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⚫
{{Infobox weapon
{{Refimprove|date=October 2013}}
⚫
| name = R4M rocket
⚫
{{Infobox Weapon
| image = File:R4M.jpg
⚫
|name=R4M rocket
| image_size = 300
|image=[[File:R4M AT version.jpg|300px]]
|caption=The anti-tank version of the R4M rocket known as the [[Panzerblitz_(missile)|Panzerblitz]] on display at the [[Steven F. Udvar-Hazy Center]]
| caption = R4M "Orkan" on display at the [[German Museum of Technology]]
|origin=[[Germany]]
| origin = Germany
|type=[[Rocket]]
| type = [[Rocket]]
<!-- Type selection -->
<!-- Type selection -->
|is_ranged=yes
| is_ranged = yes
|is_bladed=
| is_bladed =
|is_explosive=yes
| is_explosive = yes
|is_artillery=
| is_artillery =
|is_vehicle=
| is_vehicle =
|is_UK=
| is_UK =
<!-- Service history -->
<!-- Service history -->
|service=1944-1945
| service = 1944-1945
|used_by=[[Luftwaffe]]
| used_by = [[Luftwaffe]]
|wars=[[World War II]]
| wars = [[World War II]]
<!-- Production history -->
<!-- Production history -->
|designer=
| designer =
|design_date=1944
| design_date = 1944
|manufacturer=[[Heber AG]], [[Osterode am Harz|Osterode]], [[Germany]]
| manufacturer = [[Heber AG]], [[Osterode am Harz|Osterode]], Germany
|production_date=
| production_date =
|number=
| number =
|variants= Air-to-air & Air-to-ground
| variants = R4M ([[Air-to-air rocket|air-to-air]])<ref name="ABC" /><br>R4HL ([[Air-to-ground rocket|air-to-ground]])<ref name="ABC" />
<!-- General specifications -->
<!-- General specifications -->
| weight = {{convert|3.85|kg|lb|abbr=on|sigfig=3}}<ref name="ABC" />
|weight=3.85&nbsp;kg
| length = {{convert|812|mm|in|abbr=on|sigfig=3}}<ref name="ABC" />
|length=812&nbsp;mm
|part_length=
| part_length =
| width = {{convert|55|mm|in|abbr=on|sigfig=3}}<ref name="ABC" />
|width= 55&nbsp;mm
|height=
| height =
|crew=
| crew =
<!-- Ranged weapon specifications -->
<!-- Ranged weapon specifications -->
|cartridge=
| cartridge =
|caliber=
| caliber =
|action=
| action =
|rate=
| rate =
|velocity=525&nbsp;m/s (1,175 mph)
| velocity = {{convert|525|m/s|ft/s|abbr=on|sigfig=3}}<ref name="ABC" />
| range = {{convert|600-1000|m|yd|abbr=on|sigfig=3}}
|range= 600-1,000&nbsp;m
| max_range = {{convert|1500|m|yd|abbr=on|sigfig=3}}<ref name="ABC" />
|max_range= 1,500&nbsp;m
|feed=
| feed =
|sights=
| sights =
<!-- Explosive specifications -->
<!-- Explosive specifications -->
|diameter=
| diameter =
| filling = HTA 41{{efn|name=HTA|HTA 41 composition: 40% [[Hexogen]] ([[RDX]]), 45% [[TNT]] and 15% [[aluminium]]<ref name="HTA" />}}><ref name="ABC" /> ([[torpex]])
|filling=
|filling_weight= 520&nbsp;g [[Hexogen]] for air-to-air role
| filling_weight = {{convert|520|g|lb|abbr=on|sigfig=3}}<ref name="HTA" />
|detonation=
| detonation =
|yield=
| yield =
}}
}}
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[[File:Me 262 with R4M installation.JPG|thumb|Me 262 with R4M underwing rockets on display at the [[Technikmuseum Speyer]], Germany]]
The '''R4M''' ({{lang-de|'''R'''akete, '''4'''Kilogramm, '''M'''inenkopf}}) rocket, nicknamed the ''Hurricane'' ({{lang-de|Orkan}}) due to its distinctive smoke trail when fired, was an [[anti-aircraft]] [[Air-to-air rocket|rocket]]. It was developed by the [[Germany|German]] [[Luftwaffe]] during [[World War II]].
[[File:Messerschmitt Me 262 at the Evergreen Aviation & Space Museum 2 (cropped).jpg|thumb|Me 262 with R4M underwing rockets on display at the [[Evergreen Aviation & Space Museum]], United States]]
[[File:B-24 Destroyed.jpg|thumb|A [[Consolidated B-24 Liberator|B-24]] shot down by [[Rudolf Rademacher]] with the R4M]]


