Post by Tom/CalClassic on Apr 3, 2019 20:24:44 GMT -5
Hi all,
I've been playing with the DC-7C, seeing what its limits are in range (and then in speed at long range).
I first looked at my Riddle DC-7C manual and checked the long range cruise chart. Seemed pretty straightforward and thus I took the SS up for a flight between LAX and Heathrow, hoping for some tailwinds. Well, that never happened and I ended up landing at Prestwick with only a few hundred pounds of fuel left. But I did get used to using the chart, which wasn't that hard since you would normally want to fly at the altitudes that give you the best range at a reasonable true airspeed. Yes, you can plug along at 8000-12000 ft and get somewhat better range (around 10%), but that would take forever.
So I thought I would put together a little text file for my use, and thought others might like it too. It really doesn't give you much over the Flight Planner and using the settings in the Handling Notes, though. At the default payload of 10,000 lbs it only stretches your range from 4050 to 4338 NM. But if you are straining to make London non-stop you might want to try it. Here's the file:
--------------------
DC-7C LONG RANGE CRUISE TABLE
This simplified cruise table should be useful for those attempting very long range flights, between 4050 and 4338 NM with the default payload. The correct range for the DC-7C is 4900 NM (still wind, max fuel, no reserves, add payload up to MTOW). This procedure should give about 5100 NM, only a 4% difference. This table can also be used to maximize payload, for charter or freight work. Note that Riddle only used Long Range Cruise when necessary for the payload and distance.
The Max Altitude value is for flight planning - you will get slightly better range if you reduce your altitude to 8-12,000 ft, but it will take longer. The altitudes listed will produce the proper range for the DC-7C and are needed for California to Europe polar flights (i.e. to get over the Rocky Mountains). Do not exceed these altitudes unless terrain requires it.
The CalClassic DC-7C has an empty weight of 82,000 lbs plus 10,000 lbs of default payload. With full fuel (51,000 lbs) this yields the MTOW of 143,000 lbs. This very long distance flight planning must assume that you do not have headwinds; you must land earlier if you do. Therefore we eliminate the 15% headwind reserve, but include a standard 3710 lb reserve per the Riddle DC-7C manual plus the holding and alternate reserves. After adding these reserves, this results in a maximum range of 4338 NM and elapsed time of about 17.28 hours. For slightly shorter flights or higher payloads see the worked examples at the bottom.
But for flights shorter than 4050 NM at default payload just use the Flight Planner notepad and fly using the power settings in the Handling Notes. Always check if your flight is possible using the Flight Planner first. The transition between High Weight Cruise and Low Weight Cruise will occur somewhere around 125,000 lbs.
If you do need to use Long Range Cruise, then when your weight is in the Weight Zone below, set the RPM and fuel flow to the given values. All flight is performed in low blower (low supercharger).
WORKED EXAMPLES:
Number 1: Long Passenger Flight
Distance: 4100 NM
Empty Weight: 82,000 lbs
Payload: 10,000 lbs
We would like the fuel load required, and the approximate flight time.
1. Start with a 3710 lb reserve, and diversion and hold reserves (45 minutes each at the lowest weight, 1533 lbs).
3710 + 1533 + 1533 = 6776 lbs of reserve fuel.
2. Add this value to the empty weight (82,000 lbs) and payload (10,000 lbs in this example):
6776 + 92,000 = 98,776 lbs. This is the weight at which we would normally land at our destination with no delays. This must be less than 111,000 lbs.
3. Starting at that weight, we are in the 102,500 to 97,500 weight zone. Calculate the difference between the top of that weight zone and our weight:
102,500 - 98,776 = 3724 lbs.
4. Divide the remainder by the entire difference of that weight class:
102,500 - 97,500 = 5000
3724 / 5000 = 0.75
5. Multiply that by the NM column in the same weight zone:
0.75 x 585 = 439 NM
6. Subtract from 4100 NM the distances in the NM column, from the partial distance we just calculated towards the top until less than the next value higher.
4100 - 439 - 565 - 541 - 518 - 496 - 480 - 464 - 447 = 150 NM left over. The next weight zone higher is 143,000 to 137,500 lbs and has a distance of 337 NM, larger than 150.
7. Divide the remainder by the NM value of that higher weight zone.
150 / 388 = 0.39
8. Multiply this value by the total weight difference in the weight zone. In this case:
143,000 - 137,500 = 4500 lbs.
0.39 x 4500 = 1755 lbs.
9. Thus we will need to add 1755 lbs to the weight of the previous class:
137,500 + 1755 = 139,255 lbs. This is the weight of our aircraft at takeoff (TOW). It must be less than 143,000 lbs.
