Slowest M20F ever?

[takair]

1 hour ago, Ronnie Pool said:

Must be talking about Mr Kleen! Love it here! Yeah, I can probably get someone to do a formation, that would be a good idea. I’ve been setting the plane up on my test flights to match the book target at 2500 rpm 21-22 MP for the most part.


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I am talking about him.  Great guy!.  Also know Mr Mock, but haven’t spoken in some time.

[philiplane]

Pitot static tests do not test the accuracy of the airspeed indicators. There can be leaks in that part of the system, while the static side is perfectly tight.

That said, it takes a lot of poor rigging or open gear doors to cause more than 4-5 knots of speed loss. I think you have to start from scratch and analyze the engine power instruments, the airspeed indication system, the rigging, to be sure you're getting valid data and that the plane is reasonably rigged.

[Ronnie Pool]

I am talking about him.  Great guy!.  Also know Mr Mock, but haven’t spoken in some time.

Mock is my closest neighbor. I live right behind him.


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[DCarlton]

I’ve read the whole thread several times.  Totally shooting from the hip wild ass thought.  Is it remotely possible it has the wrong prop?  

[DCarlton]

5 hours ago, PT20J said:

The rigging looks good. The engine is new and makes static rpm and the climb is good. Sounds like instrumentation. The standard "pitot-static" check really only checks for static leaks - the pitot connection is just to balance pressure on the pitot to avoid damaging the airspeed indicator. It's easy to check the pitot system for leaks. Just pressurize the pitot somehow. The standard way is to use a long piece of surgical tubing and roll it up. I found that difficult to manage and bought a large diameter syringe and connected it to the pitot tube by a short piece of vinyl tubing with a few wraps of electrical tape at both the syringe and pitot to avoid any leaks. Be sure to cover or plug the pitot drain hole. This makes it very easy to set 150 kts on the airspeed indicator. Then note how well it holds for one minute. The spec in my M20J service manual is not more that 10 kts drop. If the pitot system is tight, it will do much better than that.

If it’s on jacks, a good time to check the airspeed safety switch too and see if the gear comes up at about the expected airspeed?  Another potential data point if I’m recalling the procedure correctly.  

[MB65E]

Flip your Garmin to knots so we can all talk the same airspeed. Check all the stops on the fuel servo.

-Matt 

[RescueMunchkin]

My last flight at 12k MSL, -8C,  my F did 115 KIAS (135 KTAS) at my cruise setting of 2400 rpm and WOT, leaned to 9 gph. I don't have the J windshield but almost all other speed mods.

Edited November 13, 2024 by RescueMunchkin

[A64Pilot]

19 hours ago, KSMooniac said:

It might be worth measuring the valve lift then.  Lycoming cams suck.  I lost 1/2 a lobe (#1/#2 intake) 9 years ago and that triggered my overhaul.  It could be that the internal timing is off as well (assembled incorrectly), but I don't know how to easily check that.

You can check that with a degree wheel and a dial indicator.

Look up how to “degree” cams for a very good explanation.

I’ve never checked an aircraft, used to build drag bikes decades ago and I always degreed the cams.

You do need to know what the lobe center number is though, if you can’t find that I guess you would have to get it from measuring a known good engine.

Edited November 13, 2024 by A64Pilot

[A64Pilot]

Do not go by pitot A/S, back in the day we had to do runs over ground reference points to determine A/S error which was error prone subject to interpretation etc, thankfully now there are GPS’s and Dr Ralph Kimberlin after much discussion with the FAA finally got them to accept GPS data, believe it or not but they fought abandoning the old inaccurate way.

As a GPS is an averaging thing speed wise it’s very accurate for speed as it averages errors out, I mean stupid accurate. From memory Garmin quotes .05 m/sec for steady state speed which is .1MPH?

Do the three way speed run referenced earlier in the thread and forget any other data, if there is a significant difference, then the other instrument is in error, not the GPS. Do it early in the morning in smooth air, if it’s rough at all pick another day.

Edited November 13, 2024 by A64Pilot

[Echo]

If in cruise, and wanting speed, throttle at firewall is the way.

[Slick Nick]

13 hours ago, DCarlton said:

I’ve read the whole thread several times.  Totally shooting from the hip wild ass thought.  Is it remotely possible it has the wrong prop?  

Quoted because I believe this deserves some exploration. 

[802flyer]

How is your climb performance? Do you have any data points of IAS/fpm/DA for pattern altitude as well as up higher (eg above 6k)? Time-to-climb for a climb to altitude around 10k ft can also be helpful. Understand you’re trying to keep temps down while breaking in cylinders, but people here may be able to compare reasonable cruise-climb profiles.


