Poor performance needs to be improved.

Every once in a while I download an airplane for a specific reason. Generally that reason would be best served if the aircraft performed close to the way it was supposed to. Recently I had cause to search for and download (the only example I could find) a Piper PA 28 236. As far as I can tell, there is only one available, created by JRLucariny, file name (this site) EMB710C.zip.

 

When I opened the file, I found a rudimentary panel, one without some instruments that this aircraft would require, and no provision for the adjustment of manifold pressure, something an engine of this size would most assuredly have. The author states in the Aircraft file : “Power plant: one 235-hp (175-kW) Avco Lycoming O-540-J3A5D flat six piston engine \Performance: maximum speed 170 mph (274 km\/h) at sea level…” That is the correct engine for the type, however, in the Piston Engine section is the following.

 

power_scalar=1.000

cylinder_displacement= 90.000

compression_ratio= 8.500

number_of_cylinders= 4

max_rated_rpm= 2700.000

max_rated_hp= 180.000

 

The best I could get out of this plane at 1,000 feet, straight and level, calm without wind, was 107. The actual should be 170 mph; cruise should be 155 mph to 165 mph.

 

I found a plane in my hangar with the same engine and substituted the piston engine section of that plane for the faulty one, but the results were unspectacular; it didn’t do much.

 

I love a challenge, but can someone give me a starting point as to how I can get this puppy up to spec?

 

Thanks…

 

KCD

The airfile probably needs editing, you can use AirEd (godaired.zip) by William M. Roth to do this from the library, you could start by editing "table 505" this contains engine specifications.

Thanks, Paul, I'll give that a try.

KCD

 

 

RESULTS of Paul's suggestion...

 

By using AirEd I reolaced the incorrect entries with those proper for the rngine, There was a noticable improvement,but not enough to bring it up to spec. at 1,000 feet, straight and level, calm without wind, I was able to impprove top speed by only about 20 mph to 121 knots. Need more ideas and/or suggestions. This plane and Power plant (235-hp (175-kW) Avco Lycoming O-540-J3A5D flat six) should yield a maximum speed 170 mph (274 km\/h) at sea level under the conditions I'm using to test it.

The airfile probably needs editing, you can use AirEd (godaired.zip) by William M. Roth to do this from the library, you could start by editing "table 505" this contains engine specifications.

 

Experiment with the power_scalar=1.000 factor in the aircraft.cfg file as a start. likely way to low for the lift/drag profile. Start at about 1.5, work up or down from there.

Just a note: watch out for knots vs. miles per hour. Your 121 knots is a touch over 139 mph. Don't know how your ASI is calibrated.

If the takeoff performance is currently correct but the cruise speed is too slow, you may want to play with the parasite and induced drag scalars in the Flight Tuning section (if it doesn't have one, you can add it from another plane). One affects all speeds, and the other only high speeds.