10. Subtract the empty weight (82,000 lbs) and payload (in this case 10,000 lbs) from this value.
139,255 - 92,000 = 47,255 lbs of flight fuel. Load this fuel into the plane. It must be less than 51,000 lbs.
11. Thus our first cruise power setting will probably use the 143,000 to 137,500 weight zone values.
12. Our approximate flight time will be:
The partial weight zones:
0.75 x 2.34 = 1.76 hrs
0.39 x 1.64 = 0.64 hrs
1.76 + 2.23 + 2.10 + 2.06 + 1.95 + 1.92 + 1.82 + 1.80 + 0.64 = 16.28 hrs
Number 2: Long Charter Flight
Distance: 3500 NM
Empty Weight: 82,000 lbs
Payload: 17,000 lbs
1. 6776 lbs reserve fuel
2. 6776 + 82,000 + 17,000 = 105,776 lbs landing weight.
3. In the 107,500 to 102,500 weight zone.
107,500 - 105,776 = 1724 lbs.
4. 107,500 - 102,500 = 5000
1724 / 5000 = 0.35
5. 0.35 x 565 = 198 NM
6. 3500 - 198 - 541 - 518 - 496 - 480 - 464 - 447 = 356 NM left over.
7. 356 / 388 = 0.92
8. 143,000 - 137,500 = 4500 lbs.
0.92 x 4500 = 4140 lbs.
9. 137,500 + 4140 = 142,640 lbs at takeoff.
10. 142,640 - 82,000 - 17,000 = 43,640 lbs of fuel to load.
12. 0.35 x 2.23 = 0.78 hrs
0.92 x 1.64 = 1.51 hrs
0.78 + 2.10 + 2.06 + 1.95 + 1.92 + 1.82 + 1.80 + 1.51 = 13.94 hrs
Tom Gibson 3/2019
I've been playing with the DC-7C, seeing what its limits are in range (and then in speed at long range).
I first looked at my Riddle DC-7C manual and checked the long range cruise chart. Seemed pretty straightforward and thus I took the SS up for a flight between LAX and Heathrow, hoping for some tailwinds. Well, that never happened and I ended up landing at Prestwick with only a few hundred pounds of fuel left. But I did get used to using the chart, which wasn't that hard since you would normally want to fly at the altitudes that give you the best range at a reasonable true airspeed. Yes, you can plug along at 8000-12000 ft and get somewhat better range (around 10%), but that would take forever.
So I thought I would put together a little text file for my use, and thought others might like it too. It really doesn't give you much over the Flight Planner and using the settings in the Handling Notes, though. At the default payload of 10,000 lbs it only stretches your range from 4050 to 4338 NM. But if you are straining to make London non-stop you might want to try it. Here's the file:
--------------------
DC-7C LONG RANGE CRUISE TABLE
This simplified cruise table should be useful for those attempting very long range flights, between 4050 and 4338 NM with the default payload. The correct range for the DC-7C is 4900 NM (still wind, max fuel, no reserves, add payload up to MTOW). This procedure should give about 5100 NM, only a 4% difference. This table can also be used to maximize payload, for charter or freight work. Note that Riddle only used Long Range Cruise when necessary for the payload and distance.
The Max Altitude value is for flight planning - you will get slightly better range if you reduce your altitude to 8-12,000 ft, but it will take longer. The altitudes listed will produce the proper range for the DC-7C and are needed for California to Europe polar flights (i.e. to get over the Rocky Mountains). Do not exceed these altitudes unless terrain requires it.
The CalClassic DC-7C has an empty weight of 82,000 lbs plus 10,000 lbs of default payload. With full fuel (51,000 lbs) this yields the MTOW of 143,000 lbs. This very long distance flight planning must assume that you do not have headwinds; you must land earlier if you do. Therefore we eliminate the 15% headwind reserve, but include a standard 3710 lb reserve per the Riddle DC-7C manual plus the holding and alternate reserves. After adding these reserves, this results in a maximum range of 4338 NM and elapsed time of about 17.28 hours. For slightly shorter flights or higher payloads see the worked examples at the bottom.
But for flights shorter than 4050 NM at default payload just use the Flight Planner notepad and fly using the power settings in the Handling Notes. Always check if your flight is possible using the Flight Planner first. The transition between High Weight Cruise and Low Weight Cruise will occur somewhere around 125,000 lbs.
If you do need to use Long Range Cruise, then when your weight is in the Weight Zone below, set the RPM and fuel flow to the given values. All flight is performed in low blower (low supercharger).
