aircraft.cfg - FDE - Prop/Engine question

[badderjet 181]

Hey all,well I am just wondering if the following is possible, but I am getting just crazy results so I'd need your advice:The max. engine RPM should be at 7500 while tha max. prop RPM just about 2600. I set the engine data in the max_rated_rpm and now wanted to get the gear_reduction_ratio in the propeller section working. How can I achieve the prop turning at 2600 when at full throttle?Not too bad if it doesn't work, just curious... ;-) Thanks in advance,Etienne :-wave

[Guest jlwoodward]

The ratio is either 2600/7500 or 7500/2600, I'm not sure what convention is being used. You will also need to select the constant speed prop. If you are using a fixed pitch prop you will have to fool with the blade angle to control the max rpm. Put the parking brake on (ctrl-.) and give it full throttle.John Woodward

[Guest Milton]

For the aircraft.cfg, specify gear reduction as 2.884.For beta_min and beta_max, use realistic numbers if you have them. Otherwise start with 15 min and 45 max. Usually prop tables start at 15 so any reduction below that will affect takeoff roll distances or require that you pull the prop back to increase pitch.The wise thing to do IMO is to head over to http://www.mudpond.us/ and download Jerry Beckwith's excellent spreadsheet to generate an .air and .cfg file specific to your aircraft. The results are amazing. Get the noted test panel as well.Good luck and have fun :-)Milton

[badderjet 181]

>For beta_min and beta_max, use realistic numbers if you have >them. Otherwise start with 15 min and 45 max. Usually prop >tables start at 15 so any reduction below that will affect >takeoff roll distances or require that you pull the prop >back to increase pitch. Unfortunately I don't have the exact numbers, but I'll try. Yes it's a constant speed prop.>>The wise thing to do IMO is to head over to >http://www.mudpond.us/ and download Jerry Beckwith's >excellent spreadsheet to generate an .air and .cfg file >specific to your aircraft. The results are amazing. Get >the noted test panel as well. Thanks for the link!!>Good luck and have fun :-) Thank you, also John! :-hahGotta try out as soon as I'm back home today.Etienne :-wave