1:8 Scale Packard Merlin V1650-7

[zibbit]

On 05/10/2023 at 01:14, Malc2 said:

 

Oohh - Clerget, tell us more!

What scale is it?

 

Malc.

I won't muddle up this thread with replies about another build. However to answer your question, 1:16 as a rotating replacement for a Artesania Latina Sopwith Camel, and 1:10 as a cutaway/rotating/standalone display. TBH the model could be any size up to 1:1 without loosing resolution cause that's what the original model size is.  Here's the build thread if you'd like to see a little bit more.  

 

Thank you Twobad for sharing your exposure settings.. I just received 1L of 12K resin in the mail; so, I'm curious to see how the Elegoo 8K compares to the Phrozen 8K resin. My printer has the same screen, similar design lift arm, and same ACF as your Mighty 12K. I'm excited to see what the Saturn 3 Ultra can print.

 

[kev67]

Totally amazing, I have dabbled in CAD using Rhino 7 but nothing to this degree, you must have a background experience already in using the software to create the artwork, as I know from my experience it is not an easy process to fully understand

[Twobad]

10 hours ago, kev67 said:

Totally amazing, I have dabbled in CAD using Rhino 7 but nothing to this degree, you must have a background experience already in using the software to create the artwork, as I know from my experience it is not an easy process to fully understand

Thank you.

 

As I mentioned briefly, I've been messing with CAD since the late 80s onward, but I've never done it professionally as I was an aerospace design engineer, not a draughtsman. We produced the schematics which the professionals in the Drawing Office then turned into proper designs/models conforming to the relevant ISO Standards etc. I have however, been messing about with CAD that long as I managed to blag access to the Drawing Office's CAD system to play with it and use it for little jobs.

Hence, I'm self taught, but have been doing full-blown 3D modelling on a hobby basis for over a decade. This probably means that the structure and organisation of my models would make the professionals blanch. I do know about Work Breakdown Structures, Drawing Trees etc. but the models are just for me and life is too short for full DEF STAN compliant stuff. I do however apply quite strict configuration control on my models (issue numbers etc) or you can get in a hell of a mess.

Edited October 11, 2023 by Twobad
Spelling

[zibbit]

4 hours ago, Twobad said:

Thank you.

 

As I mentioned briefly, I've been messing with CAD since the late 80s onward, but I've never done it professionally as I was an aerospace design engineer, not a draughtsman. We produced the schematics which the professionals in the Drawing Office then turned into proper designs/models conforming to the relevant ISO Standards etc. I have however, been messing about with CAD that long as I managed to blag access to the Drawing Office's CAD system to play with it and use it for little jobs.

Hence, I'm self taught, but have been doing full-blown 3D modelling on a hobby basis for over a decade. This probably means that the structure and organisation of my models would make the professionals blanche. I do know about Work Breakdown Structures, Drawing Trees etc. but the models are just for me and life is too short for full DEF STAN compliant stuff. I do however apply quite strict configuration control on my models (issue numbers etc) or you can get in a hell of a mess.

 

I'd say the stuff you're doing in CAD is to a lot higher standard than what an average "hobbyist" might achieve. In my eyes, I can clearly tell you have a background in design because of how you've built the model. Out of curiosity, what program are you using?

 

I retired from the RCAF as a aircraft maintainer on the CF-188 and CH-124. Now I'm working as a mechanical engineering technologist in the aviation industry. Primarily I'm designing everything in Solidworks.

[Twobad]

1 hour ago, zibbit said:

 

I'd say the stuff you're doing in CAD is to a lot higher standard than what an average "hobbyist" might achieve. In my eyes, I can clearly tell you have a background in design because of how you've built the model. Out of curiosity, what program are you using?

 

I retired from the RCAF as a aircraft maintainer on the CF-188 and CH-124. Now I'm working as a mechanical engineering technologist in the aviation industry. Primarily I'm designing everything in Solidworks.

The Merlin has been done in AutoCAD, but the renders have been done in Fusion 360 because it is better at that. I've also created all the 3D print STL files in F360 as the standard max resolution in ACAD isn't that good and it's a real faff messing with the system variables to improve that.

I'm medically retired now, but I used to be the senior engineer looking after the BAe Hawk cockpit equipment (hence my avatar). After that I moved into the project management team running the development test aircraft and ground rigs.

 

I need to move away from AutoCAD as my access to it will end soon, and I'm not stumping up £1600 a year for my own private licence. I have just bought a 'Makers' Solidworks licence, but haven't really got started with it yet. I'm not relishing the transition.

