Option for Fuel Readouts in Learjet 45

  • Would it be possible to have the option of Fuel Readouts in the Learjet 45 in POUNDS rather than Kilograms? I realize the current limitations of the fuel system, but, still it looks odd to me ever time I scan the panel. It kinda makes me think I feel asleep and used a bunch of fuel, then I have to do the x 2.2 to get a number that my brain understands. Just a small thing, but, would be super nice to have this option. Even it I have to make a text change in the file it would be worth it to me.

  • Jan,

    I seldom fly any of the other planes you referenced. I do fly the B737-500 occasionally though. I know the Commercial scheduled airliners that fly around the world have settings for English vs Metric for crew choices. All my Learjet 45 manuals and data has fuel in Pounds for the indicators and only the text data has Kilograms in ( kg ) for those that read and think in metric.

    Actually, what I am seeking is standard for the Learjet 45. What you have is non-standard for regional or local use. I don't know how that is handled in the real world, but they leave the factory reading fuel in pounds unless something non-standard is requested for home countries that desire something other than factory standard.

    I was hoping for something fairly straight forward. Maybe some file text adjustment with some logic built in. 8o

    This seems to be the only non-standard readout on the panel.

    This got me wondering if this German registered Learjet 45 has altimeters in Meters?


    The bug-a-boo of having to constantly convert fuel quantiles and burn rates from kilograms to pounds or pounds/hr is that none of the charts and graphs use Kg. None, zero, nada. Of course, I know you are going to say this a simulator that nothing is real, but, the whole idea of flight planning and performance monitoring for flying in the sim is to use some semblance of reality and realism.

    I actually have custom charts and tables that I have adjusted and calculated based the best guess at the takeoff weight of this IPACS Learjet. When we didn't have any fuel readouts, it was sorely missed, but when we did get the upgraded panels details with fuel, it was even harder than not having it due to the choice of metric weight for fuel.

    Runway takeoff distance is in feet, not meters, V1, V2, Vr is in Knots not meters/second or some other metric number, Altitudes are in Feet, not meters, Baro settings are about the only thing that is a push button choice of hPa or InHg. The logic is just not present here.

    We try to use realistic airspeeds, climb rates and profiles, proper heading and altitude assignments, distance and time charts, etc. One key performance check is fuel management: fuel burn for climb to altitude, fuel burn/rate /first hour, fuel burn/rate second hours, fuel remaining. All this type thinking requires constantly converting kg to pounds before and during every flight.

    I was just hoping for some sort of adjustment for folks like me that try to fly with some realism added. I know this doesn't really matter for your design criteria for a 6 year old, but do they really know how to fly a Learjet? But, we do a few, damn few probably, real world rated pilots that enjoy the sim.

  • Welcome to the world of aviation where everyone thinks their units are best and only the unit of time seems to be a commonly agreed thing.
    Don't worry, once we add more advanced options for fuel or weight and balance you will probably get the option to switch to your preferred unit system.

    As long as your fuel burn and your fuel amount is measure with respect to the same units you should have no issue of having a feel for when it's about to run dry since the fuel quantity divided by the fuel burn always yields time in the same unit. In pounds it just uses 2.2x as much fuel looking at each number.

    If you asked a physicist they would probably change everything to kg and meter/second in an instant. And most airlines in Europe use kg exclusively, runway lengths are indeed measured in meters over here and probably almost everywhere outside the US and more and more airlines in the US are also changing over to the international standard unit of mass, which is the kilogram.

    Since nowadays both the foot and the pound are defined by their SI-unit counter parts these units are mere factors that are there to confuse us :)

    We're using SI units in Aerofly because we never want to worry about units during our calculations.

    Why don't you ask the manufacturer and they couldn't stick to the international standard... he he :)

    I guess we're stuck with altitudes in feet and speed in knots, because of the nice separation of 1000ft (305m) between aircraft, nice 250kt/10000ft speed limit (instead of 128m/s, 3048m). China and Russia are indeed using metric altitudes already.

  • Thanks for your thoughts, Jan, but, meanwhile is there a way for a user to change the Fuel readouts in the Learjet 45 to pounds instead of kilograms?

    I am way too old to ever see the day when the US changes to metric. It would have been a good idea at the end of WWII, but, it is just too expensive and mostly confusing to those that didn't grow up with it. Waving the flag and carrying on useless conversations are not on my radar. I am just trying to get my favorite sim plane cleaned up and flying right.

