More long-range Spitfires and daylight Bomber Command raids, with added nationalistic abuse (was: #1 Jet of World War II)

In article , Guy Alcala
writes
Alan Minyard wrote:

On Tue, 9 Sep 2003 15:13:14 +0100, Dave Eadsforth
wrote:

In article , John Halliwell
writes
In article , Geoffrey Sinclair
writes
Apparently the outboard sections of the wing were watertight.
Interestingly
the Stirling's wing area was 1,460 square feet, Lancaster 1,297, later
Halifaxes 1,275, B-17 1,420, B-24 1,048 and B-29 1,736.

I'm not disputing the figures above, but I thought the B-24 had a larger
wing area than most contemporary bombers allowing it to fly higher?

Was it not the thick section Davis wing that gave it the improved lift?

Cheers,

Dave

The Davis wing was a high aspect ratio wing with a low angle of
attack.

I'll step with some trepidation into Pete's territory here as he explains this
stuff far better than I do, but we've been keeping him busy doing calcs. The
high
aspect ratio wing provides good L/D ratios, increasing range performance as
well
as
lift at low angles of attack. Here's how the a/c's aspect ratios stack up,
from
low to high:

Stirling 6.72:1;. B-17, 7.58:1; Halifax (early) 7.81:1; Lancaster 8.02:1;
Halifax
(late) 8.51:1; B-24, 11.55:1; B-29, 11.48:1.

As you can see, the B-24, designed a couple of years later than the British
heavies
and five years or so after the B-17, has a much higher aspect ratio wing, and
the
B-29 follows this practice. The wing area of the B-24 was considerably lower
than
the others, for low drag. Good altitude performance requires some combination
of
low wing-loading (high wing area for weight), engine thrust, and aspect ratio.

While the B-24 had good engine power at altitude and a high aspect ratio, it
also
had high wing-loading compared to its contemporaries (not the B-29). It had
better
altitude performance than the British a/c because of its engine supercharging,
not
its wings. The B-17, with similar supercharging as the B-24 had a higher
combat
and service ceiling, because although it had a moderate aspect ratio wing it
also
had far lower wing-loading, and was able to fly slower. The B-24 cruised
between
10-20 mph IAS faster than the B-17, but then it had to to be comfortable. The
crews hated having to fly in company with B-17s.

It's also easier to make lower aspect ratio wings of the same area stronger for
the
same weight, because the stresses can be spread over a longer (and thicker)
root,
which is one reason why a/c like the Stirling and B-17 have reputations for
being
able to take lots of wing damage and survive, and why a/c like the B-24 had
opposite reps. However, the lower aspect ratio wing requires more area to get
the
same lift at the same AoA, increasing drag.

Guy


Agree with all of the above analysis - and thanks for the useful summary
of aspect ratios; both the B-24 and the B-29 must have glided well...

To enlarge on my 'thick wing section' description, and working from
memory of a book read long ago (which can be fatal), I recall that Davis
conceived of a wing section that was based on a mathematically deformed
circle, which he believed would give a more laminar flow. The thicker,
'teardrop-shaped' aerofoil section that resulted was also very useful
structurally, given that he wanted to combine it with a high aspect
ratio wing.

Of course, any wing section inboard of the engines was going to have its
airflow messed up considerably by a few minor essentials; like engine
nacelles and de-icing boots etc etc, but the wing outboard of the
engines may have performed as Davis believed it should during cruise.

True that the high aspect ratio conferred most of the advantages of L/D
ratio, but perhaps Davis's ideas on the wing section itself should not
be forgotten.

Cheers,

Dave

--
Dave Eadsforth

On Wed, 10 Sep 2003 07:53:32 +0100, Dave Eadsforth
wrote:


Agree with all of the above analysis - and thanks for the useful summary
of aspect ratios; both the B-24 and the B-29 must have glided well...

To enlarge on my 'thick wing section' description, and working from
memory of a book read long ago (which can be fatal), I recall that Davis
conceived of a wing section that was based on a mathematically deformed
circle, which he believed would give a more laminar flow. The thicker,
'teardrop-shaped' aerofoil section that resulted was also very useful
structurally, given that he wanted to combine it with a high aspect
ratio wing.

