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Post by shorty on Dec 8, 2009 21:21:19 GMT 12
Early in the war there were insufficient turrets to equip all the Hudsons and towards the end of the war a number of Hudsons were used for transport duties with the turrets removed.
The question is how was the weight and balance of the aircraft maintained? The turret is a fairly hefty lump and is is some distance aft of the C of G so how was it's removal compensated for?
I know that the turret hole covering was steel sheet, presumably as weight saving wasn't required but the steel is fairly thin and not all that heavy so what did they do? Bolt a big lump of lead to the tailwheel? , shift equipment to a more aft location?
I suppose I should have asked my father who worked on them but unfortunatley he died some years ago and I'm hoping not to converse with him for quite some time!
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Post by Bruce on Dec 8, 2009 21:52:04 GMT 12
additional weight would have to go in the tail Shorty - bolting it to the nose would worsen the situation.... (just a typo I guess) If they added weight further aft of the turret cutout, they wouldnt need to add as much - I'm guessing lead or steel ingots behind the aft cabin bulkhead?
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Post by shorty on Dec 8, 2009 22:01:48 GMT 12
ooops, bit of brain fade there. I've amended it to move things in the right direction! I'm off to read my boys book of aircraft weighing now! (and too think I used to do all the aircraft weighing for the RNZAF! Embarassing!)  |
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Post by baz62 on Dec 9, 2009 6:21:25 GMT 12
I remember when they removed the sheetmetal from the Avenger to fit the turret. In place of the turret was a bloody big thick piece of steel with big lead weights bolted to it!! Naturally the steel/aluminum interface created corrosion but no problem for the lads in 7 Hangar!
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Post by shamus on Dec 9, 2009 12:12:31 GMT 12
A photo of a Hudson without a turret landing at Hobsonville. Note their is no covering to the hole, maybe this was put on later.  |
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Post by shorty on Dec 9, 2009 12:21:55 GMT 12
That became NZ 2003 and was the first Hudson to fly in NZ on 20 May 1941. The turret and nose guns didn't arrive until July.
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Post by shamus on Dec 9, 2009 13:07:55 GMT 12
Thanks for that info, Nev. Do you happen to know who did the test flight on NZ2003 (AM591) on
20 May 41. I presume it took place at Hobsonville.
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Post by Dave Homewood on Dec 9, 2009 14:54:53 GMT 12
The pilot for that first Hudson flight in NZ, though not recorded apparently, is thought to have been Flt Lt Jack Busch. He had previously converted to type in Australia and returned to begin the flight test programme for the assembly unit. Pete Jury also tested Hudsons in those early stages but as you and I know, he never flew that first aircraft on its first flight.
That photo is alleged to have been taken on the first flight, and yes it was at Hobsonville. On the 29th of May 1941 it was transferred to Whenuapai and joined No. 1 (GR) Squadron.
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Post by Dave Homewood on Dec 9, 2009 14:56:20 GMT 12
By the way, David Duxbury's notes in the AHNZS journal have that first test flight of the Hudson as the 19th of May 1941, not the 20th.
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Post by Dave Homewood on Dec 9, 2009 15:01:41 GMT 12
Another by the way, the RNZAF Hudson fleet never had sufficient turrets to equip all the aircraft. At any given point only around half of them carried turrets, with priority going to the frontline service aircraft in Fiji, Guadalcanal and Santo, etc. plus a few for the training aircraft for gunnery training. As one frontline aircraft came home for major servicing its turret and radar (if fitted) was removed, put onto another and that second aircraft then flew north with the equipment. So the C-63 transport version was not so much a version with turret removed, they were just the ones not flying with a turret at the time.
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Post by shorty on Dec 9, 2009 15:17:35 GMT 12
So how did they compensate with the C of G?
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Post by shamus on Dec 9, 2009 17:47:24 GMT 12
My notes show that the first Hudson tested by Jury was AM590 on June 11th. 1941 and then NZ2002 on 13 June, followed by 589 on July 1st. 592 on July 3rd. Hudson 2006 followed on Aug.28 and then 2015 on Sept.25. On Sept.26 Hudson 9243, and then 9242 on the same day.
