PT20J

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Good decision. Nowhere in your analysis did you mention looking forward to spending years of nights and weekends building an airplane. It’s a big commitment, and only if you find the building at least as enjoyable (maybe more so) than flying are you going to enjoy the experience.

It’s a good autopilot. However, some parts are no longer available (microprocessors, for example), used 28 V computers are becoming scarce, and units built in the mid-1990s have electrolytic capacitors that tend to leak and damage the PC boards. It’s questionable how long they can be maintained.

Where did you get the motor and what did it cost?

Well actually, p-factor is a propeller effect, but we know what you mean All that rotating mass did create a huge gyroscopic effect which reportedly the pilots used to their advantage during dog fights. Left turns were a snap so to speak. The rotary was very simple. All that spinning mixed the air and fuel so they didn't need carburetors. But that also meant that they didn't have throttles so they ran wide open and used a blip switch on the stick to cut out the ignition momentarily so they could land. They also used castor oil as a lubricant and the excess unburned oil exited the open exhaust ports and the pilots ingested it lubricating their digestive systems as well. According to one source, a bottle of blackberry brandy was often kept on board as an antidote. TBO was something like 50 hours.

The G3X includes a separately powered GSU 25 ADAHRS. The G5 has an internal ADAHRS. Both ADAHRS output to the CAN Bus. The GFC 500 software is contained in both the G3X and the G5. The G3X normally uses the GSU 25 and the G3X software to control the FD/AP. In the event of a hard failure of the GSU 25, the G3X will switch to using the G5 ADAHRS. I believe that the autopilot disconnects during the switchover and will have to reengaged. If the G3X GDU itself fails, the autopilot will disengage and can be reengaged using the G5. In the event of a soft failure of the GSU 25 ADAHRS (e.g., a miscompare error annunciated), it's a bit more complicated because you will have to decide whether the G3X or G5 is the aberrant unit. I installed a AV-20S as a tie breaker for this purpose. Then, assuming that the GSU 25 is the bad unit, you could pull the GDU circuit breaker disabling the G3X, or you could pull the GSU circuit breaker disabling only the ADAHRS. In the first case, you would revert to using the G5 including the autopilot. In the latter case, you would still have the G3X and autopilot available with the G3X reverting to using the G5 ADAHRS as described above. The rub here is that the G3X STC calls for installing the GSU 25 and the GMU 11 magnetometer on the same circuit breaker, so pulling that breaker also disables the magnetometer. I asked Garmin support why they did this and did not get a reasonable answer. Skip

There are several KA 33s on eBay for around $100.

Interesting. Mine is copyright 1995.

Did your installer fill out the configuration log in the maintenance manual and give you a copy? The maintenance manual is available on Garmin’s website.

I don’t think that the design is different - the J is derived from the F. But Mooney steering has a lot of places for slop to develop as parts wear. If your J has less lost motion than you are use to, it will seem a lot more responsive.

TABLE 9.2, p231 lists the -32W used in the F4U-5 as having a max SL hp of 2800.

It’s almost never the breaker, especially if it won’t reset. This breaker powers the annunciator panel VAC HI/LO warning circuit. There is also a current monitor in this circuit that is part of the standby vacuum pump installation but it is not described in the service manual. I would start by disconnecting the annunciator panel to see if that allows the breaker to reset. If so, the problem is in the annunciator panel itself. If that doesn’t clear it, I’d next investigate the current monitor.

Spark plugs can be fouled by lead or oil. Lead fouling became prevalent when 80 octane was discontinued and engines originally designed for it were forced to use 100LL which has a higher TEL content. One fix was to lean on the ground which increases combustion temperature which better activates the lead scavenger in the fuel. However, ground leaning may not produce enough heat to prevent oil fouling. The oil is usually getting past the rings which don’t seal as well at the lower cylinder pressures at near idle power. This is why an engine with low oil consumption can still foul plugs during prolonged ground operation. Some find that fine wire plugs help because the electrodes are smaller and more exposed to combustion temperatures. A cheaper alternative is BY plugs which have extended electrodes. I believe these plugs were developed for the O-235 engine in C-152s which was especially prone to fouling spark plugs. Skip

Not the engine per se, but Mooney has knowledge Continental does not have on the engine as installed in the airplane. The airplane manufacturer is the final authority regarding the airplane. That said, the only section of the POH/AFM that is regulatory and approved by the FAA is the Limitations section and that is clearly indicated in the document. So, you are free to conduct your mag check at any rpm you desire.

