On Mon, 18 Aug 2003 20:39:22 GMT, Guy Alcala
wrote:

Let's just say my reply has been delayed, but here goes.

[snip more gratuitous and unprovoked logical discourse. NB all
gallons referred to in this post are Imperial, not the inferior Yanqui
oppressor's titchy competitive effort.]

[Quill on longitudinal instability on Mk Vs]

Ah, now we can compare close readings and interpretations of same. Onward.
We agree on all the above, but I posit that the commitment would result in a shift to
Mk. VIIIs (or Mk. IXs with similar tankage), accepting the likely temporary decrease
in production.

Actually I don't see there being a production shortfall, except at
Castle Bromwich which would need some retooling to produce Mk VIII
airframes instead of IXs as it ended Vc production in July - October
1943. The rear fuselage tanks could be post-production fittings at
Maintenance Units, which would only receive as many airframes for
fitting as tanks were available. So there'd be two deployment streams
(short-range and long-range Mk VIIIs) until Boulton Paul or whoever
else could produce sufficient tanks for full production fitting.

Much like the behaviour of the actual Mk IX/XVIs with rear-fuselage
tanks in 1945.

True, but those Mk.IX/XVIs also had extra fuel in the regular fuselage tanks (ca.
94-96 gallons, depending on the source) forward of the datum.

66 or 75 gallons according to the Pilot's Notes and Shacklady &
Morgan.

And correct me if I'm
wrong, but ISTR that only those a/c with cut-down rear fuselages got the aft tanks;

Nope: the standard fuselage versions actually got larger internal
rear fuselage tankage - 75 vs 66 gallons. At least that's what the
Pilot's Notes say. [BTW, the VII/VIII/PR.X Pilot's Notes have some
range/climb/cruise graphs which I think might be relevant to this
discussion]

and if you want to extend the escort range it's the amount of fuel you
can carry internally to fight and return on that determines escort radius, no
matter how much fuel you hang externally to boost endurance.

Agreed. This is why the rear-fuselage tankage issue is critical to
this speculation.

Not for combat radius/return, unless you can use rear fuselage tankage for that;
otherwise you're just extending the endurance and ferry range.

This is how Supermarine and the RAF saw it: instability in the early
stages of a flight was acceptable, providing that the fuel load had
been consumed to the point of stability before the aircraft entered
combat. As this is the attitude historically adopted with
rear-fuselage tanks in the Mk IX/XVI, it's not such a stretch to
invoke it a little earlier.

The Mustang could only
retain a fraction (ca. 25-50%) of that rear tank fuel to use for combat without being
dangerously unstable, with the contemporary Spit possibly (probably?) being unable to
retain any of it;

Actually, the relevant testing in January 1945 revealed that the
acceptable manoevering limit with the 75-gallon rear fuselage tank was
9.9 inches aft of the datum, or after 34 gallons had been used.
Clearly the tank didn't need to be emptied for this to be achieved.

at best, it could retain the same fraction as the Mustang. The
Mustang with rear tank didn't have 269 U.S. gallons to fight and return on; it had
somewhere between 205 and 227, depending on what fraction of the aft tank capacity
allowed acceptable combat handling.

In this case we have a Mk IX with 85 gallons internal forward tanks
and about 40 gallons in the rear tank within apparently tolerable
limits for combat.

To be an acceptable long-range escort, the Spit still needed the extra forward
fuselage fuel of the later Mk. IXs and the Mk. VIIIs, plus the leading edge tanks of
the latter. The Mk. VIII carried 124 Imperial gallons internally (149 U.S), ALL of
which was usable in combat, plus whatever extra fuel usable in combat (if any) a rear
tank provided.

Ah, here we disagree: as far as I know, most IX/XVIs didn't have
enlarged forward tanks (in the traditional position forward of the
cabin bulkhead, behind the engine), and most MK VIIIs seem to have
been similar. So the best reliable figure for the internal capacity
of the Mk VIII would actually be around 110 Imp galls. I suppose Air
Commodore Alcala, Director of Fighter Operations in this scenario,
will be pressing the Air Member for Research and Development to get
them all with the enlarged forward tanks as well....

[increased tankage of 2 Spits IXs from Wright Field, July 1944]

In the case of the Spit wing it seems to have been a strength issue, at least
according to Quill

Yes, but I suggest what Wright Field did was a reliable indicator of
what the USAAF would have done if Spitfire production and procurement
was within their grasp. A&AEE whinges about instability would get
short shrift in this situation.

. So I
suggest basic experience of rear-fuselage tankage, and measures to
combat the worst CoG issues resulting were at hand in plenty of time
to have an impact on the postulated fitting of rear-fuselage tanks in
the summer of 1943.

