Stretching WW2 Designs

Maybe 'cause it's not a WWII design, nor stretched from a WWII design,
& for some reason, folks are trying to keep these posts on topic for
more than a couple of posts.



"James Hart" wrote in message ...
Peter Stickney wrote:
In article ,
(JDupre5762) writes:
I have been wondering why were so few WW2 aircraft designs
"stretched" in order to get more performance or payload? I know of
the FW 190D which was stretched in the aft fuselage section in order
to compensate for the installation of Jumo V 12 engine. Could other
designs have benefitted from the technique of stretching in one way
or another? Was it not done because the designs of the era were not
suited to it? In recent years even reworked C-47s have been
stretched. Was there simply no perceived need to stretch a design?

For "stretch" it's rather hard to beat the Spitfire. I began the war
perfoeming at same level as its main competitors, and through
continual redesign and refinement was still in peak form when the war
ended.
Of course, installed power had more than doubled, the tail was
completely new, the feselage adn wing structure was completely redone,
they reshaped teh fuselage for a bubble canopy, and made a
fighter-bomber (And Carrier-borne Fighter-Bomber to boot) out of it.
Spits stayed in RAF and RN service well after the war. Not too half
bad.

I think that transports didn't get the same treatment for a number of
reasons. Most transport types didn't have options which afforded
greatly increased power, and the load carrying performance of
airplanes at that time was limited by available power more than
anything else - you'd run out of payload weight available before you
ran out of payload volume. Getting more payload required a whole new
airplane. The C-46 was considerable bigger than the C-47 it
supplanted.

That being said, I suppose you could make a case that DOuglas did
start a program of stretching transports with the DC-4-DC-6-DC-7
line.

Speaking of transports, I'm surprised no one's brought up the Herk's recent
50th birthday.

"Peter Stickney" wrote in message
...
In article ,
(JDupre5762) writes:
I have been wondering why were so few WW2 aircraft designs "stretched"
in order
to get more performance or payload? I know of the FW 190D which was
stretched
in the aft fuselage section in order to compensate for the installation
of Jumo
V 12 engine. Could other designs have benefitted from the technique of
stretching in one way or another? Was it not done because the designs
of the
era were not suited to it? In recent years even reworked C-47s have
been
stretched. Was there simply no perceived need to stretch a design?

For "stretch" it's rather hard to beat the Spitfire. I began the war
perfoeming at same level as its main competitors, and through
continual redesign and refinement was still in peak form when the war
ended.
Of course, installed power had more than doubled, the tail was
completely new, the feselage adn wing structure was completely redone,
they reshaped teh fuselage for a bubble canopy, and made a
fighter-bomber (And Carrier-borne Fighter-Bomber to boot) out of it.
Spits stayed in RAF and RN service well after the war. Not too half
bad.

I think that transports didn't get the same treatment for a number of
reasons. Most transport types didn't have options which afforded
greatly increased power, and the load carrying performance of
airplanes at that time was limited by available power more than
anything else - you'd run out of payload weight available before you
ran out of payload volume. Getting more payload required a whole new
airplane. The C-46 was considerable bigger than the C-47 it
supplanted.

That being said, I suppose you could make a case that DOuglas did
start a program of stretching transports with the DC-4-DC-6-DC-7
line.

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

I had originally thought of the Spitfire as a good example of stretching
when this question first came up. However, on reflection, there was very
little airframe stretch during the service life of this type which
contributed to its ability to maintain parity in air combat. Essentially
there were two major airframe changes (Mk.VIII and F.21), and two major
engine ones (2-stage supercharging in Merlin 60's, and introduction of the
Griffon). The basic Mk.I led to the Mk.II, Mk.V, and ultimately the Mk.IX.
The Mk.IX was essentially an interim type allowing use of the series 60
Merlin engine before the definitive Merlin powered Mk.VIII was ready. With
the introduction of the Griffon engine, the definitive Spitfire was to be
the F.21 (and followed by F.22, and F.24). Again, to facilitate early
introduction of the engine upgrade, an interim model was introduced, based
on the Mk.VIII, and called the Mk.XIV.

