Mixture: All Brit fighters tested

[Torian]

Just gonna copy and paste my post from the ATAG forum here for those who may find it interesting.

OK, Testing done, my findings are:

DH Hurricane.....mixture is back to front, full rich is all the way forward, lean is all the way back....might be why the DH is a pain to start, get lever all the way forward when u push throttle forward.
Hurricane Rotol...modelled correctly
Hurricane 100oct...modelled correctly

Spitfire MkI....back to front...as per DH Hurricane
Spitfire MkIa...modelled correctly
Spitfire MkIIa...modelled correctly
Spitfire MIa_100oct...modelled correctly

Blenhiem MkIV...couldn't see any change. It flew just fine with the mixture where it should be, all the way back. In-game the mixture throttles are all the way forward at spawn.

Made a semi-dark early morning map and these findings are based on yellow and blue flames from the exhaust. If these are modelled incorrectly then all bets are off.
Not sure if it's absolutely needed but I found running the mixture throttle all the way up and down seemed to have a settling in effect after u takeoff (take that for what it worth, maybe nothing).
Now if this is all correct then it should help us with correct engine management and fewer burnt engines. There are other factors of course like rate of climb (keep at 180mph or above), radiator settings
(I aim for between 35 to 50% depending on what I'm doing aiming to keep engine temp under 110* water temp), prop pitch (the higher u go the coarser u will need to run it...been using 2400 when up at 16 to 19000ft) and throttle adjustment...u don't necessarily need hammer down all the time, proper engine management will require adjusting throttle to where it's needed.
Joining the Allied side means u are gonna need to learn how to fly. If u don't want to learn how to fly then get in a 109 E4 and just enjoy urself

[phoenix1963]

Good work, I emailed the same thought (but less comprehensively tested) to Sean (IvanK) because I had the same worry that he'd possibly overstated the problem for some aircraft.
He's in contact with Ilya.
Can Klem's measurement scripts give us the real mixture values?

56RAF_phoenix

[Torian]

Can Klem's measurement scripts give us the real mixture values?

I'm not familiar with this, can u give me a link ?
Thx

[phoenix1963]

http://forum.1cpublishing.eu/showthread.php?t=33661
At the top of the thread.
I've not had time to try it yet, but maybe there's a call that can be added?

56RAF_phoenix

[Torian]

Thx for that. Comparisons between CloD FM and real world performance is not really my bag and is being done by more competent folk than myself. I was just wanting clarification on that which we have been given and how best to work with it. I just wanted to know which way to push the lever to get the correct mixture and to let evry1 know which planes have it right or wrong.
I'm not sure whether that test script is coded to measure mixture setting or just record where it was set and that will be affected by which way Klem believed it was supposed to be going. ie if he has coded it believing all mixture is modelled back to front and has coded 100% as fully rich when in fact 0% is fully rich then performance results will be invalid. I'm only guessing at this as I have no idea but just thinking out loud. I will PM him and give him a link to this thread and he may be able to clarify things.

[klem]

Hi Torian,

you should have my PM now but for anyone else...

My Hurricane tests were done on Auto-Rich, i.e. lever 'back' where it should be.

For the Spitfire I forget exactly what I did because it was a quick and dirty knowing there was another patch to come. I do know now that the MkIa with 100octane and BCO currently is modelled so that the mixture has to be 'fiddled' with. It should be back at fully rich for all normal flying and tests (they fixed the forward/back issue so forward is now lean and back is now rich as it should be). In the latest patch, you have to adjust to lean when flying BCO which is not how it should be. It should always be auto-rich ('back') unless cruising on auto-lean for economy (with restrictions on boost and rpm).

I could add the mixture to the script but it shouldn't be necessary. As I said, it should be 'back' on auto-Rich for all tests and normal flying.

Hope that helps.

[phoenix1963]

...they fixed the forward/back issue so forward is now lean and back is now rich as it should be). In the latest patch, you have to adjust to lean when flying BCO which is not how it should be....As I said, it should be 'back' on auto-Rich for all tests and normal flying.

Wow Klem, this is yet another wrinkle because Sean's (IvanK) post seemed to be saying ALL the red mixture settings were wrong, rather than solely when using BCO.

