful series of gradual steps ironing the problems out as they went,
31:33the team working on the project achieved what, on the face of it, seems an improbable aim.
31:38A portable plane, complete with aerodrome.
31:41The system worked quite well, but after the initial fanfare of astonished applause,
31:46when the plane first strutted its stuff,
31:48it seems to have immediately faded into an impenetrable obscurity.
31:52The two X-13s were among the most successful early jet VTOL aircraft,
32:07and the success and efficiency of their unlikely sounding mission
32:10was perhaps as advanced as anything in the vertical field before the Harrier.
32:14They proved that vertical flight on jet thrust alone was both technically feasible and practical,
32:20and left little to question about the flexibility and usefulness of such an arrangement.
32:25But they would have been a way left to go to get it operational.
32:28The pilots still could not see, and there were loading limitations.
32:45Even without the weight of the retractable undercarriage,
32:47the thrust of the available engines left little reserve of power.
32:51The X-13 idea could have been refined, but it's highly unlikely now that it ever will be.
32:58Using jets to obtain sufficient thrust to go straight up required a lot more power from the engine
33:13than was readily available until quite recently.
33:16And the seemingly obvious solution to this was to have two sets of motors,
33:20with one set only involved in getting into the air.
33:23Hence, the Rolls-Royce Flying Bedstead,
33:26which was involved in trying to sort out the tricky business of developing controls
33:30for a plane that's rising on a pillar of jet thrust.
33:33The system developed on such vehicles operates very much in the same way as the lunar lander.
33:39The principle of control is reaction jets.
33:41The principle of control is reaction jets.
34:04It was still true that the accident that happened in hover was generally going to leave no time for recovery.
34:10But the work done with aircraft like these broke down a lot of the barriers standing in the way of vertical flight,
34:16and made possible the use of far more conventional aeroplane shapes in VTOL Rolls.
34:21Though, of course, they themselves don't look like conventional aircraft at all.
34:25Where the Bell X-13 had quite practically hung itself up on a hook after a flight,
34:33there's been a lot of work on various systems for shortening the required landing length of aircraft,
34:38including another apparently fairly outrageous suggestion,
34:41to grab them with an arrestor hook and then slam them on their bellies on a rubber runway.
34:46Yet this too has been taken to the point where it actually works, and has been extensively tested.
34:52It was developed by the British, but the Martin Company showed a lot of interest in it
34:56as a companion system for their zero-length launch trucks,
34:59and the British showed the system off to several impressed American delegations.
35:03Despite the potential to miss the hook and sail back over the ship's side on occasion,
35:12the system worked after a fashion, and obviously cannot have been as silly as it sounds.
35:17Of course, crash barriers and arrestor wires have long been refined aboard carriers,
35:22and many planes have been fitted at one time or another to operate with these mechanical interventions.
35:27Apart from extreme examples like the rubber runway concept,
35:31the planes have clung to the weight penalty of their wheels,
35:34and most of the time such landings are routine and go through without incident,
35:39though it does remain hazardous.
35:41There is no fear of being tracked now.
35:42There is no fear of having quase same rate.
35:43There is no fear of having any Rollin,
35:44then it will rise and fall in the centre.
35:46There is no fear of having ongoing damage in the city.
35:47If nothing else, the rubber runway serves to remind us of the lengths to which experimentation
36:13was pushed in trying to bring the demands of aircraft for take-off and landing distance
36:18to heel.
36:20Vertical take-off experimentation saw another variation in the Bell Model 65 with its swivelling
36:25jet engine.
36:27It had a relatively short career and though it flew with the engine in both positions,
36:31it never did so on the same flight.
36:33No full transitions were made with the little plane.
36:36However, it settled several important basic issues and gave Bell the information it needed
36:41to proceed with its next, more ambitious design proposal.
36:45The Model 65 used engines off a missile and when they burnt out, after four and a half
36:50hours use, that was the end of the project.
36:55One thing the Model 65 does well is show off its control jets.
36:59The nozzles can clearly be seen in the end of the wing and the ducting along the side to
37:03take the compressed air to the rear cluster of nozzles is also evident.
37:07By constant and sometimes painful trial and error, the controls needed to hold a plane
37:12in relative obedience while hovering have been sorted out.
37:16The normal method of control with jet engine VTOL planes is the use of air pumped to the
37:21plane's extremities, being vented as needed to hold position.
37:26In early wind tunnel tests with large working models of the system, four pilots sat at controls
37:31operating different bits.
37:33It was extremely complicated.
37:34Now, though not less complicated, it's a lot more automated.
37:39The Bell Company has been absorbed in vertical flight research from the early 40s and has
37:44constructed an impressive range of prototypes exploring different approaches to the problems
37:48of getting a plane into the air without a huge runway.
37:52In 1956, they won a contract with the US Air Force to build a new plane, given the name
37:57X-14 to test their work on the concept of thrust vectoring and to serve as a test bed to sort
38:03out how to give pilots sensible controls for hovering flight, an area that was then still resolutely
38:08proving difficult.
38:11The X-14 was to be one of the most important aircraft in the long saga of vertical flight experimentation.
38:28In 1954 and 55, Bell had gone to the Air Force with a proposal for a VTOL lightweight day fighter,
38:35and had managed to get the Air Force very interested in the proposal.
38:40As a step in exploring the technology that would be needed for such a plane, the Air Force
38:44had authorised the company to build a technology test bed aircraft.
38:48Bell's primary concern was to test the use of vectored thrust, which seemed to offer the
38:53simplest solution to the use of jet engines, allowing a plane that sat in a horizontal attitude.
38:59The test plane was built as fast as possible and as cheaply as possible, which coincidentally
39:04led to it being as small as possible.
39:07It incorporated existing engines and scavenged its parts from all sorts of aircraft spares.