Edited October 11, 2023 by Twobad

[Malc2]

Your Merlin is really impresssive, the attention to detail is superb.

I lookforward to each new update!

 

Malc.

[Bozothenutter]

Did I mention I really, really love oily bits?

This looks wonderful !

[Twobad]

2 hours ago, Bozothenutter said:

Did I mention I really, really love oily bits?

This looks wonderful !

Well, the Merlin was nothing if not oily!

[scott_t]

truly amazing work

[Twobad]

A bit of decent progress on the model over the last couple of days. It's nice to see some the parts becoming how I imagined them at the start of all this.

The North-East magnetos are assembled, painted and fitted. I might be a bit previous on the latter as I'm still not certain how I'm going to do the braided conduits that carry the HT cable bundles away from them.

 

 

 

All the effort on the manufacturer's label hardly seems worth it now. There's quite a few other parts that are going on top and in front of it too before the model is done. By then it'll be lost in the dark. Incidentally, the black cylinder with the green connector in the foreground is the solenoid that changes the gearing for the 2 speed supercharger.

 

 

 

The cam drive cover is finally in place. It's a fairly trivial thing buried deep in the model but it has given me endless grief. It was very difficult to get clear pictures of it, the Packard drawings were less than lucid, and then I forget to add it to the print batch of all the supercharger related parts so it necessitated a special print run. It's on now though. 

 

 

 

The main coolant pump is complete too. Interesting thing to draw up. Another pair of horrid volutes like the supercharger and aftercooler coolant pump. The two volutes are also not the same, and have to be drawn individually. I wanted to get a scale wall thickness to the open end of the coolant inlet (0.3mm), but that would've made the part very delicate indeed. Hence, I cheated a little as the outside of the pipe is circular and the inner is a cone. The wall thickness changes to 1mm thick by the time it gets to the flange and means the part is actually quite robust. Don't drop it open end down though!

 

 

 

The starter motor has also been completed. This hasn't come out as well as I'd hoped to be honest. The Alclad "Steel" is too dark for my liking and the satin lacquer has come out too close to the gloss end of the spectrum. I'm still pondering making a decal for the manufacturer's plate, but it's a complex thing with a lot of tiny detail that might not survive scaling down.

 

 

 

 

 

Here's the coolant pump in situ on the bottom of the Wheelcase, below the fuel pump, with the starter motor lurking behind. The cold coolant feeds up to the cylinder assemblies emerge from the blanked off hole in the picture. I'll fit those when the cylinder assembles are in place.

 

 

 

And on the other side of the Wheelcase is the starter motor. The circular blanking plate directly above the motor hides the manual cranking input. On earlier versions of the Merlin there is actually a socket to put the crank handle into, but by this stage of the war it was realised that the feature was hardly used. I wouldn't relish hand cranking a V12 27L engine with supercharger attached to add to the thrill.

 

 

 

That's it for this update. Lots of fiddly pipework to paint and fit in the next one...

 

 

[Pete in Lincs]

All those lovely nuts and studs. Where's me socket set?

It really is a thing of beauty. (Did I say that before?) I'm sure there'd be a commercial market for these. But I imagine the price would not be small.

I've seen a few pictures of Hurricanes being hand cranked. But never a Spitfire. It was common on Luftwaffe Aircraft though. (And Panzers)

[Twobad]

3 hours ago, Pete in Lincs said:

All those lovely nuts and studs. Where's me socket set?

It really is a thing of beauty. (Did I say that before?) I'm sure there'd be a commercial market for these. But I imagine the price would not be small.

I've seen a few pictures of Hurricanes being hand cranked. But never a Spitfire. It was common on Luftwaffe Aircraft though. (And Panzers)

I need to go around with the pin wash to back a lot of the nuts off a bit. Though, if you look at the Smithsonian engine, the nuts and bolts are quite stark and out there. I assume they are zinc or cad plated.

 

I'll hoick the CAD design around a few people and see if anyone is interested in taking it further*. I might do the odd kit for people who really, really want them, but it's 9 days of printing, about £70 of resin and a lot of work to remove supports, pack the thing and ship. I'm not that interested in doing that, and no it wouldn't be cheap. People would also need to be prepared to look at the rendered images to work out what bolts go where because there will be no written instructions.

 

On the last item: I read a Battle of Britain pilot's autobiog (Can't remember who, I have a bookshelf of them). A friend of one of the pilots, who swore he'd never work for him, was cranking a Merlin to get it started. It was taking a while and he was working up a distinct sweat. He looked up at the pilot to see what was wrong because the engine hadn't even tried to fire after an age of cranking. He was met by the grinning face of his mate in the cockpit. The airman requested, with a degree of asperity, that the pilot press the bloody start button.

