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Nebakenezzer posted:It looks amazing. Filmmaker of Miyazaki's caliber + Miyazaki's love of machines + story of the man who designed the Zero = sold. Not so much; RJ Mitchell was sick with cancer for a number of years before the Spitfire flew. Whether or not his work on the project interfered with getting proper treatment is debatable, but it does make for a rather  story of sacrifice for Queen and Country regardless of its veracity.
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Jan 15, 2014 02:36
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Neat stuff Lushka; you're giving us a very rare perspective into Soviet aviation with this. If you don't mind, I have a few questions of my own: -Did your grandfather ever participate in any inflight refuelling while flying the Tu-16? For those that don't know, certain variants of the Tu-16 used an unusual wingtip-to-wingtip refuelling system, where the receiver would collect the drogue from the tanker by flying over top of the line, then move laterally until it connected; to my eye, it was a silly and dangerous solution. Here's a pic:  -Was he able to participate in normal VVS operations even with his restriction on where he could go? Was his aircraft ever intercepted by Western fighters? If so, could he describe what it was like from a Soviet perspective. -Considering the length of his career, your grandfather likely saw quite a few aircraft types come and go in both civilian and military service. Would he be willing to relate what the general consensus was amongst the aviation comminity on some of these, namely the M-4/3M, the Tu-22 and the Tu-144? Are there any aircraft that I haven't mentioned that the community had strong opinions for or against? -What was Aeroflot's opinion of the IL-62 in general? Based on what I've read and what I've heard, it was lukewarm at best once the whole "shiny new jet" mentality wore off. -Of all the aircraft he worked with, which does he look upon most/least fondly and why? MrChips fucked around with this message at 04:41 on Jan 15, 2014 |
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Jan 15, 2014 04:39
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BobHoward posted:One approach to wires that I've heard of is a form of lidar. Uses rotating mirrors to scan a laser rangefinder beam and image the environment close to the aircraft, plus some post processing to pick out likely lines, provide collision warnings, and so forth. If you design the receiver correctly this can be a much more effective machine vision system for reliably detecting thin wires in poor ambient lighting than any pixel array imaging system. There is a system out there that combines a VLF radio receiver tuned to pick up the 50/60 Hz radio frequency emissions from power lines; I've never used it flying fixed wing, but supposedly it clicks like a Geiger counter based on how close the aircraft gets to a power line. Doesn't do any good if the line isn't energised, though.
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Jan 16, 2014 06:58
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Ola posted:Oh! The aeroplane! 
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Jan 17, 2014 00:29
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hobbesmaster posted:Comparing against the U2's turbojet is cheating. I can't imagine what a 1950s SAC base must have been like. Correct me if I'm wrong but I think the U-2 fleet has been re-engined with GE F118 turbofans (the non-afterburning variant of the F110 used in the B-2). Doesn't mean it'll be any less quiet than a J57 or J75-powered U-2 though. Also, between the window-rattling drone of a B-36, the rocket-assisted B-47 or the smoke-belching, water-injected, so-loud-they'd-literally-shake-themselves-to-pieces early B-52s and KC-135s, a 1950s SAC base would have been one hell of a smoky, noisy place.
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Jan 18, 2014 17:50
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Tsuru posted:Haven't seen this one posted yet: That's pretty awesome; I've always wondered what the inside of those aircraft looked like - the most I have seen up until now was a not-very-representative evacuation schematic. Also, I binned the Centurions, Part Two info post scheduled for tonight. In it's place will be something rather more interesting!
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Jan 21, 2014 03:07
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At the conclusion of World War II, military planners and aircraft designers were left with some very hard lessons about the nature of air combat. Aircraft weight and performance had increased dramatically over the course of the war, and with that came the need for much larger and heavier runways; gone were the days when you could operate a squadron of Spitfires off a large grass field and consider that adequate air defense. The problem with these new and enormous airfields was that in the event of a war, you can guarantee they would be the very first targets of an enemy attack plan; there is no better or safer way to destroy an air force than to blow it up while it’s still on the ground. Fortunately, the recent development of the gas turbine engine offered a potential solution; the compact size and light weight of a gas turbine, combined with its incredible power output, might, and I mean just might, allow a new aircraft to forego the need for a runway entirely, but nobody knew what such an aircraft should look like, or what kind of engine to use. So many possibilities...so many potential failures... The Triumph of Thrust Over Gravity (and Sense) – A Brief Account of the (Unfortunate) History of Vertical Takeoff Aircraft Part One – The First (Mis)Steps The idea of an aircraft that could take off on a very short runway, or in fact with no runway at all, has always been an appealing idea from a military planner’s perspective. As mentioned before, it eliminates (or at least greatly reduces) the need for large, centralised airfields, where aircraft and their support infrastructure are vulnerable to all manners of attack. At sea, an aircraft that doesn’t need a runway would allow nearly any ship to carry a very powerful and versatile air asset without relying on large, costly and equally vulnerable aircraft carriers for air support. Every military service in nearly every developed nation saw the value of such an aircraft, and very nearly all of them began development of vertical takeoff and landing (VTOL) aircraft; specifically, VTOL fighter and attack aircraft.  Focke-Wulf Triebfluegel gyrodyne interceptor; one of the most insane aircraft concepts of all-time. What’s more insane is that it is a largely sound idea. Discounting the dabbling of the Germans in the closing days of World War II with VTOL aircraft, the Americans, specifically the US Navy, were the early leaders in the development of VTOL aircraft. In 1950, the Navy issued a contract to build and fly a pair of prototype VTOL fighters, capable of taking off and landing on the deck of virtually any ship in the Navy. Lockheed and Convair both responded with designs and in 1951, the Navy selected Lockheed as the winner of the contract. Now what is remarkable about both of these designs is that they are both “tail-sitters” – a subspecies of VTOL aircraft that are entirely conventional aircraft in nearly every way save for one; they truly land and take off vertically. The advantage of tail-sitting is that the aircraft is, as I mentioned, not a whole lot different in terms of construction to any other aircraft. The disadvantage of tail-sitting is, well...pretty much everything else. By 1953, Lockheed had finally finished their aircraft, a rather ungainly (but unmistakably Lockheed) design, called the XFV-1 “Salmon”. The XFV-1 used a single 5,300 horsepower Allison YT-40 turboprop engine (which was actually two Allison T38s connected to a common gearbox; not a layout conducive to good reliability) driving a pair of contra-rotating propellers in the nose of the XFV-1. Other than the location of the landing gear and the configuration of the tail surfaces, the XFV-1 was for all intents and purposes a very conventional aircraft.   Lockheed XFV-1 “Salmon”. The small size and light weight of the XFV-1 combined with the relatively high propulsive efficiency of the turboprop engine to allow it to take off and land vertically...at least, in theory. The reality is that the YT-40 engine simply didn’t have enough power for the XFV-1 to achieve vertical takeoff or landing, and the more powerful definitive T40 that would have permitted vertical flight never materialised. As a result, the XFV-1 was fitted with a very long set of conventional landing gear and flown like a conventional aircraft.  Lockheed XFV-1 in testing (and on landing gear that allowed conventional takeoff and landing). The XFV-1 first flew officially in June of 1954 (it did briefly lift off on a high-speed taxi run in December, 1953, but those don’t count) and flew for a total of thirty-two times, in which numerous problems with handling characteristics cropped up. The aircraft transitioned to a hover once at altitude, which merely served to demonstrate that the XFV-1’s poor handling characteristic got progressively worse as its airspeed dropped, but it never achieved its goal of vertical takeoff and landing. Not long after its first flight, the XFV-1 program was cancelled by the Navy. While the poor handling of the XFV-1 certainly didn’t inspire any confidence in it, the single biggest reason why it was cancelled was that the XFV-1 was hopelessly obsolete when it finally flew; it was at least a full generation behind in terms of performance. All the while that Lockheed struggled with the XFV-1, Convair stubbornly persevered with their own design, the XFY-1. In many ways, the XFY-1 was very similar to the Lockheed XFV-1 in that it shared the same powerplant and had broadly similar performance, but Convair opted for delta-shaped wings and tail surfaces, much like their conventional fighter designs of the era.   Convair XFY-1; the loser of the US Navy’s VTOL prototype competition of 1950, and ironically the only one of the two that actually took off and landed vertically. Proceeding on company money only meant that the XFY-1 program went at a much slower pace than the Lockheed XFV-1, but Convair went one step further than Lockheed and decided to test the aircraft through its full mission parameters from day one...no conventional take offs and landings allowed. To test the hover characteristics of the XFY-1, Convair built an enormous tether system in an old airship hangar (later moved outside) to familiarise themselves with the XFY-1.  