Slowest M20F ever?

[MikeOH]

Never mind...I now see your new post.

 

[Ronnie Pool]

Not sure I'm following...are you saying that if you pushed the throttle full forward in that photo (i.e. 3,000 feet) the plane would not have gone any faster???

I’m saying I did push the throttle up with no great effect in speed.


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[KSMooniac]

I wonder if you have low compression pistons installed, or an internal assembly error that throw the timing off.  I know of at least one case of a J that had an aftermarket turbocharger system removed, but the low compression pistons were NOT changed and that plane was a dog.  I don't know of an aftermarket turboCHARGER system for an F, though, but perhaps the engine came from something else?  Do you have the build records with part numbers for the engine components?

[Ronnie Pool]

I wonder if you have low compression pistons installed, or an internal assembly error that throw the timing off.  I know of at least one case of a J that had an aftermarket turbocharger system removed, but the low compression pistons were NOT changed and that plane was a dog.  I don't know of an aftermarket turboCHARGER system for an F, though, but perhaps the engine came from something else?  Do you have the build records with part numbers for the engine components?

I do have the build records. No turbo has ever been installed according to the logs.


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[KSMooniac]

12 minutes ago, Ronnie Pool said:

I do have the build records. No turbo has ever been installed according to the logs.


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I would double-check the pistons & rods that went into it against the Lycoming parts catalog.

[N201MKTurbo]

How does it climb? If it climbs well, then the engine is probably making power.

[Ronnie Pool]

How does it climb? If it climbs well, then the engine is probably making power.

No issues in climb as far as I can tell. It’ll climb at near 1500fpm although the cylinder temps aren’t allowing me to keep that angle for long.


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[N201MKTurbo]

Definitely something weird going on here.

[Joshua Blackh4t]

Having once left the gear down in my E and not realised until 7000 (i was very heavy, and a hot day. I was stressing about weight and blaming the performance on that) I can attest that the speed penalty is insane

So I would be starting with the gear. 100% check everything out that it folds back pefectly.

Good luck

[Ronnie Pool]

Having once left the gear down in my E and not realised until 7000 (i was very heavy, and a hot day. I was stressing about weight and blaming the performance on that) I can attest that the speed penalty is insane
So I would be starting with the gear. 100% check everything out that it folds back pefectly.
Good luck

This is current.


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[Ronnie Pool]

This is current.


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The left gear does seem to protrude a tad lower than the right when retracted but I’ve confirmed both are equal distance from the stops.


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[TheAv8r]

What is your MP / RPM / Fuel Flow on takeoff? Depending on your field elevation + density altitude, it should be around 29-30" MP, 2700 RPM and 19-20ish GPH. If it's nowhere near those numbers, that would indicate a control rigging or powerplant problem. I don't think the rigging would cause a 30kt speed penalty, it more of gains you 3-5kts.

[Ronnie Pool]

What is your MP / RPM / Fuel Flow on takeoff? Depending on your field elevation + density altitude, it should be around 29-30" MP, 2700 RPM and 19-20ish GPH. If it's nowhere near those numbers, that would indicate a control rigging or powerplant problem. I don't think the rigging would cause a 30kt speed penalty, it more of gains you 3-5kts.

It seems normal. RPM maxes at 2680-2690. with around 30 MP. Field elevation is 10ft and today at least was in the low 70s. GPH I honestly have not noted on takeoff.


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[Ronnie Pool]

2 things I may try when able:
#1 add weight to the baggage area.
#2 remove the landing gear doors and make a flight without them.


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[EricJ]

Just now, Ronnie Pool said:

2 things I may try when able:
#1 add weight to the baggage area.
#2 remove the landing gear doors and make a flight without them.


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What do you expect to gain by taking your gear doors off?    Those help a lot with speed and climb, even if they're a bit out of rig.

[PT20J]

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.

[Ronnie Pool]

What do you expect to gain by taking your gear doors off?    Those help a lot with speed and climb, even if they're a bit out of rig.

I doubt they are, but my worry is that they are flexing and causing a gap at the leading edge of the door.


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[bigmo]

I have the exact same plane 1970 F. Trues out at cruise (7k-10k) at 145 knots using 21/26 and 9.8gph (fuel is 9.6-10.2 depending on pressure).

