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Guest Ian_K

AIR-file section 1506, help wanted!

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Hi!Guess there are some of you who know what to do in the following case:I have a Dash8-100 who have some bad speed / drag characteristics. Have tried to alter the drag and thrust sections in aircraft.cfg, but this dont help. Problem is as follows. The dash accellerates a bit too fast, she reaches Vr about 3.5 seconds to early. Climb performance is also a tad to good,. with flaps up, speed set to 150 IAS, trq at 96 % and prop to 1050, she climbs with almost 3000 feet / min. This shold be about 2000.At cruise level, the speed is again to low. She gains only 190-200 IAS at e.g FL080. TRQ set according to POH, and RPM at 900. this speed should be about 205-215.I have heard that a edit of the table in section 1506 of the AIR file should do the trick. Aircraft does fly very well except for this. AoA is good, and she maneuvres as she should.Please, any of you dynamic-gurus ( Ron, do you feel like helping ? :) )hear my prayers here :)Of you like to try out this Aircraft, it exists in the FILES - Aircraft FS2004 section of Http://www.virtualwideroe.com. This is a merge of Fandas dash8-300 and a Project AI model. hope to hear from you soon :)rgdFreddy WilhelmsenNorway

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Hello Freddy,this is from a thread on AvHistory/Decode which should answer your questions. Ask there if still not sure:http://www.avhistory.org/scripts/MegaBBS/t...ageID=5544#5544-----------------------------------------------------------Subject : RE: Increasing top speed?Posted : 24/9/2003 2:49 PMPost #5546 - In reply to #5544 --------------------------------------------------------------------------------Yes. You need to read some aerodynamics books or look up the resources on the web.For small angles RoC = (Thrust-Drag)*Speed/weightMax level speed is when RoC = 0 so increase the max speed and you will always be able to climb at the old max speed. How would you limit the max. RoC only?You have to increase the thrust or thrust minus drag AT the max speed and keep it/them the same at max climb speed (Vy) is ONE way. You can change the piston engine model ( may be a bit) and the propellor model as it is a function of speed. J=V/(nd). J is an index into tables 511 and 512 in the .air files.If you are modelling from real performance data you should be able to get a good match in the sim I would assume to a few %.Are you good at Applied Maths?Ian------------------------

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