OSGA-25 hydroplane catamaran

[Arjen]

A design by Vladimir Gartvig, drawing by Vladimir Meshcherin.
Images OSGA-25 1-4 from Russisches Design - Tradition und Experiment 1920-1990 by Alexander Lavrentiev and Yuri Nasarow, Ernst & Sohn 1995.
Images OSGA-25 5-7 found here:

Gashetka | Transportation Design

Transportation design, industrial design, engineering, aircraft and space industry, etc. Yury.

gashetka.tumblr.com

View: https://www.youtube.com/watch?v=UTnw_7UvRdo

Text from youtube-page:

Rare (there was only one) OSGA-25 'Express' Soviet high speed catamaran passenger. The first publication of a catamaran in 1934, final testing in October 1939. April 17, 1940, was used to transport passengers between the cities of Sochi and Sukhumi. Max speed (without passengers) : 51.84 Knots Max speed (the load) : 46.44 Knots Cruising speed : 37.8 Knots Material hull textolite and steel mesh in several layers Full load displacement : 42 t Main power system (ex aviation engines) : 2 X 1050 hp Secondary power system (car engines) : 2 Х 50 hp a seating capacity : 100-150 passengers p.s. When the war (between the Soviet Union and Germany in 1941) engines have been dismantled for the Soviet torpedo boats and to avoid capture of the ship was destroyed.

Ukrainian site with more images and information:

Глиссер-катамаран ОСГА-25 "Экспресс"(СССР)+видео

Мало кто знает, что в Сочи в период 1939–1941 гг. проходил испытания и выполнял рейсы по маршруту Сочи – Сухуми единственный в мире пассажирский 150-местный глиссирующий катамаран. Быстроходное судно поражало своим внешним видом и своими возможностями. Гладкие обтекаемые самолётные аэродинамичес

udachnyj-enot.com.ua

 

[ILikeTanks]

Is that a surface-effects ship built pre-ww2?

 

[TomS]

Is that a surface-effects ship built pre-ww2?

No, just a planing hull catamaran. There's no cushion or lift engine.

 

[publiusr]

Torpedoes carried in between hulls?

 

[TomS]

Torpedoes carried in between hulls?

It was a high-speed passenger ferry, not a warship. Look at the arrangements drawing (Image 2) and you can see the passenger seating in the hulls and what looks to be a lounge or restaurant in the center structure.

 

[Dilandu]

Torpedoes carried in between hulls?

It's a passenger ship, not torpedo boat.

 

[publiusr]

It wouldn’t be a bad design for a PT.

 

[ILikeTanks]

No, just a planing hull catamaran. There's no cushion or lift engine.

However the shape of the ship unmistakenly create an air cushion and lift force, because it is in the general shape of an airfoil and even tilted, which would be raising the lift coefficient even higher. Even if the designers didn't intend this (which is unlikely considering how the ship looks like an airfoil with some AoA), the shape would create some lift anyways. Lift is made due to shape, not due to what was originally considered in a design. The Hydrodrome HD-4 was reported to generate some aerodynamic lift, and due to proximity with ground, necessairly also an air cushion, due to how the boat's sponsons are shaped like wing

 

[ILikeTanks]

Anyways, there are plenty of SES that do not have powered cushion, however they lift up due to their velocity.

 

[southwestforests]

Interesting boat. Too bad that the turns of history took away its future.

 

[TomS]

Anyways, there are plenty of SES that do not have powered cushion, however they lift up due to their velocity.

There are some air-entrained catamarans, but I would not call those SES. Surface-effect ships more or less by definition use an enclosed air cushion with powered lift.

In this case, they certainly have looked to streamline the shape for reduced drag (seen on quite a few other period fast vessels). It's possible that there is some lift from the center section, though the tall and wide superstructure on top rather spoils the effect. But I would expect that the stepped planing hulls will provide a very large majority of the uplift.

 

[ILikeTanks]

There are some air-entrained catamarans, but I would not call those SES. Surface-effect ships more or less by definition use an enclosed air cushion with powered lift.

In this case, they certainly have looked to streamline the shape for reduced drag (seen on quite a few other period fast vessels). It's possible that there is some lift from the center section, though the tall and wide superstructure on top rather spoils the effect. But I would expect that the stepped planing hulls will provide a very large majority of the uplift.

This image showed earlier clearly shows an airfoil-like shape, which means it is an airfoil, or works as one. It also showed great aeslestic design and styling resciminent of artwork from the era though.