'Threads'
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A Compilation of Two Discussions about Spitfire Wing Skin Stiffeners
source: Hyperscale
(thanks to Brett Green for permission)
(Bold Italics are added by the Webmaster to clarify the text or correct known errors. Some comments and their order of appearance in the original forum have been edited for clarity)
Terry Campion
I need help, because....
Sat Oct 11
I want to build the Tamiya Spitfire Mk.Vb in 1/48th as a D-Day machine (using
the excellent new Model Alliance book as a source). The aircraft I want to model
has clipped wings, late Mk.IX exhaust stubs, coded AZ*B, BL415.
BUT, has it the wing-strengthening bars over the wheel bays??
Also, are these post-war additions to restored airframes??
Thanks in advance from all you Spitfire experts.
Roy Sutherland
Spitfire wheelbay details
Sat Oct 11 19:01:27 2003
From what I remember doing the research on building Jeffrey Northcott's
EP120 (which still flies and does have the mainwheel bay skin stiffeners) some
Mk.Vbs have it and some don't. Why? I couldn't tell you. Check photos of your
subject if you are lucky enough to have one that shows this detail. Few do!
(snip)
There seems to be no hard and fast rules about the Spitfire, though, and endless
variations can be found when you really study wartime pictures.
Graham Boak
Almost certainly
Sat Oct 11
As these were a wartime addition to compensate for the structural weakness above
the wheelbay on the 'a' and 'b' wings.
It would be astonishing if they were not there.
(snip)
Edgar Brooks
Sat Oct 11 16:11:18 2003
(snip) The Mk.I, based near me, has wing stiffeners, on one wing replaced during
the war, and, in a recent article in Air Enthusiast (no. 95,) there is at least
one photo of an early Mk.IX conversion with wing stiffeners, BR143 of 316
Squadron.
Derek Pennington
According to the Bible (Spitfire, The History), Mod 455 was incorporated on
Sat Oct 11
10/10/41, to stiffen wheel well top skin. This was for the Mk.V. Whether this
meant stiffeners, or just a thick gauge metal is unknown, but a gut reaction
says it would have been the stiffeners. I have read somewhere that this was
retro-actively applied to aircraft at OTUs, which included Mk.IIs.
See page 171, under modifications to Mk.V
Tim Mayberry
Spit. "Wing Stiffening Rails" - a Big Fat Lie?
Sat Oct 11
I'm boppin' along,
working on my second Spitfire of the month, modifying the Tamiya 1/48 Mk.Vb to
the Mk.IIb. I note the instructions read to remove the two raised lines on each
of the wings. I start to wonder, what's the story here, are they just for the
Mk.I? If so, why aren't they on the Tamiya Mk.I wings? So I break both the Aero
Detail early Spitfire book, and the SAM Datafile for the Spitfire. Both books
have photos & captions of the "wing reinforcement strakes" over
the wheel well area of the upper wings. They're even shown & labeled in both
the 1/48 scale drawings for the Mk.I. Yet, I'm sensing there's something Rotten
in
I check out Brett's review of the Tamiya Mk.Vb, and he writes that the strakes
were simply a "museum feature." Sure enough, in all the wartime photos
Spits. in my references, these ribs are nowhere to be found.
I've been duped! Or, I was almost duped! What's interesting is that there are
two different Spits. shown in the Aero Detail book that both have the ribs.
So were these things ever used? Or were they just done in museums, and then
photographed & documented as fact?
Just goes to show, you can't always trust museum photos!
Bob
Swaddling
Retrofitted strengthening strakes
Sat Oct 11
Hi Tim
Unless you are building a model of a museum a/c, don't use one for reliable
wartime reference without having a wartime photo to go by. Spitfire
"a" and "b" wings were retrofitted with the strengthening
strakes and a/c that survived still had them. I have even tried to explain this
to Fine Scale Models with their "no compromise" high priced metal
model Spitfire Mk.Ia. They are depicting DW-K as a Battle of Britain Spitfire
and yet have the strakes added. If I remember correctly, the strakes were added
in November 1941, according to Spitfire the History. The "c" wing
didn't need them but, as was pointed out to me this past week, there is a photo
of a Mk IX with the strakes in place. Goes to show you, reference photos are
best.
The two books that you are referring to are not the best either. Great photos in
the Aero Detail book, but of museum a/c, one with boards across the seat so a
visitor could sit in a Spitfire. Too bad Trumpeter took that to be how Spitfire
seats were made and copied the boards.
The SAM Dataphile book is nice but be careful of the drawings especially the
smaller ones that explain the differences in the Marks. Very misleading and some
just downright wrong.
Graham Boak
On operational aircraft too.
Mon Oct 13
You can see them on the LF Mk.Vbs that were used as late as September
1944. Of course many of these airframes were high-life by then (Clipped, cropped
and clapped).
By mid-late 1942 no Mk.I or II, and a reducing number of Vb, remained in the
front line, so it's no wonder that these stiffeners are most often seen on OTU
or hack aircraft.
I don't recall ever seeing any on overseas Mk.Vbs - comments anyone? This could
imply that they were added to aircraft at MUs on refits after an initial time in
service, rather than a "must apply soonest" on front-line aircraft.
Steve Hawley
War Time Mk Vb Photo
Sun Oct 12
Jim G.
Stiffeners on "high time" airframes ?
I thought that the stiffeners were applied to high-time (war weary)
airframes that were used at OTU's and as "hacks", but not on
operational aircraft. I think I have seen a photo taken from a different angle
of the same Spitfire Mk.V that Steve Hawley posted a photo of. It was
identified as an 8th Fighter or Bomber Command "hack".