During the history of the Spitfire, major changes to the airframe were few,
being restricted to accommodating the Griffon engine in the Mk.XII (another
interim model, based on the Mk.V), provision of a cut down rear fuselage to
allow a bubble canopy (Mk.IX and Mk.XVI onwards, although interspersed with
normal canopy), and F.21 onwards (redesigned wing). Other lesser changes
included extended wing tips for high altitude interception (Mk.VII,
Mk.VIII), increased surfaces to horizontal and vertical tail, changes in
armament from 8x 0.303 mgs to 2x 20mm plus 4x 0.303 mgs, 2x 20mm plus 2x
0.50 mgs, and finally 4x 20mm. Invisible changes included additional fuel
cells in the rear fuselage and fuselage strengthening.

But the most significant cause of the Spitfire's extended longevity was the
remarkable work of Ernest Hive's team at Derby in forcing more and more
power from the Merlin engine, and ultimately the successful installation of
the Griffon engine. Without the engineering brilliance of Rolls Royce, the
Spitfire, as a contemporary fighter, would have become obsolescent by
1941-42.

Graham Salt

In article ,
"Graham Salt" writes:

"Peter Stickney" wrote in message
...
In article ,
(JDupre5762) writes:
I have been wondering why were so few WW2 aircraft designs "stretched"
in order
to get more performance or payload? I know of the FW 190D which was
stretched
in the aft fuselage section in order to compensate for the installation
of Jumo
V 12 engine. Could other designs have benefitted from the technique of
stretching in one way or another? Was it not done because the designs
of the
era were not suited to it? In recent years even reworked C-47s have
been
stretched. Was there simply no perceived need to stretch a design?

For "stretch" it's rather hard to beat the Spitfire. I began the war
perfoeming at same level as its main competitors, and through
continual redesign and refinement was still in peak form when the war
ended.
Of course, installed power had more than doubled, the tail was
completely new, the feselage adn wing structure was completely redone,
they reshaped teh fuselage for a bubble canopy, and made a
fighter-bomber (And Carrier-borne Fighter-Bomber to boot) out of it.
Spits stayed in RAF and RN service well after the war. Not too half
bad.

I think that transports didn't get the same treatment for a number of
reasons. Most transport types didn't have options which afforded
greatly increased power, and the load carrying performance of
airplanes at that time was limited by available power more than
anything else - you'd run out of payload weight available before you
ran out of payload volume. Getting more payload required a whole new
airplane. The C-46 was considerable bigger than the C-47 it
supplanted.

That being said, I suppose you could make a case that DOuglas did
start a program of stretching transports with the DC-4-DC-6-DC-7
line.

I had originally thought of the Spitfire as a good example of stretching
when this question first came up. However, on reflection, there was very
little airframe stretch during the service life of this type which
contributed to its ability to maintain parity in air combat. Essentially
there were two major airframe changes (Mk.VIII and F.21), and two major
engine ones (2-stage supercharging in Merlin 60's, and introduction of the
Griffon). The basic Mk.I led to the Mk.II, Mk.V, and ultimately the Mk.IX.
The Mk.IX was essentially an interim type allowing use of the series 60
Merlin engine before the definitive Merlin powered Mk.VIII was ready. With
the introduction of the Griffon engine, the definitive Spitfire was to be
the F.21 (and followed by F.22, and F.24). Again, to facilitate early
introduction of the engine upgrade, an interim model was introduced, based
on the Mk.VIII, and called the Mk.XIV.

I have to disagree, a bit. (While the basic Spitfire Shape was
retained, the Griffon engined Spits were much different,
structurally. You couldn't make a Mk IX into a Mk XII with a
conversion kit. The wing structure also evolved quite a bit, as
well. (Wasn't the Mk VIII actually based on the Mk III, which was
to be a Merlin XX powered flavor that was abandined in favor of the Mk
V when it was decided that the 2-speed Merlins were better off being
put into Hurricanes? It's Rivet Counting, I know.)


But the most significant cause of the Spitfire's extended longevity was the
remarkable work of Ernest Hive's team at Derby in forcing more and more
power from the Merlin engine, and ultimately the successful installation of
the Griffon engine. Without the engineering brilliance of Rolls Royce, the
Spitfire, as a contemporary fighter, would have become obsolescent by
1941-42.

