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Author Topic: Spitfire dweebs - The Griffon (a question)  (Read 691 times)

Offline milian

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Spitfire dweebs - The Griffon (a question)
« on: October 16, 2005, 08:04:15 PM »
The GIII in the Mk XII had a maximum boost of +12.  The G65 in the Mk XIV had a maximum boost of either +18, +21, or +25.  The question is, does anyone know at what boost was maximum continuous cruise for each of these engines?  and what was the boost setting (and rpm) for climb power (30 or 60 minute).  And, does anyone have the horsepower (at SL) for these boost/rpm settings.  Iirc, the throttle controlled both the rpm and the boost.

And what happened to Ring's PRO documents website?
http://prodocs.netfirms.com/ and http://www.lanpartyworld.com/ww2/ are both down.
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Offline Kurfürst

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Spitfire dweebs - The Griffon (a question)
« Reply #1 on: October 17, 2005, 06:09:54 AM »
It should be found in the XIV manual, I can send it over if you give me an adress. BTW, +25 lbs was appearantly never cleared for the Griffon 65, I think it's the pet-idea of Mike Williams alone. All references through 1945 show the same limit, +21 lbs with 150 grade fuel, but it's not entirely clear how much use this has seen outside from a few months of V-1 chasing by 2-3 XIV squadrons in mid-1944.

The top cruise speed of the XIV was 380 mph iirc.
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Offline Guppy35

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Re: Spitfire dweebs - The Griffon (a question)
« Reply #2 on: October 17, 2005, 10:33:38 AM »
Quote
Originally posted by milian
The GIII in the Mk XII had a maximum boost of +12.  The G65 in the Mk XIV had a maximum boost of either +18, +21, or +25.  The question is, does anyone know at what boost was maximum continuous cruise for each of these engines?  and what was the boost setting (and rpm) for climb power (30 or 60 minute).  And, does anyone have the horsepower (at SL) for these boost/rpm settings.  Iirc, the throttle controlled both the rpm and the boost.

And what happened to Ring's PRO documents website?
http://prodocs.netfirms.com/ and http://www.lanpartyworld.com/ww2/ are both down.


Spit XII  (my particular favorite)

From the pilot's notes:

Max Take off to 1000 feet.  2750 RPM  +12 boost

Max Climbing One Hour limit  2600 RPM  +9 boost

Max Rich Continuous   2400 RPM  +7 boost

Max Weak Continuous 2400 RPM +6 boost

Combat 5 minutes limit  2750 RPM  +12 boost
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Offline Angus

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Spitfire dweebs - The Griffon (a question)
« Reply #3 on: October 17, 2005, 10:37:54 AM »
Hehe you'll never use the 1 hr limit on climb.
Anyway would you happen to have performance specs on that one?
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Offline Kurfürst

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Spitfire dweebs - The Griffon (a question)
« Reply #4 on: October 17, 2005, 12:28:48 PM »
Quote
Originally posted by Angus
Hehe you'll never use the 1 hr limit on climb.
Anyway would you happen to have performance specs on that one?


Why not ? You are not in a hurry (does 2-3 mins really make a difference on the usual, uneventful CAP mission for the day?), and it prolongs engine life...

WEP was far less used in practice than in flight sims, it was truely for 'emergency'.
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Offline Treize69

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Spitfire dweebs - The Griffon (a question)
« Reply #5 on: October 17, 2005, 12:41:01 PM »
Quote
Originally posted by Kurfürst

WEP was far less used in practice than in flight sims, it was truely for 'emergency'.


Amen. That why I love the way the "sim that shall remain unnamed" models overheating. You have to actually manage your engine wear, can't just fly around with the throttle firewalled all day.
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Offline Karnak

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Spitfire dweebs - The Griffon (a question)
« Reply #6 on: October 17, 2005, 01:17:40 PM »
Kurfurst,

I think he was saying that no WWII fighter could climb for one hour.  It would reach it's operational ceiling before it came close to spending an hour at climb power.

Quote
Originally posted by Treize69
Amen. That why I love the way the "sim that shall remain unnamed" models overheating. You have to actually manage your engine wear, can't just fly around with the throttle firewalled all day.

Problem is that their system is just a gamey kludge used as a gameplay mechanism with no bearing on historical engine behavior.  It is a difficult thing to balance the realistic behavior of engines with the fact that as game players we have no real reason to not abuse them.  Realism vs gamey forced historical use.

AH also uses a gamey forced limit on WEP.
« Last Edit: October 17, 2005, 01:20:16 PM by Karnak »
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Offline Kev367th

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Spitfire dweebs - The Griffon (a question)
« Reply #7 on: October 17, 2005, 08:58:40 PM »
Seem to remember from another thread, a short story about a Spit pilot who ran 'wep' for considerably (recommended) longer than 5 mins to escape.
Up around 30 mins?
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Offline MiloMorai

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Spitfire dweebs - The Griffon (a question)
« Reply #8 on: October 17, 2005, 09:12:35 PM »
5 minutes was only a recommendation. As long as the coolant and oil temperatures did not reach their limits, WEP could be used until the temp limit(s) were reached.
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Offline Angus

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Spitfire dweebs - The Griffon (a question)
« Reply #9 on: October 18, 2005, 10:37:04 AM »
I was referring to the climb to ceiling, - never spend an hour on that.
As well as fuel for WEP, - you'd leave little if any for normal settings.

As for the issue Kev mentioned it's right. I have this in some book. It was a Merlin engine though. Wepped through 30 minutes without any damage.
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It was very interesting to carry out the flight trials at Rechlin with the Spitfire and the Hurricane. Both types are very simple to fly compared to our aircraft, and childishly easy to take-off and land. (Werner Mölders)

Offline milian

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Spitfire dweebs - The Griffon (a question)
« Reply #10 on: October 21, 2005, 01:57:58 AM »
thanks for the info, another question . . .

Does anyone know what the "Gem" mods are, apparently it was an engine modification carried out by De Havilland.  Is this the +25lb conversion?
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