Post by volkerboehme on Jun 13, 2010 2:14:10 GMT -5
The Lockheed L-1649A Starliner was one of the most complicated propliners ever created. In was the last of the great dinosaurs weighing in a full 15,000lbs heavier than the Boeing 377 or Douglas DC-7C. To allow it to fly at all it needed a wing of exceptional span and aspect ratio. The spar of that extended wing was weak. It could depart with a great deal of fuel aboard, enough for San Francisco direct London which is around 4700 miles, but it could not land with significant fuel remaining. The bending moment on the main spar at the moment of touchdown was too great.
Whenever we fly the L-1649A fuel planning is essential. It has the potential to depart at 160,000lbs, yet it must land at no more than 123,000lbs. Of course if we fly KSFO - EGLL we will use over 55,000lbs of fuel and we will be down to around 105,000lbs before we land, but shorter distances require careful planning. The TWA London service began in Los Angeles. We cannot depart Los Angeles at 160,000lbs since we must be down to 123,000lbs when we begin the approach to San Francisco.
KLAX - KSFO is only 300 miles. We must fuel plan accordingly. Fuel planning is explained in detail within Part 6 of the Propliner Tutorial available from www.calclassic.com/tutorials. Our holding reserve will be 45 minutes, our diversion reserve will be 45 minutes, and our headwind reserve will be 15%. To discover the route fuel required we consult the L-1649A handling notes;
***********************************
Normal Cruise:
''''
MAP = 37 inches
RPM = 2200
''''
PLAN 3200 PPH
Note: - Yields 290 KTAS at FL220
When WEIGHT <= 123,000lbs
Begin ECON CRUISE
***********************************
On any short haul flight we intend to land at 123,000lbs so we will never call for econ cruise on a short haul flight. Normal cruise must be planned at 3200 PPH and 290 KTAS nil wind. The Propliner Tutorial explains why we will never reach 290 KTAS and why that is irrelevant.
The route fuel is 300 miles @ 290 KTAS @ 3200 PPH = 3300lbs
Headwind reserve = 3300 * 15% = 500lbs
Holding and diversion reserve (0.75 + 0.75) * 3200 = 4800lbs
So we will load only 8600lbs of AVGAS for KLAX - KSFO regardless of our payload.
How much 'payload' can we carry?
First we must remember that in MSFS the crew are part of the 'payload', though not in real life.
Despite expectation our maximum payload does not depend on maximum take off weight. It depends on maximum landing weight; which is a function of of structural strength, not power available.
When we land an airliner we still have an empty aeroplane plus all the payload, but we must remember that we also intend to land with all of our reserve fuel intact. We may, or may not, use our reserve fuel, and we do not intend to dump it if we don't!
We have just calculated our reserve fuel and so now we must consult the aircraft.cfg to discover our empty weight and maximum landing weight
empty_weight=94700 ;APS inc galley, toilets, catering etc
MLW = 123000
Max payload = MLW - empty_weight - reserve fuel
So for KLAX - KSFO max safe payload = 123,000 - 94,700 - 5,300 = 23,000 lbs
Or to put it another way the heaviest weight at which we can depart KLAX for KSFO is maximum landing weight plus route fuel which is only 3300lbs.
123,000 + 3,300 = 126,300lbs even though we have enough power to depart at 160,000lbs.
That surplus power will not protect the weak main spar during the shock of landing only an hour or so later when our weight must not exceed 123,000lbs.
Trips this short in a propliner always require very careful fuel planning or we will end the flight flying the approach at a dangerous weight. What makes the L-1649A special is the fact that it was designed to fly 4700 miles non stop and *any trip under 3300 miles is a short haul*. Since we will usually intend to fly less than 3300 miles (less than 11 hours) we must always conduct very careful fuel and payload planning before we fly the L1649A in FS9.
It should come as no surprise that it makes a huge difference to performance whether we depart KLAX with 8,600lbs of fuel for KSFO at a weight of 126,300lbs or with 59,000lbs of fuel for EGLL at a weight of 160,000lbs. However we must not climb to an altitude that we cannot sustain in normal cruise power after either departure. We must use the technique described in the handling notes to ensure that we do not climb above our operational ceiling, however light or heavy we depart.