 

 

* If anyone knows someone who might be interested, message me.

[Dave Swindell]

12 hours ago, Pete in Lincs said:

I've seen a few pictures of Hurricanes being hand cranked. But never a Spitfire.

Probably because it wasn't done very often - there was a warning label below the hand cranking socket that read:-

 

Hand turning gear for maintenance only.

If used for emergency starting aircraftsman must have rope from his waist to the undercarriage to prevent him falling into the airscrew

 

 

[Nick L]

Beautiful work! WRT the hidden data plate on the magnetos, at least you'll know it's there even if no one else does...

 

 

Edited October 15, 2023 by Nick L

[Eivind Lunde]

Fantastic work!
But didn't the Packard built Merlin's have fewer bolts on the back of the engine due to Packard trying to make it quicker to build and easier to maintain? I read somewhere that they reduced the amount of bolts to half around the auxiliary connection end, but made them thicker to compensate. 
I'm not saying yours is wrong, only trying to get the story verified by someone who obviously know.  

[Twobad]

1 hour ago, Eivind Lunde said:

Fantastic work!
But didn't the Packard built Merlin's have fewer bolts on the back of the engine due to Packard trying to make it quicker to build and easier to maintain? I read somewhere that they reduced the amount of bolts to half around the auxiliary connection end, but made them thicker to compensate. 
I'm not saying yours is wrong, only trying to get the story verified by someone who obviously know.  

Thank you for the nice words, and everyone else for that matter.

 

I don't know is the short answer to your question. I'm by no means an expert on Merlin minutiae. However, as far as I know Packard only redefined the engineering tolerances in the design to ensure the interchangability between parts rather than having to fettle individual fittings to suit a particular engine.  One major change that was introduced at Packard was the incorporation of the 2 part block design. That however was actually a Rolls-Royce design improvement that they hadn't had time to introduce on their production line due pressing wartime demands for engines. Packard, starting from fresh were able to include it from the beginning and hence, introduced it first.

If you look at the last picture in my post above, there is one row of studs and nuts holding the intermediate and rear supercharger castings together. No bolts there, but that is because it would have been very difficult to get at the rear of the bolts. The design also uses quite a few captive circular headed bolts with flats on them. Again, they are visible in the last pic of my post above. They mate with machined lugs on the castings meaning there is no need to put a spanner on them when tightening them. I don't think they are peculiar to the Packard engines though.

 

 

One thing I can say is that the later Merlins have a removable rear cover on the superchargers which the earlier Merlin III didn't. I've no idea why the change was introduced, but it must make casting easier and access to the accelerator pump injector.

Contrast the Merlin III engine's rear, single stage, supercharger with the later 2 stage designs which actually have more bolts, not less.

 

 

 

 

 

[Twobad]

3 hours ago, Nick L said:

Beautiful work! WRT the hidden data plate on the magnetos, at least you'll know it's there even if no one else does...

 

 

There is that, and I am a believer of the fact that the eye takes in more than we are aware of.

[k5054nz]

I volunteer on a P-40 restoration and several of the team use Fusion360 - we have a CNC machine and one of the team has a 3D printer for hobby use - and I've been increasingly curious to learn it. I'd love to build an Allison V1710 in a large scale and this is seriously inspirational stuff. But I know: baby steps!!!

[Twobad]

 

I've been gently pottering along on the Merlin with no major crises or set backs. All of the pipework is painted and about half of it installed on the engine. The things are precariously delicate though.

 

 

 

I've also got around to finishing off the accelerator pump that fits on the top of the rear of the supercharger casing. One thing that does surprise me is the diameter of the fuel feed coming up from the carburettor. Half inch! How much fuel does this thing use in extremis?

 

 

 

Here it is installed on the supercharger. The oil feed pipe to the supercharger rear bearings and the silver fuel pipe are only mocked up in position. I'll fit those properly a bit later on when the carb and boost control mechanisms are in place.

 

 

 

These are the oil feeds to the camshafts. I really want to get the cylinder assemblies on because these things are a bit too vulnerable at the moment.

 

 

 

In addition to the pipework and accelerator pump I've also been painting and assembling sundry other parts in prep for the great assembly phase.

 

Top, in silver, are the Ki-Gas priming pipes which fit on top of the inlet manifold. I always wondered what they used for priming the Merlins, especially as the basic fuel was 100 octane or more. Whatever it was must've been very volatile. I finally got my answer the other day when I was looking at some of the P-51D drawings and noticed a pipe from the cockpit pump labelled "Propane feed". No wonder it was volatile stuff!

