Author Topic: Model Mechanics - 'Eagle' drawings  (Read 4617 times)

0 Members and 1 Guest are viewing this topic.

Offline IanT

  • G3 Society Member
  • ***
  • Posts: 568
Model Mechanics - 'Eagle' drawings
« on: October 10, 2009, 10:10:12 AM »
The 'Model Engineer' website has just placed the first set of PDF copies of 'Model Mechanics' on their website for download.

From Issue 3 Vol 1 - onwards you will find a description of 'Eagle' a 2 1/2" gauge loco design by Martin Evans which he describes as a simple beginners engine. It's a outside twin cylinder 4-4-0 coal-fired tender engine based on the GNR(I) original. Roger M has run his version of this engine at GTGs over the years and it is a handsome engine which runs as well as it looks.

The building instructions are pretty comprehensive - so it is a useful read for anyone contemplating building a small live stream engine. Martin also makes a good case for tackling a 4-4-0 tender engine first - as compared to a smaller design - claiming that there is not too much extra work involved (over a 0-4-0) and that the resulting loco is more capable and satisfying to drive/own.

Regards,

Ian T
Nothing's ever Easy - At least the first time around.

Offline Cabbage

  • Forum Technical Adviser
  • ****
  • Posts: 688
Re: Model Mechanics - 'Eagle' drawings
« Reply #1 on: October 10, 2009, 08:35:58 PM »
A URL would be useful -because I cannot find it!

regards

ralph

Offline IanT

  • G3 Society Member
  • ***
  • Posts: 568
Re: Model Mechanics - 'Eagle' drawings
« Reply #2 on: October 11, 2009, 03:38:41 PM »
Nothing's ever Easy - At least the first time around.

Offline Kalinowski

  • G3 Venturer
  • ****
  • Posts: 84
Re: Model Mechanics - 'Eagle' drawings
« Reply #3 on: October 12, 2009, 03:06:03 PM »
Hi Ian, Yes the Eagle is a relatively simple design and the 2.5 chaps supply all the castings needed to build one.

The "interesting" and positive point about the choice of design is that outside cylinder locos are "relatively" easier and quicker to build than inside cylinder types because ( cylinder blocks a bit easier to make, no crank axle, easier valve gear construction, quartering of drivers).

The "problem" point is that there were relatively few UK pre grouping outside cylinder tender engine 4-4-0s or 2-4-0 or Atlantics with inside valve gear. I have explored this for some years, for example - the GNI Eagle; LSWR Adams T3/T6 and X3/X6: Beatie 2-4-0s; Midland compound, Atlantic LBSCR and GNR, Brighton K, all the post Dean Churchward tender engines are 4-6-0.

By contrast with the UK the vast majority of designs overseas between 1860 and 1900 are outside cylinder types i.e. France, Italy, Norway, Sweden, Denmark, Holland - many of which ironically, were supplied by British manufacturers.  Oh well, proves something - not sure what!

Offline MikeWilliams

  • G3 Forum Moderator
  • *****
  • Posts: 941
Re: Model Mechanics - 'Eagle' drawings
« Reply #4 on: October 12, 2009, 07:35:18 PM »
Don't forget the largest pre-Grouping company Peter - LNWR.  The 80 Webb 4-4-0 compounds were all built with outside cylinders and inside valvegear.  They were very attractive too.  OK, they were 4-cylinder so had inside cylinders too.

Mike

Offline IanT

  • G3 Society Member
  • ***
  • Posts: 568
Re: Model Mechanics - 'Eagle' drawings
« Reply #5 on: October 13, 2009, 10:16:38 AM »
And the M&GN had both the Johnsons and the Peacocks with 4-4-0 outside cylinder arrangements. Both were very attractive tender engines. It's a very simple set-up for a first model and has much to commend it.

As Pete says - inside cylinders and any associated valve gear involve all sorts of complications (both to build & to set-up correctly) and wouldn't be my immediate choice for a 'first' live steam engine. Different thing altogether if you are building a battery electric - as the 'build' is then actually simpler with all the 'works' hidden "inside".
Nothing's ever Easy - At least the first time around.

Offline Kalinowski

  • G3 Venturer
  • ****
  • Posts: 84
Re: Model Mechanics - 'Eagle' drawings
« Reply #6 on: October 13, 2009, 05:02:50 PM »
Mike, no offence meant to LNWR enthusiast I confess - I just forgot!
 However, in terms of the huge volumes of LNWR locomotives built the famous and very elegant Precedent 2-4-0 family and the earlier variants, Precursor 4-4-0, the Experiment 4-6-0 family, the variety of 2-4-0 and 2-4-2 tanks and 4-4-2 they were all inside cylinder.

regs PK

Offline IanT

  • G3 Society Member
  • ***
  • Posts: 568
Re: Model Mechanics - 'Eagle' drawings
« Reply #7 on: October 19, 2009, 10:47:02 AM »
Returning to the original thread topic!  :)

I've noticed that Issues 5-10 of Model Mechanics are available to ME/MEW "subscribers" only.

Since I am a subscriber - it's not a problem for me - but if you are not a subscriber I'm afraid you will not be able to see them. However, if any G3 Society Member (fully paid-up of course - you have remembered to renew this year haven't you?) is interested in 'Eagle' and would like to look at these plans, then please contact me directly and I will help out (I have the original MM magazines and can also download the PDFs - so I'm sure we can figure something out).

Obviously this offer is for 'personal use' only.

Regards,  Ian T   8)
Nothing's ever Easy - At least the first time around.