***********************************
Climb Power:
Plan 3600 PPH
COWL FLAPS = CLIMB
MAP = 40 inches
RPM = 2500
VSI = 500
IAS will increase then decay
WHEN IAS DECAYS THROUGH 175 KIAS
Begin NORMAL CRUISE and step climb
see www.calclassic.com/tutorials
>>>>>>>>>>>>>>>>>>>>>>>>>>
*POLAR FLIGHTS ONLY*
Reaching FL150/160 (eastbound/westbound)
Begin ECON CRUISE and step climbs
***********************************
We see that 'Polar' flights such as San Francisco - London are a special case. Polar flights always depart at max gross and polar eastbound we must not climb above FL150. To fly 4700 miles with adequate reserves we must use no more than econ cruise power for cruising and econ cruise power will not support cruise above FL160 following a max gross departure.
On other flights we still apply 40/2500 and climb at 500 VSI, but then we must watch for IAS decay. When IAS decays to 175 KIAS we are approaching our operational ceiling in the current weather, at our current weight, (including any ice we have accumulated which is weighing us down and /or throttling the engines). We must level off and begin step climbs. On a non polar flight we will use normal cruise power. The Propliner Tutorial explains all of this in greater detail.
The last generation of dinosaurs were very powerful, but also fragile. The L-1649A has more than enough power to rip its own tail off in either warm or cold air. The greatest danger is cold air. The higher we fly the colder the air and the greater the risk of transonic shock. If the air is cold enough and we are light enough we can rip the tail off in normal cruise power. The drag safety limits must be observed with great care.
Fortunately the Starliner has a 'BARBER POLE' within its ASI; though in the L-1649A it is actually a red needle rather than a striped pole. Provided we never allow the IAS needle to reach the red structural failure needle we will not rip the tail off. The colder the air the lower our safety limit, but all we need to do is avoid ASI needle merger.
***********************************
Normal Cruise:
''''''''''''''
RPM = 2200
MAP = 37 inches
'''''''''
WARNING - AVOID Mno = M0.55
Use BARBER POLE see www.calclassic.com/tutorials
'''''''''
***********************************
Of course the situation is much more dangerous when we need to descend. Yet we must fly high and cold to maximise cruising velocity (TAS). Again all of this is explained in more detail in the Propliner Tutorial.
The R-3350 engines are very complex, very expensive to overhaul, and very fragile. After obstacle clearance we must not exceed 43 inches MAP, yet we must not apply less than 24 inches until we cross the destination boundary fence at Vref and we are about to flare, up to 22 hours later.
These engines are very prone to shock cooling. We can increase fuel flow quite quickly without fear, but we must reduce fuel flow *very* gradually when we intend to descend with (cooling) drag (IAS) potentially increasing.
****************************
Descent:
COWL FLAPS = CLOSED
REDUCE MAP in stages of 3 inches per minute
RPM = 2200
MIN 24 INCHES MAP *UNTIL AIRFIELD BOUNDARY*
****************************
If we have been cruising at 37 inches we can only retard the throttles to 34 inches at top of descent, then a minute later to 31, then a minute later to 28, then a minute later to 25 and a minute later to 24. Throughout that time we will normally be descending at the legal minimum of -500 VSI to avoid potential structural failure at M0.55. It takes five minutes to power down from 37 inches to 24 inches. We will descend only 2500 feet from cruising level in those five minutes to restrain Mach in the power dive. Only when we have powered down to 24 inches do we target -700 VSI.
We do not intend to use the speed brake to discard energy, but we may need to. If we throw away energy we accumulated with fuel burn we lose profit, but profit is less important than safety. Even if we use speed brake to increase VSI at target IAS we cannot reduce MAP (and fuel burn) any faster. Using speed brake to increase VSI at a target IAS does not prevent shock cooling of engines. Remember we cannot deploy speed brake > 234 KIAS anyway. This is not just a case of not extending the brake > 234 KIAS; we must not exceed 234 KIAS whilst it is deployed. That would rip the main gear off.