 

Below the priming pipes are the main coolant feeds, cam drives and at the bottom the aftercooler coolant feed pipe which connects the pump to the header tank on the aftercooler.

 

 

 

I've made a bit of progress on the ignition conduits too, but they aren't complete yet. I've seen these in all sorts of finishes on the various museum engines and the ones in private hands. I didn't want them to be yet another black pipe on a black background and I did consider finishing them in brass, but that felt a bit blingy, However, I had noticed the ones on the engine in the Smithsonian Museum are an odd green/grey. That prompted me to go and check the finish called up on the actual Packard drawings (as I'd assumed they were black tbh). The finish is actually PM1422 Engine Grey. I wonder why these parts are grey? They're the only things on the engine that aren't black or plated.

 

 

 

I also had a bit of a mess with the exhausts. Alclad's "Exhaust Manifold", while a lovely colour, didn't feel very exhaust like to me. I've had a go a titivating them a little with some Tamiya Clear blue on the base, and some Deck Tan brushed over with Tamiya Weather Master Soot at the exit. It has improved things a bit, but I feel some matt varnish coming on.

 

 

 

I decided life was too short to be painting all the bolts and fittings on the carb in-situ. Hence, a happy day (not so much) was spent breaking the thing down into manageable parts, making clearance holes for all the bolts and creating a bolt set. The latter sub-divided into those which are silver and those which are brass. Hopefully the little brass subset will snap cleanly off the main part to allow separate painting. I've also doubled or tripled up on the most delicate parts as it's inevitable that I will break some. In fact I've already damaged one bit removing some of the supports prior to UV curing of the prints.

 

 

Painting and assembling the carb will be the next bit of fun...

[Pete in Lincs]

Howmuch fuel does this thing use in extremis?

I'm sure I read ages ago, around a gallon every two minutes on boost. 

Never heard of propane being used. Geoffrey Wellum wrote, six pumps on the kigas from cold.

[k5054nz]

Magnificent.

[The west wing]

Amazing build, the attention to detail is fantastic. I notice you have even used the correct type of Jubilee clip with the early round head rather than the modern hexagonal head!

 

 

[Twobad]

9 hours ago, The west wing said:

Amazing build, the attention to detail is fantastic. I notice you have even used the correct type of Jubilee clip with the early round head rather than the modern hexagonal head!

 

 

I just want it to be right. If it's not it irritates me until it is. In fact I've just noticed an error in the exhaust ignition leads today, so they are all getting redrawn and re-printed.

 

Overall though, I've just followed the Packard drawings all the way. The only parts where I've been a bit creative, and had to rely on photos, are the bought in components such as the carburettor and generator. Even there, Packard have interface drawings which give dimensions for all of the connection points.

 

I have increased thicknesses of parts in a few areas because they just won't print at 1:8 scale. I'm beginning to wish I'd done it in a few others too, as the parts are exceeding fragile and brittle.

[Klaasdebouwer]

Simply stunning. Amazing project that would make the old wizzard proud.

[Twobad]

 

The Bendix-Stromberg carb mini kit has been assembled and went quite well. However, in my excitement to fit it to the supercharger I forgot to take any photographs of it on its own. Here it is fitted in place. I think I'm going to have to knock up a decal for the thing though, as the large blank oval looks a bit conspicuous and out of place.

 

 

 

 

Fitting the carb has also allowed me to add the pipework up to the accelerator pump. It's nice to have something that adds a bit of variety to the colours, even if it's only very, very slightly different.

 

 

 

 

 

The other big advance is that I've finally got around to fitting the cylinder assemblies to the crankcases. They went on without any great drama and have added some much needed weight at the front of the engine stand. The C of G was getting a bit close to the rear legs tbh.

 

 

 

You can see why dropping a spark plug down the gap was seen as such a faux pas, especially as most of the V is filled with the inlet manifold.

 

 

 

Having the cylinders in place means that I've been able to install the feed pipes from the coolant pump. I'm really quite pleased with how the connectors have come out. It was worth the effort drawing them up.

 

 

 

Fitting the cam shaft drives at the rear of the cylinder assembles did not prove as easy as hoped. They're in now, but they fit where they touch. Thankfully this indiscretion will be hidden deep within the model when it's finished.

 

 

 

 

I couldn't resist a trial fit of the inlet manifold and aftercooler. I need to finish the ignition HT leads before these bits can go in permanently.

 

 

Not sure what's next... HT leads or the Automatic Boost Control assemblies. Probably the leads, as some of the boost control bits are hellishly fragile and vulnerable. They will be begging to get broken off.