You are not logged in.


Sunday, May 15th 2011, 10:02pm

Soko Zmaj Twin-Engine Attack Bomber

Technical Description

Mid-wing cantilever monoplane. Wings have constant taper from fuselage to tips with all of the taper on trailing edge. All-metal structure, centre-section with three, outer sections with two spars. Entire trailing edge is hinged, inner portions acting as camber changing flaps and outer sections as ailerons. Slotted type dive brakes hinged under wings outboard of engine nacelles. These brakes lie flush with the under surface of the wings when retracted.

Fuselage is an oval section all-metal monocoque structure stepped up beneath the leading edge of the wings to provide a ventral rear-firing gun position.

Cantilever monoplane type tail unit, with twin fins and rudders. The tailplane has an eighty-degree dihedral and vertical surfaces at the extremities are toed in. All metal structure with metal-covered fixed surfaces and fabric-covered elevators and rudders. Movable surfaces have trimming tabs.

Retractable type undercarriage. Single cantilever shock-absorber legs retract backwards into tail of engine nacelles. Retractable tail wheel.

Bomb-aimer’s position in glazed nose of the fuselage. Pilot and wireless operator/air gunner in tandem under a continuous transparent canopy offset to the port side of the centre-line. Armament consists of one fixed forward firing M40 13.2mm machinegun with 400 rounds of ammunition in the starboard side of the fuselage and two free-firing M40 13.2mm machinegun each with 250 rounds of ammunition – one in the upper and one in the lower gun positions at the after end of the crew accommodation. Internal bomb cell for two 500 kg, three 250 kg or ten 100 kg bombs; external racks for up to eight 50 kg bombs or flares. Alternatively, one aerial torpedo can be carried on external centre-line mount.

Two Pratt and Whitney R-2000C fourteen cylinder radial air cooled engines of 32.8 litre displacement. Power output 1,350 hp at 2,700 rpm.

Span 17.04 metres; Length 13.23 metres; Height 4.5 metres. Wing area 43.8 square metres. Empty weight 5,484 kg; loaded weight 8,693 kg.

Maximum speed 570 kph; cruising speed 480 kph; landing speed 125 kph. Ceiling 9,800 metres. Range 2,600 kilometres.

Design History

The Zmaj twin-engine bomber was conceived by the design team of Mihail Mitrovich, Dragoslav Petrovic and Milos Marjanovic to meet requirements of the Royal Yugoslav Air Force for an aircraft to replace its aging Dornier Do17 medium bombers and its Handley Page Hereford anti-shipping strike aircraft. Work on the project was authorised in November 1938 under the designation Project 221. The design was originally expected to use the Pratt and Whitney R-1830 but the availability of the improved R-2000 led to adoption of the latter.

The prototype aircraft was unveiled in December 1940 and was immediately subjected to intensive testing.


Tuesday, May 17th 2011, 4:24pm

Well, since there's no other comments...

Specs look okay; don't see anything wrong with them. Drawing's pretty good, too, though the nose looks rather bulbous...


Tuesday, May 17th 2011, 4:54pm


Originally posted by Brockpaine
Well, since there's no other comments...

Specs look okay; don't see anything wrong with them. Drawing's pretty good, too, though the nose looks rather bulbous...

Yes; that is something that might be addressed in the future - with a bit more horsepower and a solid nose I think the design would be a very useful anti-shipping strike aircraft operating on the deck.


Wednesday, May 18th 2011, 8:12am

Nice drawing !!! Not a beauty but in my eyes a good aircraft !


Sunday, May 22nd 2011, 5:18am

...this looks familiar but I'd be damned if I can put a finger on it....


Sunday, May 22nd 2011, 11:16am

Do217 tail?
Looks good, the nose is a bit bulbous but its sleek and obviously a capable design for Yugoslavia.


Sunday, May 22nd 2011, 11:40am

I will admit it; the empennage is a mash-up from the Dornier Do217. :)

Future design development will likely address the nose of the aircraft and reduce its bulk.