Radars

 

The following documents indicate the type of radar equipment proposed for ARGUS units.  Note the date, very early in the ARGUS program development.

proposedargusradar_0001

proposedargusradar_0002

proposedargusradar_0003

proposedargusradar_0004

proposedargusradar_0005

documents courtesy of Rick M.

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Information in this section is from the declassified document referenced below.  Descriptions are of radar units commonly used by Argus units.

Document excerpts from “HyperWar: U.S. Navy in World War II — Reference Works”

Note:  Not all radars used are shown.

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U.S. Radar

Operational Characteristics of Radar
Classified by Tactical Application
FTP 217

Prepared by Authority of the Joint Chiefs of Staff, by the
Radar Research and Development Sub-Committee of the Joint
Committee on New Weapons and Equipment
1 AUGUST 1943

WASHINGTON, D. C.
The publication “U.S. Radar – Operational Characteristics of Available Equipment Classified by Tactical Application”, short title FTP 217, is issued for the guidance of those concerned in planning of future operations.

FTP 217 is effective upon receipt. It is a SECRET registered publication, and is to be transported, handled, and accounted for by U.S. Navy holders in compliance with U.S. Navy Regulations and the current edition of the Registered Publications Manual or by U.S. Army holders in accordance with A.R. 380-5. The Adjutant General’s Office, Operations Branch, 2-B-939, Pentagon Building, Washington, D.C., is designated as the office of record, for U.S. Army holders.

It is forbidden to make extracts from or to copy this publication without specific authority from The Joint Chiefs of Staff, except as provided for in Article 516 of the Registered Publications Manual.
FTP 217 is not intended for use in aircraft. When not in use, it is to be given secure stowage as provided in the Registered Publications Manual or A.R. 380-5.

/signed/
WILLIAM R. PURNELL
Rear Admiral, U.S. Navy
Deputy Chief of staff
Commander-in-Chief, U.S. Fleet
and Chief of Naval Operations

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Long-Range Aircraft Warning Sets

SCR-270-D Mobile Long Wave Aircraft Warning Set

SCR-270-D

DESCRIPTION: Six-vehicle mobile, long wave early warning aircraft detector. Azimuth and range supplied. Set is equipped with “A” scope.

USES: To establish a screen of warning which provides information of approaching aircraft as early as possible but with a sacrifice of accuracy in range, azimuth and elevation. IFF equipment RC-150 is used.

PERFORMANCE AND SITING:

Maximum range on a single bomber flying at indicated heights, when set is on a flat sea level site:

Altitude, feet           1000                5000                     20,000                          25,000

Range, miles             20                    50                         100                               110

Set should be sited at a height between 100′ and 1000′ above an unobstructed reflecting surface.

TRANSPORTABILITY: Complete set is carried in 6 vehicles, the largest of which measures 30’4″ x 9’10” x 8′. Total weight of shipment is 101,790 lbs; total volume 11,485 cu. ft.

INSTALLATION: Operates from trucks in which mounted. Can be placed in operation about 6 hours after arrival at site.

PERSONNEL: Seven men comprise operating crew. For 24 hour operation about 50 men are required to run radar, communication radio, and camp.

POWER: 15.3 KW, supplied by PE-74, 25 KVA gasoline-driven generator, having fixed consumption of 4 gal. per hour, non-leaded gasoline.

 Radar-SC270

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SCR-271-D and SCR-271-E Fixed Long Wave Aircraft Warning Set

SCR-271-D

DESCRIPTION: Fixed long wave early warning aircraft detector. Azimuth and range supplied on “A” scopes. 271-D has a 100′ tower; 271-E, a 50′ tower.

USES: To establish a screen of warning which gives data on aircraft as early as possible, but with a sacrifice of accuracy in range, azimuth and elevation. IFF equipment RC-151 is used.

PERFORMANCE AND SITING: Maximum range on a single medium bomber flying at indicated altitudes, when set is on a flat sea level site:

Altitude, feet                     1000                         5000                       20,000                          25,000

SCR-271-E Range, miles   20                              50                          100                                110

SCR-271-D Range, miles   25                              60                          120                                135

Sets should be sited so that the mean antenna height is between 100 and 1000 ft. above an unobstructed flat surface. The 100′ tower should be used when it is desired to get additional low coverage, or to insure clearance above surrounding trees or other obstructions.

TRANSPORTABILITY: Sets are packed in 106 units, weighing a total of 42,279 lbs. Largest unit is 176″ x 25″ x 20″. Total volume is 4008 cu. fit.

