DCS Spitfire Mk IX performance

[Solty]

Actually it appears that the Spitfire will beat even the 109 climb.

 

Spitfire IX +18lbs 4200 ft/min

 

109 with MW50 3563 ft/min

 

https://www.digitalcombatsimulator.com/en/products/planes/kurfurst/

 

P-51 ~3200 ft/min

 

D-9 ~3300 ft/min

Sustained climb rate doesn't mean the aircraft is going to be good in a zoom climb. Sure, if both 190 and Spit get slow, the Spit can follow easily in vertical. But if they are entering a dive and reach 700kph the 190 will get ahead, gets some separation and zoom climb, he will be impossible to catch.

Edited November 10, 2016 by Solty

[MaxDamage]

And the fact that i wasnt mentioning sustained climb anywhere, but instead mentioned altitude in meters (advantage in altitude).

 

Spitfire IX can speed t ~510 kmh realistically at SL.

K4 and D9 can speed to ~590-600 kmh at SL.

 

And then the german planes start a vertical spiral the spitfire will never be able to follow because he will fall down 200-300 m earlier. This indicates a total domination in a vertical fight. You can do it very easily in War Thunder. For this reason none of the 1000 spitfires imported into the USSR saw any action it was too slow.

 

Spitfire can be tricky to shoot down though, it turns tight.

Edited November 10, 2016 by MaxDamage

[Krupi]

Sustained climb rate doesn't mean the aircraft is going to be good in a zoom climb. Sure, if both 190 and Spit get slow, the Spit can follow easily in vertical. But if they are entering a dive and reach 700kph the 190 will get ahead, gets some separation and zoom climb, he will be impossible to catch.

 

Not necessarily, that depends on the scenarios.

 

And the fact that i wasnt mentioning sustained climb anywhere, but instead mentioned altitude in meters (advantage in altitude).

 

Spitfire IX can speed t ~510 kmh realistically at SL.

K4 and D9 can speed to ~590-600 kmh at SL.

 

And then the german planes start a vertical spiral the spitfire will never be able to follow because he will fall down 200-300 m earlier. This indicates a total domination in a vertical fight. You can do it very easily in War Thunder. For this reason none of the 1000 spitfires imported into the USSR saw any action it was too slow.

 

Spitfire can be tricky to shoot down though, it turns tight.

 

War Thunder is not a particularly realistic sim lets be perfectly honest.

 

The real reason why the spitfire wasn't used much by the USSR was because the fighting was around 6000m and below and IIRC the majority of the spits they received were the Mk V which was by the time they arrived outclassed by the German aircraft.

 

This is why aircraft like the Mig 3 did not succeed it was a good high altitude fighter not low.

Edited November 10, 2016 by Krupi

[MaxDamage]

Not necessarily, that depends on the scenarios.

 

 

 

War Thunder is not a particularly realistic sim lets be perfectly honest.

 

The real reason why the spitfire wasn't used much by the USSR was because the fighting was around 6000m and below and the majority of the spits they received were the Mk V which was by the time they arrived outclassed by the German aircraft.

 

This is why aircraft like the Mig 3 did not succeed it was a good high altitude fighter not low.

 

Realistic or not we will never know. Both are pc programs for a home computer hehe. While probably less sophisticated in handling detail, war thunder will give very accurate kinetic performance relevant for speed and altitude evolution during combat etc.

 

~1100 spitfire IX were imported, not spitfire V. Problem is they were ~100 kmh slower then something like a la7 or d9 or k4.

[Krupi]

Realistic or not we will never know. Both are pc programs for a home computer hehe. While probably less sophisticated in handling detail, war thunder will give very accurate kinetic performance relevant for speed and altitude evolution during combat etc.

 

~1100 spitfire IX were imported, not spitfire V. Problem is they were ~100 kmh slower then something like a la7 or d9 or k4.

 

Agreed, however DCS and Il2 are known to be "more" realistic.

 

Hang on, what makes you think that about the kinetic performance?

 

V were imported before the IX & hopelessly outclassed by the time the arrived in 1943.

Edited November 10, 2016 by Krupi

[Solty]

Not necessarily, that depends on the scenarios.

 

 

 

War Thunder is not a particularly realistic sim lets be perfectly honest.

 

The real reason why the spitfire wasn't used much by the USSR was because the fighting was around 6000m and below and IIRC the majority of the spits they received were the Mk V which was by the time they arrived outclassed by the German aircraft.

 

This is why aircraft like the Mig 3 did not succeed it was a good high altitude fighter not low.

 

Through the war on the eastern front, most of the fighting happened at alt below 3000m.