Convair XFY-1 in its enormous outdoor tether rig. The XFY-1 first flew on the tether in April of 1954 (two months before the XFV-1) and accumulated almost sixty hours of tethered flight, where it earned the nickname “Pogo” (as it did nothing but hop up and down all day long). Eventually Convair released the XFY-1 from the tether and allowed the aircraft to fly freely, performing true vertical takeoffs and landings, as well as the complicated and risky transition to and from horizontal flight, but they too encountered serious handling issues with the aircraft, as well as considerable difficulty landing too – the pilot had to look over their shoulder to see the ground, which was hard enough on flat land, never mind on the pitching, rolling deck of a US Navy cruiser. With the cancellation of the Lockheed XFV-1 program, Convair was pretty much forced to throw in the towel on the XFY-1 and cancelled further development on their aircraft as well. Not to be outdone by the Navy, the US Air Force issued an experimental contract to Ryan Aeronautical for an experimental jet-powered tail-sitter. Ryan had been researching VTOL aircraft since the end of WWII, when they first proposed that their combined piston/jet powered FR-1 Fireball fighter be adapted as a VTOL aircraft. Nothing came of their proposal ultimately, largely because the FR-1 was found to be deficient structurally in 1947, with the entire fleet being removed from service not even a year into service.  Ryan FR-1 Fireball fighter. Business up front, party at the back, structural failures in between. Undeterred by their failure with the FR-1, Ryan continued to study VTOL jet fighters, including one proposal for the Navy for a submarine-launched fighter aircraft, the F3R. As they were the leaders in this field, it was only natural for the US Air Force to contract Ryan to build them a proof-of-concept VTOL fighter. Ryan responded with the X-13 Vertijet, a small (about the same size as a Cessna 172!), delta-wing aircraft fitted with a single Rolls-Royce Avon turbojet engine.   Ryan X-13 Vertijet; about as close to an egg-plane as you can get. Aircraft at top has temporary conventional landing gear to test its flight characteristics without the need for difficult vertical takeoff or landing. Through an innovative system engine bleed-air powered “puffer” jets and a thrust-vectoring exhaust nozzle, was able to maintain control even with zero airspeed; unlike the XFV-1 and XFY-1, the X-13 did not benefit from the considerable air stream generated from the propellers of those aircraft, which allowed them to use their conventional control surfaces for control in the hover. The X-13 flew conventionally for the first time in December of 1955, then vertically for the first time in May of 1956. The X-13 enjoyed rather more success than either the XFV-1 or the XFY-1 and like the XFY-1 it too performed the transition from vertical to horizontal flight (and back), but that is admittedly a rather low bar to reach. While the X-13 did in fact demonstrate that a pure-jet tail-sitter was possible, it was such a small aircraft that it really didn’t prove that any such aircraft could actually be useful; the X-13 was basically large enough to accommodate the pilot and the engine and very little else.  Ryan X-13 attempting to recover to its specially-built recovery trailer. Attempting being the key word; it was an extremely difficult and risky maneuver. Notice that the pilot’s seat has tilted forward for better visibility for takeoff and landing. Like the other tail-sitters, the X-13 proved to be very difficult to land on the specially-built recovery trailer, which the aircraft was supposed to snag with a hook underneath the fuselage while hovering. Ultimately, the X-13 program was ended in September of 1957, citing recovery difficulties, lack of utility from its design and the general lack of a requirement for an aircraft of that nature. Playing with Fire (and Rubber) The X-13 program also largely coincided with the development of a new train of thought within the US Air Force; since VTOL aircraft are obviously compromised from an operational standpoint, maybe instead of insisting the aircraft take off and land vertically we could try them taking off with no runway? Rather quickly, the idea was hatched to fit a conventional fighter aircraft with a large solid-fuel rocket engine and fire it off a trailer, with the aircraft later recovering at a conventional airfield. Thus, the concept of “zero-length launch” or “ZELL” was invented. In 1955, a Republic F-84 Thunderjet was fitted for the first trial of the ZELL concept. Flying unmanned (mercifully), the launch was a success, with the F-84 achieving a safe speed and altitude boosted by the rocket alone.  Republic F-84 Thunderjet performing zero-length launch. Surprisingly, not as dramatic as it looks. Manned trials began soon after, and later the larger and faster North American F-100 Super Sabre was tested in a ZELL configuration, as well as a Lockheed F-104 Starfighter by the Luffwaffe in Germany. The Soviets too experimented with ZELL, launching a number of Mikoyan MiG-19s in the mid- to late-1950s. Again, these trials were successful, with one successfully launching an F-100 from inside a hardened shelter!   North American F-100 Super Sabre (top) performing a zero-length launch and a Mikoyan MiG-19 sitting on its launch rail (below). However, there were still issues, chief among them the recovery of the aircraft. While it is all very well and fine to launch an aircraft without a runway, landing still required large conventional runways. This begged the question; “why even bother with ZELL then?”...that is, until someone came up with one of the most ill-conceived ideas in aviation history; the “Zero-Length Launch, Mat-Assisted Landing” concept, or ZELMAL for short. With the ZELMAL concept, the aircraft would be launched from back of a trailer as in the ZELL experiments, but instead of returning to a conventional airfield, the aircraft would fly to a recovery area, where a large, inflatable rubber mat would be deployed. The aircraft would fly along and snag a cable in mid-flight with a carrier-style arresting hook, then belly-flop down onto the mat; essentially a barely-controlled crash landing.  Republic F-84 Thunderjet performing a mat-assisted landing. ZELMAL throws the whole “if you can use the aircraft again it’s a good landing” phrase into doubt. Three mat landings were performed, with only one of them being anywhere near good enough to be called a success; the first landing ripped the mat apart and wrote off the F-84 performing the test, badly injuring the test pilot in the process. The second was largely successful and on the third test, the arresting hook tore a long gash in the only remaining mat, destroying it in the process. The ZELMAL concept was quickly killed off, with further efforts concentrating on ZELL only. Ultimately, by 1959, the entire concept of ZELL was killed off for good, as it not only did precisely nothing to reduce the need for airfields, but there were huge and intractable security issues concerning nuclear-armed aircraft being parked all over the countryside. Not the Only Ones Playing With Fire So far, we’ve shed some light on the American efforts at VTOL aircraft; now, let’s look at what was happening on the other side of the Atlantic. The 1950s were a golden period of innovation in both the French and British aircraft industries, with new prototypes and concept aircraft appearing almost weekly from the likes of Shorts, Bristol, Fairey and the various quasi-national French aircraft companies. Like the Americans, the idea of a VTOL aircraft was certainly a very appealing one, if only from the perspective of boosting their war-ravaged economies. Interestingly in Europe, initially the engine manufacturers themselves took the lead, with Rolls-Royce in the UK and SNECMA in France both building “aircraft”...if you could call them that. Rolls-Royce was first out of the blocks, building what appeared to be a jet-powered scaffold, the so-called “Thrust Measuring Rig”, better known as the “Flying Bedstead”.  Rolls-Royce Thrust Measuring Rig at the Farnborough Air Show. The “roll cage” around the pilot, designed to protect him in the event of an accident, was ironically what killed its pilot. Built under comically tight security (hence the non-descript name of Thrust Measuring Rig), Rolls-Royce took two of their successful Nene centrifugal flow turbojets, Rolls-Royce mounted them back-to-back (to cancel out any gyroscopic effect from the engines) and exhausted them downwards through a pair of vectoring nozzles. Attitude control was provided by a series of “puffer” jets driven from engine bleed air, fed through a complicated automatic stabilisation system. Flying for the first time in 1953, the Flying Bedstead was in fact the first jet-lift VTOL aircraft ever to fly, beating the X-13 to the skies by a full two years. More importantly, the Flying Bedstead pioneered the concept of vectoring the engine thrust downwards, thereby keeping the aircraft level to the horizon; a concept that would prove most useful in the coming years.  Rolls-Royce Thrust Measuring Rig out for a test flight. The Flying Bedstead was not without its problems, however. Apart from its lack of such important things as wings, it was extremely difficult to fly, partly because of its total instability in all three axes, but mostly because the slow throttle response of the engines made height control almost impossible. Added to that, it had no yaw control whatsoever, and had a nasty tendency to weathervane in the wind; combined with an alarming pitch attitude needed to counteract the wind, the Royal Aircraft Establishment (RAE, responsible for all experimental aircraft testing at the time) decided that it would never fly in winds of more than 12 miles per hour. In spite of all these issues (and a fatal crash involving the second aircraft), the program was nonetheless deemed to be a success. Meanwhile in France, SNECMA initially took a different (and much simpler) approach to VTOL. Instead of building a tail-sitter like the Americans or a complex rig like Rolls-Royce, they simply took one of their highly successful Atar turbojets, stood it on end and called it a day.  SNECMA C.400 P-1 Atar Volant undergoing a tethered test flight. Probably the simplest VTOL aircraft ever built. This aircraft, called the C.400 P-1 Atar Volant (“Flying Atar”), initially flew under remote control in 1955, initially tethered to test the aircraft’s stabilisation and control system. After P-1 completed nearly 250 flights, the French Air Ministry and SNECMA were satisfied with the handling of the aircraft and ordered two follow-up aircraft; the C.400 P-2, a manned version of the P-1 and the C.400 P-3, a P-2 with an enclosed cockpit that made it more closely resemble a proper manned aircraft.  