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It's happening! Um... sort of.



 
 
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  #381  
Old June 6th 14, 01:24 AM posted to rec.bicycles.tech
John B.
external usenet poster
 
Posts: 145
Default It's happening! Um... sort of.

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:

Frank Krygowski considered Sun, 25 May 2014
22:51:30 -0400 the perfect time to write:


The problem is that the exact fuel burn curve is different for every
airframe and engine combination, and the Vulcan had not had any
in-flight refueling capability since it's earliest days - and when it
DID have it, it was intended to be used in combination with a single,
high yield bomb or missile, of relatively light weight, where even
brim-full tanks would give something like 8 or 9 tons lower gross
weight, and with the earlier, slightly less powerful (and more
economical) engines, not the Olympus 301s as fitted to all of the


But the fuel use to gross weight equation is common to all aircraft
and the Vulcan people must have know about it. After all a jet burns a
vast amount of fuel just to get off the ground and to cruising
altitude - which admittedly combines gross weight and operation in
denser air, but still...


You've just demonstrated how little you know about aerodynamics.
The equation may be the same, but the variables that you have to plug
into it are different (as already noted, for each airframe and engine
fitment) - and they didn't have them.


Stop being ridiculous. I said that the equation is common to all
aircraft not the details. But if you say that the RAF flew the
aircraft from 1956 when they apparently entered service until 1984
when they flew to the Falklands without ever considering the fuel
use/weight characteristics of the aircraft, I can only say that the
RAF must have gone down hill at a remarkable rate since the Big War
ended.

All the had were the (fairly coarse) graphs in the operations manual,
which didn't go high enough. And the pocket calculator wasn't up to
the job of extrapolating from them without the formulae from which
they were derived.

So not only was there no current data on what the fuel consumption at
that loading would be, there never had been any.


Perhaps not but certainly the effects of full fuel loads combined with
large bomb loads must have been known.


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.


Slow down there. The RAF must have known what fuel consumption was for
a max gross take off and climb to altitude as that is probably the
most critical portion of an aircraft flight plan as it takes a
considerable portion of the fuel load just to get off the ground and
get to altitude.

And I can't believe that there weren't air density or pressure tables
to correlate that information. Twenty years before the Falkland flight
those figures were in common use even for ground grunts. I can
remember calculating temperature, vapor pressure and pressure altitude
to calculate the horsepower output for a recip engine. The charts were
even printed in the maintenance manual.

The British bombers in WW II made some pretty long flights and I can't
believe that fuel management was a mystery to them.

Remainder snipped
--
Cheers,

John B.
(invalid to gmail)
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  #382  
Old June 6th 14, 01:24 AM posted to rec.bicycles.tech
John B.
external usenet poster
 
Posts: 145
Default It's happening! Um... sort of.

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 :-)

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 :-)

That is, after all, why you do testing.
In the case of Black Buck, they simply didn't have the time, and
relied (wrongly, as it turned out) on the educated guess.
Later missions modified the fuel plan, so that the Vulcan was flying
most of the way with a lighter fuel load, only filling right up for
the last run-in to target.

The testing time was so short that they rigged a jump-seat for an
in-flight refueling instructor to ride along on the raid, as the
pilots had so little experience of it, and the risk of them being
unable to tank in unknown weather was deemed to be too high a risk to
take.
In the words of Bob Tuxford AFC (the captain of the (reserve)
long-shot final tanker:
"We were flying in towering cumulous clouds, at night, your visual
references for formating on the aircraft in front are reduced,
therefore with the turbulence, the distracting lightning, St Elmo's
Fire all around the cockpit windows, the whole process of achieving a
stable contact and maintaining it for long enough to get the fuel on
becomes much more difficult."


But this wasn't a new discovery, for God's sake. The U.S. had been
flying in air refueling, since 1948 - 49, 30 years before Black Buck
and the British had known about it since Cobham plc. was formed in
1934 as " Flight Refueling Limited".


