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-   -   Aircraft peformances, is this joke ? (http://forum.fulqrumpublishing.com/showthread.php?t=33396)

winny 07-23-2012 01:44 PM

Quote:

Originally Posted by jf1981 (Post 447616)

In my opinion, we should have the right performance without use of bost cutout, up to my understanding. Octane grade 100 was probably also not available in 1938 for the Mk I prototype. The prototype itself fit with a wooden fixed pitch propeller reached 349 mph TAS at 17'000 ft.

I'll try to get more accurate datas from one of the big books I have related to Spitfire, a very good and complete one indeed. Those are interesting lecture.

Edit
I find no information supporting that the max speed of Mk I & II were measured with more than the rated power at 6 psi of boost.
Apparently the Mk I had 1030 bhp at altitude (either 16,250 or 17,000 ft ?) and Mk II 1150 bhp at 14'500 ft, source "The story of the spitfire" book.

I can add some more to this, the figure that is usually quoted for a MK I Spitfire is 362mph at 18,500. This was referring to K9787, the first production Spitfire, in 1938.
Between then and the BoB there were some substantial modifications that lowered the top speed. A 73 lb armoured plate, bullet proof windscreen, 3mm of light alloy covering for the top of the upper fuel tank, installation of the IFF etc..

The AUW of K9787 was 5,819 lb, the AUW of a BoB period Mk I was around 6,115 lb.

There were also aerodynamic penalties, the IFF aerial was reckoned to cost 2 mph, the windscreen cost upto 6 mph. The top speed of a fully equipped Spitfire in Battle of Britian trim was closer to 350 mph at the same altitude.

Sources - Spitfire The History and Alfred Prices Spitfire in Combat

ATAG_Snapper 07-23-2012 02:30 PM

Quote:

Originally Posted by tintifaxl (Post 447650)
I would call that glitching. Should be instant kick on a server. :-P

Ha!

In fairness, the same can be said for those dastardly Red pilots that fly with canopies open (ie. "sonar") to listen for those 109 pilots sneaking up from behind. None of whom continuously use their WEP buttons, of course! ;)

Bewolf 07-23-2012 02:37 PM

Quote:

Originally Posted by ATAG_Snapper (Post 447681)
Ha!

In fairness, the same can be said for those dastardly Red pilots that fly with canopies open (ie. "sonar") to listen for those 109 pilots sneaking up from behind. None of whom continuously use their WEP buttons, of course! ;)

What about those 109 pilots that jettison their canopies to get an even standing (or simply open their side windows)? <: )

ATAG_Snapper 07-23-2012 02:55 PM

Quote:

Originally Posted by Bewolf (Post 447682)
What about those 109 pilots that jettison their canopies to get an even standing? <: )

A plague on all of us!!!! LOL

My ultimate wish for Cliffs of Dover? That Ilya would approach IvanK with the sole wish of resolving the FM issues once and for all for EVERY a/c, including bombers. IvanK would be free to pick whomever he wanted from this community to assist -- but he has Final Say. Ilya could send IvanK periodic (ie. FREQUENT) betas dealing with FM adjustments only...along with readme files (a nice thing to have)....with adjustments based on IvanK's input on the prior FM Betas. Once IvanK signs off on the final FM Beta, then that's it. Done. IvanK is given a nice Morris roadster for his trouble, and we can then move on to quibble about hedgerows vs tree-lined lanes after that.

Or how much the tachometer needle should jitter......(uh oh, shouldn't have said that.....:rolleyes:)

Bewolf 07-23-2012 03:09 PM

Quote:

Originally Posted by ATAG_Snapper (Post 447687)
A plague on all of us!!!! LOL

My ultimate wish for Cliffs of Dover? That Ilya would approach IvanK with the sole wish of resolving the FM issues once and for all for EVERY a/c, including bombers. IvanK would be free to pick whomever he wanted from this community to assist -- but he has Final Say. Ilya could send IvanK periodic (ie. FREQUENT) betas dealing with FM adjustments only...along with readme files (a nice thing to have)....with adjustments based on IvanK's input on the prior FM Betas. Once IvanK signs off on the final FM Beta, then that's it. Done. IvanK is given a nice Morris roadster for his trouble, and we can then move on to quibble about hedgerows vs tree-lined lanes after that.

Or how much the tachometer needle should jitter......(uh oh, shouldn't have said that.....:rolleyes:)

Wish it was so easy. You know this community. Whatever numbers the gents from Maddox Games put in here, there will always be somebody with a chart trying to prove them wrong, does not matter blue or red or pink or whatever.

That has such a long history that I don't know what to believe anymore anyways and just fly the damn things as they.

ATAG_Snapper 07-23-2012 03:54 PM

Ain't that the truth!

The reason I specified IvanK is because I believe his judgement would be respected by both sides. They may not agree with certain aspects, but he certainly represents himself as even-handed and knowledgeable with both LW and RAF aircraft. As it stands now, the devs seem incapable or unwilling to apply hard data into credible Flight Models. Witness the ongoing RAF fighter debacle that has gotten progressively worse with each CoD iteration, per my earlier post. Certainly both LW and RAF aircraft need serious FM overhauls, including fighters of either side that can actually exceed 30,000 feet!

