Bonjour, Oppo

"ttyymmnn" (ttyymmnn) 03/04/2020 at 08:45 • Filed to: good morning oppo, Planelopnik, wingspan

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There’s a lot to look at in this photo of an Air France L-749 Lockheed Constellation (F-BAZH, “Rue de la Paix”) being serviced at Paris Orly in the late 50s. Of particular interest to me, aside from the awesome whitewall tires on the fuel bowser, is the lowered Speedpak freight container underneath the fuselage.

This particular aircraft !!!error: Indecipherable SUB-paragraph formatting!!! in 1950, where it flew between points in Europe and to New York City. In 1960, it was sold to Royal Air Maroc, the national carrier of Morocco, sold again and converted to a freighter, changed hands a few more times, including US ownership, and ended up as scrap in 1973.

TheRealBicycleBuck > ttyymmnn 03/04/2020 at 09:03

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Belly cargo pods are the best! The first step is getting an airplane with enough useful load capacity to carry the weight of the pod and anything you put in it.

ttyymmnn > TheRealBicycleBuck 03/04/2020 at 09:40

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It helps when you have long legs

SBA Thanks You For All The Fish > ttyymmnn 03/04/2020 at 09:53

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Sometimes the pods DON’T carry luggage and air freight...

Rusty Vandura - www.tinyurl.com/keepoppo > ttyymmnn 03/04/2020 at 11:10

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Of interest to me would be what’s inside the fuel carrier. High-octane aviation gasoline, and lots of it , which as far as I know, is very difficult to obtain nowadays.

ttyymmnn > Rusty Vandura - www.tinyurl.com/keepoppo 03/04/2020 at 11:20

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From the Wikipedia:

Early versions of the R-3350 had carburetors, though the poorly-designed elbow entrance to the supercharger led to serious problems with fuel/air distribution. Near the end of WWII, the system was changed to use gasoline direct injection where fuel was injected directly into the combustion chamber. This improved engine reliability. After the war the engine was redesigned and became popular for large aircraft, notably the Lockheed Constellation and Douglas DC-7 .

Following the war the Turbo-Compound system was developed to deliver better fuel efficiency. In these versions, three power-recovery turbines (PRT) were inserted into the exhaust piping of each group of six cylinders, and geared to the engine crankshaft by fluid couplings to deliver more power. The PRTs recovered about 20% of the exhaust energy (around 450 horsepower (340 kW)) that would have otherwise been wasted, but reduced engine reliability (Mechanics tended to call them Parts Recovery Turbines, since increased exhaust heat meant a return of the old habit of the engine eating exhaust valves). The fuel burn for the PRT-equipped aircraft was nearly the same as the older Pratt and Whitney R-2800, while producing more useful horsepower. Effective 15 October 1957 a DA-3/DA-4 engine cost $88,200.

By this point reliability had improved with the mean time between overhauls at 3,500 hours and specific fuel consumption in the order of 0.4 lb/hp/hour (243 g/kWh, giving it a 34% fuel efficiency). Engines in use now are limited to 52 inHg (180 kPa) manifold pressure , being 2,880 horsepower (2,150 kW) with 100/130 octane fuel (or 100LL) instead of the 59.5 inHg (201 kPa) and 3,400 horsepower (2,500 kW) possible with 115/145, or better, octane fuels, which are no longer available since many such formulations are toxic.

Rusty Vandura - www.tinyurl.com/keepoppo > ttyymmnn 03/04/2020 at 11:31

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I learnt from Leo Swanson -- remember him? Metal Shop teacher at Maury -- that octane is gasoline’s resistance to detonating without a spark while under pressure. The higher the number, the more compression you can have. No more energy per unit volume of fuel, just that I suppose you can cram in more of it and make more power than you might with a lower octane number.

Ash78, voting early and often > ttyymmnn 03/04/2020 at 13:17

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London to SF, nonstop, in 23+ hours. That record always sticks out for me.

And a much lower carbon footprint than a jet going twice as fast, but we didn’t care about that at the time jets were invented.

I know I’ve said it before, but I wonder if we were starting from scratch with air travel, whether slow, comfortable, fuel efficient piston aircraft would have an advantage in today’s environment. Onboard wifi, large seats, etc. The lower fuel burn could be passed along as savings. But you’d still probably have huge costs of backup crews on really long flights.

And of course you’re limited in the total size of the aircraft. But an airline version of a B-36 would be epic.

gmporschenut also a fan of hondas > Ash78, voting early and often 03/04/2020 at 21:51

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I’ve always wondered the same on shorter 2-3 hour routes. i remember when fuel prices were spiking there was discussion why airbus went forward with the a400 vs a jet like the c17