Of course, any wing section inboard of the engines was going to have its
airflow messed up considerably by a few minor essentials; like engine
nacelles and de-icing boots etc etc, but the wing outboard of the
engines may have performed as Davis believed it should during cruise.

True that the high aspect ratio conferred most of the advantages of L/D
ratio, but perhaps Davis's ideas on the wing section itself should not
be forgotten.

Cheers,

Dave

Thanks. I knew that Davis had designed a laminar flow section, but was
unaware that the section had increased thickness. Interesting stuff.

Al Minyard

Dave Eadsforth wrote:

snip

To enlarge on my 'thick wing section' description, and working from
memory of a book read long ago (which can be fatal), I recall that Davis
conceived of a wing section that was based on a mathematically deformed
circle, which he believed would give a more laminar flow. The thicker,
'teardrop-shaped' aerofoil section that resulted was also very useful
structurally, given that he wanted to combine it with a high aspect
ratio wing.

Of course, any wing section inboard of the engines was going to have its
airflow messed up considerably by a few minor essentials; like engine
nacelles and de-icing boots etc etc, but the wing outboard of the
engines may have performed as Davis believed it should during cruise.

snip

He was quite irritated that Consolidated didn't provide full covers for the main
gear wheel wells, as he felt that defeated much of the drag reduction.

Guy

In article , Guy Alcala
writes
Dave Eadsforth wrote:

snip

To enlarge on my 'thick wing section' description, and working from
memory of a book read long ago (which can be fatal), I recall that Davis
conceived of a wing section that was based on a mathematically deformed
circle, which he believed would give a more laminar flow. The thicker,
'teardrop-shaped' aerofoil section that resulted was also very useful
structurally, given that he wanted to combine it with a high aspect
ratio wing.

Of course, any wing section inboard of the engines was going to have its
airflow messed up considerably by a few minor essentials; like engine
nacelles and de-icing boots etc etc, but the wing outboard of the
engines may have performed as Davis believed it should during cruise.

snip

He was quite irritated that Consolidated didn't provide full covers for the
main
gear wheel wells, as he felt that defeated much of the drag reduction.

Guy

Some penny-pinching accountant at work perhaps?

I was always mystified by the fact that the Spitfire didn't get full
wheel-well covers until late in the war - they went to all that trouble
gluing split peas all over the wing to optimise the placement of flush
and round headed rivets and missed out on some thing that seems even
more obvious (unless the drag from the wheel well really was
inconsequential up to speeds of 400 mph or so - but that seems a bit
counter instinctive).

Cheers,

Dave

--
Dave Eadsforth

In article , Dave Eadsforth
writes
Some penny-pinching accountant at work perhaps?

I was always mystified by the fact that the Spitfire didn't get full
wheel-well covers until late in the war - they went to all that trouble
gluing split peas all over the wing to optimise the placement of flush
and round headed rivets and missed out on some thing that seems even
more obvious (unless the drag from the wheel well really was
inconsequential up to speeds of 400 mph or so - but that seems a bit
counter instinctive).

I think originally it simplified the gear retraction 'hydraulics'. The
first Spits had a hand pump to retract the gear, which required IIRC 27
pumps to fully retract it. I guess the full wheel well covers probably
came along with the retractable tail wheel (possibly more important?) as
well?

--
John

John Halliwell wrote:

In article , Dave Eadsforth
writes
Some penny-pinching accountant at work perhaps?

I was always mystified by the fact that the Spitfire didn't get full
wheel-well covers until late in the war - they went to all that trouble
gluing split peas all over the wing to optimise the placement of flush
and round headed rivets and missed out on some thing that seems even
more obvious (unless the drag from the wheel well really was
inconsequential up to speeds of 400 mph or so - but that seems a bit
counter instinctive).

I think originally it simplified the gear retraction 'hydraulics'. The
first Spits had a hand pump to retract the gear, which required IIRC 27
pumps to fully retract it. I guess the full wheel well covers probably
came along with the retractable tail wheel (possibly more important?) as
well?

