By C401 - 2/24/2021 12:50:17 AM
This would be an amazing feature to have and is one of the last things missing that would make Skydemon essentially a one stop shop solution for me.
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By jbmoens - 3/7/2021 5:47:20 PM
I second this as well.
I am currently using a clunky excel sheet to calculate TO and LD distances, and most of the work is about inputing info that I get from SD.
For most aircraft, it can be quite convoluted to implement the feature as each parameter (temperature, pressure, wind speed, etc) has its own set of non-linear response curves. Basically the "profiles" need to be a series of n x m matrices for interpolation. It won't be as easy to define as the current plane profiles. But if excel can do it...
BTW - I am happy to share my excel with SD's developers if that can be helpful
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By grahamb - 3/7/2021 6:25:36 PM
I don't know why people are using the term 'yet'.
Tim D. has said on more than one occasion that he is unwilling to implement such a feature.
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By PaulSS - 3/8/2021 8:57:07 AM
I don't blame him. Far too many types and sub-types to consider and that's before the various factorisation is considered for grass, wet etc etc. Unfortunately, there is also the ugly head of liability which would rear up if an accident occurred due to an incorrect performance calculation.
I would certainly point the pilot to his POH and tell him to work it out himself.
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By pilot-byom - 3/8/2021 9:15:58 AM
The lifetime span of types flying is huge, the methods to generate theses empirical data are legends (god blessed it is real data and no computer video game stuff) and in the end is requires to interpolate real world values out iff the POH or earlier. Programming a generic tool to put in all lists of data and provide a usable interface is far beyond the capabilities and feasibility for a company like the one behind Skydemon.
I know other software tools in totally different environments doing exactly what is proposed here. My experience with these tools is - once they reach a stage of 'good enough', the usage of the software tool is more complicated than simply taking the original paper and do the math yourself.
I second Tim Dawson and the Skydemon crew, the effort is not worth it.
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By jaimebeneyto - 3/1/2021 2:21:42 PM
Seconded!
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By erchegyia - 6/16/2021 12:37:11 PM
I strongly believe most of the people against this feature are considering the perfect solution. From my point of view, it doesn't have to be perfect/legal. It would be great to have some non-binding thumb rule values for information, we are going to apply a personal safety margin and some more due to aircraft age/conditions anyway. As mentioned before SkyDemon has a bunch of environmental/acft data already available and it would be a great benefit not to enter them manually to 3rd party applications (I bet they are not perfect either).It doesn't even have to be an exact number, maybe a confirmation/warning scheme? calculated roll resulted in 400m and you got TORA 2,5km? give a green light! calculated landing distance two times more than the LDA? show a warning! it's on the edge? give a warning and tell the user to make the exact calculation based on the AFM
How nice this could be for the destination finder? You don't have to set a general RWY length filter for all, could simply exclude airports for the current load/weather. I also understand this is a lot of work to do and an incredible amount of data to maintain. It's not an accident that ForeFlight only has it in the most expensive plan only... But you don't need to do it! Just provide the tools in the application(s) and let the community maintain the data.
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By Tim Dawson - 6/16/2021 1:31:16 PM
I 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?
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By erchegyia - 6/16/2021 6:01:58 PM
+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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By Martin Bech - 6/16/2021 6:53:18 PM
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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By pilot-byom - 6/17/2021 6:40:11 AM
+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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By Tim Dawson - 6/17/2021 9:39:34 AM
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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By Cheeseman1112 - 10/6/2021 7:20:58 AM
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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By BJS - 10/8/2021 6:51:16 AM
+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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By Tim Dawson - 9/13/2024 9:16:31 AM
That definitely seems like a good simple calculator. I will be interested to see what others think.
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By Sky Painter - 9/13/2024 10:36:19 AM
+xThat definitely seems like a good simple calculator. I will be interested to see what others think. +1 |
By fabria - 9/13/2024 11:59:33 AM
+xThat definitely seems like a good simple calculator. I will be interested to see what others think. Downloaded the Excel sheet from moefly - very easy and straight forward. Of course it's just for reference, but definitely a help when planning. I like it. |
By thomas.fischer2018 - 11/9/2018 2:18:33 PM
I know it's been discussed before, but I still don't understand why this feature is not implemented yet.
The manual calculation of the takeoff and landing distance is relatively timeconsuming, annoying, and it can be 95% automated as shown by other apps or competition software like Flight Planner. In Germany it is mandatory to do this and document it (at least for insurance reasons it's advisable).
Calculation of the takeoff and landing distance (and perhaps climb performance) depending on - airport elevation - temperature - pressure (or the density altitude) - wind direction & speed at the time of departure or arrival
- weight (from weight & balance calculations) at the time of departure or arrival - runway condition (inclination, grass, and user answered parameters like wet or not, active runway selection) - aircraft profile - user specific safety margin would be a great feature, both for planning in advance as well as during in-flight.
Aircraft performance profiles could be edited and shared by users for the most common aircrafts like Cessna 172 etc. The map could be filtered for airports that have long enough runways, also in case of an emergency to find a field nearby. Or it could show on the warnings tab if the the calculated length is shorter than the landing distance available.
I love SkyDemon, but i would like to get rid of these other apps that i need to calculate those distances for me....
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By moefly - 9/12/2024 6:55:16 AM
+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.
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.pdf
Unfortunately 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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By Tim Dawson - 9/12/2024 9:56:34 AM
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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By moefly - 9/12/2024 11:09:19 AM
+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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