Author Topic: Merlin Engine  (Read 920 times)

Offline Spark-Doctor

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Merlin Engine
« on: July 21, 2019, 02:53:03 PM »
Hi All and thanks for letting me join.

I am a Electrical & Mechanical engineer living on the South coast of the UK. I am getting close to retirement now and have been thinking for a while of what i shall do to occupy my time when the day comes. For a very long time, i have been very interested in the Rolls Royce Merlin engine and recently came across the quarter scale model by Dynamotive  http://quarterscalemerlin.com/. Unfortunately, the company have ceased making the castings and after making contact with the designer, there will be no more being made and he dose not have any more complete sets of castings.

I started to research in much greater depth and have found 2 builds on other forum's and both of these explained several concerns with the kits,

  • Warping of the castings
  • Cooling jacket dimensions to small (limiting run time)
  • Liner spacing
  • as well as several other minor design issues

This got me to thinking,can i design the same engine at quarter scale but correct many of the design issues? The simple answer is NO! I can correct the design issues but to make that happen, i will have to divert from the "quarter scale". In the big scheme of things, the model is not "true" quarter scale anyway as all of the nuts and bolts are not to scale as well as some of the other major design features. 1st question to you all is "dose it matter" not being true scale?  :shrug:

My plan is,


Design the complete engine in 3D CAD (i have already started this) and iron out the design flaws and then i will probably 3D print so as i can see any other issues. If all is good, i will move on to casting and then machining and assembly. I plan on creating a UTube series to document all the stages as well as help future builders.

On the commercial side, i do plan to sell kits to complete a build of the engine but i plan to offer several options,

  • Complete kit, all parts, machined ready to assemble
  • Complete set of casting (no other parts)
  • Complete kit of castings machined (no other parts)
  • instructions and technical drawing relevant to which kit you buy

I am nowhere ready to start pricing but i think i have come up with a way to spread the cost out. Using Patreon, subscribers pay a fixed amount each month over a 1 year period, once their subscription has started, their kit will be build and stored until the payment period is completed.

There are many many issues to iron out but i just wanted to get an idea of the interest within the UK first. I will almost certainly build the engine on my own but as i have said at the beginning, it would be nice to earn a little money as well as meet and make new friends.

Please post your thoughts and comments below.

Ian
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Offline b.lindsey

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Re: Merlin Engine
« Reply #1 on: July 21, 2019, 04:10:19 PM »
Ian, first of all welcome to the forum. You may want to add a bit more detail as to your modeling experiences and/or your shop in the introduce yourself section, where more may see it and add their welcomes also.

This is quite a challenging project though I am sure it will generate some interest. Please understand that this is not a "commercial" forum however, and although plans are offered at times, it is generally of completed, and tried and proven designs and is not the main focus of those members contributions to the forum.

Best wishes as you proceed with your research and build.

Bill

Offline Jo

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Re: Merlin Engine
« Reply #2 on: July 21, 2019, 04:15:02 PM »
Hi Ian,

A few things to think about:

1. How much is it going to cost? - Price will effect how many people will be interested & remember many who wanted one have already brought the original casting set (complete with its features)

2, Where are you going to get it cast? The prices UK foundry's charge have more than doubled in the last two years due to new health and safety requirements.

3, Have you made any model IC engines before?

Jo
Enjoyment is more important than achievement.

Online Vixen

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Re: Merlin Engine
« Reply #3 on: July 21, 2019, 05:23:11 PM »
Hello Ian,

Welcome to the MEM forum, It's a great place to hang out, to discus engine building with like-minder model engineers and perhaps also showcase your model engine builds.

I applaud your enthusiasm and ambition, a quarter scale Merlin has the potential to completely fill every available moment of your forthcoming retirement, especially if you intend to offer machined as well as raw casting kits to others. I expect it will require a considerable up-front investment in time and money before you have any hardware to put in the shop window. Only then, will others be able to see what's on offer, at what price.

Richard Maheux once said to me," Do you want to know how to make a little money from scale model castings?" I asked him what the secret was. He said " You need to invest lots of your money and most of your time". As you know, Richard went on to successfully sell a number of Merlin casting kits

Mike

« Last Edit: July 21, 2019, 09:49:24 PM by Vixen »
It is the journey that matters, not the destination

Offline Spark-Doctor

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Re: Merlin Engine
« Reply #4 on: July 21, 2019, 05:39:54 PM »
Ian, first of all welcome to the forum. You may want to add a bit more detail as to your modeling experiences and/or your shop in the introduce yourself section, where more may see it and add their welcomes also.

