The unlikely aircraft in the photo is the Fairey Rotodyne. Neither pure airplane nor helicopter, it combined features of both. It could take off and land vertically, like a helicopter, then transition to forward flight like an airplane. Using 1950’s technology it was a pretty ambitious project for the times, and might have actually made it into production if not for a number of mischances.
The link above to the wikipedia entry gives most of the story. Projected to carry 40-48 passengers, with a larger version proposed, it failed to get enough commercial orders to go into actual production. The single prototype shown here is as far as it got.
Although it looks like a helicopter with wings, it’s not. The Rotodyne was more like an autogyro than a helicopter; the blades are not powered by direct drive from an engine connected to the central shaft, and they do not provide forward thrust, just vertical lift. (They are spun up by air directed through ducts in the blades to jet motors at the tips.) The propellors on the wing-mounted engines are what provide forward thrust. This makes the rotor assembly mechanically much simpler than a helicopter — an important consideration in maintenance and overall cost. It also could also fly faster than a helicopter of the times.
The original proposal that inspired it called for essentially what would have been a flying bus, capable of connecting cities without needing a full-size airport with runways. Government funding got the project off the ground, and several proof of concept prototypes were built to explore the design concepts.
To summarize the stumbling blocks it encountered:
- There were problems obtaining engines to power it; finding a partner proved difficult for Fairey.
- The Rotodyne had noise problems. For takeoff, the rotor was spun up by tip-mounted jet engines that produced high levels of noise. Although efforts were underway to make them quieter the program ended before that could be accomplished. The blades could still be used to make vertical landings without the jets — through autorotation — which would also work in the event of engine failure.
- As an entirely new concept, attracting commercial operators without anything to compare it to made it a bit problematic. It also failed to get support from the military, despite obvious possibilities for its use. Along with its troop-carrying capacity, clam shell doors in the back would have made it possible to load and deliver large cargo without needing anything more than an open field to operate out of.
- The British government got caught up in postwar austerity measures and misguided industrial policies. The funding for the project got canceled before it could go far enough to get commercial orders to fund production.
- The British government under Defense Minister Duncan Sandys ‘decided’ there were too many aircraft companies and forced consolidation in the industry. Bankruptcies also took a toll. Sandys believed missiles would make aircraft obsolete, and that shaped government policy.
From the Wikipedia entry, here are a few of the operating specs of the Rotodyne:
General characteristics
- Crew: two
- Capacity: 40-48 passengers
- Length: 58 ft 8 in (17.88 m) of fuselage
- Wingspan: 46 ft 6 in (14.17 m) fixed wings
- Height: 22 ft 2 in (6.76 m) to top of rotor pylon
- Wing area: 475 sq ft (44.1 m2) [47]
- Airfoil: NACA 23015[48]
- Empty weight: 22,000 lb (9,979 kg)
- Gross weight: 33,000 lb (14,969 kg)
- Fuel capacity: 7,500 lb (3,402 kg)
- Powerplant: 2 × Napier Eland N.El.7 turboprops, 2,800 shp (2,100 kW) each [49]
- Powerplant: 4 × rotor tip jet , 1,000 lbf (4.4 kN) thrust each [50]
- Main rotor diameter: 90 ft 0 in (27.43 m)
- Main rotor area: 6,362 sq ft (591.0 m2) Rotor aerofoil: NACA 0015
- Blade tip speed: 720 ft/s (219 m/s)
- Disc loading: 6.14 lb/ft2 (30 kg/m2)
- Propellers: 4-bladed, 13 ft (4.0 m) diameter Rotol propellers
Performance
- Maximum speed: 190.9 mph (307.2 km/h, 165.9 kn) speed record [51]
- Cruise speed: 185 mph (298 km/h, 161 kn)
- Range: 450 mi (720 km, 390 nmi)
- Service ceiling: 13,000 ft (4,000 m)
For comparison, here’s the specs on the CH-47 Chinook helicopter:
General characteristics
- Crew: 3 (pilot, copilot, flight engineer or loadmaster)
- Capacity:
- 33–55 troops or
- 24 stretchers and 3 attendants or
- 24,000 lb (10,886 kg) payload
- Length: 98 ft (30 m) [189]
- Fuselage length: 52 ft (16 m)
- Width: 12 ft 5 in (3.78 m) (fuselage)[189]
- Height: 18 ft 11 in (5.77 m)
- Empty weight: 24,578 lb (11,148 kg)
- Max takeoff weight: 50,000 lb (22,680 kg)
- Powerplant: 2 × Lycoming T55-GA-714Aturboshaft engines, 4,733 shp (3,529 kW) each
- Main rotor diameter: 2 × 60 ft (18 m)
- Main rotor area: 5,600 sq ft (520 m2)
- Blade section: root: Boeing VR-7; tip: Boeing VR-8[190]
Performance
- Maximum speed: 170 kn (196 mph, 315 km/h)
- Cruise speed: 160 kn (184 mph, 296 km/h)
- Range: 400 nmi (460 mi, 740 km)
- Combat range: 200 nmi (230 mi, 370 km)
- Ferry range: 1,216 nmi (1,399 mi, 2,252 km) [191]
- Service ceiling: 20,000 ft (6,100 m)
- Rate of climb: 1,522 ft/min (7.73 m/s)
- Disk loading: 9.5 lb/sq ft (46 kg/m2)
- Power/mass: 0.28 hp/lb (0.46 kW/kg)
Compared with a relatively modern design, albeit one originally dating back to 1957, the Rotodyne actually stacks up rather well against the Chinook. That leads to some speculation: would reviving the Rotodyne make sense? It’s not an idle question.
