|Re: Aviation Programs|
Message #6 Posted by Maximilian Hohmann on 18 Aug 2007, 6:00 a.m.,
in response to message #5 by Vincze
I thought Sporty's E6B had that built in? I don't have mine here so I can not check. That easy calculation in states with standard airplane fuel. 6lbs per gallon. (or about 6.7lbs for jet fuel I believe.)
The E6B has a quite arbitrary marking at 0,77 kg/l that is neither correct for AVGAS (0,72 kg/l) nor for JetA1/Kersosene (between 0,75 and 0,84 kg/l). The most popular aviation slide rule in our part of the world, the Aristo (now Pooleys) Aviat has two dedicated subscales for the whole range of densities encountered with different fuel and oil types, both in kilograms and in pounds (see this foto here that I found through google (I would show you a photo of my own Aviat, but I have no idea where I have it, last time I used it must be over ten years ago) http://personal.telefonica.terra.es/web/jcvilchesp/reglas/imagenes/139_aristo_617_a.jpg ).
Anyway, the real-life task is not just a simple conversion, but a little bit more complicated and error-prone:
After landing, we are usually met by the refueller, who wants to know how much fuel we need to uplift. And in a hurry, because there are other customers waiting for him... To compute the required amount in the unit he uses, usually litres, rarely imperial gallons, we need to start from the fuel remaining on board (displayed either in pounds, gallons, litres or kilograms, depending on the aeroplane), the expected flying time to the next destination, an average fuel consumption (again in lbs/hr, gals/hr, l/hr or kg/hr, sometimes not even in the same units that are shown on the fuel gages!) and the fuel type (Avgas or Jet, at 0,72 kg/l or around 0,8 kg/l). Many of these inputs are constants for a certain aeroplane, so it would be an unnecessary complication to re-enter them every time.
Real-life tasks like the one described above really require a calculator with a multi-line display and a menu-system, because they have to be programmed in a fool- and error-proof way that allows for real quick data entry. Also one must be able to see at a glance, if _all_ his inputs are correct (especially the units!). Therefore, tasks like these are now ususally performed with notebook computers or tablet PCs running dedicated software. I once programmed this into my hp-71B, but found that it is not user-friendly and safe enough for the job. It might be different for a private pilot who flies once per week and can spend the rest of the week playing around with his toys, but in commercial operations with multi-sector flights and quick turnaround times, programmable calculators really have become a thing of the past just like everywhere else, I'm afraid.