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By Genghis the Engineer
FLYER Club Member  FLYER Club Member
#1133799
Rob P wrote:Ah... Mrs Grace's favourite. :shock:

Fails to provider any answer to the OP question though.

petestorey wrote: ... why can't you simply (ahem) take the original blueprints, and build a new one from them?


Rob P


Here's an example, in my day job I've been worrying this last month about a fuel system problem with one-off BAe-146 variant. Nothing apparently insoluble, some deficiencies in the fuel hose and connections, causing some leaks, that weren't then venting to the outside of the aeroplane properly. Easy you'd have thought - it's been okay for the last umpty-ump years, just replace the hoses and fasteners and all will be fine.

Except that the hoses came off a late model BAC 1-11, and are no longer manufactured. Worse, they're in a material which nobody anywhere in the world manufactures any more, and of a diameter that nobody manufactures any more either.

Change those, and we've changed the design, and have to start re-making, redesigning, and recertifying the fuel tank attachments as well of-course. And suddenly an apparently simple fuel leak will cost several tens of thousnads to fix.



Now extend that to a Spitfire. You may well have a set of blueprints, and if you're lucky designs for the several thousand modifications and production modifications which were also made to it. But almost certainly the airframe will have been made of aluminium alloys that no longer are made, because they've been "improved", the fuel hoses will be of gauges and materials no longer available, the instruments are no longer manufactured, the sutton harness was a dodgy item at the best of times, so you'll want to change that for something more modern, the original WW2 parachutes will no longer exist, so you'll need to use something more modern, which will mean modifying the seats. Almost certainly some of the lubricants will be based upon whale-oil, so you'll need to specify something different, and raise a design variation to approve that....

... so basically building an identical replica from plans of a vintage aeroplane (or even the extended range fuel system for my BAe-146 which is only 30ish years old) is impossible. Any replica is substantially a design exercise, you can't avoid it.

G
User avatar
By Rob P
#1133831
So the only practical route is a rebuild

There are enough Spitfires around now to support a fairly healthy cottage industry making all of the components and systems that are needed.

But for a 'rebuild' you need a dataplate off the original aircraft. Everything else can be factory new

Hence the potential value of the Burma dig, even if only powdered bauxite remains of the airframe, as long as the dataplates survive.

Rob P
#1133980
“So the only practical route is a rebuild”

No, not in the examples I gave above. In the case of the LAA, you can replace any hose with a modern equivalent which is at least equivalent for the job in hand. This would not apply to a 146, but would apply to the Cygnet I quoted above. Another example would be a machine with an unreliable and unobtainable engine. No issue with using a suitable alternative.

Rod1
User avatar
By Genghis the Engineer
FLYER Club Member  FLYER Club Member
#1133991
Rod1 wrote:“So the only practical route is a rebuild”

No, not in the examples I gave above. In the case of the LAA, you can replace any hose with a modern equivalent which is at least equivalent for the job in hand. This would not apply to a 146, but would apply to the Cygnet I quoted above. Another example would be a machine with an unreliable and unobtainable engine. No issue with using a suitable alternative.

Rod1


"no issue" - I disagree.

All these substitutions can be made - engines, materials, propellers, tyres, instruments, you name it. Absolutely.

But, whilst they can all be done under any airworthiness regime, whether the part 25 of my 146, or the LAA regime of your MCR01: all those decisions still need making by somebody, in most cases confirming by somebody else, and documenting. It's just that the bigger and heavier the aeroplane, the more complex the decision making and documentation process gets.

G
User avatar
By Rob P
#1134060
Wouldn't one struggle to get a VS Spitfire on an LAA Permit Rod?

Rob P
#1134196
Rob, the OP used a spit as an example, I used a 262...

EtE I was trying to redress the balance. My first Permit aircraft was a 1947 C120 and I do not remember fitting many original manufacture bits to it. I am friends with the guy who re-engineered the Cygnet in my example above. He did not have any issues with fuel hose, used modern equivalents and showed "good engineering practice" - the aircraft is flying. I know of several others who have managed it with only reasonable levels of compliance with "good engineering practice". Rob had gone away with the idea that building a replica was impossible, that is defiantly NOT the case.

Good luck with the 146 – nice to chat to someone else with an interest in it that is other than flying one. :wink:

Rod1
User avatar
By nallen
FLYER Club Member  FLYER Club Member
#1134215
basically building an identical replica from plans of a vintage aeroplane ... is impossible


Though perhaps less so if it's wooden -- there is a new Comper Swift under construction that should fly this year:

http://www.flickr.com/photos/tupperware_pilot/7620036862/in/set-72157630690242988
User avatar
By Genghis the Engineer
FLYER Club Member  FLYER Club Member
#1134248
Actually pretty much all wooden aeroplanes require a lot of engineering assessment on alternate woods, testing of samples, confirming bonds - they same very much applies.

But as I said, it's not an issue, it just needs doing.

G
User avatar
By Genghis the Engineer
FLYER Club Member  FLYER Club Member
#1148882
golfcharlie wrote:The other way to go is to take an LAA-accepted aircraft design (e.g. the Flitzer) and modify to convert to the profile of your desired type.
If I had the time etc., mine would be a Gloster Gladiator....
Less hassle? Maybe.


Vastly easier in my opinion, but still far from simple.

G
User avatar
By Pitts Pilot
#1157907
Rod1 wrote:petestorey

There are replica aircraft which appear to be what you are asking. An example would be the Hawker Cygnet which has been reproduced in modern times. On the military front then it depends how deep your pockets are. In January 2003, the American Me 262 Project, based in Everett, Washington, completed flight testing to allow the delivery of near-exact reproductions of several versions of the Me 262 WWll Jet!

Rod1


I think it is much easier in the USA
They seem to be able to do what they like and call it Experimental
Dave
User avatar
By Genghis the Engineer
FLYER Club Member  FLYER Club Member
#1166784
Pitts Pilot wrote:
Rod1 wrote:petestorey

There are replica aircraft which appear to be what you are asking. An example would be the Hawker Cygnet which has been reproduced in modern times. On the military front then it depends how deep your pockets are. In January 2003, the American Me 262 Project, based in Everett, Washington, completed flight testing to allow the delivery of near-exact reproductions of several versions of the Me 262 WWll Jet!

Rod1


I think it is much easier in the USA
They seem to be able to do what they like and call it Experimental
Dave


So the paperwork is a bit simpler.

The engineering decisions are exactly the same.

G