Vickers VC.1 Viking

[steelpillow]

The Vickers VC.1 Viking began life as the Wellington Transport Aircraft, under Air Ministry Specification 17/44 (according to Wikipedia). The idea was to keep the wing and undercarriage of the good old "Wimpy" but to develop a new fuselage.

I just found this on t'interweb thingy: "the postwar Vickers Viking airliner was designed with geodetic structure (covered in glass fibre reinforced fabric) then redesigned conventionally to be more saleable" Is there any truth in this? If so, would the change have been made before or after 17/44 was issued?

 

[Jemiba]

You know this thread, don't you ?
http://www.secretprojects.co.uk/forum/index.php/topic,13925.0.html

 

[steelpillow]

Ah, thank you. I was thinking postwar so i didn't look at anything titled "early".

Nothing about the change from geodetic to conventional structure, though.

 

[dogsbody]

A drawing:







Chris

 

[Stargazer]

Splendid plan, Chris, thanks.

 

[Apophenia]

Indeed. Granger did great stuff!

On that " geodetic to conventional structure" bit, the first 19 Vikings had fabric-covered Wellington wings. But was the wing structure completely redesigned for BOAC? Or was that geodetic structure simply 'planked over' with dural sheeting?

 

[robunos]

Both! ;D B)

"From the outset,Vickers' design team had a fully stressed skin aeroplane in mind, but at first they proceeded only with a stressed skin fuselage and a fabric covered geodetic wing...There was good reason to proceed with the stress skinning, because the potential operator, ...British European Airways, was not keen to accept fabric covering, since it would have increased the problems and complexity of their maintenance engineering. As it happened, the change from fabric covered Vikings to the stressed skin versions took place after 19 of the former had been produced.
The inner plane of the geodetic wing was retained. Between the wing roots and the engine mountings and cowlings, the exposed surface of the inner plane was skin plated instead of fabric covered. The outer sections were based on a continuation of the Wellington single main spars system, with auxiliary spars for attachment of the leading edge, split flaps, and ailerons.
The Warren braced tubular booms of the centre section and inner plane main spar were pinned to the new machined and fabricated I-section outer main spars through massive links located at the outboard sides of the engine mountings. The stressed skin of the outer planes was riveted to chordwise stringers, with the load bearing stiff ribs spaced widely across the span."

Source :- Putnam's 'Vickers', pp.399-400.

cheers,
Robin.

 

[taildragger]

A question for aerostructures experts:
Is there any reason why a stressed skin structure couldn't use geodetic construction? It would seem to me that the same efficiency provided to fabric-covered structures would apply, to a lesser degree, to semi-monocoque airfames.

 

[Schneiderman]

Well you could, but wouldn't that be a sort of belt-and-braces approach? I always think of a geodetic framework as a form of stressed skin with holes in, but someone with real structural knowledge may tell me I'm talking b******

 

[Hobbes]

Stressed skin with geodetic construction gets you something like the milled panels used today, where webbing is only used in the places where it's needed. Makes for a far lower parts count than geodetic construction, at the expense of repairability.

 

[Nick Sumner]

Wasn't the Warwick geodetic construction and stressed skin?

 

[kitnut617]

Wasn't the Warwick geodetic construction and stressed skin?

No, if the wiki article is correct

 

[Schneiderman]

Wasn't the Warwick geodetic construction and stressed skin?

No, and neither was the Windsor that followed.

 

[steelpillow]

Is there any reason why a stressed skin structure couldn't use geodetic construction? It would seem to me that the same efficiency provided to fabric-covered structures would apply, to a lesser degree, to semi-monocoque airfames.

The main point of geodetic construction is its load-spreading which gives better efficiency and damage tolerance compared to the rectangular-based frames and longerons. But then, that is also the main point of stressed-skin construction. In a semi-monocoque, the frame members are there primarily to stiffen the stressed skin (and sometimes help carry a directional load) and geodetics have no special advantage there.

 

[Hood]

As ingenious as it was for the time, Vickers really did stick with it for too long. I guess the demands of wartime tooling and workforce training were incentives to keep using it on the Windsor, and the Viking was a temporary civil offering anyway and using off the shelf wings probably saved quite a bit of design time and cost.
Even the Warwick though suffered from ballooning of the wing fabric under certain conditions and high speeds.

 

[riggerrob]

The experimental, 4-engined Windsor bomber had a complex geodesic airframe. Geodesic because that was the construction method already used in Vickers’ factories. Higher speeds rendered (doped) Irish linen too weak and too flexible. Windsor was skinned with a special fabric woven with steel wires and steel ribbons.
With all those thousands of load-paths, Windsor would have shrugged off the vast majority of battle-damage, but was a production engineer's nightmare!