The L-1649A uses only its main gear legs as an air brake. Never use the gear lever for braking. The nosewheel will be ripped off.
Piston aero engines must be revved up, but powered down. When we need to increase thrust, (e.g. to step climb), we rev up and then we power up;
RPM = 2500
MAP = 40 inches
VSI = 500
but when we are climbing out after take off and reducing the load on the engines we power down,
MAP = 40 inches
RPM = 2500
VSI = 500
We must reduce our drag to 175 KIAS before we reach a holding fix or the initial approach fix. In the L-1649A we should reduce our profile drag to 140 KIAS and deploy FLAP 1 before we make any of the turns in a hold or an approach procedure.
FLAP 1 is 80% of the FLAP available!
After take off do not exceed a drag of 140 KIAS with FLAP deployed. This happens very quickly! Removing 80% flap may cause a heavy departure to sink hard. Be ready for it. We must restrain climb to achieve 140 KIAS quickly, then retract flap. We sustain a profile drag of 140 KIAS until we are above all obstacles in the departure. See www.calclassic.com/tutorials.
**********************************
METO Power: (Climb stage 1)
COWL FLAPS = 30%
MIXTURE = AUTO
MAP = 51 inches
RPM = 2650
140 KIAS
Above all obstacles
500 VSI
ACCELERATE = 170 KIAS
CALL for max or normal climb power
See www.calclassic.com/tutorials
***********************************
Max cruise and fast cruise are used only to battle headwinds. See www.calclassic.com/tutorials.
During the approach it is essential to reduce drag <= 140 KIAS with FLAP 1 deployed early. We must extend the gear before we reach the glideslope and we must reduce profile drag to 130 KIAS in the final descent (provided that does not require < 24 inches MAP). We must anyway extend FLAP 2 (full flap) at the right moment to achieve Vref at the destination boundary fence. Vref is 114 KIAS if we are at max landing weight. For calculation of Vref, Vr etc versus weight see www.calclassic.com/tutorials.
**************************************
Realism issues arising from potential panel conflicts
**************************************
FSAviator's flight dynamics require use of the co-bundled enhanced realism panel.cfg and gauges. Flight dynamics and panels are not mix and match.
WARNING: You MUST turn Automixture ON (in the FS2004 Aircraft/Realism menu)to have accurate mixture control.
FSAviator and Tom Gibson - May 2008
Whenever we fly the L-1649A fuel planning is essential. It has the potential to depart at 160,000lbs, yet it must land at no more than 123,000lbs. Of course if we fly KSFO - EGLL we will use over 55,000lbs of fuel and we will be down to around 105,000lbs before we land, but shorter distances require careful planning. The TWA London service began in Los Angeles. We cannot depart Los Angeles at 160,000lbs since we must be down to 123,000lbs when we begin the approach to San Francisco.
KLAX - KSFO is only 300 miles. We must fuel plan accordingly. Fuel planning is explained in detail within Part 6 of the Propliner Tutorial available from www.calclassic.com/tutorials. Our holding reserve will be 45 minutes, our diversion reserve will be 45 minutes, and our headwind reserve will be 15%. To discover the route fuel required we consult the L-1649A handling notes;
***********************************
Normal Cruise:
''''
MAP = 37 inches
RPM = 2200
''''
PLAN 3200 PPH
Note: - Yields 290 KTAS at FL220
When WEIGHT <= 123,000lbs
Begin ECON CRUISE
***********************************
On any short haul flight we intend to land at 123,000lbs so we will never call for econ cruise on a short haul flight. Normal cruise must be planned at 3200 PPH and 290 KTAS nil wind. The Propliner Tutorial explains why we will never reach 290 KTAS and why that is irrelevant.
The route fuel is 300 miles @ 290 KTAS @ 3200 PPH = 3300lbs
Headwind reserve = 3300 * 15% = 500lbs
Holding and diversion reserve (0.75 + 0.75) * 3200 = 4800lbs
So we will load only 8600lbs of AVGAS for KLAX - KSFO regardless of our payload.
How much 'payload' can we carry?
First we must remember that in MSFS the crew are part of the 'payload', though not in real life.
