On Mark Engineering

On Mark Engineering

On Mark Engineering Company

A Van Nuys rebuild shop turned surplus Second World War Invader bombers into pressurised executive transports, CIA spy-drop aircraft and the B-26K Counter-Invader that hunted trucks on the Ho Chi Minh Trail.

1954Fundada
ExtintoStatus
5Aeronaves registradas
1Forças aéreas que operam seus tipos
Foto: USAF / Wikimedia Commons (Domínio público)
PaísEstados UnidosFundada1954SedeAeroporto de Van Nuys, CalifórniaStatusExtinto
A história

On Mark Engineering: the company and the aircraft that made its name

Second lives for the Invader

In the 1950s America was awash with surplus Douglas A-26 Invaders, fast twin-engined bombers left over from the war. On Mark Engineering, founded in 1954 at Van Nuys Airport in California, saw them as raw material. Its first conversions stripped out military kit, sealed the bomb bays and added windows and soundproofing. Around 1957 it replaced the main spar carry-through with a steel ring spar, freeing the cabin, and sold the result as the On Mark Executive and Marketeer. From 1961 the Marksman added full pressurisation, making the old bomber a fast high-flying business aircraft.

The Blue Goose and the CIA

Only eight Marksmen were built, and the last two were anything but corporate. Fitted with terrain-following radar and a floor hatch for low-level air drops, they went to companies tied to the CIA. In 1967 one, painted blue and nicknamed the Blue Goose, flew night supply drops for Air America in Laos during the Secret War, until it was judged too fast to drop accurately and too much like a strike aircraft. Both were later evaluated by a clandestine USAF squadron and scrapped.

Counter-Invader and the Pregnant Guppy

On Mark’s biggest military job came in the early 1960s, when the USAF chose it to rebuild the Invader for counter-insurgency. It turned a single B-26 into the YB-26K prototype and then converted 40 B-26K Counter-Invaders with new engines, rebuilt wings and tip tanks; the first production aircraft flew on 30 May 1964. Redesignated A-26A for political reasons, they flew from Thailand against traffic on the Ho Chi Minh Trail, and others went to the Congo. On Mark also did conversion work on the Boeing Stratocruiser that became Aero Spacelines’ Pregnant Guppy, first flown at Van Nuys in 1962.

A Van Nuys rebuild shop turned surplus Second World War Invader bombers into pressurised executive transports, CIA spy-drop aircraft and the B-26K Counter-Invader that hunted trucks on the Ho Chi Minh Trail.On Mark Engineering · verified 2026-10-03

À primeira vista

On Mark Engineering in numbers

A empresa

Resumidamente
Founded 1954

  • Aircraft remanufacturing company at Van Nuys Airport, California
  • Specialised in Douglas A-26 Invader conversions
  • Active until the mid-1970s

Produção

Mais conhecido por
B-26K Counter-Invader

  • 40 B-26K Counter-Invaders for the USAF
  • 8 pressurised Marksman executive conversions, 1961–1964
  • Executive and Marketeer unpressurised conversions
  • Conversion work on the Pregnant Guppy prototype

Hoje

Agora
Extinto

  • Marksman and Counter-Invader survivors in museums and storage

Os números

B-26K Counter-Invaders converted
40
Marksman conversions
81961–1964

A aeronave

Every notable On Mark Engineering aircraft

Aeronave Papel Primeiro voo Construído Status Observação
On Mark Executive Executive transport conversion of the A-26 Aposentado
On Mark Marketeer Executive transport conversion of the A-26 Aposentado Unpressurised; developed from the Executive
On Mark Marksman Pressurised executive transport 1961 8 Aposentado Two special-purpose aircraft for CIA-linked operators
Douglas B-26K Counter-Invader (A-26A) Counter-insurgency attack aircraft 1964 40 Aposentado Remanufactured Invaders; used over Laos and in the Congo
Guppy grávida da Aero Spacelines transporte de carga de grandes dimensões 1962 1 Aposentado On Mark carried out conversion work on the Stratocruiser prototype

Quem os pilota?

On Mark Engineering aircraft in the world’s air forces

1 air forces in the Order of Battle fly or flew On Mark Engineering types. Nenhum deles ainda tem um em serviço.


Lugares, pessoas, registros

Where On Mark Engineering built, who led it, what it achieved

Fábricas

  • Van Nuys works · Van Nuys Airport, California

Linha do tempo

On Mark Engineering, year by year

1954

On Mark Engineering established at Van Nuys

1957

Ring-spar modification; Marketeer named

1961

Pressurised Marksman first flight

1962

Pregnant Guppy first flight at Van Nuys

1963

Six civil Marksmen delivered; two special-purpose aircraft follow

1964

First production B-26K Counter-Invader flies

1966

B-26K redesignated A-26A and deployed to Thailand

1967

Marksman “Blue Goose” flies night supply drops in Laos for Air America


Perguntas e Respostas

Everything people ask about On Mark Engineering

What was On Mark Engineering?
A California company, founded in 1954 at Van Nuys, that remanufactured surplus Douglas A-26 Invaders for civil and military customers.
What was the On Mark Marksman?
A pressurised executive conversion of the A-26 Invader; eight were built from 1961, two for CIA-linked operators.
What is the B-26K Counter-Invader?
A counter-insurgency rebuild of the Invader by On Mark; 40 were converted for the USAF and used in Southeast Asia.
Did On Mark build the Pregnant Guppy?
It undertook conversion work on the Boeing 377 prototype for Aero Spacelines, which first flew in 1962.



Fontes e Leitura Complementar

Todos os fatos foram verificados.

Verificado em 03/10/2026.