SNECMA C.400 P-2 Atar Volant. The P-2 flew for the first time in May of 1957 and two months later, absolutely stole the show at the 1957 Paris Air Show. Taking off vertically, the P-2 hovered slowly down the runway at Le Bourget, rolling and pitching the whole time. At show centre, the aircraft stopped, climbed to 500 feet then returned to land directly in front of the crowd, to the adulation of all. After its show-stopping performance, the P-2 underwent a further 123 test flights, reaching altitudes as high as 1,500 feet in the process.  SNECMA C.400 P-3 Atar Volant undergoing reverse airflow testing on a train. Following up to the P-2 was the C.400 P-3; though it was built full-scale, the P-3 was never used for anything beyond ground testing, including a series of tests where it was strapped backwards to a high-speed train to test the engine’s response to airflow opposite the direction of its thrust. One of the biggest reasons why the P-3 never flew is that the French Air Ministry took the fateful step of deeming the P-2 program to be a sufficient basis for a fully-functional VTOL aircraft, which they directed SNECMA to design post-haste. Working with Helmut von Zborowski, a German engineer who came to SNECMA via Dornier and BMW after the war, SNECMA designed an aircraft that was essentially a C.400 P-3 wrapped with an annular wing for lift in horizontal flight. Like the C.400, this new aircraft was to be a tail-sitter...this is the part where we start shouting “THAT’S NOT A GOOD IDEA, DON’T DO IT!” to the screen, because it just isn’t. The end result was the SNECMA C.450 Coleoptere (Beetle):   SNECMA C.450 Coleoptere (above and below). The Coleoptere was a very compact aircraft, measuring just twenty-six feet tall and ten and a half feet across the wing, necessitated by the need for light weight; it weighed just 6,600 pounds. Combined with a new version of the Atar putting out 8,100 pounds of thrust, the Coleoptere was not only (theoretically) capable of vertical takeoffs and landings, but with any luck it should have been able to nudge 500 miles per hour in level flight. Like the British experience with the Flying Bedstead, SNECMA decided that the Coleoptere needed a complicated system of “puffer” jets combined with a complicated gyro-based automatic stabilisation system. In addition, the ejection seat of the Coleoptere would tilt forward 20 degrees in vertical mode (much like the Ryan X-13) to help provide the pilot with a better view of the landing area.   [super]SNECMA C.450 Coleoptere on its transporter/erector trailer (above) and actually flying (below). The trailer is just for transport, as the aircraft has its own landing gear. Tethered flights of the Coleoptere began in April of 1959, with the first free flight coming at the beginning of May of that year. Three more free flights were made over the next two months and by the end of June, SNECMA felt it was time to attempt the translation from vertical to horizontal flight – the riskiest part of any VTOL aircraft’s flight. On the 25th of July, 1959, the Coleoptere took off and climbed to 300 feet and attempted to transition to horizontal flight (vertical to horizontal being the easier of the two transitions). Unfortunately, the aircraft departed controlled flight and crashed; the test pilot ejected and survived, but sustained injuries serious enough to end his flying career. With the crash of the Coleoptere, the French dream of a single-engine VTOL ended with it; SNECMA never built another aircraft again, either. Coming Next Week: The Triumph of Thrust Over Gravity (and Sense) Part Two: More Engines, Many More Problems
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Jan 21, 2014 07:08
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MAIN POSTS Myasishchev M-4 "Bison" Myasishchev M-50 "Bounder" Sukhoi T-4/Myasishchev M-18/Tupolev Tu-160 "Blackjack" Sukhoi Su-9/Su-15 "Fishpot"/"Flagon" Tupolev Tu-22 "Blinder/Tu-22M "Backfire" Tupolev Tu-128 "Fiddler" Mikoyan-Gurevich MiG-25 "Foxbat"/MiG-31 "Foxhound" Sukhoi Su-27 "Flanker" family Tupolev Tu-95 "Bear" Republic XF-103 and North American XF-108 SHORT POSTS McDonnell-Douglas/General Dynamics F-4X/RF-4X Tsybin RSR Lockheed D-21 HISTORY OF...POSTS VTOL Aircraft, Part One
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Jan 21, 2014 07:09
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^^^You bet they do.FullMetalJacket posted:If only your opinion was valid. Lifting bodies/blended wing designs offer big advantages over the conventional tube and stick. The lift coefficient and efficiency gains alone are enough reason to produce them instead of just being parasite/surface drag/dirty air factories. On the other hand, wing-mounted engines provide nice clean airflow into the engine, plus their weight helps reduce bending and torsion moments on the wing structure, allowing for a comparatively lighter structure. Minor benefits include ease of access for maintenance and less need for deicing. E: The only reason why most business jets still have rear-mounted engines is for reduced cabin noise (which is an important concern in those aircraft). Though if you ask a 20-Series Lear pilot they might disagree (if they could hear you that is), what with its oddly megaphone-shaped fuselage. MrChips fucked around with this message at 03:51 on Jan 24, 2014 |
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Jan 24, 2014 03:47
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FrozenVent posted:No chance the brits would happen to have a bunch of obsolete last generation fighter jets sitting around, never been used, that we could buy for five times the price? Cause that worked out great for the navy. Actually they do! They have a whole pile of (largely useless) limited-capability Tranche 1 Eurofighter Typhoons that'll be retired early as the RAF doesn't have the money to upgrade to them the fully-capable Tranche 3A. Considering our history of military procurement, they sound pretty much perfect for Canada! 
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Jan 24, 2014 22:18
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Captain Postal posted:I seriously can't think of an instance of FADEC failing ever, let alone failing without the pilot being aware of a problem (except the Qantas A388 which had its entire front spar destroyed cutting the control links to the engines so it was pretty loving obvious there was something wrong). I can, and of course it involves the biggest joke aircraft this side of the F-35 - the Eclipse 500! quote:An Eclipse EA500 airplane, N612KB, sustained no damage when its flight crew encountered a loss of thrust control with both engines at maximum power thrust during an approach to land on runway 22L at the Chicago Midway International Airport (MDW). A go-around was performed and the crew shut down the right engine on base leg. The left engine went to flight idle and the crew encountered a total loss of thrust and continued loss of thrust control. The crew declared an emergency and performed a forced landing on runway 22R. The two airline transport rated pilots and two passengers were uninjured. Not so much a FADEC failure but a software glitch causing the FADECs to flip the gently caress out.
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Jan 27, 2014 00:27
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Tony Montana posted:I love it, but it's got to be the UK version and not the US. Can't handle the US announcer and that 'repeat the same thing over and over every 30 seconds' that US shows do a lot of. They way over sensationalize as well. Just because a show is good doesn't automatically make British...Mayday is actually a Canadian-made TV show.
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Jan 27, 2014 22:40
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The Triumph of Thrust Over Gravity (and Sense) – A Brief Acccount of the History of VTOL Aircraft Part Two - More Engines, Many More Problems After the rather unfortunate history of tail-sitter vertical takeoff and landing (VTOL) aircraft, it shouldn’t be much of a surprise that a number of aircraft manufacturers came to their senses and deemed VTOL as a pipe dream at worst or at least something that was better left to helicopters and their ilk. However, new technologies that came about in the mid-to-late 1950s completely changed everyone’s minds; suddenly, VTOL aircraft – possibly even a supersonic aircraft – were back on the table, and in a big way. So, what happened? A major evolution in jet engines and a revolution in the very concept of VTOL aircraft design. One of the biggest problems with a VTOL aircraft, especially one powered purely by jet engines, was the issue of fine height control. Jet engines respond slowly even today, but back in the early 1950s, even a minor power change requested by the aircrew would need a couple of seconds before the engine would respond – not ideal when you are trying to land safely in changeable, real-world weather conditions. The concept of using the aircraft’s main engine for hover power only served to exacerbate the problem further; simple physics will tell you that a large engine will respond to power commands much more slowly than a small engine. On top of that, there is the difficulty of redirecting the thrust from the main engine downwards – the equipment needed perform that feat would be far too heavy and too complex in an aircraft family that already had far too much of both. All of these things made it difficult to conceive of a practical, flat-landing VTOL aircraft, until Rolls-Royce came up with a novel solution; a small, lightweight but very powerful turbojet engine that could be mounted vertically in an aircraft to provide vertical lift...the so-called “lift-jet” engine. At the same time, a couple of aircraft manufacturers decided that instead of vectoring the aircraft (as in a tail-sitter) or vectoring the thrust from the engines (which was a pipe dream), why not vector the engines on the airframe? Lift by Jet Engine(s) Having witnessed the difficulties encountered both by the American tail-sitters and their own Thrust Measuring Rig, Rolls-Royce set about designing a jet engine designed solely to provide vertical lift. Their concept was that a compact, lightweight and extremely powerful engine could be mounted vertically inside an aircraft, either by itself or in batteries of several engines, to provide vertical lift. In 1955 their first of the so-called “lift-jet” engines, the RB.108, ran for the first time. The RB.108s specifications were very impressive; it produced almost 2,400 pounds of thrust out of a package no larger than a garbage can while weighing no more than 270 pounds – performance that would stand up well even sixty years later.  