Engines – Power

Beta Technologies Alia

TerryLeave a comment
Alia-250

The Alia-250 was inspired by an Arctic tern and features a 50-foot (15-m) wingspan and an in-house-built electric propulsion system powered by high-density lithium batteries. Beta estimates a 250-mile (402-km) range and top speed of 138 mph (222 km/h).

In 2021 Beta Technologies received the very first military airworthiness approval for manned electric aircraft flight, meaning the Air Force was confident enough to put its own pilot in the seat and take flight. A few months ago, Beta delivered the Alia platform (in conventional takeoff and landing/CTOL form) to the US Air Force at Florida’s Eglin Air Force Base.

Beta completed a full transition from VTOL hover to wing-borne cruise, and then back to hovering for landing, becoming the first company ever to demonstrate that feat with a pilot on board. Beta test pilot Nate Moyer took the helm at New York’s Plattsburgh International Airport, guiding the Alia-250 straight upward off the ground via its four horizontal electric propellers in April 2024.

Once it was high enough, the rear propeller kicked in, and as the aircraft gained enough speed for the wing to take over, the wing-top propellers slowed to a stop for a short cruise flight. Shortly thereafter, it turned around, the four propellers flipped back on, and it glided down toward the airstrip before coming to a mid-air halt and gently dropping straight down for the landing.

Alia-250

This ALIA CX300 electric conventional take-off and landing aircraft has kicked off Norway’s Test Arena for Zero & Low Emission Aviation after completing a weeks-long tour of major European countries in 2025.

ALIA CX300

In 2025 BETA Technologies has delivered its ALIA CX300 electric CTOL to the company’s first customer. The short-hop passenger aircraft will now be used to evaluate use cases and possible routes for zero-emission operation in the Nordic region.

Unlike its electric vertical take-off and landing counterpart – the A250 – the ALIA CX300 gets in the air and lands using a runway. It’s designed to carry five passengers plus a pilot over short distances between airports, and features an electric motor driving a single five-blade prop to its rear. According to the spec sheet, its onboard batteries should be good for more than 300 nautical miles between one-hour top-ups.

ALIA CX300

The aircraft’s very first passenger pioneers were flown from Long Island to the John F. Kennedy International Airport, staying in the air for 45 minutes. Now the first ALIA CX300 has been delivered to Bristow Norway AS, a subsidiary of US helicopter operator, the Bristow Group.

The delivery to Stavanger Airport in Western Norway’s Rogaland county also marks the end of a weeks-long 6.976-km (4,335 mile) demonstration tour of seven EU countries by the aircraft, which began in Ireland and closed in Norway. It also signals the start of operations for Norway’s Test Arena for Zero & Low Emission Aviation.

The first test flight by a BETA-trained Bristow pilot was also undertaken at the launch event, following on-site instruction at BETA’s Vermont headquarters recently. Bristow pilots and aircraft maintenance personnel will now undertake further demonstration flights over the next six months, in cooperation with Avinor and the Civil Aviation Authority of Norway, as part of a “six-month regulatory sandbox evaluation project.”

BETA ALIA CX300

The battery-electric aircraft, manufactured by BETA, seats two crew and up to 5.6 cubic metres of cargo on missions for up to approximately 398km.

The ALIA CX300 first took off in New Zealand on 17 October 2025, flying in New Zealand from Tauranga to Hamilton after a sunrise blessing ceremony.

Alon X-A4 Aircoupe

TerryLeave a comment
Alon A-4 N6399X

The 1966 X-A4 Aircoupe was a prototypical four seat development of the A2.

One was built, N6399X, first flying on 25 February 1966. Priced at $11,000, it did not enter production.
Engine: 150hp Lycoming O-320A
Wingspan: 30’0″
Length: 20’9″
Useful load: 1107 lb
Max speed: 150 mph
Cruise: 140 mph
Stall: 52 mph
Range: 755 mi
Seats: 4

Allison-White 1916 Biplane

TerryLeave a comment

Designed by Karl White, designer of the Curtiss-Wright Junior, the Allison-White 1916 Biplane single-place had an open-framework fuselage.

