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Stretching WW2 Designs



 
 
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  #11  
Old August 26th 04, 07:12 AM
Geoffrey Sinclair
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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.


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  #12  
Old August 26th 04, 10:06 AM
Dave Eadsforth
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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
  #13  
Old August 26th 04, 01:51 PM
frank may
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I'm not sure the B-54 would count since it never was built. OTOH, the
Tu-4 was stretched even further than a B-29; the Tu-80 & even bigger
Tu-85, & to an extent, even the Tu-95. Tupolev had a number of other
stretches proposed, but not built. The B-36 was stretched to the XC-99
& even the YB-60. I suppose the F-82 could be considered a stretch of
the P-51. The Heinkel He-177 was developed into the He-274 or
something. I think that was a stretch anyway. Sorry for any
duplications from previous posts if I made any.


"Kyle Boatright" wrote in message ...
One aircraft which was stretched considerably was the B-29. It eventually
morphed into the B-50, the B-54, the C-97, the KC-97, the TU-4, the Guppy,
the Super Guppy, and probably a few more variants I've left off.

  #14  
Old August 26th 04, 07:50 PM
Graham Salt
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"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


  #15  
Old August 26th 04, 09:00 PM
Peter Stickney
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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
  #16  
Old August 27th 04, 05:52 AM
WaltBJ
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You must take into account that any such 'stretching' will affect
production, so unless a marked increase in performance is attained the
stretch isn't going to happen. Wartime priorities all involve time,
and losing production for a minor advantage isn't going to happen. The
stretch to the 190D was because of the drastic engine change,
involving more length and weight up front countered by a longer aft
fuselage. The long wing on the TA152 was for high altitude work; the
original BMW-190 couldn;t get up there and the 109G/K could but wasn't
good enough by 44. BTW The B50 started out as the B54. Why the change
I don't know, unless it was appropriation bills, playing games with
which which changed some other designations (whence the F86D, formerly
the XF95, ISTR).
Walt BJ
  #17  
Old August 27th 04, 11:29 PM
frank may
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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.

  #18  
Old August 31st 04, 09:30 AM
Presidente Alcazar
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On Tue, 24 Aug 2004 08:47:13 -0400, (Peter
Stickney) wrote:

The P-40Fs and P-40Ls were also outperformed by various
Allison-powered P-40 models as well.


Mmm, depends on height and chronology, though. Certainly in mid-1942
the Merlin engined variants were preferred for both the USAAF and RAF
on performance grounds over the contemporary Allison models. I think
that's easy to overstate, though. Production availability was the
main determinant. By 1943 there were only Allison variants being
produced, which is when (in the second half of the year) Packard
started to deliver Merlin 60-series engines. The Spitfire, Mosquito
and Mustang were all airframes with a better claim for the increased
performance of the Merlin 60 series than the P-40. Meanwhile, the
1943-vintage P-40s with Allison engines were clearly better performers
at lower altitudes, which is where most of their operational
employment took place, so there was no sense in using Merlin 20-series
production for them in 1943.

The single stage Merlins, while
very, very good engines, weren't the leap in performance over its
rivals that the 2-stage (60 series and up) engines were.


Sure, but I know the RAF specifically preferred the Merlin-engined
variants, and the allocations of USAAF-controlled P-40s indicates that
when Merlin-engined variants were coming off the production lines, the
USAAF wanted them in preference to Allison-engined variants being
produced at the same time, which they directed to lend-lease supply
for Britain, Australia, New Zealand and Russia. I appreciate the
performance differential involved was marginal, but it does seem to
have influenced procurement policy.

Having said that, those decisions were the ones made in early to
mid-1942, and by forces which relied on P-39s and Hurricanes for the
mainstay of their operational fighter strength. When exposed to the
FW 190, by early 1943, senior commanders in North Africa were
demanding better performance fighters than the P-40L and the Spitfire
V which themselves had been the favoured options less than a year
earlier.

A couple of points here - the Griffon's frontal area wasn't that much
more than the Spitfires, and it was notably wider only at the top of
the cylinder blocks and heads. It wasn't that much longer overall,
either, due to clever relocation of the engine accessories.
While the Griffon Spits may have lost some of the Spitfire's perfect
handling, it didn't lose much. and the Royal Navy was flying them
from carrier decks into the 1950s. I couldn't have been that bad.
(They chose to dump the Corsair and keep the Seafires, after all.)


Well, some of that comes down to the exigencies of supply politics,
e.g. the end of lend-lease and the termination of any substantive
dollar-procurement programmes due to lack of dollars. I think the
Seafire was an underestimated carrier fighter, but if I'd had the
option in late 1945 I would have kept the FAA on (certainly) Hellcats
and (possibly) Corsairs.

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
 




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