Merlin/Griffon Question

Bill Greenwood · **Posted:** Mon Mar 03, 2008 1:30 pm

It is often alleged that the Spitfire prop turns the reverse of US planes. Of course, this is not true for the Merlin Spit or Hurri which turns clockwise as seen from the pilot view. The Griffon is opposite. Does anyone have any figures on how many Spits were built with Merlins vs Griffons? What were the production numbers?

famvburg · **Joined:** Fri Oct 07, 2005 9:41 am **Posts:** 540

Some of the Merlins turned opposite, didn't they? Of course the Griffons with c/r props had it both ways..........

Bill Greenwood wrote:

It is often alleged that the Spitfire prop turns the reverse of US planes. Of course, this is not true for the Merlin which in a Spit or Hurri turns clockwise as seen from the pilot view. The Griffin is opposite. Does anyone have any figures on how many Spits were built with Merlins vs Griffins?

Bluedharma · **Posted:** Mon Mar 03, 2008 3:41 pm

I didn't know of any Spits with Counter-rotating propellers.
I had only heard of the Griffons with the contra-rotating props.
But after looking around a bit I found this.

Quote:

that the contra-rotating griffin arrangement was developed for the carrier version of the Spitfire.
The torque reaction from single rotation Prop would turn the plane to the right.
If a pilot applied full throttle to go round again after abandoning a landing, he would find himself flying into the flight deck island,
so a contra-rotating prop was essential for naval flying.

http://www.airliners.net/discussions/tech_ops/read.main/101968/
I always thought it was about greater engine power, not a torque issue.
Is this true?

Old SAR pilot · **Posted:** Mon Mar 03, 2008 3:54 pm

Notes on the Griffon:

http://www.unlimitedexcitement.com/Grif ... escription

Once again, it's not torque (roll axis) that pulls to the left (or right) (yaw axis)...it's a thing called "P-factor", as per below (among many other sources):

http://en.wikipedia.org/wiki/P-factor

Bluedharma · **Posted:** Mon Mar 03, 2008 4:06 pm

Old SAR pilot wrote:

Notes on the Griffon:
Once again, it's not torque (roll axis) that pulls to the left (or right) (yaw axis)...it's a thing called "P-factor", as per below (among many other sources):

Old SAR pilot,
Thanks for clearing that up for me.
Was the change to c/r because of the P-factor on flight decks?

Best Regards,

K225 · **Posted:** Mon Mar 03, 2008 4:15 pm

It was my undertsanding that from the MkXII on Spits had the Griffon with the exception of the MXVI it had the Packard Merlin 266.
Any experts out there?

gregv · **Posted:** Mon Mar 03, 2008 4:25 pm

A handy breakdown of Spitfire/Seafire types with basic details here:

http://www.spitfiresociety.demon.co.uk/whatmark.htm

famvburg wrote:

Some of the Merlins turned opposite, didn't they? Of course the Griffons with c/r props had it both ways..........

I think it was just the Merlins as installed in the DH Hornet that had counter-rotating props; I wonder if this was handled in the reduction gearing or if it was the entire engine that rotated in reverse (like the Allisons in the P-38?)?

cheers

greg v.

Old SAR pilot · **Posted:** Mon Mar 03, 2008 4:25 pm

Bluedharma wrote:

Quote:

Was the change to c/r because of the P-factor on flight decks?

That, I couldn't say. However, in a quick search, it is noted in the following site that the Griffon was originally designed to run in a counter-clockwise fashion, but was changed in 1940:
http://www.spitfiresociety.demon.co.uk/engines.htm

Also, for Spit affecitionadoes, the following site (which you may have seen) has a bit on info on the various types:

http://www.battleofbritain.net/0011.html

RNDMTRS4EVR · **Posted:** Mon Mar 03, 2008 10:18 pm

I thought the one of the Merlins on the P-82 turned the wrong way, or am I the wrong way? :rolleyes:

dhfan · **Posted:** Tue Mar 04, 2008 2:30 am

gregv wrote:

I think it was just the Merlins as installed in the DH Hornet that had counter-rotating props; I wonder if this was handled in the reduction gearing or if it was the entire engine that rotated in reverse (like the Allisons in the P-38?)?

cheers

greg v.

It was in the reduction gear. RR made complete opposite hand engines for the Peregrine in the Westland Whirlwind and decided it was too much trouble.

JDK · **Posted:** Tue Mar 04, 2008 7:56 am

What was the question again? :rolleyes:

Old SAR pilot wrote:

Once again, it's not torque (roll axis) that pulls to the left (or right) (yaw axis)...it's a thing called "P-factor",

But a contraprop addresses that issue as well, surely?

Just for clarity (ha ha) in British English, as we are discussing a British design, it's usual to refer to 'handed' propellers on a twin engine aircraft with a single row prop turning (inwards or outwards) in opposing rotation. A 'contraprop' is a two row set of two propellers on a single engine rotating in opposite directions. 'Counter-rotating' isn't a common use (I think) in Commonwealth accounts.

The contraprop on the Griffon-powered Seafires I vaguely recall was to avoid the effects of torque (not correctly referred to as p-factor at the time, although I take Old SAR pilot's point) but also as a means to transmit the thrust through a reasonably sized prop disc - hence two sets of three blades.

Cheers

Bill Greenwood · **Posted:** Tue Mar 04, 2008 12:25 pm

Everybody is focusing on the variations. What I was hoping was somebody might have production numbers or at least a close estimate of how many Spitfires were built with Merlins and how many with Griffons? All the Merlin Spits turn the same way as US planes, thus the column in AOPA is mostly incorrect when it talks about turning the opposite.

Bluedharma · **Posted:** Tue Mar 04, 2008 12:42 pm

I guess I wasn't sure Bill. That was why I asked about the contraprop.

This site has approximate figures for Merlin Variants...
http://www.spitfireart.com/merlin_engines.html

Best Regards,

gunnyperdue · **Posted:** Tue Mar 04, 2008 1:48 pm

Bill Greenwood wrote:

Everybody is focusing on the variations. What I was hoping was somebody might have production numbers or at least a close estimate of how many Spitfires were built with Merlins and how many with Griffins? All the Merlin Spits turn the same way as US planes, thus the column in AOPA is mostly incorrect when it talks about turning the opposite.

Bill-

According to "The British Fighter" Francis Mason, there were 1,836 examples of the Mk XII thru Mk 24 Griffon powered Spitfires made.

BTW the P-82 was powered by 'two' different power plants... the XP-82/P-82B used Merlin V-1650-19/21 (1860 HP), the P-82E/F/G used Allison V-1710-143/145 (1600 HP).

gunny

Old SAR pilot · **Posted:** Tue Mar 04, 2008 3:48 pm

Bill,

The following site has numbers - scroll down onnit...

http://www.battleofbritain.net/0011.html

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