Rolls-Royce RB.108 lift-jet engine. One of the very first jet engines built for vertical lift use. At the same time that Rolls-Royce was developing the RB.108, the British Ministry of Supply tasked Short Brothers of Belfast (the oldest independent aircraft company in the world at the time, also known as Shorts) to build an aircraft to validate the concept of separate lift and cruise engines. Shorts designed a very compact aircraft (like many VTOL prototypes) designated the SC.1, with four RB.108s mounted vertically in the center of the aircraft and one RB.108 mounted conventionally for forward flight. Additionally, the vertically-mounted RB.108s could be rotated forwards or backwards to accelerate or decelerate the aircraft, making transition from vertical to horizontal flight much easier. The SC.1 also had a low-mounted delta wing, the thought being the delta wing would minimise the ingestion of exhaust and foreign objects kicked up by the lift-jets.   Shorts SC.1 VTOL research aircraft. The first VTOL aircraft in the world utilising lift-jet engines. Flying conventionally for the first time in April of 1957 (the first vertical flight would take place a year later), the SC.1 had an additional feature unheard of until that time; it was the first aircraft in the world to utilise a very early, primitive form of fly-by-wire control. A primitive electronic computer took the pilots control input and directed either the bleed-air-powered “puffer jet” reaction controls or the aircraft’s conventional control surfaces to get the desired effect from the aircraft, depending on which of the three control modes it was in, as well as augmenting the stability of the SC.1 while it was hovering; like its predecessors, the SC.1 was extremely unstable while hovering and needed artificial stability augmentation to do so. The SC.1 flew rather successfully for almost ten years (though one of the two aircraft crashed fatally), but as it was solely a research aircraft, it had limited utility beyond that role. More importantly, the SC.1 was demonstrated, with great fanfare, at both the Farnborough and Paris air shows in the late 1950s and early 1960s, and started what can only be described as a craze for lift-jets. Among the nations influenced by Britain’s demonstration of the SC.1, likely no one was more intrigued than the Soviet Union by the lift-jet concept. At the time, the Soviet Union was trying to reconcile the demand for ever-increasing performance from its fighter aircraft with their relatively poor infrastructure to support them. Additionally, much of the top brass in their military arms coveted the idea of a fighter or attack aircraft that could operate alongside their army units. As such, the Soviet aviation industry plunged headlong into the development of lift-jet engines and the aircraft that would use them. First and foremost, they wanted a replacement for the MiG-21. While a decent aircraft by any right, the MiG-21 nevertheless was limited in terms of payload, range and radar while also having rather poor takeoff and landing performance. The replacement envisioned by the Soviet military was to remedy all of these issues in one swoop, using advanced technologies to deliver an aircraft that could do all of this and still be able to fly from small, unimproved runways...or perhaps forego the runway entirely. The first respondent to this requirement was the Mikoyan design bureau, with an aircraft they designated the MiG-23PD. Only this wasn’t the MiG-23 we are all used to...   Mikyoan MiG-23PD prototype. Not a VTOL aircraft, but still utilising lift-jet engines to supplement takeoff performance. Very disappointing performance overall ended the project. That’s right, not only was the first version of the MiG-23 essentially a scaled up MiG-21, it also used two Kolesov RD-36-35 lift-jet engines to help reduce the aircraft’s takeoff and landing run dramatically. Unfortunately, this design was not without its problems, and Mikoyan quickly realised that once the aircraft was airborne, the lift engines were dead weight. Instead of pursuing the lift-jet aided MiG-23, they refocused their effort on building an aircraft with variable-sweep wings; the definitive version of the MiG-23 we see today. Mikoyan wasn’t the only one toying with lift-jets either; Sukhoi’s first stab at the Su-24 “Fencer” all-weather fighter-bomber, known as the T-6-1, used four RD-36-35 lift jets in conjunction with two cruise engines:  Sukhoi T-6-1 prototype. Like the MiG-23PD, it too had very disappointing performance and was abandoned. They too came to their senses when they realised that the four lift engines were dead weight outside takeoff and landing; like Mikoyan, the definitive version of their aircraft would have variable sweep wings. By 1967, the lift-jet was essentially dead in the water at every design bureau in the Soviet Union. All, except for Yakovlev, that is; more on that later. A Seemingly Simple Solution Back in the West, another concept for VTOL was emerging; many designers openly questioned the usefulness of an aircraft with separate lift and cruise engines, as the lift engines imparted a significant weight and volume penalty. The idea was then hatched; instead of tilting the aircraft or using dedicated lift engines, why not tilt the engines and use them for both lift and cruise? Immediately, two companies took leadership designing these aircraft; perhaps not surprisingly, they were both helicopter builders. At the close of the 1950s, Hiller Aviation was one of the leading builders of light helicopters, so it was natural that they would be interested in developing a VTOL aircraft. Proceeding with experimental money from the US Air Force and NASA, Hiller cobbled together a veritable Frankenstein of a research aircraft, the X-18.   Hiller X-18 VTOL research aircraft. The picture below is of the aircraft on its vertical takeoff test stand. With two Allison T40 turboprop engines acquired from the Lockheed XFV-1 and Convair XFY-1 programs combined with the fuselage from a Chase YC-122 transport (the YC-122 was essentially a powered assault glider), Hiller then built their own large, low-aspect ratio wing and a powerful tilt mechanism which would not only tilt the engines, but the entire wing as well. For added lift and pitch control, a J34 turbojet engine was fitted to the aft fuselage. Flying for the first time in 1959, the X-18 met some success, but its flaws became evident in short order. When tilted vertically, the wing acted as a giant sail, pushing and yawing the aircraft in even the lightest of winds. Additionally, the engines were not cross-linked, so if one engine failed in the hover, the aircraft would crash. Handling problems in the transition from forward to vertical flight almost caused the loss of the aircraft, which was permanently grounded after only twenty flights. Regardless of its failure as an aircraft, the X-18 was nonetheless the largest VTOL aircraft that had actually flown, and demonstrated that the so-called “tiltwing” concept was viable...albeit with a lot of refinement needed.  Hiller X-18 in flight. Yes, it actually flew. At about the same time as the X-18 was under development, Bell Aircraft, arguably the world leader in helicopter development at the time, undertook a massive research and development effort to cement themselves as the leaders in VTOL aircraft as well. Two designs emerged from this effort; first was the X-14 research aircraft (which we will cover at a later date), and second was the D-139. Both the X-14 and the D-139 used axially-mounted engines, but that’s where the similarities stop. While the X-14 was a pure research aircraft intended solely to explore the handling characteristics of a vectored-thrust VTOL aircraft, the D-139 was to be a supersonic VTOL fighter aircraft complying with a specification laid out jointly by the US Air Force and the Navy for a supersonic, VTOL day fighter/attack aircraft. Performance targets were ambitious; in addition to the vertical requirement, speeds were to be in the Mach 2+ range and maximum altitude in the area of 50,000 feet – comparable to any conventional-takeoff fighter of the time. What makes the D-139 unusual was its powerplant; instead of several lift engines or thrust vectoring, the D-139 used a single large turbojet engine, like a Pratt & Whitney J75 or a General Electric J79, and a series diverters to divert the exhaust through a series of six small afterburner outlets underneath the aircraft.  Internal layout of the Bell D-139 VTOL fighter concept. Ducting over the engines is for the vertical lift afterburner outlets, located underneath the aircraft. As you might expect with such an outlandish configuration, there were a few problems, such as the fact that there really wasn’t a good way to make it work with its need for complicated diverter valves and piping for extremely hot engine exhaust, plus relying on six afterburners for takeoff and landing would use so much fuel that there would hardly be any left after the transition to forward flight (to say nothing of actually having enough fuel onboard to do anything useful). After being spurned by the Navy, Bell completely revised the D-139 design, abandoning the single engine concept and going with a concept that was rather more conservative, but still unlike anything else out there. Like the D-139, this new aircraft, the D-188, was one of the most ambitious aircraft projects of the late 1950s; at a time when VTOL aircraft were limited to brief hops and very low speeds (to say nothing of their utility beyond that), the D-188 represented a quantum leap in terms of performance; on a typical mission, the D-188 would takeoff vertically, fly as fast as Mach 2 and as high as 50,000 feet out to a radius of 200 nautical miles, fire its weapons and return for a vertical landing.   Bell D-188 VTOL fighter concept. The artist’s impression above is for a late version of the D-188, while the cutaway is of an earlier version. Initially, the D-188 used six General Electric J85 turbojet engines (the same as those in the T-38 Talon and F-5 Tiger); four afterburning J85s were mounted in rotating pods on the wingtips, while two non-afterburning engines were mounted axially in the forward fuselage, with a diverter valve to direct their thrust either aft for forward flight, or downwards at the aircraft’s center of gravity. The aircraft could carry up to 4,000 pounds of payload (in addition to the twin 20-millimetre cannons proposed), making it a somewhat useful tool in combat. The Air Force version was even larger, heavier and faster; the D-188A, as it was known, turned the non-afterburning J85s vertically, and fitted an additional pair of afterburning J85s in the aft fuselage for forward flight only, giving a grand total of eight engines. Speed, range and payload went up as well – top speed of the D-188A was as high as Mach 2.3 and its combat radius was nearly fifty percent greater.  