Merlins > Packard vs RR

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Hi Greg,


The V-1650-7 was supplied to the British as Merlin 266s. They differed from the Merlin 66 in the supercharger drive (epicyclic, designed by Wright) and the injection carburetor Vt

A minor point. The Merlin 66 did use the Bendix injection carb. Also Packard used a different intercooler which necessitated modifications to the Spitfire IX cowling. The following website tells more about Spitfire cowlings than you may want to know:
Spitfire Mk. IX, XI and XVI – Variants Much Varied — Variants & Technology | Reference | Spitfire Mk. IX | Spitfire Mk. XI | Spitfire Mk. XVI
 
All of the dambuster Lancasters were built as Mark IIIs or reengined with Merlin 28s. This was because the two piece block of the 28 allowed higher boost pressure for take off.
 

Was the intercooler different, or was it positioned differently due top the different supercharger drive?
 
All of the dambuster Lancasters were built as Mark IIIs or reengined with Merlin 28s. This was because the two piece block of the 28 allowed higher boost pressure for take off.
My point was they are essentially the same engine. The first "Mustang" was a two stage Merlin put in a Mustang MkI frame to replace the Allison engine. It was approx. 30 MPH faster than the same engined Spitfire. The P-51B/C and D were approximately the same difference 30 MPH while the Spitfire Mk IX and XVI were identical to all intents and purposes. The improbable power differences between the two which are often quoted would have caused rapid trips across the Atlantic if there was any truth, either massive mistakes had been made or new laws of thermodynamics discovered.
 
All of the dambuster Lancasters were built as Mark IIIs or reengined with Merlin 28s. This was because the two piece block of the 28 allowed higher boost pressure for take off.

And the Tallboy/Grand Slam carrying Lancasters were B.I (Special).

Rolls-Royce delayed changing to the 2 piece construction due to production requirements, so Packard got the 2 piece blocks first. But Rolls-Royce production did change to the 2 piece design soon after.
 
There was a long detailed post about this years ago that I just cant find, to do with all the rationalisation of production. The changes were planned by Rolls and agreed with Packard but since the engines were different they still had to produce a lot of other engines to avoid modifications to airframes already produced.
 
Was the intercooler different, or was it positioned differently due top the different supercharger drive?
The intercooler used by Packard had an integrated header tank while the one used by Rolls Royce had a separate header. The following website shows a Merlin 266 intercooler vs. Merlin 76. Note that it is a Merlin 76 which seems to have a combined intercooler/header. The Mosquito that had a different cooling system than other Merlin applications, which may explain this.

Rolls-Royce Merlins and Packard Merlins
 
 
Simply put in 1941 the Merlin was the only viable engine the British had in production. It was not possible to lose any production whatsoever. Since Packard was starting from scratch no production was lost.
It is simple to put it simply but things were anything but simple. The decision was made in 1940, but RR still had to produce Vulture and Peregrine engines while scaling the production down. The Merlin itself was not one engine, they had to improve the single stage engines, develop and put into production the two stage engines and then there were the Griffon series. Engines on Mosquitos had one side with the coolant flow reversed because of the wing mounted radiators.
 

I believe the Mosquito had the same engine model for both sides, at least until the 2 stage engines, especially those with cabin pressurisation.

The coolant flow was reversed from front-to-back to back-to-front (IIRC) because of the radiator position.
 
All very true. Also getting the 2 piece block into production. The original Packard version had external coolant piping between the head and block whereas the Rolls Royce version had internal connection. I have not found any information on why there was a difference.
 

Packard developed their own system.

But I believe they later adopted the Rolls-Royce system.
 
Pilot who doesn't know what he's flying I'd say, power could be anything between 1,280 and 1,640 HP depending in which version of Merlin installed.
 

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