This Supersonic Age

[GPMG]

So Jetex Jim, your saying that the Merlin was a poorly designed engine? Or that Packards understanding of correct tolerances was different to Rolls Royce's?

[8-15fromOdium]

Back to the origins of this thread...

Found some cracking films in the National Archive thread, my personal favourite being:

http://www.nationalarchives.gov.uk/f...lmpage_wtw.htm

make sure any speakers you have are turned on full. The film tells us what the CAS & the AFB do (pertinent to another popular thread at the moment). It also has some American stuff in it to keep JJ happy (not the B-57).

Apologies if this has been posted before, I'm fairly new.

[Jetex Jim]

So Jetex Jim, your saying that the Merlin was a poorly designed engine? Or that Packards understanding of correct tolerances was different to Rolls Royce's?

As I understand it the engineering drawings did not define the tolerances as well as those typical in a 1940 US car plant, RR adopted the position that all aero engines must be assembled by skilled fitters, which is quite costly but permits a lower investment in fixtures and good quality drawings.

Similarly D Haviland assembled the Comets with the minimum of tooling, as we know from BAE most recent excuses all those old airframes are different, as is often reported regarding Vulcans, etc.

This sadly seems typical of British engineering, and actually it doesn't matter that much if you only build small handfulls of aircraft.

Which is why I call it a cottage engineering approach.

Thats not to say that the Merlin was a bad design, just that RR were like so many British companies trying to balance their budgets week by week instead of investing.

By the time Packard had finished re-drawing the original blueprints they could assemble engines as good for far fewer manhours.

[goudie]

Which is why I call it a cottage engineering approach.

I think Jetex has a point. Whittle's attempts to develop the jet engine is a typical example.
Designing and building large aircraft requires massive amounts of highly skilled labour that can be hired and fired at will (Boeing policy).
With all the will in the world the UK or for that matter other European countries could never produce the manpower and funding required to go it alone, hence the joint venture that has produced Airbus

[Jetex Jim]

Boeings' observations regarding the Comet were that DH seemed to be hammering them together in a shed in Hatfield using less tooling than they would typically use on a one off prototype.

One might also observe that in terms of 'cost of ownership' British aircraft were somewhat lacking, much as I love the Lightning having seen the engines fitters burning the midnight oil taking out the top engine yet again because a nut or washer, on an engine change has dropped down and the whole engine has to be pulled because the lose articles can't drop through.

And lets not even get on to the ergonomics of the cockpit or the lack of nose wheel steering .

Ships spoiled for a haporth of tar comes rather easily to mind.

In fairness to the aircraft industry its perhaps worth remembering that aviation is not the only area where Britain made innovative strides and failed to capitalise on them through under investment.

Britain’s have for years been happy to foster the notion that we are so smart that we can maintain technical leadership in a demanding fields without sensible levels of capitalisation. One can see how such a line would work at corporate level

And the industry itself has pushed the myth that if it wasn’t for those neddies in Whitehall the British Aircraft industry would have capitalised on it post war lead and still be a major force. For me without the forced megers of the 60’s and 70’s there’d be no industry left to carry on whining about Whitehall bullying, American bullying or even the poor quality of its own legacy products. Indeed the fattest balance sheet years for BAE were the ones when it was capitalising on the sale of all those older establishments, turning those old aircraft factors into shopping centres and multiplexes.

In fact one might argue that one of Duncan Sandy’s big mistakes was not forcing industry to concentrate on missiles in the 1960s, after all he, unlike most of the aviation pundits and writers of the time had been privy to German wartime research in guided missiles, and this was information that didn’t come generally to the public eye until the mid seventies. Though one suspects that a pilot centric air force that was aware of what had been wasn’t keen to go down that route.

But for all that I still love the Lightning.

[GOLF_BRAVO_ZULU]

Originally Posted by Jetex Jim

Similarly D Haviland assembled the Comets with the minimum of tooling, as we know from BAE most recent excuses all those old airframes are different, as is often reported regarding Vulcans, etc.

