Bing’s views do not represent that of this site, or the Navy or the Church of the Wyvern

As a brief primer for the lesser mortals in the audience: in a helicopter the stick between the pilot’s legs is called the cyclic. This alters the pitch of the blades as they revolve around the mast, cyclically you could say, which allows the disc to be tilted in any direction moving the thrust vector accordingly. The handbrake-like lever to the left alters the pitch of all the blades collectively, hence it’s imaginative name of the collective, this will increase or decrease the amount of thrust broadly speaking allowing the aircraft to go up or down. Note this is unlike most cheap quadcopter type drones which vary the rotor RPM to climb and descend. Finally, the yaw pedals in the footwell provide somewhere for the pilot to rest their feet and if the urge takes them rotate the helicopter around the rotor mast by varying the pitch on the tail rotor blades. Obviously that final part doesn’t apply to something like a Chinook which doesn’t have a tail rotor and it has to be assumed is manoeuvred by witchcraft. Or differential vectoring of the two rotor discs. So probably the witchcraft thing. To be clear this is a gross simplification and if you want to know more about how to fly a helicopter read ‘Chickenhawk’.

The ten aircraft below have unfortunately let the side down and generally suffer from being poorly designed, used for the wrong role, being overly ambitious or some combination of all three.

The 50s were a time of great advances in aviation, the Percival P.74 was responsible for none of them. Looking as if the company’s designers were tasked to make a workable helicopter from a drawing by the director’s three-year-old child it featured a bulbous fuselage with tiny wheels and a comically out of proportion tail rotor. Presumably feeling there was nothing left to lose it was decided to power it by using tip-jets to drive the rotors and control their pitch with full-span trailing edge ailerons. The observant reader will notice both these features have failed to make it into widespread production. Or even into a niche.

To provide air for the tip jets two Napier Oryx gas turbines drove air compressors the combined exhausts from both turbine and compressor then being ducted to the rotor tips. As someone had decided to put the engines in the belly this involved large ducts of hot air going up either side of the cabin, splitting it in two. Probably kept it warm though. More worryingly the only access to the cockpit was through the gap between these ducts, the sole door being at the back of the aircraft.

After five years of development, and presumably the delight of the test pilots, the first flight was aborted as despite the efforts of all involved it failed to leave the ground. Despite further tinkering with the engines to produce more gas flow the P.74 never left terra firma and was eventually wheeled across the airfield and forgotten about. As if to make sure all traces would be forgotten, shortly afterwards the Percival name was replaced with that of Hunting.

Proving that it wasn’t just the British that could pursue aviation’s dead ends the XH-17 also featured tip jet driven rotors. At which point any similarity with Percival’s attempt ends. Starting life as a rotor test rig under the auspices of the Kellett Aircraft Corporation the XH-17 ducted bleed air from the compressor sections of two GE J35 jet engines. After travelling 65’ to the ends of the oversized rotor blades fuel was added to the airflow and ignited giving four distinct jet plumes in the trailing edge. And a noise signature like an AC/DC concert, complaints being received from eight miles away.

In June of 1948 facing financial issues Kellett sold the XH-17 and their interest in the programme to the only company mad enough to take it on. The one run by a man who watched movies for four months, while not cutting his nails, storing his urine in bottles, and without their even being a global pandemic. Yes, the Hughes Aircraft Company. [1]

After finding a pilot willing to fly the XH-17, one Gale Moore, the first intentional flight took place on 16 Sep 1952 at which point Moore discovered the control balance was ideal for a rotor test rig. [2] Unfortunately, it was less useful for any fine control the beast bouncing up and down until Moore managed to dump it onto the ground firmly enough to stay there. After some tinkering Hughes managed to resolve the control issues and the XH-17 entered an intensive 10-hour test programme, at which point the rotors fatigue life was used up.

Although there was a proposal for a four bladed production version of the XH-17, the XH-28, the Army eventually decided not to pursue it. There presumably not being a massive requirement to move tanks across the battlefield at 70knots while being heard by everyone in the same county.

Despite this inauspicious start Hughes would go on to produce some half decent helicopters you may have heard of. Such as the Apache.