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[N204TA]

I don’t know, but it seems to me that you have a math problem.

The G5 in the first photo shows speeds in knots.  I can’t read the OAT but it looks like 56F.  119 KIAS at 3,000 feet, 30.04 altimeter setting, 56 degrees, computes to 126 KTAS.  
 

The G5 in the second photo shows speeds in MPH.  Assuming that was the same flight, I estimate the OAT around 37F.  133 MPH at 9,500 feet, 30.08 altimeter setting, 37 degrees, computes to 155 MPH TAS.  155 MPH = 135 Knots which seems about right for our M20Fs.

[Florian Guthardt]

On the photo in flight it looks like the red light for gear up is not on - it should be always when the gear ist up ( at least on the earlier models -TBC) maybe gear does not go all the way up in flight even if it does on ground on jacks? 

[Fly Boomer]

2 hours ago, Florian Guthardt said:

On the photo in flight it looks like the red light for gear up is not on - it should be always when the gear ist up ( at least on the earlier models -TBC) maybe gear does not go all the way up in flight even if it does on ground on jacks? 

Thanks for your contribution.  More people thinking about the issues presented by members means that the OP is more likely to get the correct answer. 

[Ronnie Pool]

On the photo in flight it looks like the red light for gear up is not on - it should be always when the gear ist up ( at least on the earlier models -TBC) maybe gear does not go all the way up in flight even if it does on ground on jacks? 

My light goes out after a certain power setting. I do plan to rig a camera to check the gear in case there’s any deflections, however, there is also the manual gear indicator on the floor that shows the gear is not moving from the up position.


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[Ronnie Pool]

Had some better results on today’s flight with higher power settings and after tweaking the pitot system. I can see there is still a slight slow leak that may be emanating from the single piece of old tubing that I neglected to replace from the cabin to the pitot tube. I’ll be replacing it in the future. That, along with bad math and higher than reasonable hopes is likely my largest discrepancy. The plane still requires slight right rudder to hold true so I may be loosing some speed from rigging issues. I’ll need a set of boards to see exactly where things are I think. I have a digital inclinometer, but without knowing exactly where 0 should be I’m only guessing/ assuming. As well, when I did the panel upgrades, I removed tons of wiring, tubing, AP systems, etc etc which pushed the CG forward a bit. I’ll keep tweaking and testing until I’m either satisfied or bored…lol. Thank you for all the suggestions and advice. I’ll be considering all of them as I continue to work on and enjoy this aircraft.
Below is a before picture from when I purchased the plane earlier this year.



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[Ronnie Pool]

I’ve read the whole thread several times.  Totally shooting from the hip wild ass thought.  Is it remotely possible it has the wrong prop?  

It has HC-C2YK-1BF with F7666A-2 installed and recently overhauled.


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[bonal]

Just want to say that is a beautiful F and looks like it’s going 150kph just sitting on the ramp.  Noticed your improvement on latest update and thought that’s better until I saw 26/2600 at 3k.  If I was flying my D at that power and altitude I would be over 150 or at least close. Unless I’m reading it wrong. Attached is at 2450 WOT something not adding up.

[takair]

4 hours ago, Ronnie Pool said:

Had some better results on today’s flight with higher power settings and after tweaking the pitot system. I can see there is still a slight slow leak that may be emanating from the single piece of old tubing that I neglected to replace from the cabin to the pitot tube. I’ll be replacing it in the future. That, along with bad math and higher than reasonable hopes is likely my largest discrepancy. The plane still requires slight right rudder to hold true so I may be loosing some speed from rigging issues. I’ll need a set of boards to see exactly where things are I think. I have a digital inclinometer, but without knowing exactly where 0 should be I’m only guessing/ assuming. As well, when I did the panel upgrades, I removed tons of wiring, tubing, AP systems, etc etc which pushed the CG forward a bit. I’ll keep tweaking and testing until I’m either satisfied or bored…lol. Thank you for all the suggestions and advice. I’ll be considering all of them as I continue to work on and enjoy this aircraft.
Below is a before picture from when I purchased the plane earlier this year.



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Ronnie

I have found that the poor man way of checking aileron rigging gets you pretty close to the boards. Simply check the aileron weights are streamlined and then check that the flaps are aligned with the ailerons.  This should set zero just the same as the boards. Elevator takes more work and math, but I’ve done it in a pinch. (I’ve double checked with boards).  On some models, like my early E, there was only one up stop on the outboard end of the flaps. Over time, they develop a slight twist, so the inboard side ends up with some reflex. I can’t recall when they added an inboard stop. 
 