'''R4M''', abbreviation for ''Rakete, 4 kilogramm, Minenkopf'' ({{langx|en|Rocket, 4 kilogram, Mine-head}}),<ref name="ABC">{{cite web|title=R4M Orkan|url=http://www.germanluftwaffe.com:80/archiv/Dokumente/ABC/f/Flakraketen/R4M%20Orkan/R4M%20Orkan.html|url-status=dead|archive-url=https://web.archive.org/web/20180319104249/http://www.germanluftwaffe.com:80/archiv/Dokumente/ABC/f/Flakraketen/R4M%20Orkan/R4M%20Orkan.html|archive-date=2018-03-19|access-date=2021-06-22|website=germanluftwaffe}}</ref> also known by the nickname ''Orkan'' ({{langx|en|Hurricane}}) due to its distinctive smoke trail when fired, was a folding-fin [[air-to-air rocket]] used by the [[Luftwaffe]] at the end of [[World War II]].
⚫
==Development==
⚫
The R4M was developed in order to deal with the increasing weight of anti-bomber weapons being deployed by Luftwaffe fighters. The primary anti-bomber weapon of the Luftwaffe for much of the war was the 20&nbsp;mm [[MG 151/20 cannon|MG 151/20]] [[autocannon]], which was compact enough to be mounted in an internal wing bay mounting in the [[Focke-Wulf Fw 190]] (up to 4 cannon, or 6 with optional twin-gun underwing pods) and also fitted on the centerline of [[Messerschmitt Bf 109|Bf 109G]] fighters, firing through the propeller spinner as a ''Motorkanone''. This could be supplemented by an additional pair of cannon in drag-inducing underwing [[Gun pod|gun pods]], but it was found that it took an average of twenty 20&nbsp;mm hits to shoot down a typical four-engined Allied bomber. The MG 151/20 was subsequently supplemented with or replaced by the 30&nbsp;mm [[MK 108 cannon]], which replaced the centerline ''Motorkanone''-mount MG 151/20 on many Bf 109's, and could be fit into slightly larger underwing pods, which could be used on either the Bf 109 or Fw 190. This heavier-[[Caliber (artillery)|caliber]] cannon could bring down a bomber with an average of one to three hits. However the [[MK 108 cannon|MK 108]] was much heavier and the larger calibre ammunition made it difficult to carry more than one or two "passes" worth. Worse, the low [[muzzle velocity]] of this gun meant it had a very short range and suffered a [[bullet drop|ballistic drop]] of over 41 metres at 1,000 metres range after firing. In approaching close enough to get hits, the fighters placed themselves within the range of the dozens of [[M2 Browning#Aircraft guns|AN/M2 "light barrel" Browning]] defensive machine guns that a combat box formation of a typical USAAF heavy bomber raid possessed, from nearly any approach direction. The more powerful [[MK 103 cannon]] had higher muzzle velocity and increased range, at the cost of greatly increased weight, size (barrel length of 1.34 meters, or 52-3/4 inches) and much lower rate of fire: 380-420 RPM vs. 600-650 RPM for the [[MK 108 cannon|MK 108]].


The R4M was used on several late war German combat aircraft, most notably the [[Messerschmitt Me 262]], and could be fired from open ramps under aircraft wings or from tubes inside under-wing [[rocket pod]]s.<ref name="ABC" /> It featured a high capacity "[[mine shell]]" equivalent [[warhead]] filled with {{convert|520|g|lb|abbr=on|sigfig=3}} of the explosive-mixture ''HTA 41''<ref name="ABC" /> (also known as ''HTA 15''),<ref name="HTA">{{cite book|last=Koch|first=Ernst-Christian|url=https://books.google.com/books?id=ZOsUEAAAQBAJ&dq=%22HTA+41%22+TNT+Aluminium+Hexogen&pg=PA396|title=High Explosives, Propellants, Pyrotechnics|publisher=Walter de Gruyter GmbH & Co KG|date=2021-01-18|pages=936, 937|isbn=9783110660562}}</ref> which consists of 40% [[Hexogen]] ([[RDX]]), 45% [[TNT]] and 15% [[aluminium]].<ref name="HTA" /> The shell-walls of the warhead were only {{convert|0.8|mm|in|abbr=on|sigfig=3}} thick.<ref name="ABC" />
⚫
Also, the [[21 cm Nebelwerfer 42|Nebelwerfer]] 42-derived ''[[Werfer-Granate 21]]'' (Wfr. Gr. 21, or ''Bordrakete'' BR 21) rockets fitted to Messerschmitt Bf 109 and [[Messerschmitt Bf 110|Bf 110]], and Focke-Wulf Fw 190 fighters, used to break up the [[United States Army Air Forces|USAAF]] [[combat box]] bomber formations, had launch tubes that were not only drag-producing, due to their exposed five-strut under-wing mounting, but also from the fact that the launch tubes needed to be aimed upwards at some 15° from level flight, to counter the BR 21 rocket projectile's considerable ballistic drop after firing. This added to the already considerable drag the launch tube mountings created, and contributed to the Wfr. Gr 21's relatively slow projectile velocity of 1,150&nbsp;km/h (715&nbsp;mph), approximately the same as the [[MK 108 cannon]]'s shells.


