Thursday, July 30, 2015

Pervertiplanes: A Forgotten Argot Of Aeronautical Engineering?

Even though the term dates back to the Cold War era 1960s American aeronautical engineering boom, does anyone still use the term “pervertiplane” these days? 

By: Ringo Bones

Any group of specialists has its own private lexicon and aeronautical engineers are surely no exception. The word “pervertiplane” could be defined as a corruption of the term “convertiplane” – which is a contraction of the term “convertible aircraft” – pertaining to aircraft constructed in such a way that their lifting and propulsion systems may be converted to permit efficient operation either for vertical take-off and hovering or for high-speed forward flight. Such craft are now more commonly termed as VTOL or vertical take-off and landing aircraft. 

Convertiplanes – at least their experimental prototypes – began life back in the beginning of the 1960s. Examples of which are the X-19 broad-bladed tilting rotor turboprop VTOL plane, the X-22 tilting ducted fan VTOL plane, or was it the XC-142A, which is probably the great-granddaddy  of the V-22 Osprey that got fielded back in 2007 and some jet-engine high-performance experimental VTOL fighter planes like the British-built Hawker P1127 cascade vane-nozzle turbojet VTOL that later became the USMC’s Hawker Siddeley Harrier / Harrier Jump Jet and the then West German EWR VJ-101C tilting engine turbojet VTOL interceptor. 

Convertible aircraft are sometimes called “convertiplanes”; however, one prominent aeronautical engineer – legend has it that it was Igor Sikorsky – has suggested the name “pervertiplanes” because so many of the machines, in his view, combine the worst features of the helicopter and the fixed-wing aircraft. The necessary provision of such structurally difficult features as tilting wings, tilting rotors, cascade-vane assemblies and the like which may be subjected to high gas temperatures and periodically fluctuating air loads, all at minimum structural weight, leads to the development of very complicated mechanical devices that in turn leads to a high probability of mechanical failure. 

By far, the most serious problem with convertible aircraft lies in its characteristics following engine failure at low altitude. Unlike fixed-wing aircraft, which can fly as a glider following engine failure or the helicopter, which can descend at a safe – but rapid – rate with its rotor being spun by the flow of air past it (a process called autorotation), the convertible aircraft commonly lacks wings large enough to descend slowly as a glider, or a rotor large enough to permit a safe autorotation descent. Worse yet, if power failure occurs during transition, it may not be possible to achieve either type of descent and the vehicle will fall like a rock. Looks like a convertible aircraft or convertiplane’s reputation as a “pervertiplane” seems apt.  Or should we also include L7 guitarist Donita Sparks’ battered Gibson Flying V which she christened as the “flying vagina”?

Sunday, July 19, 2015

The V-22 Osprey: A Pervertiplane?

Does the V-22 Osprey deserve the name pervertiplane because it combines the worse features of the helicopter and fixed-wing aircraft?

By: Ringo Bones 

If New York Times Bestseller List literary phenom E.L. James was an avid aviation enthusiast, James would have chosen to use the V-22 Osprey as the private plane for Christian Grey – the young billionaire business magnate and lead character of Fifty Shades of Grey due to the “perverted” nature of how the V-22 Osprey works aerodynamically. But does such family of aircraft deserve such disparaging label? 

Back in the beginning 1960s, where the granddad of the V-22 Osprey and related aircraft were at their development stage, one prominent aeronautical engineer (Igor Sikorsky?) has suggested the name “pervertiplanes” because so many of such machines – in his view – combine the worst features of the helicopter and the fixed-wing aircraft. The necessary provision of such structurally difficult features as tilting wings, tilting rotors, cascade vane assemblies and the like, which may be subjected to high gas temperatures and periodically fluctuating air loads, all at minimum structural weight, leads to the development of very complicated mechanical devices. The complication of these devices, in turn, leads to a high probability of mechanical failure. 

Ever since Bell Helicopter and Boeing Helicopter was awarded the developmental contract by the US DoD for the V-22 Osprey tiltrotor type aircraft back in 1983, engineering problems of such aircraft that were uncovered back in the 1960s were tried to be “engineered out” via the use of newly mass-manufactured ultra-lightweight ultra-strong composites 1980s era composite materials. The USMC began training crews for the Osprey back in 2000 before its kinks were finally ironed out and its first long-delayed rollout in 2007 as a replacement of its ageing heavy lift helicopters that date back from the 1960s – i.e. the USMC’s fleet of Chinooks and CH-46 Sea Knight fleet.  