Bell “XF-109” mockup. This is as far as the D-188A ever progressed. The aircraft in the background is a predecessor of the X-22 ducted lift aircraft; more on that in the next part. Ultimately the Navy lost interest in the D-188 and refocused on a version of the Air Force’s D-188A, which Bell proposed would be called the F3L-1 in service. Quite cheekily, Bell also gave the Air Force version of the D-188A the designation F-109, making it an unofficial part of the so-called “Century Series” of fighter aircraft. Unfortunately for Bell, both the Air Force and the Navy lost interest in the D-188A, citing cost, difficulty and lack of range. In addition to that, the D-188A represented a threat to the gigantic nuclear-powered supercarriers the Navy was trying to get funded at the time, so there was definitely a political element to the cancellation of the D-188 program in 1961. Back in Europe, VTOL development was continuing aplomb; seeing a tremendous future in lift-jet construction, Rolls-Royce devised a whole family of lift-jet engines, of which the RB.162 was the first version. Developed jointly by Britain, France, Italy and West Germany, the RB.162 used some extremely radical design features to bestow the engine with a tremendous 19:1 thrust-to-weight ratio; it used reinforced fibreglass compressor cases, and the compressor blades themselves were made of plastic (rather than aluminum, steel or titanium).  Rolls-Royce RB.162 lift-jet engine. One of the most powerful jet engines ever made, pound for pound. The engine also did not have a dedicated oil system either; rather, a dose of oil was shot into the main bearings when the engine was started. The net result of all this was an engine that produced well over 5,000 pounds of thrust out of an engine of roughly the same dimensions and weight as the previous RB.108 lift-jet; all of a sudden, the weight penalty for a lift-jet engine didn’t seem so bad after all. In addition, Rolls’ chief Rival, Bristol Siddeley, had just about perfected the axially-mounted, vectored-thrust jet engine. Having recently abandoned the misguided “Gyroptere” concept, where an 8000-horsepower Bristol Orion turboprop drove four centrifugal compressors with vectoring blower nozzles via a complicated gearbox setup, Bristol’s team finally settled on a new, much less terrifying solution.   Gyroptere engine concept, and a concept aircraft using the engine. Even if you could get all the gearboxes and shafts working without chewing each other to bits, it likely would have never been able to fly. Combining the core of their small Orpheus turbojet with the first three compressor stages of their much larger Olympus, forming a turbofan engine of sorts in the process, Bristol Siddeley then created a novel ducting system to collect and then direct the output of both the fan stages as well as the core of the engine. Dubbed the Pegasus, this new engine along with the RB.162 will come to play key roles in next week’s post... NEXT WEEK: A Brief History, Part Three – Lots of Money Chasing Lots of Bad Ideas
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Jan 28, 2014 09:15
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MAIN POSTS Myasishchev M-4 "Bison" Myasishchev M-50 "Bounder" Sukhoi T-4/Myasishchev M-18/Tupolev Tu-160 "Blackjack" Sukhoi Su-9/Su-15 "Fishpot"/"Flagon" Tupolev Tu-22 "Blinder/Tu-22M "Backfire" Tupolev Tu-128 "Fiddler" Mikoyan-Gurevich MiG-25 "Foxbat"/MiG-31 "Foxhound" Sukhoi Su-27 "Flanker" family Tupolev Tu-95 "Bear" Republic XF-103 and North American XF-108 SHORT POSTS McDonnell-Douglas/General Dynamics F-4X/RF-4X Tsybin RSR Lockheed D-21 HISTORY OF...POSTS VTOL Aircraft, Part One VTOL Aircraft, Part Two
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Jan 28, 2014 09:17
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SyHopeful posted:Dukes of Hazzard Oblast Of course it's going to be a Sukhoi, and an Su-7 at that 
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Feb 2, 2014 05:10
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Slo-Tek posted:Why didn't the L-100 sell? Civilians don't need that much STOL cargo? Price? Ex-military C-130's thick on the ground? Hercules are really uneconomical to fly, end of story. Besides, they're the type of aircraft you'd fly into an airport exactly once up north. First in are some guys in a light aircraft like a Cessna 180 or a Super Cub, who clear a small runway with not much more than hand tools. Next in would be something like a Twin Otter or even a DC-3, which brings in more people and tools, making an even larger runway. Then comes the Herc, which brings in small earth-moving equipment. After that, it's Dash 8s and 737s all day long. Beyond that, the people who currently fly L-100s are too broke-rear end to be able to afford a brand-new $50-60 million aircraft. That much money buys an awful lot of Electras or spare parts/fuel for your old L-100.
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Feb 4, 2014 02:56
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hogmartin posted:Two serious, and seriously stupid questions: First question: The UK actually was the source of the captain/commander/PIC in the left seat and the first officer in the right seat. I'm not 100% sure of the origin of this, but my understanding is it had to do partly with the position of crew stations on conventional ships carrying over to flying boats, which then carried over to land-based aircraft. Edit: The oft-quoted reason of "traffic patterns are generally to the left" and "rules have aircraft passing with the other aircraft off the left side" is more of an effect than a cause, though by now it has become as much of a reason as anything else. Second question: The CF-18 was chosen because it offered the best capability for the best price. The F-16 at the time was not terribly capable in the first few blocks of -A models, which was all there was at the time. Also, the single engine was a source of anxiety, considering the hostile terrain of northern Canada. The F-15 was way too expensive, plus it had virtually no air-to-ground capability (which we needed just as much as an interceptor). The F/A-18 was the only aircraft that offered the capabilities we needed/wanted at the price we were willing to pay. Being a carrier aircraft didn't hamper the CF-18 at all; if anything, its durability was a net plus more than anything. The only changes we specified were the substitution of a conventional Instrument Landing System set, plus the spotlight in the forward left fuselage. We almost bought Iran's F-14s, but after they found out our role in the Hostage Crisis, that deal fell apart. MrChips fucked around with this message at 20:20 on Feb 8, 2014 |
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Feb 8, 2014 20:10
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Slo-Tek posted:At some point some bright boys at the Pentagon also compelled the Navy to take part in the LWF competition, with an eye toward yet another joint-service purchase. So there were designs for an F-16N. The proposed naval F-16 wasn't the F-16N (that was actually a hot-rod lightweight F-16A with a growth engine from a -C), nor was it to be made by General Dynamics. Vought was to be the prime contractor on the naval F-16, with their V-1600 variant. 
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Feb 8, 2014 22:42
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iyaayas01 posted:This fact is hilarious now given how long the CF let the CF-18's air to ground capability atrophy. Even with the current upgrades, our CF-18s aren't even as capable as your average C/D model. Also, this was about the extent of the CF-18s air-to-ground capablity for 20 years:  Looks badass, but it isn't very useful at all.
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Feb 9, 2014 23:00
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FullMetalJacket posted:Which would you rather fly or work on: a piper Navajo or the skymaster? Not a fan of either honestly, but probably the Joe. slidebite posted:That's really interesting, I did not know that. Nope. Put simply, the Navy suffered from a serious case of "We don't know what we want, but we know what we DON'T want" in the VFAX program, and the 1600 was pretty much what they didn't want. It's also one of the reasons why the YF-17 grew so much as it became the F-18. The Vought 1600 also changed so much that it was only superficially an F-16 variant by the final 1602 version. A couple more pictures from the Vought Archives:  
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Feb 9, 2014 23:47
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FullMetalJacket posted:
Are those eyebrows STC'ed or are they an unapproved modification?
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Feb 11, 2014 23:55
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Nebakenezzer posted:Italy can reunite the Italian speaking peoples! Gonna need time to fabricate a claim on Switzerland; can't afford the stability loss if we declare without a CB. (oh god I've played way too much Europa Universalis 4)
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Feb 19, 2014 07:22
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Axeman Jim posted:
The 720 would have had to stop somewhere; Karachi-London is right on the edge of the 720's range with max fuel. Also, that's a Trident 3B, which was actually a wierd-rear end four-engine version of the Trident; in addition to the three Rolls-Royce Spey turbofans, it had an RB.162 as a booster engine, mounted in that spike above the centre engine (and feeding from the centre engine duct). You know, instead of doing the sensible thing and fit larger engines, like Boeing did with the 727 and even Tupolev with the Tu-154...nope, we're going to fit an engine that's going to be dead weight for all but five minutes of the flight!
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Feb 21, 2014 01:26
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Linedance posted:Anyone in the UK who likes Lancaster bombers (and who doesn't?), the Canadian Warplane Heritage Museum will be flying theirs to the UK in August to do a formation tour with the only other one still in existence this summer. And you'll be able to get up close and touchy feely with it (they may even let you fly on it) which I guess you can't do with the British one. Man that trip is gonna take some serious balls. Flying a 70-year-old aircraft over one of the most unforgiving air routes in the world is a pretty daunting task, even if it has been done tens of thousands of times before.
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Feb 26, 2014 00:45
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Nebakenezzer posted:The idea of being a rejected C-5 proposal must sting considering what they went with. The Boeing CX-HLS proposal was vastly superior to the Lockheed proposal in nearly every way; the Air Force would have selected it had Lockheed not deliberately underbid Boeing, only to play the bankruptcy card shortly after and get bailed out by the Pentagon. Lockheed's scuminess has never known any bounds.
