Westland Welkin RM16SM Merlin

[BarnOwlLover2]

Anyone have any info about this version of the Welkin? I know that one was built and was photographed in Jane's All the World's Aircraft 1947 edition. Of note is that it used chin radiators instead of the in-wing versions typical of the Welkin.

Also, I'm new here, and I posted this here since it was actually built (what was done with it I don't know). But if this fits better somewhere else, feel free to move it there.

 

[iverson]

Anyone have any info about this version of the Welkin? I know that one was built and was photographed in Jane's All the World's Aircraft 1947 edition. Of note is that it used chin radiators instead of the in-wing versions typical of the Welkin.

Also, I'm new here, and I posted this here since it was actually built (what was done with it I don't know). But if this fits better somewhere else, feel free to move it there.

It's usually fastest and most efficient to look for information yourself first. A bit of googling would be all you needed to find this information on Wikipedia:

Merlin 76/77 (RM 16SM)

1,250 hp (932 kW) at 3,000 rpm

1,655 hp (1,234 kW) at 3,000 rpm, +18 psi (124 kPa), 10,000 ft (3,048 m)

de Havilland Mosquito PR Mk.XVI, Mk.30, Welkin Mk.I

1,233 hp (919 kW) at 35,000 ft (10,668 m);[24] Fitted with a two-speed, two-stage supercharger and a Bendix Stromberg anti-g carburettor. Dedicated "high altitude" version used in the Westland Welkin high-altitude fighter, and some later Spitfire and de Havilland Mosquito variants.

The RM designations are, I believe, merely Rolls-Royce's designation for development engines.

The engine seems to have been broadly similar to the Merlin 73 that also powered the Welkin. Both were descendants of the 60-series Merlins. All had two-piece cylinder blocks and two-stage superchargers with air/water intercoolers between the supercharger outlet and the engine inlet manifolds.

The Welkin, like its predecessor the Whirlwind, did, in fact, have radiators in the wing leading edge, more or less like those on the Mosquito. I suspect that the prominent air inlet under the nacelle is for the intercooler radiator and/or the carburetor.

Information on carburetors can be found at https://www.calum-douglas.com/article-1-rolls-royce-merlin-carburettor-development/

 

[BarnOwlLover2]

Standard Welkins had a "normal" intake for the supercharger below the engine. It was designed for the Merlin 60 series engine from the start. The aircraft pictured has the Merlin RM.16SM engine, which was a member of the Merlin 100 family (similar to the Merlin 130s from the DH Hornet and the Packard V1650-9/11/23/25 Merlins from the P-51H and F-82B).

Doesn't explain the use of chin radiators vs the wing root type of the standard Welkin.

 

[iverson]

Standard Welkins had a "normal" intake for the supercharger below the engine. It was designed for the Merlin 60 series engine from the start. The aircraft pictured has the Merlin RM.16SM engine, which was a member of the Merlin 100 family (similar to the Merlin 130s from the DH Hornet and the Packard V1650-9/11/23/25 Merlins from the P-51H and F-82B).

Doesn't explain the use of chin radiators vs the wing root type of the standard Welkin.

Umm...where is it "pictured"? I do not see an image in your post.

I went from the information you supplied. The RM.16SM is not, to the best of my knowledge (which may be defective, I admit) a 100-series engine. It is 70-series and related closely to the 60-series engines. I have never seen a photo of a Welkin with a chin air intake.--just a drawing of DX340, an F.Mk.!. My best guess would be that the intake is not for an engine-coolant radiator, but for the aforementioned intercooler and carburetor intake.

 

[BarnOwlLover2]

Only pic I've found of it online, and it's not very good:

https://aviadejavu.ru/Images6/JS/Janes47/288-1.jpg

 

[red admiral]

Only pic I've found of it online, and it's not very good:

https://aviadejavu.ru/Images6/JS/Janes47/288-1.jpg

It looks like you can clearly see the port wing root radiator intake in that picture? Although the chin intakes are quite different.

From a bit more searching it looks like DX340 was modified for some trials. I imagine the intercooler or oil cooler radiator was relocated to the chin to provide more cooling area? The original chin intake for the carb looks really draggy but there definitely seems to be both more area and an exhaust so I'd be pretty sure a radiator is located in there too.