[1] The author once worked for an oil field services company that was taken over by the Hughes Tool Company. It was not as eccentric as he hoped.

[2] The first unintentional flight having occurred 2 years earlier when a control link broke and resulted in the rig part, but oddly not the rotors, having to be rebuilt.

This is almost definitely a helicopter and was evaluated by the US Army as part of their plans to kill their own soldiers in new and imaginative ways. Eschewing such fripperies as a fuselage, seats, or actual controls the HZ-1 was steered by the ‘pilot’ leaning in the direction he wanted to go. For those wondering if they can build one in their own garage [3], the most complicated bit, the engine, was a converted Mercury outboard motor so the answer is probably yes. This drove two 15’ diameter contra-rotating rotor blades that, in two fingers to occupational health and safety, were placed below the sacrificial offering. In the pros column in trials soldiers learnt to fly it with only 20 minutes of instruction, before speeding across the landscape at up to 75 mile an hour. Although with a range of 15 miles it’s not obvious that was particularly useful.

In the cons column the HZ-1 suffered two accidents, apparently non-fatal, where the contra-rotating blades clipped each other and then stopped working. More worryingly NACA were unable to repeat the phenomena in their wind tunnel, proving that even rocket scientists don’t understand helicopters. Combined with a rare outbreak of sanity in the US Army, who realised there wasn’t actually a lot of utility to the personal helicopter idea, this led to the end of the programme.

[3] For legal reasons Hush Kit does not advise this, but if you do, please mention us in the inevitable YouTube video of your demise.

Despite having to remove the doors to meet the range requirement when carrying a WE177C depth charge the Westland Wasp manages to avoid being on this list due to probably being the only ASW helicopter to have actually damaged a submarine. Which makes you ask what the rest of them have been doing with their time. The Agusta A-106 however does not have that advantage.

With a max take-off mass lower than the Wasp’s empty weight the A106 was truly dinky, at 1400kg fully loaded it probably weighed less than your car. This almost anorexic look was achieved by only providing seating for a pilot while two Mk44 torpedoes could be hung under the fuselage, at which point you have to ask how much of the 800kg payload remained available for fuel. The absence of any other crew would have limited the A106 to carrying its payload where it was told to and then dropping it. Hopefully someone would then be available to tell the pilot how to get back as well, photos of the cockpit showing it to be remarkably lacking in avionics. It’s at this point you start to wonder if Agusta realised they had created a manned version of the QH-50 DASH torpedo carrying drone which had already entered service two years before the 106’s first flight in 1965.

Although some sources claim it had an acoustic submarine detection system it’s not obvious where this would have gone, nor how the sole occupant would play the roles of sensor operator, tactics officer, and pilot. So, they should probably be taken with a pinch of salt, at best it may have been able to deploy sonobouys for other aircraft and ships to listen to. In the end only the two prototype A106s were built. The Italian Navy presumably deciding that if it was going to the trouble of having manned aircraft on its ships they may as well be able to do something useful when there wasn’t an ASW exercise to take part in, like collecting the mail.

It’s the late ‘70s and everyone’s favourite Somerset based aircraft manufacturer is having something approaching success with its Lynx maritime attack helicopter. The next obvious move was to build on that by making a civilian version for the offshore and VIP market. Obvious if you’re not familiar with the Lynx anyway which is an ergonomic and audible nightmare, with average endurance, and a maintenance hours per flying hour problem…

The Westland 30-100 used the same rotors, engines and transmission as the Lynx but mated it with a boxier fuselage which could apparently seat 22. Which would have been a claustrophobic experience if sitting in the back of a 9-passenger configured Lynx is anything to go by. The Westland 30 was also a heavy aircraft with a max take-off weight of almost six tonnes, a figure the Lynx wouldn’t get close to until the Mk8 in the mid-90s. This didn’t do anything for the performance the early Gem engines not being up to hauling around something that heavy.  Consequently, the WG30 was poor in range, power, and operating costs. On the plus side it meant it rarely flew with more than about 10 people in the back which must have made it quite roomy.

