Hi,
I own a 1980 TA IV and I note quite a difference in true airspeed gained vs POH. For example, for FL160, OAT -13C, 75%, leaned 100 RoP the POH states 168 true. But I'm getting only 157 true. That's a difference of 11 knots! Moreover, the plane has the complete Lopresti speed kit installed which should provide another performance gain of 10 knots so actually I'm about 20 knots too slow! Similar differences are on other flight levels/temps. I have a Garmin 500 installed which measures TAS exactly.
Also my climb rate is quite low. With cruise climb speed (104 KIAS, 33/2450) I'm getting 500 fpm at maximum. Sometimes only 400 fpm.
While investigating the reason I figured out that the exhaust was about 10 cm too long (a prev owner added some extra piece to avoid cleaning the belly). I've cut that and brought it back to standard length.
Another point are the lopresti wing tips. They are not in line with the ailerons but have a level difference which is thick as a finger.
I guess fixing this this will give me an improvement of may be 5 knots. But what about the other 15 knots? Prop, governor, mags are fresh overhauled, engine has only 600 hours since last overhaul, gear-up check was ok (see link below), turbo charger is dry and easily reaches 41".
Here are some pics of the wing tips, the exhaust and the gear-up checks: http://www.flickr.com/photos/42723580@N03/sets/72157629056505347/
Any hints where to look further are highly appreciated!
Thanks,
Andreas
I own a 1980 TA IV and I note quite a difference in true airspeed gained vs POH. For example, for FL160, OAT -13C, 75%, leaned 100 RoP the POH states 168 true. But I'm getting only 157 true. That's a difference of 11 knots! Moreover, the plane has the complete Lopresti speed kit installed which should provide another performance gain of 10 knots so actually I'm about 20 knots too slow! Similar differences are on other flight levels/temps. I have a Garmin 500 installed which measures TAS exactly.
Also my climb rate is quite low. With cruise climb speed (104 KIAS, 33/2450) I'm getting 500 fpm at maximum. Sometimes only 400 fpm.
While investigating the reason I figured out that the exhaust was about 10 cm too long (a prev owner added some extra piece to avoid cleaning the belly). I've cut that and brought it back to standard length.
Another point are the lopresti wing tips. They are not in line with the ailerons but have a level difference which is thick as a finger.
I guess fixing this this will give me an improvement of may be 5 knots. But what about the other 15 knots? Prop, governor, mags are fresh overhauled, engine has only 600 hours since last overhaul, gear-up check was ok (see link below), turbo charger is dry and easily reaches 41".
Here are some pics of the wing tips, the exhaust and the gear-up checks: http://www.flickr.com/photos/42723580@N03/sets/72157629056505347/
Any hints where to look further are highly appreciated!
Thanks,
Andreas