T'warnt so mach Hives as Stanley Hooker, and his almost mystical
ability to squeeze that last bit of efficiency out of a supercharger.
Not only did he develop teh improved blowers for teh XX adn 40 series
engines, but he came up with the 2-stage blower for the 60 Series and
up, which was what transformed the Merlin from a good engine to a
classic. Two stage blowers weren't new, by any means - the U.S. was
very fond of them in the turbosupercharged R1820s and R1830s used in
the B-17 and B-24, and the V1710 installations on the P-38 and the
prototype P-39. (It was deleted from teh P-39 because there wasn't
room for both the turbosupercharger and the requisite intercoolers,
and installed drag on a tiny airframe like an Airacobra went through
the roof.) and the mechanically driven second stages of the Wildcat's
R1830 and the Hellcat & Corsair's R2800s - but they tended to be
complicated and space-intensive, with teh auxiliarry stage blower
driven at its own optimum speed by a separate drive. Hooker figured
that if he sized things just right, he could have both blowers on the
same shaft, turning at the same speed, and have them match throught th
eperformace range of the engine. And he made it work, with nothing
more than slide rules and graph paper.
Before the 2 stage Merlin appeared, The folks planning Brit War
Production were getting ready to close down Merlin production in favor
of its intended followons - the Sabre and the Vulture. (The Griffon
was another Rolls private venture) It's a good thig that didn't
happen.

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

Peter Stickney wrote in message ...

(Wasn't the Mk VIII actually based on the Mk III, which was
to be a Merlin XX powered flavor that was abandined in favor of the Mk
V when it was decided that the 2-speed Merlins were better off being
put into Hurricanes? It's Rivet Counting, I know.)

The answer is not quite, the Mk III prototype N3297 was used for trials
on the merlin 60 series engines, but it was not a mark VIII prototype.
If anything the mark III was in fact considered a mark IX prototype,
along with R6700 (ex mark I) and AB196, AB197 both ex mark V,
but N3297 was very non standard.

The Air Ministry Certificate of design for the Spitfire Mk III, Merlin
61 conversion, N3297, and for R7600 "Spitfire Special" was
issued on 1 April 1942. This was the mark IX. It appears AB196
and AB197 were the definitive prototypes.

Technically the mark VIII was the mark VII without the pressure cabin,
and some early versions even came with the extended wingtips of
the mark VII. The mark VII prototype was AB450, originally built as
a mark V, there was no official mark VIII prototype.


Rivet count 123 and a third and counting.

Geoffrey Sinclair
Remove the nb for email.

In article , Peter Stickney
writes
In article ,
"Graham Salt" writes:

SNIP
"Peter Stickney" wrote in message
Before the 2 stage Merlin appeared, The folks planning Brit War
Production were getting ready to close down Merlin production in favor
of its intended followons - the Sabre and the Vulture.

You missed out 'YIKES!' here...

(The Griffon
was another Rolls private venture) It's a good thig that didn't
happen.

Mastery of understatement?

Cheers,

Dave
--
Dave Eadsforth

"Peter Stickney" wrote in message
...
In article ,
"Graham Salt" writes:

I had originally thought of the Spitfire as a good example of stretching
when this question first came up. However, on reflection, there was very
little airframe stretch during the service life of this type which
contributed to its ability to maintain parity in air combat. Essentially
there were two major airframe changes (Mk.VIII and F.21), and two major
engine ones (2-stage supercharging in Merlin 60's, and introduction of
the
Griffon). The basic Mk.I led to the Mk.II, Mk.V, and ultimately the
Mk.IX.
The Mk.IX was essentially an interim type allowing use of the series 60
Merlin engine before the definitive Merlin powered Mk.VIII was ready.
With
the introduction of the Griffon engine, the definitive Spitfire was to
be
the F.21 (and followed by F.22, and F.24). Again, to facilitate early
introduction of the engine upgrade, an interim model was introduced,
based
on the Mk.VIII, and called the Mk.XIV.

