Performance Calculations (Takeoff, Landing) in SD

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Performance Calculations (Takeoff, Landing) in SD

Performance Calculations (Takeoff, Landing) in SD

Author	Message
pilot-byom	p pilot-byom posted 6/17/2021 6:40:11 AM Post Details Share Post
p Group: Forum Members Posts: 323, Visits: 388	+x 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. 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.
	Reply Like 3
Martin Bech	Martin Bech posted 6/16/2021 6:53:18 PM Post Details Share Post
Group: Forum Members Posts: 152, Visits: 352	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.
	Reply Like 3
Adam Erchegyi	Adam Erchegyi posted 6/16/2021 6:01:58 PM Post Details Share Post
Group: Forum Members Posts: 96, Visits: 2.3K	+x 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? 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.
	Reply Like 3
Tim Dawson	Tim Dawson posted 6/16/2021 1:31:16 PM Post Details Share Post
Group: Forum Members Posts: 8.1K, Visits: 9.2K	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?
	Reply Like 4
Adam Erchegyi	Adam Erchegyi posted 6/16/2021 12:37:11 PM Post Details Share Post
Group: Forum Members Posts: 96, Visits: 2.3K	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.
	Reply Like 8
pilot-byom	p pilot-byom posted 3/8/2021 9:15:58 AM Post Details Share Post
p Group: Forum Members Posts: 323, Visits: 388	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.
	Reply Like 6
PaulSS	P PaulSS posted 3/8/2021 8:57:07 AM Post Details Share Post
P Group: Forum Members Posts: 89, Visits: 3.2K	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.
	Reply Like 6
grahamb	grahamb posted 3/7/2021 6:25:36 PM Post Details Share Post
Group: Forum Members Posts: 576, Visits: 27K	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.
	Reply Like 6
jbmoens	j jbmoens posted 3/7/2021 5:47:20 PM Post Details Share Post
j Group: Forum Members Posts: 17, Visits: 27	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 Edited 3/7/2021 6:12:49 PM by jbmoens
	Reply Like 6
jaimebeneyto	j jaimebeneyto posted 3/1/2021 2:21:42 PM Post Details Share Post
j Group: Forum Members Posts: 9, Visits: 53	Seconded!
	Reply Like 6