Spitfire F Mk IX (1942 - Channel)

Sorry to hear about the HD - that sucks Sad

But good to hear that you'll be back up and running soon Smile

Keep us posted M8.

~S~ Redcanuck
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Well I thought that I had found the motherload of spitfire info at
http://www.nationalarchives.gov.uk/catal...MARKERSCN=
(UK national archives)

But........I was quoted https://www.nationalarchives.gov.uk/reco..._id=347366
449.60 pounds
for a downloaded copy of one of those documents :o Confusedhock: :? :lol:

Needless to say I cant afford that :lol:
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[quote="GBrutus"]
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You can view the documents in person - I don't think that it would be very costly.

But....... I live several thousand kms away lol.

You wouldn't even know if it was useful info until you downloaded it :roll:
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GBrutus - Hows the HD issue?

Any updates on the model?
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New drive has arrived and I'm just about up and running again. Need to finish installing all my essential stuff then I'll be back in business. I'll post an update as soon as I'm able which hopefully wont be too far away. Sorry for the hold up, I'm keen to get this rolling too.
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Idea

Edit: Big Grin
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GBrutus Wrote:New drive has arrived and I'm just about up and running again. Need to finish installing all my essential stuff then I'll be back in business. I'll post an update as soon as I'm able which hopefully wont be too far away. Sorry for the hold up, I'm keen to get this rolling too.

Big GrinBig GrinBig GrinBig Grin
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The Merlin 61 really is very tricky. There is absolutly no real data. Only guesses. There is an article in the 1C maddox forum about the captured 190 and tests between this plane and the spit Vb and Spit IX

We can
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I/JG27_Waggel Wrote:Little Off topic
I like to make historical correct planes. There was no early Spit IX with 4 cannons. Even if there was one single Spit IX with four cannnons you will not like to fly her. The 4c flew like an old bag. Fighter pilots did not like her because she had 0!!! agilitiy. This plane only as usefull to intercept bombers. In a dogfight this plane simply was outclassed.

Theirs a flight test on spitperformance site of the mkVc with 4 cannons vs the 2 cannon armed one and they found little difference in handling, theres not a great deal of weight difference as they are just replacing the 2 303mgs with a cannon. The reason i heard for their not being many 4 cannon spits was issues with the gun heaters.
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I/JG27_Waggel, you can't use in game Vb speeds as a basis for calculating the new F IX's speeds are they're not correct.

Both the Spitfire Vb and Hurricane I & II were placed in the game to represent aircraft flying with the Russians (or Finland for Hurricane I) on the early Eastern Front. These aircraft due to lower quality fuel used lower boost ratings for their engines and hence had lower speeds than their western front counterparts.

[quote]When Rolls Royce designed the Merlin engine, it deliberately went against the world trend and used a carburetor instead of fuel injection. While fuel injection provides and easy and precise method of providing the correct amount of fuel for powerful engines it looses the charge cooling effect of a carburetor which added up to 300hp to Merlin engines. Rolls Royce believed that by careful engineering it could work out all the carburetors disadvantages while retaining all of its advantages. With the SU carburetors of 1943, they largely achieved this.

Unlike a WW2 supercharger where the fuel is squirted directly into the hot and turbulent eye of the supercharger impellor, the fuel in a carburetor is vaporized in the passing air flow. For this to occur successfully at high altitudes or high boosts, it is extremely important that a high volatility fuel is used. For the English, the world leaders in aviation fuels, this wasn
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Now that's the kind of posting I love. Simple to understand, illustrative and very authoritive.

I'm always confused by the old imperial versus continental metric boost ratings. I like mm of mercury, a far better system than trying to convert one to the other.

According to the above quote the Merlin achieved a manifold pressure of up to 2070mm of mercury.
Whilst the DB-605DC achieves up to 1504mm of mercury.
Soviet planes seem to get up to around 1150mm of mercury iirc.

However I am unsure as to how accurate the British "+25lbs" system of measuring is, according to engineers much less so than inches or millimetres of mercury. This rating is to say, that the equivalent of 40PSI total pressure is being forced into the engine. A top fueller sucking alcohol doesn't get that much. It's ridiculously high octane rating isn't enough to prevent the heads blowing right off. Its titanium pistons and one piece shotpeened billet steel crankshaft would desintegrate even if this didn't happen. It gets around 3000hp from 8 litres with about 28PSI and all that expensive hardware is just to cope with this much.

I'm not one to doubt the experts. I just...wonder.

Then there is the consideration of the regional manner in measuring fuel ratings. According again to engineering sources the German fuels were measured differently and very conservatively compared to the American/British system of rating octane. I've been instructed the 87 grade B4 fuel is approximately equivalent to US 130 grade Avgas, whilst 96 octane C2/3 is roughly equivalent to 150 grade. Certainly other factors are involved in fuel quality. But I should mention volatility is what octane describes, it actually goes down as octane goes up, that's how it stops pinging, that's what octane rating means. But different fuel qualities regardless of octane atomize differently and burn differently, so I should let that one pass since I think it is what the author meant by "volatility."

Again, an argument is not what I'm looking for at all. I noted this in passing (researching other stuff) so if I hunt down a link for you I'll let you know. I don't really care so much, but neither do I about challenging popular (mis)conception.

The higher output/capacity relationship of the Merlin engine was achieved by running at higher operating speeds than the Daimler, not amazing boost and fantastic fuel types...from a race engineering point of view leastways. But sure, from my armchair it was magical liquids and more boost than Kitt the Knightrider car :wink:

I could run a model using Engine Analyzer Pro (race engineering software) but I already know what it'll turn out. Horsepower is a product of fuel combustion, period. Superchargers must be sized for volumetric capacity. To get around 2000hp out of 27 litres @ 3000rpm I imagine you need something like 15 psi total supercharger pressure, and an appropriately sized casing (cfm rating).

But who am I to argue, a mere human.
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Quote:I'm always confused by the old imperial versus continental metric boost ratings. I like mm of mercury, a far better system than trying to convert one to the other.

How to convert boost..
The German measured their boost in atmospheres from a vacuum. A DB605 without MW50 was limited to 1.42 Atmospheres (ATA) or .42 atmospheres above normal air pressure. Any reading below 1 ATA means fuel is being sucked in by vacuum from the cylinders and not forced in by the supercharger. The absolute minimum is zero.

The English measured boost in pounds per square inch above 1 atmosphere. There is 15 PSI to an atmosphere. Because readings are taken from 1 Atmosphere, you can have negative readings on an English blower gauge i.e. -7.5 PSI indicates that the boost is half an atmosphere (7.5/15) and fuel is being sucked in by vacuum from the cylinders and not forced in by the supercharger. The absolute minimum is -15PSI
So a Merlin 60 series running on 150 grade was capable of 25 PSI which mean 40 PSI from vacuum (25 + 15) and equates to 2.67 ATA (40/15)

The Americans measured their boost in inches of mercury from vacuum. There
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Thanks for the info totalspoon, I sure have been learning a lot with this thread.

@ Waggel:

I've been giving your last post a lot of thought.
I know that when the spit mk IXs first appeared the spit pilots were thrilled, and achieved almost immediate successes against Fw 190s.

This doesn't fit with what you were saying:

[quote]I made this guesswork with all the data I got and the Spit IX is very slow compared to the 190 in low regions. But in middle altitude the have the same speed ad in high altitudes the Spit IX is much faster. It really goes this way, that the spit IX was no answer to the 190 but to the "H
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