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ATAG_Snapper
May-04-2012, 17:10
Here's some interesting data I gathered today flying the Spifire Mark Ia and IIa from Cliffs of Dover and Air-2-Air (A2A) Simulations Wings of Power 3 Spitfire. Just a quick test comparing the following:The two sims' Spitfire Ia and IIaA2A's 100 octane vs 87 octanePerformance (Airspeed Indicated -- AIS) at 0 feet, 5,000 feet, and 10,000 feet.Two boost settings: 2.5 lbs and Full OverboostTwo rpm settings: 2800 rpms and 3000 rpmsThe methodology was pretty basic. Full gas tank and ammo load, take off from coastal airfield, fly to given altitude, close radiator halfway, adjust engine settings (prop pitch -- rpms, throttle -- boost), then trim for level flight at the designated altitude and note airspeed indicated (AIS) after a minute or two once the speed remained constant.Quite an eye-opener. I'll have to convert the 5,000 and 10,000 AIS data to True Air Speed (TAS). One note: CoD Spits do NOT like 2800 rpms as indicated by engine/airframe vibration. I actually blew the IIa Merlin at 3,000 rpms at 10,000 feet.Fuel Mixture was left at Auto Rich in both aircraft for all trials.NOTE: This is not a definitive test by any stretch of the imagination, this is why I've just posted this to the ATAG Forum. Conclusion: the CoD IIa more closely matches the A2A's Ia and IIa performance; the CoD Spitfire Ia just sucks dust -- no surprise there. :bgsmile:Interestingly, the A2A Spitfire Ia does NOT have a Constant Speed Prop, although the C0D Spit Ia does. The A2A Spit Ia has a 2-speed prop, but it's one step more authentic than the CoD's Spitfire Mark I 2-speed prop.....you can change pitch manually between Coarse and Fine. The real BoB pilots quickly discovered that if you carefully move the 2-speed prop pitch control (which looks like a bicycle pump handle, it's not a lever at all!!) in between the two extreme pitch settings, you can actually get intermediate pitch settings on the propellor. This was major in extracting optimum power from the engine. However, because it wasn't a Constant Speed Prop, they had to keep an eye on it at all times because the rpms would go up and down depending on boost level, and even when you changed direction or altitude. Like all good pilots, they got really good at judging the prop pitch/engine rpms by ear, so they didn't have to keep staring at their tachometer all the time. (It's like a Harley Davidson with a tachometer.....clearly its frickin' exhaust pipes aren't LOUD ENOUGH!!!! LOL)In my haste to get this out to everyone here, I haven't even looked over the data to analyze it yet -- I just double checked it for no typos. Laugh, weep, or throw bottles -- knock yerselves out! :runaway::hiding:EDIT: I'll do this again post patch. I didn't do the 18,000 feet altitude trials due to time constraints, plus I admit it does stick in my craw. ALL of my dogfights against 109's have been at 10,000 feet or less -- usually MUCH less. Even when jumped by high-flying 109's as I'm engaging enemy bombers at 12K - 14.5K, the ensuing fight will occur at lower altitude because the Ia ain't much of a climber vs a 109.

Dutch
May-04-2012, 19:35
That's great info Snapper.

With regard to MkI, MkIa etc, even us 'old timers' seem to be getting sucked in with the CoD terminology, because of course the 'a' suffix was only necessary in retrospect when the cannon armed 'b' wing came out. The 'a' refers to the 8xBrowning wing, 'b' to cannon+mg wing etc.

In that sense, even the original 2 bladed wooden fixed-pitch prop Spits MkIs were 'Ias'. That's how I understand it, anyway.

I can't remember now what the difference was in the game's MkI and Ia before they gave us the CSP in the Ia. They both had 2 speed props before the last patch. Maybe a bit of a performance difference with weight vs power? Dunno.

ATAG_Snapper
May-04-2012, 19:54
Re Mark I vs Mark Ia, etc: Yeah, I'll have to read up on ol' Alfie Price myself (I have two copies - one I bought, the other was under the Christmas tree! :happy).

This test pilot stuff is hard work: mostly from repeatedly crawling under my desk to pick up the pencil that rolled under my rudder pedals. :bgsmile:

There are small differences between the CoD and A2A Spit cockpits -- namely the boost gauges. They all are scaled a little differently from each other (done deliberately to throw me off), plus none of 'em actually go to 12 lbs boost -- they just go off-scale at full overboost cut-off over-ride over-barrel over Dover. (These kind of jokes kinda miss the mark over at the banana forum. A serious lack of humour over there, what?).

It'll be interesting to see how the patched Spits stack up to this.

Dutch
May-04-2012, 20:01
Here's a nice concise guide to wing types I just found;

http://spitfiresite.com/2010/04/concise-guide-to-spitfire-wing-types.html

Interestingly, Douglas Bader insisted on flying a MkVa in preference to a cannon armed Vb right up to when he was captured.

But then he always was a bit of a strange geezer. :Grin:

ATAG_Snapper
May-06-2012, 07:58
That's a great link on the wing types, Dutch, very clear and concise. Thank you!

Douglas Bader was certainly a man of strong convictions and didn't always follow the crowd, so I gather. LOL (putting it mildly, eh?)

I wonder if he preferred the guns over cannon because deflection shooting was a bit easier with guns (higher muzzle velocity)? Or perhaps guns had longer shooting duration over cannon? I'm sure the reason is in his memoirs somewhere!

(I remember reading that both Bader and Galland were handfuls to deal with during production of The Battle of Britain. Prima donnas!)

ATAG_Snapper
May-06-2012, 13:39
Just added beta performance data. Note the difference offline vs online for the Spitfire IIa!!!!