Friday, January 23, 2009

Did Amelia Earhart attempt to return to Rabaul after failing to locate Howland Island?

Map shoing the distance from Lae to Howland Island
Taking off from Lae in July 1937

Amelia Earhart and Fred Noonan
By MIKE FEENEY in AeroHub
Zillions of words have been written about Amelia and Fred’s last flight; much of it rather ‘imaginative’, to put it delicately. (I do not tell a porky when I say that I found a ‘Star Trek” site that said that they had been abducted from the cockpit by some aliens.) I do not wish to add too much to the story, but an aircraft engineer who used to be with Air Nuigini, has a theory which is explained below. I noted some aspects of David’s views which I suspect could do with some examination. If anyone knows where he currently is, would you mind giving him my regards and forwarding this on?
Below is an article from a recent issue of Papua New Guinea’s “The National” newspaper. The ‘Wings over Kansas’ link further down within the text is well worth opening but is a lengthy read.Whilst I have a very open mind, my feeling is still that Amelia and Fred got to somewhere far east out into the Pacific and in the general vicinity of tiny Howland Island (2,000 by 600 metres) and either ran out of fuel searching along a sun-line for Howland Island, or force-landed/ditched somewhere in the region; probably back in the Gilberts.
It seems highly improbable that they would have had enough fuel to return to New Britain unless they had turned back well before nearing their intended destination. But let’s crunch a few numbers and see.
Their aircraft was the L-10E variant with the larger Pratt & Whitney R-1340-49 ‘Wasp” engines. These produced 550 bhp when on the fuel they were using. I estimate the basic operating weight of the aircraft, with crew, oil, the weight of the extra tanks and various items of personal and survival gear, as about 7,000 lbs. The fuel load of 920 Imp. gallons weighed 6,624 lbs. Therefore the take-off weight out of Lae was about 13,600 lbs. This was some 3,000 lbs above the L-10E’s standard max. weight. An overload of about 27%.They departed Lae at midnight GMT. That was 10.00 hrs at Lae in order for Fred to take some three-star fixes before dawn the next morning. Now to fuel consumption.
Given the weight and the tropical temperatures of an average of 15-18 degrees above ISA, I estimate that the initial minimum power setting must have been at 80% during the long cruise-climb needed to hold the cylinder-head and oil temperatures within limits. Then progressively I am guessing that Amelia would have reduced power every hour or so until, near the end of the flight, the settings would have been about 40%. So the mean outbound power setting was something like 60%. 60% of the available 1,100 bhp = 660 bhp. I assume Amelia had expertise in manual mixture leaning procedures (she had had briefings and information from Lockheed’s famed “Kelly” Johnson) so my estimate of their average Specific Fuel Consumption (SFC), allowing for the long heavy slow climb with mixture somewhat on the rich side for cooling, is 0.45 lbs per bhp per hour. Being a SFC figure, this would not have changed significantly during most of the flight, no matter what the altitude. So we can now be reasonably sure that the average fuel-flow of the aircraft was pretty close to: 660 bhp x 0.45 = 297 lbs per hour = 41.25 Imp. gallons per hour…about 20 gph per engine. I know those engines and this figure seems sensible when the engines are operated by someone with expertise and finesse.
So we can now estimate that, given all of the above, the endurance of the aircraft was: 920 divided by 41.25 = 22.3 hours. When the aircraft was very light, this could be stretched even further by using extreme measures; reduce the rpm to the limits of the governor and set manifold-pressure to achieve whatever indicated airspeed was appropriate. About 1.7 times Vs for range or about 1.3 or 1.4 Vs for endurance. I believe we can work on a figure of about 23 hours to fuel exhaustion.As to the cruise speeds used, this is my view. The L-10E’s max. cruise true airspeed within the 7,000 - 12,000 feet altitude band is about 150 knots. But that is at normal weights and at ISA temps. I am fairly sure that, at the overload weights, albeit reducing, and at the air temperatures in the region and considering that they were flying to optimise range over a very long sector, that their cruise-climb speed would have been about 110 - 115 knots true airspeed and their true airspeed on cruise approx. 125 knots from a few hours into the cruise phase, slowly creeping up to perhaps 135. This also tends to tie in with their ground-speed outbound with a 15 knot headwind.