39:13It had no canopy and no ejector seat.
39:15It was the minimum needed to do the job.
39:22The scheme of vectored thrust is to blow the hot engine exhaust through moveable grills that
39:28aim them either at the ground or to the rear of the plane.
39:31On the face of it, a very simple approach.
39:33However, as is usual in these things, there are many complications.
39:38For example, if you point a powerful jet engine at something at close range, it is likely to
39:43do considerable damage.
39:45It will dig a pit in your lawn or it will make your concrete bubble and smoke alarmingly.
39:50As a result, one of the things that the engineers working on the X-14 project had to turn their
39:55attention to was the constitution of concrete and how to build a heat and blast resistant
40:00surface for the X-14 to test on.
40:13Here if you'll pardon the expression is the concrete embodiment of the X-Plane series.
40:18Aviation's history is the chronology of a cascade of ideas forming in the minds of individuals
40:23and being honed, expanded or debunked.
40:27The generations of knowledge have succeeded one another at a bewildering speed, drawing
40:31constantly on what is proven to imagine what might be provable.
40:36It's been only when a hypothesis is put to the test that its full meaning has been discovered,
40:41both in the significance, success and implication of the idea and also in the snags, complications,
40:46side effects, hazards and failure.
40:50On two levels, the X-Series enriched aviation by turning theory into hardware and then turning
40:56that hardware into practical machines.
41:00There are so many famous firsts associated with the X-Series, breaking the sound barriers,
41:05testing new materials, swing wings, high altitude flight.
41:08The X-14 itself was the first vectored thrust aircraft.
41:12In addition, there have been thousands of less famous firsts associated with technical advances,
41:18control systems and avionics.
41:20Much of what is known about flight today, and affects the planes of today and will affect
41:24those of tomorrow, rests on the results obtained by planes in the X-Series.
41:30It even seems likely that the X-14 may have been the first aircraft to have a pink circle
41:35for landing and take off.
41:39The X-14's flight test program started on the 17th of February, 1957, and it completed
41:58the evaluation series for Bell in 1959.
42:02The Air Force then taking the plane over for an extended series of further general VTOL testing
42:07and pilot familiarisation.
42:10Extended seems an inadequate word, actually, as the plane was to continue to be used by the
42:14Air Force and NASA until the 29th of May, 1981.
42:19It was that day damaged in an accident and was written off as no longer airworthy.
42:24Today, fittingly for such a productive and successful little pioneer, it's preserved in a museum.
42:32Work on various schemes continued all over the world.
42:41In Germany, the Dornier 31 was a combination of lift jet and vectored thrust configurations.
42:49The Lockheed Company invested a lot of its energy in augmented jet lift, in yet another
42:53method of heaving a plane straight up.
42:56Here, the theory stated that introducing jet thrust into a chamber of air would create
43:01additional lift from the engine's power by the rush of air into the chamber.
43:05And this was undoubtedly true, as it had been repeatedly shown to occur in test installations.
43:11However, in working the system into an aeroplane, the weight penalties of the installation went
43:16a long way to cancelling out the augmented thrust of the power plant.
43:19And Lockheed's Hummingbird was not a raging success, being later rebuilt with dedicated lift engines
43:26to test a completely different configuration.
43:28The use of lift only jets by Lockheed and Dornier followed what seemed to be the emerging dominant
43:57pattern, using a number of small jets which only worked when the plane was in hover.
44:02The main engines were much larger power plants which operated in all phases of flight.
44:07The weight penalties of this are obvious, but they would be partially compensated for.
44:12A plane that had only its main power plant to obtain lift would need an extravagantly big
44:17engine which would, in normal flight, never be called upon to deliver much of its available
44:21power.
44:22Of course, what happened to change the status quo was a breakthrough engine developed by
44:28the Bristol Company in England, the Pegasus.
44:32Around this engine, the Hawker Company were able to develop their P1127, forerunner of the
44:37Kestrel and then the Harrier.
44:40The P1127 was a major step forward, an emphatic proof of the thrust vectoring approach, and
44:46drew extensively on the data obtained in the X14 program.
44:50It was designed around the new engine, but for once, this did not place too unreasonable
44:55a set of demands upon the plane's shape or capability.
45:03The creation of a new engine is an expensive business, and to create a new engine for one
45:08application places a huge research and development load onto only one customer.
45:14And in the case of the P1127 and its basic development into the Kestrel, a lot of cost went
45:19into producing only a handful of aeroplanes.
45:33When the Kestrel project was completed, a lot of time and effort was put into design of
45:37a supersonic version, the P1154.
45:41This almost caused the abandonment of the whole area of research by the company, due
45:45to the huge bills involved and the lack of UK government support.
45:50Eventually, the plane that did emerge from Hawkers was a subsonic fighter.
45:55And initially, there was little to no enthusiasm from the fighter pilots, who preferred to be
45:59at the controls of something that went considerably faster, preferably with as much glamour as possible.
46:06Today, the Harrier has come a long way, and the new AV-8B model incorporates a large number
46:11of advances and improvements.
46:14Though still subsonic, it now has doubled load capacity and range.
46:19The Harrier's successful use in combat and the successful development of tactics for its
46:23pilots have combined to underline that it is one of today's most potent and dangerous
46:28fighting machines, and it has been adopted for various uses.
46:33The McDonnell Douglas company has been involved in the project, together with British Aerospace.
46:38And the two companies have cooperatively developed the Harrier's capability and refined its airframe
46:43to ensure that it remains the most capable vertical take-off plane in the world, at least for
46:48the moment.
46:49Who knows what'll be next, or what method it'll use.
47:09Next in strange planes, why do planes look like they do?
47:13How did they get that way?
47:15Don't miss Strange Shapes.
47:20How did they get that way?
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