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GOT: The Bisnovat SK-1 and SK-2

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#1 Romantic Technofreak

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Posted 02 December 2007 - 03:12 AM

I only can say sorry that my time still did not allow to write a bit more GOT topics, but I hope the situation will get better. This time our theme are the Bisnovat SK-1 experimental aircraft and the SK-2 lightweight fighter prototype. The text is from airwar.ru, translation was done as usual using Babelfish, what proved to be a little troublesome for the SK-1, but very smooth for the SK-2. The referred test period is a bit contradictory in both articles (from 1939 in the one about the SK-1, from 1940 in the one about the SK-2). "SK" stands for "Skoristnii Kryilo = High speed wing" (contributor *Bernhard C. F. Klein* on 1000aircraftphotos.com).



SK-1

SK-1 was an experimental high-speed aircraft, developed by designer Matus Ruvimovic Bisnovat. It was designed and built for the flight investigation of it's wing with different profiles and of the dynamic properties of aircraft with the large wing load as well. Obtaining high speeds by the use of a Klimov M-105 engine was achieved by applying of advanced aerodynamics, large load on the wing and a retractable cockpit canopy. The cabin roof was ensconced within the structure of the metallic fuselage, and at take-off and landing it was revealed, then forming a windshield, and the pilot's seat rose up by an hydraulic elevator, so the necessary sight was ensured (I would have liked to see that configuration, but there is no photo to show it, RT).
The following statements about the wing construction were a bit difficult to understand for me. I read the cantilever wing had the thin profile NACA-23014,5 and was done in one piece, without any plug connections (??), and easily to be removed. It was covered by glued fabric.
The wing surface was polished to mirror brightness. In the experimental order a new cooling system was tested: the area of radiator had 0,17 m2, almost half as usual, and water circulated under the pressure 1,1 kg/sm2. Rudders and ailerons had complete mass balancing. Under response of the state-owned TsAGI institute (Central Institute of Aerohydrodynamics) in 1939 tests were done using wheeled landing gear and nonretractable skis as well.


SK-2

In the second half of the Thirties of last century noticeably all countries engaged in the development of aircraft performed studies and practical experiments to increase the speed of aircraft of all kinds. Especially different wing layouts were tested. Lots of streamlined experimental aircraft were built. In the number of such machines, specially built for a study in real flight at high speeds using wings of different profiles, and also the general dynamic properties of aircraft with specifically high wing loads, there was SK. It was developed at the TsAGI institute by a group of specialists headed by chief designer M.R. Bisnovat.

Aircraft SK outwardly noticeably differed from all analogous machines of that time. Its wing was uncommonly small, cockpit "was embedded" and practically it did not come out from the structure of fuselage, which considerably decreased the total drag in flight at high speeds. With the takeoff and landing in order to ensure to pilot's necessary sight, the cabin roof was were revealed, forming a windshield, and the pilot's seat with the aid of a hydraulic system rose upward. Production engine M -105 with a screw of variable pitch in flight VISH-52, was established on the aircraft.

Since the beginning of 1940 test pilot G. Shianov undertook flights with the SK, and during October of the same year also with the fighter derivation SK-2. This differed from SK by the fact that the canopy was of usual type with emergency dropping mechanism, the oil radiator was transferred to the lower nose section of the fuselage, and the air intakes for the engine were located in the wing root.

The vertical tail assembly and chassis was changed somewhat, the installation of three synchronized machine guns was provided - two calibers of 12,7 mm and one caliber of 7,62 mm. The schematic diagram and basis of construction SK and SK-2 in practice did not differ. In the course of of flight tests of SK and SK-2, interesting material about the stability, the controllability and the take-off and landing characteristics of aircraft with the large specific wing load was obtained. SK-2, as it was noted in the report of flight tests, according to its technical flight data satisfied the requirements, compared to the contemporary high-speed fighter.

Construction of aircraft SK-2 and SK was all-metal. Wing, by area of 9,57 m2, thin profile, is executed without joints (??, above I say "plugs", don't know too much about wing construction, RT), and easily to be replaced. Fuselage was of type semi-monocoque with frames and stringers. The bodies of wing and fuselage too are assembled from pressed duralumin profiles. The undecarriage of single-column type was retracted to an inward direction. The retracting system of main undercarriage, tail wheel and flaps (the latter a TsAGI construction themselves) was hydraulic. The steerable tail wheel ensured a good maneuverability on the earth, facilitated take-off and landing. In spite of the rear arrangement of pilot's cab, survey from it, as test pilot noted, was good.

With engine M-105 delivering a power of 1.050 hp and screw VISH-52 the aircraft SK-2 developed maximum speed at the height of 4900 m of 660 km/h, and at the height of 2700 m - 645 km/h. For the climb of 5000 m it needed 4 min. 20 s. Service ceiling - 10300 m. Take-off weight of SK-2 was only 2300 kg. In spite of the large specific wing load (240 kg/m2), SK-2 possessed completely satisfactory take-off and landing characteristics. The length of its take-off did not exceed 350 m, the rollout path was only 500 m. The experience of the development of aircraft SK and SK-2, but especially the result materials of their tests in air, were subsequently taken into account and used for the design of fighters, which together with an increase of engine power had a greater specific wing load.

So long airwar.ru. No word about a possible employment of the SK-2 itself on the frontier!

Pictures #1 to #3 show the SK-1, #4 and #5 the SK-2. #1 and #2 show a very beautiful model from hobbyvista.com. #3 to #5 are from airwar.ru.

Bis-SK_01.jpg

Bis-SK_03.jpg

sk1-1.jpg

sk2-1.jpg

sk2-2.jpg

Regards, RT



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#2 Wuzak

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Posted 02 December 2007 - 05:15 AM

Amazing looking aircraft RT!

About the SK-1, it is nice that the pilot could see for landing, what about the rest of the time?

#3 Romantic Technofreak

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Posted 03 December 2007 - 12:25 AM

Obviously they were not expecting to have obstacles on level flight... but they could have asked Lindbergh for a mirror after he had his "Spirit" reconfigured...;)

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Regards, RT

#4 GregP

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Posted 03 December 2007 - 01:06 AM

Thanks Holger!

Neat-looking aircraft, even if a bit unusual. Though I think it an attractive creation, I am not particularly fond of high-powered aircraft with the pilot sitting far aft with little to no visibility in the landing configuration or during taxi operations. When I say "not particularly fond," I mean that it would be problematic to operate on a crowded airport.

If operated from an Aerodrome, where the aircraft can be headed into the wind all the time, and if the Aerodrome were not crowded, then it would be fine if a bit blind. Today, we use paved airports instead of Aerodromes, we takes off in the direction of the runway regardless of the wind direction, and we have a lot of traffic to watch out for, so the visibility from this particular aircraft would be terrible.

I suspect the aircraft was probably an attempt to look for a speed record since it certainly was not a fighter! In any case, thanls for the information! :)





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