Offline bambuko

  • Group A Forum Member
  • *
  • Posts: 23
Re: Model Mechanics - 'Eagle' drawings
« Reply #8 on: January 08, 2010, 06:12:26 PM »
Staying on topic  ;D
As is usual with old designs, sometimes things don't add up, so just in case somebody else (and in particular the beginner for whom this design is meant) is thinking about building to these plans, I have just spotted first error:
Horn opening in the main frame, shown as 3/4" wide should actually be 7/8" wide to fit with horn and axlebox, as drawn.
If I find anymore, I will add them here.
BTW, this is my first post on this excellent forum and you guys are to be congratulated both on it's quality and open minded policy of welcoming all (not just G3 members).
Chris

Offline Christopher

  • Forum Group A Member
  • Group A Forum Member
  • ***
  • Posts: 31
Re: Model Mechanics - 'Eagle' drawings
« Reply #9 on: January 08, 2010, 06:53:45 PM »
The Association hold a full set of castings for Eagle. Email me on chc@jacom.co.uk

Offline Kalinowski

  • G3 Venturer
  • ****
  • Posts: 84
Re: Model Mechanics - 'Eagle' drawings
« Reply #10 on: January 09, 2010, 12:04:24 PM »
The Eagle is an excellent starter loco, however I found a problem with the cylinder block castings. The loco as a 2.5 design was designed to be a people hauler and as such the clearances are generous. The cylinder casting juts out from the frames so much (appx 6 to 8mm) that it is difficult to machine them such that they are "to scale" for a G3 loco.  The stroke length is OK however.

A better casting to use if you are concerned about scale cosmetic appearance, is the "GNR Single" cylinder block which is spot on and look good, available from the 2.5 Gauge Association - from Chris Cruickshank.

regards and Happy New Year.

Offline croned

  • G3 Society Member
  • Group A Forum Member
  • ***
  • Posts: 18
Re: Model Mechanics - 'Eagle' drawings
« Reply #11 on: January 10, 2010, 11:43:28 AM »
Perhaps the wide cylinder spacings is related to the narrowing of the gauge to 4ft 81/2 ins from the originals 5 ft 3 in. which scales out at just under 71 mm in G3.

Offline bambuko

  • Group A Forum Member
  • *
  • Posts: 23
Re: Model Mechanics - 'Eagle' drawings
« Reply #12 on: January 10, 2010, 05:03:21 PM »
The original was a compound loco, with two outside ones being LP.
If you take original 19" dia and scale it down 1:22,6 it would be .841"
Evans actually made them .750".

Quote
...cylinder casting juts out from the frames so much (appx 6 to 8mm)...
I am not sure I understand you?
Drag and buffer beam are 4 3/4" wide
Frames outside 2 1/8" wide
Cylinder outside from frames 1 3/8
So cylinders on the outside are 4 7/8"
I make it sticking out by 1/16" [1.6mm] both sides - total 1/8" [3.2mm]
Having said all this  ;D I do not disagree with you - it would look better/more proportional with smaller cylinder.

Quote
...2.5 design was designed to be a people hauler and as such the clearances are generous...
Do you mean loading gauge?
Apart from the fact that your usual 2 1/2" design is usually more freelance than scale  :D I thought there very much similar?

BTW, Eagle being freelance version of class V, you might be interested in the last loco built for GNR(I) in 1948.
This is simple (non-compound) 3 cylinder class VS with Walschaert outside (and inside) valve gear.
Much nicer looking as well  :)
It shared most of the with V class,


Chris

Offline croned

  • G3 Society Member
  • Group A Forum Member
  • ***
  • Posts: 18
Re: Model Mechanics - 'Eagle' drawings
« Reply #13 on: January 10, 2010, 06:45:25 PM »
Here in Ireland we run on Broad Gauge track at 5 ft 3 in so the GNR(I) engines would have a wider frame spacing than in the UK. The track gauge could have been even wider. At an early point in the building of Irish railways the gauge question was tackled by a government commission and the official gauge for Ireland was set at 6 ft 2 in. The Ulster Railway the second railway in Ireland to open in 1839 from Belfast to Lisburn was built to this gauge running on a Baulk road similar to the GWR. The Dublin and Drogheda Railway was built to a Gauge of 5 ft 2 in and ultimately would join the Ulster Railway to form the principal trunk route from Belfast to Dublin. A typical Irish dispute followed whereby the official gauge was reset to the current 5 ft 3 in. The Ulster Railway re-gauged in 1848 and went on to join with the Dublin and Drogheda as the two major constituents of the GNR(I) in 1876. The loading gauge is a bit more generous as well with some Park Royal coaches 9 ft 10 in wide with 3 + 2 seating. Tom Ferris's book on the history of Irish railways is recommended.

As most models are designed around Standard gauge there is a compromise which generally means narrower than prototype frame spacing. It is very apparent in OO gauge with many Irish models running on 16.5 mm track rather than the 21 mm a P4 approach would warrant. The compromise tends to be highlighted  by wide wheel splashers. In an ideal world I would like to model a BCDR tank like No 30 in Cultra with its attendand 6 wheel coaches but then what scale and gauge !

The difference in gauge has had a couple of interesting real compromises. The LMS converted two 3F Jinties to 5ft 3 in to run on the NCC and later converted them back again. CIE where a prolific user of BR Mk II stock running on 5 ft 3 in bogies. They also had a series of generator vans built from Mk I stock that have just been disposed off. They have been snapped up by UK preservation groups that have swapped the boggies to bring them back to standard gaguge.

Offline MikeWilliams

  • G3 Forum Moderator
  • *****
  • Posts: 941
Re: Model Mechanics - 'Eagle' drawings
« Reply #14 on: January 10, 2010, 10:11:15 PM »
I didn't realise the prototype Class V was a compound.  Has anyone built a working compound (of any sort) in Gauge 3 at all?  I've never seen one.

Mike