differences in between 1967 and 1974 M20F tables

[podair]

Hi

I ve just come across some power setting tables for a 1974 M20F. So far I have found my 1967 tables to be a tad optimistic , I am getting TAS up to 10mph slower, which in the grand scheme of things is not a big deal for a 42 year old airframe, and perfectly acceptable. I have seen much worse differences on other makes! However I am curious as the 1974 ones are bang on the mark. For example, the typical TAS I get running FT/2500 at 10,000 ft is 146kts (168mph).My manual says I should be getting 179. the 1974 one 168... so spot on.

Apart from the much talked about dirty wing etc , is there any justification for the difference in figures (they are all 8 to 10 mph slower in the mid 70s tables compared to 1967), or was it just a case of the marketing department in the 1960s getting the upper hand. Also, I have a 3 blade prop, so that might cost me a few knots. My wing step does retract, I believe they don't on the 1970s models.

Just curious really. I run at peak EGT/slightly lop with stock injectors, getting consistently 145ktas at 10k ft with 8.5 gal/hr, that's pretty good already!

Patrick

1967 M20F Executive OY-DFD

[Parker_Woodruff]

LOP in my Mooney costs me between 10 and 13 kts.  I haven't really nailed down that figure yet.  All I know is I've seen ROP numbers topping out at 167 on one occasion, but in general between 160 and 163 KTAS.

That said I've only run ROP about 3 times looking for real performance information.

 

LOP I'm getting between 150 and 156 KTAS, but generally around 151-152 KTAS.

 

1990 M20J-AT

[67M20F]

I get around 160-165 MPH, running at 75 ROP at 9500

[Cruiser]

Quote: Parker_Woodruff

LOP in my Mooney costs me between 10 and 13 kts.  I haven't really nailed down that figure yet.  All I know is I've seen ROP numbers topping out at 167 on one occasion, but in general between 160 and 163 KTAS.

That said I've only run ROP about 3 times looking for real performance information.

 

LOP I'm getting between 150 and 156 KTAS, but generally around 151-152 KTAS.

 

1990 M20J-AT

[Parker_Woodruff]

Quote: Cruiser

 Parker,

Need more details on these performance numbers. How rich is ROP........ 50°F? 150°F? How lean is LOP? What MP and RPM settings? 151-152 KTAS LOP is pretty good. At what settings. How about CHT? Over 360°F?

 

thanks,