Typical M20C speeds (TAS)

[Hank]

@Hair_Helmet, we have the same instrumentation and up-front mods, but I don't have powerflow. 

My usual power settings vary by altitude:

< 3500--23" / 2300

3500 - ~7000--22" / 2400

> ~7500--WOT- / 2500

I don't run WOT like our fuel injected brethren, I back off just enough to make the MP needle wiggle, so that the Auto Enrichment circuit is closed off. It is needed for full-power climb but not for cruise. I also run 50°F rich of peak.

Fly safe!

[Tcraft938]

Quite a coincidence I noticed this topic since this weekend I did some testing.  1963 D/C one piece windshield, new scimitar 2 blade prop, 100hrs on Penn Yan OH to new.  The day was 2 degrees C above standard, flying at 75% power or as close as possible and 25-50 degrees rich of peak.  I don't have a nice new engine monitor, so who knows how accurate the MP guage and FF are, but I know RPM and Static are dead on.  Just me and full fuel, so around 2100lbs 

7500'  22.5"/2300 TAS 149kts/172mph  8.8 gph

7500'  22.0"/2400 TAS 151kts/174mph  9.2 gph

5000'  23.0"/2300 TAS 146kts/168mph  9.4 gph

10,000 WOT 20.5"/2500  TAS 153kts/176mph  8.7 gph

I need to have the MP overhauled, since on the ground it reads about 2" lower than it should.  Engine running it seems to be within 1/2" and the performance and fuel burn numbers confirm that.  A new JPI would be going in next month at annual, but the IRS is going to take those dollars instead.  Errr

[takair]

2 hours ago, Hair_Helmet said:

-2400 rpm WOT with Autolean at 75 ROP for the last few 3 hour xc, 3 blade rpm restrictions..

What manifold pressure are you seeing here at WOT?  As Hank suggested, you may also have the auto enrichment in the carb active.  Back off throttle a little and see if you get a jump down in fuel flow without significant reduction in MAP and then run Auto-Lean to adjust mixture to try the same 75ROP.  Since that is likely your richest cylinder, the others are likely running closer to 100 ROP.  If you are under 75%....some would argue less than 65%.... you might try adjusting number 3 to 50 ROP....which will likely put the others closer to 75 ROP.  It is best with an analyzer to you can watch CHTs......as you already suggested.

[carusoam]

Carb lesson...102.

How to turn off the enrichment circuit...

That secondary fuel nozzle that is good for spraying extra fuel during WOT climbs...

Good to know how to turn it off, once the climb is over... and efficient cruise has begun...

Need to put this in the carb vs. FI discussion...

Best regards,

-a-

[cliffy]

Once you start to lean with the mixture control the auto enrichment circuit is out of the picture NO added fuel flow once you pull on the mixture control and get an EGT rise. 

The mixture controls the total fuel flow amount to the engine. 

If you don't believe it set up your cruise power with WOT and lean to 50 rich. Then pull back on the throttle a little to get a slight MP decrease. If the enrichment circuit was working you'd get a rise in EGT as the extra fuel was taken away by the throttle movement. 

If you fly high enough to lean for best power or economy then you can leave the throttle wide open. No extra fuel will be flowed through.  

[Hank]

By NOT leaving the throttle fully open, airflow through it is less smooth and hopefully even turbulent. This will better atomize the fuel coming in, and certainly mix it up better for (hopefully) more uniform distribution. Between this and partial carb heat, it is often possible to cruise at LOP settings. If not, find and fix your induction leaks--mine were coming from the carb heat box, where the flapper hinges were failing.

[Mooneymite]

Looking through this thread, I'm beginning to think I have a one-of-a-kind Mooney. 

My 74 C is completely stock...no speed mods at all, and on any given (standard atmosphere) day, it delivers "book numbers".  I know the pre-68 Mooney book numbers were a little bit on the optimistic side, but by 74, the numbers were much more realistic.  This is part of the reason people believe the older Mooneys were faster.

In cruise flight, I can set the book power settings and get almost precisely the book FF and TAS...adjusted to standard atmosphere and IAS error.

Can you imagine such a thing?

[Tcraft938]

20 minutes ago, Mooneymite said:

Looking through this thread, I'm beginning to think I have a one-of-a-kind Mooney. 

My 74 C is completely stock...no speed mods at all, and on any given (standard atmosphere) day, it delivers "book numbers".  I know the pre-68 Mooney book numbers were a little bit on the optimistic side, but by 74, the numbers were much more realistic.  This is part of the reason people believe the older Mooneys were faster.

In cruise flight, I can set the book power settings and get almost precisely the book FF and TAS...adjusted to standard atmosphere and IAS error.

Can you imagine such a thing?

You have a very studious C model that obviously read the POH and does as expected rather than wait for an all knowing pilot to claim they make it better with their golden touch.  :-)    To one of your points I recently compared my 1963 POH to a 1965 and 1970 and found the 63 and 65 performance charts with few differences but some substantial ones between the 1970 and the earlier ones.  The 1970 has lower TAS and fuel burns.  However the 1970 talks about taking into consideration the climb and descent portion of flight.  So I am interpreting the 1970 to be more of a flight planning model, where the other two our performance charts for once you're at altitude, power set and stabilized?

