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Typical M20C speeds (TAS)


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Well, you'd have to have fuel flow equipment to answer that question. I was instead responding to your post from this morning that didn't reference fuel flows. Just GPS derived true airspeed, which is what I reported.

Yup, speaking to board vs. directly to you on that one Jim. The M20E has a fuel flow of 10.8GPH at 7500' (book) for max

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Agreed, Scott. FWIW, as a practical matter, I don't fly my J ROP anymore either.

Where this conversation becomes interesting to me, though, is that I can fly my J, which is both bigger and heavier, LOP at around 9 GPH or perhaps slightly less alongside the PowerFlowed C flying balls to the wall ROP at more like 11 GPH. Now that is an evolutionary improvement in efficiency as far as I am concerned that is way more impressive than the 11 extra knots that the J will do all out.

It's amazing what an additional 20 hp will provide...

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Actually, Gary, if you think that the increase in efficiency that I am referring to came from the extra horses you are missing the whole point.

speed mods made to the J + Horse Power has to add to your efficiency.  If that's not what you referring to... maybe you're right.

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Jim,

Shame on you for slamming "C" owners and their birds. No way you were refering to the awesome airframe clean-up by Roy and Mooney in netting vastly improved aerodynamics in your comparison to J and C side by side.

C=Napoleon=Rodney Dangerfield=Chip on my shoulder=I can't get no love

I say "All hail the 150knot "C"!! The magical 150knot wonder. "Hail"!

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Back in 1998, someone spent nearly $50k with mooneymart to mod my plane. Exterior changes included 201 cowl, windshield and various fairings. Later a power flow exhaust was added. I have yet to do a 3 way standardized run, but I would guess I'm averaging low 150's. My asi can be adjusted for temp and altitude, and it gives a similar value.

I think the power flow does increase fuel burn 1gph or so. I flew a 180 Cherokee for a while, and my 180hp mooney seems to drink a little faster.

I recently flew from gatlinburg and had to cruise at 8k. I was able to lean down to low 9's gph. Not lop territory, but not bad.

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Well, I must agree that these C's are indeed amazing. I did the 3-way speed test today and my F did a rather disappointing 141kt TAS.

Conditions were not very good - windy and a bit bumpy, so keeping things rock steady wasn't easy. Power settings were WOT, 100deg ROP, 2500rpm, 7500ft and a density altitude of around 8500ft. Fuel flow was 11gal/hr. I normally fly at 75 - 80 deg ROP (10gal/hr) and the 100 deg setting didn't seem to make any difference in performance.

I did the run twice and got 140kt on the first and 142kt on the second run. I have no speed mods on my F and the only add on is a Lasar lower cowl closure.

I had full tanks and was alone in the plane - 2400lbs or 341 below MAUW.

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I was just up this weekend in my "C", doing the break in on my engine, I was very happy with everything especially my speeds. I was indicating an average of 143kts at 4500ft, 25 squared. I let my garmin calculate my TAS and it was telling me 154kts. Even at 6500 ft I was in the yellow still indicating above 140kts. I added the cowl closure while the engine was out and did some minor clean up of parasite drag, the combination of all of the work probably increased my airspeed by about 10 knts.

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With your 201 cowl and windshield ... I am thinking you're buying lunch and I am nursing the wound?

Maybe some day "Mrs. Santa" will put those under our tree?

 

I dunno.  If you're getting 146-156k, it will be awful close.  Anyway, it's just an excuse to fly.   ;)

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Agreed, Scott. FWIW, as a practical matter, I don't fly my J ROP anymore either.

Where this conversation becomes interesting to me, though, is that I can fly my J, which is both bigger and heavier, LOP at around 9 GPH or perhaps slightly less alongside the PowerFlowed C flying balls to the wall ROP at more like 11 GPH. Now that is an evolutionary improvement in efficiency as far as I am concerned that is way more impressive than the 11 extra knots that the J will do all out.

Its part aerodynamics and part fuel injection is more efficient than a carbureted engine. I'd love to see an M20C with an IO-360-L2A engine on it. Its an 180HP parallel valve engine exactly like the C, but with fuel injectors in the cylinders. Its pretty efficient, and long-lived.  Better than the angle-valve engines in my opinion.

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That would be awesome! It's on some IO Lancairs and Super Decathlons. Less weight than the angle valve engine. That would be one Super C! Weight is still key I think on all these little airplanes. HP is good, but not at the cost of the angle valve cylinders these days.

Too bad it would now cost the value of an M20c to get it done!

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  • 1 year later...

Cleaned out my logbook, found these:

One March:

9000 msl, 150 mag, 146 track

20-1/2", 2500, 26°F

143 mph Ind, 167 knots groundspeed

One summer trip to the beach in NC:

9000 msl, 30.11", 57°F

20", 2500

137 mph Ind, 140 knots

Going home:

10,000 msl, 30.11", 53°F

20", 2500

135-140 mph Ind

Another beach trip home:

8000 msl, 68°F

~21-1/2", 2500

145 mph Ind

All are leaned 50°ROP, and MP / RPM are read from the factory needle; wish I had fuel flow! Indicated airspeed is in mph, groundspeed is in knots where recorded.

My groundspeed typically hovers around 140 knots in cruise; descents are usually 500 fpm and ~170 mph Ind; fuel burn is always around 9 gph except short trips at 3000 msl tend to be lower. My full groundspeed range in cruise flight is 68 - 183 knots. Guess which one is painful to see?

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  • 3 years later...

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