CoD Spit Mk.I 100 oct vs. Real World Spit Mk.Ia +6 lbs
 

Hey guys

Did a comparison of the in-game Spitfire Mk.I at 100 octane to the real world data on a Spitfire Mk.Ia at +6 lbs.

Again, I am no Spitfire expert, so correct me if I am wrong, but isn't the real world +6 lbs. Spitfire using 87 octane? If so, shouldn't the in-game 100 octane (i.e. +12 lbs.) version be faster that the +6 lbs. below the FTH?

In either case, for those who have tested the in-game version, what values are you coming up with? Reason I ask is I have been reading some posts where some are saying the mixture levers and such may be reversed or not working at all in this beta version. So, there is a good chance that I did something wrong during the test. If you guys are getting it to go faster, could you post the settings you used during your tests? If not, than it may be best to hold off on any further testing until 1C has a chance to sort out these issues.

It just seems odd to me that the 100 octane version is not faster than the 87 octane version below FTH. Note I also included a picture of the in-game Spitfire Mk.I at 100 octane to the real world data of a Spitfire Mk.Ia at +12 lbs. To show how much slower the in-game Spitfire Mk.I at 100 octane is below the FTH.

Got a new test for you , if you would in realisim settings under CEM shut off engine temp mang. i think you will be surprised by findings . As they seem to be much closer to whats right tad off here an there depending on plane . I an others would be interested in your findings :grin:

Well..

Right now I am spending more time on my web-page than testing..

I just did a few quickie tests to make sure the file formats are working and to have some data to work with..

Over the past 10 or so years of doing IL-2 FM testing I realized something..

I don't have the time to do all the tests people would like to see done!

So I had the idea of making a web-site where people can do their own test, upload the data and display/graph it..

Not only graph the results of their CoD test, but compare the CoD results to the real world data of their choice..

And not just ROC and TSPA tests!

For the CoD in-game test data, you will be able to pick and choose the 'variables' you want to graph. For example, say you want to graph the oil temperature vs. altitude, or oil temperature vs. water temperature.. Basically any in-game variable. And if you find a real world test that has say water temperature, you would be able to compare the CoD results to those.

With that said, I am also working on a 'standard form' for people to submit the real-world-data they want to use for comparison.. Also working with FST to come up with a standard C# script for testing.

So, hopefully in the next few weekends 'you' will be able to do this test your talking about and upload it to my website.

with which weapon configuration(s) and with which ammo load(s) did the RL-tests take place?

Perhaps I am not understanding the question fully, but all Spit Ia's at +6.25psi boost (full throttle) should go the same speed whether they are using 87 or 100 octane. The Spit 1a 100 octane has the ability to use +12psi (using the modified boost cutout red tab) and go faster (provided it is below FTH for +12psi). There is an intermediate altitude range where the supercharger can give less than +12psi but more than +6 psi, above that 87 and 100 octane variants are equal.

I assume your flight tests for the CoD Spit 1a 100 octane were using the +12psi boost? Did the engine blow up during tests?

The RL data for a mk I (if it's the data usually quoted, top speed 363mph) was taken from a Spitfire that was at least 300 lb lighter than a mkI in Battle of Britain trim. It was around 5,800 lb as opposed to 6,100 lb (ish). It was the eight gun version, didn't have the pilot armour, bullet proof windscreen ( reckoned to cost 3-4 mph) or the IFF aerial (again another 2-3 mph). The only reference I've seen to it is by Dr Alfred Price. He says in "Spitfire in combat" that the top speed was closer to 350 mph for a BoB era MkI. It's a bit vague, I know, but does highlight how difficult it is to get accuracy. He knows his Spits though..

According to this the Spitfire should be 28 to 34 mph faster below FTH (10,000ft)

http://i91.photobucket.com/albums/k3...spit1-013a.jpg

So, VERY roughly the power curves could have looked something like:

http://i91.photobucket.com/albums/k3...reMkI6lbsa.jpg

Alfred Price: The Spitfire Story, Haynes publishing 2010:

http://i91.photobucket.com/albums/k3...-page-003a.jpg
http://i91.photobucket.com/albums/k3...e-page-002.jpg
http://i91.photobucket.com/albums/k3...e-page-002.jpg

Nope, probably not the Spitfire, but the Hurricane.

I have yet to see a single +12 Spitfire Mark I performance trial.

Since Merlin XII is mentioned in one of the previous paragraphs, it would be not so easily determined. Might as well be Spitfire, not necessarily Hurricane. Difficult to say from a single document page.

Also, if the determined speed increase of the Hurricane airframe would be 28/34 mph, it would be probably even more on a Spitfire due to better aerodynamics, don't you agree?

A quote from "Spitfire in combat" Dr. A. Price

'In Spring 1940, in a bid to further improve fighter performance, the RAF introduced 100 octane petrol in place of the 87 octane fuel previously used. In the case of the Merlin II and III engines fitted to Spitfires, this gave no improvement in performance at or above the engnes' full-throttle altitude of 16,500. Below that altitude however the new fuel gave a valuable increase in power. Supercharger boost could be increased from +6.5 lb to 12lb. That increased the Spitfires maximum speed by 25mph at sea level and 34 mph at 10,000 feet....

(he then goes through a list of modificatons that cost the Spitfire speed)

.....The maximum speed usually quoted for a Mk I is 362 mph @:18,500. But that figure reffered to K9787, the first production aircraft during it's initial performance tests in 1938 at an AUW of 5,819lb. By the summer of 1940 the maximum speed of a fully equipped Mark I was somewhat lower, about 350 mph at the same altitude'.