Besides the air-to-air warhead the rocket could also be outfitted with [[shaped charge]] warheads for air-to-ground use, then called R4HL for ''hohlladung'' ({{langx|en|[[hollow charge]]}}).<ref name="ABC" /> These warheads were called ''[[Panzerblitz (missile)|Panzerblitz]]'' ({{langx|en|Armor-lightning}}) and existed in two primary versions: ''Panzerblitz&nbsp;2'' (''PB&nbsp;2''), consisting of an 88&nbsp;mm [[Panzerschreck]] warhead fitted with a ballistic cap, and ''Panzerblitz&nbsp;3'' (''PB&nbsp;3''), consisting of the original 55&nbsp;mm mine-warhead modified to be a shaped-charge.<ref>{{cite web|title=The Panzerschreck ammunition, Alternative use|url=https://www.bergflak.com/psammo.html|access-date=2021-06-22|website=bergflak.com}}</ref><ref>{{cite book|title=Unknown! N.5|author1=J. Miranda |author2=P. Mercado }}</ref>
⚫
The solution was to replace the underwing gun pods, and the excessively drag-producing large-calibre underwing rocket launch tubes, with a small-diameter solid-fuel rocket-engine-propelled projectile, mounting a warhead similar to that of the cannon shell. Although each "round" was heavier than the corresponding gun-fired shell, the absence of a gun reduced the overall weight considerably. The weight difference was so great that even a much larger and longer-ranged rocket was still lighter than the guns it could replace, although the total number of rounds carried was also reduced from 65 rounds of 30&nbsp;mm ammuniton to only 24 rockets.


⚫
== Development ==
⚫
The anti-aircraft version of the R4M used a large warhead of 55&nbsp;mm with 520&nbsp;g. (17.6 ounces) of the strongly [[Brisance|brisant]] [[Hexogen]] explosive charge, nearly guaranteeing a fighter kill with one hit, from the "shattering" force of its explosive warhead — this was the same explosive used in the shells fired by both the [[MK 103 cannon|MK 103]] (30&nbsp;x&nbsp;184&nbsp;mm cartridge) and [[MK 108 cannon|MK 108]] (30&nbsp;x&nbsp;90&nbsp;mm cartridge) autocannons. Each R4M weighed 3.2&nbsp;kg and was provided with enough fuel to be fired from 1000&nbsp;m, just outside the range of the bomber's defensive guns. The main body of the rocket consisted of a simple steel tube with eight base-hinged flip-out fins on the tail for stabilisation, deployed immediately after launch. A battery typically consisted of two groups of 12 rockets and when all 24 were salvoed in an attack, they would fill an area about 15 by 30&nbsp;m at 1000&nbsp;m, a density that made it almost certain that the target would be hit. The R4Ms were usually fired in four salvos of six missiles at intervals of 70 milliseconds from a range of 600&nbsp;m, and would supersonically streak towards their target at a sixty percent higher velocity than the [[Werfer-Granate 21|Wfr. Gr. 21]]'s rockets would (the BR 21's projectile travelled at some 1150&nbsp;km/h post-launch), as the R4M typically had a flight speed of roughly 1,890&nbsp;km/h (1,175&nbsp;mph). Two warheads were available for the R4M, the common '''PB-3''' with a 0.4&nbsp;kg charge for [[anti-aircraft]] use and the larger shaped charge, similar in construction to the [[Panzerschreck]], the [[Panzerblitz_(missile)|Panzerblitz]] (PB-2/3), for [[anti-tank]] use. The ''Panzerblitz III'', mounting a gigantic 210&nbsp;mm [[hollow charge]] warhead (the same calibre as the BR 21), can be seen as the ultimate development of the basic ''Orkan'' rocket. It was intended to be carried (six or eight rockets per plane) by the [[Anti-tank rocket|tank-busting]] B model of the [[Henschel Hs 132]] jet [[dive-bomber]] - however, neither the missile nor the warplane it was exclusively intended for got beyond the prototype stage before the end of the war.
{{More citations needed section|date=September 2021}}
⚫
The R4M was developed in order to deal with the increasing weight of anti-bomber weapons being deployed by Luftwaffe fighters. The primary anti-bomber weapon of the Luftwaffe for much of the war was the 20&nbsp;mm [[MG 151/20 cannon|MG 151/20]] [[autocannon]], which was compact enough to be mounted in an internal wing bay mounting in the [[Focke-Wulf Fw 190]] (up to 4 cannon, or 6 with optional twin-gun underwing pods) and also fitted on the centerline of [[Messerschmitt Bf 109|Bf 109G]] fighters, firing through the propeller spinner as a ''Motorkanone''. This could be supplemented by an additional pair of cannon in drag-inducing underwing [[gun pod]]s, but it was found that it took an average of twenty 20&nbsp;mm hits to shoot down a typical four-engined Allied bomber. The MG 151/20 was subsequently supplemented with or replaced by the 30&nbsp;mm [[MK 108 cannon]], which replaced the centerline ''Motorkanone''-mount MG 151/20 on many Bf 109's, and could be fitted into slightly larger underwing pods, which could be used on either the Bf 109 or Fw 190. This heavier-[[Caliber (artillery)|caliber]] cannon could bring down a bomber with an average of one to three hits. However, the [[MK 108 cannon|MK 108]] was much heavier and the larger calibre ammunition made it difficult to carry more than one or two "passes" worth. Worse, the low [[muzzle velocity]] of this gun meant it had a very short range and suffered a [[bullet drop|ballistic drop]] of over 41 metres at 1,000 metres range after firing. In approaching close enough to get hits, the fighters placed themselves within the range of the dozens of [[M2 Browning#Aircraft guns|AN/M2 "light barrel" Browning]] defensive machine guns that a combat box formation of a typical USAAF heavy bomber raid possessed, from nearly any approach direction. The more powerful [[MK 103 cannon]] had higher muzzle velocity and increased range, at the cost of greatly increased weight, size (barrel length of 1.34 meters, or 52-3/4 inches) and much lower rate of fire: 380-420 RPM vs. 600-650 RPM for the [[MK 108 cannon|MK 108]].