David Billings has said that the range of the aircraft was “4,000 miles”. That is 3,470 nautical miles. I consider he may be mistaken as, with 23 hours of fuel, and even assuming a cruise true airspeed speed of, say, 140 knots, the maximum air- range could not possibly exceed 3,220 nm. (3,700 statute miles). Those of you who have flown grossly overloaded aircraft, as I have, will know just how much performance is degraded; particularly climb and airspeed. I personally consider that the range of their aircraft for that flight was about 3,000 nautical miles tops!
David also said that after 14 hours they had burnt only 577 US gallons. That is 480 Imp. gallons which is only 34.3 gph; that is 17.14 Imp. gph. per engine. Given the climb and overload weight, that is improbable. At that sort of power percentage, at the high weight, I doubt the aircraft would even maintain level flight.
So let us now look at the route map. The great-circle distance is 2,220 nautical miles. Howland is located at 00.48′28″ N 176.37′06″ W. Lae is about 7 degrees south so there is little difference between the great-circle and the rhumb-line tracks. After take-off, they planned to track along the mainland coast and then abeam the south coast of New Britain. Then over Buka Island at the north end of Bougainville. They gave a position report passing Nukumanu Island and then it was towards the long Gilberts group which has a very large number of islands, most low-lying. As you can see, Howland is quite a few hours further on and is about 1,670 nm south-west of Honolulu. I am not going to go into why they could not locate it. There are numerous theories. But what we are considering is David’s belief that they could have tried to make it back to Rabaul which is at the eastern end of New Britain. You can see it is much closer than Lae.
At an average ground-speed of 120 knots, their time to the Howland longitude would have been about 18.5 hours; not allowing for weather diversions. (which they did make) 18.5 x 40 gallons per hour = 740 Imp. gallons. This would have left them with 920 - 740 = 180 Imp. gallons for search and/or diversion. Now at a very light weight, they could have used emergency low rpm settings and best-range airspeed to produce perhaps 30 gallons per hour and 110 knots true airspeed = 6 hours x 110 = 660 nautical miles to dry tanks. If heading back to the Gilberts with a 15 knot tail-wind component, their range would have been about 6 x 125 = 750 nm. That is hugely short of the fuel needed to get them back all the way to Rabaul.
One has only to sit back and consider the meridians on the map. At this latitude 5 degrees = 300 nm. From Howland (just eye-ball estimates) it is 500 nm back to the Gilberts. It is a further 900 to Honiara in the Solomons where, I think, there was some sort of airfield. Or about 900 from the Gilberts to Nukumanu Island. And from those two places, close to 500 nm to Rabaul.So, without going into a range of possible PNR calculations (I say chaps, this is your chance to dig out your ancient Jepp. “prayer-wheels” and enjoy a few jolly calculations like we did in ye olde times), one can readily see that Amelia and Fred would have had to have made a decision to return to New Guinea or divert to somewhere for an emergency landing long before they got to the longitude of the horrible little Howland Island.
Actually, I have long thought that they should have gone via Fiji… a lot longer, but far safer. I have also believed that they should have remained in Lae until they had sorted out their H.F. comm. set and their L.F. Direction-Finder problem…..Ah! What might have been…..
Just some final musings. If the engine found by the Australian Army patrol was a single-row, ungeared Pratt & Whitney R-1340 fitted with a two-blade propeller, then that would be compelling evidence that the aircraft could well be a Lockheed L-10E Electra. There were few that were fitted with that engine. I can recall no twin-engined wartime aircraft types, with that type of engine, that operated in that area. The RAAF Rabaul-based Wirraways used the geared version of the R-1340 with three-blade props. The two civil Lockheed L-10As that Guinea Airways operated out of Lae were flown to Australia when the Japanese invaded. It is remotely possible that the machine could have been a Lockheed Hudson; but they used Wright Cyclones. Anyway, the story still makes for absorbing reading. I have attached an old photograph of the aircraft on take-off from Lae. It was hugely overloaded with fuel (a staggering 1,100 US gallons) and used virtually all of the runway. Eyewitnesses reported that, after lift-off, it sank to near sea level with its props creating two lines of disturbance on the calm surface of the Huon Gulf. I would imagine that the wing-tip vortices would also have been creating some disturbance! The aircraft was last seen by the Lae people as it took up heading and flew at low-level until out of sight. The other photograph is one I have always rather liked. Just a simple one of Amelia and Fred discussing something together.
