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Adam Erchegyi
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+xI must not be understanding something quite right. How exactly would the community look after this data? What is the form of the data you're envisaging? Well, how other apps do it?  The point is to find an uniformized format to code the performance tables from the AFMs, isn't it? The question is just that who maintains the data afterwards.
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Martin Bech
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Can anyone give me the math for the takeoff and landing tables in the POH? Just take it for Cessna 172. I called Cessna and they could not help - use POH. If you then install something in the aircraft you should have new tables. Here Cessna said - contact you service provider who made the change. Well they do not know how to change the values. So please - who have got the math.
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pilot-byom
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+xCan anyone give me the math for the takeoff and landing tables in the POH? Just take it for Cessna 172. I called Cessna and they could not help - use POH. If you then install something in the aircraft you should have new tables. Here Cessna said - contact you service provider who made the change. Well they do not know how to change the values. So please - who have got the math.
The 'math' you want does not exist. Use your brain!
POH and Owner's manual values are empirical statistical values deducted from real world experiments. 'The math' is multi-parameter linear extrapolation and you should already know how to do that. Doing these 'calculations' is intuition, qualified guesses and experience - better call it guesstimates.
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Tim Dawson
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I suspect the way other apps do it is by roughly digitising the graphs from POH books, which are compiled in the manner pilot-byom states. It's unclear where liabilities fall if anyone depends on this digital data.
At present incorporating and maintaining this data is not part of the plans for SkyDemon.
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Daniël Klijnsma
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Reading through this thread, I am not sure why one would want Performance Calculations in SD. You cannot throw away your POH or AFM anyways. These are the binding documents to use when you operate an aircraft. SD or other apps are there only to support you on your flights. But they do not supersede the documentation that comes with the plane, right? And if you don't know the TO / LD performance of the plane you are flying, it is high time to open u these documents before the next flight.
In the end it all seems to boil down to responsibility / insurance if something would go wrong during TO/LD. And this is simple: the PIC is responsible for any flight maneuvers, also for TO/LD. If your engine does not get the proper revs at TO you abort. And if your brakes fail on LD, no calculation will help you anyways. Come on boys and girls, we still fly in real life, not in a simulator game!
Daniël
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BJS
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+xReading through this thread, I am not sure why one would want Performance Calculations in SD. You cannot throw away your POH or AFM anyways. These are the binding documents to use when you operate an aircraft. SD or other apps are there only to support you on your flights. But they do not supersede the documentation that comes with the plane, right? And if you don't know the TO / LD performance of the plane you are flying, it is high time to open u these documents before the next flight.
In the end it all seems to boil down to responsibility / insurance if something would go wrong during TO/LD. And this is simple: the PIC is responsible for any flight maneuvers, also for TO/LD. If your engine does not get the proper revs at TO you abort. And if your brakes fail on LD, no calculation will help you anyways. Come on boys and girls, we still fly in real life, not in a simulator game!
Daniël Yes, but the trend goes to fully nanny brain dead systems. Just look where it brought us in cars, where they started to collect all that data and derived a 'safety system', which in my experience applies a double dumb ass factor for the stupidest driver - not the 'typical pilot' stated in usual POH -, making many systems virtually unusable (or better to say: if nature would work that way, we never would have had anything like evolution). Same effect we have, in part had, in aviation -> many modern safety systems are made more for push button pressing monkeys, and such you can automate later as nobody with biological brain would act like that ;-).
One thing we learned from the latest pandemic is the leaning towards full cover insured life = no risk, no responsibility not to talk into accountability, always technology to blame nor people neither never myself, depersonalization of anything threatening the rainbow illusional world of modern thinking.
T(O and LD calculations are one last resort where brain action is required and I am happy for it.
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moefly
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+xI suspect the way other apps do it is by roughly digitising the graphs from POH books, which are compiled in the manner pilot-byom states. It's unclear where liabilities fall if anyone depends on this digital data.
At present incorporating and maintaining this data is not part of the plans for SkyDemon. As I just stumbled over this thread: I personally find Take Off Distance the most crucial one. The german aviation agency (LBA - Luftfahrtbundesamt) published a guideline (as part of fsm 3/75) that I (and many other pilots I know in GA in Germany) use for that purpose on shorter airfields. The only plane specific parameters it takes is the Take off distance over 15m that you'll usually find in POH. From there it just adds surpluses (which are definitely on the conservative aka safe side) based on density altitude, temperature and runway conditions. To make calcs easier and quicker for me I created an excel sheet where I just put in the base numbers and select the conditions. Maybe that LBA approach would be a simple (as in only requiring one simple airplane specific datapoint - TOD over 15m), yet good solution that could be implemented in Skydemon? Yes, it won't be accurate to the meter, but that's not the intend either. LBA intended it to give a minimum length that it safe to take off based on the conditions. Source: AOPA Germany (I found it to be the most nicely formated one, still based on the LBA fsm 3/75 recommendations), Page 2: https://aopa.de/wp-content/uploads/49_Berechnungen_und_Formeln_fuer_Piloten.pdfUnfortunately I could only find this in German but would be more than happy to translate if copy&pasting from the pdf doesn't work well. And ofc I'm also happy to share my Excel calculation sheet if it's helpful.
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Tim Dawson
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That looks interesting. Are you coming to Aero at Friedrichshafen next year? Maybe you could talk to us about it then?
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moefly
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+xThat looks interesting. Are you coming to Aero at Friedrichshafen next year? Maybe you could talk to us about it then? Not sure yet, but would definitely love to say hello
In the meantime: I translated the mentioned excel calculation sheet to english and attached it here so you can have a look yourself and play around with some test figures a bit.
And who knows, maybe even the sheet itself is helpful to some folks here in the forum (everyone: feel free to use / share / update as you see fit).
Just a quick howto:
It's basically a copy of the original LBA recommendation form. Work through from top to bottom, only change the yellow cells. column E will show the respective Takeoff Distance.
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Tim Dawson
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That definitely seems like a good simple calculator. I will be interested to see what others think.
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