A powered Armstrong Whitworth D9 - plans included.

[sleeper]

Thanks Beatty 

It certainly does, is this project going to be the subject of a separate thread? I'll be interested in how it develops so post a link on here if anything changes.

[JCL]

Hi Alan, its looking brilliant so far, and of course, you are getting along so quickly it's untrue!

[Beatty 139]

Thanks Jason

The only reason it's making quick progress is thanks to you doing the thinking first on how to make the assembly.

 

The jobs for this evening is to cut the bonnet nose internal formers out and fix them in place.

 

Having now got my copy of the AW book back and carefully studying the photos in it you can make out quite a few changes to D9 over her short working career, I think that my model will reflect the loco towards the ends of it's days with the LNER with clasp brakes on the pony truck, steps on the cab ends and recessed louvre panel on the body side where the exhausters were modified, just a shame we have no clear roof photos.

[JCL]

Yep, the roof was the hardest bit to work out as there's not much to go on. This post has my assumptions based on photos of other units amd hoping they didn't reinvent the wheel too much http://www.rmweb.co.uk/community/index.php?/topic/83896-a-powered-armstrong-whitworth-d9-plans-included/?p=1428297

[Beatty 139]

What with a funeral and the G1MRA AGM this week I haven't had a lot of chance to make much progress this week on the 'Universal'

 

 

I have made up the inner frame for the auxiliary engine bonnet, and also made up the 0.5mm overlay for that cab end.

 

I started cutting the louvers out from 10thou plastikard on the cameo and putting these in place, i have stated thinning them down on the top edges to a proper profile, I am sure that by the time I do them all it will have driven me to drink!

 

 

At the AGM I manage to source the wheel castings for drivers and bogie wheels, so they will be a turning job over the next week or so, and I have sourced the traction motors and radio equipment, some nice lost wax LNER loco lamps, I was hoping to get some lost wax buffers but the trader who used to do them has ceased trading so that will be another turning job, a nice distraction from scraping louvers to profile!

 

I think this weeks main aim will be to make up the formers for the dome cab ends and main roof supports, I have ordered a low speed geared motor for the cooler group fan so I am hoping the slow boat form china will bring it soon so I can work it in to the loco.

[JCL]

It's looking fantastic! And huge. Did I say huge before? Do you think you'll be able to do some video of it moving when you get to the end?

[Beatty 139]

Huge is a relative term and for G1 it's quite a modest sized loco, but it does fill the loading gauge so should have a presence. I have a interwar period LNER goods set that I normally run with my live steam J27 the Universal should look well on them.

I am going to have a go at having it running for Warley show, but I might not get it done due to the delivery on the traction motors.

Back onto the issue of size I don't think I could go back down the scales now but you do find yourself worrying about things that are passed over in the smaller scales because they are there, it's a hard choice to decide what leave out sometimes.

[JCL]

A quick question, but what's your views on the shape of the fans?

[Beatty 139]

The fan shape is an question that I have given quite a lot of thought on, and I have some insite on with my professional job as a HVAC design engineer.

 

AW were designing most of it's loco for harsh environments, so to achieve the heat disapation from the cooler groups would have required either larger surface area, or greater airflow, even with the larger loading gauges the cooler groups from studying the images don't get significantly larger, so they must have gone for the increases air flow.

There is then the trade off that with that greater air flow comes increased restance so the pressure increases, add to this filtration as crops up time and time again and the obscration factor for both the filters and cooling elements and with an Axial fan you start coming up with some big numbers for input power and the design ends up like a jet engine the compressor section of which is an Axial fan, and which the AW locos for export all look like they have jet engine poking out of the roof.

So going back to D9 we have a loco designed for home Market operating in modest climate and a 800 HP power unit two cooler groups of very generous size for the duty (look at a BR class 73 similar HP but a cooler group half the size) if we say we need dissipate the waste heat from 400hp (each side) go and compare that against a modern lorry tractor unit, D9 is massive in comparison, so that takes us back to air flow required, low volume air flow, low resistance through the radiator elements, lower pressures needed less HP to drive the fan, simpler unit especially when we consider it's 5' diameter, back to how the designers would have thought simple bladed axial fan, something that were much more used to for the UK, we can see that D9 had no inlet guidance cowl on the roof so I suspect the fan boss would be the same it wouldn't need to be for the air flow duty and pressures it had to accheve

[ozzyo]

The fan shape is an question that I have given quite a lot of thought on, and I have some insite on with my professional job as a HVAC design engineer.