Despite expectation our maximum payload does not depend on maximum take off weight. It depends on maximum landing weight; which is a function of of structural strength, not power available.
When we land an airliner we still have an empty aeroplane plus all the payload, but we must remember that we also intend to land with all of our reserve fuel intact. We may, or may not, use our reserve fuel, and we do not intend to dump it if we don't!
We have just calculated our reserve fuel and so now we must consult the aircraft.cfg to discover our empty weight and maximum landing weight
empty_weight=94700 ;APS inc galley, toilets, catering etc
MLW = 123000
Max payload = MLW - empty_weight - reserve fuel
So for KLAX - KSFO max safe payload = 123,000 - 94,700 - 5,300 = 23,000 lbs
Or to put it another way the heaviest weight at which we can depart KLAX for KSFO is maximum landing weight plus route fuel which is only 3300lbs.
123,000 + 3,300 = 126,300lbs even though we have enough power to depart at 160,000lbs.
That surplus power will not protect the weak main spar during the shock of landing only an hour or so later when our weight must not exceed 123,000lbs.
Trips this short in a propliner always require very careful fuel planning or we will end the flight flying the approach at a dangerous weight. What makes the L-1649A special is the fact that it was designed to fly 4700 miles non stop and *any trip under 3300 miles is a short haul*. Since we will usually intend to fly less than 3300 miles (less than 11 hours) we must always conduct very careful fuel and payload planning before we fly the L1649A in FS9.
It should come as no surprise that it makes a huge difference to performance whether we depart KLAX with 8,600lbs of fuel for KSFO at a weight of 126,300lbs or with 59,000lbs of fuel for EGLL at a weight of 160,000lbs. However we must not climb to an altitude that we cannot sustain in normal cruise power after either departure. We must use the technique described in the handling notes to ensure that we do not climb above our operational ceiling, however light or heavy we depart.
***********************************
Climb Power:
Plan 3600 PPH
COWL FLAPS = CLIMB
MAP = 40 inches
RPM = 2500
VSI = 500
IAS will increase then decay
WHEN IAS DECAYS THROUGH 175 KIAS
Begin NORMAL CRUISE and step climb
see www.calclassic.com/tutorials
>>>>>>>>>>>>>>>>>>>>>>>>>>
*POLAR FLIGHTS ONLY*
Reaching FL150/160 (eastbound/westbound)
Begin ECON CRUISE and step climbs
***********************************
We see that 'Polar' flights such as San Francisco - London are a special case. Polar flights always depart at max gross and polar eastbound we must not climb above FL150. To fly 4700 miles with adequate reserves we must use no more than econ cruise power for cruising and econ cruise power will not support cruise above FL160 following a max gross departure.
On other flights we still apply 40/2500 and climb at 500 VSI, but then we must watch for IAS decay. When IAS decays to 175 KIAS we are approaching our operational ceiling in the current weather, at our current weight, (including any ice we have accumulated which is weighing us down and /or throttling the engines). We must level off and begin step climbs. On a non polar flight we will use normal cruise power. The Propliner Tutorial explains all of this in greater detail.
The last generation of dinosaurs were very powerful, but also fragile. The L-1649A has more than enough power to rip its own tail off in either warm or cold air. The greatest danger is cold air. The higher we fly the colder the air and the greater the risk of transonic shock. If the air is cold enough and we are light enough we can rip the tail off in normal cruise power. The drag safety limits must be observed with great care.
Fortunately the Starliner has a 'BARBER POLE' within its ASI; though in the L-1649A it is actually a red needle rather than a striped pole. Provided we never allow the IAS needle to reach the red structural failure needle we will not rip the tail off. The colder the air the lower our safety limit, but all we need to do is avoid ASI needle merger.
***********************************
Normal Cruise:
''''''''''''''
RPM = 2200
MAP = 37 inches
'''''''''
WARNING - AVOID Mno = M0.55
Use BARBER POLE see www.calclassic.com/tutorials
'''''''''
***********************************
Of course the situation is much more dangerous when we need to descend. Yet we must fly high and cold to maximise cruising velocity (TAS). Again all of this is explained in more detail in the Propliner Tutorial.