⚫
Also, the [[21 cm Nebelwerfer 42|Nebelwerfer]] 42-derived ''[[Werfer-Granate 21]]'' (Wfr. Gr. 21, or ''Bordrakete'' BR 21) rockets fitted to Messerschmitt Bf 109 and [[Messerschmitt Bf 110|Bf 110]], and Focke-Wulf Fw 190 fighters, used to break up the [[United States Army Air Forces|USAAF]] [[combat box]] bomber formations, had launch tubes that were not only drag-producing, due to their exposed five-strut under-wing mounting, but also from the fact that the launch tubes needed to be aimed upwards at some 15° from level flight, to counter the BR 21 rocket projectile's considerable ballistic drop after firing. This added to the already considerable drag the launch tube mountings created, and contributed to the Wfr. Gr 21's relatively slow projectile velocity of {{Convert | 1150 | km/h | m/s mph | abbr = on}}, approximately 60% of the {{Convert | 505 | m/s | mph | -1 | abbr = on}} velocity of the [[MK 108 cannon]]'s shells.
⚫
==Operations==

⚫
[[File:Me 262 with R4M installation.JPG|thumb|Me 262 with R4M underwing rockets on display at the [[Technikmuseum Speyer]], Germany]]
⚫
The solution was to replace the underwing gun pods, and the excessively drag-producing large-calibre underwing rocket launch tubes, with a small-diameter solid-fuel rocket-engine-propelled projectile, mounting a warhead similar to that of the cannon shell. Although each "round" was heavier than the corresponding gun-fired shell, the absence of a gun reduced the overall weight considerably. The weight difference was so great that even a much larger and longer-ranged rocket was still lighter than the guns it could replace, although the total number of rounds carried was also reduced from 65 rounds of 30&nbsp;mm ammunition to only 24 rockets.
⚫
Only a small number of aircraft were fitted with the R4M, mostly [[Messerschmitt Me 262]]s and the ground attack version of the [[Fw 190]]s, which mounted them on small wooden racks under the wings. On one occasion, a [[Me 163]]A was fitted with several R4M rockets, and this setup was tested for several weeks in 1944, without incident. This was the first time a rocket propelled aircraft has had rocket propelled armament.

[[File:R4M AT version.jpg|thumb|upright=1.0|left|Anti-tank version of the R4M rocket on display at the [[Steven F. Udvar-Hazy Center]].]]
⚫
The anti-aircraft version of the R4M used a large warhead of 55&nbsp;mm with {{Convert | 520 | g | abbr = on}} of the strongly [[Brisance|brisant]] [[Hexogen]] explosive charge, nearly guaranteeing a fighter kill with one hit, from the "shattering" force of its explosive warhead — this was the same explosive used in the shells fired by both the [[MK 103 cannon|MK 103]] (30&nbsp;x&nbsp;184&nbsp;mm cartridge) and [[MK 108 cannon|MK 108]] (30&nbsp;x&nbsp;90&nbsp;mm cartridge) autocannons. Each R4M weighed 3.2&nbsp;kg and was provided with enough fuel to be fired from 1000&nbsp;m, just outside the range of the bomber's defensive guns. The main body of the rocket consisted of a simple steel tube with eight base-hinged flip-out fins on the tail for stabilisation (patented by [[Edgar Brandt]] in 1930<ref>{{US patent|1879840A}}</ref> and also used on the contemporary [[M8 rocket]]), deployed immediately after launch. A battery typically consisted of two groups of 12 rockets and when all 24 were salvoed in an attack, they would fill an area about 15 by 30&nbsp;m at 1000&nbsp;m, a density that made it almost certain that the target would be hit. The R4Ms were usually fired in four salvos of six missiles at intervals of 70 milliseconds from a range of 600&nbsp;m, and would supersonically streak towards their target at a sixty percent higher velocity than the [[Werfer-Granate 21|Wfr. Gr. 21]]'s rockets would (the BR 21's projectile travelled at some 1150&nbsp;km/h post-launch), as the R4M typically had a flight speed of roughly {{Convert | 1890 | km/h | abbr = on}}. Two warheads were available for the R4M, the common '''PB-3''' with a 0.4&nbsp;kg charge for [[anti-aircraft]] use and the larger shaped charge, similar in construction to the [[Panzerschreck]], the [[Panzerblitz (missile)|Panzerblitz]] (PB-2/3), for [[anti-tank]] use. The ''Panzerblitz III'', mounting a gigantic 210&nbsp;mm [[hollow charge]] warhead (the same calibre as the BR 21), can be seen as the ultimate development of the basic ''Orkan'' rocket. It was intended to be carried (six or eight rockets per plane) by the [[Anti-tank rocket|tank-busting]] B model of the [[Henschel Hs 132]] jet [[dive-bomber]] - however, neither the missile nor the warplane it was exclusively intended for got beyond the prototype stage before the end of the war.