I used to volunteer at a museum with a lot of WW II era planes (P-51, Spitfire, Tigercat, Bearcat, B-25, DC-3 and a bunch of others). The planes all flew but generally only a few hours a year. The mechanic once noted that he had great job security because, “When they fly these old airplanes, they break, and when they don’t fly them, they break.”

I think they are all a bit unique. The old engine was burning a qt every 2 hrs and that’s how it got down to 4 once. The rebuilt one doesn’t change its use rate noticeably if I keep it between five and six compared to keeping it between six and seven. It did improve from 1 qt every 9-10 hours to 1 in 12 when I switched to X/C 20 w50 from straight 100.

What I noticed was that at 4 qts I got a temperature rise and a pressure drop. I haven’t seen a change in either pressure or temperature at 5 qts.

I believe all the M20Js have master cylinders with adjustable links. I think @kortopates said that the Encores had the master cylinders without adjustable links and someone else had written that Mooney at one time had adjustable links available for retrofit. There are also 1.5" extensions that don't require adjusting the master cylinder links. The 1.5" extensions are simpler to install and much less expensive. My M20J came from the factory with the 1.5" extensions installed. Skip

Paul makes an observation that TN is an aftermarket add-on while production turbocharged engines are boosted. The reason is that normalization is intended only to extend the altitude range of a NA engine. However, boosting allows a lower displacement (and thus smaller, lighter) engine to produce the same horsepower as a larger NA engine (or alternatively, the same size engine can be made to produce more power). This is because power output is limited by the amount of fuel that can be burned which is in turn limited by the amount of air admitted during the intake stroke. Boosting increases the number or oxygen molecules in the charge which allows more fuel to be burned and more power to be produced with the same displacement. Nothing is free, however, and boosting reduces the detonation margin. With a given octane fuel, the only ways to recover the detonation margin are to retard timing, decrease compression ratio, reduce the temperature of the charge or richen the mixture. Boosted engines use some combination of these, but primarily use reduced compression ratios which causes a loss in efficiency and gives rise to the differing LOP power vs fuel flow multipliers for turbocharged and NA engines. Reduced boosted detonation margin is also why turbocharged engines are so easily damaged by mixture mismanagement at high powers.

All the radial engines were supercharged with the supercharger in the rear driven from the crankshaft. The earliest ones were single stage, single speed superchargers. During WWII turbochargers were added to extend the altitude range for the B-17 and B-24. According to Herschel Smith's fascinating A History of Aircraft Engines, the reason the Merlin engine turned out to be a better engine for the P-51 was because it had a 2 stage, 2 speed supercharger whereas the Allison had a single stage, single speed supercharger having been designed to use turbocharging. But during the war, there was a shortage of tungsten for building General Electric turbochargers and the limited supply was allocated to the bombers. Later fighters such as the P-40 and P-38 got turbochargers.

I believe turbocharged engines are designed to be turbocharged and have fairly low compression ratios and run higher manifold pressure to generate rated power. Turbo normalized engines are generally NA engines with a turbo added to allow sea level manifold pressure to be maintained at higher altitudes. Actually, they are all correctly supercharged engines. The term turbosupercharger (shortened to turbocharger) was coined to differentiate it from mechanical (gear driven) superchargers.

I’ve come to believe that’s the case.

It's probably already vapor from the residual heat after the last flight. Everytime I open up the line to the transducer it is dry.

How old is the starter? Might be worth replacing it with a new lightweight Sky-Tec. They spin faster and make hot starts easier.