After Allison dropped out of the project, White went on to build and fly the plane, which crashed on its first take-off, and was so badly damaged as to be abandoned where it fell.

Engine: 50hp Gnôme
Wingspan: 36’0″
Seats: 1

Air Capital Watkins SL-1

TerryLeave a comment
Watkins SL-1 NX470E

Designed by W C “Chet” Cummings, the Air Capital Watkins SL-1 NX470E was reportedly built as a marketing test project, priced at $2,750.

Watkins SL-1 NX470E

The title implies more of a funding organization than a factory, and is in all likelihood Watkins Skylark.

Engine: 60hp LeBlond 5D
Wingspan: 37’0″
Length: 23’6″
Seats: 2
Useful load: 480 lb
Cruise: 75 mph (with 30hp motor)
Stall: 35 mph

Napier Naiad

TerryLeave a comment

Following on from the light prototype ‘Nymph‘ engine Napier’s first (and late) entry into the aero gas turbine field was in 1947 with their first major type, the E128 ‘Naiad I’ turbo-prop engine.

A contract for a 1,500 shp propeller turbine was given by the Ministry of Air to D Napier & Son in 1945 probably as a replacement for the known future loss of ‘Sabre‘ development work. This became the E128 ‘Naiad’ engine from an October 1945 design. It was built and tested before the Napier Nomad compound aero engine in 1949. Its small axial compressor was based on an existing Nomad type with 12 stages giving 5.5:1 pressure ratio running at 18,250 rpm during take off. At the hot end it had a two-stage turbine providing the power within its slim 28″ maximum diameter. By the end of 1948 it was giving 1,590 ehp in bench tests at Acton and in the Coronation Road Test Tunnels which included 240 lb jet thrust at the take-off rating. The Naiad I gave 1,050 ehp when cruising with turbines at 17,000 rpm.

The Napier Luton Flight Development Establishment installed a Napier Naiad to fly in the nose of an Avro Lincoln which it did on reduced power at the SBAC Farnborough show whilst a mock-up of it in a Vickers airliner nacelle was exhibited on the DNS stand.

A pair of Naiads were coupled together through a double gearbox to reduce drive speed down to a single propellor shaft forming a most compact 3,000 shp engine which was the E128D engine proposed for the Fairey Gannet anti-submarine aircraft. This contract went to Armstrong-Siddley with their ‘Double Mamba’ engine leaving Napier with only castings for airflow tests at Luton.

September 1948

Far more damaging than this was the loss of the turbo-prop engine contract for the Vickers Viscount airliner to the lower powered and 25% heavier Rolls-Royce Dart engine. Vickers did not trust the Naiad’s state-of-the-art axial compressor however their decision provided Rolls with a long term order to power over 400 Viscounts. This blow to Napiers was to have a permanent adverse effect on the Company’s aero gas turbine prospects in the UK.

Type: Turboprop
Length: 102 in (2,600 mm)
Diameter: 28 in (710 mm)
Dry weight: 1,095 lb (497 kg)
Compressor: 12-stage axial
Combustors: 5 chambers
Turbine: 2-stage (18,250 rpm)
Maximum power output: 1,500 shp (1,100 kW) plus 241 lbf (1.07 kN) residual thrust
Overall pressure ratio: 5.5:1
Air mass flow: 17.2 lb/s (7.8 kg/s)
Fuel consumption: 96.2 US gal/h (364 L/h; 101.2 L/ks)
Thrust-to-weight ratio: 1.37 shp/lb (2.25 kW/kg)

Vickers 618 Viking / Nene-Viking

TerryLeave a comment

The Ministry of Aircraft Production Air Ministry Specification 17/44 from Vickers-Armstrongs Limited. The specification was for a peacetime requirement for an interim short-medium haul passenger aircraft. To speed development the aircraft used the wing and undercarriage design from the Wellington but the fuselage was new. Although the original contract referred to Wellington Transport Aircraft, on completion, the name Viking was chosen.

