Manifold pressure in the Baron and the FSD Panther

[jfri 42]

When I fly the Baron 58 in the lessons I'm told that I need to continously adjust the mp. And the mp is indeed changing by changed altitude both in the default and DF Baron 58. But in the FSD Navajo Panther I don't see this. Does this mean that the FSD panther is lacking in realism here?

[zfehr 1]

No, the Baron 58 is a normally aspirated piston engine so you would expect to see the manifold pressure drop about 1" per 1,000 feet altitude as you climb. The Navajo is a turbocharged piston engine so it will maintain a set manifold pressure until climbing beyond its critical altitude (at which point the wastegate is fully closed), after that point you will see it also drop pressure as you continue to climb. That is also why you can achieve manifold pressure settings above 29" with the Navajo at sea level.

[Guest kickin_chicken]

Hi. The FSD Navajo is NOT turbocharged. It has two 540 cubic inch flat 6 cylinder engines and does not have turbo- or sucperchargers. The cabin of the Navajo, therefore, is not pressurized either. Now, for the OP's question, I never noticed the change in MP in the Navajo mainly because I fly in the 6000 to 8000 ft altitudes in this plane. I would not see much change in the manifold pressure, but I will have a look when I next fly this plane. In reality, the manifold pressure SHOULD change with altitude, but it might not in the FSD Navajo (for programming reasons, not because of turbocharging).

[zfehr 1]

>Hi. The FSD Navajo is NOT turbocharged. It has two 540>cubic inch flat 6 cylinder engines and does not have turbo- or>sucperchargers. The cabin of the Navajo, therefore, is not>pressurized either. >Now, for the OP's question, I never noticed the change in MP>in the Navajo mainly because I fly in the 6000 to 8000 ft>altitudes in this plane. I would not see much change in the>manifold pressure, but I will have a look when I next fly this>plane. In reality, the manifold pressure SHOULD change with>altitude, but it might not in the FSD Navajo (for programming>reasons, not because of turbocharging).Really, I grew up flying in a PA31-310, then a PA31-350 both of which were factory turbocharged... that's what the "T" in the TIO means in the engine number. There is a very, and I mean very rare PA31-300 which was not turbocharged and had a very short production run. There was also a pressurized version of the Navajo which was later fitted with turbine engines to become the Cheyenne. A normally aspirated piston engine would, on a standard day, achieve a max of 23" MAP at 6,000' and 21" MAP at 8,000'.Please know what you are talking about when you start to spout facts and if you want to challenge my aircraft knowlege you'd be wise to pick something besides the Navajo series, I'm pretty sure I had the PA31 series pretty well covered before you were born.

[jfri 42]

>Hi. The FSD Navajo is NOT turbocharged. It has two 540>cubic inch flat 6 cylinder engines and does not have turbo- or>sucperchargers. The cabin of the Navajo, therefore, is not>pressurized either. In the manual under load manager it is stated that'While the turboprop engine used in the Navajo'>Now, for the OP's question, I never noticed the change in MP>in the Navajo mainly because I fly in the 6000 to 8000 ft>altitudes in this plane. I would not see much change in the>manifold pressure, but I will have a look when I next fly this>plane. In reality, the manifold pressure SHOULD change with>altitude, but it might not in the FSD Navajo (for programming>reasons, not because of turbocharging).In the Baron 58 I see changes in mp far before reaching 6000 ft and in the Panther I see none even if I go above 8000 ft. Also I have noticed that the Panther is more powerfull than the Baron. It climb and cruise faster. Why if not turbo?

[Guest Mr Chips]

Yes, the Navajos are generally turbo-supercharged. The 24,000'ceiling tells a story. One would probably expect the MP to start dropping above 10,000' or so (as I guess?).However, FS is not very good at modelling the engineering of these things. For example the Seneca PA34 is fitted with fixed wastegate RayJay turbos. The fixed wastegate is linked to throttle position so MP still drops in the climb as would a normally aspirated engine, just that the full throttle altitude is much higher. I don't know about the wastegate on the PA31. If it is aneroid and engine oil pressure actuated then you will not see a drop in MP until the critical altitude (where the wastegate is fully closed).FS only models the latter type, with the former only achievable by setting the critical altitude to zero in the aircraft.cfg with greatly exagertaed HP. I messed about with the Just Flight Seneca and it now works much more realistically. There is still the issue that MP and RPM relationship is reversed with this setup (more MP = more RPM and visa versa).I'm waffling again, sorry :

[zfehr 1]

"While the turboprop engine used in the Navajo"Typo on FSD's part. The Navajo does not use a turboprop engine, they are turbocharged Lycomings.