Modern materials like composites, modern power, modern avionics/control systems, and computer aided design should be able to come up with an updated Rotodyne that would offer superior performance over the original — more payload capacity, higher speeds, faster development time, etc.
A version powered by H2 fuel cells utilizing electric motors would be especially intriguing. Could the tip jets be replaced by tiny electric motors with propellors for take off and landing? The noise problem might become no problem at all.
But, is there a niche where it would work? Just for fun, I asked ChatGPT a question:
Describe niche markets where the VTOL and speed of the Fairey Rotodyne would be useful. (I’ve added comments in italics)
The Fairey Rotodyne was a British compound helicopter that combined features of both helicopters and fixed-wing aircraft. The VTOL (vertical take-off and landing) capability and high speed of the Rotodyne make it well-suited for a number of niche markets, such as:
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Offshore oil and gas: The VTOL capability would allow the Rotodyne to take off and land on offshore platforms, making it well-suited for transporting personnel and equipment to and from these platforms. The same would be true of offshore wind farms.
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Emergency medical services: The high speed of the Rotodyne would allow for rapid transport of critically ill patients to hospitals, potentially saving lives. It would be overkill for most runs, but useful in responding to a mass casualty event or bringing in disaster relief.
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Search and rescue: The VTOL capability would allow the Rotodyne to take off and land in remote or difficult-to-reach areas, making it well-suited for search and rescue operations.
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Military transport: The VTOL capability would allow the Rotodyne to take off and land on small, unimproved landing zones, making it well-suited for military transport operations. Its speed and less mechanical complexity would be a plus as well.
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Urban air mobility: The VTOL capability and high-speed would make the Rotodyne a suitable option for short-haul urban air mobility operations, such as transportation of passengers and cargo in congested urban areas. That’s assuming noise issues, emissions, and operating economics work out.
It is worth noting that the Fairey Rotodyne was never put into production, but its design principles and capabilities are still studied and considered for future VTOL designs .
I can think of some additional places where something like the Rotodyne might make sense. Consider the Philippines, the Malaysian Archipelago, the Hawaiian Islands, the Caribbean. What would effectively be a flying inter-island bus service would change the transport dynamics in those areas, as an alternative to ferries and boats, float planes, and helicopters.
A region lacking a developed road or rail net would be another possible land of opportunity. Parts of Africa, Asia, and South America come to mind, along with Alaska and northern Canada.
People will pay for speed and capacity, and speed creates new opportunities. Somebody somewhere ought to be looking into this.
There’s also the military. The Army needs VTOL aircraft, and is looking beyond helicopters, as the Valor program shows. Would a modern version of the Rotodyne offer enough performance gains and operating efficiencies to become a candidate for a new heavy-lift VTOL aircraft?
What are the odds an old concept like the Rotodyne might be viable today? You never know. Hybrid Air Vehicles is bringing back commercial airships. The Grumman Albatross is looking at a revival in Australia. Heck — there are still DC-3s in commercial service.
IF someone were to offer a modern version of the Rotodyne that A) had operating capabilities and lower operating expenses that nothing else could match, B) could compete in niche markets against alternatives while C) making money for its owners, and/or D) could fill a role nothing else could as effectively (as in military uses), why not?