The difference being that the flights to Gibraltar were ferry flights, and no
formation maneuvering or combat flying with the aft tanks full was required.

Sure, but how different is this from Vcs emptying them on the climb
out of East Anglia and the cruise out to Holland? The short-ranged
Spit Vs and IXs could handle combat in those areas, while the LR Spits
would be briefed to pick up their escorts further out over the Zuider
Zee. Giving them an extra 30-45 minutes of flight on internal fuel,
even with the most restricted utility (e.g. only on the way in, no
combat endurance to remain after entering combat) is still of use, and
reflects the utility of giving them drop-tanks to start with. The
final determinant is the distance over enemy territory a Vc could
return on forward tanks alone after exhausting the rear tank, dropping
the 90-gallon drop-tank and spending 10 minutes at high throttle
settings in combat. This is obviously *not* a profile which makes it
contender for deep-penetration escort, but it still means they should
be able to operate out across Holland beyond Amsterdam and up to the
German border. Even a marginal improvement like this would have had a
real and clearly-observable benefit in supressing bomber losses.

In the end, even the RAF cleared the rear-fuselage tanks for
production usage in 1945, and they were happy enough to fit half of
the tankage in the FR XIV and the full thing in the XVIII.

Again, both a/c with cut-down rear fuselages.

Yes, but the cut-down fuselage doesn't seem to be a factor in deciding
whether a Spit got rear-fuselage tanks or not: the IX and XVI with
conventional fuselage got them, the FR XIV got them and I suspect the
XIV would have got them if it hadn't been succeeded on the production
lines by the XVIII in 1945, which only came in a cut-down fuselage
version. As it was, the example of the FR XIV and the IX/XVI
indicates the cut-down fuselage actually had a lower capacity for
rear-fuselage tankage (66 vs 75 gallons).

Getting to our respective readings and
conclusions on Quill, I note that he says in the case of the Mk. 21 that he disagreed
with A&AEE on whether the Mk. 21's handling was acceptable at a certain point, and
that he felt that such handling deficiencies could be accepted to get an a/c with
superior performance into the field (he's also man enough to admit that he may have
been overconfident by this point that average squadron pilots wouldn't have had
serious difficulties, based on his own skills).

I suspect A&AEE were right on that point; but it's instructive to see,
yet again, that Quill states a fix for the stability and trimming
issues that plagued the F.21 in 1944 was known about (enlarged tail
surfaces), but production issues ruled it out until 1945. Take the
MAP monkey off Supermarine's back, demanding production at the expense
of development all the time, and this and a lot of other relevant
problems could have been dealt with earlier.

Now, it may just be a question of him
not thinking to mention it, or the way he worded it, but he maentions no such
disagreement between himself and A&AEE regarding the handling of the rear fuselage
tank-equipped a/c; he just says that the handling wasn't acceptable for a long time,
and required a lot of development.

The origin of the "acceptability" comments over the rear-tank tests
appears to be Supermarine's development testing. Aircraft would only
go to A&AEE after they had arrived at what they saw as a production
standard (e.g. Quill testing the 75 gall RF tank in July 1944, but
Boscombe Down not getting it for another six months). Also, note that
the A&AEE testing was not a peacetime acceptance test as such - the
aircraft and fittings involved were often ordered into production
anyway to minimise delays to production totals, and A&AEE testing was
often being performed as representative of current or imminent
production. F.21's were actually being produced before and after
A&AEE first critically reported on them.

I'm certainly not going to claim, based on such flimsy evidence, that this is
definitive proof that the a/c couldn't have been flown in operations with an aft tank
with accceptable handling much earlier given sufficient motivation, especially given
your comments re the prevailing attitude of the A&AEE. But I do think it at least
suggests that the Cg problems were real and agreed to be so by both the A&AEE _and_
Quill. And that's as far as I'm prepared to gaze into my crystal ball. Your reading
may well be different.

And it is, I'm afraid. A&AEE seem to get their first rear-tank Spit
in January 1945, and quantify it as acceptable once 34 gallons out of
the 75 were used. Nobody was going to Boscombe Down and pushing this
idea, the whole issue seems to come from Supermarine. Posit a burning
interest in the Air Ministry in increasing inernal tankage in 1943
(e.g. ACM Kramer getting upset) and I suspect things would have been
remarkably different.

I suggest
with the equivalent of Eaker, Spaatz and Arnold lighting fires under
people's arses to increase range in 1943, this would have happened
earlier.

Not Eaker or Spaatz; it was Arnold through Giles. From "To Command the Sky":

I stand corrected.