[horseback]

Better sustained climb generally translates into better acceleration. Getting faster sooner is more important in a low-level furball than top speed, which means that the same guys who loooove their 109K because they can easily win in a dogfight where the other guy fights their fight (instead of forcing the fight on their own best terms) may well be thinking about switching to the Spit.

 

cheers

 

horseback

[Krupi]

Through the war on the eastern front, most of the fighting happened at alt below 3000m.

 

Apologies that is what I meant DOH! :D

[Krupi]

Better sustained climb generally translates into better acceleration. Getting faster sooner is more important in a low-level furball than top speed, which means that the same guys who loooove their 109K because they can easily win in a dogfight where the other guy fights their fight (instead of forcing the fight on their own best terms) may well be thinking about switching to the Spit.

 

cheers

 

horseback

 

+1

 

I do agree that the diving will be a potential issue obviously! :smilewink:

[DB 605]

Actually it appears that the Spitfire will beat even the 109 climb.

 

Spitfire IX +18lbs 4200 ft/min

 

109 with MW50 3563 ft/min

 

Bit strange, i have always been under impression that only Spit XIV (of all ww2 fighters) could beat K4 at climb performance. That's also stated by many books. Anyone got proper comparo charts about this?

[Krupi]

Bit strange, i have always been under impression that only Spit XIV (of all ww2 fighters) could beat K4 at climb performance. That's also stated by many books. Anyone got proper comparo charts about this?

 

 

http://www.spitfireperformance.com/spitfire-IX.html

 

I also thought the 109 had the edge! :huh:

Edited November 10, 2016 by Krupi

[DefaultFace]

Not sure where the climb figure you're mentioning comes from but sounds more like an early/mid G model. 3563 fpm comes out to about 18m/s and the K4 definitely does more than that in DCS.

 

Did some digging and found these. Comes out to about 4330 fpm for a K4 with DB605 DB at 1.8 ATA. Looks like they will have fairly comparable performance.

 

 

[zerO_crash]

Realistic or not we will never know. Both are pc programs for a home computer hehe. While probably less sophisticated in handling detail, war thunder will give very accurate kinetic performance relevant for speed and altitude evolution during combat etc.

 

~1100 spitfire IX were imported, not spitfire V. Problem is they were ~100 kmh slower then something like a la7 or d9 or k4.

 

Coming here with a impression that both are pc programs and therefore equally uncertain as to aircraft performance. Well, not really going to comment on that, you have a lot to understand about DCS and their quality assurance, that`s for sure. Funny you even compare them :megalol:

 

As a matter of fact, we do know, there are charts and tests, don`t mix up a sim with a game. I see you mention speeds related to performance, without giving enough detail. Well, Spit/Dora at top speed have a difference of approximately 74km/h. And less than that compared to a K4 (roughly 45-50km/h). K4 =/= D9 speed, Dora will be faster at their optimum. So the fact that you claim Spit being 100km/h slower than "K4/D9" is just wrong.

Edited November 10, 2016 by zerO_crash

[Krupi]

Not sure where the climb figure you're mentioning comes from but sounds more like an early/mid G model. 3563 fpm comes out to about 18m/s and the K4 definitely does more than that in DCS.

 

Did some digging and found these. Comes out to about 4330 fpm for a K4 with DB605 DB at 1.8 ATA. Looks like they will have fairly comparable performance.

 

 

 

The figure came from the DCS website I linked it, I did think that it sounded too low!

[rel4y]

The DCS K4 with MW50 does around 25 m/s at MSL. It looks rather like the following. The Dünnblattschraube only influences level speed, as seen in the high speed tests of the same document.

 

 

If comparing 18 and 25 lbs boost for the spitfire one should be careful which test he looks at. There were several different test runs done with JL.165. The Hucknall one should not be cited as some sort of 160 octane fuel was used which never saw war service and we dont know the composition nor lean octane rating. The A&AEE test is much more significant as done with standard 150 octane wartime fuel, though also not fully in operational config, but very close. Especially the blanking plate will have significant influence.

 

General. The aircraft was a normal Spitfire F.Mk.IX. The following were the chief external features:-

 

Two 20 mm. Hispano guns with sealed muzzles.

Two 20 mm. gun stubs with hemispherical fairings.

Four .303" Browning guns, ports sealed. Ejection chutes sealed.

Internal bullet-proof windscreen.

Circular rear view mirror, with hemispherical fairing.

Multi-ejector exhaust manifolds.

Aerial mast.

New tropical pattern air intake without gauze, but blanking plate installed.

No ice guard fitted in air intake.