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Post by Peter Lewis on Dec 9, 2009 18:56:56 GMT 12
I heard a related story many years ago - true or not.
The first P-40s arrived crated at Hobsonville before the documentation was available.
Enthusiastic engineers went ahead and assembled the first one anyway. The only components not in the box was the armament, which was following along behind on another ship.
Who needs guns to fly? So an equally enthusiastic test pilot went ahead and flew the thing. Several of his mates also had a go.
Not a problem, it was great.
Then the armament and the documentation turned up. In large letters on page 2 was the stern instruction 'This aircraft must not be flown without the armament fitted, as this will put the C of G outside limits'.
Oh dear, how sad, never mind.
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Post by Dave Homewood on Dec 10, 2009 17:00:59 GMT 12
So how did they compensate with the C of G? I don't know. I have emailed Denys Jones and David Duxbury to see if they have any idea, but nothing heard yet. It's a really good question. I have looked at some interior photos of NZ2031 at MOTAT, which of course has no turret and last flew without a turret as far as I know but cannot see any obvious sign of a removeable ballast. |
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Post by denysjones on Dec 10, 2009 18:28:05 GMT 12
Good question guys.
All I can offer is that 2035 had had a plywood cover fitted to the flat aperture which the lower portion of the turret projected down into the aircraft through and which the mounting ring bolted to. Then the steel plate was attached up and over that. The ply had no holes in it which would indicate any attachment for the ballast. Likewise the next shelf below that in the aircraft is unmarked and all that's left below that level are the toilet, a small stowage locker, and an area through which all the control runs pass.
The turret is a fair old weight all up (two guns, a couple of motors etc etc) so the mass of lead even to compensate for it is going to be a reasonable size so I'm equally keen to find out where it could go. Aft of the turret I doubt as there are cables and de-icer lines there so a shelf would have had to be made and put in.
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Post by Dave Homewood on Dec 10, 2009 19:09:20 GMT 12
Denys, does your museum happen to have any Hudson operating or maintenance manuals that might explain the counter weight situation when the turret was removed?
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Post by angelsonefive on Dec 10, 2009 19:34:25 GMT 12
Could it be that when the Hudson was operated in the passenger carrying role, the human freight made up the weight needed to keep the c-of-g within limits ?
Could it be that there was displayed in the cockpit a conspicuous placard which stated something like " This aircraft is not to be flown with less than X persons in the passenger compartment when the gun turret is not installed." ?
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Post by denysjones on Dec 10, 2009 19:34:32 GMT 12
Sorry Dave no such luck.
AP1690 aka TO 01-75AB-2 has no entries in the index for ballast. The sole mention under turret is the provision for one and the description that the plywood blank and the cover plate are to be fitted in its absence.
In the weight and balance tables they detail weights for the "turret gunner", the "turret guns", the ammunition, and all manner of things (like sextant weighing 3.9lb and located 223.5 inches aft of station 0) but no weight for the turret.
I have to guess it falls under the 552.43lb of "armament provisions (incl gunfire protection)". However just to confuse that it also says elsewhere that "machine guns, mounts, and turret equipment are customer furnished and equipped". So I would assume that they don't call the weight out on the grounds that they don't know what the customer might fit and hence what it might weigh.
So sorry AP1690 fails to clear it up.
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Post by Dave Homewood on Dec 10, 2009 19:49:14 GMT 12
Could it be that when the Hudson was operated in the passenger carrying role, the human freight made up the weight needed to keep the c-of-g within limits ? Could it be that there was displayed in the cockpit a conspicuous placard which stated something like " This aircraft is not to be flown with less than X persons in the passenger compartment when the gun turret is not installed." ? I don't thik that's the answer because there would never have been that many people aboard. As mentioned they flew in operational squadrons without the turret fitted too, so would have to have had a counter-weight of some sort to ballance the trim. Without the turret you're less the turret, guns, ammo and gunner. In the forward area the Hudsons were fitted with beam guns too which I guess must have also altered the C of G a little even though they were nearer to the middle of the aircraft. |
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Post by shorty on Dec 10, 2009 19:59:37 GMT 12
Next time you are doing a interview for your GR Squadrons book Dave perhaps you could ask it of a ex Hudson man.
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