plans for 7.25 gauge rocket

[wendy jacksonParticipant @wendyjackson]

hi, can anyone point me in the right direction for a set of plans for a 7.25 rocket loco, or something like this loco. thanks, michael

[wendy jacksonParticipant @wendyjackson]

[WearyParticipant @weary]

Don't know if you have seen this thread, which might give you some leads.

Regards,

Phil

[SpringbokParticipant @springbok]

Seen a lot of the bits going on ebay might still be up for sale

Bob
Had a look

Item No

190808020588

but not long to go

Edited By Springbok on 16/03/2013 10:11:42

[SpringbokParticipant @springbok]

Terry could I mention this for 2 locos

Bob

[jason moore 1Participant @jasonmoore1]

The book mentioned in the other thread really is worth it's weight in gold in my opinion. Anyone who has an interest in Rocket really should not be without it. There is easily enough information in the book to build a very accurate model of Rocket,the sticking point in this country still being the boiler.

I did contact the gent in Australia who very kindly replied but of course as the rules for the construction of boilers are different over there this remains a problem.

I am not aware of a published design for Rocket,which i find surprising but i suppose people are dismissive of the passenger hauling ability even in 7 1/4" gauge.

I am still planning to build Rocket sometme in the future even if it can only be run in my own garden.

[wendy jacksonParticipant @wendyjackson]

Thanks chaps, I have seen a 7.25 reainhill loco, that looks something like the rocket, are there any details about the 7.25, all i have come across is for a 3.5 engine. michael

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

There are two mentions of twice size Rainhill's in 1960's (ish) ME's :

One that ran on Ken Swan's ' Derwent Valley ' 7-1/4 inch gauge railway .

One built in a school workshop by a metalwork teacher and his class .

No actual construction series but plenty of information and pictures .

The one on Ken Swan's line is shown in a pictures hauling a good load of passengers . This seemed a very attractive engine whereas the school one was a bit of a lump but apparently still ran ok ..

Michael Williams .

 

Edited By MICHAEL WILLIAMS on 16/03/2013 13:10:01

[Sub MandrelParticipant @submandrel]

I did contact the gent in Australia who very kindly replied but of course as the rules for the construction of boilers are different over there this remains a problem.

I don't know if the book covers this, but the cylindriical part of Rocket's boiler is a separate construction from the firebox, the two being joined by circulation tubes. Stephenson must have been wary of the chances of getting the water tubes tight if one end had to be worked from inside the firebox.

If I recall the Japanese mass-produced version (OC?) had the boiler made in two parts as per the original, and I assume was accpetable to British boiler inspectors.

Rocket ought to be a reasonable hauler in 7 1/4"  – not huge trains, but the boiler in 3 1/2" gauge would be about the same size as Tich, so eight time the volume, it should be able to pull several folks, even allowing for the larger wheel diameter and single wheel arrangement.

Neil

Edited By Stub Mandrel on 16/03/2013 13:15:42

[jason moore 1Participant @jasonmoore1]

The problem as far as i am concerned with the boiler for a scale Rocket is the old published design argument. I know some of you out there have very understanding and competant boiler inspectors willing to sign off new designs as long as the sums have been done correctly,unfortunately in my club no published design means no boiler,simple as that.

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Can someone explain to me why boilers built to published designs should be considered in any different way to boilers built to an individuals personal design ????

Michael Williams

[Phil H 1Participant @philh1]

Jason,

I would be very interested to hear the answer to Michael's question.

Simply having a very suspect published design (suspect because there seems to be many errors on the published model drawing sets with no revision control) is no use to any competent inspector.

How on earth is your inspector passing the boilers i.e., based on what????

PhilH

[Sub MandrelParticipant @submandrel]

I imagine that the design being 'published' is being used by the testers to absolve themselves for having to check it, on the grounds that "if it was dodgy someone would have spotted it, wouldn't they?"

Neil

(edit – being a bit harsh…)

Edited By Stub Mandrel on 17/03/2013 11:19:04

[jason moore 1Participant @jasonmoore1]

Errors in drawings is one thing,perhaps a measurment off or a decimal point in the wrong place but i do not believe there are many, if any boiler designs published that are dangerous. I know that in the old days of the Model Engineer all designs where checked by qualified persons,i am not sure about the situation now.

