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Flight Modeling - Lae to Howland Island

Key factors involved in re-navigating this flight

For this research, prior to AE’s 0718 GMT in-flight position report, climb speeds were determined from L487 and Kelly Johnson power setting recommendations, engine operating limitations, climb speed specifications, with consideration of climb rate as reported by Pellegreno.

From AE’s 0718 GMT in-flight position report, to Howland Island, the re-calculated true airspeed was determined by setting power in accordance with L48744 and Kelly Johnson recommendations45, with reference to direct evidence from previous flight profiles, statistical reference, and behavior where AE included specifics about power setting and speed, in flight notes. Lockheed and Pratt-Whitney data were also considered.

This technique produced en route speeds after 0718 GMT, of 138 knots true air speed, or 158.8 mph.

Applying the 23 knots, or 26.5 mph, headwind component, produced 116 knots ground speed, or 132.3 mph ground speed, after the 0718 GMT position, which was held until the perceived descent point to Howland Island at approximately 80 statute miles per Kelly Johnson, Paul Mantz (OAK-HNL) and Fred Noonan recommendations.

Our result of 132.3 mph ground speed, from the 0718 GMT position to Howland Island, is only 1.7 mph (1.2%) less than Long’s overall mission average ground speed. Our result of 158.8 mph true air speed is also 1.7 mph (1.1%) less than Long’s overall average true air speed.

These are considered valid performance numbers, and when combined in a discrete and stepwise analysis, the modeling technique provides a more accurate profile.

Despite flying a Lockheed Model 10A aircraft with smaller engines, less weight and likely a lower drag profile, Pellegreno46 routinely observed ground speeds of 133-135 mph during a Commemoration Flight, indicating that computed speeds are in the range of reasonable performance.

Pellegreno’s aircraft has effectively the same horsepower-to-weight ratio as AE’s Electra 10E.

Long assumed a constant overall true air speed of 160.5 mph47, in the presence of a constant headwind component of 26.5 mph, producing an overall mission average ground speed of 134 mph.

Long’s approach of averaging distance and time was updated in our research using a discrete approach, a stepwise analysis at each waypoint, facilitated by software.

Using flight planning and analysis software to model the climb, cruise, descent performance and wind effects, can produce a more accurate overall mission analysis. The software enabled modeling three flight paths, sensitivity analyses from headwind speed and direction modifications, and examination of route timing and the terminal EON position.

Further corroboration of these results is found in L487 48 that recommended flying at 155 mph indicated air speed at 2,000 feet, 145 mph indicated air speed at 4,000 feet, and 135 mph indicated air speed at 8,000 feet. This profile was apparently not flown, as it was pre-empted by later Kelly Johnson profile recommendations, which appear to have been executed and adhered to on many World Flight segments, including the Lae to Howland Island segment. The 8,000 feet speed specification is very near what AE likely flew.

The later Kelly Johnson recommendations specified flying at 8,000 feet, and under conditions that likely existed during AE’s flight, are equivalent to 155.4 mph true air speed. Kelly Johnson Telegrams49 indicated power settings and speeds, showing that after 0718 GMT, a target speed would be 133-158 mph true air speed.

This data and resultant recommendations were based on analytic aerodynamic calculations including wind tunnel testing, and actual flight test data from AE’s aircraft.

L48750 provided values for flight at sea level, with no altitude adjustments, and recommended flying 150 mph true air speed in still air, and with a 20 mph headwind, flying 154 mph true air speed.

Table 2, from 0718 GMT to approximately 1830 GMT, compares cruise performance in statute miles per hour (MPH), for this specific cruise segment.

Table 2 - Comparative Speed CalculationsAE adhered remarkably close to these recommendations. These speeds are highly corroborated. (Footnote 51 next to Long Research in table 2)

The MSI and modeling process forms a corroborating body of evidence of the likely mission flight performance actually achieved on the Lae to Howland Island mission segment, in terms of speed, fuel consumption, position and time. MSI incorporated a broader range of corroborated data sources:

All AE in-flight reports

AE historical performance data

The Nauru Island weather observation of upper altitude winds

Data used by Long

The L487 report aerodynamic data

Kelly Johnson recommendations

Swenson and Culick’s analysis

Our independent analysis for validation of previous work

Lockheed Electra Operating Manuals

Pratt-Whitney engine operating data specific to AE’s engines

Using this MSI blending process we calculate performance used in our aircraft modeling and flight planning process, as follows:

Indicated Air Speed within 2.3% of L487 and 0.8% of Long

True Air Speed within 2.2% of L487 and 1.1% of Long

Ground Speed within 1.2% of L487 and 1.3% of Long

This methodology directly affects speed, time, fuel consumption, and most important, final position. Except for lateral navigation track errors or deviations from a planned path, speed and fuel consumption are the most fundamental parameters in locating the Electra, and worthy of close scrutiny.

Improved Accuracy
Modern methods yielding 2% improvements in a solution represent approximately 50nm in a final EON point on a Lae to Howland Island segment.

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