Edgar Brooks
Stiffeners
Sun Oct 12
There were three mods to the Mk.V production line, all designed to
stiffen the upper surface. This came up a day or so ago, and I've posted a
fuller answer there. I'm guessing that it was a mod specially for the Mk.V, but
any I or II, needing a new wing, would have received one, too.
Bob Swaddling
Sun Oct 12
Hi Edgar
Check out the Shuttleworth collection's Spitfire Mk.Vc. It even has the
strengthening strakes. I don't know why, but they are on there. I do know that
AR501 was the main Spitfire that was the pattern for Tamiya's Mk.V, but don't
know why they made it into a "b" wing rather than a "c"
which would have made more sense since Hasegawa and Airfix already had Mk.Vb's
in 1/48th scale. (snip)
Graham Boak
Date - that's why.
Sun Oct 12
Most Mk.Vbs were built before the mod was introduced, that's why you won't see
it on many photos - it wasn't there then. But the original request was for a
1944 LF Mk.V, and that's a very different matter.
This business of having one on a Mk.IX is very odd, for the Mk.IXs all had the c
wing, which had thicker skins the wheelwell. So you won't see these strakes on
Mk.Vcs either.
Len Thomson
Strenthening strakes on Spit wings
Sun Oct 12
Hi Graham,
I agree with everything you say, but.....
I bought a book the other week, which clearly show a Spit Mk.IX (one of the
converted Mk.Vs), complete with ‘c’ wing, which DID have the strengthening
strakes over the whell wells. It sure surprised me too. I thought that the
strakes were a feature of the ‘a’ and ‘b’ wings only. Contact me off
board and I can let you have a copy.
Just goes to show that there are always surprises with the Spit
Graham Boak
And the Shuttleworth Mk.Vc....
Mon Oct 13
though I don't think that restored aircraft really count!
The other point of course is that the Spitfire wings were still weak in the
root, as exposed when the pointy-winged Mk.VIIs and VIIIs tried dogfighting at
lower altitudes. It could be that individual examples acquired these stiffeners
as a "belts and braces" approach, perhaps after signs of local
overstressing were found?
Edgar Brooks
Wing strengthening
Sun Oct 12
The wording of mod 455 is interesting; "To stiffen wheel-well top
skin," but the increase in weight was only .3 of a pound. 5 ounces sounds
like thicker material, only, to me. However, two other mods were, also,
introduced into the Mk.V production line; 529, also "To stiffen wheel well
top skin," for the Mk.Vc only, increased the weight by 4.8 pounds, much
more feasible with lumps of metal on the top surface.
Another mod, 532, with the same spec., was introduced to the Mk.Va & Vb,
with a weight gain of 6.3 pounds. I hate trying to make assumptions, but it could
be that the thicker skin didn't work, so a temporary ‘fix’ was applied,
using stiffening bars, not all the same size.
These mods appear in "The Spitfire V Manual," which was printed, for
the
A proper perusal of the drawings would be best, but, when I last heard, the
Graham Boak
But where were the mods applied?
Sun Oct 12
A thicker skin would be applied on the production line only - a reskinning of a
wing is not really on for an MU. Not on a widescale basis. It can't be done
without affecting either the outside lines or the internal structure. However,
the attachment of the external stiffeners is a mod that could readily be
applied, possibly even at squadron level given a suitable kit. They would not
want to be chosen for new aircraft on the production line because of the drag
implications.
These strengtheners are only seen (with one known exception) on 'a' and 'b'
wings. They make sense as a retrospective alteration, whereas the skin
thickening makes sense as a production line change.
I think that you have this the wrong way around. The skin thickening did work -
but could not be applied retrospectively. The external ribs worked too, but were
not a preferred option. With mod numbers so close together, there is no time for
deciding the first one didn't work out in practice - they were applied side by
side: but to different aircraft in different circumstances.
If that is making an assumption then I'm not very sorry - it makes perfect
engineering sense and fits the known data. The one piece I haven't checked is
when the Mk.Vb was superseded in production: I suspect this is before the mod
was introduced but don't think that it affects the logic.
Edgar Brooks
Mods
Sun Oct 12 16:01:22 2003
The first, lightweight, mod 455 was a class 4B
mod, as was no. 529, for the Mk.Vc. Looking at the other class 4B mods, also
listed, it appears likely that they had to be done during production. Mod 532,
for the Mk.Va & Vc, was a class 2 mod, like several others, which
seem to be possible after manufacture. Could explain why it was heavier, too.
Look, I'm not saying that these were the mods; I haven't a clue, but those
strakes would have been heavier than a few ounces. Incidentally, the mods for
the Mk.V production went up to 1111, and deletion of the rudder pedal straps was
only no 1024. If it's anything like where I work, the number of the mod often
bears no relation to the date at which it is introduced.
One thought; as well as the Mk.IX, converted from a Mk.Vc, in the Air Enthusiast
article, the Mk.Vc, at Shuttleworth, has the strakes.
Graham Boak
Interesting classification
Mon Oct 13 03:31:13 2003
Is that a type for 532, should it be Mk.Va and Mk.Vb?
I think your comment on the weights was spot-on, and a useful part of the
description, but this Class 2/4B is even more interesting. A definition of those
would be very helpful.
Dates: it'll relate to the date the man wrote it into the Mods Book. This could
either be the date of acceptance or even the date of conception - probably the
latter as some reference will be needed for the preliminary work and drawings.
Of course neither could be close to the date of introduction. Some mods may take
quite a while between the idea and the acceptance of it, others may take longer
to prepare. I still think that close numbers imply that they were being worked
on in the design team at much the same times, regardless of when they reached
the field.
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