Pashinin I-21
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| {{Infobox Aircraft Begin
|name =I-21 |image = Paschinin I-21.svg |caption = }}{{Infobox Aircraft Type |type =Fighter |manufacturer =Pashinin OKB |designer =Mikhail M. Pashinin |first flight =18 May 1940 |introduced = |retired = |status =Cancelled |primary user = |more users = |produced =1940-1941 |number built =3 |unit cost = |developed from = |variants with their own articles = }} |
The Pashinin I-21 (not to be confused with the Ilyushin TsKB-32, also known as "I-21") was an early 1940s Soviet fighter prototype. Designed by Mikhail M. Pashinin, the I-21 was built to incorporate lessons learned from the combat experiences of Soviet pilots during the Spanish Civil War and the Nomonhan Incident with the Empire of Japan. Despite showing promising performance, the I-21 did not get past the prototype stage, as it was felt the type did not offer a significant enough increase in capability over competitors already in production, such as the Yakovlev Yak-1 or Mikoyan Gurevich MiG-3.
Development
Mikhail Pashinin began development of his monoplane fighter in early 1939. A former employee of N. N. Polikarpov, Pashinin envisioned the I-21 as a replacement for the increasingly obsolescent I-16 in Soviet service. The resulting I-21 featured a low set wing with retractable undercarriage, a Klimov M-107 engine, and a framed canopy with good visibility. The I-21 was of mixed construction, as was typical of many contemporary designs, and had a monocoque rear fuselage made of wood, whereas the forward fuselage was built from welded steel tubing for increased rigidity. Wings were of metal with plywood covering.{{cite book |last=Green |first=William |title=The Complete Book of Fighters |year=1994 |publisher=Salamander |location=London |isbn=1-85833-777-1 |last2=Swanborough |first2=Gordon |page=464}}
The cockpit was placed well aft, behind the wing, and the pilot was seated under a swinging canopy. The I-21's armament consisted of an engine mounted 20 millimeter ShVAK automatic cannon and two 7.62 millimeter ShKAS machine guns, one in each wing. This armament was typical of other Soviet fighters of the period such as the Yak-1. The 20mm ShVAK was later replaced by a harder-hitting 23mm BT-23 cannon. (This gun developed by Jacob Taubin (Яков Таубин) and M. Baburin (М.Н. Бабурин) and is also known under the designation MP-6.)
The prototypes were ultimately powered by Klimov M-105P engines, since the M-107 had run into development troubles of its own, and production of the engine was delayed. Flight testing with the 1,050-hp M-105 began with the first flight on 18 May 1940. Official testing by Soviet authorities was conducted from 6 June, in test pilots discovered that the I-21 had stability problems. As a result, Pashinin made modifications to the second prototype, consisting of new outer wing panels with tapered leading and trailing edges to improve stability. Although an improvement, the I-21 still was not performing as expected, despite some promising speeds of over 480 km/h (300-mph) at sea level. The third prototype featured more extensive remodeling of the wings, with clipped wingtips (reducing wingspan by 1.57-m) and sweeping back the leading edges. In addition, the tailplane was also improved. This last prototype also was fitted with a ventral oil cooler
The third prototype displayed improved performance and handling, but officials complained of the I-21's need for an unacceptably long runway and its tricky character on landing. In the event, a planned pre-series run for five aircraft was canceled by Soviet officials, who likely felt the I-21 simply did not offer much more than types already in established production.
Specifications (I-21)
{{Aircraft specs
|ref={{citation needed|date=August 2019}}
|prime units?=met
|crew=1
|length m=8.73
|length note=
|span m=9.4
|span note=
|height m=
|height note=
|wing area sqm=15.46
|wing area note=
|aspect ratio=
|airfoil=
|empty weight kg=
|empty weight note=
|gross weight kg=2670
|gross weight note=
|max takeoff weight kg=
|max takeoff weight note=
|fuel capacity=
|more general=
|eng1 number=1
|eng1 name=Klimov M-105P
|eng1 type=V-12 liquid-cooled piston engine
|eng1 hp=1050
|eng1 note=
|prop blade number=3
|prop name=constant-speed propeller
|prop dia m=
|prop dia note=
|max speed kmh=580
|max speed note=
|cruise speed kmh=
|cruise speed note=
|stall speed kmh=
|stall speed note=
|never exceed speed kmh=
|never exceed speed note=
|range km=760
|range note=
|combat range km=
|combat range note=
|ferry range km=
|ferry range note=
|endurance=
|ceiling m=10600
|ceiling note=
|g limits=
|roll rate=
|climb rate ms=21
|climb rate note=
|time to altitude=
|wing loading kg/m2=173
|wing loading note=
|fuel consumption kg/km=
|power/mass=
|more performance=
|guns= 2 × 7.62×54mmR ShKAS machine guns, in wings, and one 20×99mmR ShVAK cannon or 23 mm BT-23 cannon firing through propeller hub.
}}