Vickers 618 Viking Article

The initial 19 production aircraft (later designated the Viking 1A) carried 21 passengers, they had metal fuselages and – except for the wing inboard of the nacelles – fabric-clad geodetic wings and tail units. Following feedback from customers, the next 14 examples, known as, featured stressed-metal wings and tail units. The next variant, the Viking 1B, was 28 in (71 cm) longer than the Viking 1, carrying 24 passengers with up-rated Bristol Hercules piston engines, achieved a production run of 115.

The 107th airframe on the Weybridge production line was set aside, and the existing nacelles were replaced by completely new jet pods each housing a Rolls-Royce Nene, with the trailing edge of the wing extended at the rear to fair smoothly into the top of the pod. The Vickers main landing gears were of a totally new type, designed only for this aircraft, with four separate short legs each carrying a wheel which retracted to lie on each side of the jet pipe inside the nacelle. Unlike other Vikings the elevators were skinned with metal, and the metal skin on the wings and tailplane was made thicker than normal. There were also changes to the cockpit, fuel system and other items.

Chief test pilot J ‘Mutt’ Summers flew the Type 618 Nene-Viking from Wisley on April 6, 1948. At different times it bore civil registration G-AJPH and Ministry serial VX856.

On 25 July 1948, on the 39th anniversary of Blériot’s crossing of the English Channel, the Type 618 Nene-Viking flew Heathrow–Paris (Villacoublay) in the morning carrying letters to Bleriot’s widow and son (secretary of the FAI), who met it at the airport. The flight of 222 miles (357 km) took only 34 minutes. It then flew back to London in the afternoon. It obtained a maximum speed of 415 mph (668 km/h) at 12,000 ft (3,700 m) and averaged 394 mph (634 km/h). In 1954 it was bought from the Ministry of Supply and underwent the substantial conversion to Hercules 634 piston engines by Eagle Aviation to join their fleet as Lord Dundonald on September 24, 1954.

Engines: 2 x 2268kg Rolls-Royce Nene I turbojets
Wingspan: 27.2 m / 89 ft 3 in
Wing area: 81.93 m2 / 881.89 sq ft
Length: 19.86 m / 65 ft 2 in
Height: 5.94 m / 20 ft 6 in
Empty weight: 9548 kg / 21050 lb
Take-off weight: 15196 kg / 33502 lb
Max. speed: 753 km/h / 468 mph
Cruise speed: 632 km/h / 393 mph
Range: 555 km / 345 miles
Crew: 4

Ast Special / Mercury Air / ‘Shoestring’

TerryLeave a comment

In 1949 Carl & Vincent Ast, Van Nuys CA. built the Ast Special / Mercury Air midget racer ‘Shoestring’, designed by Rodney Kreimendahl. A single-place mid-wing monoplane.

First flown by Bob Downey, it won the 1951 Continental Trophy piloted by John Paul Jones and registered N26C.

It was restored in 1965 by Ray Cote with wing replacement in 1973 as N16V.

Plans were marketed, and several copies are known to have been built.

Engine: 85hp Continental C-85
Wingspan: 19’0″
Length: 17’8″
Max speed: 210 mph
Cruise: 180 mph
Stall: 65 mph

Southern Aircraft Air Boss

TerryLeave a comment

Designed by Glenn Messer, the 1928 Air Boss was a two-place open cockpit biplane. About 12 were built, fitted with various 90-180hp engines.

Those built included; N715K (Wright R-975), N876Y (OXX-6), N883Y (Siemens), N[884Y (Hisso E), and N9410 (OX-5)

Air Boss 90hp
Wingspan: 32’5″
Length: 23’3″
Useful load: 850 lb
Max speed: 110 mph
Cruise: 90 mph
Stall: 30 mph
Range: 700 mi
Seats: 2

Askew M-3

TerryLeave a comment

The Askew M-3 of 1929 was a modified surplus Thomas-Morse Scout, two-place high wing monoplane.

Registered NX526K c/n 2-X, it first flew about 15 June 1929, powered by a 90hp Curtiss OX-5 engine.

The registration was cancelled on 10 July 1930 when CAA inspectors judged its workmanship as “very poor and dangerous.”