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Jason Baxter

Higher Than Normal MP

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Many thanks Tim, I have to admit I've rarely used the charts on ppg 300-313 and they were not available during most of beta because these are company charts (from an operator) whereas the charts on ppg 290-293 are the original Douglas data where the power is set reference to BMEP without having MP tablulated.  Also have to admit I've only used either MP or BMEP but not both and agree that they should correspond since they are related.  Interesting.  I'm sure Alex already has this on his todo list.


Dan Downs KCRP

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Tim,

The team wanted to have a little variance by engine and also over time and use. What you see comes from this, plus that no real world MAP gauge is that precise. If you use BMEP you are better synchronizing the engines but RPM of course need to in sync too. The single step of the throttle in the sim shows sometimes small differences too.


Happy flying!
Alexander M. Metzger

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On 3/25/2018 at 10:14 PM, downscc said:

Many thanks Tim, I have to admit I've rarely used the charts on ppg 300-313 and they were not available during most of beta because these are company charts (from an operator) whereas the charts on ppg 290-293 are the original Douglas data where the power is set reference to BMEP without having MP tablulated.  Also have to admit I've only used either MP or BMEP but not both and agree that they should correspond since they are related.  Interesting.  I'm sure Alex already has this on his todo list.

I think both references are used at the same time. MAP/RPM clearly define the steps for power settings during climb. BMEP is just a limit there not too exceed. Once you are in cruise climb or cruise you optimize RPM and BMEP and MAP may differ a bit. If it is a couple of inch, ice may have developed or a ignition circuit has gone bust, etc.


Happy flying!
Alexander M. Metzger

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4 hours ago, metzgergva said:

I think both references are used at the same time. MAP/RPM clearly define the steps for power settings during climb. BMEP is just a limit there not too exceed. Once you are in cruise climb or cruise you optimize RPM and BMEP and MAP may differ a bit. If it is a couple of inch, ice may have developed or a ignition circuit has gone bust, etc.

The Douglas manual is the opposite logic you suggest.  For example, pg 287 DC-6 Power Curve specifies BMEP rather than MP for power settings (max contin, METO,  enroute climb) and the tabulated TO power chart lists RPM/BMEP with a value for MP provided as a not to exceed.  None of the Douglas cruise power charts even tabulate MP.  I think it boils down to six of one or a half dozen of the other.  I always use the Douglas charts (RPM/BMEP) rather than the company charts (RPM/MP), and if I had a complete C-118 'dash-one' I'd be using that LOL.


Dan Downs KCRP

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Hello Alexander,

On 3.4.2018 at 2:58 PM, metzgergva said:

Tim,

The team wanted to have a little variance by engine and also over time and use. What you see comes from this, plus that no real world MAP gauge is that precise. If you use BMEP you are better synchronizing the engines but RPM of course need to in sync too. The single step of the throttle in the sim shows sometimes small differences too.

thank you very much for the explanation! I would still prefer a more precise MAP gauge but now I can at least understand the reasons behind it.

Does that mean that the false indication when the engines are off is also deliberately intended?  

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No instrument is perfect. At least not on an old plane  ;-)


Happy flying!
Alexander M. Metzger

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On 9.4.2018 at 8:32 PM, metzgergva said:

No instrument is perfect. At least not on an old plane  ;-)

That's true :smile: And it is great that you've taken all these small details into account. But how realistic is it that all four gauges have the exact same error margin? I mean if one gauge would show a little bit more and another one a little bit less it would be way more natural and believable. To be honest, the way it is at the moment it feels more like a bug than a feature. 

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4 hours ago, Tim-HH said:

That's true :smile: And it is great that you've taken all these small details into account. But how realistic is it that all four gauges have the exact same error margin? I mean if one gauge would show a little bit more and another one a little bit less it would be way more natural and believable. To be honest, the way it is at the moment it feels more like a bug than a feature. 

If you're looking for that dynamic and independent engine behaviour then you should take a look at the A2A Connie. No taking anything away from PMDG's DC-6 though, it is a great addon and by far the best DC-6 for FSX/P3D there is (and probably ever will be) but it's just not the same living & breathing beast like an accusim aircraft is. 


 

With kind regards, Bogdan Misko.

 

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On the topic of instrument errors: Unfortunately I didn't have much faith in the "out of calibration instruments explanation" for the MAP differences, so decided to test the theory with a measure of ambient pressure. I can happily report that the gauges are indeed indicating incorrectly (intentionally or not).. :cool:

The following image is with the engines shut down, in the Cold and Dark loaded state (sim was started with the Trike)

https://imgur.com/0CBZSug

You can see an indication of ~32" while measuring ambient pressure at KDAB (Daytona Beach, FL). ambient pressure was calculated to be 29.99" so the gauges reflect an error of 2" higher than actual MAP. It's interesting that all four instruments would indicate the same amount of error... and in the same direction :blink:

 

Robert Toten

Edited by randomTOTEN

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Robert, I think Alexander is aware of the problem and it will be resolved in an update... which year that happens I'm not guessing.

My solution is to use the BMEP in conjunction with the Douglas performance tables, which tabulate power settings in RPM/BMEP.  I think you'll find that the DC6 performance is pretty close to those tables, that was our attention during beta.  The addon RPM/MP tables came along after testing.  We had access to parts of it but our testing was based on the Douglas data.


Dan Downs KCRP

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