 

 we can see that D9 had no inlet guidance cowl on the roof so I suspect the fan boss would be the same it wouldn't need to be for the air flow duty and pressures it had to accheve

 

For some reason I had always thought that the inlet for the air was in the sides of the loco and the exhaust air through the roof (hot air rising and all that).

 

Think of a class 40 after a hard run in the rain radiator fan running hard sucking a load of rain in and forcing it out of the sides and then running into a platform!!!!!

 

Just my thoughts

 

OzzyO. 

[Beatty 139]

Hi OzzyO

AW had a thing about filtration of the air, so under the fan there is a filter bank under the fan in the case of the universal, I presume the idea was to keep the elements clear from build up on them.

If you make them work the otherway round any dust, brake dust etc would get dragged straight into the cooler group elements and they would soon block.

[Buhar]

A quick question, but what's your views on the shape of the fans?

I think you have an answer there, Jason!!  And the reason why.  And the wherefore.  And the physics.  And the type of dust you need to weather it with.

[BernardTPM]

Though I've never found a photo of the fan and associated boss for the UK Universal where the boss is visible on other AW locos it does appear to be like the spinner of an aircraft propeller. On the basis that the cooling units all had a great deal of similarity it would seem reasonable to assume the fans would appear similar too. References in the Armstrong Whitworth diesel book:

1. p13 drawing of UE1 & 2

2. pp19 & 20 photos of 1700hp mobile power house

3. p57 drawing of UE3-5

4. p64 photo CM210

5. pp105 &105 photos of Ceylon/Argentina export Universals

6. p108 DT51 1200hp

7. p133 DT19 'Cometa'

[david.hill64]

For some reason I had always thought that the inlet for the air was in the sides of the loco and the exhaust air through the roof (hot air rising and all that).

 

Think of a class 40 after a hard run in the rain radiator fan running hard sucking a load of rain in and forcing it out of the sides and then running into a platform!!!!!

 

Just my thoughts

 

OzzyO. 

On a couple of test runs I had to pass through the engine compartment of an HST power car: the noise next to the engine was incredible, but the most uncomfortable bit was passing the cooler group. The air intake from the sides was so strong as to make you believe you were going to be drawn into the radiator bank!

[Beatty 139]

I should say that I will make the fan boss, coned but not protruding above the roof line like most AW locos, I do Agree with Bernard, if it was a pattern that AW had in the foundry I doubt they would change it. What they would change is the pitch angle of the blades as that is what sets the performance.

 

It could be that AW cooling systems air path went sides to roof and the notes on the drawings about filters are a red herring but then I guess they had no convention to work to and were inventing the wheel as such! It's a shame that no set of instruction manuals have turned up in some distant railways office as that would offer so much more insight into the practices, I haven't even ever seen a cab interior photo anywhere that you would have expected promoting how improved driving conditions were so it's all guess work for me! I added porthole windows into the bulkhead doors just on a guess they would have had some sort of vision panel, but who knows!

[Beatty 139]

Work with a chap who when he first qualified as an electrical Enginner moved over to Canada for a few years on CN before coming back to the UK so I asked him how did the cooling work, from his memory it blows in from the top and out through the sides. It's one of the little details we don't think about much as modellers! Back to work lunch over!

[cheesysmith]

Uk diesels have always blown from the top down and out through the sides. It is why from above you can see the fan, the fan is before the radiator, blowing the air through them. On the GM imports and the 60s, the opposite is true, so from above all you see ae the radiators, as the fan is mounted below blowing up. I think BR specified this on purpose to avoid debris being sucked up into the radiators, and due to the higher platforms we have to avoid any item of the public being sucked against them when walking past them.

 

The American stuff have blown the other way, with the ex SP tunnel motors being a good example, to make sure that the cooler air is blown through the radiators, instead of the hot air near the roof in tunnels.

[JCL]

I honestly didn't think I'd find out this much about fans. It's been very interesting.

[Beatty 139]

Well I haven't been just thinking about fans, and the motor for it hasn't turned up yet so that's still for another day.

 

so other than applying the 10 thou plasikard louvers leaving them over night then scraping them back to 30 degree tapper I have started to form the cab domes

 

 

The domes have been formed from 1.5mm sections layered up to form the outline of the profile.

 

I have put a first layer of filler in and cleaned it back and I am reasonably happy with the shape of the domes. Its also been time to think about making the Universal move, wheels are in the process of being machined then they are going to the chap who makes up the traction motor units (3 like the real one). The first thing I have done is cut a 3mm aluminum plate to fit the bottom of the loco end to end this will the the structural bed plate for the loco and should also provide a good heat sink for the speed controller. Onto this plate will be screwed 4 10mm x 1.5 aluminum angle sections, including at the rear of the buffer beams.