As it stands now, it would appear that the devs cannot deliver aircraft that either side can accept in terms of FM's, unless they enlist and heed someone such as IvanK to put things right.

Bewolf 07-23-2012 06:08 PM

Quote:

Originally Posted by ATAG_Snapper (Post 447700)
Ain't that the truth!

The reason I specified IvanK is because I believe his judgement would be respected by both sides. They may not agree with certain aspects, but he certainly represents himself as even-handed and knowledgeable with both LW and RAF aircraft. As it stands now, the devs seem incapable or unwilling to apply hard data into credible Flight Models. Witness the ongoing RAF fighter debacle that has gotten progressively worse with each CoD iteration, per my earlier post. Certainly both LW and RAF aircraft need serious FM overhauls, including fighters of either side that can actually exceed 30,000 feet!

As it stands now, it would appear that the devs cannot deliver aircraft that either side can accept in terms of FM's, unless they enlist and heed someone such as IvanK to put things right.

It "could" work this way. Clearly lots of stuff has to be revised. I think one major problem with altitudes, however, is the lack of propper high altitude atmospheric modelling. I remember a post by Luthier stating that this will come with the sequel.

Funny, they will implement it with a low level combat scenario.
That said, imho, everything making airplanes work in the first place should be fixed with priority.

Does not make much sense to have a propper speeding Spitfire when the Bombers can't level bomb due to Lofte issues to begin with. A Me109 with real life climb speed won't be much of an achiecement if the Hurricane can't even get it's engine started.

Too many basics have to be fixed first before going into fine tuning. But that is just my personal stance.

jf1981 07-23-2012 06:16 PM

Quote:

Originally Posted by winny (Post 447670)
I can add some more to this, the figure that is usually quoted for a MK I Spitfire is 362mph at 18,500. This was referring to K9787, the first production Spitfire, in 1938. [...]

This is right

Prototype K5054 1050 bhp at 16'000 ft at 3000 rpm 6 1/4 psi boost reached nearly 350 mph.

Merlin II engine was 1050 bhp at 6.25 psi boost (octane 87) and 1300 hp at 12 psi boost (octane 100) but shortening lifetime by a factor of 10 (100 hours to 10 hours).

-------------
Mk I

Martlesham Heath, 6 january 1939. K9787. Merlin II performance trials.
Cruising 318 mph @ 15'000 ft
Max spd 362 mph @ 18'500 ft
6.5 min to 15'000 ft (2300 fpm mean)
22.4 min to 30'000 ft

-------------
Mk I
May 1939
295 mph @ 1'000 ft
276 mph @ 20'000 ft
(I assume this is IAS)
-------------
Mk II

Spitfire serial K9788 was tested with merlin XII (the Mk II engine) with following results :

Boost 7 lb 366 mph @ 18,900 feet
Boost 9lb 369 mph @ 16,700 feet
Boost 12 lb 372 mph @ 13,450 feet

Blackdog_kt 07-23-2012 06:18 PM

Quote:

Originally Posted by jf1981 (Post 447621)
Leannig purpose to keep air fuel mixture to 1/15, when climbing, the less dense air means it comes to 1 of fuel for less than 15 of air in ratio, in other words, too rich of fuel, so less efficiency, some fuel is burnt meanlessly.

However as explained there's a temperature issue, generally, when the leaning is done manually, full power with rich mixture expect at very high altitude where some leaning may be needed.

When cruising one can lean further.

Except if the sim has a sort of bug, no full power should be done with lean but if one wants to shorten an engine's life. Maybe they'll model an engine failure due to incorrect leaning.

Obiously, a lot of fuel consumption reduction achieved at altitude in lean mixture, could be 20% less. I seem to remember the spit was giving 40 gph rich and 35 gph lean by 15'000 ft.

What you say is correct, with the only difference that the RAF fighters have auto-lean and auto-rich mixture. The Hurricane seems to be manual in the sim but it should be the same as the Spitfire, maybe it's just an animation error on the lever and it is in fact only two settings?

In any case, here's the short version from wikipedia:
http://en.wikipedia.org/wiki/File:Id...ichiometry.jpg

According to that graph the best air/fuel analogy for rich is 12.6:1 and for lean 15.4:1.
What the semi-automatic mixture controls do is they try to maintain these ratios, the pilot only selects if he wants rich or lean.

It is very clear however from the graph that there should be a difference in power and fuel consumption, just like you say ;)

Quote:

Originally Posted by ATAG_Snapper (Post 447628)
Per Redroach's post above, the Spitfires have the mixture control incorrectly reversed in Cliffs of Dover. The Hurricanes have the mixture control modelled correctly: Pull backwards for Rich, push forward (toward the instrument panel) for Lean.

So, the Spit mixture controls are currently modeled like US and general aviation designs (rich is forward)? Good to know, because i thought that lean is forward and i was wondering why it's easier to start on "lean". :-P

jf1981 07-23-2012 06:48 PM

Quote:

Originally Posted by Blackdog_kt (Post 447732)
What you say is correct, with the only difference [...]

Yep I was'nt entering into details because I was'nt sure if it was fit with auto rich/lean.
Thank you.


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