INSTALLATION: Requires a weatherproof building approx. 20′ x 40′ for housing radar components and a building approx. 20′ x 20′ for housing the power units and switchboard. A 100 foot tower on concrete footings is required for an SCR-271-D and a 50-ft. tower for an SCR-271-3. Buildings and tower are built by engineers in about 3 weeks. Radar can be installed by five men in about two weeks.

PERSONNEL: 7 men are operating crew. For 24 hour operations, about 50 men are required for radar, communication radio, and camp.

POWER: 15.3 KW supplied by PE 74, 25 KVA gasoline-driven generator. Consumption is 4 gal. per hour, non-leaded standard commercial gas.

Radar-SC271

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GCI–Ground or Ship Control of Interception Sets

SCR-527 Mobile Long Wave Aircraft detector and GCI

SCR-527-A

DESCRIPTION: Seven-truck mobile long wave medium-range aircraft detector and GCI. Gives azimuth, range and altitude on PPI and HR scopes.

USES: To provide necessary continuous plan position and accurate relative height of enemy plane and friendly fighter plane for GCI. Set can also be used for early warning and to give increased coverage at low angles of search. IFF equipment RC-127 is used. When operating as a GCI station, VHF equipment SCR-624 is required.

PERFORMANCE AND SITING: Maximum range on a single medium bomber flying at indicated altitudes when set is installed on a flat sea level site:

Maximum range on a medium bomber, with set on flat sea level site:

Altitude, feet           1000                5000                10,000                25,000

Range*, miles           17                     35                       90                     100
*Range of PPI limits GCI operation to about 45 miles.

When operating as GCI, set must be sited so that a flat unobstructed reflecting surface extends at least 1/4th mile in the sector in which height-finding is desired. Good GCI sites are extremely rare, and workable sits are found only with difficulty. When used for early warning, these sets should be sited at a height between 100 and 1,000 feet above an unobstructed reflecting surface.

INSTALLATION: Operates from trucks in which mounted. Can be placed in operation in approximately 6 hours after arrival at proper site.

TRANSPORTABILITY: Set consists of 7 vehicles weighing a total of 97,610 lbs. Largest vehicle measures 26’21/2″ x 8’11/2″ x 10′.

PERSONNEL: 8 men are operating crew. For 24-hour operations, about 54 men are required for operation of radar, communication radio, and camp.

POWER: Supplied by two PE 137-A 25 KW, 120/208 V gasoline generators, one of which serves as a spare. Supplied with set in separate trucks. Fuel consumption is 2.4 gal. per hour of non-leaded standard commercial gasoline.

Radar-SC527A

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SCR-588 Long Wave Aircraft detector and GCI

SCR-588

DESCRIPTION: Fixed medium-range, long wave aircraft detector and GCI. Provides azimuth, range, and altitude data. Type HR and PPI scopes.

USES: To give continuous plan position and accurate relative height of enemy plane and friendly fighter plane for GCI. Set can also be used for early warning and to give increased coverage at low angles of search. IFF equipment RC-188 is used. When operating as GCI, VHF equipment SCR-624 is required.

PERFORMANCE AND SITING:

Maximum range on a medium bomber, with set on flat sea level site:

Altitude, feet           1000                5000                   10,000                     25,000

Range*, miles            20                     50                          95                        105
*Range of PPI limits GCI operation to about 45 miles.

When operating as GCI, set must be sited so that a flat unobstructed surface extends at least 1/4th mile in the height-finding sector. Good GCI sites are extremely rare. For early warning, sets should be sited between 100 and 1,000 feet above an unobstructed surface.

TRANSPORTABILITY: Set is packaged for shipment in 55 units, weighing a total of 54,000 lbs. Largest unit measures 15.3′ x 3.8′ x 1.8′. Total shipping space is 3500 cu. ft.

INSTALLATION: Requires a weatherproof building approximately 20′ x 40′ for housing radar components and a building approximately 20′ x 20′ for power units and switchboard. A 25′ tower on concrete footing is required for support of antenna. Buildings and tower can be built by Engineers in about 3 weeks. Radar can be installed by 5 men in 2 weeks.

PERSONNEL: 8 men are operating crew. For 24-hour operation about 54 men are required to run radar, communication radio, and camp.