 

The outside faces of the frames shall be in 1.5mm Rowmark but for structural  strength as they have to carry the bearings for the wheel sets etc, the inner frame layer has been cut from 1.5mm aluminum. I cheated a little cutting these out instead of riveting them together to cut them as a pair, they were 'super glued' then just warmed to split them apart after.

 

I have made the inner frame about 0.5mm less than the outer ones so they don't look too thick when overlaid, save measuring they had a quick coat of rattle can black then dropped onto the laser to mark them out.

 

 

I then drilled and pierced them out as normal.

 

 

My new stock of Rowmark is due Monday so that should see the outside beading going on the body.

 

 

 

 

[69843]

All I can say is wow.

 

This is amazing Beatty 139!

[Beatty 139]

Thanks for that, it's really a bit of light relief in-between building my next G1 live steam, and developing new stuff for my Woodbury Models brand. I was so taken by Jason's post that I wanted to give it a go, and have something unique that suits my intrest in pioneer locomotives, a chap has built LMS 10000 & 10001 in G1 it could be an intresting day if we have them running as well as the AW Universal at the same time. Although something keeps telling me the Fell diesel should come next! It's a Shame more people don't give G1 a go as it's a great scale to model in and no more expensive than 0 Gauge if you scratch build, plenty of friendly people and clubs with tracks to run on, it just needs a bit more of a push towards railway modelling at times, as it is very much the mixing point between railway modelling and model engineering.

[BR(W)]

Uk diesels have always blown from the top down and out through the sides. It is why from above you can see the fan, the fan is before the radiator, blowing the air through them. On the GM imports and the 60s, the opposite is true, so from above all you see ae the radiators, as the fan is mounted below blowing up. I think BR specified this on purpose to avoid debris being sucked up into the radiators, and due to the higher platforms we have to avoid any item of the public being sucked against them when walking past them.

 

The American stuff have blown the other way, with the ex SP tunnel motors being a good example, to make sure that the cooler air is blown through the radiators, instead of the hot air near the roof in tunnels.

An opening apology for continuing the meanderings off-topic, but, crikey! a post at once seeming both peremptory and perfunctory: declaimed with the finality of unchallengeable authority, yet citing not one example.

 

Now, as intimated earlier, I have always believed that BR diesels drew in air from the bodysides or cantrails, and exhausted upwards, directly from the roof fan/s.

 

So, herewith two extracts to support my view, the first from the era of Pilot Scheme and first generation production machines:

 

"In most locomotives the radiator is in two sections, one on each side of the body, and air is drawn inwards by a fan from outside the locomotive and exhausted upwards through the roof. Radiator fans may be driven mechanically, electrically, or by oil pressure..."

 

          'INSIDE a diesel locomotive' (sic), Basil K. Cooper, Ian Allan 1964. Chapter 1, 'How the diesel engine works' (sic), p.15.

 

And the second from a technical review of BR's last design:

 

"At the No. 1 end is the third compartment housing the diesel engine radiators and cooling fans...

"Unfiltered air for the radiators is drawn through the bodysides by two motor-driven roof-mounted 'pusher' fans, and is expelled through the roof after passing through the cooler panels."

 

          'BR EQUIPMENT 2', David Gibbons, Ian Allan 1990. Chapter 'The New Class 60 Heavy Freight Diesel Locomotive', p.92.

 

I could also mention the cost-benefit study carried out by BR into the redesign of the Class 25 bodysides to avoid track detritus and brake dust being drawn in through the bodyside grilles - but I shan't.

 

Finally, a closing apology if I have misinterpreted anything, or am plainly wrong. But may I please ask for any counter-arguments to be supported by evidence so that we may all learn.

 

Thank you.

 

Cheers,

 

BR(W).

[Beatty 139]

It's all of intrest, in the case of D9 Armstrong Whitworth they didn't have anything to follow so were writing there own book on how to make a diesel locomotive. It's such shame so little has survived.

What you say BR(W) makes sense for main line British loco as unlike the AW locos they have no inlet cowling on the roof to guide the air into the fan. Getting back to the AW Universal, D9's roof is going to have to be a best guess and my model will be much like JCL's as I don't think anything better is going to come to light about AW cooling

[JCL]

Very true. I don't have the book to hand, but remember reading the frustration of the author about the lack of information. I'm sure Bernard's references in the same book will help. I'm really enjoying your build.

[sleeper]

There's some interesting use of alternative materials in this thread. Aluminium, in the same vein as my 'beer can' roofs.

Beatty could you elaborate on your drilling and 'piercing' method of producing the inner frames for me please.

 

Thanks