⚫
== Operations ==
⚫
Only a small number of aircraft were fitted with the R4M, mostly [[Messerschmitt Me 262]]s and the ground attack version of the [[Focke-Wulf Fw 190|Fw 190]]s, which mounted them on small wooden racks under the wings. On one occasion, a [[Me 163]]A was fitted with several R4M rockets, and this setup was tested for several weeks in 1944, without incident. This was the first time a rocket propelled aircraft has had rocket propelled armament.<ref>{{cite book |last1=Ziegler |first1=Mano |url=https://archive.org/details/rocketfighter00mano |title=Rocket Fighter |date=July 1984 |publisher=Bantam Books |isbn=0-553-27348-5 |edition=2nd |location=New York City |pages=[https://archive.org/details/rocketfighter00mano/page/155 155–156] |url-access=registration}}</ref>

⚫
The Luftwaffe found the R4M missiles to have a similar trajectory to the 30&nbsp;mm [[MK 108 cannon]]'s rounds in flight, so the standard Revi 16''B'' gunsight could be utilized.<ref name="EthellPrice1994">{{cite book|author1=Jeffrey L. Ethell|author2=Alfred Price|title=World War II fighting jets|url=https://books.google.com/books?id=AwG-fLv5WlwC|access-date=3 September 2013|date=1 April 1994|publisher=Airlife|isbn=978-1-85310-406-0|page=38}}</ref>

== Technical specifications (R4M) ==
[[File:R-4M_Orkan_(3D-iso).jpg|borderless|600px|right]]
;General
*'''Name''' − Rakete, 4 kilogramm, Minenkopf (R4M)
*'''Type''' − Folding-fin, [[Air-to-air rocket]]<ref name="ABC" />
*'''Total length''' − {{convert|812|mm|in|abbr=on|sigfig=3}}<ref name="ABC" />
*'''Total weight''' − {{convert|3.85|kg|lb|abbr=on|sigfig=3}}<ref name="ABC" />

;Warhead
*'''Type''' − [[High-Explosive, High-Capacity]]<ref name="ABC" />
*'''Caliber''' − {{Convert|55|mm|in|abbr=on|sigfig=3}}<ref name="ABC" />
*'''Length''' − {{convert|200|mm|in|abbr=on|sigfig=3}}<ref name="ABC" />
*'''Wall thickness''' − {{convert|0.8|mm|in|abbr=on|sigfig=3}}<ref name="ABC" />
*'''Explosive Charge''' − {{convert|520|g|lb|abbr=on|sigfig=3}} ''HTA 41''{{efn|name=HTA}}<ref name="ABC" /> ([[torpex]])
*'''[[Fuze]] model''' − ''AzR2'' nose fuze<ref name="ABC" />
*'''Fuze length''' − {{convert|65|mm|in|abbr=on|sigfig=3}} (total), {{convert|15|mm|in|abbr=on|sigfig=3}} (internal)<ref name="ABC" />

;Rocket engine
*'''Diameter''' − {{convert|55|mm|in|abbr=on|sigfig=3}} (engine)<ref name="ABC" />
*'''Length''' − {{convert|410|mm|in|abbr=on|sigfig=3}} (engine), {{convert|148|mm|in|abbr=on|sigfig=3}} (tail section)<ref name="ABC" />
*'''Fin-span''' − {{convert|242|mm|in|abbr=on|sigfig=3}}<ref name="ABC" />
*'''Fin-swivel''' − 100°<ref name="ABC" />
*'''Propellant type''' − Solid fuel [[diethylene glycol]] tube<ref name="ABC" />
*'''Propellant dimensions''' − {{convert|340|mm|in|abbr=on|sigfig=3}} (length), {{convert|12|mm|in|abbr=on|sigfig=3}} (internal diameter), {{convert|45|mm|in|abbr=on|sigfig=3}} (external diameter)<ref name="ABC" />
*'''Propellant weight''' − {{convert|0.815|kg|lb|abbr=on|sigfig=3}}<ref name="ABC" />
*'''Combustion chamber''' − {{convert|2.5|mm|in|abbr=on|sigfig=3}} thick venturi-pipe ending with a [[nozzle]]<ref name="ABC" />
*'''Nozzle dimensions''' − {{convert|110|mm|in|abbr=on|sigfig=3}} (length), ({{convert|13|mm|in|abbr=on|sigfig=3}} (internal top diameter), {{convert|45|mm|in|abbr=on|sigfig=3}} (internal base diameter)<ref name="ABC" />

