kityatyi

Maximum range

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I am wondering what is the range of the PMDG DC-6 because the aircraft info - when selecting aircraft in the sim aircraft selection menu - says 4000 nm / 7400 km but when planning a flight in PFPX, one that was less than 3000 nm, using the PFPX profiles that came with the aircraft, I got en error message that the fuel required is more than the capacity of the tanks.

According to the PFPX profiles and the intro manual, the fuel capacity is 19932 pounds. Using the PFPX profiles, a flight from JFK to LHR would require approximately 29000 pounds of fuel, and the distance is less than 6000 km.

But even a flight from Minneapolis to St Maarten cannot be completed without a fuel stop, although the distance is only 4000 km.

Something is not right, this aircraft should be able to fly farther - and even its own info text confirms this, by stating a range of 4000 nm / 7400 km.

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From Wikipedia:

DC-6A (Cargo version)
2948nm at max payload
4317nm at max fuel

DC-6B (Pax version)
2610nm at max payload
4100nm at max fuel

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I am not talking about Wikipedia. I am talking about PMDG's very own info which states a range of 4100 nm. Even if I fly empty from KMSP to TNCM which is a flight of less than 2200 nautical miles, it requires 22000 pounds of fuel but the tanks can hold only 19932... 

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So even when the PMDG DC-6 is empty (no pax, no cargo) it cannot even fly 2000 nautical miles. This must be wrong. 
 According to PFPX, the trip fuel from KMSP to TNCM is 19005. Add reserves and even such a short flight is a no-go.

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The issue might be with PFPX or the data input in PFPX. I tried Simbrief with the following data:

KMSP-TNCM, alternate TIST

RST8 ALO DCT KK57K DCT KM45M DCT BNA J45 MCN DCT OMN Y585 ELMUC L451 SLUGO A638 PJM

Cruise: 1000 BHP

ZFW: 69968 lbs

Altitude: 11000

The result was a trip fuel of 16706 lbs and 9h41m of air time, which leaves sufficient room for alternate, contingency and reserve fuel.

 

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I hope that it's a PFPX data issue because I would really love to do some long hauls. I will actually do a test flight from JFK to LHR tonight with 40 pax and full tanks and see what happens.

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Good luck. Just make sure you slow down at cruise altitude. With a 1000 BHP cruise you might make it (Simbrief comes up with a trip fuel of 19663 lbs). Browsing through historical timetables, I noticed that often flights from KJFK to EGLL made a fuel stop at either CYQX, EINN or both. 

In addition, there are two different fuel tank layouts for the DC6: with 8 or 10 fuel tanks. The PMDG DC6 as 8 fuel tanks which obviously limits the range.

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My back of the envelope range is a maximum of 9 hrs based on typical burn of 2000 lbs/hr.  If you managed a 220 kt GS that would be just under 2000 nm, or if you could get 240 kt then you're looking at almost 2200 nm.  I never think of my range in terms of miles, it is always limited by time.

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If that is the case - then the performance info text is incorrect as it states a range of 4000 nm.

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2 hours ago, kityatyi said:

If that is the case - then the performance info text is incorrect as it states a range of 4000 nm.

I think you're not taking into consideration that the given range is a theoretical maximum based on perfectly optimised flying, in reality the range will be much less. It's the same with cars today, BMW might say their new car does 40 mpg, but in reality you're lucky if you get 30.

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PFPX DC-6 profile are based on 1000, 1100, 1200 and 1240 hp only (high blower I guess), but you can fly with a lower power setting, low blower only, and get a bit more "range".
Don't know if a 4000nm range is doable on a 8 tank configuration DC-6 though.

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There is no need to complicate or explain away this. The fact is that the info text is incorrectly lists a range of 4000 nm, as simple as that, The PMDG DC-6 is unable to fly even 2000 nm consistently. Even though a 737 NG can travel from Seattle to central Europe when empty and with a bit of luck as you said (numerous delivery flights did it), yet no one ever said that its range is 4500 nm. The -800 variant for example, has a range of approximately 2900 nm and the aircraft can do it without any issues and without needing luck. The PMDG DC-6, however, is hardly able to complete half of the range written in the performance info.

Wikipedia mentions a domestic variant and a trans ocean variant, of which the latter can hold more fuel, it seems PMDG modelled the domestic variant (this must be the 8 tank variant then), however in this case the performance info is misleading with its 4000 nm / 7400 km range statement. So bye-bye transatlantic flights...

