Class 91/Mk4/225 preservation?

91119 was looking good last night. Really good.
Well done everybody.

 

Just out of interest, a 9 month overhaul. How does that measure by usual standards? And just a thought, if it had been a volunteer group how long do we think a similar overhaul would have taken? 20 years? 10 years?

 

Not so much an overhaul, as a major rebuild following severe damage in the winter. I've seen rumours elsewhere that a recent failure of 91120 has been terminal.

 

Having grown up near Peterborough and being in my early teens in the late eighties, I remember being blown away by how beautiful and cutting edge the 91s looked. I was excited to have loco hauled stock back on the ECML (although I'm now rather more fond of HSTs than I was back then - hey, I'm even looking forward to seeing 442s back on SWR!) and have a number of (poor) photos of 91s on test with rakes of Mk1s. Also, having the unusual attribute of having an aerodynamic end and a flat end made them more intriguing!

 

They made their first appearance just before my father died: he thought they looked magnificent.

 

One thing to remember is that when built, the class 91s were fitted with all sorts of fancy 'state of the art' electronics. Unfortunately given the raid advances seen in electronic / electrical / computer based technology over the past 25 years much of that 'state of the art' kit is now well and truly obsolete / unavailable to purchase.

As such if the damage was to things like control cards, electrical cubicles, etc repairing them or organising someone to make them is not a straightforward task for todays TOCs.

Thats the one advantage steam and early diesels have - while new items may have to be made, machining / welding / wiring up basic relays is unlikely to be impossible to do. Getting hold of ancient semiconductors ob the other hand.

 

Not as difficult as you might think. There are a number of companies that specialise in this field, and sometimes newer/better devices can be pressed into service with some slight modifications.

 

I wonder if they are easier/harder to procure than a new Deltic engine or boiler/frames for an A4 (to compare with their predecessors).

 

I think a good example is what the ACLG are doing with 89 001 - a loco from the same generation.

Certain types of e.g. TTL are difficult to source new, but NOS isn't overly difficult. (Been there, done that). I mean, radio and TV valves aren't difficult at all except for a few types.

 

When 90's appeared on the WCML, Liverpool drivers dubbed them 'Skoda's.' When they worked over to Leeds and York on Trans-Pennine jobs and saw the 91's, they named them 'Skoda hatchbacks!'

 

Those would be a good deal harder, I'd imagine. I know that it became impossible to obtain new parts to keep the Vulcan flying.

 

Actually the issue was not parts - more that BAE systems and Rolls Royce felt unable to continue to bankroll / maintain the skills necessary to inspect and certify the ones installed on the aircraft needed to prove they were safe and fit for service.

From a purely technical perspective there was no reason why the Vulcan had to retire when it did - nothing broke and even after it touched down for the final time, it could have easily taken off again the very next day. The reason it has remained on the ground ever since is precisely because it would be illegal to fly it without the technical support from the manufacturer.

This stance has been reinforced following the Shoreham Airshow disaster where the CAA have been VERY wary about amateur organisations / individuals operating jet aircraft, particularly complex ex military ones. Basically either the aircraft must be currently supported from a technical perspective by a manufacturer (e.g. Bombardier, Airbus, etc) or it must be under the direct ownership and operation by the UK military (who are not going to operate kit without technical support from the manufacturers anyway).

 

Get it to Didcot. They’ll shoehorn a different motor in and rebuild the frame with ex-Barry bits of Hall and 8f… back in the air in no time.



Simon

 

Correct. Aircraft from around the 50's onwards are subject to incredibly strict rules around the service life of components. The only reason the Vulcan was possible was because it was withdrawn from the RAF heritage flight straight into a private ownership who continued to maintain it and run it according to schedule, and the discovery of 8 freshly overhauled, sealed and inhibited Olympus engines. Even so, those engines immediately meant it could only ever have so much time airbourne-I think they were good for up to 8 years service? So 2 sets= no more than 16 years. In the event, two engines blew up, so it was less than that. Rolls-Royce do not have the tooling, or anything else to overhaul and make new bits for Olympus engines, so in the absence of tens of millions of pounds suddenly appearing, they were always going to be the last ones ever to fly.
The biggest bit of the project was finding the manufacturer of every single part, tracking down their modern day successor and getting approval. Also, the airframe had to have a fix to the wing root, which was identified and drawn up at the end of their service, but never done. Another such fix was known to be needed about the time of its retirement, which was a contributing factor to its final withdrawal. It can still do fast taxi runs.

Older aircraft (Lancasters, spitfires etc) weren't designed with life limits on parts, and so can generally be rebuilt indefinitely. As the manufacturers are untraceable, they fly on a grandfather rights system, basically they must be maintained as per the last servicing specs. Again, most of the work is tracing papers.

 

Be the 8th wonder of the world if somebody could build a new deltic engine from scratch!!!!

 

I think one or two model engineers have succeeded. People said the same things about making new bits of mobile kettle, and yet we see the likes of Galatea, Royal Scot etc happily chuffing about.

 

Utmost respect for the model engineers, but getting one to produce 1650bhp, getting cylinders chromed, 2 part pistons manufactured etc.. would be a great feat...

 

Actually, there's no reason why it couldn't be done. After all, it's 1950's machinery we're talking about. The stumbling block would be the cost, I suggest.

 

That was my point. None of it is any kind of lost, arcane knowledge-although I understand that the knowledge of how to build them up just right is being lost. Some processes/materials will be obsolete, but due to being replaced by better versions.
As it happens, the remaining deltic engines are on their last legs-all ran way beyond their official maintenance schedules, and these were engines designed with "lifed" components. As is well known, they were designed to have the engines swapped out routinely, as per aero engines. Someones's going to have to start running off batches of rods, pistons and liners fairly soon, or they'll all be unusable. Thankfully, everything else of the era was built to last.

 

See the model in the NRM by Roy Amsbury for one such example.