The R-3350 engines are very complex, very expensive to overhaul, and very fragile. After obstacle clearance we must not exceed 43 inches MAP, yet we must not apply less than 24 inches until we cross the destination boundary fence at Vref and we are about to flare, up to 22 hours later.
These engines are very prone to shock cooling. We can increase fuel flow quite quickly without fear, but we must reduce fuel flow *very* gradually when we intend to descend with (cooling) drag (IAS) potentially increasing.
****************************
Descent:
COWL FLAPS = CLOSED
REDUCE MAP in stages of 3 inches per minute
RPM = 2200
MIN 24 INCHES MAP *UNTIL AIRFIELD BOUNDARY*
****************************
If we have been cruising at 37 inches we can only retard the throttles to 34 inches at top of descent, then a minute later to 31, then a minute later to 28, then a minute later to 25 and a minute later to 24. Throughout that time we will normally be descending at the legal minimum of -500 VSI to avoid potential structural failure at M0.55. It takes five minutes to power down from 37 inches to 24 inches. We will descend only 2500 feet from cruising level in those five minutes to restrain Mach in the power dive. Only when we have powered down to 24 inches do we target -700 VSI.
We do not intend to use the speed brake to discard energy, but we may need to. If we throw away energy we accumulated with fuel burn we lose profit, but profit is less important than safety. Even if we use speed brake to increase VSI at target IAS we cannot reduce MAP (and fuel burn) any faster. Using speed brake to increase VSI at a target IAS does not prevent shock cooling of engines. Remember we cannot deploy speed brake > 234 KIAS anyway. This is not just a case of not extending the brake > 234 KIAS; we must not exceed 234 KIAS whilst it is deployed. That would rip the main gear off.
The L-1649A uses only its main gear legs as an air brake. Never use the gear lever for braking. The nosewheel will be ripped off.
Piston aero engines must be revved up, but powered down. When we need to increase thrust, (e.g. to step climb), we rev up and then we power up;
RPM = 2500
MAP = 40 inches
VSI = 500
but when we are climbing out after take off and reducing the load on the engines we power down,
MAP = 40 inches
RPM = 2500
VSI = 500
We must reduce our drag to 175 KIAS before we reach a holding fix or the initial approach fix. In the L-1649A we should reduce our profile drag to 140 KIAS and deploy FLAP 1 before we make any of the turns in a hold or an approach procedure.
FLAP 1 is 80% of the FLAP available!
After take off do not exceed a drag of 140 KIAS with FLAP deployed. This happens very quickly! Removing 80% flap may cause a heavy departure to sink hard. Be ready for it. We must restrain climb to achieve 140 KIAS quickly, then retract flap. We sustain a profile drag of 140 KIAS until we are above all obstacles in the departure. See www.calclassic.com/tutorials.
**********************************
METO Power: (Climb stage 1)
COWL FLAPS = 30%
MIXTURE = AUTO
MAP = 51 inches
RPM = 2650
140 KIAS
Above all obstacles
500 VSI
ACCELERATE = 170 KIAS
CALL for max or normal climb power
See www.calclassic.com/tutorials
***********************************
Max cruise and fast cruise are used only to battle headwinds. See www.calclassic.com/tutorials.
During the approach it is essential to reduce drag <= 140 KIAS with FLAP 1 deployed early. We must extend the gear before we reach the glideslope and we must reduce profile drag to 130 KIAS in the final descent (provided that does not require < 24 inches MAP). We must anyway extend FLAP 2 (full flap) at the right moment to achieve Vref at the destination boundary fence. Vref is 114 KIAS if we are at max landing weight. For calculation of Vref, Vr etc versus weight see www.calclassic.com/tutorials.
**************************************
Realism issues arising from potential panel conflicts
**************************************
FSAviator's flight dynamics require use of the co-bundled enhanced realism panel.cfg and gauges. Flight dynamics and panels are not mix and match.
WARNING: You MUST turn Automixture ON (in the FS2004 Aircraft/Realism menu)to have accurate mixture control.
FSAviator and Tom Gibson - May 2008
