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Post by isc on Aug 26, 2017 22:41:15 GMT 12
I'v always liked the look of the DH 86, but on reading about it's problems it was a bit of a let down for DH, and British aviation in general at the time. isc
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Post by kiwithrottlejockey on Aug 26, 2017 23:22:29 GMT 12
Yeah, rather a lot of the DH86 aeroplanes crashed....or disappeared. Just ask Queensland And Northern Territory Air Services about it.
The Air Britain book in one of my bookcases titled “The de Havilland Dragon/Rapide Family” has details about the history of the DH86 type, including an entry for every single airframe.
But like others, I do rather like the look of them and its a great pity the last one in NZ wasn't saved.
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Post by madmax on Aug 27, 2017 23:25:28 GMT 12
I seem to recall reading about one of Hollyman Airlines 86s disappearing in Bass Strait enroute to Melbourne.
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Post by Mustang51 on Aug 28, 2017 8:07:53 GMT 12
Pardon my ignorance but what were the colours. I do not know but in my mind's eye I see (wish) the top colour to be emerald green..... probably totally incorrect but .....
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Post by Peter Lewis on Aug 28, 2017 8:35:33 GMT 12
It is strange that the DH86s had such a dodgy time in Australia, but in NZ seemed to run quite well.
Heat, perhaps?
It seems generally accepted that the design was right at the limits of wood and fabric technology.
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Post by Bruce on Aug 28, 2017 9:01:47 GMT 12
Pardon my ignorance but what were the colours. I do not know but in my mind's eye I see (wish) the top colour to be emerald green..... probably totally incorrect but ..... Red top, silver below
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Post by Dave Homewood on Aug 28, 2017 10:14:08 GMT 12
I agree Peter, the DH86's seemed perfectly fine in New Zealand service without any incident, so I too have wondered why ours were so good and other nations had so many losses.
All three of ours were damaged or destroyed in incidents in Fiji though. One failed to get airborne on take off and hit a fence and was destroyed. Another was taxied into a ditch by a ground staff member and written off. And the third swung on take off and also went into a ditch. That one returned to NZ and was rebuilt and flew on, even being loaned back to Union Airways, and sadly being broken up postwar. I wonder if the two take off incidents were also heat related. They were in November and December, the hot season.
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Post by Dave Homewood on Aug 28, 2017 10:16:12 GMT 12
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Post by madmax on Aug 28, 2017 11:50:01 GMT 12
As a youngster I remember my father often talked about the problems experienced in Australia with the DH86.
If I recall correctly the early 86er's suffered a stability problem although I cannot remember if it was longditudinal or a yaw problem. One model did have small vertical fins fitted to its stabilizer. I have details about the problem somewhere among my archives and will look them up when I'm home next week.
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Post by davidd on Aug 28, 2017 12:19:23 GMT 12
I recall that the Sir Bruce Stewart movie (the subject of a thread on this Board many years ago) confirms that the colours shown in the advertisements (and the model) are pretty well on the mark. Note however that the first (large) advertisement shows the Union Airways aircraft as DH 86Bs (with end plate auxiliary fins and higher operating weight) which of course were never true of the NZ examples. Strangely all earlier DH 86s in the UK were compulsorily upgraded to DH 86B standard, but apparently NZ was seemingly not concerned with such niceties. It would be interesting to see the full engineering files for the three NZ aircraft on this point, as they could hardly have been ignorant of these modifications. Incidentally the RNZAF DH86 which was written off in a take off accident (NZ554) was at Ohakea, not in Fiji; that was in November 1940 from memory. Also interesting that the last DH 86 flying in the UK (G-ACZP, built 1935) was written off in an accident (non-fatal) in Spain in Sept 1958, and another of the prewar DH86Bs was flying in Turkey (last of four delivered to this operator), presume on scheduled airline operations until 1963 at least! Certainly quite a number of the type suffered serious accidents, etc, but whenever one airline offered examples of the type for sale on second hand market, there always seemed to be willing buyers, whether in the UK or overseas, so perhaps their operating economics were not too bad. However in New Zealand with Union Airways, the annual C of A inspections required that the entire aircraft be completely stripped down, then totally recovered, a mammoth undertaking which must have consumed thousands of skilled man hours labour (and an awful lot of Irish linen!) According to the late E R (Eric) McDonald, chief inspector of UAW at the time, and for a long time afterwards, the airline became very skilled at rigging these rather lanky biplanes which meant that they flew straight and true, but when the DH Company at Rongotai (which had no previous experience on the type) put together the last survivor in 1945 (NZ553/ZK-AHW) this lack of experience showed up badly, and none of the pilots liked it anymore; its service was quite brief, and as soon as enough Lodestars and Electras were in service this aircraft was promptly withdrawn and reduced to scrap (the point being made that the hangar space it now permanently occupied was required for more useful aircraft!). The only components worth retaining parts were the Gipsy Six engines (which at a pinch could and were utilised by RNZAF Dominies) and such items as seats and instruments. The "problems" experienced by the DH 86s were, according to A J Jacksons 'British Civil Aircraft 1919 - 1962, Vol 3 (pages 131-132) were as follows. "After the loss of British Airways' G-ADYF in September 1936, 'YH (G-ADYH) was the subject of a Martlesham report criticizing rudder and aileron control which led to the attachment of large auxiliary fins to the end of the tailplane. In this form the aircraft was known as the DH 86B, to which standard all existing DH 86As were then modified (in 1937). According to same source, the description of the loss of ADYF was: "crashed on night take-off at Gatwick 15.9.36." In very general terms that is also pretty much what happened to our own NZ554 (ex ZK-AEH) at Ohakea, although that was under wartime conditions and crew was engaged on an operational flight to hunt for German raiders in the Tasman Sea; apparently the captain attempted a take off downwind, although this seems to have been a result of confusion in communications prior to take off, and a sudden last-minute change in wind direction, and it was a very dark night. David D
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Post by Dave Homewood on Aug 28, 2017 12:28:36 GMT 12
Oh yes, you're quite correct that one of them was written off at Ohakea, my mistake. Had it not been, it would have probably gone to Fiji too.