In-flight refueling is about the most demanding task required of any
pilot, and NONE of the pilots qualified for Vulcan bombers had any
experience of it at all (as it wasn't relevant for the type) until
less than 2 weeks before the mission was flown.
In the same time frame, they had to learn bombing with conventional
weapons (remember, the Vulcan was only ever intended to be a delivery
vehicle for a nuclear deterrent, where anything within half a mile is
a hit). Not one Vulcan crew had ever dropped an actual iron bomb
before, although they were all proficient in the "idiot's loop"
manoeuvre for delivering an H bomb. But that's a whole different
game.

In fact Bob Tuxford had to exchange roles with the other Victor on the
final outbound leg of BB1, as they'd broken their refueling probe
taking fuel from his Victor, which meant he could only take fuel from
the other Victor, not give it to them, and.the fourth completed
mission (BB6 - 3 & 4 were scrubbed) had to divert to Brazil for
internment, owing to breaking it's refueling probe during it's
recovery tanking.

Breaking a probe is not something unique to the British use of the
system. The U.S. has broken a number also :-)


Well, of course - the probe is designed to be the weak link, and fail
before anything else does or either aircraft is destabilised.

But at that time the only tanker in the world capable of acting as
both receiver and donor was the Victor.
Without the ability to swap roles seamlessly with other tankers in the
fleet, that broken probe would have aborted the mission (and the
mission would not have been possible at all anyway).
That flexibility meant that only damage to the probe on the Vulcan
could not be accommodated by role-swaps within the fleet.
I understand that lessons from that have been adopted by the US since
then, in making their own tankers dual role capable.

It should be noted that the Black Buck raids are still the longest
bombing missions ever conducted from a single fixed base - longer
missions conducted since have all had the benefit of forward
positioned tankers, and some have not even returned to their base of
origin. So it's not all that surprising that it was something of a
learning experience for all concerned.
The important thing is that they knew it was a learning experience, so
noted the fuel remaining in the returning Tanker fleet was below
expected reserves (well, what are reserves for?), did the sums, and
knew to launch additional recovery tankers.
So it worked, but it took 18 sorties by 12 tankers to get 1 Vulcan
over the target, where they were expecting 16 sorties. by the same 12
tankers.

There is a lot of information on-line about the raids, as well as in
the book "Vulcan 607" by Rowland White, but you can't beat speaking
directly to those involved.


Not to demean the action as it set a record for long range bombing
flights but I very much doubt that the level of ignorance in the RAF
was as high as seems to be claimed. My guess was that the mission
planners had a very good idea of how much weight could be carried at
what gross load and planned the mission accordingly as well the
approximate drag of any added devices. After all the first attempt was
successful.


You are calling the crews involved liars.
The fact that Bob Tuxford (the tanker pilot) was awarded the Air Force
Cross for his action in giving up his own fuel to the Vulcan, and
risking his own aircraft's safe return, shows that it was well outside
the expected mission parameters..

Do you think that all those who recommended him, considered the
recommendation, and approved it were idiots?


Given that I have recommended two blokes for medals and had the
recommendation turned down on what I thought was a rather far out
technicality I suspect that at least some of the people in the
approval chain may be a bit off

They would have all had access to the actual data from the mission.
No decorations were awarded to the crews of any but Black Buck 1,
because they didn't have to take the same risks to get the job done.

The wiki report mentions 7 BB missions and while several had aircraft
problems only the first seemed to have had fuel problems.


Well, that's called learning from experience.
Call BB1 the test flight if you like - in many ways, it was.
As they say, no plan survives first contact with the enemy.

And the much
mentioned account of adding a chemical toilet... I worked on the B-29
and B-50's and their chemical toilet" weighed all of, say 10 lbs. :-)
Hardly worth mentioning when one is hauling around 10 tons of bombs.

You clearly don't know how cramped the crew compartment of a Vulcan
is.
Adding an extra crew member and a chemical toilet was a considerable
achievement.
I suppose they could have saved a bit of space by putting the extra
crew member on the chemical toilet!
Not that it makes any measurable difference to the fuel burn, of
course.

