It takes a stretch to suggest that it was the plane described in the article rather than the Jet Age that marked the transition to what could be described as a "modern airliner".
This is a propellor airliner, from a generation before the Comet. Though even then it's unclear what makes it the first modern airliner; if you're defining that as "metal, purpose-designed, more than 10 passengers", as they seem to be, the similar Junkers Ju 52 was around earlier (this is mostly remembered as a military aircraft now, but started life as a civilian airliner).
I feel like you and the article are talking about different things since the 247 was a prop plane in 1933, and the precursor to the DC-1, 2, and 3. The DC-3 being of course one of the most successful planes in history, and is still in service as an airliner in some places. How many comets are still flying on regular schedules?
Debates about what counts as "modern" are always subjective, but the DC-3's longevity owes a lot more to its indestructibility, its convertibility to non-airliner uses, and and relative lack of interest on the part of modern airframers in newer small, slow models optimised for bouncy landings than it having much in common with what most people think of as a "modern" airliner.
Similarly, the lack of first generation jets flying today has a lot more to do with metal fatigue and the maintenance requirements that resulted than the notion that small slow planes with less to go wrong with them are a more modern design. Suspect there are more retro rotary phones in service than first generation iPhones today for similar reason, but I'm not sure that weakens the iPhone's claim to be the first modern mobile phone.
Basically both Boeing and Douglas (and others) had various dual-prop planes that could be used for passenger service in the early 30s timeframe--of which the DC-3 is the best-known (and came a couple years after the plane in the article).
But were these modern airliners and which was the first in that class. <shrug>
Plus of course a few takes on all metal monoplanes with multiple engines and multiple rows of passenger seats in the 1920s, if those are the criteria for modernity...
Think there's a decent case for the Vickers Viscount in the early 1950s too, as the first airliner with a modern turboprop engine type, with speed and range and passenger experience (big pressurised cabin) comparable to small airliners still being built, unlike the 247 or DC-3.
> Similarly, the lack of first generation jets flying today has a lot more to do with metal fatigue and the maintenance requirements
Don't forget engine efficiency. Early jets engines were extremely fuel hungry, and even today in the span of a decade engine efficiency has drastically improved.
True, consistent fuel efficiency is a huge part of the limited design life of modern aircraft, and why it makes sense for airliners to pay for brand new aircraft to replace perfectly adequate 10 year old aircraft on competitive routes. And the fuel economy of the Comet and 707 was awful. But to my knowledge the DC-3 fuel economy doesn't compare favourably on a passenger-km or tonne km basis with later generation jet aircraft that have been retired
Difference is you can keep an ancient DC-3 around for occasional use with relatively basic maintenance, whereas a second generation jet or turboprop comes with service and life-limited parts requirements to make it considered airworthy that would cost more than the aircraft is worth...
The Comet wasn't particularly successful (at least in part because of its fundamental design flaw) - but the military version - the Nimrod - flew until 2011.
Wait until you learn that the "early modern" period started in 1400 or so.
The point being that the term modern is most certainly subjective and definitely has usage that is different from "contemporary" even though the latter is how people often read it.
Qualified disagreement -- it's all about the word modern.
The Comet airframe was inherently limited by the decision to embed the engines -- de Havilland Ghost turbojets -- in the wing roots. Obviously this wwas great for drag reduction, but it made it difficult to modify the design to accommodate other, more efficient/economical engines. In the end, the attempt to refit the last Comet-descended airframes, the RAF's Nimrod MRA2's to MRA4 spec with Rolls-Royce BR700 turbofans in the 1990s/2000s failed due to spiraling prices because the higher diameter turbofans required substantial redesign/reworking of the wing roots. More here:
Having the engines hung on pods below the wing (or alongside the fuselage) makes them inherently easier to service and easier to upgrade (although problems can emerge if you push it too far, as witness the Boeing 737 MAX crashes).
This isn't to dismiss the Comet completely: it was a pioneering design, broke ground, and was the first trans-Atlantic jet airliner in service. But it had design flaws beyond the infamous metal fatigue problem.
I think if the Comet is ruled out on the ground of design flaws, Boeing's 707 (only slightly after it, and the first commercially successful jet) is a much better "modern airliner" candidate than the 247 since there are still bestselling airliners rolling off the production today with cabins based on the 707's, which cruise at a similar speed over similar distances using a much more advanced development of its jet engine technology. (The 707 is also derived from the same experimental platform as the KC-135)
I don't see engine retrofits as being disqualifying though, as modern engines seldom retrofit to older wings even if the original engines were podded (the MAX wings were a new design), and the turbojets the Comet was supplied with were much closer to modern engines than the 247's pistons anyway.
The monocoque aluminium shell and cantilevered (across the aisle!) wing of the 247 was its novelty, but I'm not sure cramped piston engined 10 seaters with 200mph maximum speed are really what people think of as "modern airliners"...
It takes a stretch to suggest that it was the plane described in the article rather than the Jet Age that marked the transition to what could be described as a "modern airliner".