FALCON - AN/APG-13A [Main Title]

Log in to create clips, download free screeners and save clips/films in Collections. Click here to find out more.


  • Title: FALCON - AN/APG-13A [Main Title]
  • Film Number: USA 198
  • Other titles: COLLECTION OF RADAR FILMS FROM TELECOMMUNICATIONS RESEARCH ESTABLISHMENT, MALVERN [Allocated Series Title]
  • Summary: Technical film illustrating the AN/APG-13A Falcon gun director radar system when used for target tracking over land.
  • Description: Titles read: "Overland-Falcon. In airplanes equipped P fire airborne cannon or rockets, the pilot is given a sight and instructed to centre the target on its cross hairs before firing. For short ranges a fixed sight can be used. To obtain hits at long ranges, corrections for the trajectory of the missile are needed. For this purpose the 'Falcon' set (AN/APG-13A) was developed. With it, the radar operator can track the target and thereby crank the necessary correction into the pilot's sight. This works satisfactorily on isolated targets. Over land (sic), such a number of targets generally appears on the Falcon indicator that it is impossible for the radar operator to identify the divided target. A new radar technique is therefor needed. Some time ago, it was proposed to use a conical scan antenna lined up with the sight so that a target on the sight axis will return constant echoes and all other taggers will return echoes which vary as the scanner rotates. Normally, however, detection of the one echo, having constant intensity requires complicated equipment. Overland Falcon uses the conical scan but avoids these difficulties by the use of a new type of presentation. It displays range horizontally, angular rotation of the spinner vertically and echoes as intensity modulation. With this presentation the operator's eye takes over many functions for which circuits are otherwise needed. The constant echoes from the target on the sight axis show up as a vertical line of constant intensity, displayed at the corresponding range. The echoes from any other target, varying in intensity as the spinner rotates, show up as a broken or dotted line at its proper range. In this manner, simultaneous information on many targets is presented, while at the same time the deserted target stands out very clearly. The Falcon system can be made into an Overland Falcon by substitution of an AGS (AN/APG-15) spinner for the endfire antenna, by addition of a subpanel in the indicator and of an elevation control to the antenna. Normal Falcon operation can be restored immediately by throwing a switch. If moderate amounts of off-axis reflections are received from exactly the same range as the on-axis target, then the operator can find the correct target by looking for the line that has minimum modulation. If a particular target area produces an excessive amount of such off-axis reflections, this may make detection impossible. Therefore, the system is not claimed to work in every possible situation. However, it will give range date in areas where multiplicity of targets will make Falcon un-operative. The following film shows a number of approaches on different targets. In each case, the film first shows how the target area looked during the approach and then what was observed on the Overland Falcon indicator. The following items may be noted in this film. 1) It is seen that strong radar reflections from 'undesired' targets are present in several of these pictures and that they do not affect the ability to recognise the desired target. 2) Inspection of the film would show that considerable bouncing occurred during the runs. It causes the spinner axis to deviate materially from the target over appreciable periods: it may even point at an 'undesired' target temporarily and cause its indication to show an unmodulated signal. The same will occur if evasive action is taken by the pilot. This stresses the importance of a running commentary from pilot to radar operator indicating when he is on target and when the scope signals should be disregarded, and also the importance of a simple aided tracking unit. The latter is already in production for Falcon and will also help to override the effects of any 'fading' the signal might have. 3) It should be noted that the half power beam width is approximately 30º and the field of view of the camera covering the target area only 4º by 6º. Thus, appreciable signals can be received from 'undesirable' targets that are within the radar beam but are not shown in the target area pictures. 4) Inspection of the film shows a flicker effect caused by a beat between the vertical sweep rate and the camera frame frequency. This flicker is not observed on the M-scope. 5) When looking at vertical frames of this film, the effect of rapid variations in radar return can be very pronounced, even on the desired target. These variations will be integrated out by the time constant of the eye.
  • Alternative Title: COLLECTION OF RADAR FILMS FROM TELECOMMUNICATIONS RESEARCH ESTABLISHMENT, MALVERN [Allocated Series Title]
  • Colour: B&W
  • Digitised:
  • Object_Number: USA 198
  • Sound: Silent
  • Access Conditions: IWM
  • Featured Period:
  • Production Date: 1944
  • Production Country: United States of America
  • Production Details:
  • Personalities, Units and Organisations:
  • Keywords:
  • Physical Characteristics: Colour format: B&W Sound format: Silent Soundtrack language: None Title language: English Subtitle language: None
  • Technical Details: Format: 16mm Number of items/reels/tapes: 1 Footage: 400 ft ca; Running time: 11 mins ca
  • HD Media:
  • Link to IWM Collections page:

    USA 198

  • Related IWM Collections Objects:

    USA 199 (FALCON - AN/APG-13 [Main Title])
Register