On Mon, 09 Jun 2014 05:15:32 +0100, Phil W Lee
wrote:

John B. considered Fri, 06 Jun 2014
07:24:04 +0700 the perfect time to write:

On Thu, 05 Jun 2014 06:38:42 +0100, Phil W Lee
wrote:

John B. considered Wed, 04 Jun 2014
08:49:14 +0700 the perfect time to write:

On Tue, 03 Jun 2014 04:25:16 +0100, Phil W Lee
wrote:

John B. considered Wed, 28 May 2014
07:57:25 +0700 the perfect time to write:

On Tue, 27 May 2014 01:39:34 +0100, Phil W Lee
wrote:

Snipped

No, they weren't.
No Vulcan had ever been flown at that total weight before, ever.
And since so much fuel is normally burned in takeoff and climb, and
the Vulcan had never had a properly functioning in-flight refueling
system, the cruise consumption had never been established at anything
even close to that weight, only at max takeoff weight minus takeoff
and climb fuel burn, which is considerably lower.

No Vulcan had EVER flown with a 21,000lb bomb load and full fuel tanks
(and a Dash-10 Radar jamming pod - another addition made purely for
the Black Back missions) until 31st April 1982, the date of the first
Black Buck raid (well, it was about 4 am on the 1st of May when they
hit their target).

While I don't doubt your statement it does seem strange that fuel
consumption versus gross weight tests were not flown during the
initial testing of the aircraft so that at least an educated guess
could have been made about what the effects of a 10 ton bomb load and
a heavy fuel load would be.

The initial testing was done with the original and less powerful
engines, and the aircraft was always intended to be a nuclear
deterrent, not a conventional bomber (so a lower payload).
And the first attempt at in-flight refueling was abandoned because in
all the early testing it proved to be unreasonably difficult to keep a
Vulcan close enough to it's tanker without loss of stability in the
wake turbulence - which is why it was removed.
I'm not sure what changed to make it possible, other than a pressing
need which changed the risk/benefit ratio. Maybe the Victors were
modified to be able to use longer hoses in later developments, giving
more separation between aircraft.

It was converted in the course of the few weeks immediately before the
raid to carry conventional 1,000lb bombs, accept the Dash-10 jamming
pod, and to have it's in-flight refueling reactivated (most of the
internal pipework and probe had been removed and the hole in the
fuselage plugged with epoxy - which had to be carefully drilled out).

And there was never any comparable aircraft type to derive data from -
the "tin triangle" was and is unique in it's configuration - and so
the discovery that it's fuel consumption rose quite so steeply with
that last few thousand pounds of gross weight could not have been
easily predicted except by test flying in that configuration, which
was not something that there was time to do under the circumstances.
They'd only refueled a Vulcan from a Victor successfully within the
previous two weeks (after a desperate race to reinstate the in-flight
refueling system), so the crews were only just qualified for the task
in time. Conducting test flights to establish precise fuel burn rates
was simply never considered - they just projected from what data they
had, which seemed perfectly reasonable at the time.

I can't comment on British practice but I was in the U.S.A.F. F-111b
test program and fuel consumption use versus various gross loadings as
well as various external configurations was flown so at least an
educated guess of what will be the effect of adding some new device
could be made.

And I bet that the actual effect was not the same as the educated
guess every time, was it?

I don't know whether it was or not.

But the aircraft was tested with clean wings, bare pylons, internal
load, external load, combination load and they even tested every
weapon in the inventory that might be carried in the aircraft. And
when they dropped the dummy weapons even the "shapes" were
instrumented so that the weapon drop path could be accurately
calculated. Even the Bombay mounted 20 mm gatling gun was test fired
(it blew the bomb doors off the first time :-)

So you should be capable of understanding that although the fuel burn
for takeoff and climbout (starting at MTOW) was well established, the
fuel burn in the cruise at MTOW was a complete unknown, particularly
with pylons added to the aircraft for the jamming pod (the hardpoint
in the wings had been included in anticipation of a standoff missile
that never actually materialised) so the aircraft had never flown with
even a pylon, never mind any external stores at all).


That wasn't my point. I was arguing against the (apparently) supposed
concept - which I might add that the Wiki account of the initial Black
Buck operation certainly encourages, that the RAF was too stupid to
understand the effects of flying an aircraft with a maximum gross
weight at altitude. I contend that they weren't and did understand the
effects.


