RR Merlin Scale Models

Hi all you dedicated model engineers.

Some years ago (40+) I went to a model engineers exhibition at (if i remember) Olympia.

A guy had produced a scale model of the Merlin. Not sure what scale, but must have been 1/4 or 1/2.

There where only 3 things that were not to scale:

1: the cylinder head bolt size/pitch were not to scale. Otherwise, if the engine run it would'he torn them out.

2:the magnets in either the starter motor or the magnetos had to be of a higher intensity to work (can't scale magnetism)

3: the 2 stage supercharger wouldn't work as you can't scale down the atmosphere

From my memory he started by building a model of the variable pitch propeller and didn't stop there, onto the engine.

I believe his ultimate goal was to build a scale model of the entire aircraft and fly it.

Does anybody know where this engine is now, did it happen?

Best regards Martyn

This is genuine request after 42 yrs with Ford Motor Company in research and development. I love engineering in any forms.

I saw it running at the show. I believe the engine was built by Barrington Hares and it was run by Prof Dennis Chaddock towards the end of one afternoon, after clearing a substantial part of the hall of people in the path of a possible runaway... In the days when such things were allowed - or at least, quietly ignored! Although "quiet" was not a relevant word in this context.

Impressive.

Ah! You were lucky!! I was there too but only heard it run such was the crowd. Where it is now Martin I have no idea and I don't think, though may be wrong, that it was destined for an aircraft. Barry Hares went on to do similar with a RR Eagle if I recall correct. There were some photos published at some stage of the stunning workmanship of this project but where I'm not sure - the now defunct Model Engine News perhaps?

Ramon

It was 1/5th scale, mention on MEN

There are a few of the casting kits about for the 1/4 scale one mentioned but there were problems with distorted castings so not much has happened since.

I saw the engine run at a lecture given to the Bristol branch of the Rolls-Royce Heritage Trust during the 1980s. I think he was asked about fitting it to a flying model and the reply was that it was far too powerful.

I don't know if the talk was written up in the Trust's magazine but it was probably filmed (this has been done for all the Bristol RRHT talks). In normal times the talk could be viewed but we have not had access to the archives since the middle of March.

JA

I did have the link to a better video of it running, but can't find it at the moment, so this will have to do for now:-

Edited By Nick Hughes on 19/11/2020 09:29:37

I seem to recall that Tony Walshaw (Son of Tom, Tubal Cain) also built one about his size.

I think there have been articles in ME about the Model Merlin.

It is possible to build and fly model aircraft in the quarter scale size and even bigger. This will vary between countries, and there are usually special requirements for models over a certain weight. It is unlikely that the Merlin would be too powerful when you consider that people are flying scale model gas turbines. Too much power is generally less of a problem than too little. WWII warbirds can be a bit tricky, they love to tip stall if you are a bit premature in trying to get them off the ground. Not ideal for a learner, but fine in the hands of an experienced flier.

A model of a WW1 rotary engine has been built and flown in a scale model. That was written up in RCME (sister publication to ME and MEW) a few years back IIRC. I think the model was of a Bristol fighter. Torque reaction effects could make that interesting, but apparently it flew well without problems.

John

No, this is not the engine I remember.

Which one? Two have been mentioned and looking back through the magazine indexes does seem to show two Merlin engines mentioned that would have been exhibited 40yrs ago.

A question I've often wondered about myself - where do these things go? Probably into the store in a museum somewhere , never to see the light of day again. The wonderful treasures there must be in museum stores. It ought to be mandatory that museums have to display everything that is given to them. People should stipulate that it any gifts. I went to the British Museum a few years ago hoping to see the wonderful collection of Japanese swords and carved ivory balls they have which I remembered from 40 years ago. Nothing! I asked about them and was told they would be in store.

Most of the Science Museum items, including models, are stored at Wroughton near Swindon. 30 or so years ago they used to have open weekend during the summer and at other times groups could have private visits. For well over ten years it has been firmly closed to the public. The curators decide what the public need/want to see and that is that. Their archives, also at Wroughton, can be visited by appointment.

Some of Cherry Hill's models have been given to the IMechE who have a far more open policy on this matter.

JA

I like the idea of smoking a pipe while fuelling up

I feel I should apologise to the Science Museum for my daily rant.

I have just looked at

**LINK**

and they are building a vast exhibition hall at Wroughton that should open in 2023.

A little good news.

JA

There are a few excellent model aero engines on display at the Shuttleworth collection. I can't recall much detail from my visit several years ago and I don't remember a Merlin but they are mostly, if not all, built by Les Chenery and include rotary types. I believe that they are all "runners.

It is a question I often ask myself, where do all these models of locos, ic engines and stationary steam engines etc end up?

Another question what proportion never get completed?

It would take me several lifetimes to build a model Merlin engine....that actually runs.

Happy xmas to all

Derek

The Bristol Fighter was powered by a Vee form liquid cooled Rolls Royce engine (Falcon as I recall ), a forerunner of the Merlin.

(There is an example in the Rolls Royce Heritage collection at the Sinfin site in Derby )

The "Brisfit" was distinguishable by the gap between the fuselage and the lower wing.

Air cooled Rotary engines (such as the Gnome, Le Rhone, Clerget, Bentley BR2 and their German counterparts ), were used in aircraft like the Vickers Gun Bus, De Havilland DH2, (Both "pushers" ) various Sopwiths, and the Avro 504, as well, of course, in the various Fokkers.

The Gnome Monosoupape (="Singlevalve" ) was unusual in that the the Inlet valve was within the Piston, so the only external valve needing to be operated was the Exhaust.

Initially, the advantage was the better power to weight ratio compared to the in line engines of the time, but development saw that overtaken.

Being lubricated by Castor oil, on a total loss system, the pilots emerged dirty after a flight, and never suffered from constipation!

Having no throttle, power was reduced for landing by using the "blip switch" which shorted out the magneto for as long as it was held down, so that the engine "windmilled" rather than producing power.

The son of the British Airports chief, (Masefield ) used to have a replica Vickers Gun Bus at Shoreham by Sea airport. On a Sunday morning it could be seen and heard, particularly during landing.

Because of the torque reaction the aircraft would roll more quickly in one direction than the other, which was valued by the fighter pilots of the time.

Howard

Earlier this morning I posted a link to the Science Museum Group web site. This not the Science Museum's web site.

It is well worth having a look at it. They have been quietly digitising their collection and putting it on line. There are good photographs of model and actual road vehicles, ships boilers and engines, railway engines, photographic collections and everything else. So far I have only looked at a few pages of what is obviously a vast number of pages.

Something else to do over Christmas.

JA

One evening I was viewing at a local auction centre, best known for house clearence, where the boxes of books were under the tables of goods ! I spotted a book with a pair of RAF type wings on it and the name GNOME. For £3 I bought the box, I had the workshop manual for the WW1 Gnome rotary Monosoupape Howard has mentioned. One statement was that the crankcase was filled with a non inflamable mixture, - but it's an internal combustion engine ? Petrol was poured into the hollow crankshaft which was also the air intake ! At this point the mixture was so rich it could not burn - only after the exhaust valve had stayed open long after TDC and partially filled the cylinder with fresh air that then mixed with the over rich mixture would it burn/ fire. The gyroscopic effect of the rotating cylinders did nothing for the handling or aerobatic characteristics of the aircraft. Another book in the box was, put simply, there's the aircraft, read the book, and then go fly ! Noel