Speed/efficiency can be largely impacted plus or minus by control surface rigging and as I learned engine alignment.  Last annual, per Don Maxwell article the A&P took great care to shim the engine accordingly.  It actually had a fairly significant improvement in speed and CHT's came down a bit, but more importantly all 4 are pretty similar in CHT in all phases of flight

[Rusty Pilot]

28 minutes ago, Mooneymite said:

Looking through this thread, I'm beginning to think I have a one-of-a-kind Mooney. 

My 74 C is completely stock...no speed mods at all, and on any given (standard atmosphere) day, it delivers "book numbers".  I know the pre-68 Mooney book numbers were a little bit on the optimistic side, but by 74, the numbers were much more realistic.  This is part of the reason people believe the older Mooneys were faster.

In cruise flight, I can set the book power settings and get almost precisely the book FF and TAS...adjusted to standard atmosphere and IAS error.

Can you imagine such a thing?

I notice I generally exceed book numbers on my 74C, but I have most of the speed mods.  It does especially well on climb.

[Mooneymite]

8 minutes ago, Rusty Pilot said:

I notice I generally exceed book numbers on my 74C, but I have most of the speed mods.  It does especially well on climb.

A pilot can contribute to overall efficiency by flying an efficient profile and route.  A few extra knots will have a hard time compensating for the pilot who flies a B-52 pattern at his destination.   Careful pre-flight planning for optimal wind and ATC routing can save more fuel than all the mods.

Back in the halcyon days of Southwest Airlines when they were so intent an shaving every possible minute from their flight times, we joked that SWA stood for "Seldom Wants Active" because SW would always request the runway that would get them to the gate quickest.  I was told it was hard to beat the efficiency of a 737 at the gate deplaning with the engines shut down.

Speed and efficiency are measured by more than just cockpit instruments.

[cliffy]

Best TAS and Trip time/speed are two different things. Airplanes aren't rated on trip time only TAS. 

CG also plays a good a part in TAS. Way nose heavy and speed suffers. Check your loading if you are way slow. With two on board and being we are "heavier" pilots that ol' Bill Wheat speed displayed is slower than he could get. He could do a loaded weight speed run with the CG aft which most of us can't;

Those factory speed runs probably were "corrected" from actual instrument data to account for density altitude and bring it into hard altitudes like 7,000 feet. There is no way they could have flown at an indicated altitude of say 7000 feet and actually been at 7000 msl every time.

In my own D I am about 3-4 mph off of the "book" speed as well as I can tell. Pretty close for a 57 year old airplane with one gear up repair and many antennas and probably not rigged perfect (but close) and a 3 blade prop. 

My comments on WOT were to demonstrate the economizer function and not anything as far as speed was concerned.

Carb heat plays a good role in speed as mentioned, Many have leaky heat flappers and therefore have "thinner" air going up the throat of the carb. 

[Hair_Helmet]

1 hour ago, cliffy said:

Best TAS and Trip time/speed are two different things. Airplanes aren't rated on trip time only TAS. 

CG also plays a good a part in TAS. Way nose heavy and speed suffers. Check your loading if you are way slow. With two on board and being we are "heavier" pilots that ol' Bill Wheat speed displayed is slower than he could get. He could do a loaded weight speed run with the CG aft which most of us can't;

I'm looking into the MT Prop, should save 25 lbs or so off the nose, and maybe move the battery to the rear.  My wife and I combine for 425-450 in the front seats and that 3 blade Hartzell is a beast.  Typically keep 75-100 lbs in the baggage area all the time.  Recently did the dual AV-30's (still on the fence about them) and removed 15 lbs of instruments/pump.  I should have held off to go with the Dynon Skyview for the engine monitor combo.

[Hair_Helmet]

I appreciate all of the replies.  I've read a couple books on engine management but real world experience and guys like you help put things in context.  I'll be sure to implement the feedback with a flight tomorrow, schedule permitting.

We recently smoothed out the top of the plane, no antennas.  Comm to the belly with the less drag bent whip, elt inside the fiberglass dorsal mod.  Lookin for a place to put a flush mount marker beacon antenna.  Transponder fin will go away once the tailbeaconx is available making for a smooth belly (cept for the 1000 screws.)  We've successfully picked up .74 microknots.

[cliffy]

Again a good wax job will yield 10+ KTS  :-) :-) (or so they say?)

AH the quest for speed-

No secret to speed - HP and $$$$$$$$

Edited March 30, 2021 by cliffy
add

[Hair_Helmet]

9 minutes ago, cliffy said:

Again a good wax job will yield 10+ KTS  :-) :-) (or so they say?)

AH the quest for speed-

No secret to speed - HP and $$$$$$$$

Best bang for the buck, a well maintained stock aeroplane with a good wax job.

