On Mark Engineering
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: 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.
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
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 |
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.
| Força Aérea | Em serviço | Anteriormente voado |
|---|---|---|
| Força Aérea da República Democrática do Congo | Sobre o Contra-Invasor Mark B-26K |
Where On Mark Engineering built, who led it, what it achieved
Fábricas
- Van Nuys works · Van Nuys Airport, California
On Mark Engineering, year by year
On Mark Engineering established at Van Nuys
Ring-spar modification; Marketeer named
Pressurised Marksman first flight
Pregnant Guppy first flight at Van Nuys
Six civil Marksmen delivered; two special-purpose aircraft follow
First production B-26K Counter-Invader flies
B-26K redesignated A-26A and deployed to Thailand
Marksman “Blue Goose” flies night supply drops in Laos for Air America
Everything people ask about On Mark Engineering
What was On Mark Engineering?
What was the On Mark Marksman?
What is the B-26K Counter-Invader?
Did On Mark build the Pregnant Guppy?
Around On Mark Engineering
Todos os fatos foram verificados.
- On Mark Engineering (Wikipedia)
- Douglas A-26 Invader (Wikipedia)
- On Mark Marksman (Wikipedia)
- Aero Spacelines Pregnant Guppy (Wikipedia)
Verificado em 03/10/2026.