How "often" has that been reported? AVRO built their later machines in a totally different way to De Havilland, Handley Page and Vickers. High mass, temperature compensated jigs, including the use of Fairey patent envelope jigs, provided a build accuracy rarely achieved for Comets at Hatfield and Nimrods at Hawarden.

Sorry but it's not wise to tar all British manufacturers with the same broad brush. As the CF105 was mentioned earlier, it is notable that much of the production expertise at Chadderton and Woodford was utilised in Malton.

[Cyclone733]

Although older manufacturing processes may not have been as precise as newer methods, I was trying to get at the fact that bolting a precision wing to an airframe that has been in a salt water environment at low level at reasonably high speeds and loads may not be exactly the same shape as it was when it left the factory almost 40 years ago. Still can't see how a new cabin would add that much to the project cost

[Jetex Jim]

How "often" has that been reported?

My comments regarding Vulcan differences should have been more carefully worded. However the acount of the Vulcan Black Buck raids (my copy out on loan so I can't check wording) does record that when it comes to Vulcans some were more equal than others. Other postings on this forum that suggest there were often considerable handling and performance differences between aircraft of same type and model. Recent comments regarding Lightning performance for example. But perhaps they all left the factory with identical characteristics and then drifted over time due to local rigging practices etc.


Regarding the planemakers generally one might argue that even in wartime the country has not been best served by its industry and procurement policies. The Lancasters, Halifaxes and Sterlings were all equiped with power operated turretts and while these made good sense for the American daylight raids where aircarft flew in tight mutually defensive box formations and moreover had effectivly gunned turrets that covered the aspects where fighters flew, which is to say underneath. This equipment made far less sense for night time raids.

The gunners, it is said, rarely saw the aircraft that shot them down and the turrets made for a heavy performance penalty. The astronomer Freeman Dyson, many years ago produced an acount of his wartime years in Operational Reasearch. OR had produced reports that 4 engined heavies without turretts would fly significantly higher and faster. Indeed the German radar equiped nightfighters of the time were very performance limited. Moreover in the event of the total loss of an unturreted aircarft the loss of life would have been less.

And of course those unharmed Mosquitos managed quite well and when the V bombers were being speced they were ungunned.

However its probably debatable if this is a specification or a design issue though I assume that messers Dowty etc didn't argue too hard against fitting turrets.

[GeeRam]

Originally Posted by Jetex Jim

As I understand it the engineering drawings did not define the tolerances as well as those typical in a 1940 US car plant, RR adopted the position that all aero engines must be assembled by skilled fitters, which is quite costly but permits a lower investment in fixtures and good quality drawings.

There was nothing particularily wrong with what RR had done. RR designed the Merlin in peacetime to it's traditional methods of low volume and high quality.
The war resulted in the urgent requirement to mass produce a product that had not been designed for mass production, which is why HMG went to the USA, and as you say Packard had to reverse engineer the engine (under the leadership of Jesse Vincent) to produce the required engineering drawings to enable the engine to be built on a mass assembly line in the way they were used to doing it and that suited their tooling.

However, it's often quoted that the RR versions were nearly always more powerfull than the equivilent Packard version, but that the Packard versions were generally more fuel efficient.

[GOLF_BRAVO_ZULU]

Wasn't that because the Packard jobs had Stromberg carbs whereas the home growns had SUs?

[GeeRam]

Originally Posted by GOLF_BRAVO_ZULU

Wasn't that because the Packard jobs had Stromberg carbs whereas the home growns had SUs?

Merlin Types 66, 70, 76, 77 & 85 used the Bendix-Stromberg carb, all others used SU I believe.

[India Four Two]

Packard had to reverse engineer the engine (under the leadership of Jesse Vincent) to produce the required engineering drawings to enable the engine to be built on a mass assembly line

This episode is well documented in Stanley Hooker's autobiography "Not Much of an Engineer". He designed the two-stage superchargers for the Merlin and went on to become Rolls Royce's Chief Engineer.

The book is a great read by the way.