M.Hardy. Gliders & Sailplanes of the world

ICA-Brasov IS-28M

  Two motor glider versions of the IS-28B2 were developed, the IS-28M1 tandem two-seater with a monowheel undercarriage, and the IS-28M2 seating two side-by-side and with a conventional retractable undercarriage; both of these ДальшеMore>>> differed from the B2 chiefly in having the wings moved to the low-set position, and the forward fuselage, cockpit canopies and main landing gear redesigned. The rear fuselage, tail unit and main wing structure were virtually unchanged from those of the IS-28B2; in both versions the wings can be folded from a point just inboard of the ailerons. The IS-28M2 was the first to take to the air, the prototype, registered YR1013, making its first flight on 26 June 1976 and making its public debut at that year's Farnborough air show; the first 10 M2s were allocated to the UK, where they are distributed by Morisonics Ltd, and this version has also been exported to Canada and the USA. The M2 has two main wheels retracting backwards into the wing roots to lie semi-exposed in the centre-section, and incorporating shock-absorbers and brakes; there is also a steerable tailwheel. Wing span is 17m (55ft 9 1/4 in) instead of the 18m (59ft 0 3/4 in) of the IS-28M1, which has a slightly greater length and less height. The latter's undercarriage consists of a retractable monowheel with balloon tyre and outrigger wheels mounted under each wing tip, plus a steerable tailwheel. Deliveries of the M1 were due to begin in 1979, and both versions are powered by a 68hp Limbach SL 1700E1 'flat four' engine, driving a Hoffman HOV-62R two-blade variable-pitch and fully-feathering propeller; there is a single fuel tank aft of the cockpit holding 7.9 Imp gallons.
  Both versions, like the IS-28B2, are of mainly metal construction, the single-spar wings having 2° dihedral and 2° 30' forward sweep at the quarter chord line. The wing, ribs and skin are of aluminium, the metal ailerons are fabric-covered and the trailing edge split flaps, which can be set to a negative position, are now an optional feature, instead of standard as on the B2; there are all-metal two-section Mutter air brakes in the upper surfaces. Wing folding is also optional, the outer panels folding inwards. The fuselage is built in three parts; a metal front portion, built up on two longerons and cross-frames and with glassfibre fairings and engine cowling panels; a centre portion which is an aluminium alloy monocoque; and a rear portion made up of aluminium alloy frames and skin. Like the B2, the cantilever T-tail is of aluminium alloy with slight dihedral on the tailplane; the rudder and the elevator trailing edges are fabric-covered, and there is a trim tab in each elevator. Both versions have full dual controls and a rearward-sliding main portion of the canopy.
  The IS-29DM and IS-29EM currently under development are motorised versions of the IS-29D2 and IS-29E3 respectively.


Data: IS-28M2
Span : 55 ft 9 1/4 in
Length: 24 ft 7 1/4 in
Height: 7 ft 0 3/4 in
Wing area: 196.3 sqft
Aspect ratio: 15.8
Empty weight: 1,168 lb
Max weight: 1,642 lb
Max level speed: 124 mph
Economical cruising speed: 102.5 mph
Min sinking speed: 2.85 ft/sec at 50 mph
Best glide ratio: 29:1 at 62 mph
Take-off run: 525 ft
Range with max fuel: 280 miles