An idea that I just thought of. The Japanese captured various civil types during their invasions, and used them. Is it possible that the mystery aircraft could be one of those? Something to mull over perhaps?Please do feel free to contact me and “shoot me down” over my above thoughts and calculations. I dashed off this item in a hurry as the PNG news item seems to be running hot around the internet. I have received the Earhart news from eight people so far.
PS: Since writing the above, I have heard from David Billings and we have been exchanging E-mails. I have since been crunching many numbers again. Briefly, David asked me if I thought they might have made it to Rabaul if they had turned back 260 nm short of Howland with 250 Imp. gallons remaining. Withour weather diversions, they would have had 1,600 nm to fly. After a lot of sums, I advised him that, if they used 30% power, reduced rpm to about 14 or 1,500 rpm, used extreme mixture leaning and could maintain height on 330 bhp total, burning just 9 Imp. gph per engine, and achieve 90 knots indicated airspeed at 5,000 feet, and had an average tailwind component of 25 knots; then they might just have made it…but there are a lot of “Ifs” there.Have any of you older chaps flown an L-10? Or perhaps the similar Beech 18?This is an ongoing study which may continue to be of interest.
Earhart’s plane found at last?
THE discovery of the wreckage of an aircraft in the Ip River in East Pomio, East New Britain province last week, has generated renewed speculation that it could be the aircraft belonging to famed American aviatrix, Amelia Earhart.What makes this particular discovery significant is the fact that an Australian aircraft engineer, who has been involved since 1994 in a project to locate Ms Earhart’s Lockheed Electra 10E, had pinpointed the location where the wreckage was found as the place where he believed Ms Earhart’s plane went down.An entry on the free internet encyclopaedia Wikipedia (http://en.wikipedia.org/wiki/Amelia_Earhart#Departure_from_Lae) says the engineer, former Air Niugini employee David Billings, asserts that a map marked with notations consistent with Ms Earhart’s engine model number and her airframe’s construction number, was seen briefly by Australian soldiers during World War II.Mr Billings’ theory originates from the WWII Australian patrol stationed on East New Britain and indicates a crash site 64km (40 miles) southwest of Rabaul, which is only a few kilometres away from where the wreckage was found last week.Mr Billings speculated that Ms Earhart turned back from her intended destination of Howland Island in the Pacific Ocean after unsuccessfully trying to rendezvous with an American warship, and tried to reach Rabaul for fuel.Mr Billings and his team had made 10 attempts to locate the wreckage. His theory is contained in an exhaustive article on an American aviation website
http://www.wingsoverkansas.com/earhart/article.asp?id=850
detailing the reasons for his conclusion that the wreckage spotted by the Diggers on April 17, 1945, belonged to Ms Earhart.Ms Earhart and her navigator, Fred Noonan, took off from Lae on July 2, 1937, in the heavily loaded Electra for Howland Island 4,113km (2,556 miles) away. To date, their disappearance had remained an enduring mystery.A brief report in Monday’s The National prompted one reader from Australia to write in to suggest that the wreckage could belong to Ms Earhart’s Electra.Further research on the internet revealed Mr Billings’ theory pinpointing the area 64km southwest of Rabaul where the Diggers spotted the wreckage in 1945.A community leader from the Kalip ward in East Pomio, Isidor Vote, said last week that the aircraft was discovered by a group of youths in the Ip River in the bushes of East Pomio.Local villagers believed the aircraft might have been shot down during World War I between 1913 and 1914, and even suggested it was being flown by a female American pilot. It is not known what their theory is based on.Mr Vote said the wreckage had the serial number 06751 on one of its body parts that had remained intact all these years, and parts of one of its wings had dents on it.Mr Vote wanted Government authorities to visit the site and inspect the aircraft in order to get more information.He said it would serve as a record for the War Museum in Kokopo.If the find proves to indeed be Ms Earhart’s Electra, it will have far more significance and could prompt an international media frenzy in the Pomio area.

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