The reason I put Torian on to you was that I hoped your scripts could be modified to show the actual mixture (I mean the fuel concentration rather than the control setting).

56RAF_phoenix

EDIT: IvanK's post is here http://forum.1cpublishing.eu/showthread.php?p=458227#post458227

[IvanK]

Happy to be corrected on any of this but what are you using to prove that Mixture is correctly modelled in a specific position ?
If someone can extract actual Fuel Flow from the FM for a specific Boost/RPM combination with different Mixture lever positions that would settle the manner once and for all. If Fuel Flow cant be extracted then change in weight would suffice... it would provide Fuel Flow in weight.


As stated the bottom line is all a RAF fighter pilot needs to do is have the mixture lever Fully back .. that Should give him AUTO RICH ... automatic altitude compensation no Boost restrictions.

[IvanK]

Based on Torian's findings I went off and did some flight tests to determine Fuel Flow versus mixture.

I stand corrected based on Fuel flow tests CSU Spits and Hurris have correct Mixture lever orientation, however Levers are incremental and should be 2 position only. Boost Cutout requires some Leaning of the mixture to ensure smooth operation ... incorrect should be AUTO RICH.

Method:
10 min level Flight stabilised at 10,000ft on QNH 1013 +- 50 feet throughout.
Power Fixed at +2/2400RPM
RAD Full open (to provide constant test setting)
Full CEM
Fuel Set to 20% in FMB
Note via Tool tip Fuel Remaining at start and at 10mins elapsed on Stop watch.

RESULTS

Spit IA
Mixture Lever Full Back
Fuel Used over 10 min 8 Gall
Fuel Flow 0.8Gall min

Mixture Lever as far Forward as possible ensuring Smooth engine operation (about 75% forward ... any further forward resulted in rough running)
Fuel used over 10min 6 Gall
Fuel Flow 0.6Gall min

Conclusion Moving Mixture lever forward is Leaning mixture.
Mixture lever not 2 Position but incremental (WRONG)
Boost Cut Out req mixture lever forward of 1/3 to Full forward (Wrong)

Spit 1A 100 Octane
Mixture Lever Full Back
Fuel used over 10 min 8 Gall
Fuel Flow 0.8 Gall min

Mixture Lever forward as far forward as possible to achieve smooth engine operation (about 75% forward ...any further forward resulted in rough running)
Fuel used over 10min 7 Gall
Fuel Flow 0.7 gall min

Conclusion Moving Mixture lever forward is Leaning mixture.
Mixture lever not 2 Position but incremental (WRONG)
Boost Cut Out req mixture lever forward of 3/4 to Full forward (WRONG)

Spit IIA
Mixture Lever Full Back
Fuel used over 10 min 9 Gall
Fuel Flow 0.9 Gall min

Mixture Lever forward as far forward as possible to achieve smooth engine operation (about 75% forward ...any further forward resulted in rough running)
Fuel used over 10min 7 Gall
Fuel Flow 0.7 gall min

Conclusion Moving Mixture lever forward is Leaning mixture.
Mixture lever not 2 Position but incremental (WRONG)
Boost Cut Out req mixture lever forward of 1/3 to 1/2 Full forward (WRONG)

Hurricane I ROTOL
Method Fuel Feed Main Tanks. Fuel used Total read from both Left and Right Tanks based on assumption that fuel feed simultaneously from both Left and Right tanks.
Mixture Lever Fully Back
Fuel used over 10 min 10 gall
Fuel Flow 1 gall min

Mixture Lever forward as far as possible to achieve smooth engine operation (about 75% forward .... any further forward resulted in rough running)
Fuel used over 10 min 6 Gall
Fuel Flow 0.6 gall min

Conclusion: Moving Mixture lever forward leans mixture
Mixture lever not 2 position but incremental (WRONG)
Boost Cut Out req Mixture lever Fully back (CORRECT)

Hurricane I ROTOL 100 Octane
Method Fuel Feed Main Tanks. Fuel used Total read from both Left and Right Tanks based on assumption that fuel feed simultaneously from both Left and Right tanks.
Mixture Lever Fully Back
Fuel used over 10 min 10 gall
Fuel Flow 1 gall min