POWER: 4 KW at 230 volts and 1 KW at 115 volts, from three PE-198 electric diesel units, supplied with set. (Two units operate simultaneously). Fuel consumption is 21/2 gals. of Diesel fuel oil per hour

Radar-SCR588

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 IFF–Identification Sets

Introduction to IFF

 Transponder — Interrogator-Responsor

IFF is an abbreviation of the phrase “identification of friend or foe.” Since radar is used to direct gun fire or bombing at night, or in daylight when the target is beyond the range of visibility, it is obviously important that there be radar equipment that will serve to identify instantly any aircraft or ship as friend or foe before attack.

There are two basic components in any identification system at present in use: (1) the transpondor, carried by the aircraft or ship to be identified; (2) the interrogator-responsor, or questioning device, located aboard a ship, at a ground station, or in another aircraft.

The transpondor on a plane (or ship) is a combination radio transmitter and receiver, packaged in one small box. Normally, the transpondor is in a receiving condition, and will continue to function as a receiver until it receives a radio signal. Then, the transpondor will automatically become a transmitter and, as such, will transmit a signal in reply to that received. (The transpondor is said to have been triggered.)

In the identification systems now in use the transpondor when functioning as a receiver mechanically sweeps a band (or bands) of frequencies within a few seconds. If during a sweep through the frequency band a radio signal within that band is received, the transpondor will send back the received signal within a fraction of a second, and will transmit the signal on the same frequency on which the signal was received. In effect, then, the transpondor acts as a selective mirror to radio signals.

The interrogator-responsor is also a transmitter and receiver. The transmitter (interrogator) is designed to permit triggering a transpondor. The receiver (responsor) gets the automatic transmitted reply from the transpondor, and by means of additional equipment displays this transmitted reply on a radar scope.

Two IFF systems are in use at present by American and British forces. They are:

(1)          IFF Mark II, and

(2)          IFF Mark III.

Both systems use the same basic components–an airborne (or shipborne) transpondor, and an interrogator-responsor (which in the Mark II system is the search radar)–and operate on the same principle. The basic difference between the Mark II and Mark III systems is that the Mark III is a universal system.

The Mark II transpondors alternately sweep two or three bands of frequencies, but their bands are not common to all transpondors. Mark III transpondors sweep only one band of frequencies. The reason for this difference between the transpondors becomes obvious when their interrogators are examined.

 Mark II System

In general, the Mark II system’s interrogator-responsor unit is the ground, shipborne, or airborne search radar set. In the Mark II system there is no separate interrogator-responsor (IR) unit — the regular radar search equipment, without any extra gadgets, serving as an interrogator-responsor.

Use of the Mark II system has required the airborne transpondors to be capable of replying to all types of radar interrogation employed throughout the various operational areas.

The multiplicity of radar frequencies now being used presents definite limitations to the successful operation of the Mark II system. However, its use continues as an interim measure until all British and American forces are equipped with the several components necessary to operation of the Mark III system.

Since the radar set alone performs the interrogator-responsor function in the Mark II system, the transpondor is triggered (i.e., automatically transmits) each time the transpondor sweeps through the frequency of the interrogating radar. When the transpondor has been triggered, the operator of the interrogating radar will observe on his scope a signal similar to a strong echo at the same or a slightly greater range than the echo made by the reflecting object itself.

The transpondor sweeps through the frequency of the interrogating radar once every six seconds. Because of the regular recurrence rate of the transpondor’s signal (echo), this signal is recognized by the radar operator as an IFF reply.

 Radar-IFFMk2Scope

A typical IFF Mark II scope presentation on an SC-1 radar set is pictured above.

 

Mark III System

 In the Mark III system, identification is accomplished on a single band. This universal Mark III band is designated as “A” band by the Navy, and “I” band by the Army.

The Mark III system requires special interrogator-responsor equipment to be installed to supplement practically all radar sets. Installation of this IR equipment is arranged so that the IFF reply from a transpondor is shown on the interrogating radar’s scope.

Scope presentations vary in the Mark III system. But no IFF signal appears on the radar scope until the interrogator key (challenge switch) has been pressed by the radar operator, unless it so happens that the radar frequency lies within the Navy’s A (Army’s I) band. Below is a picture of an IFF Mark III presentation on the A scope of an SM radar or an SCR-270 radar.

 

 Radar-Mk3Scope

 

After the interrogator key has been pressed by the operator, he then observes that the radar pips denoting friendly planes have corresponding identification pips appearing downward. Therefore, all radar pips not having an identification pip below denote unidentified planes. (On some radar sets the display splits into two, as shown in the picture above). Further substantiating evidence must generally be presented before the term “enemy” can be appended to unidentified planes.

The Mark III reply may be coded to provide additional security and identify special missions.