;Performance
*'''Max thrust''' − {{convert|245|kp|lbf|abbr=on|sigfig=3}}<ref name="ABC" />
*'''Burn time''' − 0.75 s<ref name="ABC" />
*'''Velocity''' − {{convert|525|m/s|ft/s|abbr=on|sigfig=3}} (initial), {{convert|125|m/s|ft/s|abbr=on|sigfig=3}} (at {{convert|1000|m|yd|abbr=on|sigfig=3}})<ref name="ABC" />
*'''Range''' − {{convert|1500|m|yd|abbr=on|sigfig=3}} (max),<ref name="ABC" /> {{convert|600-1000|m|yd|abbr=on|sigfig=3}} (effective)


== Notes ==
⚫
The Luftwaffe found the R4M missiles to have a similar trajectory to the 30&nbsp;mm [[MK 108 cannon]]'s rounds in flight, so the standard Revi 16''B'' gunsight could be utilized.<ref name="EthellPrice1994">{{cite book|author1=Jeffrey L. Ethell|author2=Alfred Price|title=World War II fighting jets|url=http://books.google.com/books?id=AwG-fLv5WlwC|accessdate=3 September 2013|date=1 April 1994|publisher=Airlife|isbn=978-1-85310-406-0|page=38}}</ref>
{{Notelist}}


==See also==
== See also ==
* [[3.5-Inch Forward Firing Aircraft Rocket|3.5-inch FFAR rocket]] (US forces)
* [[3.5-Inch Forward Firing Aircraft Rocket|3.5-inch FFAR rocket]] (US forces)
* [[5-Inch Forward Firing Aircraft Rocket|5-inch FFAR rocket]] (US forces)
* [[5-Inch Forward Firing Aircraft Rocket|5-inch FFAR rocket]] (US forces)
Line 71: Line 117:
* [[RS-82 (rocket family)]] (Soviet Union)
* [[RS-82 (rocket family)]] (Soviet Union)


== References ==
<ref>{{cite book|last1=Ziegler|first1=Mano|title=Rocket Fighter|date=July 1984|publisher=Bantam Books|location=New York, New York|isbn=0-553-27348-5|pages=155-156|edition=2nd}}</ref>==References==
{{reflist}}
{{reflist}}


==External links==
== External links ==
{{Commons category|R4M rocket}}
* [http://www.deutscheluftwaffe.de/archiv/Dokumente/ABC/f/Flakraketen/R4M%20Orkan/R4M%20Orkan.html German language page on details of the R4M unguided rocket, and its ''Panzerblitz'' ground attack version]
* [https://web.archive.org/web/20160101174515/http://www.deutscheluftwaffe.de/archiv/Dokumente/ABC/f/Flakraketen/R4M%20Orkan/R4M%20Orkan.html German language page on details of the R4M unguided rocket, and its ''Panzerblitz'' ground attack version]
{{Use dmy dates|date=June 2017}}
{{WWIIGermanAerialWeapons}}


[[Category:Air-to-air rockets of Germany]]
[[Category:Air-to-air rockets of Germany]]
[[Category:World War II weapons of Germany]]
[[Category:World War II weapons of Germany]]
[[Category:Research and development in Nazi Germany]]
[[Category:Research and development in Nazi Germany]]
[[Category:Weapons and ammunition introduced in 1944]]

Latest revision as of 02:27, 26 October 2024

R4M rocket
R4M "Orkan" on display at the German Museum of Technology
TypeRocket
Place of originGermany
Service history
In service1944-1945
Used byLuftwaffe
WarsWorld War II
Production history
Designed1944
ManufacturerHeber AG, Osterode, Germany
VariantsR4M (air-to-air)[1]
R4HL (air-to-ground)[1]
Specifications
Mass3.85 kg (8.49 lb)[1]
Length812 mm (32.0 in)[1]
Width55 mm (2.17 in)[1]
Muzzle velocity525 m/s (1,720 ft/s)[1]
Effective firing range600–1,000 m (656–1,090 yd)
Maximum firing range1,500 m (1,640 yd)[1]
FillingHTA 41[a]>[1] (torpex)
Filling weight520 g (1.15 lb)[2]
Me 262 with R4M underwing rockets on display at the Technikmuseum Speyer, Germany
Me 262 with R4M underwing rockets on display at the Evergreen Aviation & Space Museum, United States
A B-24 shot down by Rudolf Rademacher with the R4M

R4M, abbreviation for Rakete, 4 kilogramm, Minenkopf (English: Rocket, 4 kilogram, Mine-head),[1] also known by the nickname Orkan (English: Hurricane) due to its distinctive smoke trail when fired, was a folding-fin air-to-air rocket used by the Luftwaffe at the end of World War II.

