Power Settings and Speed?

[MikeinFL]

Hi guys,

 

I am wondering what type of settings/fuel flow and real world speed you are seeing in your M20F's?

I am thinking I am not running my "optimally" as I usually average around 140 knots or so.....

THANKS!

 

Mike

[podair]

my aircraft is a 1967 M20F with a three blade prop but otherwise completely standard (no mods), still has the original factory paint!

Funny enough I don't get anything near the 1967 POH speeds , but I have a set of 1974 charts which are spot on!

as posted earlier in the main discussion, I tend to fly high, routinely 10k ft, full throttle and peak EGT/slighly lean using an EDM 700. I always get 145kt tas and 32ltrs per hour (8.5gal), normally works out 140-145mph indicated. Higher at 12k I d get 142ish and 30 (7.5). Lower I use the power charts to be around 70%, always 2500, and usually get 140/145mph indicated. At 65% I get around 135mph indicated.

Optimum loafing around settings seem to be 2200rpm/22in at 2000ft (no restrictions with the 3 blade), 50deg lop and get 26ltrs per hour which is around 6.5gals US.

 

[Guest Anonymous]

You did not say which model M20.  I am assuming an F or G model based on the window configuration.

Mine is a '68 G model, but it has a few more mods than yours.  I have the Lake Aero cowling (without cowl flaps), flap, aileron and tail seals and the old style one-piece windshield  (I liked the avionics access).  It also has electric gear, but retains the hydraulic flaps.  This was a common configuration for the '08 models.  Like you, I have a three bladed prop.

I am very happy with its performance.  I normally cruise at between 7000 and 10,000 feet, as the normally aspirated, and carburated G is not a high altitude airplane.  I do have a little portable oxygen setup, but rarely use it.

My "slowest" Mooney model will give me 138 knots at 7000 with 22 inches and 2400, which is not quite WOT, resulting is about 9.2 GPH.  If I up the prop RPM to 2600, it will go to 142 knots, but my fuel burn will be just under 13.9 GPH.  At the other end of my usual altitude envelope, I will get 136 knots at 10,000 using 20 inches and 2400, which again is not quite WOT, and a fuel burn of about 8.5 GPH.  Again, if I take the prop to 2600, I can see 139 knots, but fuel burn will go up to 9.1 GPH.

I never run WOT except in climb (old superstition I guess), and never run at 2700 except in climb or above 10K.  The airplane burns less fuel above 10K, but is also slower by a few knots.  In a long range situation, I typically use 2300 RPM and can get the fuel burn under 8 GPH with the manifold setting above.  That gives a duration of over four hours at 10K and above.

One disadvantage of the carburated engine is that I cannot run LOP.  The manifold is just not good enough to give a narrow enough temperature spread.  I normally run 50 ROP on my hottest cylinder, and in some cases slightly richer if CHT temps drift to the high end.  I also like to have them all below 1350 anyway, irregardless of peak.

RFB

 

[Lood]

My normal flight usually takes place between 6k and 10k ft. Except when down at the coast, I always fly it at WOT and 2500 rpm and I get an average fuel burn of just under 10 gal/hr. MP at 7-8k ft is about 21". My Mooney does not have any mods and it normally indicates somewhere around 130 - 145 mph which is around 138 - 140 kts TAS. I am having the lower cowl closure and brake caliper rotation mods done next week and we'll see what the results are - if any.

[MikeinFL]

Thanks for everyone's reply!

I have a '68 M20F

Mike

[Guest Anonymous]

Sorry about the three-blade thing.  I guess I was thinking of podair's reply.

RFB