 

In relevance to the DCS spit level speed charts may look something like the red line. Mind this may be rather on the optimistic side, but good enough for an impression. See here an original doc for reference http://www.spitfireperformance.com/merlin66_18_25b.jpg.

 

 

Looking at climb rate the expected change should look something like this, while the absolute values are a bit on the low side. The real values should look something in between this (at 18 lbs) and the BS 543 test, as for BS 543 again some changes were done such as sealed gun ports and using some weirdo prop. Also take a look at how the radiator settings influence climb rate, quite impressive (~2.5 m/s).

 

Edited November 11, 2016 by rel4y

[Friedrich-4B]

Has anyone bothered reading Yo-Yo's original post?:

 

The Spitfire development was started by obtaining a lot of original materials including wind tunnel tests, flight tests measurements, prop (we use wooden Rotol in the model) wind tunnel tests. Wind tunnel tests both for the prop and the airframe were performed for high Mach numbers as well.

So, the parts of the FM (airframe, prop, radiators) were carefully tuned separately to get the specified parameters of the real prototypes. Then, the blower of the existed V1650-7 engine was changed to fit Merlin 66 gear ratios, the automatic shift was set to new pressure.

 

Clearly Yo-Yo has accessed far more material than a few charts off the internet, for the Spitfire L.F. Mk. IX (and the Bf 190K-4), which is why DCS's IX should have performance figures that match production aircraft, rather than any one individual Spitfire.

 

As it is, all of the other performance "issues", such as the K-4's ROC have been discussed, at length (ad nauseum in some cases), for the relevant FMs, so quite why they have to be re-litigated here is a little unclear.

[Kurfürst]

Surely at that point you'd be low on fuel yourself? It's not like the MW50 replaces your normal petrol, indeed it works because it allows you to burn more of the stuff! Fuel capacity of the two planes isn't particularly different: 88 gal for the 109, 85 gal for the Spit, and the 109 has a much bigger displacement engine delivering more power, which makes higher fuel consumption a certainty (unless the Merlin was abnormally inefficient, and I've seen nothing that suggests that was the case).

 

It was just a quick reflection of "running out of MW" suggestion, so I run a bit of number crunching to see how viable it would be in DCS. Well, not very much.

 

As for the engine, the Merlin is not very economical to be honest, its a very hungry little wasp with a lot of supercharging going on at rather low compression ratios and higher RPMs to compensate for the lower displacement. Its all about producing power and not at all about fuel efficiency. In modern engine marketing terms, you could call it a "downsized" engine vs a "rightsized" engine, but its feels a rather odd description for something that weights almost a ton and displaces some 27 liters. :D

 

Now as for the number crunching, in the Spit IX LF, you 85 gallons being consumed by the Merlin 66 at 150 gallon per hour rate when at full +18 boost. This means running it flat out all time would let you run the engine for 34 minutes or so.

 

In the 109K-4, you 88 gallons (i.e. 400 liters) of avgas being consumed by the DB 605DB at 610 liter (134 gallons) per hour rate when at full 1,8 ata boost, plus you have the 85 liter MW tank, the contents of which being injected at a rate of 180 liter hour. The MW tank is thus dry after 28 minutes, but you still have about 100 liters left (I think this was intentional, as the "red fuel lamp" on the 109 would light up at 100 liters, signalling you need to RTB). At this point the IXLF has about 14 gallons left in the tank, or about 5 minutes worth, so its high time to look for a suitable landing place or you will soon do so as a glider.

 

100 liters is enough for about 12 minutes of operation at the max allowed 30 minutes rating once MW runs out - and on that rating the 109K can still match the IX LF speed at full output, and is in fact still quite a bit faster at the very high altitudes, like 700 and over.

 

Of course all this is very very theoretical, since nobody flies likes this, and no fight should last for like 30 minutes... and at constant full power, and fuel tanks cant be emptied either for the last drop of fuel. But the bottomline is, you definitely can't bet on him running out of MW fluid.

[flare2000x]

Even if the Spitfire can climb at a faster FPM, it does so at a lower airspeed. This would be a disadvantage, right? The 109 could extend away from a chasing Spitfire. Although if the Spitfire was on defence it could climb steeper?

 

I hope the Spit ends up being a competitive aircraft. I love it so much.

[rel4y]

Climb speed was usually measured at 170 mph (~270 kph) up to around FTH. The K4 climb speed figures are usually for 260 -280 kph, while the Finns achieved better climb results at ~300 kph but with closed radiator. I would say there shouldn't be much difference. Higher up the spit should outclimb the 109 due to lower wingloading. This means climb advantage of the 109 diminishes with altitude.