As to someone lighting fires for the R.A.F., that was what Pete and I were
postulating, only for the Spit IX/VIII, with the highest priority to getting increased
range British fighters in the U.K. soonest, with all other Spit improvements pushed
back. Grabbing available Mk. VIIIs first (the MTO and CBI/PTO will just have to suck
it up for a while), at the cost of MK.XII/XIV production,

It wouldn't have been at the expense of Mk XII or XIV production if
you're specifying a start after Schweinfurt II in October 1943. The
XII production run had finished, the XIV was settled month beforehand
and was going to start to appear in a dribble in December 1943 as
production deliveries of Griffon 65s began.

then either expanding Mk.
VIII production at the cost of the Mk. IX

That would have been possible, but only at the point of converting
Castle Bromwich over to the VIII in the summer or autumn of 1943.
This needs a demonstration of the effectiveness and need for it
somewhat earlier: hence my LR Vs in 12 Group in July.

or (if possible) transitioning to Mk. IXs
with the extra leading edge tanks of the VIII, with aft fuselage tanks and whatever
airframe mods required to pack usable _combat_ fuel in.

That would have required prducing the VIII wings & airframe, I
believe, rather than stuffing a Merlin 60-series into a Vc airframe as
was done to churn out IXs. So I think there would be production
infrastructure issues. As it was, the Supermarine production group
around Eastleigh delivered about 90 Mk VIIIs to the RAF in July 1943,
which should be enough to prove the concept if you grab them all.

Sure, and that with an aft tank was next on the agenda after boosting production of
the standard Mk. VIII/leading-edge tank Mk. IX. Either of the latter should have given
us an escort radius of 250-300 miles.

See my note on the actual forward-tank capacity of most VIIIs.
Although this may have been changeable.

Unfortunately, a similar chart for a Mk. V doesn't seem to be available on the site,
but I have my doubts that the Mk. V was carrying around any such ballast in 1943, or
if it did, so far aft. Of course, AB197 was a very early Spit IX (the report date
seems to be June 10th, 1942), so that ballast was probably reduced as more operational
equipment was added, but it at least suggests (combined with the Mk. V's further aft
Cg vs.the Mk. IX as reported in various tests on the site) that the Mk. V was pretty
much at the limit, while the Mk. IX had considerably more Cg range available.

I can't find anything to substantiate this with the V myself, and I
understand the validity of your reservations. Nevertheless, the
critical issue as I see it is whether any rear tankage could become
available given improvements in the CoG by means of the enlarged
elevator horn balance and convex Westland elevator. I fully accept
this would, in all probability, have been insufficient to allow a 75
gallon rear-fuselage tank to be carried and cleared for combat. The
critical issue is whether this would have been enough to permit a
rear-fuselage tank to be used in the early stages of flight to extend
the pre-combat range. Given that this was done with a 29 gallon rear
tank, I think there is a useable margin, albeit a smaller one than a
LR-fitted Mk VIII with better weight distrubution and enlarged tail
surfaces would have.

I'm focusing on using the V not because it had more or even
comparitive utility with the Alacal/Stickney LR Mk VIII (something
I've argued for in the past myself), but because even with the greater
constraints involved, it was a more likely concept-demonstrator in the
historical timescale. If you want an overnight conversion to LR Spit
IXs at any given point without the example of a LR operational trial
in the RAF to start with, you'd have to posit the removal of most of
the higher command and their staff involved to eliminate their
existing preconceptions and prejudices.

So this is why I think LR Vs would be an issue worth consideration
even taking into account their inferiority from all aspects of the job
when compared to the VIII. I think it's more credible to posit
changes in the Vs proving the concept, as this would be more
institutionally tolerable. This is important from my point of view,
as I think any counter-factual speculation has to be made within the
known constraints of the industrial, economic and institutional
context to remain credible.

[production pressures]

I don't underestimate the pressures, I just think (as you mentioned a few paragraphs
above) that if the decision had been made to go over to daylight, fighter range
extension would have increased in priority and changes would have to have been
accepted, whatever the disruption elsewhere. Because otherwise, it wasn't going to
work.

Indeed, but when the RAF actually faced this dilemma, at the end of
1939 and then again in spring 1941, they abandoned daylight bombing.
The two concepts had become divorced, for understandable external
reasons, and asserting a sudden and complete reversal of this is
stretching the credibiluity of the institutional appreciation involved
in the speculation.

Now I think the concept is possible, and a valid piece of historical
speculation, but I also think it has to work within the context
involved, and, frankly, anybody demanding a reduction in Spitfire
production in favour of speculative operational development was on a
losing wicket. The British strategical position in this respect can't
be overstressed too much: the USAAF had a doctine and institutional
ambition towards independence which was served by the 8th AF campaign,
secured by other forces doing things like protecting their bases and
dealing with the existing war against Germany. They had room to stop
and rethink tactics and strategy, and change production priorities
accordingly.

