Simbrief takeoff performance
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Hello everyone,
what is your experience with the Simbrief takeoff performance calculator and the RJ?:
https://dispatch.simbrief.com/toolsI recently tried a takeoff from LIMJ from intersection G with derated thrust and the result was extremely close to disaster. These were my values:
The V-speeds are pretty close to the values from the clipboard, so they seem to be right. I first calculated the takeoff with the actual temperature (13°C) and Simbrief gave 50°C as maximum temperature. Then I calculated the takeoff again with 50°C. Is this method a valid way to get a derated thrust value?
If so, what could be the reason why the takeoff did not work out? The acceleration felt extremely slow, is the JF RJ not accelerating fast enough at this thrust level or are the Simbrief values not as reliable as I was hoping? -
I don't believe this is a valid method of determining assumed temperature for takeoff. There is another post here, a little further down in the forum which talks about use of reduced thrust and assumed temperate determination.
https://community.justflight.com/topic/7463/wuestion-on-redu-toga
There is a spreadsheet available that works very well. It's been rare for me to get an assumed temp over around 35 degrees.
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What I see on that calculation is that your take-off weight is equal to your max take-off weight.
I would not take-off with weight margins that low.
In your case, I would've used the standard reduced thrust instead just to get better margins in terms of weight. By standard reduced thrust, I refer to the temperature setting that is automatically set when you push the REDU button on the TRP.
Yes, the numbers say you can do it but you also need to think about whether you should or actually can do it.
That thought process would be there IRL as well, so that in itself it's not just a sim adaptation.Let's say it would've said that the max take-off weight for 50C was above 40-41 tons, then I would've felt more comfortable with it.
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@smashingjonor You mention the TOW. I just noticed, I did not have the JF variant selected which has a different MTOW. My actual TOW was 40704kg, this yields:
So with the correct variant, the limit is allegedly the MTOW of the RJ70 and there is still a large margin with the weight. The V Speeds are now higher and the stop margin is now 250 meters. Still, my takeoff should have been possible with an assumed temperature of 50°C. 250 meters should have been enough of a margin.
I will keep an eye on this. I think I will need to find the performance tables to verify that the Simbrief values are correct or not, so I can figure out if this is a problem with Simbrief or Just Flight. In any case, I wish the EFB would offer performance calculations...
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As per my original post. You are using the product incorrectly. Simbrief does not offer a REDU assumed temp value in the calculation. (See THRUST SETTING TOGA MAX) in the takeoff solution in your image. You could probably derive one from the max temp, but this feature is not directly provided.
If you want to use assumed temp REDU thrust, use the spreadsheet which I referenced and linked above.
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Hi,
I developed a spreadsheet for the 146, and subsequently modified it for other aircraft including the RJ. The only performance data I have for flex temperatures are for the 502 engines in the 146. So the figures may not be quite correct for the RJ variance with the 507 engines. By adding your figures for weight and weather into the spreadsheet I came up with the highest flex temperature of 32 degrees. I attach a link which would allow you to download the spreadsheet. Be advised you also need to download Libra Office in order to use it. Any comments would be appreciated.https://flightsim.to/file/24722/aircraft-runway-performance-spreadsheet
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Hi there,
I was just wondering where you find your data for the 146.
I am currently doing a university project where I need the performance parameters for the aircraft but I am struggling to find values. I understand you have made a spreadsheet but for the project I would need to take the data from reputable sources.Any help would be appreciated :)
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Hi,
Well unfortunately there is not a lot of performance data available now. I will try to attaché what I have. Just Flight wont permit me to copy files, but here is a link to one set of data.
There are still operators of the 146/RJ, you could try contacting them, I'm sure they would help with a university project.
You could also try contacting BAE Systems.i must admit from the point of view of the Spreadsheet I have been testing the performance calculations against the Just Flight aircraft as that is the only option I have. but I'm pretty confident, based on the historical routes operated that Just Flight have done an excellent job.
If the link doesn't work try searching for "RJ Technical Data at a glance".
chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www.aviation-broker.com/fileadmin/user_upload/jetxchange/flugzeugmodelle/general/RJ_Tech_data_at_a_glance__April_2004.pdfGood Luck