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Mar 2, 2014 23:15
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Mokotow posted:So what's wrong with the C-5? Initially, the Boeing CX-HLS had better performance, more cargo capacity/volume (not much, but more nonetheless) and better engines; Boeing heavily favoured what eventually became the Pratt & Whitney JT9D for their design, which in spite of all its problems was still a better engine than the GE TF39 that was ultimately selected for the C-5. All of this unfortunately made the Boeing proposal more expensive than the Lockheed proposal, but the paper performance was good enough that the Boeing aircraft was the frontrunner...that is, until Lockheed deliberately underbid Boeing for the contract. Later, Lockheed ran into huge problems with the design and construction of the aircaft; in fairness, the C-5 was so large and so complicated that problems were inevitable, but because Lockheed had underbid so much, the problems cost so much to solve that it drove Lockheed-Georgia (the semi-independent arm of Lockheed responsible for the C-5) into bankruptcy, which necessitated a hasty bailout from Lockheed-California (the arm of Lockheed we usually think about) and the Pentagon. Schedules slipped and cost continued to rise as the program progressed; originally supposed to fly in early 1967, the C-5A didn't take to the skys until June of 1968. Testing showed more problems with the aircraft; it produced far more drag than expected, which reduced the aircraft's top speed and range considerably. It was also found that the wing was not built strong enough - initial load testing found that the wing would fail at 128 percent of limit load, rather than the 150 percent specified. More fixes were needed (including a primitive aerodynamic load alleviation system using the ailerons), but the fixes added weight to the aircraft...enough that the aircraft soon exceeded the guaranteed weight specified in the contract. Additionally, Lockheed limited the maximum payload of the C-5 to 190,000 pounds, rather than the 225,000 pounds set forth in the contract, in an effort to help with the wing strength problem. As production began in 1970, Lockheed found themselves in even more trouble; the L1011 airliner program was spiraling out of control, and combined with the financial boat anchor that was the C-5, just about drove the entire company into bankruptcy in 1971. Cue more loans from both state and federal governments to get the company back on its feet. The net result of this was that the C-5 had the dubious honour of being the first defense project to experience a billion-dollar cost overrun. As the aircraft entered service, more problems began to crop up. The TF39 engines were, for lack of a better way of putting it, total garbage (not that early models of the JT9D Boeing favoured were any better). The highly complex landing gear of the C-5, designed to allow the aircraft to land on unimproved runways (a feature that to my knowledge has never been used outside of training) and "kneel" to the height of a flatbed truck, was needlessly complicated and as a result was extremely unreliable - over the ensuing years, most of the C-5's reliability problems stemmed from the landing gear. As time went on, the biggest problem with the C-5 was once again the underspecced wing; by the early 1980s, serious cracks started to develop in the wing spars of many C-5As, which led to serious limitations being put on the fleet. Ultimately it was decided to rewing the C-5A with a new, properly designed wing, plus restart production with an improved version designated the C-5B. In spite of the vast improvement that the new wing provided (it was finally strong enough to allow the intended payload capacity), the aircraft was still saddled with most of its troublesome systems; specifically, the engines, hydraulics and landing gear. It wasn't until the ongoing C-5M program that these were finally addressed, with incredible effect - it was found that during testing, one C-5M could do the work of four C-5As or-Bs. MrChips fucked around with this message at 00:08 on Mar 4, 2014 |
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Mar 4, 2014 00:05
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Foxhound-B 
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Mar 6, 2014 21:22
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Madurai posted:Sensible, if this is only an engines-and-avionics upgrade of the MiG-31, but I don't know if there's more to it. That's probably all it's going to be, to be honest. Building a clean-sheet aircraft, especially a clean-sheet aircraft with the mega performance they're claiming, is prohibitively expensive. Best to stick to a proven airframe and modernize it. http://theaviationist.com/2014/03/05/mig-41-mig-31-replacement/ They (meaning RSK MiG Chief Test Pilot Anatoly Kvochur in this case) claim a top speed for the MiG-41 of Mach 4.3...I'd be willing to bet it's capable of Mach 4 much the same way that the MiG-25 was capable of Mach 3.
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Mar 7, 2014 00:50
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Hey if we're going to wildly speculate about what happened my bet is that Hulk did it (In other words shut the gently caress up about terrorism  )
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Mar 8, 2014 18:41
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A Melted Tarp posted:At least locally the plans carrying jumpers announces on CTAF at 5 minutes, one minute and when jumpers are away. You have to be completely oblivious to miss it. That all assumes one is actually monitoring the CTAF frequency. There's always some rear end in a top hat who doesn't.
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Mar 9, 2014 22:15
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holy gently caress this thread has become unreadable I mean its fun and all but jesus christ In light of this, have a video of a dumb guy: https://www.youtube.com/watch?v=JkD9-kFtGec MrChips fucked around with this message at 06:24 on Mar 15, 2014 |
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Mar 15, 2014 06:00
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Saint Celestine posted:So this popped up... and has been making the rounds. Let me put it this way...if you read it on Tumblr, it's probably wrong. Should be their corporate slogan by now. My infoposts will be making their return tonight!
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Mar 18, 2014 01:58
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The Triumph of Thrust Over Gravity (and Sense) – A Brief Acccount of the History of VTOL Aircraft Part Three – Lots of Money Chasing Lots of Bad Ideas With the introduction of a new generation of jet engines in the early 1960s, development of vertical takeoff and landing aircraft gained new impetus. These new engines, such as the Rolls-Royce RB.162 and the Bristol Siddeley Pegasus, were compact, lightweight and very powerful; enough that the prospect of a useable VTOL aircraft was now more than just a concept on some designer’s drawing board. All of a sudden, aircraft companies and militaries around the world began to throw a considerable amount of money at the idea...with wildly varying levels of success. Hawker Builds a Falcon As they were the world leaders in jet engine development at the time, the British naturally enjoyed a considerable advantage when it came time to developing a VTOL aircraft. Additionally, their aircraft builders had conducted more research in this area than anyone else, and they had flown the most successful concepts to date; certainly more successful than the French and American efforts at least. Hawker Siddeley, a large conglomerate made of the most storied names in the British aircraft industry, as well as several other manufacturers of aviation related products, took an early lead in this area. Using their new Pegasus engine, Hawker Siddeley Aircraft’s legendary designer, Sir Sydney Camm, set about the task of building an aircraft to best utilise this new powerplant concept.  Bristol Siddeley Pegasus turbofan engine. As we discussed in the previous part, The Bristol Siddeley Pegasus was a vectored thrust turbofan that evolved out of both the Olympus and Orpheus turbojet engines; the Orpheus drove a section of three compressor stages out of an Olympus, creating what was effectively a turbofan engine. The air driven by the Olympus stages would then be funneled through a pair of nozzles that could rotate through 90 degrees, providing both lift and thrust according to the phase of flight. The concept was not without problems, though; initially, the hot exhaust out of the Orpheus core was not vectored, sending all that energy out the back of the aircraft, and the fan intake was not common with the core intake, which did not allow the fan stages to further boost airflow into the core. Bristol Siddeley realised this and eventually moved to a much larger fan, which both fed the cold nozzles as well as the core of the engine, which in turn had a pair of vectoring nozzles to direct the thrust it generated. Thus, the Pegasus as we all know it was born.  Evolution of the Bristol Siddeley Pegasus engine. The BE.48 was the first concept, while the lighter, more compact BE.52 and BE.53 ultimately evolved into the Pegasus. There were still a few issues; first, the design of the Pegasus meant it needed to be at the exact center of gravity of the aircraft – putting the engine in the middle of an aircraft presents unique challenges in terms of fuel capacity, maintenance and heat management – specifically, how to keep everything around or behind the hot nozzles from melting. Additionally, in spite of the novelty of its concept, the Pegasus was still not a particularly powerful engine; the first Pegasus Mk1 engine put out little more than 15,000 pounds of thrust, and needed a (relatively) large intake area to feed the engine. This meant that whatever the aircraft shaped up to be it was likely to be fairly small and almost certainly subsonic; not ideal from a military planning perspective, but the advantage afforded by VTOL capability was thought to offset many of the disadvantages.  Hawker P.1127 under construction. Regardless of the issues, Camm and his design team worked tirelessly to build an aircraft around this revolutionary new engine. Even the British Government’s 1957 White Paper, which almost completely curtailed British aircraft development in favour of missiles and other novel weapons, did not slow the project down; realising funding would be very short, Hawker approached the Americans for funding to continue work on the aircraft. The general level of confidence in Camm and his team also convinced the Hawker Siddeley board of directors to go ahead and fund the development of two prototypes with company money in March of 1959. Grudgingly, the British government too found some money for the project and by the end of that year drew up a contract for two prototypes of the new aircraft, designated the P.1127. By July of 1960, Hawker delivered the first of these two aircraft for static engine tests.    