Mixture: All Brit fighters tested

[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]

Originally Posted by klem

...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/showthr...227#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/showthr...712#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.