[Nerd1000]

It was just a quick reflection of "running out of MW" suggestion, so I run a bit of number crunching to see how viable it would be in DCS. Well, not very much.

 

As for the engine, the Merlin is not very economical to be honest, its a very hungry little wasp with a lot of supercharging going on at rather low compression ratios and higher RPMs to compensate for the lower displacement. Its all about producing power and not at all about fuel efficiency. In modern engine marketing terms, you could call it a "downsized" engine vs a "rightsized" engine, but its feels a rather odd description for something that weights almost a ton and displaces some 27 liters. :D

 

Now as for the number crunching, in the Spit IX LF, you 85 gallons being consumed by the Merlin 66 at 150 gallon per hour rate when at full +18 boost. This means running it flat out all time would let you run the engine for 34 minutes or so.

 

In the 109K-4, you 88 gallons (i.e. 400 liters) of avgas being consumed by the DB 605DB at 610 liter (134 gallons) per hour rate when at full 1,8 ata boost, plus you have the 85 liter MW tank, the contents of which being injected at a rate of 180 liter hour. The MW tank is thus dry after 28 minutes, but you still have about 100 liters left (I think this was intentional, as the "red fuel lamp" on the 109 would light up at 100 liters, signalling you need to RTB). At this point the IXLF has about 14 gallons left in the tank, or about 5 minutes worth, so its high time to look for a suitable landing place or you will soon do so as a glider.

 

100 liters is enough for about 12 minutes of operation at the max allowed 30 minutes rating once MW runs out - and on that rating the 109K can still match the IX LF speed at full output, and is in fact still quite a bit faster at the very high altitudes, like 700 and over.

 

Of course all this is very very theoretical, since nobody flies likes this, and no fight should last for like 30 minutes... and at constant full power, and fuel tanks cant be emptied either for the last drop of fuel. But the bottomline is, you definitely can't bet on him running out of MW fluid.

Makes sense that they would allow enough MW50 for a full interception, seeing as it was needed for full performance.

 

Interesting that the Merlin is so thirsty- I guess that's the price of using lots of supercharging to get your power rather than increasing displacement and compression ratio. Massive speculation here, but I'm guessing they kept compression ratio the same to avoid re-designing the pistons and cylinders: keeping them the same means less re-tooling, and R-R were always under more demand for engines than they could supply (hence the Packard deal).

[Alicatt]

Makes sense that they would allow enough MW50 for a full interception, seeing as it was needed for full performance.

 

Interesting that the Merlin is so thirsty- I guess that's the price of using lots of supercharging to get your power rather than increasing displacement and compression ratio. Massive speculation here, but I'm guessing they kept compression ratio the same to avoid re-designing the pistons and cylinders: keeping them the same means less re-tooling, and R-R were always under more demand for engines than they could supply (hence the Packard deal).

 

Now that is a subject that I have experienced first hand, not with a Merlin but with a Ford 4.6l V8 Mod motor that has been supercharged.

 

A few cars like mine have been supercharged and by a specific garage that did a lot of tests to get the optimum point between power and reliability, my car went from 239bhp to 398bhp at the rear wheels, but if you look at the fuelling map you will find that it runs very rich compared with tuning for max power.

 

Some other people with the same type of car and engine went down a home built road to get a bit of a cheaper solution, the bought a kit from the supercharger manufacturer and had the installation done at a saving of about £1.5k they used the standard map for that engine/supercharger combination that works in the USA.

 

But with the different fuel (Lower octane in EU) and higher speed limits in Europe those engines failed especially on the Autobahns in Germany where a lot of running was done at large throttle openings and high speed those engines failed due to overheating and seizing.

 

My own car has done many miles on the Autobahn and at speeds up to 180mph and has been very reliable, but it does use slightly more fuel than the other cars that were not done by the same garage.

 

So using excess fuel to keep the engine cooler and give it a longer life is a valid technique.

 

My supercharged 4.6 V8

[Nerd1000]

Now that is a subject that I have experienced first hand, not with a Merlin but with a Ford 4.6l V8 Mod motor that has been supercharged.

 

A few cars like mine have been supercharged and by a specific garage that did a lot of tests to get the optimum point between power and reliability, my car went from 239bhp to 398bhp at the rear wheels, but if you look at the fuelling map you will find that it runs very rich compared with tuning for max power.

 

Some other people with the same type of car and engine went down a home built road to get a bit of a cheaper solution, the bought a kit from the supercharger manufacturer and had the installation done at a saving of about £1.5k they used the standard map for that engine/supercharger combination that works in the USA.

 

But with the different fuel (Lower octane in EU) and higher speed limits in Europe those engines failed especially on the Autobahns in Germany where a lot of running was done at large throttle openings and high speed those engines failed due to overheating and seizing.