The curse of the innovator's mind... good isn't good enough.  As long as it's balanced by the pocket book, why fight it?  I'm sure the last check I write will bounce off my plane.

[Mooneymite]

6 hours ago, cliffy said:

Best TAS and Trip time/speed are two different things. Airplanes aren't rated on trip time only TAS. 

Agreed!

My point was that pilots get all wrapped up with TAS, but except for bragging rights, TAS is just one component of what we are actually interested in:  Getting from point A to point B in the shortest time.  For Mooney pilots add in "for the least fuel".

Someone once opined on MS that, as far as speed mods are concerned, it's about 1 AMU per knot.  I've saved a lot of money by just leaving for my destination 3 minutes earlier.  

[Hair_Helmet]

2 hours ago, Mooneymite said:

I've saved a lot of money by just leaving for my destination 3 minutes earlier.  

Trouble is I'm "that guy" who is always late.  More speed for me is one part compensating, one part fascinating.

[Hair_Helmet]

4 hours ago, bluehighwayflyer said:

A good wax job is actually good for about 3 knots in a Mooney.  The CAFE Foundation performed this very test on a Mooney 20 or 30 years ago using very precise instruments and techniques.  Their report is available online somewhere and is an excellent read.  

That experimental Cafe E is a few hangars down from mine.  The owner of the E did most of the work on my C restoration.  He's currently going through the long process of field approvals for the mods going back to certified to free himself from experimental/certified limitations.

[MIm20c]

I don’t long for more speed from my C, only longer legs. I’ve only seen one C for sale with LR tanks.  I passed on one E with LR tanks and aero comfort interior awhile back.  As I flew away after inspecting the aircraft, knowing five other buyers after me were ready to pounce, I had a knot in my stomach that I might regret it.  To be honest the only thing I regret/miss is the LR tanks.

[Hair_Helmet]

33 minutes ago, bluehighwayflyer said:

Wow.  I remember when that plane was for sale a few years ago and had always wondered what had happened to it.  Very cool. Thanks for the update.  I have a copy of an old Sport Aviation article that Brien Seeley wrote about it’s  modification process around here somewhere.  A fascinating story with equally fascinating results.  To me and probably most of us here on MooneySpace, at least.

Jim

Kyle Kennedy bought it, he had been the GM at Lasar before the current owners.  We both flew from KLS to Sunriver last summer for the West Coast Mooney event with his Cafe and my new C.  He lives in Michigan now, and another former Lasar manager, Chris,  is assisting with the re-certification here.  I told him next time he's in town we gotta do a video interview on it. 

Not the best picture but apparently the only ones I took at the Sunriver event.  Throttle body injected, custom intake manifold to balance out the flow, high compression, funky cowl with huge spinner.... list goes on and on.  He did 200mph IA on 8gph that trip (don't quote me on that.)  My C behind his to the right.

Edited March 31, 2021 by Hair_Helmet

[Skates97]

2 hours ago, Hair_Helmet said:

Kyle Kennedy bought it, he had been the GM at Lasar before the current owners.  We both flew from KLS to Sunriver last summer for the West Coast Mooney event with his Cafe and my new C.  He lives in Michigan now, and another former Lasar manager, Chris,  is assisting with the re-certification here.  I told him next time he's in town we gotta do a video interview on it. 

Not the best picture but apparently the only ones I took at the Sunriver event.  Throttle body injected, custom intake manifold to balance out the flow, high compression, funky cowl with huge spinner.... list goes on and on.  He did 200mph IA on 8gph that trip (don't quote me on that.)  My C behind his to the right.

Thread drift......

It was cool to see it there. My D is three rows back, almost in line with the CAFE plane. This was the sun coming up through the smoke the morning we left.

But this one is possibly my favorite, turning base, my wife took it.

[carusoam]

Richard,

Your wife is an artist!

If MS had an art prize... she just won it!

Best regards,

-a-

[Hair_Helmet]

Great pictures, Richard...  worthwhile thread drift.

[rwabdu]

Question for you all, sounds like some of you are leaning at mixture settings above 75% BHP? ie "Full throttle at 2500 rpm up to 9500 at most and a little over 10 gph"

I always thought settings above 23 x23 I had to keep the mixture in full on an o360 bellow 10,000 msl to stay below 75% bhp. Or, was that because my poh was written pre-engine monitoring technology? 

Edited June 6, 2023 by rwabdu

[Hank]

22 minutes ago, rwabdu said:

Question for you all, sounds like some of you are leaning at mixture settings above 75% BHP? ie "Full throttle at 2500 rpm up to 9500 at most and a little over 10 gph"

I always thought settings above 23 x23 I had to keep the mixture in full on an o360 bellow 10,000 msl to stay below 75% bhp. Or, was that because my poh was written pre-engine monitoring technology? 

Do you have Performance Tables inyour Owners Manual? I've attached mine for 5000 and 7500 msl. What year is your C? Mine is 1970.

The Key Number for our engines is 46; add your MP and RPM, keep the total 46 or less. For example, I often use 22" / 2400 at 4000-7000 msl, which is below 75% and very leanable.