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Pilot53

Some confusion

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Im starting to get the hang of flying the dc6 in XP, but I have a few questions.

1.  What is the proper way of loading fuel in this airplane, especially when not using full tanks?  What tanks do you fill first?  I couldn't seem to find a clear answer in the POH, aside from never having more in the outboard tanks than the inboards.

2.  Engine parameters dont match the charts at all.  I know its an old airplane, and the engines have been refitted several times etc, but the numbers are not just off by a little bit, they are not even close!  For example, today I flew a 4 hour flight over the rocky mountains and cruised at FL180 to avoid terrain and WX.  It always seems the the manifold pressure is too high and the fuel flow is too low vs the power charts.  Trying to set 1500 climb at FL 160 at a carb temp of -30 the chart shows that I should be using high blower, 2400 rpm, have a bmep of 177, and a fuel flow of 1075 lb/hr.  The first problem is I have no need to even use high blower, the mp never drops low enough, even at FL180.  I tried high blower to see what it would do and in order to not redline the mp, i had to reduce throttle so much that the bmep dropped to around 100 and fuel flow was less than 400.  Anyway, continuing in low blower flying at 177 bmep only produced a fuel flow in the 700's, but produced a manifold pressure of around 49, not even close to what is in the tables.

3.  Cruise was a similar situation, if I set power according to mp I get a fuel flow of less than 400, bmep of around 100, much slower speeds, and this is all in low blower when the chart shows that I should be in high blower at fl180.  

Either it seems like manifold pressure and fuel flow is not modeled correctly, or the charts are just completely off, not even in the ballpark.  This isn't just at high altitude either, i've flown around 8000 and have experienced similar results.

 

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Do not overthink fuel loading.  The easiest thing to do is to enter either 50% or 100% and let the load manager distribute the fuel, and tweak the amounts from there if you want a specific fuel setting.  I rarely set up a precise fuel load like one does in the jets.

Stick to the charts. When it says use high blower then use high blower.  Enroute climb from chart on pg 287 is 1400 BHP 2400 RPM 165 BMEP.   FL180 cruise at 1100 BHP is 2120 RPM 147 BMEP on high blower. Simple. The fuel flows and IAS may vary up to 3% but I think they got it pretty close.  Using the alternative tables is something I only do on occasion.

If there is a confusion over the role of BMEP vs MP.  Keep is simple, if you are using the original Douglas performance tables then forget MP and use BMEP.  If you are using the charts added by PMDG as a supplement beginning on pg 300 then use MP and forget BMEP.  These charts were provided by pilots that fly the DC6 in daily operation, and their verbal recommendation for climb was simple:  Use 2400/40.

You should need high blower above an altitude you cannot maintain desired MP at full throttle.  The simulation is pretty close to the POH in this regard and if you have significantly different results then maybe there is a problem with your weather injecting unrealistic atmospheric conditions?

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4 hours ago, downscc said:

Do not overthink fuel loading.  The easiest thing to do is to enter either 50% or 100% and let the load manager distribute the fuel, and tweak the amounts from there if you want a specific fuel setting.  I rarely set up a precise fuel load like one does in the jets.

Stick to the charts. When it says use high blower then use high blower.  Enroute climb from chart on pg 287 is 1400 BHP 2400 RPM 165 BMEP.   FL180 cruise at 1100 BHP is 2120 RPM 147 BMEP on high blower. Simple. The fuel flows and IAS may vary up to 3% but I think they got it pretty close.  Using the alternative tables is something I only do on occasion.

If there is a confusion over the role of BMEP vs MP.  Keep is simple, if you are using the original Douglas performance tables then forget MP and use BMEP.  If you are using the charts added by PMDG as a supplement beginning on pg 300 then use MP and forget BMEP.  These charts were provided by pilots that fly the DC6 in daily operation, and their verbal recommendation for climb was simple:  Use 2400/40.

You should need high blower above an altitude you cannot maintain desired MP at full throttle.  The simulation is pretty close to the POH in this regard and if you have significantly different results then maybe there is a problem with your weather injecting unrealistic atmospheric conditions?

Thanks for the clarification.  Ive been flying in xp11 mostly lately and I think that is the issue.  Well now I have a clear answer of what doesnt work in xp11, the engine model!  Makes sense since they made a few changes to it, I bet the flight model isnt quite right either.  Hopefully pmdg will release an update and not just forget about us dc6 flyers.  

I tried again in xp 10 and the results were much closer to the tables, in xp11 if I switched to high blower the bmep would not change, but mp would go up, so when I lowered the throttles to compensate I got a bmep of 60.  Still in xp10 the climb fuel flow is still only around 700 when the chart says 1000, and bmep is less than what the chart says it should be for a given mp and rpm, but when I get to cruise with high blower the numbers do seem very close.   The other thing that is strange still, even with xp10 default wx is that during climb I never get to a point where I actually need to switch to high blower, the manifold pressure never gets that low.  

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1 hour ago, Pilot53 said:

Ive been flying in xp11 mostly lately and I think that is the issue.

You should have led with that :-)

I haven't tried the DC-6 in XP11 yet (waiting for a -- fingers crossed -- official PMDG update at some point along the way here), but I can definitely confirm that my other planes that have been quickly updated for XP11 compatibility by the developers, but haven't yet had their engine parameters tweaked, have engines that are *way* too powerful in XP11.

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3 hours ago, racingmars said:

You should have led with that :-)

 

Yeah I guess so, at first I didnt think they tweaked the piston engine model as well as the jet engine model.  One other question I had was how do i get the nav comm radio to work?  I can only get the nav radio to work through the gps unit.

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I do not speak for PMDG but I am a DC6 beta and my expectation is that once the current FSX/P3D testing is completed and they release it to market then they will start making the improvements that we have into the XPL product and include XPL11 updates.  Regardless of what their plans actually are I doubt they will do any development or update to the XPL product until done with the FSX/P3D product, nothing else makes much sense really.

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