Fuel flow and magnetic variance

[jimskifs]

Two questions.

Is it possible to alter fuel flow say through a scalar in the "aircraft" file? Some airplanes are way off as far as endurance is concerned.

How does cfs2 figure magnetic variance? The program applies it all the time as you fly but I see no tables or such. You can't plot a long flight in a real way without knowing this.

Jimski

[jimskifs]

Well, I take it the fuel flow change can't be done. I will continue to fly with "unlimited fuel".

On the magnetic variation issue I googled around a bit with an fs9 search. Apparently the info is stored somehow in the /scenery/magdec.blg file and no one knows how to read it. There seems to be an agreement that the file is the same in all MS flight sims from the oldest to the newest and that the best fit to the data is by using mag variance tables from 1988 or 1990. Scenery designers fret over it because they need new runways to line up properly. It looks like the usual routine is to make a quick trial runway (always done in true heading by the design programs) and then take a test flight being careful to read the magnetic compass as the plane sits on the runway, the difference in true runway heading and the mag compass reading is the magnetic variance at that location.

Jimski

[bearcat241]

For optimum ranges, learn to use altitude and mixture---as altitude increases, air density decreases and so does parasite drag. The best fuel economy is obtained above 15,000 ft for most prop a/c -- jets even higher.

Mixture control is the second factor: leaner settings at higher altitudes extend range.
http://www.dauntless-soft.com/PRODUCTS/Freebies/Library/books/FLT/Chapter4/Mixture.htm

[Jagdflieger]

Jim,

The magnetic deviation is well modeled in CFS 2, but I don't think that it is the variation that was present in WW II. As you know, it shifts as the magnetic pole moves around. As the magnetic pole is not currently adjacent to the north pole, the declination vairies with latitude and longetude.

Here are a few diagrams that might help you navigate to within a few miles of where you want to go.

[Tango_Romeo]

Two questions.

Is it possible to alter fuel flow say through a scalar in the "aircraft" file? Some airplanes are way off as far as endurance is concerned.

How does cfs2 figure magnetic variance? The program applies it all the time as you fly but I see no tables or such. You can't plot a long flight in a real way without knowing this.

Jimski

...by settings in the AIR file. And, yes, you can change them using AirEd. No sense in trying to use a CFG entry.

'Fuel Flow' is controlled by the throttle. Max and minimum values for this are set in the AIR file as well. :ernae:

Note: Using Scalars to control settings is not the best idea in the bag, as these values do not effect both player and AIs equally.

[jimskifs]

First the mag variation. Thanks much for the charts. I have been using the same one for Europe for the past few years with success. Mine has no date on it but I see the US chart is dated 1990 which agrees well with what the fs9 people are saying. I am pretty sure this is the best we can do.

As for the fuel consumptions, the two planes I take issue with are the Malinowski B24J and the 1US_B17E. Both seem to run out of fuel long before they should. It is possible I am feeding from just one tank and my panel isn't letting me switch tanks. I may experiment with Aired by putting all the fuel in a center tank and see if I get full range.

As far as mixture goes, neither will climb well above 5000' unless the mixtures are well back. I think I am setting the mixtures at about 65% at altitude with good performance, the engines will quit below that.

Also I saw no adjustment in the Aired program for either plane's fuel consumption, although it might be hidden as one of many "unknown"s. I did not see a throttle min/max setting either. Luckily the range of both planes is well documented and is longer than my attention span.

Jimski

[Tango_Romeo]

First the mag variation. Thanks much for the charts. I have been using the same one for Europe for the past few years with success. Mine has no date on it but I see the US chart is dated 1990 which agrees well with what the fs9 people are saying. I am pretty sure this is the best we can do.

As for the fuel consumptions, the two planes I take issue with are the Malinowski B24J and the 1US_B17E. Both seem to run out of fuel long before they should. It is possible I am feeding from just one tank and my panel isn't letting me switch tanks. I may experiment with Aired by putting all the fuel in a center tank and see if I get full range.

As far as mixture goes, neither will climb well above 5000' unless the mixtures are well back. I think I am setting the mixtures at about 65% at altitude with good performance, the engines will quit below that.

Also I saw no adjustment in the Aired program for either plane's fuel consumption, although it might be hidden as one of many "unknown"s. I did not see a throttle min/max setting either. Luckily the range of both planes is well documented and is longer than my attention span.

Jimski

...the aircraft you are using, BUT:

- If you simply add a fuel selector switch to your panel, you will know which tank you're running on, and can switch as needed. I believe you will find that the selector switch must be enabled in the AIR file as well....but that is an obivious setting in the tank section.

- I do not know which ENGINE your aircraft have specified in the AIR file. It could be the FS98 Engine or the FS2000 Engine. They are quite different. And, unfortunately, not all AIR files of either type have exactly the same entries. It depends on who wrote/modified the file.

At the very least, you will find a Throttle Effectiveness table (a graph), which can be modified by exporting the graph to MS Excel and redrawing it.

Also, you will at least find (if not a fuel consumption entry in Gal/hr), two other settings that will decrease fuel consumption in the Prop Efficiency and Fuel Pressure settings. These two should be present in all AIR files.

Hope that helps. If not, send me the AIR files and tell me by what percentage you want the range increased on internal tanks.:ernae:

[jimskifs]

Both the planes mentioned have several tanks and I see no way of selecting tanks with the given panels. When I run AirEd on them about half of the entries read as "unknown". I see no way to enable a selector switch. I am new to AirEd.