Mixture Lever forward as far as possible to achieve smooth engine operation (about 75% forward .... any further forward resulted in rough running)
Fuel used over 10 min 9 Gall
Fuel Flow 0.9 gall min

Conclusion: Moving Mixture lever forward leans mixture but not as much as in 87 Octane ROTOL Hurricane.
Mixture lever not 2 position but incremental (WRONG)
Boost Cut Out req Mixture lever 3/4 Forward (WRONG)

FIXES REQUIRED
Mixture lever should be two position only not incremental
Full Back = AUTO RICH (automatic altitude compensation in rich schedule no Boost restrictions)
Full Forward= AUTO LEAN (automatic altitude compensation in weak schedule Boost restrictions apply)

2 PITCH TESTING IN COARSE
Slightly different method. Set +2lbs Boost Coarse pitch and accept RPM achieved, all other aspects the same as in CSU tests.

SPIT I DH COARSE
Mixture Lever Full Back achieved RPM 2000
Fuel used over 10 min 6 Gall
Fuel Flow 0.6 Gall min

Mixture Lever full forward achieved RPM 2150
Fuel used over 10min 8 Gall
Fuel Flow 0.8 gall min

Conclusion Moving Mixture lever forward is en riching mixture. (WRONG)
Mixture lever not 2 Position but incremental (WRONG)
Boost Cut Out req mixture Full forward (should be Full Aft if orientation is correct)
Richer Mixture results in increased RPM for a given Boost

Hurricane I DH
Mixture Lever Full Back achieved RPM 2000
Fuel used over 10 min 6 Gall
Fuel Flow 0.6 Gall min

Mixture Lever full forward achieved RPM 2100
Fuel used over 10min 8 Gall
Fuel Flow 0.8 gall min

Conclusion Moving Mixture lever forward is en riching mixture. (WRONG)
Mixture lever not 2 Position but incremental (WRONG)
Boost Cut Out req mixture Full forward (should be Full Aft if orientation is correct)
Richer Mixture results in increased RPM for a given Boost

2 PITCH FIXES REQUIRED
In both Spit and Hurri DH mixture lever orientation is WRONG and needs to be changed
Lever back should be AUTO RICH
Lever forward should be AUTO LEAN
Mixture lever is incremental should be 2 position only

NOTES
AUTO RICH provides automatic altitude compensation on rich schedule without Boost restrictions
AUTO LEAN provides automatic altitude compensation on a Lean schedule with Boost Limitations.

In AUTO LEAN engine Boost limitations should be
Hurricane I, Spitfire I +2.5lbs Boost
Spitfire II +4lbs Boost

EDIT: All RAF fighters tested.

[klem]

Excellent work IvanK, thanks.

One thing, you may actually have almost identical results for the various MerlinIII aircraft because the fuel gauge reads out in whole gallons and, for instance, you may have used 6.45 gallons on one test and 6.5 on another. Result: 6 gallons and 7 gallons.

If you like you could use my Performance mission for the tests, get the zip file from post #1 in:-
http://forum.1cpublishing.eu/showthread.php?p=451712#post451712

It gathers the data in a .csv file including fuel reserve as a 'system' parameter rather than the fuel gauge reading. That is in kgs of fuel and the script converts that to gallons (2 dec places) and litres (1 dec place) in the results data. There are Performance.mis files for various aircraft, you just copy one as Performance.mis, run it and select one of the aircraft already in flight, there are aircraft at every 1000 feet starting at Sea level (well about 100ft) up to 30,000ft. Count them off from the left-hand one (sea level)

phoenix, mixture parameter is only available as a Control setting, i.e. no more use than the graphics/control icon. As IvanK says it should be Auto-Rich or Auto-Lean.

[IvanK]

Yes agreed Klem ref only Whole numbers being used. One reason I went for 10mins to get enough Fuel used to at least show the trend. So the Fuel flow values are not super accurate but enough to determine the relationship between Mixture Lever position and mixture strength.

In addition I started each test when the Mouse tool over value was flashing between 2 values indicating the changeover between the whole whole units.