The R4M was used on several late war German combat aircraft, most notably the Messerschmitt Me 262, and could be fired from open ramps under aircraft wings or from tubes inside under-wing rocket pods.[1] It featured a high capacity "mine shell" equivalent warhead filled with 520 g (1.15 lb) of the explosive-mixture HTA 41[1] (also known as HTA 15),[2] which consists of 40% Hexogen (RDX), 45% TNT and 15% aluminium.[2] The shell-walls of the warhead were only 0.8 mm (0.0315 in) thick.[1]

Besides the air-to-air warhead the rocket could also be outfitted with shaped charge warheads for air-to-ground use, then called R4HL for hohlladung (English: hollow charge).[1] These warheads were called Panzerblitz (English: Armor-lightning) and existed in two primary versions: Panzerblitz 2 (PB 2), consisting of an 88 mm Panzerschreck warhead fitted with a ballistic cap, and Panzerblitz 3 (PB 3), consisting of the original 55 mm mine-warhead modified to be a shaped-charge.[3][4]

Development

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The R4M was developed in order to deal with the increasing weight of anti-bomber weapons being deployed by Luftwaffe fighters. The primary anti-bomber weapon of the Luftwaffe for much of the war was the 20 mm MG 151/20 autocannon, which was compact enough to be mounted in an internal wing bay mounting in the Focke-Wulf Fw 190 (up to 4 cannon, or 6 with optional twin-gun underwing pods) and also fitted on the centerline of Bf 109G fighters, firing through the propeller spinner as a Motorkanone. This could be supplemented by an additional pair of cannon in drag-inducing underwing gun pods, but it was found that it took an average of twenty 20 mm hits to shoot down a typical four-engined Allied bomber. The MG 151/20 was subsequently supplemented with or replaced by the 30 mm MK 108 cannon, which replaced the centerline Motorkanone-mount MG 151/20 on many Bf 109's, and could be fitted into slightly larger underwing pods, which could be used on either the Bf 109 or Fw 190. This heavier-caliber cannon could bring down a bomber with an average of one to three hits. However, the MK 108 was much heavier and the larger calibre ammunition made it difficult to carry more than one or two "passes" worth. Worse, the low muzzle velocity of this gun meant it had a very short range and suffered a ballistic drop of over 41 metres at 1,000 metres range after firing. In approaching close enough to get hits, the fighters placed themselves within the range of the dozens of AN/M2 "light barrel" Browning defensive machine guns that a combat box formation of a typical USAAF heavy bomber raid possessed, from nearly any approach direction. The more powerful MK 103 cannon had higher muzzle velocity and increased range, at the cost of greatly increased weight, size (barrel length of 1.34 meters, or 52-3/4 inches) and much lower rate of fire: 380-420 RPM vs. 600-650 RPM for the MK 108.

Also, the Nebelwerfer 42-derived Werfer-Granate 21 (Wfr. Gr. 21, or Bordrakete BR 21) rockets fitted to Messerschmitt Bf 109 and Bf 110, and Focke-Wulf Fw 190 fighters, used to break up the USAAF combat box bomber formations, had launch tubes that were not only drag-producing, due to their exposed five-strut under-wing mounting, but also from the fact that the launch tubes needed to be aimed upwards at some 15° from level flight, to counter the BR 21 rocket projectile's considerable ballistic drop after firing. This added to the already considerable drag the launch tube mountings created, and contributed to the Wfr. Gr 21's relatively slow projectile velocity of 1,150 km/h (320 m/s; 710 mph), approximately 60% of the 505 m/s (1,130 mph) velocity of the MK 108 cannon's shells.

The solution was to replace the underwing gun pods, and the excessively drag-producing large-calibre underwing rocket launch tubes, with a small-diameter solid-fuel rocket-engine-propelled projectile, mounting a warhead similar to that of the cannon shell. Although each "round" was heavier than the corresponding gun-fired shell, the absence of a gun reduced the overall weight considerably. The weight difference was so great that even a much larger and longer-ranged rocket was still lighter than the guns it could replace, although the total number of rounds carried was also reduced from 65 rounds of 30 mm ammunition to only 24 rockets.

Anti-tank version of the R4M rocket on display at the Steven F. Udvar-Hazy Center.