I must admit that in-light refueling is a scary enough concept for me
as a private pilot in the first place (Deliberatly arranging a mid-air
collision seems crazy enough to me, even before pumping fuel through
the point of contact), without trying to do it in a thunderstorm with
St. Elmo's Fire all over the plane, knowing that when you break
connection there WILL be a brief leakage of jet fuel as the valves
shut off (bad enough on the Victor/Vulcan combination that it obscured
visibility through the windshield, and even on one occasion flamed out
an engine).


I believe that the Vulcan used the old probe and drogue system which
is much more laid back then the modern system of flying up close...
real close, to another airplane and being stabbed in the nose :-)

But listening to the crews, many attempts at refueling are not
successful and apparently it is not unusual for the receiver have to
make several tries before he gets a full load. Again from listening to
the crews it appears that the biggest problem is the rapid weight
transfer to the receiver. There you are sitting there all trimmed up
and motionless compared to the Tanker; and someone dumps several
thousand pounds of fuel into you :-(

--
Cheers,

John B.
(invalid to gmail)
  #383  
Old June 10th 14, 01:09 AM posted to rec.bicycles.tech
john B.
external usenet poster
 
Posts: 2,603
Default It's happening! Um... sort of.

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.
  #384  
Old June 13th 14, 12:33 AM posted to rec.bicycles.tech
john B.
external usenet poster
 
Posts: 2,603
Default It's happening! Um... sort of.

On Thu, 12 Jun 2014 01:48:37 +0100, Phil W Lee
wrote:

John B. considered Tue, 10 Jun 2014 07:09:26
+0700 the perfect time to write:

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.

Oh, they certainly understood the concepts, but had never had to apply
them to that aircraft. And the Vulcan, as it turns out, increases
it's fuel burn very steeply just above the point where the graph in
the operating manual reaches.
It's a matter of having to supply the extra lift by increasing the
angle of attack, and the huge area of that vast delta wing being
overexposed to the airflow with a steeper than designed nose-up
attitude. The same effect is used on landing, to allow the Vulcan to
operate off the same length runways as the Victor without using a
braking parachute - they just keep the nose high for much longer in
the roll-out, and use it as a massive air-brake. The Victor doesn't
have anything like the wing area, so proportionately less aerodynamic
braking available, despite the clamshell airbrake in the tail, hence
it needing a 'chute where the Vulcan doesn't.

The other problem was that they'd never operated Victor and Vulcan
together as a formation over any distance - and the best economy
cruise speeds are somewhat incompatible. The formation speed was
therefore a compromise which raised fuel consumption on both.
This was not as significant as the problem of operating continually at
loads which were over (peacetime) maximum gross weight on the Vulcan
though.
Later missions dealt with both problems by not flying as a single
formation and not overloading the Vulcan, reducing overall fuel burn
considerably.
And the wiki article is not a particularly good source on those
missions (as you say, where the chemikhasi is barely mentioned in
"Vulcan 607" it seems to have been an object of much fascination for
the Wiki author, despite there being many other additions of far
greater significance).

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.


It only needed one on the runway, and anyone would have been ignorant
of the performance and fuel burn when using an ancient aircraft for a
purpose it was never intended to fulfil.
Of course, considerable other damage was caused around the airfield by
the bombs which hit elsewhere than on the runway, and the plan was
never to do more than cut it - which they did on the first mission.
All the subsequent missions had different objectives.
But it was a mixture of ingenuity, bravery, hard work, and very
careful planning that they succeeded.
As for inconsequential, it was the cause of the eventual downfall of
the military dictatorship in Argentina, so I doubt the relatives of
all the disappeared would agree with you.

I recommend you read the book which I've already referred to, and
which I have not found any major inaccuracies in.
It's available in Epub, Kindle, .pdf dead tree, and possibly other
formats.


I've pretty much given up reading war stories. In a couple of cases I
was there, or knew someone that was there, and strangely the events I
remember, or the other guy remembered, aren't the same thing written
in the book. But as they say, history is written by the winners.
--
Cheers,

Jphn B.
 




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