Your Tool is easily more accurate just didnt have time to get it set up today.

Just got the 2 Pitch Hurricane to go. Once done I will update Post 9.... getting a bit dumb struck testing this :)

Once done all will be sent to Devs.

[David198502]

Just gonna copy and paste my post from the ATAG forum here for those who may find it interesting.

OK, Testing done, my findings are:

DH Hurricane.....mixture is back to front, full rich is all the way forward, lean is all the way back....might be why the DH is a pain to start, get lever all the way forward when u push throttle forward.
Hurricane Rotol...modelled correctly
Hurricane 100oct...modelled correctly

Spitfire MkI....back to front...as per DH Hurricane
Spitfire MkIa...modelled correctly
Spitfire MkIIa...modelled correctly
Spitfire MIa_100oct...modelled correctly

Blenhiem MkIV...couldn't see any change. It flew just fine with the mixture where it should be, all the way back. In-game the mixture throttles are all the way forward at spawn.

Made a semi-dark early morning map and these findings are based on yellow and blue flames from the exhaust. If these are modelled incorrectly then all bets are off.
Not sure if it's absolutely needed but I found running the mixture throttle all the way up and down seemed to have a settling in effect after u takeoff (take that for what it worth, maybe nothing).
Now if this is all correct then it should help us with correct engine management and fewer burnt engines. There are other factors of course like rate of climb (keep at 180mph or above), radiator settings
(I aim for between 35 to 50% depending on what I'm doing aiming to keep engine temp under 110* water temp), prop pitch (the higher u go the coarser u will need to run it...been using 2400 when up at 16 to 19000ft) and throttle adjustment...u don't necessarily need hammer down all the time, proper engine management will require adjusting throttle to where it's needed.
Joining the Allied side means u are gonna need to learn how to fly. If u don't want to learn how to fly then get in a 109 E4 and just enjoy urself

what a bullshit statement...get in a 109E4 and fly on rebka against other 109pilots and then see if you still enjoy yourself if you dont want to learn how to fly.
the rest of your post is informative though!

[Torian]

Well I do apologise that the tongue-in-cheek intent did not come across as intended. I'm just glad that we can now work with the mixture modelling knowing at least which which way it's oriented on the various Brit fighters. I find that the 109s seem to have less FM issues and with fuel injected, auto mixture & prop pitch engines there is less to have to factor in with engine management. I like flying 109s but my heart is with the Spits & just wish the devs would get them right.

[David198502]

+1 for that statement!

[Osprey]

Great work all contributors. Given that we apparently have 1 patch to come alone for COD there is a great concern that this may not be fixed, but it is essential that this, plus the temperature problems, are fixed.

I urge all pilots who seek accuracy to push this directly at B6 and Luthier.

~S~

[klem]

Great work all contributors. Given that we apparently have 1 patch to come alone for COD there is a great concern that this may not be fixed, but it is essential that this, plus the temperature problems, are fixed.

I urge all pilots who seek accuracy to push this directly at B6 and Luthier.

~S~

... and if necessary press for this
http://forum.1cpublishing.eu/showpost.php?p=461056&postcount=91

[IvanK]

Doing the Blenheim and its problematical to say the least. ... might need Klems script.

1. I cannot run smooth operation with Mixture levers back (normal) at any altitudes above 6000ft with +4/COARSE
2. Had to perform tests at 5000ft to be able to achieve smooth Engine operation in both NORMAL (BACK) and LEAN (FWD) positions.
3. Tests inconclusive.

METHOD
Stable Flight CHT 200C, BOOST +4, 5000Ft Coarse Pitch Rads 3 clicks open, CHT Stable at 200 C, QNH 1013

LEVER FORWARD in LEAN POSITION
Achieved RPM 1920, Achieved IAS 210
Fuel Used after 10 mins 12Gall (Total)
Fuel Flow 1.2gpm (Total)

Placed Mixture Lever to REAR (NORMAL) position RPM Reduced to 1820 RPM IAS reduced to 200.

LEVER IN REAR NORMAL POSITION
Achieved RPM 1820, Achieved IAS 200
Fuel Used after 10mins 12 Gall (Total)
Fuel used after 20mins 22 Gall (Total)
Fuel Flow 1.1gpm Total in 20min test .... too close to call.