I will add my details in the introduction section later, sorry, did not see it  :-[

Quote
Please understand that this is not a "commercial" forum however, and although plans are offered at times, it is generally of completed, and tried and proven designs and is not the main focus of those members contributions to the forum.

Sorry if i gave the wrong impression on the commercial side. I have already bought several domain names and will have dedicated websites for the selling.

Ian

Offline Jo

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Re: Merlin Engine
« Reply #5 on: July 21, 2019, 05:50:30 PM »
We will be very interested in seeing your progress towards designing, making and seeing the first engine run  :)

While we are not a commercial site I have no problem with someone saying in their build thread I intend on making these commercially available please contact me via PM if you are interested. I often say the castings for this engine are available on this website and provide the link so prospective builders  know where they could get their own set of casting once in my build thread.

Jo
Enjoyment is more important than achievement.

Offline Spark-Doctor

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Re: Merlin Engine
« Reply #6 on: July 21, 2019, 05:56:51 PM »
1. How much is it going to cost? - Price will effect how many people will be interested & remember many who wanted one have already brought the original casting set (complete with its features)

I have only just started the CAD work so at this time, i have no idea of the cost. I have the ability to semi mass produce so setting up on a 6 axis machine is not much longer between 1 part or 30.

I have heard many figures on the amount that the original designer sold but can find very little info on people who completed them. I did find one man in France who got about half way but sadly died and his widow mistakenly thought the casting were scrap and threw them out.  :hammerbash:

Quote
2, Where are you going to get it cast? The prices UK foundry's charge have more than doubled in the last two years due to new health and safety requirements.

I have found a small foundry and pattern maker very close to me and after several discussions, have agreed that if i were to do the design work and 3D print some of the cores, the cost is greatly reduced. i have another meeting with them in 2 weeks to start discussing finer points and go over the drawings i have done.

Quote
3, Have you made any model IC engines before?

I work for one of the worlds largest engine manufactures producing prototype models. At the moment, i am working on modifications to a V20 diesel with Gen set attached.

Online crueby

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Re: Merlin Engine
« Reply #7 on: July 21, 2019, 06:37:22 PM »
Quite an interesting sounding project, looking forward to seeing the progress on it! The merlin is such an interesting engine, used in a variety of amazing craft.

Online Vixen

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Re: Merlin Engine
« Reply #8 on: July 21, 2019, 09:33:49 PM »
Hello Ian

I am sure you will be aware of the Terry Mayhugh build log for a 1/4 scale Merlin which appeared on the HMEM website.

For those of you who are not aware of this incredible feat of model engineering go to :

https://www.homemodelenginemachinist.com/threads/quarter-scale-merlin-v-12.24153/

Beware; it is a long and highly detailed build. It will give you all an insight as to what is involved.

Mike
It is the journey that matters, not the destination

Offline Spark-Doctor

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Re: Merlin Engine
« Reply #9 on: July 21, 2019, 09:37:20 PM »
I have shared a few emails with Terry, extremely helpful.  :NotWorthy: :praise2:

Offline Spark-Doctor

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Re: Merlin Engine
« Reply #10 on: July 21, 2019, 09:38:50 PM »
What i have been working on this evening. Bringing all the components into one drawing and getting the alignment spot on. I have the same image in animation but i cant upload even after i have compressed it.

You can view it here, https://drive.google.com/open?id=1ZMV0PPhfj7iCRHpdkGYWzz8TDsI5fFMy
« Last Edit: July 21, 2019, 10:22:36 PM by Spark-Doctor »

Offline Admiral_dk

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Re: Merlin Engine
« Reply #11 on: July 21, 2019, 10:47:54 PM »
Welcome.

There is one extremely well made Danish Merlin engine and he has big problem getting it to run ….

ALL the problems are ignition related  :zap:  :cussing:

I do personally believe that they are caused by him insisting on making the ignition system as an exact scale replica, but HIGH Voltage do NOT scale at all => almost all sparks are going to ground inside the distributer ….

Looking forward to follow your journey here  :ThumbsUp:

Best wishes

Per

Offline Art K

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Re: Merlin Engine
« Reply #12 on: July 22, 2019, 01:42:55 AM »
SD,
This sounds like a very ambitious project. I do recall a conversation with the gentleman who built a 1/6 scale Duesenburg J type, he never got it running with the scale distributor but did so when he used a larger one on the end of the cam, hid it under the cowling inside the car. Just food for thought.
Art
« Last Edit: July 22, 2019, 01:48:18 AM by Art K »
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