N500 Naviplane

The N500 arriving at Dover in 1980
Class overview
Name:	N.500 Naviplane
Builders:	SEDAM/SNCF
Operators:	Seaspeed, Hoverspeed
Preceded by:	N.300 Naviplane
Built:	-1977
In service:	1977 -1985
Completed:	2
Scrapped:	2
General characteristics
Type:	hovercraft
Length:	50 m (160 ft)
Beam:	23 m (75 ft)
Height:	17 m (55 ft 9 in) hovering
Installed power:	5 x 2,535 kW (3,400 hp)
Propulsion:	5 × Avco-Lycoming TF-40 turboshaft
Capacity:	400 passengers 55 cars
Crew:	15

The N500 Naviplane was a French hovercraft built by SEDAM (Société d'Etude et de Développement des Aéroglisseurs Marins) in Pauillac, Gironde for the cross channel route. Intended to have a large passenger and crew capacity, it was for a while the largest hovercraft. Only two were built. The first was destroyed by a fire before entering service, the second proved unreliable and was broken up in 1985 at the end of its service.

The N500 was one of the world's largest hovercraft; it could transport 400 passengers, 55 cars and 5 buses. It was also one of the fastest and reached a speed record for a travel from Boulogne to Dover at an average speed of 74 knots (137 km/h).

The mass of the N500 was 260 tons, it was 50 m long and 23 m wide.

1 pilot. 1 co-pilot. Seated side by side in the cockpit. 1 radar-navigator seated at the rear part of the cockpit.

6 to 8 stewardess.

6 stower-men for the cars.

Flight yokes controlled the horizontal tail wing (elevator), propeller pitch and the thrust power of the 3 propulsion gas turbines

Rudder pedals controlled the two aerial rudders.

Two thrust levers controlled power of the two lifting gas turbines.

Obturation flaps system between the air cushion chamber and the skirts provided additional longitudinal and lateral control.

Later modifications (1983) included:

Data from

General characteristics

Performance

Avionics
The navigator has two marine Decca radars (band S, 2-4 GHz, a 7 cm and 10 cm wavelength), one slave radar for the pilot, two VHF radio.