No, they were removed to simplify things at RAF suggestion in spec. F.16/36,
dated 28 July 1936, which entailed the changes to be made from the
prototype. F.16/36 was the spec for the first production contract (on 3
June 1936) for 310 a/c, which lists thirty-three seperate paragraphs, each
entailing one change:

Para xxi: "Provided no reduction in the performance will be entailed, the
hinged flaps on the wheels may be replaced by fixed flaps which, when
retracted, will not cover the wing apertures completely." Presumably no
significant reduction in performance resulted, at least not at the speed the
a/c was then capable of attaining.

Guy

In article , Guy Alcala
writes
John Halliwell wrote:

In article , Dave Eadsforth
writes
Some penny-pinching accountant at work perhaps?

I was always mystified by the fact that the Spitfire didn't get full
wheel-well covers until late in the war - they went to all that trouble
gluing split peas all over the wing to optimise the placement of flush
and round headed rivets and missed out on some thing that seems even
more obvious (unless the drag from the wheel well really was
inconsequential up to speeds of 400 mph or so - but that seems a bit
counter instinctive).

I think originally it simplified the gear retraction 'hydraulics'. The
first Spits had a hand pump to retract the gear, which required IIRC 27
pumps to fully retract it. I guess the full wheel well covers probably
came along with the retractable tail wheel (possibly more important?) as
well?

No, they were removed to simplify things at RAF suggestion in spec. F.16/36,
dated 28 July 1936, which entailed the changes to be made from the
prototype. F.16/36 was the spec for the first production contract (on 3
June 1936) for 310 a/c, which lists thirty-three seperate paragraphs, each
entailing one change:

Para xxi: "Provided no reduction in the performance will be entailed, the
hinged flaps on the wheels may be replaced by fixed flaps which, when
retracted, will not cover the wing apertures completely." Presumably no
significant reduction in performance resulted, at least not at the speed the
a/c was then capable of attaining.

Guy


Thanks for that quote - ends a long-standing mystery!

Perhaps they should have stuck with that nice streamlined tailskid...

Cheers,

Dave

--
Dave Eadsforth

Dave Eadsforth wrote:

In article , Guy Alcala
writes
John Halliwell wrote:

In article , Dave Eadsforth
writes
Some penny-pinching accountant at work perhaps?

I was always mystified by the fact that the Spitfire didn't get full
wheel-well covers until late in the war - they went to all that trouble
gluing split peas all over the wing to optimise the placement of flush
and round headed rivets and missed out on some thing that seems even
more obvious (unless the drag from the wheel well really was
inconsequential up to speeds of 400 mph or so - but that seems a bit
counter instinctive).

I think originally it simplified the gear retraction 'hydraulics'. The
first Spits had a hand pump to retract the gear, which required IIRC 27
pumps to fully retract it. I guess the full wheel well covers probably
came along with the retractable tail wheel (possibly more important?) as
well?

No, they were removed to simplify things at RAF suggestion in spec. F.16/36,
dated 28 July 1936, which entailed the changes to be made from the
prototype. F.16/36 was the spec for the first production contract (on 3
June 1936) for 310 a/c, which lists thirty-three seperate paragraphs, each
entailing one change:

Para xxi: "Provided no reduction in the performance will be entailed, the
hinged flaps on the wheels may be replaced by fixed flaps which, when
retracted, will not cover the wing apertures completely." Presumably no
significant reduction in performance resulted, at least not at the speed the
a/c was then capable of attaining.

Guy


Thanks for that quote - ends a long-standing mystery!

Perhaps they should have stuck with that nice streamlined tailskid...

I just last night got in Price's "The Spitfire Story" at my library, which I
devoured immediately. Aside from confirming the above (that there was no
noticeable change in performance with the wheel flaps removed from the
prototype), he also says that Mitchell wanted to stick with the tailskid, but the
Air Ministry insisted on the tailwheel, because they knew (but couldn't tell
Mitchell at the time, because it was classified) that they were going to lay down
all-weather (i.e. paved) runways at all the fighter bases, and the tail skid
wouldn't last long under those conditions. This thing's just filled with great
info.

Guy