CONCLUSION
Inconclusive with respect Fuel Flow. Almost the same FF achieved in both mixture lever positions ! Though the 20min test might imply that with the lever back fuel flow is less ... though 1.2gpm v 1.1gpm is too close to call imo.
Given Stable engine operation above 6000ft cannot be achieved in Rear (Normal) position then AUTO function is not operating.
Given at 5000ft selecting Mixture to REAR (Normal) results in reduced RPM and IAS I think it implies that actual Mixture orientation is operating in reverse. Maybe supported by 20min Fuel flow tests as well.

RECOMMENDED FIXES (work in progress)
Mixture control needs to be AUTO RICH or AUTO LEAN in that automatic altitude compensation is provide in both.
Stable operation at all altitudes in NORMAL (AUTO RICH) should be possible without boost restrictions
Stable operation at all altitudes in WEAK (AUTO LEAN) should be possible WITH boost limitations
Boost limits in WEAK (AUTO LEAN) +1.5lbs

[phoenix1963]

IvanK - I think you need carb heat above 5000k ft.
56RAF_phoenix

[klem]

Doing the Blenheim and its problematical to say the least. ... might need Klems script.........................

It's here
http://forum.1cpublishing.eu/showthread.php?t=33661
in the first post, see the attachment.

I have added decimal places for fuel reserves.

It won't affect your fuel flow tests (I think) but I am probably going to amend it for level speed tests as the charted TAS is currently calculated from the IAS gauge Air Speed which some people are questioning as to its accuracy. I do include internal 'system' parameter Z_TAS in the output but I chart the TAS calculated from IAS.

I am beginning to think the IAS may be ok though as the Z_TAS is fairly close to TAS calculated from IAS (304mph vs 292mph for IAS 250mph or 4%). The modelled atmosphere could easily do that. Part of The confusion comes from the Z_IAS figure which appears to be way off what it should be, e.g. at a IAS of 250mph at 10,000 ft Z_IAS is only 6mph below Z_TAS because the Z_IAS of 132.46 m/s calculates as 298mph. But I need time to look more closely at it. Hopefully 1C will release more info on the C# parameters so we know what we are working with.

[IvanK]

IvanK - I think you need carb heat above 5000k ft.
56RAF_phoenix

I tried it and still get rough running.

[Torian]

Definitely need carb heat above 5000ft and mixture all the way forward (which is wrong). No problems for me when I do this but also run in full coarse pitch. May need to throttle back to 2.5 boost but smooth flight is no problem.

[Torian]

I posted this link over at ATAG but will put it in here. It's worth a careful read but here is a paragraph that I think is very relevent if u haven't got the mixture orientation correct in CloD

http://flighttraining.aopa.org/students/solo/special/mixture.html

"Excessive leaning at cruise power above 75-percent power will invite engine damage from overheated valves and incur the possibility of detonation. The probability of damage from over-leaning decreases rapidly as cruise power is reduced from 75 percent. For example, there is considerably less, if even any, possibility of engine damage from over-lean mixtures at 50-percent power. However, an over-lean mixture can foul spark plugs and combustion chambers because of cylinder misfiring.

Many older engines are equipped with non-alloy steel exhaust valves. During normal cruise power (approximately 50 percent to 75 percent) the exhaust valve will become glowing hot during the period that it is open and exposed to the hot gases leaving the cylinder. If the mixture is lean enough to create an oxidizing atmosphere, the exhaust valves usually will be damaged. (An oxidizing atmosphere is always present in lean mixtures.)"

This may be why u are getting rough performance Ivank if your mix levers are all the way back and u are using more than 75% power and/or climbing.

[IvanK]

I see where you are coming from Torian but given these things were meant to be AUTO RICH and AUTO LEAN with documented Boost limits for the AUTO LEAN setting rough running (assuming limits are observed) should not be an issue.

[Torian]

Agreed but "meant to be" and what what we have been lumbered with in CloD are very different. Unfortunately we have to learn to manage the engines in this sim in ways that weren't necessary in real life.
And in the case of Brit fighters, with less performance than they actually had.