Results 1 to 9 of 9

Thread: Interpretation of ORBs

  1. #1
    Join Date
    Nov 2007
    Location
    Dorset
    Posts
    307
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Default Interpretation of ORBs

    Hi all,
    I've just received some copies of the ORBs for the Ladbergen (DEK) raid for 9 Squadron on 3 March 45. Most of the individual reports are standard stuff, eg:
    "9/10ths stratus, 4/5000. N.W. TI's 22.01 hours 10,000ft."
    Then comes the bit I don't understand, examples are:
    "045T", "036", "0339", "047T", always followed by a RAS. The numbers almost seem like a bearing, but are incomplete?
    Any ideas chaps?
    Regards
    Max

  2. #2
    Join Date
    Nov 2007
    Posts
    1,639
    Thanks
    2
    Thanked 0 Times in 0 Posts

    Default

    RAS stands for Rectified Airspeed, which needs to be calculated to take into account air pressure, instrument error etc. The headings would also have to have been corrected to compensate for these speed corrections.

    A

  3. #3
    Join Date
    Nov 2007
    Location
    Dorset
    Posts
    307
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Default RAS etc

    Thanks Amrit, I knew about the RAS, but you think the preceding numbers or in some cases number/letters combinations are headings then? I don't understand how they apply, and why the "T"?
    Max

  4. #4
    Join Date
    Nov 2007
    Posts
    1,639
    Thanks
    2
    Thanked 0 Times in 0 Posts

    Default

    Using "T"rue North as opposed to Magnetic North?

    A

  5. #5
    Join Date
    Nov 2007
    Location
    Dorset
    Posts
    307
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Default

    That could well be the answer, and if so it would appear to corroborate my suspicions from other reading, nav. plots and studying PRU photos that the attacking planes bombed across the canal, though at an angle, rather than along the route, the same way that the airstrip at Port Stanley in the Falklands was bombed by Vulcan 607 in 1982!
    Max

  6. #6
    Join Date
    Nov 2007
    Location
    Berkshire
    Posts
    2,210
    Thanks
    1
    Thanked 0 Times in 0 Posts

    Default

    Hi Max
    I'm sure that Amrit is correct with the T standing for true but 9 Sqn was 5 Gp and they had their own way of doing things. If you read "Dresden" by Frederick Taylor he explains the much reported use of a sports stadium as an aiming point. It was 5 Gp's and they briefed a/c to pass over the stadium on specific tracks and release their bombs along those tracks to fill up an area of the city. I wonder if the T might also stand for Track. At that stage of the war 9 Sqn were a specialised precision bombing unit using the Tallboy and Grand Slam bombs which worked almost as much by their "earthquake" effect as by blast. The compass bearings/tracks are reasonably clear, could some of the other numbers be time or distance along track as a release point?
    Regards
    Dick

  7. #7
    Join Date
    Nov 2007
    Location
    Dorset
    Posts
    307
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Default The meaning of "T"?

    Thank you Dick for those thoughts. Fortunately, I have a copy of a nav's. plot for the 3 March sortie, from 463 squadron: I'm going to print out the section just aound the target and superimpose the bearings, if that's what they are, from the 9 squadron ORBs to see if it makes sense. I'd like to think so, because as I said in my previous post, it would fit, but also supplement, data already assumed. If not, back to the drawing board!
    The other point that comes up with the ORBs is the time of bombing; I'd read that 9 squadron went in first with their Tallboys, followed by the main force, but all of 9 squadron's bomb release times are very similar to 463 and 467's, ie within a 9 minute (max) window of H-hour which was 22.00.
    Regards
    Max

  8. #8
    Join Date
    Nov 2007
    Posts
    250
    Thanks
    3
    Thanked 0 Times in 0 Posts

    Default

    Hi Max,

    firstly, the "T" does refer to a true compass bearing.

    I believe that it generally common practice in Bomber Command to log the time, height, compass bearing, and airspeed at the time bombs were dropped.

    As has already been suggested, 5 Grp did things a little different at times, and with their own bombing techniques, this Group may have had different log requirements. This may particularly be true for 9 and 617 Squadrons when dropping special munitions. I cannot remember if the SABS bombsight was commonly used at night when dropping with Tallboys, but as this sight relied on accurate input of a number of extra factors (from my dodgy memory - air pressure, drift etc). It could be that the 9 Squadron ORB records some of these extra SABS settings...

    Cheers

    Rod

  9. #9
    Join Date
    Nov 2007
    Location
    Dorset
    Posts
    307
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Default "T"

    Thanks Rod,
    It's always good to hear from you, especially confirming the true bearing. 467 and 463 were of course also part of 5 Group, but their ORBs differ from 9 squadron's only in the respect of not recording the bearing data.
    Incidentally, I asked for an estimate of costs from the NA for the ORBs for that night of 49, 50, 187, 207 and 227 squadrons but they have replied today that "despite their best efforts, they were unable to locate the requested material in the specified document." I was hoping to compare all the ORBs for 3 March but it seems I have more work to do!!
    Regards
    Max

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •