Aces High Bulletin Board

General Forums => Aircraft and Vehicles => Topic started by: MiloMorai on April 09, 2012, 11:16:35 AM

Title: R-R Merlin power
Post by: MiloMorai on April 09, 2012, 11:16:35 AM

Spitfire I

Maximum power the engine is designed to safely and reliability produce is ~400hp

This is the power produced at max continuous for 4 1/2 lb boost @ 2600rpm.

Thoughts and comments.

Title: Re: R-R Merlin power
Post by: Charge on April 09, 2012, 01:11:31 PM

Thoughts:

What is the definition of "safely and reliably"? Some certain amount of hours?

Is such low amount of HP the initial design aim of engine family from which Merlin emerged, i.e. not exactly what Merlin was capable of?

Where did you come by such figure?

-C+

Title: Re: R-R Merlin power
Post by: Klam on April 09, 2012, 02:23:28 PM

There is some useful stat's and info' pertaining to Merlin engine variants and the Spitfire

http://www.historyofwar.org/articles/weapons_spitfire_mkI.html

Title: Re: R-R Merlin power
Post by: MiloMorai on April 09, 2012, 05:32:51 PM

The person who made the statement said: "You are talking about running the engine at 3 times its original design maximum capacity."

Title: Re: R-R Merlin power
Post by: Jabberwock on April 09, 2012, 06:49:20 PM

Hmmmm, odd numbers. I'd estimate a Merlin III at + 4.5 lbs boost/2,600 rpm would be producing about 700-850 hp depending on altitude, not 400 hp. Merlin II maybe a touch less.

See: http://www.spitfireperformance.com/merlin3curve.jpg

Also, much depends on the time period. For example, when the Merlin III was cleared to operate at +12.5 lbs in 1940, the max continuous cruise was set at +7 lbs and 2650 rpm, which would give more than 1000 hp, depending on the altitude. 

See the first post here: http://forum.1cpublishing.eu/showthread.php?t=18865

Note the indicated values for the power curve at 13,500 ft, which gives 831 hp at 4.3 lbs boost.

Title: Re: R-R Merlin power
Post by: MiloMorai on April 09, 2012, 11:18:22 PM

Thanks Jabberwock, that is what I am looking for.

Title: Re: R-R Merlin power
Post by: NZTyphoon on April 10, 2012, 08:43:37 PM

Quote from: Jabberwock on April 09, 2012, 06:49:20 PM

Hmmmm, odd numbers. I'd estimate a Merlin III at + 4.5 lbs boost/2,600 rpm would be producing about 700-850 hp depending on altitude, not 400 hp. Merlin II maybe a touch less.

See: http://www.spitfireperformance.com/merlin3curve.jpg

Also, much depends on the time period. For example, when the Merlin III was cleared to operate at +12.5 lbs in 1940, the max continuous cruise was set at +7 lbs and 2650 rpm, which would give more than 1000 hp, depending on the altitude. 

See the first post here: http://forum.1cpublishing.eu/showthread.php?t=18865

Note the indicated values for the power curve at 13,500 ft, which gives 831 hp at 4.3 lbs boost.

Just to clarify; the Merlin II and IIIs were cleared for +12lbs boost in November 1939, while the Merlin XII in Spifire IIs was cleared for +12.5lbs at about the same time - check out http://www.spitfireperformance.com/spit1-12lbs.jpg  http://www.wwiiaircraftperformance.org/ap1590b.jpg the Merlin II's lowest power rating given in t=18865 = 684 hp at +2.2lbs