PPRuNe Forums

Go Back   PPRuNe Forums > Flight Deck Forums > Tech Log
Forgotten your Username/Password?

Tech Log The very best in practical technical discussion on the web


Reply
 
Thread Tools
Old 3rd May 2011, 23:53   #1 (permalink)
 
Join Date: Feb 2009
Location: Jungles of SW London
Age: 67
Posts: 338
Griffon vs Merlin rotation.

Just watched a Youtube vid on the Military forum, of the BBMF starting up and departing for the Royal wedding flypast.

Unless I am mistaken, the Merlins on the Hurricane and - the starboard engines certainly - the Lancaster rotate clockwise as seen from behind, while the Griffon in the PR Spitfire rotated ACW.

Two question arise, I suppose. Is that in fact the case and why? Followed by was the Merlin ever 'handed' for right and left side on multis?

I know the Griffon went back to the 'R' Type 36 Litres, so did it also inherit the 'R' Type rotation?

Roger.
Landroger is offline   Reply
Old 4th May 2011, 03:08   #2 (permalink)
 
Join Date: Mar 2011
Location: Canada
Age: 43
Posts: 43
From the Wikipedia page on the Griffon engine:
"Pilots who transitioned from the Merlin to the Griffon engine Spitfires soon discovered that, because the Griffon engine's propeller rotated in the opposite direction to that of the Merlin..."

I have that in another text too, which states that Griffon-engined spitfires handled very differently to the earlier marks, largely due to the opposite engine rotation.
photofly is offline   Reply
Old 4th May 2011, 03:13   #3 (permalink)

 
Join Date: Aug 2003
Location: Sale, Australia
Age: 70
Posts: 3,820
The Merlins on the Hornet were handed - ie rotated in opposite directions.

The direction of rotation on the Griffon was the result of the Society of British Constructors deciding in the late 1930s to standardise the direction of rotation.

The R engine rotated clockwise as seen from the cockpit.

Last edited by Brian Abraham; 4th May 2011 at 03:26.
Brian Abraham is offline   Reply
Old 4th May 2011, 03:29   #4 (permalink)
 
Join Date: Sep 2002
Location: Enzed
Posts: 1,420
Quote:
I have that in another text too, which states that Griffon-engined spitfires handled very differently to the earlier marks, largely due to the opposite engine rotation.
Certainly the rotation direction was a major difference, but from a basic handling point of view I think the comments probably related to the extra torque that had to be controlled by the same size tail feathers as the lower powered Merlins (at least until the very latest marks that had bigger tail surfaces) and the extra weight up front which affected the C of G.

It was generally recognised that the Griffon Spitty's were not as nice to fly as the Merlin ones. Though I have seen it written that the lastest marks (I think the Mark 24 and 47) were the nicest Griffon versions as they had the bigger tails.
27/09 is offline   Reply
Old 4th May 2011, 14:31   #5 (permalink)
 
Join Date: Jun 2002
Location: east ESSEX
Posts: 2,170
The Merlin was `handed` for the deH Hornet.
sycamore is offline   Reply
Old 4th May 2011, 14:39   #6 (permalink)
 
Join Date: Jun 2001
Location: Fragrant Harbour
Posts: 4,025
I heard an account of a delivery pilot collecting a MkXII Spitfire for the first time. She got a briefing off a company test pilot who mentioned everything about the new aircraft - except for the fact that the prop went the other way round. It made for a very excitng take off!
Dan Winterland is offline   Reply
Old 4th May 2011, 16:36   #7 (permalink)
 
Join Date: Sep 2007
Location: North Wiltshire, UK
Age: 68
Posts: 153
IIRC the Packard Merlins rotated the same way as the Griffon

I think this is why the Mk XVI had a different mark number to the otherwise identical Mk IX

(Old age and failing memory excepted )
diesel addict is offline   Reply
Old 4th May 2011, 18:47   #8 (permalink)
 
Join Date: Feb 2009
Location: Jungles of SW London
Age: 67
Posts: 338
Thanks guys.

I love this forum - not only do you usually get the answer to the most obscure questions, but a whole lot of incidental information.

I'm not a pilot and thus didn't think the issue through automatically, but I am an engineer and I should have realised at once. Rotating the donk the other way, especially one as powerful as the Griffon, would really make your eyes water in the wrong circumstances. It would fly very differently.

Thanks again guys.

Roger.
Landroger is offline   Reply
Old 4th May 2011, 23:33   #9 (permalink)

 
Join Date: Aug 2003
Location: Sale, Australia
Age: 70
Posts: 3,820
Quote:
IIRC the Packard Merlins rotated the same way as the Griffon
Sorry, not the case.
Brian Abraham is offline   Reply
Old 5th May 2011, 02:13   #10 (permalink)
 
Join Date: Sep 2002
Location: Enzed
Posts: 1,420
To illustrate the controlability issues of the Griffon engined Spitfires with the small tail surfaces.

From the Pilots Notes of the Mark XIV and XIX, Griffon 65 or 66 engines.