I have to disagree, a bit. (While the basic Spitfire Shape was
retained, the Griffon engined Spits were much different,
structurally. You couldn't make a Mk IX into a Mk XII with a
conversion kit. The wing structure also evolved quite a bit, as
well. (Wasn't the Mk VIII actually based on the Mk III, which was
to be a Merlin XX powered flavor that was abandined in favor of the Mk
V when it was decided that the 2-speed Merlins were better off being
put into Hurricanes? It's Rivet Counting, I know.)


Not sure what structural difference you are referring to, other than the
provision of a different engine. I disagree with your comments about the
Mk.XII. These were taken off the existing production lines, originally being
built as Mk.V / Mk.IX, and later as Mk.VIII airframes. Apart from
replacement of the tubular engine mounts with a girder mount to support the
new powerplant, there was no other change. The early Mk.XII's had fixed
tailwheels, the later ones retractable, indicating the airframes' original
provenance.This was of course a factory conversion, not a field one, but
nonetheless a simply solution to getting Griffon powered aircraft into the
line quickly. The Mk.XII was the only type to employ the single stage blower
Griffon.

With regard to wing structure evolution, this did not really occur until the
F.21 / 22 / 24 series.

The Mk.VIII was a consolidation of the improvements that were put into the
specialised Mk.VII high altitude fighter, although the pressurised cabin of
the latter was not required or retained.

But the most significant cause of the Spitfire's extended longevity was
the
remarkable work of Ernest Hive's team at Derby in forcing more and more
power from the Merlin engine, and ultimately the successful installation
of
the Griffon engine. Without the engineering brilliance of Rolls Royce,
the
Spitfire, as a contemporary fighter, would have become obsolescent by
1941-42.

T'warnt so mach Hives as Stanley Hooker, and his almost mystical
ability to squeeze that last bit of efficiency out of a supercharger.
Not only did he develop teh improved blowers for teh XX adn 40 series
engines, but he came up with the 2-stage blower for the 60 Series and
up, which was what transformed the Merlin from a good engine to a
classic. Two stage blowers weren't new, by any means - the U.S. was
very fond of them in the turbosupercharged R1820s and R1830s used in
the B-17 and B-24, and the V1710 installations on the P-38 and the
prototype P-39. (It was deleted from teh P-39 because there wasn't
room for both the turbosupercharger and the requisite intercoolers,
and installed drag on a tiny airframe like an Airacobra went through
the roof.) and the mechanically driven second stages of the Wildcat's
R1830 and the Hellcat & Corsair's R2800s - but they tended to be
complicated and space-intensive, with teh auxiliarry stage blower
driven at its own optimum speed by a separate drive. Hooker figured
that if he sized things just right, he could have both blowers on the
same shaft, turning at the same speed, and have them match throught th
eperformace range of the engine. And he made it work, with nothing
more than slide rules and graph paper.
Before the 2 stage Merlin appeared, The folks planning Brit War
Production were getting ready to close down Merlin production in favor
of its intended followons - the Sabre and the Vulture. (The Griffon
was another Rolls private venture) It's a good thig that didn't
happen.

--

I know much credit has been given to Hooker for his work on supercharging
the Merlin, and this needs to be recognised. However, the point that I
wanted to make was that the Rolls Royce team under Hives was something
special, and so was his leadership. It wasn't just Hooker, but Cyril Lovesey
who also worked on supercharging. Hooker was an academic mathematician, and
what he did was remarkable. By his own admission, he was not an engineer
(see his biography "Not Much of an Engineer"), but Lovesey and Rubbra (who
managed the Merlin within Rolls Royce) were, and all formed an incredible
team, without which the Merlin as a power plant for contemporary fighters
was age limited.

