View source for PWS-21

{{No footnotes|article|date=September 2019}}
{|{{Infobox aircraft begin 
|name =PWS-21
|image =File:PWS-21 bis 02.jpg
|caption =
}}{{Infobox aircraft type 
|type =Passenger aircraft
|manufacturer =[[PWS (aircraft manufacturer)|PWS]]
|designer = 
|first flight =April 1930
|introduced = 
|retired =
|status = prototype
|primary user =Polish civilian aviation ([[LOT Polish Airlines]]) 
|more users = 
|produced =
|number built =1
|unit cost = 
|variants with their own articles = 
}}
|}

The '''PWS-21''' was a Polish passenger aircraft for 4 passengers, built in [[PWS (aircraft manufacturer)|PWS]] factory in 1930, that remained a prototype.

==Development==
The aircraft was developed for a contest for a successor of [[Junkers F-13]] in [[LOT Polish Airlines]]. The first design of 1929, named '''PWS-21''', developed by Stanisław Cywiński and Jarosław Naleszkiewicz, was a braced high-wing plane, but it was not realized because LOT demanded bigger passenger cab.

The next design, named '''PWS-21bis''', was a cantilever high-wing plane, similar to [[Fokker F.VII]]a/1m design. The only prototype (markings SP-AEC) first flew in the spring, probably April 1930 in [[Biała Podlaska]]. Its counterpart was [[Lublin R-XI]].

The plane appeared not successful. It was too heavy, what resulted in poor speed, ceiling and range, and long take off. In 1931 it was evaluated in LOT airlines, but after a test flight it was returned to the factory. However, at that time there was its development, [[PWS-24]] built, sharing the same lightweight wing, which was ordered by LOT.

==Description (PWS-21bis)==

High-wing cantilever [[monoplane]] of mixed construction, with closed cab and single engine. A fuselage made of a steel frame, covered with [[canvas]]. Straight one-piece wooden wing, with elliptical endings, plywood covered, two-spar. Crew of two (pilot and mechanic), in a cabin before the wing, with twin controls. The cabin had a vertical front windshield and doors on both sides. Next and slightly below in a fuselage, under the wing, there was a cabin for 4 passengers, with a door on the left. The cabin had a toilet. The fifth passenger could be taken instead of the mechanic. 9 cylinder [[radial engine]] Skoda [[Wright Whirlwind J-5]] (240&nbsp;hp take-off power, 220&nbsp;hp nominal power) in the fuselage front, fitted with a [[Townend ring]]. Two-blade metal propeller of a fixed pitch. Conventional [[landing gear]], with a rear skid; struts with shock absorbers joined the main gear with wings. Fuel tanks 250 L in central wing section.

==Specifications (PWS-21bis)==
{{Aircraft specs
|ref=''Polish aircraft 1893-1939'' <ref name=cynk>{{cite book |last1=Cynk |first1=Jerzy B |title=Polish aircraft 1893-1939 |year=1971 |publisher=Putnam |isbn=0-370-00085-4 |location=London |pages=[https://archive.org/details/polishaircraft1800cynk/page/440 440-442] |url=https://archive.org/details/polishaircraft1800cynk/page/440 }}</ref>
|prime units?=met
<!--
        General characteristics
-->
|crew=1 (optionally 2)
|capacity=4 pax / {{cvt|683|kg|1}}
|length m=9.65
|length note=
|span m=15
|span note=
|height m=3.2
|height note=
|wing area sqm=31.75
|wing area note=
|aspect ratio=<!-- sailplanes -->
|airfoil=
|empty weight kg=1300
|empty weight note=
|gross weight kg=2000
|gross weight note=
|max takeoff weight kg=
|max takeoff weight note=
|fuel capacity=
|more general=
<!--
        Powerplant
-->
|eng1 number=1
|eng1 name=[[Skoda-Wright Whirlwind J-5]]
|eng1 type=9-cylinder air-cooled radial piston engine
|eng1 hp=220
|eng1 note=

|prop blade number=2
|prop name=AWK Type C fixed-pitch metal propeller
|prop dia m=<!-- propeller aircraft -->
|prop dia note=
<!--
        Performance
-->
|max speed kmh=167
|max speed note=at sea level
::::{{cvt|136|km/h|mph kn}} at {{cvt|1000|m}}
|cruise speed kmh=
|cruise speed note=
|stall speed kmh=93
|stall speed note={{citation needed|date=September 2019}}
|never exceed speed kmh=
|never exceed speed note=
|minimum control speed kmh=
|minimum control speed note=
|range km=
|range note=
|combat range km=
|combat range note=
|ferry range km=
|ferry range note=
|endurance=<!-- if range unknown -->
|ceiling m=1300
|ceiling note=
|climb rate ms=1.3
|climb rate note={{citation needed|date=September 2019}}
|time to altitude=
|wing loading kg/m2=63.2
|wing loading note=
|fuel consumption kg/km=
|power/mass={{cvt|0.5|hp/lb|order=flip}}
|more performance=
}}

==See also==
{{aircontent|
|related=
*[[PWS-24]]
|similar aircraft=<!-- similar or comparable aircraft -->
*[[Fokker F.VII]]a/1m
*[[Lublin R-XI]]
|lists=<!-- related lists -->
|see also=<!-- other relevant information -->
}}

==References==
{{reflist}}

==Further reading==
*Andrzej Glass: "Polskie konstrukcje lotnicze 1893-1939" (''Polish aviation constructions 1893-1939''), WKiŁ, Warsaw 1977 (Polish language, no ISBN)

==External links==
{{commons category|PWS-21}}
*[http://www.airwar.ru/enc/cw1/pws21bis.html Photos and drawings at Ugolok Neba site] {{in lang|ru}}

{{PWS aircraft}}

[[Category:1930s Polish airliners]]
[[Category:PWS aircraft]]
[[Category:Single-engined tractor aircraft]]
[[Category:High-wing aircraft]]
[[Category:Aircraft first flown in 1930]]
[[Category:Aircraft with fixed conventional landing gear]]