The boiler inspector in my club will only consider inspecting a boiler if it is to a published design.That way the design has more than likely been built before and found to be a good design, so as long as the workmanship is up to standard then the boiler will be a safe one.

I suspect that he does not feel qualified enough to sign off a new design or is being extra cautious in today's modern society or a little of both.

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi Jason ,

Very few published designs have ever been checked properly by anybody – not by the original designer or anyone since .

It is only in very recent times that published designs for boilers have had any thought put into them .

The late Neville Evans is the only boiler designer that I know of that went through the whole process of designing the boiler in detail ,  getting calculations done , revising design and calculations as nescessary and then having final design double checked by a professional boiler maker .

He didn't bother with any club boiler inspectors and neither would I . 

Michael Williams .

Edited By MICHAEL WILLIAMS on 17/03/2013 14:09:47

[wendy jacksonParticipant @wendyjackson]

chaps.,my post was about plans for a rocket, not about boilers.

[V8EngParticipant @v8eng]

Hi Terry.

Have you seen this?
http://www.model-engineer.co.uk/classifieds/view_ad.asp?ad=7328

Edited By V8Eng on 17/03/2013 15:53:40

[jason moore 1Participant @jasonmoore1]

Regarding the original post about Rocket i take the point and this thread could spiral into a debate about boilers which has been done before many times.

As far as the design of boilers goes i wont argue with Michael about how good or bad past designs have been, but if i or anyone else wishes to run a steam locomotive on a club track then a boiler inspector has the last word and is responsible for the issue of hydraulic and steam test certificates.

[nigel jones 5Participant @nigeljones5]

I dont understand the fuss about designing boilers or getting them inspected, Rocket or otherwise. There is plenty of info and equations on the net to more than prove to an inspector that it is safe – they just dont want to hear it!

[SpringbokParticipant @springbok]

Lets get back to the thread and help Jerry,, Boilers have been done to many times.

Bob

[Brian Baker 2Participant @brianbaker2]

Greetings, it would appear that the boiler Inspector mentioned by Jason moore 1 is acting quite correctly, and observing green book rule 3.9 (c).

Part (d) provides a method for him, via his club, to get his non standard design tested.

Re Rocket, I am sure that they would be a succesful design, and have seen one built by a Canvey club member, running well.

He used a scale covered coach to drive from, reaching over the tiny tender.

Did not Martin Evans produce a 1/8 scale drawing of Rocket, although not as a working model.

regards

Brian B

[Colin GParticipant @coling]

Terry, have you seen my for sale add on this site for rocket plans?

Very comprehensive plans, but do not think that they are available any more from the science museum.

Colin

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

So if someone produces a totally rubbish design for an unorthodox boiler and gets the design published in a magazine and then builds the boiler himself to his own published design it gets a free ride through the test procedure and no questions asked by the boiler inspector ???

[nigel jones 5Participant @nigeljones5]

OK – back to the post, I have a good set of 3 1/2" drawings for Rocket, and had intended to build it 71/4 gauge. Plan was simply to times all dims by 2 and accommodate 1/8" in the wheel design to be wide enough. I know theses a bit more to it than that but cant see any real issue….boiler would have to be redesigned but thats a very easy one, especially with it being in two parts. I might even have a go at it but couldnt work out how to make the front wheels??

[jason moore 1Participant @jasonmoore1]

Martin Evans did indeed produce drawings for Rocket,not for a working model though as the previous post has said. These are still available from Myhobbystore and Blackgates i believe.

Fizzy i have been toying with the idea of making the front wheels like the full size versions ie an iron hub with wooden spokes and felloes all held together by a steel tyre shrunk on. I have never before tried this sort of thing so i am sure some of our wheelwright friends out there could advise better than me.

Michael which test procedure are you refering to? The only tests i am aware any model boiler has to pass are the 2x hydraulic test and the steam test to check the safety valves etc. These would of course have to be completed to the boiler inspectors satisfaction, the same as for all newly constructed boilers.

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