Graham Salt

In article ,
"Graham Salt" writes:

"Peter Stickney" wrote in message
...
In article ,
"Graham Salt" writes:

I had originally thought of the Spitfire as a good example of stretching
when this question first came up. However, on reflection, there was very
little airframe stretch during the service life of this type which
contributed to its ability to maintain parity in air combat. Essentially
there were two major airframe changes (Mk.VIII and F.21), and two major
engine ones (2-stage supercharging in Merlin 60's, and introduction of
the
Griffon). The basic Mk.I led to the Mk.II, Mk.V, and ultimately the
Mk.IX.
The Mk.IX was essentially an interim type allowing use of the series 60
Merlin engine before the definitive Merlin powered Mk.VIII was ready.
With
the introduction of the Griffon engine, the definitive Spitfire was to
be
the F.21 (and followed by F.22, and F.24). Again, to facilitate early
introduction of the engine upgrade, an interim model was introduced,
based
on the Mk.VIII, and called the Mk.XIV.

I have to disagree, a bit. (While the basic Spitfire Shape was
retained, the Griffon engined Spits were much different,
structurally. You couldn't make a Mk IX into a Mk XII with a
conversion kit. The wing structure also evolved quite a bit, as
well. (Wasn't the Mk VIII actually based on the Mk III, which was
to be a Merlin XX powered flavor that was abandined in favor of the Mk
V when it was decided that the 2-speed Merlins were better off being
put into Hurricanes? It's Rivet Counting, I know.)


Not sure what structural difference you are referring to, other than the
provision of a different engine. I disagree with your comments about the
Mk.XII. These were taken off the existing production lines, originally being
built as Mk.V / Mk.IX, and later as Mk.VIII airframes. Apart from
replacement of the tubular engine mounts with a girder mount to support the
new powerplant, there was no other change. The early Mk.XII's had fixed
tailwheels, the later ones retractable, indicating the airframes' original
provenance.This was of course a factory conversion, not a field one, but
nonetheless a simply solution to getting Griffon powered aircraft into the
line quickly. The Mk.XII was the only type to employ the single stage blower
Griffon.

Steel Longerons vs. Duralumin, for teh most part. That may sound
trivial, but it wasn't. (Among other things, the longerons had to be
hand-hammered into shape. This wasn't a big deal with the Dural
parts, but bashing the steel into shape was a wholly different matter.


With regard to wing structure evolution, this did not really occur until the
F.21 / 22 / 24 series.

The Mk.VIII was a consolidation of the improvements that were put into the
specialised Mk.VII high altitude fighter, although the pressurised cabin of
the latter was not required or retained.

But the most significant cause of the Spitfire's extended longevity was
the
remarkable work of Ernest Hive's team at Derby in forcing more and more
power from the Merlin engine, and ultimately the successful installation
of
the Griffon engine. Without the engineering brilliance of Rolls Royce,
the
Spitfire, as a contemporary fighter, would have become obsolescent by
1941-42.

T'warnt so mach Hives as Stanley Hooker, and his almost mystical
ability to squeeze that last bit of efficiency out of a supercharger.
Not only did he develop teh improved blowers for teh XX adn 40 series
engines, but he came up with the 2-stage blower for the 60 Series and
up, which was what transformed the Merlin from a good engine to a
classic. Two stage blowers weren't new, by any means - the U.S. was
very fond of them in the turbosupercharged R1820s and R1830s used in
the B-17 and B-24, and the V1710 installations on the P-38 and the
prototype P-39. (It was deleted from teh P-39 because there wasn't
room for both the turbosupercharger and the requisite intercoolers,
and installed drag on a tiny airframe like an Airacobra went through
the roof.) and the mechanically driven second stages of the Wildcat's
R1830 and the Hellcat & Corsair's R2800s - but they tended to be
complicated and space-intensive, with teh auxiliarry stage blower
driven at its own optimum speed by a separate drive. Hooker figured
that if he sized things just right, he could have both blowers on the
same shaft, turning at the same speed, and have them match throught th
eperformace range of the engine. And he made it work, with nothing
more than slide rules and graph paper.
Before the 2 stage Merlin appeared, The folks planning Brit War
Production were getting ready to close down Merlin production in favor
of its intended followons - the Sabre and the Vulture. (The Griffon
was another Rolls private venture) It's a good thig that didn't
happen.

