SIAT 311A Regional Jet & SIAT 313


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26 May 2006
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The SIAT-311A was also a project for light airliner aircraft to
replace Douglas DC-3,it had straight high wing,T-tail and powered
by two rear mounted engines.



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Following Hesham's example, I've been exploring Flight's archives. German civil projects in a June 1963 edition caught my eye. Do others have further info on the Siebelwerke SIAT 311?

According to Flight, the SIAT 311A twin-jet, a "straight-wing, 17-seat 18,740lb airliner with [5180 lb st] Lycoming PLF1B-2 turbofans [*] hung on the rear fuselage".

Aeroknow has a magazine listing for the Siebel-SIAT 311, listing it as a 20 pass STOL jet. Air Progress Oct/Nov 63

* According to Jane's, the PLF1 was a geared turbofan based on the "T55-L-5 turboshaft with an added Low-Pressure (LP) turbine and central shaft which, via a speed-reducing gearbox, drove a completely new front fan. Via the more powerful PLF1C-1, the design was refined into the ALF502". This engine seems to have been very popular with German designers at the time, also showing up on the early VFW-614.


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From Flug-Revue, June 1963, page 24-27:
SIAT 311 A
* Crew: Two
* Capacity: up to 20 seats
* Length: 17.00 m
* Wingspan: 15.00m
* Height: 4.92 m
* Wing area: 30.14 m²
* Empty weight: 4200 kg
* Max takeoff weight: 8500 kg
* Powerplant: 2× ?, together 2300 kp
* Cruise speed: 710 km/h
* Max. speed: 760 km/h
* Range: 2,000 km
* Service ceiling: 11,000 m
* Rate of climb: unknown
Only 300m to take of, 280m to land.
As this theme came up again, I looked my files, finding in FlugWelt 2/1963, what could be an interesting
detail about the Siebel 311 A:
Designed as an aircraft with unprecedented STOL performance, control problems in the slow speed regime
were foreseen and should be solved by the use of puffer jets in the wing tips and bleed air slots just behind
the trailing edge. A programmable flight control system should handle the mixture of aerodynamic control
and puffer jets.l
Was it lack of funding or the MBB takeover of SIAT that killed it, I wonder?
To my opinion the first due to the latter ;) : After the merger, funds for
"old" Siebel projects probably were hard to raise, especially as there still
were a lot of projects in a similar class of Messerschmitt origin in the archives.
A little bit later, MBB got involved in the production of the VFW Fokker 614
and, besides the problems due to the ambivalent attitude by Fokker, the
protracted history of a design basically simpler, than the SIAT 311A show,
that it quite probably wouldn't have been commercially succesful either.
Some more info
In 1964, Dassault-Breguet planned to construct a civil transport aircraft larger than the Mystère 20, equipped with Rolls-Royce or General Electric CF 700s, and able to transport 32 to 40 passengers over a distance of 1,000 km.

On March 25, 1964, an industrial agreement was signed with the German Siebelwerke-ATG Gmbh Corporation, which would participate in 35% of the manufacture of the aircraft and could bring in other German corporations. [...]
Though orders had been taken at the 1973 Paris Air Show, the program was abandoned in 1975, as much due to the oil crisis as to the financial circumstances of the companies involved.
FLIGHT International, 16 April I964
Attached picture published in the German magazine Flug-Revue Summer 1964


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From Flugzeug Classic 10/2003,

here is the SIAT-311A aircraft and some details of the design.


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Wow Jemiba,

Puffer jets for control at low airspeeds!
This project was definitely aimed at the STOL edge of the envelope.
The un-swept wing planform reminds us early Cessna Citations which overlap the cruise speeds of light turboprops. Other bizjet pilots joke that early Citations are so slow that they need tail-warning radar for traffic avoidance.

As part of a research assignment for a short-takeoff ground attack aircraft (Project SIAT 313).
studied the possibility of turbofan engines with high by-pass ratio air for blowing out at to
branch off wings.

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