Back in October 2007, Time magazine ran an article condemning the V-22 Osprey as unsafe, overpriced and completely inadequate. Given that composite materials make up 43 percent of the Osprey’s overall airframe – and composite materials aren’t exactly cheap – Time magazine may have been correct about the high cost issue of the Osprey. Safely-wise, during its testing phase from 1991 to 2000, there were four crashes that resulted in 30 fatalities. Since becoming operational in 2007, the V-22 Osprey has had 3 crashes that had resulted in 6 fatalities and several minor incidents. The aircraft’s accident history has generated some controversy over its perceived safety issues. Given the aircraft’s history, fictitious billionaire-sex-pervert Christian Grey would probably, in his right mind, steer clear away from using such “pervertiplanes” such as the V-22 Osprey as his main private plane / corporate aircraft. 

Saturday, July 18, 2015

Empty Leg Flights: Champagne Flavored Air Travel At Beer-Budget Prices?

Even though we the 99-percent can only dream of owning our very own private jet, is there a way to experience flying in one on the cheap? 

By: Ringo Bones 

Unless you are a 1980s era legacy rock star, billionaire business magnate, A-List Hollywood actor / movie producer types, etc. we, the 99-percent, can probably only dream of travelling by private jet and so overwhelmingly most of our experiences of flying commercial airlines will undoubtedly involve brutal early morning check-ins, the enforced surrendering of toiletries to airport security – or TSA in the United States – to scowling customs officers and – always a certainty – delays. But, like they say in contemporary cold medicine commercials, there’s another way – one that also happens to be substantially better in every detail. Basically, you need to get yourself to one of those “empty leg flights”. 

Empty leg flights are private jet flights where there happens to be nobody onboard, at least not until you come in and the good news is on short and intermediate range flights, you are paying at almost the price of flying coach in a typical commercial airline flight.  Private jet charter firms, realizing that their aircraft have to return to base after they have ferried the first client to somewhere swanky at some point, have taken to offering these return “empty leg flights” for cut-price rates. It is only logical that these private jet charter firms make some extra money out of someone’s one-way trip and the consumer gets a cut-price private jet experience and the flexibility to just show up 15 minutes before take-off, get right on board and fly. 

Free champagne and swanky caviar-filled catering will be available as standard on an empty leg flight says Mehdi Dialmy of Privatefly, one of the private jet charter firms providing empty leg flights. If Privatefly does it this way, undoubtedly, their competitors will also pamper their empty leg flight clients to attract customers. But timing is the key for availing such budget-priced luxurious civil aviation indulgencies. 

Friday, June 12, 2015

Wither Human Powered Flight?

Is the future of purposeful human-powered flight, recreational or otherwise, a non-starter? 

By: Ringo Bones 

Back in June 12, 1979, It seems that the “dawn” of human-powered flight was already at hand when Bryan Allen, pedaling continuously for 2 hours 49 minutes, became the first pilot to successfully cross the English Channel under his own power via the first “man-powered airplane”, the Gossamer Albatross. Unfortunately, when the 1980s came and went, the United States’ Federal Aviation Administration never issued guidelines and licenses for “recreational man-powered aircraft”. Given the aeronautical engineering challenges, is human-powered flight a non-starter due to the low power-to-weight-ratio of the “human machine”? 

Bryan Allen’s Gossamer Albatross flight back in June 12, 1979 may be the most successful demonstration of human-powered flight given that none comparable attempt had happened since, but mankind has successfully flown before under his own power some years before. Back in 1962, John Wimpenny holds the international record for successfully flying a specially designed aircraft for more than half a mile in which he himself was the engine. 

John Wimpenny’s dream of a “human-powered flight” was first given impetus back in 1959 when a British plastics manufacturer named Henry Kremer offered a UK £5,000 prize for the first successful flight of an aircraft based on a human propulsion system. In November 1961 a group of aircraft engineers and technicians headed by Whimpenny completed construction of a plane which they christened the “Puffin”, built primarily of wood and covered with plastic skin. Fundamentally, it was a cross between an airplane and a bicycle because the “cockpit” enclosed a single-wheel cycle; the pilot pumped the pedals, turning the wheel for takeoff momentum and at the same time spinning the propeller for in-flight thrust. 