My personal opinion is that the in-game Mk I should be hitting around 350/360 mph depending on loadout @18,500 feet. It's also a shame that the same sort of info doesn't seem to exist for other types in the game.


EDIT: List of some of the modifications between K9787 and a BoB era Spit I that cost speed

73 lb's worth of pilot's armour
Bulletproof windscreen (cost around 6mph aerodynamically)
3mm armour plating for the upper fuel tank
IFF Aerials (cost another 2-3mph aerodynaically)

Total weight of above mods 335 lb.

The constant-speed propeller on N3171 made a big difference in take-off distances (225 vs 320 yards, 370 vs 490 to clear 50 ft screen) and rate of climb. N3171 was fitted with the windscreen, 3mm alloy sheet (not armour) over the fuel tank and domed canopy. Once fitted with armour and IFF the rate of climb would have gone down as would the top speed.

That aside the real problems still lie in CLOD performance below 10,000 ft using +12 lbs boost, which has not been modelled properly:

http://i91.photobucket.com/albums/k3...reMkI12lbs.jpg
© ACE-OF-ACES INC. 2012

A link is provided to the source of the real world test at my website, i.e.

www.flightsimtesting.com

There you will find the answer to all those questions and more.

Ok, lets see..

Agreed.. So far so good..

Correct.. So far so good..

Agreed.. That is what I was refering to when I said..

Yes! ;)

Nope! ;)

On that note..

Differences in weight typically affect the ROC results much more than the TSPA results..

That is to say you may not notice a difference (percent difference would be small) in TSPA due to a little weight change, but, you will notice it in an ROC test.

True, and when you take into account that the first production batch had a take-off run of 420 yards, there's a reduction of almost 200 yards. Rate of climb to 20,000 fell from 11 min 18 sec to 7 min 42 sec, and max speed increased by 4 mph simply from changing the prop. And yes, there seems to be a distinct lack of 'oomf' low down.

Sometimes I get the feeling that with Spitfire's there's too much information!
It's always the centre of attention. Never seen a 93 page thread on a hurricane or 109.

Wait until I upload my 109 and 110 testing! ;)

okay, I just wanted to know. Thank you!

I'm still afraid of people being awful "test pilots" like those who were around at CoD Release... of that type who complained hard, over multiple forum pages, about why they can't achieve maximum rated speed at sea level (TAS was totally unknown, anyways). If the devs would have listened to that, we would be in even more trouble now.
But you guys seem to have done your "homework" resp. proper set-up and flight procedures (wind/no wind, REALLY straight and level, eliminate any yawing etc.), and then some (that website I was directed to looks really nice)!

Thanks it is a work in progress but it is comming along! S!

It does not do any good to model an aircrafts speed, climb, and turn performance but not reproduce it's flying qualities.

You are not "simulating" anything.

But the correct speed, climb and turn performance are a good start to the ''simulation'' process, are they not?

Depends...

Right now the relative performance is pretty much spot on. The margin of error is pretty much the same across the board for all the major SE fighters.

If you go increasing one airplane model so that it's margin of error is reduced, then the balance is upset.

Especially if you go making some fantasy airplane with the raw performance numbers that is unrealistically stable.

I see what you're saying but unfortunately it seems that it's especially the relative performance is way off to start with. There would be far less complaints if what you stated would be true.

I agree that the flying qualities (incl. stability) are just as important and should be adjusted in the same time. Let's see what we'll get in the next patch...

Not a good start..

A must have!

In that getting the performance right is the 'basics'..

Nothing else maters without the basics being right in a simulation!

I mean what good is it if the simulated 'buffet shake' flying qualities is historically correct if the stall speed at which it occurs is simulated incorrectly!

nice graphs.

Any chance of the same graph for the hurricane or 109/110?

For a flight simulator...yes, if you goal is to simulate one airplane in isolation.

This is a game that is trying to simulate air combat.

In the context of an air combat simulator, it would be completely unrealistic and over modeled. The airplane would outclass the opposition when it was equal to it historically.

Agreed 100%

As for the rest, not so much

Maybe you should petition Microsoft? There are plenty of FSX websites still up and running.

Thanks!

Hopfully soon..

Right now my focus is on providing the tools for testing.

If I don't have to fly out to CA next week I should get some free time to work on it next weekend

Stay tuned! S!

Well.. looks like Ill be in CA for a week or two.. Ill be busy with the acceptance testing of some new multi million dollar hardware we just bought.

The software portion (that I am writing the interface too) is not until later in the week

So as long at there are no big surprises, as in their software interface document does not work as advertised, which in turn causes me to make a lot of changes.

Than I should have some time to work on my IL-2/CoD performance testing web tools next week.

Well..

Turns out their software was in real bad shape.. Their documentation was even worse!

I spent most of my time working with their software group to fix their problems..

That and I had to write a couple of hardware test programs in the evenings for testing the next day..

So long story short, working a 13hr+ days for 7 days straight didn't leave much free time to work on my CoD performance testing web based tools..

Hopefully next weekend!

I an others would be interested in your findings

http://www.gqth.info/0.jpghttp://www.gqth.info/7.jpghttp://www.gqth.info/8.jpghttp://www.gqth.info/9.jpghttp://www.ymeu.info/test5.jpg