In article ,
(The Revolution Will Not Be Televised) writes:
On Wed, 20 Aug 2003 02:04:33 -0400, (Peter
Stickney) wrote:

[arbitrarily moved to this thread by me]

I've been delayed my own self, but I'll invite myself back in...

By all means, except I also note a depressing lack of nationalistic
abuse in this post.

Oh, well then, how's this: The last time a Brit tried to hand my
family a line like that we threw his tea in the harbor.


[rear fuselage tanks in Spit Vcs]

The Spit, especially the small tailed Mk V, had a very narrow CG
range. Something on the order of 1.6". The later aircraft, both the
2-stage Merlin powered VIII, IX, and XVIs, and the various Griffon
models, also had a narrow range, but had the advantage of a heavier
engine way up front to even things out. It'a also teh case that
retracting the gear on a Spit translated the CG aft nearly half of its
range. That's teh problem with dainty little airplanes - it doesn't
take much to upset 'em.

OK, but let's be clear about the standard of aircraft modification
involved. Did this include an enlarged elevator horn balance, and if
not how much aftwards CoG movement did bob-weights plus elevator
adaption provide? Quill states that the bob weights gave about 2
inches of rearward travel, and the westland elevator tested at the end
of 1942 gave a "significant amount of C of G travel" with the enlarged
horn balance being "even more effective", although I don't have exact
figures for the CoG movement involved.

That's going to take a lot of fiddly meaduring & figuruing to say for
sure, but, looking over the inboard profiles (X-ray views) of both
aircraft, one thing does stand out - a Spitfire's cockpit is aft of
the wing, and well aft of the CG. And the fuselage ahead of the
cockpit is already full of stuff. (Fuel, mostly) The available space
behind the cockpit is a long way aft of the CG, which isn't good.
A Mustang's cocpit is over the wing. The aft tank location is
basically right at the trailing edge. Not only is the airplane more
tolerant of how it's loaded, the tank location is in a better place.

That might be a reason for the Sutton Harness in a Spit- you wouldn't
want the pilot leaning forward causing the airplane to nose down!
(Actually, I have doen this with light airplaes, to demonstrate the
balance of forces to (captive audience) passengers - lean forward,
nose down, lean back, nose up.)

Other U.S. fighters that I could dig up in short order are the P-40,
with a CG range of 8.9", and the P-63 with a range of 5.4". On first
analysis, stuffing an aft fuel tank into a Spit V is a much more dicey
proposition that doing the same with a P-51.

Agreed, but is this insoluable? The question doesn't appear as easily
to definatively answer (either way) as it first appeared to me.

Well, for teh Mk VIII and Mk XIV, it indeed was. FOr a Mk V, I'm not
sure.

Actually, if you're looking for a fairly long-ranged Medium/Low
altitude escort fighter already in RAF hands in 1942, might I suggest
the Allison-engined Mustang I, IA and II. They're long legged, adn
while they don't climb as well as a normally loaded Spit V, they're
danged fast, accelerate well, and can meet an Fw 190A on fairly equal
terms. Mustang Is were the first RAF fighters over Germany, after teh
fall of France, and they spent a lot of time stooging around in the
same areas that are being proposed as Medium Bomber targets.

Su I've no objection to using them as B-25 escorts, as they
actually were historically, except to expand this usage. I still feel
the altitude limitation and the numbers available leave the LR Spit V
a live issue nonetheless. Even Typhoons got used as 2 Group escorts
on occasion, and in this scenario there's a real attritional premium
to be paid for allowing the Luftwaffe undistracted attention on
daylight Lancaster forces, above and beyond what B-17s suffered, and
as a result I think the "everything and the kitchen sink" approach
would be adopted. The commitment of the available fighter force would
need to be much higher than the RAF historically got away with.

Actually, according to the A&AEE's reports on testing Mustang Is, and
various Mk Vs, I don't see a whole lot of difference in altitude
performance, even without the Mustang II's higher-supercharged engine.
It didn't climb as well as a Spit, adn it didn't quite turn as well,
but it did out-speed, out-turn and out-zoom the Fw 190As that the
Abbeville boys were flying. (Speaking of which, is Holly Hills still
extant? I know he was recovering from his stroke a few years back.)


Perhaps. It's also the case that the RAF were never really in the
Long Range Escort business. Most of their missions didn't require
flying Combat Air Patrols over German airfields near Prague. The aft
fuel tank didn't provide a whole lof of gain for the RAF.

Precisely. We need to posit a sufficient instiutional change of
policy and interest to even begin this, but as nothing would happen
without it, we might as well take it as a given.

Well, I could begin my somewhat-factually based Nationalistic Rant
about how the Brits, and Europeans in general never figured out how to
put long range into fighter airplanes becasue their countries are so
danged small, and that you can't ever be more than an hour from a
National Border or coastline, unlike those of us who need to be able
to fly stuff from San Francisco to Honolulu routinely, but I won't.

