IS-4 Jastrząb

The IS-4 was built for aerobatics with a high structural strength and a very high maximum speed which could not be achieved in a vertical dive. Due to the pilot's sitting position and the arrangements of the controls, it was difficult for pilots to exceed the 8g loading limit. During high speed flight it was possible for the air-brakes to be sucked out violently, so most pilots ensured that they remained closed by holding the airbrake control.

• IS-4 Jastrząb – two prototypes built in 1949.
• IS-4 Jastrząb bis – Thirty-five production aircraft, three of which were exported.

{{Aircraft specs

|ref=The World's Sailplanes:Die Segelflugzeuge der Welt:Les Planeurs du Monde Volume II{{cite book|last=Shenstone|first=B.S.|title=The World's Sailplanes:Die Segelflugzeuge der Welt:Les Planeurs du Monde Volume II|year=1963|publisher=Organisation Scientifique et Technique Internationale du Vol a Voile (OSTIV) and Schweizer Aero-Revue|location=Zurich|pages=172–173|edition=1st|author2=K.G. Wilkinson|language=en, fr, de}}

|prime units?=met

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|crew=1

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|length m=6.25

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|span m=12

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|height m=1.3

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|wing area sqm=12

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|aspect ratio=12

|airfoil=Root – NACA 2418, Tip – NACA 2412, Mid – NACA 0012

|empty weight kg=240

|empty weight lb=

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|gross weight kg=357

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|stall speed kmh=67

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|never exceed speed kmh=450

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• Rough air speed max: {{convert|200|km/h|mph kn|abbr=on}}
• Aerotow speed: {{convert|200|km/h|mph kn|abbr=on}}
• Winch launch speed: {{convert|150|km/h|mph kn|abbr=on}}

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|g limits=+7 -4 at {{convert|200|km/h|mph kn|abbr=on}}

|roll rate=

|glide ratio= 20.2 at {{convert|87|km/h|mph kn|abbr=on}}

|climb rate ms=

|climb rate ftmin=

|climb rate note=

|time to altitude=

|sink rate ms=1.04

|sink rate ftmin=

|sink rate note= at {{convert|70|km/h|mph kn|abbr=on}}

|lift to drag=

|wing loading kg/m2=29.7

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{{aircontent

|see also=

|related=

|similar aircraft=

• Vogt Lo 100

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{{reflist}}

{{refbegin}}

• {{cite web| last=Piechowski|first=Piotr|title=IS-4 Jastrząb| url=http://www.piotrp.de/SZYBOWCE/pis4.htm|publisher=Piotr & Renate Piechowski| access-date=19 April 2013}}
• {{cite book|last=Shenstone|first=B.S.|title=The World's Sailplanes:Die Segelflugzeuge der Welt:Les Planeurs du Monde Volume II|year=1963|publisher=Organisation Scientifique et Technique Internationale du Vol a Voile (OSTIV) and Schweizer Aero-Revue|location=Zurich|pages=172–173|edition=1st|author2=K.G. Wilkinson|language=en, fr, de}}

{{refend}}

• Taylor, J. H. (ed) (1989) Jane's Encyclopedia of Aviation. Studio Editions: London. p. 29

{{commons category|IS-4 Jastrząb}}

• http://www.piotrp.de/SZYBOWCE/pis4.htm
• https://web.archive.org/web/20100501051452/http://kionastore.com/plan-1530.html
• http://www.vintagesailplanes.de/szd__4.htm

{{Polish gliders}}

{{DEFAULTSORT:IS-4 Jastrzab}}

Category:1940s Polish sailplanes

Category:Aircraft first flown in 1949