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Post by isc on Aug 28, 2017 14:29:12 GMT 12
I believe that there was a problem with the wing twisting if the aelerons were used too violently, and a mod was introduced to increase the bracing of the wings, although like the tailplane end plates(Zulu Shields) this does not seemed to have happened in NZ, or Australia. I think the main plroblem was that the aircraft was built in a very short time, and later machines , DH 89 learned from the failures of the DH 86. isc
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Post by Mustang51 on Aug 28, 2017 14:31:21 GMT 12
Thinks RAAF operasted one in WW.II in Western desert as an air ambulance........plenty of hot weather to contend with there !
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Post by Mustang51 on Aug 28, 2017 14:37:45 GMT 12
Thinks 2..... if the DH.86 had longitudinal instability problems why were endplates fitted a la floatplane Birdog and not just extend the dorsal fin as they did with the Iraqi DH.84M for the Iraq Air Force?
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Post by isc on Aug 28, 2017 22:41:00 GMT 12
The end plates on the tailplane would increase the effective span of the tailplane, probably more than effecting the longatudinal stability. isc
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Post by Mustang51 on Aug 29, 2017 9:10:05 GMT 12
I'm no aerodynamicist but thought it would provide more keel surface for longitudinal stability like when they increased the dorsal on the P.51D to make up for the loss of fuselage when they went from the "high-back". Over to the wizards for that answer. Apparently Birdog with floats but without the endplates snakes all over the place.
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Post by markrogers on Aug 29, 2017 9:39:12 GMT 12
Interesting to note that the DH86's in NZ were rigged properly by Union Airways, they flew true and straight. What was the rigging specifically? And was it to do with the bracing wires on the wings or was it something else? I wonder if DH plans for the DH86 still exist, and if so, a replica could be built. Anything is possible these days...note the reproductions coming back into the air, like TVA's WW1 aircraft for example.
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Post by davidd on Aug 29, 2017 10:16:39 GMT 12
Rigging an aircraft for flight is a very old art (plumb bobs, straight edges, tape measures and small spanners, and the old techniques of trammelling), but it is not rocket science. Most small boys who grew up between the 192Os to the 1960s or 70s will be familiar with the general ideas of trimming a flying model for flight. One of the original trades in the RFC was aircraft rigger, and rigging, de-rigging and re-rigging aircraft probably consumed the majority of their work-time, as the "flying steeds" in their charge spent the majority of their lives out in the open on the fields of France and the UK in all weathers. Aircraft of that era were infinitely adjustable in just about every detail - modern aircraft are probably less so, although they are also required to be perfectly trimmed for flight, and of course are also trimmable during flight by use of various controls. The predominantly wooden aircraft of the 1910s to the WW2 period were adjusted by turnbuckles acting on the numerous rigging wires which stressed the entire aircraft primary structure, and the wires and rods of the flying and engine controls also had to be set up correctly. Many of these comments still hold true today, although not all be any means. David D
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Post by gustav10 on Aug 29, 2017 10:36:13 GMT 12
For further insight into the problems these aircraft suffered I would recommend Arthur Jobs book Aircrash Vol 1 which covers in detail, the saga of the DH86. A fascinating read.
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Post by isc on Aug 29, 2017 22:24:08 GMT 12
As well as the flying and landing wires between the wings, there are bracing wires inside the wing, all adjustable. isc
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