Just my opinion, mind, but I think the thing that really would have
crimped an RAF long range day bombing effort would have been pilot
availability. The RAF Night Heavies (Except, I think, for the
Stirling), were 1 pilot airplanes.

They all had facility for 2 pilots, e.g. extra controls could be
fitted to the Halifax and Lanc if neccessary, but basically they had
ceased to be 2-pilot aircraft by 1943.

That's not enough if you expect to
be getting shot at by people wh actually can see what they're shooting
at. You're going to want copilots, and where are you going to get
them? The Empire Air Training Scheme was a tremendous achievement,
but it was pretty stretched supplying the pilots that the RAF needed
in real life. And you'll have to divert even more pilots to be
instructors.

The loading on the training infrastructure would increase, and the
attritionally-supportable force would shrink, but then again BC took
heavy casualties and expanded, and I'm not aware of a critical aircrew
shortage: aircrew training slots seem to be over-subscribed since
1941, with pools of aircrew forming everywhere except in Bomber
Command. The output of trained pilots is an issue, but then I'm not
aware of it being inadequate historically. If anything, the British
prioritised aircrew training too much in the period 1941-43 with
repercussions elsewhere on the war effort (e.g. infantry replacements
in 1944-45).

It's a good question, though. If you suddenly start needing twice as
many bomber pilots, the repercussions will be far & wide.

Again, I must disagree. The cold, hard numbers say that the Spit was
a lot less tolerant of stuffing weight behind the wings. It's
intersting to note that the Wright Field modified Spits got a big
chunk of their extra capacity by stuffing fuel into the wing leading
edges, which not only didn't upset the CG as much, but moved it in the
forward (good) direction, somewhat counterbalancing the tank behind
the cockpit.

Yes, but even the Wright Field Spits also had 43 gallon tanks behind
the pilot, against 33 gallons in the wings (according to the A&AEE
report summary on MK210 in S&M). Wing tanks have always been a given
with me, as you & Guy have already specified Mk VIII airframes, which
had 25 gall leading-edge tanks, but as Quill states, the only
available space for major increases in internal fuel was behind the
pilot.

43 of _whose_ gallons? It's worth pointing out that the Wright Field
modded aircraft used a somewhat smaller tank behind the cockpit, adn
stucl 150 U.S. Gallons of fuel under the wings, where CG wasn't an
issue. I'll admit to being a bit puzzled about why the RAF never went
for wing rack mounted drops on a Spit, until it occurred to me that
there isn't any significant amount of fuel in the wing, and teh
plumbing and pumping is going to be a royal pain.

You have also opened the drop-tank issue a little wider here with the
two 62 gallon underwing tanks carried by MK210, which is also useful
for the discussion. The Vc airframe could well have taken drop tanks
in the under-wing bomb positions: a 44 gallon drop tank under each
wing would give us another 88 galllons to go with a 90 or 45 gallon
slipper tank. Granted, this isn't increasing the combat radius, and
even I'm dubious about the weight issues, but every gallon gives
greater possibilities for deeper penetration escort up to the limit of
the internal fuel only return-to-base range.

See above.

Much less, according to the reports. To increase the CG range of a Mk
V enough to fit a rear tank, you'll need a bigger tail, and ballast in
the nose. At that point, it stops being a Field Conversion, and
starts looking like a remanufacturing job.

This all hinges on the CoG travel the remedial measures like
bob-weights and elevator modification provides. I can't really go any
further until I have some kind of figure to associate with the latter.
I appreciate the rational grounds for your doubts, but I don't think
this issue is resolved yet.

Well, the elevator balance change will add to the stabilizer/elevator
combination area, and that's good. It also will reduce the control
forces for pitch, possibly to the point whre the controls are
over-balanced, and once you start waving the stick around, it wants to
amplify the action, and that's bad, leading to overcontrolling at
beast, and breaking the airplane at worst, especially with an airplane
that's already pretty light on the controls, like a Spit. The
bobweight tends to resist this overbalancing, at a cost in stick
forces. The thing is, the amount of influence from the bobweight
changes, like the elevator balance, with deflection. It's confusing,
adn there's no intuitive answer other than make the tail bigger.
The same applies to the rudder, as well.

If I get a chance, I'll run some numbers for how much fuel it would
take to get a Spit V to its rear limit. At a first guess, I'd say
"Not Much". The rearward shift when the gear comes up is a problem.

Granted. But none of this works without the hierarchy breathing fire
from the CAS on down for long-range escorts a la Arnold. Let me know
what you think could be done with a range of figures, from 4 inches
rearward travel on up, which seems a reasonable conjectural starting
point for me. Don't forget to use the Vc airframe as a reference
rather than a Vb in regard to landing gear.

I'll get round to it, after...

Alternatively, sit out in the sun with a cold beer instead.....

After the Great Blaster Worm and Sobig Hydra chases I've had this
week, that's top priority. (Work real job, than travel up to the
North COuntry to help out some former clients)

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster