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Post by blueaircraft on Jul 8, 2023 18:27:00 GMT -5
Hello everyone. I haven't been able to properly fly propliners simply due to not having enough time. Anyway, I stated that just in case that may be of importance later on in this post. I fly the DC-7B most times I play FS9 (707 comes in second), and I would like to know if I am flying the thing correctly. The route I fly the most is the Johannesburg to Perth Wallaby Route via stops in Mauritius and Cocos Isl. respectively. After applying METO power and going into climb (ie. 42 MAP and 2500 RPM) I find that the plane keeps climbing even up to 20000 ft (with around 70% fuel and a full payload - as in no emptiness to spare, from Cocos Isl. to Mauritius), with 175 IAS (sometimes 176 and 177) and a climb rate of more than 500 ft. When I apply economy settings at heavy weight (more than 115000 lbs according to the aircraft's reference page?) it flies at 287 TAS, in line with the Calclassic planner, but when the plane begins to "lighten" (ie. less weight due to fuel consumed) and I apply economy settings for medium weight and light weight (after more "lightening"), the plane slowly loses altitude (as in -50 ft or less, sometimes more, but nothing beyond -100) and thus IAS and TAS. Shouldn't it fly higher according to the Propliner tutorial and the aircraft's reference page? I would also state that the "42 MAP" that I apply after METO power start to "reduce" after around 9000 ft, and I steadily increase the throttle until it reaches 42 MAP once more, and I keep doing that until I reach 95% throttle, putting the superchargers at HIGH and reducing the throttle to 42 MAP. Sometimes I leave it at whatever MAP it reads after the superchargers are set to HIGH, but most times I do what I stated earlier. I have what the Calclassic planner states when I am parked and not ready to depart just yet.
For example, the planner on a trip from Cocos Isl. to Mauritius on the SAA DC-7B before departure
Max Cruise - 188 FT HW - 185 FT MW - 171 FT LW - 163 FT
The Propliner tutorial PDF states that the aircraft must lose weight and step climb so that it can reach its destination without delay, but why does my planner state that a lower altitude is optimum? What am I doing wrong? Also most of the time I fly in FS' "Fair Weather setting." (I never fly with the "clear skies" option.)
Regards Andrew
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Post by Tom/CalClassic on Jul 9, 2023 10:32:03 GMT -5
Hi,
Looks like you are doing everything right, but are perhaps a little confused about the flight planning goals (and if our docs caused this I’m sorry about that).
The DC-7B was the fastest of all the Douglas piston airliners, so good performance below MTOW is to be expected. I assume you are using the international version, BTW.
The confusion may arise because there are different goals in flight planning, and the way you fly will thus be different. We’ll look at each one.
First is the case where range is not a problem and the time of the trip is the important thing to beat the competition. In this case once the weight begins to go down you keep the power levels reasonably high and step climb to get as high (and fast) as possible. By the end of a reasonably long flight you should be very high and very fast.
Second is the case where range is the important factor, and competition less important. In this case once the plane lightens, you lower your power to keep the same overall speed. Step climbing becomes less important, and you might not ever get very high.
In the reference file if you see “economy”, we are talking the second case, lowering your power as you burn off fuel. You will step climb when you can, but they will be few and far between. If you want to fly the first case keep your power levels at the high weight setting and step climb every chance you get. Once you get to the service ceiling you might need to reduce power to avoid over speed, but that’s about it.
Hope this helps,
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Post by blueaircraft on Jul 9, 2023 19:55:59 GMT -5
Thanks Tom. I'm flying the Westbound route from Cocos Islands to Mauritius right now... and I've reached around 21000 FT, with a cruising speed of 305 TAS, on headwind cruise settings due to a 22 mph headwind (on fair weather). The planner initially stated that I had a perceived headwind as I levelled off around 10000 FT earlier in the flight, but the statement eventually went away and currently not on display. Is this accurate for an "International" DC-7B? Or is something wrong with the flight dynamics (on my part, not the Calclassic FD itself)? My takeoff weight was a tad more than 126100 lbs (and thus had to takeoff with AF), but now it's around 115500 lbs. I have the current location of the aircraft below. imgur.com/V36njEuTake a look at my current aircraft location. The flight distance is in total around 2305 nm. I believe that we still have 1900-1500 (??) nm to go. I'm around FL 21, TAS 305, 115500 lbs, and using max cruise settings to battle a 20 mph headwind. Also, I departed at 2320, and should arrive at Mauritius at 605 according to the September 1959 BOAC timetable for the Australian-South Africa service. The plane seems to be reaching its operational cruising ceiling somewhere at FL 21 or 22, at least until it becomes lighter (sometime later during flight). But should the aircraft fly that high that early, and with that weight? Regards Andrew
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Post by Tom/CalClassic on Jul 10, 2023 9:02:08 GMT -5
I’m sure it could fly that high at max cruise, but I are you at the optimal altitude? Is the headwind less at lower altitudes, i.e. what was your TAS before the last step climb? Do you have enough fuel for the rest of the flight at that power setting?
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Post by blueaircraft on Jul 10, 2023 11:18:56 GMT -5
I believe so, but I would say that I did a gradual step climb ie. the aircraft kept a steady climb rate at around 50-100 feet per minute since levelling off, until reduced at around 8-3 fpm at FL 21500. Reached 0-1 fpm around FL 21800. Headwind was slightly less at lower altitudes, but even with max cruise settings did not achieve 303 TAS likely due to lower altitude. Headwind is 25 knots from FL 19 to present altitude, but was slightly lower at 22 knots. I do have enough fuel at that power setting, and I've reached halfway across my flight.
Regards Andrew
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Post by Tom/CalClassic on Jul 10, 2023 11:39:36 GMT -5
Generally speaking, you should not step climb in controlled territory unless you can maintain a 500 rpm climb rate. While slow climbs were occasionally used for very long distance flights at low power levels, in these conditions you would not do that.
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Post by Tom/CalClassic on Jul 10, 2023 14:36:38 GMT -5
Let's check out the reference document and see what it says about this.
First, the ref file says this about Max Cruise Power: 1. Only used to fight headwinds, which is your case. 2. Plan 3000 PPH - so based on your current TAS you can calculate if you have enough fuel at this power setting. If not, you need to do something else - probably lose altitude until you find lower headwinds (hopefully). If that doesn't work, search for an alternate airport that is closer. 3. It says you may be nose down since you are pouring on so much power - so be it. But this means you should have plenty of power to step climb to increase your TAS. But if at the moment you are not at least nose level (0 pitch) and are nose up it probably makes no sense to climb. Your TAS will probably drop the higher you go at this point. Typical propliners were most efficient when flying nose level or just nose up from that. Once you are nose level you should be able to climb another 2000 ft. at 500 fpm. Climbing too soon only makes the passengers uncomfortable with the nose up attitude and the plane less efficient.
The next power setting - Econ Cruise at Max Weight - says:
1. Standard Cruise Power. This is what I meant when I said if fuel is not an issue (and you have small headwinds or better) this would be the power setting you would use for the entire flight. 2. Standard Cruise: @ 0 pitch climb 2000 ft at 500 fpm (FL230 max, then CALL for MW Econ Cruise, if desired). This says you will stay at this power setting all the way up to your maximum altitude. Then you have a choice - stay at Standard Cruise Power to save time or go to MW Econ Cruise to save fuel. That will depend on the route length and the timetable. 3. Long Range Cruise: @ 0 pitch CALL for MW Econ Cruise. If you are instead concerned about fuel, you will immediately go to MW Econ Cruise as soon as you reach 0 pitch. Any step climbs will be at this power setting.
The next power setting - Econ Cruise at Mid Weight - says: 1. Use for standard long range cruise power. So when flying long ranges, you will use this power setting as your "standard". 2. Standard [Long Range] Cruise: @ 0 pitch climb 2000 ft at 500 fpm (FL250 max, then CALL for LW Econ Cruise, if desired). You will transition to this from Max Weight Cruise Power when you reach 0 pitch, then keep this power setting until you reach your maximum altitude, using step climbs. Then another choice - stay at this MW Econ Cruise or go to LW Econ Cruise if fuel is critical. 3. Long Range Cruise: @ 0 pitch CALL for LW Econ Cruise. When flying very long flights and fuel is critical from the start, you will instead go to this setting as soon as you reach 0 pitch in MW Econ Cruise. All step climbs (if any) will be in LW Econ Cruise.
So the routine is:
Using Standard Cruise Power HW Econ Cruise Power after leveling off, wait for 0 pitch, climb 2000 ft, repeat as desired. At maximum altitude either keep HW Econ Cruise Power or go to MW Econ Cruise Power. Plan 2940 PPH
Using Standard Long Range Cruise Power HW Econ Cruise Power after leveling off, wait for 0 pitch, go to MW Econ Cruise Power. At 0 pitch climb 2000 ft, repeat as desired. At maximum altitude either keep MW Econ Cruise Power or go to LW Econ Cruise Power. Plan 2720 PPH
Using Long Range Cruise Power HW Econ Cruise Power after leveling off, wait for 0 pitch, go to MW Econ Cruise Power. Wait for 0 pitch, go to LW Econ Cruise Power. At 0 pitch climb 2000 ft, repeat as desired. Plan 2600 PPH
Hope this helps,
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Post by blueaircraft on Jul 17, 2023 17:49:39 GMT -5
Thanks Tom I think I did everything relatively correct apart from step climbing. Always something to learn flying these old birds Regards Andrew
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