


Discussion
How to Calculate a set up for F5J and FXJ (heihgt limited)
Hello Everybody
I hope this is the right forum for this question. I had been flying electrics for quiet a while and I had been looking for a category that fit my interest (and budget). I was very ineterested on F5B but the costs are a limiting factor for me, at the moment I just cannot afford it. Just by coincidence I came across with the F5J (http://f5j.eu/rules.php) and FXJ (http://www.rivamodels.sk/FXJthread/FXJ09_5.html) categories and they inmediately caugth me. I was cheking the rules and the outrunner category proposes: Outrunner ◦ outrunner with 28x26mm outside dimensions, 22x9mm stator dimensions, direct drive, unmodified (must conform to factory spec) (http://www.hobbycity.com/hobbyking/s...idProduct=5655) ◦ power source 2x LiPO ◦ smallest propeller diameter is 250mm (10") ◦ minimum model weight 500g As you can see the motors and set up are in general afforbale, but I would like to know how to calculate the best setup for this category, In general it is requiered to have the plane as high as possible in max 60sec or 30sec in FXJ. And I wanted to know if there is a way to calculate if a certain setup will take the plane to the optimal height?? in roder to check different possibilities. and how to calculate this setups in general, thanks in advance for your help and input. EZ 






EZ,
1.52.3 m, 500650 grams, rate of climb 812 m/s, maybe more. You may see http://lmk.polanka.cz/imagegallerie...delyrcek2009 for last year's models, also see http://f5jfun.com/e107/news.php (perhaps use the googletranslate button in top right corner) for pictures from the events. Please note that F5J Euro is a variable motor run variety, so it is up to the pilot to decide when to switch off. The motor (single) run time is then deducted from the flight time. Hope this helps. Jan 





Dear Jan
thanks for the input, I am new on this category so I am trying to learn and understand what it is all about, it is fun everyday I found something interesting. I never thought that such small motors running on 2s bateries could bring up a big 2m plane. I will start soon building my BOLERO, was shipped today and I can barley wait to have it . EZ hooked up with F5J and FXJ 





Ok I found the solution, well partially, using motocalc I can get a pretty good prediction of the performance of the setup. But still I woudl like to find a way to calcualte if a given set up will bring the plane to the desire altitude (e.g 200meters) on the time provided (30 secs). Any ideas???
EZ 





EZ,
Congratulations on the BOLERO, it is a great model. Doesn't Motocalc return also the estimated climb rate? For estimating a climb rate I use a following "thumb rule" formula: climb rate [m/s] = input power [W] / model weight [kg] / 10 * efficiency This efficiency is usually around 0.35, for heavily overloaded motors could drop to 25%, for geared motors could reach 50%. For the SOR drives defined above you may take 0.28 as a reasonable first estimate. Jan 





EZ, this thread should help:
https://www.rcgroups.com/forums/show....php?t=1150155 Neil. Quote:







You have to select that column in the Options dialog.
Neil. 








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