TsybinNM-1

Purpose: To provide full-scale flight data to support the RSR.

Design Bureau: OKB-256, Podberez’ye, Director P V Tsybin.

In autumn 1956 funding was provided for a research aircraft designated NM-1 (Naturnaya Model’, life [like] model). This was to be a sin­gle flight article with an airframe based upon that of the RSR but simplified, with proven en­gines and stressed for lighter weights. It was completed in September 1958. On 1st Octo­ber Amet-Khan Sultan began taxi testing, and he made the first flight on 7th April 1959, with a Yak-25 flying chase. The flight plan called for
take-off at 220km/h, but after a tentative hop Sultan actually took off at 325km/h, and jettisoned the dolly at 40m (131ft) at 400km/h (248mph). The dolly broke on hitting the runway (on later flights it had an automatic parachute). Sultan easily corrected a slight rolling motion, and flew a circuit at 1,500m at 500km/h before making a landing at 275km/h (90km/h faster than planned). Altogether Sultan and Radii Zakharov made 32 flights, establishing generally excellent flying quali­ties (take-off, approach and landing ‘easier than MiG or Su aircraft’) but confirming neu­tral or negative stability in roll.

The five-spar 2.5-per-cent wing had con­stant-chord ailerons and flaps which were unlike those of the RSR. On the tips were two Mikulin (Tumanskii) AM-5 turbojets each rated at 2,000kg (4,409 Ib) thrust, in simple na­celles without inlet centrebodies. The pilot sat in an ejection-seat under a very small canopy; the low-drag RS-4/01 canopy, resem­bling that of the RSR, was never fitted. Along the centreline were a sprung skid, hydrauli­cally retracted into a long box, and a small tailwheel, while hydraulically extended skids were hinged under the nacelles. For take-offs a jettisonable two-wheel dolly was attached under the main skid. A door under the point­ed tailcone released the braking parachute. After the taxi tests, following recommenda­tions from CAHI (TsAGI) small extra wing sur­faces were added outboard of the engines. The fuselage contained two kerosene tanks, a hydraulic-fluid tank and a nose water tank to adjust centre of grravity to 25.5 per cent of mean aerodynamic chord.

The NM-1 showed that the basic RSR con­cept was satisfactory.