Mark III G Band

 Besides the universal Mark III band, the Mark III system also has a G band reply for fighter planes only. The Navy A band (Army I) transpondor serves to identify all aircraft (including fighters) as friend or foe on the interrogating radar’s scope; the G band transpondor further identifies friendly fighter aircraft on the interrogating CGI (SCI) radar’s PPI scope.

Reason for the extra G band is that in GCI or SCI work it is often vital to segregate friendly fighters from other friendly or enemy craft so as to organize an interception. The PPI, of course, is the scope used in directing GCI work.

The IFF Mark III G band display is shown only in response to a vocal request from the GCI station. The fighter plane pilot then turns a switch that causes a pattern to appear on the PPI. The IFF signal is symmetrical about the azimuth of the friendly plane. The friendly bomber or enemy plane at the same range as the friendly fighter is thus distinguished, the identity of other planes must be determined on the radar’s A scope.

Interrogators and responsors are invariably used together. In some cases, too, interrogator, responsor and transpondor are all combined in a single unit; this system being known as IRT.

In addition to serving for identification purposes, IFF equipment has other special applications.

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SC, SC-1, SC-2 and SC-3 Long Wave Search for Destroyers and Larger

(**Note:  SC-2 systems were also used as shore based installations – see photos below**)

DESCRIPTION AND USES: Long wave search sets, installed on destroyers and larger ships to search for planes and surface vessels and for control of interception. All sets have an “A” scope, provision for IFF connections, and work with a gyro-compass repeater. SC-2 and SC-3 also have PPI scopes, remote PPI’s, and built-in BL and BI* antennas.

PERFORMANCE: With antennas at 100′, SC and SC-1 (without preamplifier) have a reliable maximum range of 30 miles on medium bombers at 1,000′ altitude. With preamplifier, SC-1’s range is extended to 75 miles — the same as that of SC-2 and SC-3. Range accuracy of SC is ± 200 yards; later models have an accuracy of ± 100 yds. bearing accuracy of SC and SC-21 is ± 5°; of SC-2 and SC-3, ± 3°. There is no elevation control on any of the sets, but height can be estimated roughly from positions of minimum signal strength.

TRANSPORTABILITY: Shipment includes spares for each set. If separate generator is needed, it is included in shipment. Not air transportable.

INSTALLATION: Both SC and SC-1 have 5 components weighing a total of 1800 lbs. SC-2 has 6 components weighing a total of 3,000 pounds. Weights and dimensions of antenna assemblies are 450 lbs. 6’111/2″ x 8’6″ for SC and SC-1; 478 lbs. 4’6″ x 15′ for SC-2 and SC-3. Antennas should be mounted as high as possible, preferably 100 feet or more, above other superstructures.

PERSONNEL: One operator per shift is minimum on all 3 sets.

POWER: SC and SC-1 require primary power of 1500 watts at 115 volts, 60 cycles. SC-2 and SC-3 require 2500 watts at 115 volts, 60 cycles. All sets use ship’s power of 115 volts, 60 cycles; transformer, if ship’s power is 440 volts AC or 220 volts AC; motor generator if ship’s power is DC.
* BI is a component of the Mark IV IFF system omitted from this volume.

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Photos of Radar Installations on Peleliu courtesy of the Estate of Richard W. Heard, Jr. of Argus 20.

SCR-527 Installation

SCR-527 Installation

 

"Restricted" photo classification markings

“Restricted” photo classification markings

 

SC-2 Installation

SC-2 Installation

 

SCR-270 Installation

SCR-270 Installation

 

SC-2 Installation

SC-2 Installation


 

the following photos courtesy of Donald Knotts – photos of Mobile Radar Intercept Team 2 installation Ft. Stevens, Oregon  1945

 

Radar_14

SCR-527 Antenna

 

Radar_13

SCR-527 Antenna

Radar_17

Interior of operations van or truck

 


The following article is from “ALL HANDS” – September 1945 :

ahradar1

ahradar2

ahradar3


 

Illustration of Flight Operations  (FLOPS) room –

FlopsIll

 

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2 comments on “Radars

  1. I have several photographs of the radar antenna deployed on Peleliu by Argus Unit #20. They are not labeled per model, etc. All were classified at the time. If those photographs could be put to use on this page, please contact me offline. Shelley

  2. Great photos from Don Knotts! His father was my high school principal and instrumental in helping me obtain my Ham Radio License which led to becoming a radio operator for the U.S Army Signal Corps. Thank you for your Argus history page. Allen Fenton

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