 

My own car has done many miles on the Autobahn and at speeds up to 180mph and has been very reliable, but it does use slightly more fuel than the other cars that were not done by the same garage.

 

So using excess fuel to keep the engine cooler and give it a longer life is a valid technique.

 

My supercharged 4.6 V8

The other thing to note is that the supercharger itself takes energy to run- if you make it bigger (for more power) you must burn more fuel to turn it. Now the compression stroke of the engine does the same thing, but the power cost of a higher compression ratio is balanced by the larger expansion ratio that goes along with it, so a higher compression ratio usually gives better economy (thanks to higher combustion temperature and more expansion) along with more power.

 

On the other hand, upgrading the supercharger (and applying MOAR BOOST!) is probably the quickest way to extract more power from an engine, so that is what Rolls-Royce did. The results speak for themselves: the Merlin, in spite of its relatively small displacement, was able to compete with much larger engines right up until the end of the war though as we can see this approach wasn't great for fuel economy. As a point of reference, the Bf109's DB605 displaces 35L to the Merlin's 27L, making it more comparable to the 37L Griffon in size (though the Griffon is around 150kg heavier than the 605- don't ask me how DB made such a large engine so light).

[Kurfürst]

The other thing to note is that the supercharger itself takes energy to run- if you make it bigger (for more power) you must burn more fuel to turn it. Now the compression stroke of the engine does the same thing, but the power cost of a higher compression ratio is balanced by the larger expansion ratio that goes along with it, so a higher compression ratio usually gives better economy (thanks to higher combustion temperature and more expansion) along with more power.

 

On the other hand, upgrading the supercharger (and applying MOAR BOOST!) is probably the quickest way to extract more power from an engine, so that is what Rolls-Royce did. The results speak for themselves: the Merlin, in spite of its relatively small displacement, was able to compete with much larger engines right up until the end of the war though as we can see this approach wasn't great for fuel economy. As a point of reference, the Bf109's DB605 displaces 35L to the Merlin's 27L, making it more comparable to the 37L Griffon in size (though the Griffon is around 150kg heavier than the 605- don't ask me how DB made such a large engine so light).

 

Exactly. And its no small power when it comes to driving that supercharger - the Griffon for example, noted for its very powerful supercharger, used some 600 horsepower (yes, SIX hundred) just to run the supercharger at full speed. Other may have used less, but its still in the hundreds of horsepower digits.

 

Now, quite typically for a WW2 engine, fuel consumption was around 235 grams/HP/h, in other words just to drive the (Griffon) supercharger you are burning 0,235 kg/HP/h, or 140 kg (cc. 185 liter) of fuel every hour. Just for the supercharger, because the driving the prop consumes the rest.

 

You are entirely correct that very high levels of supercharging is a very straightforward way to increase power. But it comes at a cost higher fuel consumption (meaning that you have to carry more fuel) and on the long term because of dimenishing returns and efficency

 

When you are using high boost rates, you would probably want to stick to lower compression ratios (which again are not so good for engine effiency, as for the same amount of fuel burned, there is less useful mechanical work), to avoid extreme end pressures that your fuel cannot take without detonation. After a while you probably want to use higher lead content or aromatic fuel for the same reason, which leads to to deposits and corrosion in the engine.

Sooner or later you will also need some sort of intercooling (and the drag and weight of the intercooler radiators and plumbing associated with it) to deal with the extreme heating up of the charge in supercharger itself (again leading again to fuel detonation).

 

Which is probably the answer why the DB engines are lighter and more fuel efficient BTW - they tended to operate at moderate supercharging (the large volume needed rather less boosting), using rather high compression ratios and did not used intercoolers at all (apart from the similar MW injection on later models). A designer has to weight all that. There is no point in an engine developing twice the horsepower if its increased weight (of the whole powerplant - inlcuidng fuel reserves, radiators, oil tanks, propellor size and weight) and size leads to such an increase in drag that the net gain in thrust is marginal, or not there at all.

 

Designing a new, larger block and making it work reliably is a matter of many years, and in wartime, you do not have the luxury of waiting for a new block. In wartime, you have to make the most out of the existing one and keep it competitive.

[flare2000x]

Obviously you're never going to be running at max combat RPM and boost all the time though. The Spit has a nice big wing to keep you up so you can bring the power way down and stay flying if you just want to cruise or loiter.

[Captain Orso]

8<

don't ask me how DB made such a large engine so light).

 

It's a Daimler-Benz, what else would you expect? :lol:

As a Benz-Town resident, I just couldn't resist