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Mikoyan-Gurevich I-250

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Warenwolf #1 Posted 13 December 2011 - 01:51 PM

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Mikoyan-Gurevich I-250


Performance (of the first prototype)

	Maximum speed:	820 km/h (510 mph; 440 kn)
	Range:			790 km (491 mi; 427 nmi)
	Service ceiling:  11,900 m (39,042 ft)
	Time to altitude: 5,000 m (16,400 ft) in 3.9 min (with VRDK)
	Wing loading:	 245 kg/m² (50 lb/sq ft)


	Guns: 3 × 20 mm Berezin B-20 cannons (160 rounds each)

When the Soviet learned of jet powered fighters like Me-262, they initiated several crash programs to develop a fighter capable of meeting such aircraft on relatively equal terms.
On of the results was the I-250, an aircraft that at first glance pretty much looked like any conventional aircraft, except for the fact that the cockpit was placed far back.  


Due to the lack of a mature jet engine program in Soviet Union at that time, Mikoyan-Gurevich design bureau opted for a so-called mixed-power solution, using the VRDK motorjet powered by the Klimov VK-107R piston-engine.

A motorjet consists of an ordinary piston engine (Klimov VK-107R in case of I-250) that drives a compressor. The compressed air is then led into a combustion chamber, where fuel is injected and ignited, creating thrust. In essence it is a primitive jet engine.
The motorjet like VRDK did not allow for continues use and could only be used for 10 minutes – hence the need for VK-107R to also drive a propeller (in addition of driving the compressor) like in a conventional piston engined fighter, in order for the I-250 to operate longer than 10 minutes.

The design process was plagued with problems from the very start. The engine powerplant was a huge source of problems  – despite the fact that VRDK has been under development since 1942 and on paper uncomplicated, it was by no means a mature technology as the Mikoyan-Gurevich design bureau thought.

The first flight capable prototype flew on the 4th of April 1945, 13 months after the project's initiation. Four days later, VRDK was tested and it was found that the oil cooler was leaking so the engine had to be repaired. Two more tests followed, both times being judged failures, again mostly due to VRDK engine's defects.
On 3 July the speed of 820 km/h at 6,700 m was achieved – unfortunately this prototype was lost two days later, killing the test pilot, due to G limit of the airframe having been exceeded.

By this time, it was starting to be apparent for everyone that mixed power aircraft were dead end in the fighter aircraft development (as noted above, the VRDK could only operate for 10 minutes).
Still it was thought that it could prove useful as a trainer aircraft for VVS pilots (many of them trained as piston-engine fighter pilots), introducing them to jet fighters and development of I-250 continued (a concurrent mixed-power aircraft program which also never resolved engine troubles, SU-5, was canceled).

It was decided that first aircraft were to be delivered by the end of 1945 (it was to be given designation MiG-13) – however due to problems with engine, the factory assigned the task could not deliver the aircraft.

What followed was a witch hunt – several people were arrested, including the factory director and and his quality control manager who were accused of industrial sabotage.

By the time the I-250 was a "finalized product" in October 1946, two years after the project was initiated, it was clear that the jet fighters, like the MiG-9 and Yak-15, were the future of the soviet air force and the there was no need for a I-250 trainer (role given to Yak-15).  After an attempt to redesign the I-250 as an escort fighter for the Soviet Naval Aviation failed, on 3th April 1948 the I-250 project was finally abandoned.

Official BETA RELEASE DATE (according to ESLAF announcement (disinformation manager) ): 30.02.2012

So no need to ask further.

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