On May 2, 1962, Whimpenny, who had warmed up for the flight by cycling 5 miles to work every day for 2 years took the pedal-powered Puffin to an altitude of 8 feet and traveled for 993 yards. The flight set a record, but won no prize because the contest specified a longer flight and a figure-8 course. Although Kremer has since upped the prize to UK £10,000 since Wimpenny’s 1962 attempt, the “Kremer Prize” still awaits a winner. 

Tuesday, May 26, 2015

250 Miles-Per-Hour: The Top Speed Of The Conventional Helicopter?

Is the “conventional” main-rotor-and-tail-rotor helicopter forever limited to a top speed of 250-miles per hour?

By: Ringo Bones

Ever since Igor Sikorsky perfected his main-rotor-and-tail-rotor helicopter configuration during the latter half of the 1930s many overly-optimistic inventors inspired by him have pushed forward to design a generation of helicopters capable of ever higher speeds. But is 250 miles per hour or even 300 miles per hour the ultimate speed limit of the “conventional” main-rotor-and-tail-rotor configuration helicopter?

By the laws of aerodynamics, the relationship between the helicopter’s top speed and its maximum rotor speed obey the “law of threes” – that is the maximum tip speed of the helicopter’s rotor is three times the maximum forward speed of the helicopter. And by the laws of physics, as the main rotor’s tip speed approach and exceed the speed of sound – its lifting efficiency drops off like a rock off a cliff. Remember that 1980s TV series called Airwolf about a helicopter capable of flying faster than the speed of sound? I wonder how many helicopter designers worth their salt had ridiculed the idea due to its physics-defying premise. And despite the mechanical complexity of a “Sikorsky-style” main-rotor-and-tail-rotor helicopter configuration, 97-percent of existing helicopters flying today opt for this design because it is currently the simplest to manufacture from the company’s perspective and most economic to maintain.

During the Vietnam War, Lockheed managed to design a helicopter capable of flying 250 miles per hour or 400 kilometers per hour in level flight called the Lockheed Cheyenne. It consists of a tail rotor that intermeshed with a pusher propeller. In its maximum forward speed, only 25-percent of the main gas turbine engine’s power goes to the main rotor as the rest is diverted to the pusher propeller. Despite being called a “compound helicopter” as opposed to a true helicopter, the Lockheed Cheyenne never went to service in the Vietnam War theatre due to its “mechanical complexity” might cause problems to ground crews and it is somewhat pricier than the next fastest helicopter of the time – the slightly slower Huey Cobra. And despite their popularity with the world’s various military organizations, there are spots cars today priced around 50,000 US dollars that can run faster than the Apache Longbow helicopter gunship – and top of the line 270 mile-per-hour capable supercars from Lotus and Ferrari can easily left the Huey Cobra in the dust in a quarter-mile drag race because the Huey cobra only has a top speed of 230 miles per hour.

During the early 1970s, helicopter aerodynamicist Peter Wilby together with Geoff Byham developed the swept-back paddle helicopter rotor tip. They manage to come up with the design to “wring more speed” from the conventional main-rotor-and-tail-rotor helicopter design by trial and error methods because they don’t trust previous existing mathematical helicopter main rotor analysis that had gone before – despite these being obtained via the most advanced mainframe computers available at the time. But the work of Wilby and Byham later paid off when their then unusual swept-tipped / swept-back paddle helicopter main rotor configuration were tried out on the Westland Lynx back in 1986 that allowed it to achieve the Guinness Book of World Records’ adjudicated world helicopter speed record of 249.1 miles per hour that stood until today as a fastest speed for a true helicopter.

So what is the future of the helicopter when it comes to pushing the top speed envelope? Well, engineers at Sikorsky had recently developed the X-2 experimental helicopter that achieved the unofficial world speed record of 288 miles per hour. But many “helicopter” purist wonder if Sikorsky’s X-2 is still a “conventional” or “true” helicopter because despite of using the contra-rotating main rotor configuration to cancel out torque, it uses a 6-bladed pusher propeller to achieve such speeds. The X-2 uses a fly-by-wire control system and computer assists to help stabilize the craft and also allows it to outmaneuver existing attack helicopters. Ultimately, the Sikorsky X-2 prototype will be the basis of the upcoming Sikorsky S-97 Raider and despite the S-97 Raider still has no working prototype other than the proof-of-concept X-2, the S-97 Raider can easily fly faster than 250 miles per hour when fully loaded with ordnance and can fly backwards at over 100 miles per hour.        