In 1985 in an attempt to prove Westlands was a going concern and maybe worth another company, Sikorsky say, investing in the Thatcher government convinced India to purchase 21 WG30s. Using a UK funded grant of £65 million and offers of further aid. Which sounds a lot like bribery. In four years of service the aircraft posted a £5.6 million operating loss, were limited in passenger capacity to ensure safe they met the performance requirements for safe operation, and required engine servicing every 70 hours. After two fatal crashes in 1988 and ’89 the fleet was grounded. Operators in the USA meanwhile seemed no more enamoured of them with issues around the auto-stabilisation system, the levels of maintenance required, and lack lustre customer support. Issues that wouldn’t have surprised any Lynx operator.

The obvious solution to many of the WG30’s woes would be to add more power, however there’s only so much you could usefully put through the four rotor blades. By the time Westlands bit the bullet and produced the bigger better -300 series with a five bladed rotor head, CT7 engines, and modern avionics it was too little too late. [4] Even attempts to sell it to the UK military failed in favour of the Merlin HC3. Ultimately Westlands asked for the type certification to be cancelled ensuring none of the 41 Westland 30-100s that were been built can fly again.

[4] The single built example of this and the -200 are now at the Helicopter Museum in Weston-Super-Mare.

The Mi-6 managed to combine a steam punk aesthetic with being the World’s largest production helicopter, it was a truly glorious machine and the lack of a nose mounted conservatory in its successor the Mi-26 leaves us all the poorer. The Mi-10 on the other hand was a flying crane derivative of the Hook which failed to live up to the glory of its older sister.

Removing the bottom half of the fuselage the resulting gap between the aircraft and the ground was filled with a stalky 3.75m tall 6m wide undercarriage. For reasons to do with helicopter aerodynamics the right-hand legs were 300mm shorter than the left.  Having built possibly the most ridiculous looking landing gear known to man there must have been some disappointment when it was found to shimmy while ground taxing.

It was also discovered that carrying underslung loads was difficult due to the poor view from the cockpit even when using the built in CCTV system.

Realising the requirement to carry a bus or prefab building underneath the fuselage wasn’t the killer feature the USSR needed the later Mi-10K featured a 2m shorter undercarriage and a second aft facing cockpit underneath the first. Because nothing says we got it right first time like giving the pilot somewhere else to sit. This made it much better for carrying underslung loads up to around 11 tonnes in weight. Or about what you could get inside a Mi-6. Which probably explains why only 55 or so Mi-10 were built in total, there only being so many times you need to move something you can’t get in or under a Hook.

As part of a Stalin ‘inspired’ post war rush to revive helicopter development Yakovlev were ‘invited’ to design a heavy lift helicopter. The task seemed simple, make a boxy fuselage to put everything in and put a rotor at each end to lift it off the ground. As with most things helicopter related it turns out nothing is that simple.

Power was to be provided by the same Shvetsov Ash-82V engine, gearbox, and rotors as used in the Mi-4 Hare. Except two of them. Presumably due to issues of sanity one was placed just above the loading ramp and the other was tilted over and squeezed behind the cockpit. To stop the blades from clashing a synchronisation shaft connected the two gearboxes and also allowed power to be transferred front to rear, or vice versa, in the event of an engine failure. Outside of this list, this has not proved a popular configuration.

The first indication that everything may not be right with the Horse came during ground testing when the rear rotor vibrated itself and its gearbox free and committed seppuku ripping the fuselage apart. Further trials revealed that behaving like a tumble dryer with a brick in it was actually a feature of the Yak-24 and that it might be an idea to design it out. Eventually, and possibly in a fit of frustration, the problem was solved by removing half a meter from the end of each rotor. Despite these setbacks command economies wait for no man and the aircraft entered state trials in late 1953 barely a year after the programme had started. During these another prototype was lost but it was the ‘50s so no one seems to have minded although it probably didn’t help with the final development, the complexity of which delayed service entry by two and a half years to 1955.