Top: Hawker P.1127 Prototype. Middle: P.1127 undergoing tethered flight tests at Dunsfold Aerodrome. Bottom: Hawker P.1127 diagram. On 21 October 1960, the P.1127 flew for the first time at Dunsfold Aerodrome, though to call that a first flight is a bit of a misnomer; the aircraft was securely tethered to the ground so that if anything did go wrong the result would be a landing, rather than a crash. A month later, the P.1127 was freed from its tethers and flew freely. By any account, the P.1127 flew rather well; as a conventional aircraft, its performance was every bit a match for the Hawker Hunter, the aircraft the P.1127 was vying to replace, and as a VTOL aircraft it was, well, manageable...not exactly high praise, but at the same time manageable is far better than anything that had come before. That’s not to say there weren’t incidents, though...  P.1127 prototype crashing at the 1963 Paris Air Show. The aircraft did not sustain serious damage and flew again/ Regardless of the relatively poor safety record (the first three P.1127s crashed), the two P.1127 prototypes acquitted themselves well enough to warrant production of an additional four development aircraft, plus a follow-on run of a slightly larger, more powerful version named the Kestrel FGA.1. The Kestrel first flew in 1964, and was intended solely for evaluation by the British, American and West German militaries for its potential as a combat aircraft. Nine Kestrels were built and flown by the Tri-Partite Evaluation Squadron, with six Kestrels later being transferred to the United States Army under the designation XV-6A. The program was a success (though the Germans later withdrew to develop their own aircraft; more on that in a bit) and a further refined version of the Kestrel ultimately became the Harrier we know so well today.  Kestrel FGA.1 in Tri-Partite Squadron markings. Die Bundesrepublik Macht Ein Paar Kackwürste... Buoyed by the miraculous recovery of their economy in the 1950s and 1960s, the West German government felt it was high time that they revitalised their aviation industry, and what better way to do so than with military aircraft? Not only did the newly reformed Luftwaffe had considerable need for new aircraft, but their core strategic thinking at the time was to build an air force around VTOL types; as West Germany was the hypothetical frontline for any confrontation between NATO and the Warsaw Pact, the ability to operate away from airports would allow the Luftwaffe to fight and fly for more than the first few hours of said hypothetical war. Coinciding with their desire to build a new combat aircraft, NATO was drafting something highly unusual; a specification and development contract for an aircraft intended to be operated in large numbers by as many NATO signatories as possible. This so-called “Basic Military Requirement” was not the first of its kind; NATO had previously issued such a specification in the early 1950s for a simple, light fighter/attack aircraft that ultimately resulted in the successful (if a bit crude) Fiat G.91. This new NATO specification, NMBR-3, was rather ambitious; it was for a lightweight, nuclear-capable fighter and attack aircraft capable of supersonic flight and vertical takeoff and landing. Never mind that when NMBR-3 was issued in 1961 the P.1127 had only just demonstrated that VTOL aircraft must *might* be useful after all; no, it’s time to take this show through the sound barrier. Granted, a supersonic VTOL combat aircraft would be a lot more useful and survivable than a subsonic one, but the technical challenge of building such an aircraft is formidable – just ask Bell how their D-188A worked out in the end. Either way, the West Germans pressed on with the project, with Heinkel, Messerschmitt and Bölkow each studying several designs to meet both the Luftwaffe and NATO requirements.    Top: Heinkel He-231 concept early in VJ-101 project. Middle: Heinkel He-231-2 (VJ-101A). Bottom: Messerschmitt P.1227 (VJ-101B). All of these studies are well and fine (with the exception of the tail-sitters that is), but it was becoming patently obvious that none of the remaining West German aircraft companies possessed the resources to see this project through alone. It was then decided amongst Heinkel, Messerschmitt and Bölkow that they would pool their resources and form a joint venture, Entwicklungsring Süd GmbH (or EWR for short), solely to develop this aircraft. Studies were evaluated and compromises were made, with elements from each company being combined into one aircraft; ultimately, a small, six-engined configuration, with two Rolls-Royce RB.145 lift engines in the fuselage and four afterburning RB.145s in rotating pods on the wingtips, was determined to be the best overall choice. The design, designated the VJ-101C, bore more than a passing resemblance to both the F-104 it was intended to replace as well as Bell’s D-188A.   Above and below: EWR VJ-101C. In 1960, EWR built their first test rig, which consisted of little more than a Rolls-Royce RB.108 engine and seat on one end of a long beam, with a weight at the other end. This rig was then held in place from the middle, which earned it the nickname “Wippe” or “see-saw”. The Wippe, while rudimentary, allowed EWR to fine-tune the control system and stability augmentation systems for the VJ-101. The next year, a free-flying hover rig was built, using three engines in place of the final aircraft’s six but maintaining the same weight and balance as the full-scale aircraft. This hover rig too proved invaluable for not only calibrating systems for the VJ-101C as well as for training the test pilots as to what they should expect from the full-sized aircraft.  VJ-101 hover rig, a critical part of the VJ-101C’s relative success. Finally, in April of 1963, the first VJ-101C prototype, X-1, flew for the first time. Though it was a very complicated aircraft, it was reported to fly rather nicely, and proved to be surprisingly easy to fly in vertical mode, thanks to the careful attention given to the aircraft’s autopilot and stability augmentation system. X-1 was joined shortly after by X-2, and the project started to achieve a number of milestones; first transition to horizontal flight, first transition to vertical flight, first takeoff with afterburners and most impressively, first supersonic flight by a VTOL aircraft.  VJ-101C X-2 on telescoping test stand, roasting the ground with its afterburners. Unfortunately, the program was not without setbacks. X-1 crashed in September of 1964 after an autopilot gyroscope was installed backward, causing an uncommanded roll of the aircraft. X-2 continued to fly for many more years, but by 1968 the project came to an end. Not far into the program, the VJ-101C was rapidly succeeded by the VJ-101D as the definitive production aircraft, which was totally different to the –C, calling into doubt the utility of all the testing done up to that point. Additionally, EWR never did solve the issues of using the afterburner for vertical takeoff; instead, they opted for a short forward roll to minimise heat damage to both the aircraft and the runway, technically making the VJ-101C a VSTOL aircraft (VSTOL standing for vertical or short takeoff and landing). Interestingly enough, EWR never did submit their design to NATO for the NMBR-3 competition; by the time the contest began it had become clear that the VJ-101 was not a good fit.  Artist’s impression of the proposed EWR VJ-101D. Very little in common with the VJ-101C. Proceeding roughly in parallel to the VJ-101 program was the second part of the Luftwaffe’s VTOL strategy; that of a small, tactical airlifter to support flights of VJ-101s dispersed to remote locations, ferrying in crews and supplies to keep the fighters in the air. Additionally, the Bundeswehr felt they could find any number of uses for a fast, VTOL transport as well. Adding to the impetus for a VTOL transport was yet another NATO Basic Military Requirement, NMBR-4. NMBR-4 essentially called for a lightweight VTOL theatre transport aircraft to support both ground forces as well as the aircraft to be selected for the NMBR-3 fighter program. The West German government selected Dornier as the development leader for this aircraft, as they were the natural choice; in the years following the war, Dornier had established themselves as a world leader in short-takeoff and landing (STOL) aircraft; vertical takeoff was merely the next logical step. Using two Rolls-Royce Pegasus engines (in the years since the Kestrel flew, the British government effectively nationalised all engine manufacturers under Rolls-Royce) in underwing pods, combined with two groups of four RB.162 lift engines in pods on the wingtips, giving a total of ten engines producing a combined 65,200 pounds of thrust! The Do 31, as it was known, needed every bit of that thrust as well, seeing as it had a maximum takeoff weight of 60,500 pounds, making the Do 31 the heaviest VTOL aircraft even to this day.   Above and Below: Dornier Do 31 VTOL transport demonstrator. Flying for the first time in 1967, three prototypes of the Do 31 were built; E1 was fitted with Pegasus engines only to test the aircraft’s horizontal flight characteristics, E2 was built for static testing on the ground and E3 was built with both the Pegasus engines as well as the RB.162s in place to test vertical flight characteristics. The Do 31 was largely praised by pilots, though it was not without its foibles; the engine controls and the nozzles on the Pegasus engines had to be perfectly synchronised, as even a slight mismatch could send the aircraft careening out of control in vertical mode. Also, the engines would produce such a large cloud of hot gas surrounding the aircraft that depending on aircraft weight and ambient temperature, the engines might not be able to produce enough thrust to abort a landing attempt...you were committed to landing whether you liked it or not.  Dornier Do 31 in flight As with the VJ-101 program, cost and complexity killed off the Do 31 in 1970; I imagine that someone, somewhere in Bonn finally sat up and asked, “Why are we shovelling millions of deutschmarks at an aircraft that is inferior to a helicopter where it matters most?” Sure, the Do 31 promised more speed, range and altitude than a helicopter, but the promised useful load of only three and a half tons could be carried by any number of existing (and much cheaper) helicopters. Not long after the cancellation of the Do 31, NMBR-4 was formally withdrawn as well. ...And so do the French and British! Seeing the potential for some megabuck (megapound? megafranc?) orders connected with NMBR-3, the French and British began work on their entries into the contest. The French, being as they are, looked up from their croissant and Gitanes break, shrugged, penciled in a bunch of Rolls-Royce lift engines into the existing Dassault Mirage fighter and called it a day. OK, it wasn’t that simple, but basically Marcel Dassault (who was still working at his company at the time) took his wildly successful and wildly beautiful Mirage III fighter (the example modified happening to be first Mirage III prototype), modified the fuselage and filled it with eight RB.108 lift engines while at the same time replacing the SNECMA Atar engine with a non-afterburning Bristol Orpheus turbojet for horizontal propulsion. The resulting aircraft, named the Balzac V, flew for the first time in October of 1962. The Balzac was a troublesome aircraft from the get-go; unlike the VTOL attempts made by others, it was thought that the engine configuration of the Balzac made it stable enough to not need more than a rudimentary reaction control system. This sadly proved not to be the case, as the single Balzac fatally not once but twice in three years. The second fatal accident exposed one of the chief difficulties with using large numbers of lift engines; that being an interruption of fuel flow and the consequences thereof.   