I did use AirEd to transfer all the fuel to one tank in each ac and got reasonable results and I feel that is where the main problem lies with these. The B24J looks to have about 14 hours endurance now with full fuel and the B17E about 8 hours. I think both are believable and that the B17 probably would have aux tanks for a long ferry flight. William Green's Famous Bombers Of The Second World War says the B24j would have 7.3 hours endurance with 5000# bomb load and 2400 US gal fuel at 25000' at 233mph. (The sim model had no bombs and 3400 gals.) That is pretty specific and I should be able to test for it. The B17G in the same book rates at 8.7 hours endurance at 213mph at 25000' with 4000# bombs with 2800 US gallons. The sim model only has 1700 gallons. So I have well defined points to aim at.

Let me fiddle with it a bit more. I'm learning a lot.

Thanks for the help.

Jimksi

[bearcat241]

You can't enable a selector switch in AirEd. Its already enabled by defo in the sim engine for every plane with multiple tanks. You access this feature by installing a tank selector on your 2D panel in the panel.cfg. Programs to use are CFGEdit or FS Panel Studio.

[Tango_Romeo]

1. You would have to be proficient with PanelCFG or CFGedit to add a Tank Selector gauge to your panel, or you can change the panel to one that has a selector already installed.....which is only a matter of switching the panels.

2. AIR files are not the simplest things to understand and take some study, but they are not rocket science. However, until they are familiar to you, it's probably best to keep the tinkering to a minimum.

That being said:

- the numbers you have quoted from Green's book are somewhat different from those available through other sources for both aircraft (a very common situation with all aircraft), so consider that perhaps you are putting too much faith in those.

- The AIR files you have for both of your aircraft come from unknown sources, and there is no way of knowing how accurate they are with respect to anything.


SUGGESTION FOR A SIMPLE FIX:

Put all of your fuel in one tank....an accurate amount for both. And use a Scalar in the CFG file to reduce the Drag Coefficient and increase Prop Efficiency in the AIR file enough to get the endurance you feel is correct. :ernae:

[bearcat241]

Get Airwrench from Jerry Beckwith and you got a more scientific tool for adjusting economy, drag and prop efficiency all in one bag, plus a lot more...

[Tango_Romeo]

Get Airwrench from Jerry Beckwith and you got a more scientific tool for adjusting economy, drag and prop efficiency all in one bag, plus a lot more...

... really like AirWrench? I got hooked on Aircraft Airfile Manager (AAM) way back before their site went down. I suppose I should give that a try. AAM was/is a freeware program that I got at DVdata when I bought their Aircraft Container Manager (ACM).

[bearcat241]

Yeah, its pretty cool for knocking out a quick draft of air files for FS8/9/10 and CFS2. But for optimum CFS2 AI usage you have to edit the *.air and the *.cfg afterwards for fine tuning and to clean out all the useless FS stuff that might affect CFS2 AI performance.

[VF15_gray]

Mag. Dec:

The VF15 put in a lot of hours trying to crack the magdec.blg and ended up CFO’ing a PBY on a 5° grid over a large area of the PTO. The raw data was then plotted using a linear regression formula.

The results are here - scroll to the bottom.
http://www.vf15-flyingaces.com/vf15_pto_maps.htm

Sorry for the rough Dec. lines on the map. I could not get PhotoShop to do splines, so they are a lot of short straight lines.

S`

[jimskifs]

Just landed from a 1US B17E flight from Pueblo (Co)AAF to McClellan AAF (Sacramento). I have now a good scenery update for the US and have modeled enough old AAF's in proper locations to fly around the US. This was a 910 mi flight done totally by dead reconning. (But I always simulate perfect weather.)

First, the fuel consumption. The only fuel selector I knew to try was the P38 job. It will select tanks and show the fuel remaining in the tank but really didn't select tanks to burn fuel from. Thus I could select an empty tank and it shows zero on the guage, but the engines continue roaring (unless I select OFF). At least that is how I saw it. So I used AirEd to move all fuel to the main tank, revised the capacity according to Green's book, adding the amount he gives for a typical bomb bay ferry tank. It works great. At 2/3 power and prop settings, mixtures at 50%, it cruises at 200mph (got a bit faster as fuel burned) at 15000' and looks like it will go about 3000 miles with full ferry fuel, which I find totally realistic. Satisfied.

For the mag dec, I used the 1990 data from

http://geomag.nrcan.gc.ca/apps/mdcal_e.php?Year=1990&Month=8&Day=18&Lat=50&Min=&LatSign=1&Long=20&Min2=&LongSign=-1&Submit=Calculate+magnetic+declination&CityIndex=0

You have to type in lat and lon for your way points to get the mag dec at those points. On this flight it varied from 11E at Pueblo to 15E at Sacramento. I used the Rand McNally road atlas to get something like a great circle route, adjusting my heading every hour to allow for changing mag dec and the changes required by the great circle. I hit McClellan dead on. I am usually not so lucky.

Well, next I'm off from McClellan to Hawaii! Thanks for all the help. What a great simulator!

Jimski

[VF15_gray]

Try Moparmike's individual fuel switches.
mape_fuel.zip

http://www.sim-outhouse.com/index.php?loc=downloads&page=downloads&FileType=cfs2-panels&Category=gauge#download

This will allow you full fuel control.

S`