The Vulcan was never really intended to be a multi-role aircraft, but
a single purpose delivery vehicle for an H bomb (with an option for
the stand-off missile which as already mentioned, was never
developed), so there was no reason to test a wide variety of
configurations, and as in-flight refueling had never previously worked
properly (even though it had been attempted many years previously), no
reason to test for fuel burn in the cruise at any weight greater than
MTOW-(takeoff+climbout).
So it was well off the top of the graph which was the only reference
available.

A direct quote from "Vulcan 607":

"The Victor planners knew the capabilities of their aircraft inside
out. They needed watertight information from someone with comparable
knowledge of the Vulcan. So they asked Monty: "What do you expect the
Vulcan fuel consumption to be?" Monty and Bill Perrins got to work.
Using the new photocopier, they copied and enlarged the fuel graphs
from the Vulcan Operating Data Manual. The big delta's normal maximum
take-off weight was 204,000lb.
With full tanks, the bombs and the Dash 10 pod, the weight was going
to be a lot higher than that. Off the graph. The ODM simply didn't
include the figure they needed - a Vulcan wasn't supposed to try to
take off at that weight. The curve on the fuel consumption graph they
had was exponential, rather than linear. Monty and his co-pilot tried
to extrapolate a figure from where the curve on the graph ended, and
estimated 13,500lb per hour. They passed this figure on to the Victor
planning team to weave into their refueling plan and wondered why it
had fallen to them to figure it out. What, thought Monty, about the
other resources available at HQ 1 Group?"

They (the supposed experts with all the aircraft data) had actually
been asked, and given the normal figure of 10,000lb per hour - which
is normally correct for MTOW-(take-off+climbout), in the cruise,
averaged over a flight of maximum range with (peacetime) legal
reserves - but they didn't even know what that figure referred to.

The ACTUAL figure comes from another quote from "Vulcan 607":

"Wing Commander Colin Seymour's return to Wideawake provided Jerry
Price and Red Rag Control with a nasty shock - hard evidence of how
much fuel the Vulcan was burning. Half an hour after the four
first-wave Victors had shown how little margin for error there was,
the 55 Squadron boss's figures underlined it. In the thirty-four
minutes between the first and second fuel transfers, 607 had burned
9,200lb of fuel. During that time, the overloaded bombers weight had
never even dropped to its theoretical maximum, let alone below it.
They were flying outside the aircraft's notional limits and the fuel
burn reflected it: 16,250lb an hour. The BLACK BUCK fuel plan was
going to the dogs. But while he could see big trouble ahead, there
was little Price could actually do other than try to be ready for it
when it happened.

Particularly when you make several changes at once.

They didn't make several changes at one time. Every test was
instrumented and usually the instrumentation was changed for every
test. Other than being in the middle of the desert it was a pretty
easy life. Recover the aircraft and than sit around waiting for
Instrumentation to do their job :-)

All very relaxed if you have the time for it.
In the Falklands War, there was under one month from the decision to
re-purpose the Vulcan and Victor as long range conventional bombers
and long range reconnaissance aircraft, re-train all the crews (none
of the Vulcan crew had any in-flight refueling experience at all and
there wasn't a single air-to-air-refueling instructor qualified on the
Vulcan, nor had any of the crews ever dropped an iron bomb) adapt and
convert the aircraft with added pylons (fabricated in the base
workshops out of scrap angle iron, and faired in with fibreglass),
reactivate the in-flight refueling, install conventional bomb racks
(some even rescued from scrapyards) release/fusing panels and wiring,
solve the problems of long-range /accurate/ navigation over a
completely featureless south atlantic and train the navigators
appropriately (which meant adding INS systems cannibalised from some
obsolete VC10s the RAF had sitting around), move the whole fleet of
Victor tankers/ reconnaissance aircraft and the Vulcans to Ascension
Island, create a complete RAF base there under canvas, with planning,
engineering, ordnance, refueling, stores, briefing, intelligence,
communications, medical and accommodation facilities, and plan the
mission.
Just to add to the fun, Wideawake Airfied on Ascension Island only has
a single runway and insufficient parking for the vast fleet of
aircraft which needed to use it.


OK, OK, I accept the fact that the RAF was comprised of many ignorant
people who were quite happy to fly what must have seemed a suicide
mission in support of an inconsequential war, and, again from what I
read, was very inapt at doing it as in seven missions they managed to
get one bomb on the target.

--
Cheers,

Jphn B.