Despite having a briefly record setting lift capability as few as 40 and at most 100 Horses were produced with vibration and accidents plaguing its career. Still at least Yakovlev could fall back on producing world-beating VSTOL fighters to make ends meet…

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3. Bristol Belvedere ‘Bevel Drive Box’

Form follows function and that’s as true for the Bristol Belvedere as any other helicopter. Unfortunately, the function it followed was that of an anti-submarine warfare helicopter, and despite the Admiralty deciding to go with a licence-built version of the Sikorsky S-58 Bristol didn’t see any reason to radically change their design. So, they didn’t and sold it to the RAF as a transport helicopter instead. To be fair the RAF don’t seem to have thought to ask for any changes either.

This left troops trying to board through a door four feet off the ground as the fuselage was still high enough to allow torpedoes to be loaded on the underside. Which turned out not to be a major requirement in the jungles of Borneo due to the paucity of submarines. Taking a leaf out of Yakovlev’s book Bristol put the engines at either end of the cabin. Going one further they positioned the rear one in the fuselage precluding the use of a loading ramp. Meanwhile the one at the other end blocked access to the cockpit, which was probably a smart move but was ultimately defeated by installing a bulge on the left of the fuselage. To make matters more interesting for the pilot the engines were started with AVPIN a substance which helpfully doesn’t need oxygen to burn and will happily do so if mishandled. This left them with the choice of squeezing back past the on-fire engine compartment or jumping to the ground and breaking an ankle.

Introduced into service in 1961 the Belvedere could carry 19 troops or 6,000lbs of cargo, which sounds moderately impressive. However, that year also saw the Wessex Mk1 join the Royal Navy and with only half the Gazelle engines it could carry 16 troops or 4,000lbs of cargo and was less complicated to maintain. With all its shortfalls it’s something of a surprise that Bristol’s managed to sell any Belvederes, but as a portent of the RAF’s future attitude to helicopters they actually bought 26.

2. Aérospatiale Puma HC1

The Puma HC1 entered service with the RAF in 1971 and inexplicably wasn’t upgraded for 40 years. Which is probably some sort of indication of the high regard rotary wing aviation is held in by the bits of the Air Force that control the money. During that time there were 20 crashes, none of which were attributable to enemy action, killing 31 people. [5]

This somewhat excessive accident rate was at least partly due to the engine controls not featuring anticipators. Fitted in most helicopters these increase the speed of the engine as the pilot raises the collective before the extra drag from increased pitch on the rotors slows their rotation. On its own this wouldn’t be the end of the world however the Turbomeca Turmo engines also took around five seconds to spool up from idle to a speed where they were actually turning the rotors. But why would it be at idle you may ask. Well in certain conditions it’s possible for the aerodynamic forces to drive the rotor system rather than the engines. Typically, when slowing in level flight. If the rotor speed goes above the level for normal flight the engine governor will reduce fuel flow to prevent an overspeed. As this will have no effect the governor will keep reducing fuel flow until it hits the idle stop. In these situations, as the aerodynamic forces drop off there will be nothing driving the Puma’s rotors for several seconds and inertia only gets you so far. On the plus side this gives an opportunity to check all the blades are still there while waiting for normality to resume. Assuming you haven’t hit the ground by then. To be fair to the Turmo it provided sterling service to SNCF powering their trains.

To add insult to injury the early Puma models narrow track undercarriage and high centre of gravity leave the aircraft relatively unstable on the ground.  This has resulted in Puma’s being blown over when the wind unexpectedly changed direction. Which is embarrassing if you’ve left them parked unattended. It also probably explains why the UK have never cleared theirs to operate off ships.

For those wondering Eurocopter did fix these problems fairly early in the production of the Puma with the Makila engine solving all the Turmo’s problems and being a suggested upgrade to the RAF’s for three or four decades before it actually happened in 2012. The Super Puma models having also helpfully moved the main gear further outboard to increase stability on the ground. Although the latest models have introduced a new problem of the rotor head coming off. Which is as fatal as it sounds.

[5] Tip of the hat to UK Serials which has more accessible records of UK military accidents than the UK military. Even if you’re in the UK military.