The only hope is an expansion pack with the 10-tank longer range variant but I doubt such will ever happen.

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6 minutes ago, kityatyi said:

There is no need to complicate or explain away this. The fact is that the info text is incorrectly lists a range of 4000 nm, as simple as that, The PMDG DC-6 is unable to fly even 2000-2000 nm consistently. Even though a 737 NG can fly from Seattle to central Europe when empty and with a bit of luck as you said (numerous delivery flights did it), yet no one ever said that its range is 4500 nm. The -800 variant for example, has a range of approximately 2900 nm and the aircraft can do it without any issues and without needing luck. The PMDG DC-6, however, is hardly able to complete the half of the range written in the performance info. Wikipedia mentions a domestic variant and a trans ocean variant, of which the latter can hold more fuel, it seems PMDG modelled the domestic variant (this must be the 8 tank variant then), however in this case the performance info is misleading with its 4000 nm / 7400 km range statement. So bye-bye transatlantic flights. The only hope is an expansion pack with the 10-tank longer range variant but I doubt such will ever happen.

Nobody is complicating or explaining away anything. They're not wrong at all, you've just taken a statement and assumed it applies in all circumstances. The range of a DC-6 is 4000 nm, it could theoretically be done. It's a theoretical maximum, not a "you will achieve this always". You're also comparing apples with oranges when you bring the 737 into the discussion. The NG is vastly more technologically advanced aircraft, it's computers can alter all sorts of engine parameters automatically to ensure it burns fuel as efficiently as possible, the DC-6 is completely manually controlled. I'm sure if you turned off the automated engine control systems in the NG, you would never get the claimed range of it either. Even then, all of this excludes factors like weather, altitude, weights, balances etc. etc. The effects of these changes are a lot more apparent on a 50 year old aircraft than on a new NG with computers monitoring and tweaking everything.

As for the 10 tank vs 8 tank point, PMDG modelled an aircraft they had access to as closely as possible. It's very difficult to model an aircraft that you don't have access to, with the 737, 747 and 777 it is a lot easier because they are current aircraft still in production, data is a lot more readily available.

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You still don't seem to get the point. The range in the info block is simply not the range of the modelled aircraft. No way you ever fly not 4000 but even 2500 nm with this particular aircraft. The airplane is fine, the range stated is not since that is definitely not the range of the 8 tank variant. As Dan said a few posts above, a fuel consumption of 2000 pounds per hour is typical, we can safely use this data to calculate or plan. The tanks can hold 19932 pounds. With that in mind, 9-9.5 hours of flight are the absolute maximum, and we did not even add reserves yet. So no, 4000 nm cannot be done not even theoretically with this aircraft.  Not even 2200 nm consistently. Without pointing fingers, the fact is that the PMDG DC-6 is a domestic DC-6 with a maximum range of 2000-2200 nautical miles and the performance info text is wrong. 4000 nm is double of the range that the modelled aircraft is able to fly, so it's not just a minor difference where we can say "sure but theoretically it can be done". We are talking about a difference of over 8 hours flight time and this can not be done, ever, with this configuration...

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18 minutes ago, kityatyi said:

You still don't seem to get the point. The range in the info block is simply not the range of the modelled aircraft. No way you ever fly not 4000 but even 2500 nm with this particular aircraft. The airplane is fine, the range stated is not since that is definitely not the range of the 8 tank variant. As Dan said a few posts above, a fuel consumption of 2000 pounds per hour is typical, we can safely use this data to calculate or plan. The tanks can hold 19932 pounds. With that in mind, 9-9.5 hours of flight are the absolute maximum, and we did not even add reserves yet. So no, 4000 nm cannot be done not even theoretically with this aircraft.  Not even 2200 nm consistently. Without pointing fingers, the fact is that the PMDG DC-6 is a domestic DC-6 with a maximum range of 2000-2200 nautical miles and the performance info text is wrong. 4000 nm is double of the range that the modelled aircraft is able to fly, so it's not just a minor difference where we can say "sure but theoretically it can be done". We are talking about a difference of over 8 hours flight time and this can not be done, ever, with this configuration...

Looks like PMDG might have made a mistake then. Either way it's pretty irrelevant. As I said, they modelled the DC-6 as close as possible to the one they had access to.

BTW, you can't say "without pointing fingers" and "PMDG...... the performance info text is wrong" in the same sentence, since the latter half of the sentence directly points the finger at PMDG getting it wrong. FYI only.

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