--

I know much credit has been given to Hooker for his work on supercharging
the Merlin, and this needs to be recognised. However, the point that I
wanted to make was that the Rolls Royce team under Hives was something
special, and so was his leadership. It wasn't just Hooker, but Cyril Lovesey
who also worked on supercharging. Hooker was an academic mathematician, and
what he did was remarkable. By his own admission, he was not an engineer
(see his biography "Not Much of an Engineer"), but Lovesey and Rubbra (who
managed the Merlin within Rolls Royce) were, and all formed an incredible
team, without which the Merlin as a power plant for contemporary fighters
was age limited.

No, it certainly wasn't just Hooker. And it wasn't strictly Rolls,
either. Many of the 60 series and later improvements came from
Packard, as well. There's plenty of credit to go around.

Hives deserves a tremendous amount of credit for his vision, and his
willingness to pursue officially unpopular directions. Hives was
willing to back the 2-stage Merlin, and adandon the Vulture. (One
wonders if he subscribed to the "Every ohter Rolls engine is good"
conundrum) and push the Griffon as well. Given the travails of the
Napier Sabre, that was wisdom indeed. (If it were a Curtiss-Wright
Vulture, they'd have stuck to it through the entire war.)
Hives was also the guy who got Rolls into the jet engine business, and
Rover out. This was vital to British jet development. The
Rover-Power Jets feuds had cost more than half a year in engine
development and production.

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

On Wed, 25 Aug 2004 20:17:41 -0400, (Peter
Stickney) wrote:

Before the 2 stage Merlin appeared, The folks planning Brit War
Production were getting ready to close down Merlin production in favor
of its intended followons - the Sabre and the Vulture. (The Griffon
was another Rolls private venture) It's a good thig that didn't
happen.

Whatever do you mean? Surely the war would have ended a lot sooner
with fleets of Sabre-engined Lancasters darkening the skies and the
emergency runways at Manston and Woodbridge after multiple engine
failures?

Gavin Bailey

--

But, first, want speed. Bart not greedy as all know. 250MHz enough.
I attempt use SGI chip in MB. But chip not fit, then I bend pins. Shove in MB hard.
Now apply hammer. Yeah, sit down, ****er! Power on, go BEEEEEP! - Bart Kwan En

Presidente Alcazar wrote in message . ..
On Wed, 25 Aug 2004 20:17:41 -0400, (Peter
Stickney) wrote:

Before the 2 stage Merlin appeared, The folks planning Brit War
Production were getting ready to close down Merlin production in favor
of its intended followons - the Sabre and the Vulture. (The Griffon
was another Rolls private venture) It's a good thig that didn't
happen.

Whatever do you mean? Surely the war would have ended a lot sooner
with fleets of Sabre-engined Lancasters darkening the skies and the
emergency runways at Manston and Woodbridge after multiple engine
failures?

Gavin Bailey


There was no problems in the sleeve valved Napier Sabre that hadn't
already been solved by Bristol in its succesfull sleave valve
radials. In fact the Napiers problems were solved with Bristols
help.

The Vulture was simply 'developed to death' to provide increasing
power for the over specification weight Manchester.

The same fate befell the Junkers Jumo 222 which underwent 2 bore and 1
stroke change to increase power to keep up with airframe size weight
increases. As a result the engine was pushed to a new limit just as
the last set of teething problems had barely adaquetly been solved.

In article ,
Presidente Alcazar writes:
On Wed, 25 Aug 2004 20:17:41 -0400, (Peter
Stickney) wrote:

Before the 2 stage Merlin appeared, The folks planning Brit War
Production were getting ready to close down Merlin production in favor
of its intended followons - the Sabre and the Vulture. (The Griffon
was another Rolls private venture) It's a good thig that didn't
happen.

Whatever do you mean? Surely the war would have ended a lot sooner
with fleets of Sabre-engined Lancasters darkening the skies and the
emergency runways at Manston and Woodbridge after multiple engine
failures?

Just so - there's no doubt at all that the war would have ended
earlier. But then, we'd probably all have umlauts on our keyboards.
I find it amazing, in some ways, that Sabre development was so
persistant. After the blinding success of the Napier Dagger (Same
configuration only smaller) engined Hereford (Hampden with Rapiers)
Medium Bomber Motorglider.


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