Weight Zone Max Alt. RPM BHP Fuel Flow KTAS TIME NM
(lbs) (ft) (PPH/eng) (hrs)
143,000 10,000 2200 1680 686 237 1.64 388
to
137,500
137,500 14,000 2350 1690 696 249 1.80 447
to
132,500
132,500 16,000 2400 1655 686 255 1.82 464
to
127,500
127,500 16,000 2350 1560 651 250 1.92 480
to
122,500
122,500 18,000 2400 1525 642 255 1.95 496
to
117,500
117,500 18,000 2350 1425 608 252 2.06 518
to
112,500
112,500 20,000 2400 1385 596 258 2.10 541
to
107,500
107,500 20,000 2300 1295 569 253 2.23 565
to
102,500
102,500 20,000 2250 1220 535 251 2.34 585
to
97,500
97,500 20,000 2200 1145 511 249 2.70 670
to
92,000WORKED EXAMPLES:
Number 1: Long Passenger Flight
Distance: 4100 NM
Empty Weight: 82,000 lbs
Payload: 10,000 lbs
We would like the fuel load required, and the approximate flight time.
1. Start with a 3710 lb reserve, and diversion and hold reserves (45 minutes each at the lowest weight, 1533 lbs).
3710 + 1533 + 1533 = 6776 lbs of reserve fuel.
2. Add this value to the empty weight (82,000 lbs) and payload (10,000 lbs in this example):
6776 + 92,000 = 98,776 lbs. This is the weight at which we would normally land at our destination with no delays. This must be less than 111,000 lbs.
3. Starting at that weight, we are in the 102,500 to 97,500 weight zone. Calculate the difference between the top of that weight zone and our weight:
102,500 - 98,776 = 3724 lbs.
4. Divide the remainder by the entire difference of that weight class:
102,500 - 97,500 = 5000
3724 / 5000 = 0.75
5. Multiply that by the NM column in the same weight zone:
0.75 x 585 = 439 NM
6. Subtract from 4100 NM the distances in the NM column, from the partial distance we just calculated towards the top until less than the next value higher.
4100 - 439 - 565 - 541 - 518 - 496 - 480 - 464 - 447 = 150 NM left over. The next weight zone higher is 143,000 to 137,500 lbs and has a distance of 337 NM, larger than 150.
7. Divide the remainder by the NM value of that higher weight zone.
150 / 388 = 0.39
8. Multiply this value by the total weight difference in the weight zone. In this case:
143,000 - 137,500 = 4500 lbs.
0.39 x 4500 = 1755 lbs.
9. Thus we will need to add 1755 lbs to the weight of the previous class:
137,500 + 1755 = 139,255 lbs. This is the weight of our aircraft at takeoff (TOW). It must be less than 143,000 lbs.
10. Subtract the empty weight (82,000 lbs) and payload (in this case 10,000 lbs) from this value.
139,255 - 92,000 = 47,255 lbs of flight fuel. Load this fuel into the plane. It must be less than 51,000 lbs.
11. Thus our first cruise power setting will probably use the 143,000 to 137,500 weight zone values.
12. Our approximate flight time will be:
The partial weight zones:
0.75 x 2.34 = 1.76 hrs
0.39 x 1.64 = 0.64 hrs
1.76 + 2.23 + 2.10 + 2.06 + 1.95 + 1.92 + 1.82 + 1.80 + 0.64 = 16.28 hrs
Number 2: Long Charter Flight
Distance: 3500 NM
Empty Weight: 82,000 lbs
Payload: 17,000 lbs
1. 6776 lbs reserve fuel
2. 6776 + 82,000 + 17,000 = 105,776 lbs landing weight.
3. In the 107,500 to 102,500 weight zone.
107,500 - 105,776 = 1724 lbs.
4. 107,500 - 102,500 = 5000
1724 / 5000 = 0.35
5. 0.35 x 565 = 198 NM
6. 3500 - 198 - 541 - 518 - 496 - 480 - 464 - 447 = 356 NM left over.
7. 356 / 388 = 0.92
8. 143,000 - 137,500 = 4500 lbs.
0.92 x 4500 = 4140 lbs.
9. 137,500 + 4140 = 142,640 lbs at takeoff.
10. 142,640 - 82,000 - 17,000 = 43,640 lbs of fuel to load.
12. 0.35 x 2.23 = 0.78 hrs
0.92 x 1.64 = 1.51 hrs
0.78 + 2.10 + 2.06 + 1.95 + 1.92 + 1.82 + 1.80 + 1.51 = 13.94 hrs
Tom Gibson 3/2019