Have you flown another similar year F to see if something feels really different?

If you were chasing down 3-5 knots, I could see lots of investigating…but 20 feels like power. The only other possibility to me is the CG wildly out of whack and a really odd angle of attack…and I can’t see that impacting it that much. I’ve had my wife choose the back seat a couple of times on trips when she wants to work on her laptop. Even with her back there, and our luggage in the rear, I see 2-3 knots faster…and the plane still feels the same.

The comparison flight might really help you realize where your issue is - ie a ‘oh my plane doesn’t do that’ moment.

[Ronnie Pool]

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.

I would tend to agree with you, but my pitot static was checked and signed off with myself involved only 2 months ago. There was a leak found but subsequent fixed. Plus, the ground speed doesn’t lie and has been consistent with the TAS and indicated wind speed. I would love it if that were the case! My ADSB tracks confirm my ground speeds as well.


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[Ronnie Pool]

I have the exact same plane 1970 F. Trues out at cruise (7k-10k) at 145 knots using 21/26 and 9.8gph (fuel is 9.6-10.2 depending on pressure).
Have you flown another similar year F to see if something feels really different?
If you were chasing down 3-5 knots, I could see lots of investigating…but 20 feels like power. The only other possibility to me is the CG wildly out of whack and a really odd angle of attack…and I can’t see that impacting it that much. I’ve had my wife choose the back seat a couple of times on trips when she wants to work on her laptop. Even with her back there, and our luggage in the rear, I see 2-3 knots faster…and the plane still feels the same.
The comparison flight might really help you realize where your issue is - ie a ‘oh my plane doesn’t do that’ moment.

I have not flown a similar plane unfortunately but would love to have that opportunity! My last Mooney was a C model with the O-320 and it was faster…smh. That was many years ago though.


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[MikeOH]

Just another reference point:  My 1970 F makes 143 kts @8,000, WOT, 2600 rpm, 8.5-9.0 gph LOP.

[takair]

I wouldn’t expect that droop in the gear to cause that much speed drop.  Maybe 5 kts….   
I was looking at your flight aware tracks and looked at a couple of out and back flights….so I would expect similar headwind vs tailwind.  On two of the longer flights, I rough calculated an average of about 134 kts.  That does not account for crosswind component, so not perfect science.  Also have no idea your power setting.  If 65%…that may not be awful….better than the 126 that is being displayed.  Might be worth a look at those flights to see if you recall the indicated and TAS.  It does sound like it could be indication.  Do you have alternate static?  Might pop that open and see if airspeed changes.   As others said, you can also do the GPS cross check or “formation” with a buddy who has relatively good readings.

I see you are at Eagle Neck.  Great place….have a good friend there….building a rocket and has an RV…you may know him.

[Ronnie Pool]

I wouldn’t expect that droop in the gear to cause that much speed drop.  Maybe 5 kts….   
I was looking at your flight aware tracks and looked at a couple of out and back flights….so I would expect similar headwind vs tailwind.  On two of the longer flights, I rough calculated an average of about 134 kts.  That does not account for crosswind component, so not perfect science.  Also have no idea your power setting.  If 65%…that may not be awful….better than the 126 that is being displayed.  Might be worth a look at those flights to see if you recall the indicated and TAS.  It does sound like it could be indication.  Do you have alternate static?  Might pop that open and see if airspeed changes.   As others said, you can also do the GPS cross check or “formation” with a buddy who has relatively good readings.
I see you are at Eagle Neck.  Great place….have a good friend there….building a rocket and has an RV…you may know him.

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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[KSMooniac]

The easiest way to rule out instrumentation errors is to do the 3-way test linked earlier.  I wouldn't bother trying to match POH numbers either as those were written by marketing and quite optimistic, especially in that era.  Better to do a real test and see if your instrumentation is close or not.  NA Mooneys should generally be flown with wide open throttle all the time too for best efficiency.

[Bartman]

If you have questions about RPM accuracy, I recommend downloading the "Engine RPM" app to your phone.  I discovered my engine and prop make full RPM, but the readings are not correct on the dial when I pull back the blue knob.  When reading 2500, it is more like 2400 on the app, which uses the microphone on your phone to sense impulses.  It's a cheap app, and I find it very useful.

I also see you have a digital tach which may eliminate this.