Para 49 (i)

"When ever possible open the throttle slowly up to +7lb/sq. in boost only. This is important as there is a strong tendency to swing to the right and to crab in the initial stages of the take off run. If much power is used tyre wear is severe. +12lb/sq. in boost may be used at heavy load and should in any case be used on becoming airborne to minimise the possibility of lead fouling of the sparking plugs, but +7lb/sq. in boost is suffficient for a normal take off"
27/09 is offline   Reply
Old 5th May 2011, 02:20   #11 (permalink)
 
Join Date: Jan 2008
Location: On the lake
Age: 72
Posts: 499
Quote:
Rotating the donk the other way, especially one as powerful as the Griffon, would really make your eyes water in the wrong circumstances. It would fly very differently.
50+ years ago, when I was a 17 year old sprog with a brand new PPL and 40 hours on the Fleet 80 'Canuck' (with clockwise rotation) a friend with access to a Chippy offered me a flight in it - which I accepted, of course - it was FREE.

Without much briefing he passed control to me as we lined up on the runway. As 'I' lifted off I got the impression he had taken control of it as the aircraft swung right, slightly nose down; I let him continue what he wanted to do - he was in command, wasn't he?

After going in between the hangars of Carp airport at 70' with nobody in real control, Steve said "Next time I fly it"!

We both learned about 27 lessons that lovely day and 'next time I fly it' wasn't one of them!
twochai is offline   Reply
Old 5th May 2011, 16:57   #12 (permalink)
 
Join Date: Sep 2007
Location: North Wiltshire, UK
Age: 68
Posts: 153
Brian Abraham -

Ooops !

Apologies for relying on memory -
I really do not know where that came from, one is fully aware of the L/H Merlin R/H Griffon ( excepting the Merlin 131 / 134 of course ) - brain fade, crossed wires .......
diesel addict is offline   Reply
Old 5th May 2011, 17:18   #13 (permalink)
 
Join Date: Feb 2008
Location: In the Old Folks' Home
Posts: 349
Reversible Engines

The Allison engines in the P-38 Lightning were identical but were installed facing different directions to get the props to rotate in opposite directions. This was simpler than building the engines differently by using different valve camshafts and simplified the supply problem. Does anyone know if the Merlins and Griffons were capable of being installed "backwards"?
Smilin_Ed is offline   Reply
Old 5th May 2011, 18:04   #14 (permalink)
 
Join Date: Sep 2007
Location: North Wiltshire, UK
Age: 68
Posts: 153
Smilin Ed -

The oipposite handed Merlins ( Mk 131 and 134 ) changed propellor rotation direction via an additional idler pinion in the reduction gearbox, the whole unit aft of the gearbox was unchanged - whether that is less simple than fitting the engine "backwards" is debatable ?
diesel addict is offline   Reply
Old 5th May 2011, 18:35   #15 (permalink)
 
Join Date: Feb 2005
Location: flyover country USA
Age: 72
Posts: 4,178
Smilin_Ed:
Quote:
The Allison engines in the P-38 Lightning were identical but were installed facing different directions to get the props to rotate in opposite directions.
Don't think so - it was the crankshaft that was reversible. (I had thought it was the camshafts that reversed, but was later advised differently)
barit1 is offline   Reply
Old 5th May 2011, 19:59   #16 (permalink)
 
Join Date: Feb 2005
Location: flyover country USA
Age: 72
Posts: 4,178
Another aspect to Allisons reversing rotation: I believe they were designed, among other things, for dirigible use; and they could be shut down and reverse-started in flight for docking operations.

Not sure just how this was done, although it might have included reversible bevel gears on tower shafts driving the cams.
barit1 is offline   Reply
Old 5th May 2011, 20:18   #17 (permalink)
 
Join Date: Dec 1999
Location: Not here any more.
Posts: 626
Cows are more valuable

Back in my earlier days when I had the chance to fly with many WWII vets there was a favourite captain I flew with who had lots of great stories, one of which how he used to fly Spitfires but made the mistake of volunteering for Asia duty after VE Day and was assigned Mustangs. Told me on his first Mustang take off in India he lost control of the aircraft and hit a house, killed a cow and was court-martialed, not for writing off the aircraft but for killing the cow.
NG_Kaptain is offline   Reply
Old 5th May 2011, 22:09   #18 (permalink)
 
Join Date: Feb 2001
Location: right here inside my head
Age: 55
Posts: 177
Gents.... Brits turn their motors backwards. The Yanks have them going the right way around....[] So, the "licence built" Merlins, built in the US of A, turn CW (from aft looking forward), and the Brit built Merlins and Griffons turn backwards, unless they to maintain the centre of thrust on multi's.
3holelover is offline   Reply
Old 5th May 2011, 22:38   #19 (permalink)
 
Join Date: Sep 2002
Location: Enzed
Posts: 1,420
Quote:
and the Brit built Merlins and Griffons turn backwards, unless they to maintain the centre of thrust on multi's.
Not so old chap.

The Packard Merlin variants turned the same way as the Britsh ones. It was the Griffon engine that turned the opposite direction.
27/09 is offline   Reply
Old 5th May 2011, 22:56   #20 (permalink)
 
Join Date: Feb 2001
Location: right here inside my head
Age: 55
Posts: 177
OK... izzatafact? I'll defer to your greater knowledge... Sorry mate, I shoulda said, I'm repeating what I've read, but it probably came from some Time/Life magazine or something... I'd kill to fly anything with a Griffon or a Merlin in it! [I've named two dogs after each] But I've never put myself airborne with anything beyond an O320...

I can well imagine the torque effect of a single 1500-2000 hp monster, swingin' a full paddle wheel of prop blades, would be quite the animal to tame... One would certainly like to know which foot to have ready...
3holelover is offline   Reply
Reply
 
 
 


Thread Tools


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT. The time now is 13:51.


vBulletin® v3.8.7, Copyright ©2000-2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
1996-2012 The Professional Pilots Rumour Network