Dassault Balzac V VTOL fighter testbed. Learning some hard lessons from the Balzac, Dassault regrouped and came back with a much revised design. Taking the basic design of the Mirage III, Dassault added a 10-foot stretch to the fuselage, which allowed them to incorporate more fuel as well as a much more powerful horizontal flight engine; the SNECMA TF104, a non-afterburning modification of the Pratt & Whitney TF30 turbofan. The added weight of all this meant that Dassault also had to switch to eight of Rolls-Royce’s lighter and more powerful RB.162 lift jet engines.   Above and below: Dassault Mirage IIIV, the much improved VTOL fighter proposal. This new aircraft also carried a proper Mirage name as well, the Mirage IIIV. Performance was promising; not long after its first flight in February of 1965, the Mirage IIIV went supersonic for the first time, and demonstrated a successful vertical takeoff and transition to horizontal flight, then back to vertical flight and a successful vertical landing...the only problem is, it was never able to do both supersonic flight and vertical flight in the same mission. A second prototype was built, this time with an afterburning TF30 (called the SNECMA TF306), allowing the Mirage IIIV to exceed Mach 2, making it faster than any aircraft (theoretically) capable of vertical takeoff and landing, even to this day. Unfortunately, the crash of the second Mirage IIIV essentially spelled the end of the program, plus the squabbling about which country preferred what at NATO was starting to put the entire NMBR-3 program in doubt, but not before the British failed even more spectacularly with their entries. Being the leaders in successful VTOL aircraft (with all of one aircraft type that could be considered as such), the British were looked upon as the initial favourites in the NMBR-3 competition, and their proposal didn’t disappoint. Hawker took the basic design of the P.1127 demonstrator and refined it considerably, giving it squared off, variable area inlet ramps and better aerodynamics in the nose. Designated the P.1150, this aircraft would have given a noticeable improvement to the P.1127’s performance, but it unfortunately did not prove to meet the performance criteria set forth in NMBR-3. As the Pegasus was nearly tapped out at the time, a radical new engine was clearly needed, along with a further refined airframe to carry it. Hawker’s partner Bristol Siddeley took the basic concept of their Pegasus engine and scaled it up significantly, creating an engine, called the BS.100, with nearly double the power of the largest version of the Pegasus at the time. Beyond that, the BS.100 was to utilise a feature called “plenum chamber burn” (PCB), in which fuel is burned in the forward “cold” nozzles of the engine much the same way an afterburner works in the hot exhaust of a more conventional engine, increasing thrust of the engine to nearly 36,000 pounds – two and a half times more than the existing Pegasus versions could manage.   Top: Bristol Siddeley BS.100 vectored turbofan. Notice the heat shield behind what would be the cold nozzles on a Pegasus engine. Bottom: Harrier GR.1 XV798 serving as the testbed for the Bristol Siddeley BS.100 engine. While it sounds simple, PCB posed several technical challenges, such as how to adequately control airflow through the engine with and without PCB running (the solution ultimately was found to be tiny little variable-area nozzles) – hell, even the ignition system for PCB was a huge challenge. Nevertheless, Bristol was able to overcome these challenges with their BS100 engine, which was run frequently from 1960 onwards.   Above: Artist’s impression of Hawker P.1154 in Royal Navy service. Below: Hawker P.1154 diagram. This new airframe and engine combination, designated the P.1154, had all the makings of a successful aircraft; the performance was stellar, combining a top speed of nearly 1,200 miles per hour, a much longer range than the P.1127/Kestrel as well as far greater payload capacity...so great was the P.1154 that it was favoured to be the prime production aircraft that derived from the original P.1127. Unfortunately for Hawker, When the Labour Party was elected to government in 1965, they ordered a stop to nearly every aircraft project ongoing in the United Kingdom (save for Concorde, but they would have cancelled that too were it not for fear of causing an international incident), of which the P.1154 was one; instead of a potentially world-beating aircraft, the British ultimately decided to purchase F-4 Phantoms for the Royal Navy and Royal Air Force. Work stopped at once on the P.1154, though much later on, the lessons learned with the P.1154 (especially in the area of the engine) made their way with great effect into the ultimate successor to the P.1127, the Harrier. Coming Soon: A Brief History Part 4 - Everyone Loses Their Minds (Especially the Soviets)
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Mar 18, 2014 07:41
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MAIN POSTS Myasishchev M-4 "Bison" Myasishchev M-50 "Bounder" Sukhoi T-4/Myasishchev M-18/Tupolev Tu-160 "Blackjack" Sukhoi Su-9/Su-15 "Fishpot"/"Flagon" Tupolev Tu-22 "Blinder/Tu-22M "Backfire" Tupolev Tu-128 "Fiddler" Mikoyan-Gurevich MiG-25 "Foxbat"/MiG-31 "Foxhound" Sukhoi Su-27 "Flanker" family Tupolev Tu-95 "Bear" Republic XF-103 and North American XF-108 SHORT POSTS McDonnell-Douglas/General Dynamics F-4X/RF-4X Tsybin RSR Lockheed D-21 HISTORY OF...POSTS VTOL Aircraft, Part One VTOL Aircraft, Part Two VTOL Aircraft, Part Three
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Mar 18, 2014 07:41
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hackbunny posted:This designation hurts my head A little bit, but calling it the "Mirage 3V" just doesn't work either. Madurai posted:Important side note about the P.1154 (the "real Harrier"): it would have gotten a lot closer to production had the RAF and RN not gone to fisticuffs over requirements for the new plane. Unable to afford two versions, and unable to rationalize the engineering behind making one plane do both jobs, neither service got one. Probably, in hindsight, for the best. The RAF-RN slapfight over the P.1154 is absolutely one of the big reasons why the project got cancelled (and why it's cancellation remains one of the most contentious cancellations anywhere); I sort of glossed it over partly because my post was running long, and partly because it would take an entire infopost to tell the story of the final implosion of the British aviation industry in the 1960s.  To make paraphrase the P.1154 story, the RAF wanted a supersonic fighter-bomber; basically, a supersonic VTOL follow-up to the Hawker Hunter. The Royal Navy, on the other hand, wanted a jack-of-all-trades aircraft with emphasis on interception; what they wanted was what they got in the end...the F-4 Phantom. As such, the Royal Navy wanted a large, two-seat aircraft with a big radar, while the RAF wanted a single-seater without a lot of complicated avionics. Even though they were initially enthusiastic for the P.1154, the Royal Navy soured on the deal when the saw the proposed aircraft; all along, they secretly wanted a CATOBAR aircraft, which would help them secure funding for the replacement for HMS Ark Royal. Since the P.1154 wasnt CATOBAR capable, it would make funding the new carrier a rather difficult sell. Ironically, the Navy never did get their funding for the new carrier either; my guess was they pissed off too many people by abandoning the P.1154 and selecting the F-4 instead. MrChips fucked around with this message at 00:58 on Mar 19, 2014 |
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Mar 19, 2014 00:51
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E4C85D38 posted:Basically everything in the US military runs on JP8, from kitchen stoves and space heaters to main battle tanks, ground vehicles with diesel engines, generators, and so on. The DoD justifies the cost because it simplifies logistics a lot. Instead of having to get ten or twenty kinds of fuel to a unit through god knows how many pipelines and keeping track of all of them, you just throw a whole bunch of JP8 at it. You're all talking like jet fuel is expensive or something? Apart from bunker fuel, jet fuel is about as cheap a petroleum fuel as there is.
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Mar 20, 2014 23:54
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Passengers start screaming at about 1.5 g, so it's adventageous to keep it below that. That works out to a ~45ish degree level, banked turn. Most airlines will yell at you for exceeding 30-40 degrees bank angle without good reason to do so, and ~20-25 degrees pitch angle as well. The big driving factor for aircraft limit loads are wind gusts; the 2.5g certified load factor for an airliner corresponds to an 80 foot-per-second wind gust (with ultimate load factor corresponding to a 120 fps wind gust). 80 fps is really high, but not uncommon in something like a thunderstorm.
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Mar 21, 2014 01:10
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Mr. Samuel Shitley posted:Holy poo poo, how are they planning on machining a 10-foot fan in a single piece? For large airliner engines, blisks are typically only used for compressor stages; the fan is going to be a bladed hub for a long time, the reason being is that the general consensus right now seems to be that the fan blades should be a carbon-fiber/titanium composite mix as we see in the GE90/GEnx and the PW1500G. Even Rolls-Royce, who have stubbornly stuck with hollow titanium fan blades for many years now, are starting to warm to the idea of a composite blade once again (after it went so badly the first time around in the original version of the RB211). Also, blisks are unlikely to be found in the turbine section of a large engine either, barring a major jump in materials or construction technology; the cooling needs of the turbine blades require all sorts of very complicated air passages within each blade that would be next to impossible to create in a blisk-type sturcture. Now in a small engine (of a size appropriate for a corporate aircraft), I can see blisks being used in nearly every stage of the engine, including fans and turbines.
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Mar 22, 2014 02:21
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Understeer posted:And the turbine blades of tomorrow won't even be metal. Eh, ceramic turbine blades have been five years away for the last thirty years or so. Partly because they're expensive as all hell, partly because they don't offer a huge improvement in thermal performance over existing air-cooled nickel alloy blades, partly because they're really brittle and also because they don't expand and contract at the same rate as the metal case, which leads to sealing issues at high temperatures. The one big area they do have an advantage, however, is weight...but again, it isn't enough to offset the disadvantages for now.
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Mar 22, 2014 18:08
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| # ¿ Apr 26, 2024 02:05 |
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Who wants to start a drone company with me so we can live large on Silicon Valley funny money? I'm thinking along the lines of drone-delivered pet food...
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Mar 29, 2014 17:13
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