The anti-aircraft version of the R4M used a large warhead of 55 mm with 520 g (18 oz) of the strongly brisant Hexogen explosive charge, nearly guaranteeing a fighter kill with one hit, from the "shattering" force of its explosive warhead — this was the same explosive used in the shells fired by both the MK 103 (30 x 184 mm cartridge) and MK 108 (30 x 90 mm cartridge) autocannons. Each R4M weighed 3.2 kg and was provided with enough fuel to be fired from 1000 m, just outside the range of the bomber's defensive guns. The main body of the rocket consisted of a simple steel tube with eight base-hinged flip-out fins on the tail for stabilisation (patented by Edgar Brandt in 1930[5] and also used on the contemporary M8 rocket), deployed immediately after launch. A battery typically consisted of two groups of 12 rockets and when all 24 were salvoed in an attack, they would fill an area about 15 by 30 m at 1000 m, a density that made it almost certain that the target would be hit. The R4Ms were usually fired in four salvos of six missiles at intervals of 70 milliseconds from a range of 600 m, and would supersonically streak towards their target at a sixty percent higher velocity than the Wfr. Gr. 21's rockets would (the BR 21's projectile travelled at some 1150 km/h post-launch), as the R4M typically had a flight speed of roughly 1,890 km/h (1,170 mph). Two warheads were available for the R4M, the common PB-3 with a 0.4 kg charge for anti-aircraft use and the larger shaped charge, similar in construction to the Panzerschreck, the Panzerblitz (PB-2/3), for anti-tank use. The Panzerblitz III, mounting a gigantic 210 mm hollow charge warhead (the same calibre as the BR 21), can be seen as the ultimate development of the basic Orkan rocket. It was intended to be carried (six or eight rockets per plane) by the tank-busting B model of the Henschel Hs 132 jet dive-bomber - however, neither the missile nor the warplane it was exclusively intended for got beyond the prototype stage before the end of the war.

Operations

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Only a small number of aircraft were fitted with the R4M, mostly Messerschmitt Me 262s and the ground attack version of the Fw 190s, which mounted them on small wooden racks under the wings. On one occasion, a Me 163A was fitted with several R4M rockets, and this setup was tested for several weeks in 1944, without incident. This was the first time a rocket propelled aircraft has had rocket propelled armament.[6]

The Luftwaffe found the R4M missiles to have a similar trajectory to the 30 mm MK 108 cannon's rounds in flight, so the standard Revi 16B gunsight could be utilized.[7]

Technical specifications (R4M)

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General
  • Name − Rakete, 4 kilogramm, Minenkopf (R4M)
  • Type − Folding-fin, Air-to-air rocket[1]
  • Total length − 812 mm (32.0 in)[1]
  • Total weight − 3.85 kg (8.49 lb)[1]
Warhead
  • Type − High-Explosive, High-Capacity[1]
  • Caliber − 55 mm (2.17 in)[1]
  • Length − 200 mm (7.87 in)[1]
  • Wall thickness − 0.8 mm (0.0315 in)[1]
  • Explosive Charge − 520 g (1.15 lb) HTA 41[a][1] (torpex)
  • Fuze model − AzR2 nose fuze[1]
  • Fuze length − 65 mm (2.56 in) (total), 15 mm (0.591 in) (internal)[1]
Rocket engine
  • Diameter − 55 mm (2.17 in) (engine)[1]
  • Length − 410 mm (16.1 in) (engine), 148 mm (5.83 in) (tail section)[1]
  • Fin-span − 242 mm (9.53 in)[1]
  • Fin-swivel − 100°[1]
  • Propellant type − Solid fuel diethylene glycol tube[1]
  • Propellant dimensions − 340 mm (13.4 in) (length), 12 mm (0.472 in) (internal diameter), 45 mm (1.77 in) (external diameter)[1]
  • Propellant weight − 0.815 kg (1.80 lb)[1]
  • Combustion chamber − 2.5 mm (0.0984 in) thick venturi-pipe ending with a nozzle[1]
  • Nozzle dimensions − 110 mm (4.33 in) (length), (13 mm (0.512 in) (internal top diameter), 45 mm (1.77 in) (internal base diameter)[1]
Performance
  • Max thrust − 245 kp (540 lbf)[1]
  • Burn time − 0.75 s[1]
  • Velocity − 525 m/s (1,720 ft/s) (initial), 125 m/s (410 ft/s) (at 1,000 m (1,090 yd))[1]
  • Range − 1,500 m (1,640 yd) (max),[1] 600–1,000 m (656–1,090 yd) (effective)

Notes

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  1. ^ a b HTA 41 composition: 40% Hexogen (RDX), 45% TNT and 15% aluminium[2]

See also

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References

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  1. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj "R4M Orkan". germanluftwaffe. Archived from the original on 19 March 2018. Retrieved 22 June 2021.
  2. ^ a b c d Koch, Ernst-Christian (18 January 2021). High Explosives, Propellants, Pyrotechnics. Walter de Gruyter GmbH & Co KG. pp. 936, 937. ISBN 9783110660562.
  3. ^ "The Panzerschreck ammunition, Alternative use". bergflak.com. Retrieved 22 June 2021.
  4. ^ J. Miranda; P. Mercado. Unknown! N.5.
  5. ^ U.S. patent 1879840A
  6. ^ Ziegler, Mano (July 1984). Rocket Fighter (2nd ed.). New York City: Bantam Books. pp. 155–156. ISBN 0-553-27348-5.
  7. ^ Jeffrey L. Ethell; Alfred Price (1 April 1994). World War II fighting jets. Airlife. p. 38. ISBN 978-1-85310-406-0. Retrieved 3 September 2013.
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