The British did not have this space. They had to maintain existing
commitments and fight the war as it existed from a smaller industrial
and economic base closer to the enemy threat. Proving strategic
concepts, even ones which had great war-winning potential, was a
luxury that could not come at the expense of the means for repelling
the enemy in the meantime.

The RAF could not prejudice production of their main fighter when it
was needed for home defence, operations in the MTO and Far East and
supply to the Russians. The difference between these commitments and
facilitating daylight strategic bombing was the difference between
fighting the war and demonstrating an abstract concept. Whatever
happened in the skies over Germany, Fighter Command were conceiveably
in a position to lose a war for national survival. The 8th AF wasn't.
No lack of respect intended. The 8th might prove vital in winning the
war, but high Spitfire production was known to be needed meanwhile to
avoid defeat and stay in the war, which was an essential prerequisite.

The Mk XIV was settled long before production started in October 1943,
the number of airframe's you'd be losing in that year (six for
development work most of which didn't need massive work for Mk XIV
testing and ended up testing contra-props instead, maybe 20 for
delivery to operational squadrons) is trivial. Simply cutting out the
Mk VIII airframe allocation to the Mk XII production might free twice
as many as that.

And we'll be happy to take them, and we'll just have to accept the occasional FW-190
Jabo getting through.

They weren't much of a threat on the larger scale, but if you're
assuming a change of events in autumn 1943, the XII production run is
effectively already over and done with.

But we'll also take the airframes that became 610 Squadron's
Mk. XIVs in January 1944.

If you've got CBAF producing VIIIs or LR IXs in January 1944, which is
perfectly possible if you start in July or August 1943, there's no
shortage of airframes. Also, bear in mind production factor I've
pointed out earlier - it's likely you'll have more airframes than rear
tanks available by the end of 1943, so you might as well do something
to enhance the remaining non-rear-tanked airframes. I really don't
see either Griffon Spit (XII and XIV) having a substantive impact on
LR Spit VIII supply in late '43 - early '44. I do think that the F.21
and later Seafires would have been delayed if Supermarine were working
like demons on rear-tank stability problems in autumn 1943, though.
But as I've already said, small loss.

If we're talking about an operational need in the summer of 1943,

No, the postulated date of the decision (to go over to days) was sometime in the fall
of '43, although the exact date was a bit unclear. It seemed to be in the
September/October timeframe, but we were unable to get ACM Kramer to be more precise.

Well, pending a decision from "Butch" Kramer, let's assume either the
first or second Schweinfurts as the PoD for this speculation. The
faster the better, as far as the Controller of Research and
Development and the MAP production executive are concerned: getting
Castle Bromwich to produce Mk VIII wings and getting Boulton Paul to
do the pressurised, self-sealing tanks are the major bottlenecks in
the short term.

Good points, and I don't disagree about the utility of the Mk. V as 'certainly better
than nothing,' and better to lose people one at a time rather 7 or 8 at a time Again,
my main concern with the V is whether they could in fact have been given the radius
(not range).

I appreciate the distinction, but I think increasing range was the
first, and most easily achieveable step.

I don't think the early XVIs actually had the rear-fuselage tankage
when they first came off the production lines (September 1944),

Right, I should have said the rear fuselage tank (and I think they only came in with
the cut-down rear fuselage) about 16-18 months early, as i forget just when those
versions came out, but I think it was only in '45.

That's right. But while I'm always sceptical about blanket
counter-factual claims about the relative ease of any one measure
changing things, I have to say I can't see any overpowering practical
reasons why they couldn't have arrived sooner, once the institutional
prejudices and conflicting strategic alignments have been addressed.
And I honestly think they are addressable.

Please desist from this moderate rationality or I will complain to
your ISP.

Did I mention that I have INCONTROVERTIBLE PROOF that the U.K. government has been
testing UFOs ( and dissecting ALIEN CORPSES) at their base at Machrihanish,

Nah, you're just confusing Alien corpses with the average westie.
Understandable mistake. We only retain them to give the midges a
round-the-year locally-available food supply until the German tourists
appear in the summer.

cleverly
disguising test flights of same as those by Aurora and, in times past, SR-71s? Wait,
I hear the black helicopters coming to get me. I can feel the beams as they try to
alter my brain. Excuse me while I done my tinfoil hat.

Interesting theory, although it lacks credibility, until we
acknowledge the critical role played by the Templars and the
Illuminatii in the Ministry of Aircraft Production in 1942 [censored]

Gavin Bailey
--

Another user rings. "I need more space" he says.
"Well, why not move to Texas?", I ask. - The ******* Operator From Hell