Tuesday, March 31, 2015

Mentally Unstable Flight Crew: The Bane of the Airline Industry?

Given the recent tragic Germanwinds Flight 4U9525 crash, has mentally unstable flight crew become the greatest threat of the airline industry?

By: Ringo Bones

Forget religious extremists undertaking brazen 9/11 like attacks using airliners it seems that mentally unstable pilots and flight crew now represent the greatest threat to the complacency of the airline industry. Although air travel is still the safest form of travel on an accident per miles traveled basis, rare flukes like mentally unstable flight crew that the preliminary investigation uncovered was the cause of the recent tragic Germanwinds Flight 4U9525 crash back in Tuesday, March 24, 2015 where the co-pilot with alleged mental health issues named Andreas Lubitz was the ongoing suspect as the cause of the crash when he deliberately locked out the pilot from the cockpit and deliberately crashed the plane on a steep mountainside near Seyne-les-Alpes, France that resulted in the death of 150 people. As a 25 year old plane, the Germanwings plane that crashed was an Airbus A320 – the model that’s been a workhorse of the civilian aviation industry known for its exemplary safety record and reliability.

The only other comparable high-profile pilot suicide / deliberate crash incident was the findings of the tragic October 31, 1999 crash of EgyptAir Flight 990 when the plane’s remains was found 0 miles east of Nantucket Island in the Atlantic Ocean that resulted in the tragic loss of 217 lives. Relief first officer Gameel Al Batouti – a veteran pilot of the 1967 Six Day War and the 1973 Yom Kippur War was the prime suspect of the cause of the crash of the EgyptAir Flight 990. 

Rigorous screening of prospective pilots and flight crew may be the solution but the powers that be at IATA had been warning of a pilot shortage as early as next year, given that the airline industry had been expanding at its fastest rate since the 1980s despite of 9/11 and the 2008 global credit crunch. Could the safest form of travel poised to become less safe? With the tragic deaths of German children coming back from a field trip in Spain, the greatest impact of the Germanwings Flight 4U9525 tragedy is probably the Bayreuth Wagner Opera where the lost of bass baritone Oleg Bryjak and contralto Maria Radner could put a damper to opera fans lining up to an opera venue with a global prestige where the waiting period for tickets could be as long as ten years. This is indeed a tragedy of epic proportions.      

Sunday, March 8, 2015

Are Vintage Piston-Engine Planes Still Airworthy To Operate?

Are vintage piston-engine aircraft still airworthy to operate this day and age given that the gasoline used to power them is no longer manufactured? 

By: Ringo Bones 

When Hollywood actor Harrison Ford crash landed his World War II era vintage trainer Ryan PT-22 Recruit on a Los Angeles golf course back in Thursday, March 5, 2015, though he suffered gashes on his head and was described in fair to moderate condition when brought to the Ronald Reagan UCLA Medical Center. Given the situation could have easily turned tragic, I know wonder if vintage piston-engine planes are still airworthy to operate given that the gasoline that was used to fuel them are no longer currently manufactured by oil companies? 

After Clair Cameron Patterson managed to raise awareness of the dangers of tetraethyl lead in gasoline and the subsequent phase-out of such fuel additives by the mid 1970s, it meant the death knell of piston engine planes that are not economically viable enough to be fueled by aviation gasoline whose octane ratings are boosted by non-lead based additives. This is the primary reason why the first piston engine plane to become commercially viable enough to operate by ferrying paying passengers alone – i.e. the Douglas DC-3 – virtually vanished and was considered extinct by the mid 1980s. 

At about the same time of the golden age of aviation – i.e. civilian barnstorming – during the 1920s, tetraethyl lead was mixed with gasoline as a patented octane booster that allowed piston engine compression to be increased substantially which in turn resulted in increased vehicle performance and fuel efficiency. Sadly, the lead free aviation gasoline developed after the tetraethyl lead ban – even though good for everyone’s health - proved to be too corrosive to the piston and combustion chambers of the piston engines used in the Douglas DC-3 had resulted in the slow death of these iconic planes that by the mid 1980s, their engines are operated into destruction with lead free aviation gasoline. Unlike gas turbine engines that can be fueled with anything that burns – like fake Chanel No. 5 – and will still run.