Rudder rigging to ball centered can be worth a couple of knots. My E has a trim tab that gets bent.  Surprisingly sensitive and notable if it gets bumped. 
 

Can’t tell, do you have retractable step or fixed aerodynamic step. The retractable step is draggy when down. It also causes out of trim rudder. That combination can be worth 3 knots. The fixed step is smaller and less draggy and only worth about 1 knot. 
 

If you want to talk, Kleen knows how to get ahold of me. 
 

You are on the right track. All of the details do add up and can get even an old Mooney close the the optimistic book speeds. 
 

Pitot leak….did your plane ever have a Brittain Alt hold?  If so, they have an intentional calibrated  leak built in. Many are unaware and will troubleshoot for hours. If not, disregard.  

[Pasturepilot]

@Ronnie Pool where are you located? I’m in Atlanta and have travel boards, that I have not yet had a chance to use.  I’ll have a long stretch of time off coming up, and a C model that can fly chase if you want to look at gear doors in flight. If you want to meet up for a rigging party, PM me. 
 

[Ronnie Pool]

[mention=53537]Ronnie Pool[/mention] where are you located? I’m in Atlanta and have travel boards, that I have not yet had a chance to use.  I’ll have a long stretch of time off coming up, and a C model that can fly chase if you want to look at gear doors in flight. If you want to meet up for a rigging party, PM me. 
 

That would be awesome! I am near Savannah at a fly in community called Eagleneck 1GA0. A rigging party would be great, as I can make copies rather quickly and could possibly trade your time/ equipment usage for Avionics installation (I do avionics installs out of my hangar). Do you know if your boards are GSE #030003? Not sure if the C and F are interchangeable. I go to Atlanta regularly for family as well so could hit you up there if not here.


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[Ronnie Pool]

Ronnie
I have found that the poor man way of checking aileron rigging gets you pretty close to the boards. Simply check the aileron weights are streamlined and then check that the flaps are aligned with the ailerons.  This should set zero just the same as the boards. Elevator takes more work and math, but I’ve done it in a pinch. (I’ve double checked with boards).  On some models, like my early E, there was only one up stop on the outboard end of the flaps. Over time, they develop a slight twist, so the inboard side ends up with some reflex. I can’t recall when they added an inboard stop. 
 
Rudder rigging to ball centered can be worth a couple of knots. My E has a trim tab that gets bent.  Surprisingly sensitive and notable if it gets bumped. 
 
Can’t tell, do you have retractable step or fixed aerodynamic step. The retractable step is draggy when down. It also causes out of trim rudder. That combination can be worth 3 knots. The fixed step is smaller and less draggy and only worth about 1 knot. 
 
If you want to talk, Kleen knows how to get ahold of me. 
 
You are on the right track. All of the details do add up and can get even an old Mooney close the the optimistic book speeds. 
 
Pitot leak….did your plane ever have a Brittain Alt hold?  If so, they have an intentional calibrated  leak built in. Many are unaware and will troubleshoot for hours. If not, disregard.  

If the aileron weights being streamlined is a 0 indication, then my ailerons are rigged slightly up where the book says they should be 0 to 2 deg down…. The flaps are contacting the wing to body fairing so I’m not sure how much more up I can go with them but I’ll give it a shot. My step is fixed unfortunately and is not removable unless I drill some rivets. Below are some pictures for reference. Will hit up Kleen. Are or were you a Gulfstreamer? I am a COR rep on the large cabins.



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[Igor_U]

20 minutes ago, Ronnie Pool said:

That would be awesome! I am near Savannah at a fly in community called Eagleneck 1GA0. 

I had to look it up... It seems like a good community airport with long runway.

Few years back I spent year and half working at Gulfstream and flew few times with friend who based his RV9 at Hodges.

We even flew to Barbour island (another pilot had a house there) which is very close to Eagle Neck. I don't remember seeing it but we must have flown over it. 

 

I hope you sort out you plane, it really looks beautiful. Good luck. 

[Pasturepilot]

38 minutes ago, Ronnie Pool said:

That would be awesome! I am near Savannah at a fly in community called Eagleneck 1GA0. A rigging party would be great, as I can make copies rather quickly and could possibly trade your time/ equipment usage for Avionics installation (I do avionics installs out of my hangar). Do you know if your boards are GSE #030003? Not sure if the C and F are interchangeable. I go to Atlanta regularly for family as well so could hit you up there if not here.


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The boards have a Mooney part number on them (not the GSE number but close)  and placards that state which models they're used for. The F model is listed on each board's placard. 

And yes, we could absolutely work out a swap for avionics work!