    Most of our smaller packaged drinks have switched to metric and practically no one even noticed. But, we still buy our meat by the pound and express distance in miles and everyone has a conversion rate to the dollar.

    How about removing the D-CSDD on the panel, or is that fixed forever? =O

  • Yes and no Ray.. Without access to the original texture maps there is no way to change the background so it will always read KGS though the numbers can be made to show lbs. It would be even more confusing for you than it is now so pretty useless.

    I do hope Master Obi Jan forgives his Padawan for experimenting but I couldn't resist the challenge, sorry Master :rolleyes:


  • I changed the actual numbers to read pounds but Jan’s logic does not use the large center tank. I don’t know if the fuel burn logic uses kg or just elapsed time or actually uses altitude, temperature and thrust settings. Jan Just said is was somewhat realistic.

    I have a test flight in progress to fly to bingo. I am recording time and distance to toc, cruise speed and altitude, etc. I can check some general FF numbers to see if it is realistic.

    Just convincing myself that KGS really means LBS is a lot easier than converting kg to pounds every few minutes or keeping up with a conversion table. This is really no different from having the wrong aircraft ID on the panel and talking to ATC with a different ID.

  • Larry, I just noticed the FF is changing and is KPH so there will be a need to adjust that formula. I can live with the equivalent of wing tanks only, especially when I can overfill them. I seldom fly so far that I need more than about 60 of total capacity fuel anyway.

    Obviously, the smart thing to do for now is the adjust my performance charts and tables to KGS and KPH FF and use the Panel as designed. Thanks for looking and advising.

    Yep, that works out ok for now. Kinda confusing when I fly other planes though. Here is a chart that I updated during a flight from KORD to KGPT tonight.

    Jan, what are the chances of you increasing the base Fuel Quantities in the Learjet 45 to something like 70% or so? You have ~ 44% now with both wing tanks full but the main fuselage tank empty. This makes for mostly short flights. I would like to fly at least 1,000 nm with some reserve.

    I have performance charts for a GW of 15,500 lbs.


  • Again, when the time for the full fuel simulation comes including reducing the mass of the tanks then there will be options to change the fuel on board.

    My current implementation of the fuel system actively vents fuel overboard when the fuel tank is full which is not ideal, I can check if that is an easy fix. Then I could increase the fuel capacity but right now we got much bigger things on the agenda.

  • right now we got much bigger things on the agenda

    Wouldn't we all like to know more about those bigger things... ;)

    As it is now the fuel number is just a thing for fun afaik because even if you run out of fuel nothing happens (unless I missed something...?). I still get a fuel warning in the Q400 after a few minutes of flying while there is enough fuel in the tanks. Seeing the numbers go down is nice and fun but sometimes I wonder if it hadn't been better to not implement such a basic fuel system: it only confuses people.

  • My Lynx will run out of fuel and yes the engines do stop, so it can be done.

    To be fair to IPACS, it's not an easy thing to just update everything as it does take a lot of time whilst adding new features elsewhere., They are a small team and are working flat out so we all have to be patient


  • We can add that engines go out after the fuel runs out but after about a day we'll get the first requests for "infinit fuel". So unless we can offer that option we don't want to force all users to keep track of their fuel, especially since you cannot yet adjust the fuel that you start with. But once this is added the engines will probably spool down when your fuel runs out.

  • We're all for realism which is why we want to improve on the fuel system. But there are more people than you might think that prefer to fly around in a carefree manner, e.g. full afterburner f18 to the moon and back.

    Even I use the infinit fuel option in other simulators, e.g. when I do landing practices. Sure it's fun to fly a go around in a heavy with only 200 kgs of fuel left... see how far you get. But after crashing a few times and having to restart the others simulator which sometimes takes more than 5 minutes... that is a bit too much penalty for my taste and so I set airplanes to un-damageable and having infinite fuel :)

  • I can't even follow that logic, but, I do understand that you can't please everyone or do everything everyone asks with a small team. So I am going to get my morning coffee and daydream about having a fuel system someday. 8o

  • Even I use the infinit fuel option in other simulators

    Do they actually have that option? FSX/P3D doesn't afaik: in those sims however you can easily 'refuel' during a flight using the menu. That might be a better option than only an option for limited or unlimited fuel because it will learn people to mind their fuel, even if they want to go to the moon and back. ;)