The Robinson R-22 is about as light and simple as you can make a helicopter. For instance, the rotor brake appears to be connected to the operating handle by an easily broken, if shockingly expensive, sink chain and the whole aircraft is so light it can be wheeled in and out of the hangar by one person. This lightness makes it cheap to operate. Unfortunately, it also makes it extremely attractive for flying schools despite there being much better training aircraft available. [6]

There are two major issues with the R-22, and to some extent its bigger siblings the R-44 and R-66. Firstly, the lightweight main rotor has very little inertia, so if the engine stops there’s only around a second to lower the collective before the rotors are no longer spinning fast enough to sustain auto-rotation. This also makes practice auto-rotation relatively terrifying for the first few hundred goes as the lack of inertia makes the rotor speed race up and down at the slightest movement of the controls.

The second issue is known as mast bumping and is a phenomenon unique to helicopters with two bladed main rotors. As the blades rotate, they flap up and down as the amount of lift generated changes due to the altering airflow and pitch. Generally, up on the side going forward relative to the airframe and down on the retreating side. If there are only two blades as one goes up the other goes down, like a seesaw, and in extreme cases the root of the downward going blade can strike the shaft. [7] This is at least as bad as it sounds and can lead to the blade removing the tail boom, cockpit roof, and the entire rotor head departing the aircraft. This is most likely to happen in low-g situations, such as in turbulence, where the fuselage no longer hanging from the rotor disc will roll right due to the side thrust from the tail rotor. At this point any rational person would apply left cyclic to level the aircraft. Which will cause mast-bumping, rotor separation, and death. In that order.  R-22 training therefore includes a heavy emphasis on avoiding turbulence and if the aircraft rolls right unexpectedly counterintuitively pulling back on the cyclic to increase the g and load up the rotor system. The FAA require a separate logbook signature to state this training has been conducted before you’re even allowed to fly a Robinson product solo while EASA require it as part of the type rating. Despite this there have been multiple accidents which cannot be explained by turbulence or mishandling alone.

To be fair some people say that if you train on something that’s difficult to fly everything else will be easy, presumably these people were also taught calculus before basic addition and learnt to drive in a Formula 1 car. To give an illustration of why that idea is complete bobbins between 1997 and 2010 the R-22 was responsible for 28% of civilian helicopter accidents in the UK, while only making up around 8% of rotary wing aircraft on the G register. [8]

[6] Your author gained his PPL(H) and CPL(H) on an R-22, after already learning to fly helicopters on the Squirrel and 50 hours hands-on time in the Lynx. Which is about the right lead in for the R-22.

[7] This is also known as a teetering head due to the ridiculous American English use of the name teeter-totter for a seesaw.

[8] 104 R22 in the G-INFO database at the time of writing the article against 1208 UK registered civilian helicopters.

Bing Chandler is a former Lynx Observer and CPL(H), who has spent the last eight years working in Air Safety. He also supplies holy vestments for the Church of the Wyvern.

The Hush-Kit Book of Warplanes will feature the finest cuts from Hush-Kit along with exclusive new articles, explosive photography and gorgeous bespoke illustrations. Pre-order The Hush-Kit Book of Warplanes here. Save the Hush-Kit blog. If you’ve enjoyed an article you can donate here. Your donations keep this going. Thank you. Our shop is here and our Twitter account here @Hush_Kit. Sign up for our newsletter here:

I’ll just note that plank drivers are never concerned about the condition of their aircraft’s Jesus nut.

It would be remiss of me not to mention that the first man-made aircraft to fly on another planet were actually the balloon probes deployed by the Soviet Vega landers on Venus in 1986.

Even though it can’t really decide whether it’s a blimp or a helicopter, I think the Piasecki PA-97 would make a fine addition to this list.

Can I nominate the civil Puma, Bristow’s Tiger AS332L ? There was no more a miserable 2 1/2 hours spent than a kidney-busting journey out to the East Shetland basin direct from Aberdeen in the early 1990s with 17 pax jammed in the back, suited up, with your knees intermeshed with the punter opposite you and only able to get one buttock on the tiny seat and all under the deafening whine of the Makilas.

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