WI the 737 was a jumbo?

In reading responses to my thread (plug:openedeyewink:), I came across a reference to a proposed twin L1011, called Bi-Star or Dash 600.

Googling turned up this:

tri_747.jpg

So, WI the 747 had been a trijet, or the 737 had been a jumbo? (One or the other is never designed or built.)

Does this butterfly the L1011 & DC-10? Or does it make them more successful? Does this mean the *73½7 (IDK what to call it:openedeyewink:) is the #1-selling jetliner in history? Or does being a jumbo hurt its sales?

Does a need for 3 engines, instead of four, mean all three have to be bigger & more powerful?

Does it get caught by regulators disapproving of fin-mounted engines?:openedeyewink:
 

SwampTiger

Banned
I am guessing you meant 727, not 737. Though not a fan of trijets, I will consider the issues. First, the 707-737 series used a six across seating with a 140 inch width. Jumbos are 80-100 inches wider, thus are much heavier. The P&W JT8D engines in the 727 ranged over time from 14,000 to 16,000 pounds thrust. The fuselage engines lost efficiency due to the S-duct. You will need bigger engines. The 727 fell behind other jets due to noise concerns, again the fuselage engine. By moving to a lesser offset in the S-duct, like Lockheed and McDonnell-Douglas, Boeing could have kept the 727 going. If Pratt&Whitney had used a similar fan design development from the JT3 to JT8 to create a more powerful JT4, you may see a more powerful medium bypass engine earlier in time for this aircraft. The JT9 appears later.

The problem with jumbos in the early to mid 60's is lack of demand and suitable airports. Demand grew during the 60's, which led to the jumbo's entering service in 1970. A short, stubby, widebody airliner may be possible for short field and regional routes in the time frame you are considering.
 
Tri-jets (Boeing 727 and British Trident) were popular during the 1960s and 1970s because Extended Twin-engined Operations (ETOPS) were limited to 60 minutes from any alternate airport. As engines became more reliable during the 1980s, ETOPS were expanded to allow Trans-Atlantic routes for twins.
They also needed a flight engineer to manage complex fuel and hydraulics systems. Some carried navigators on longer routes. As fuel systems were computerized, flight engineers disappearred from newer designs. Navigators were replaced by sophisticated avionics including GPS. Reducing flight crew to a pair of pilots vastly reduced labour costs for airlines.

Boeing’s 727 was noisy for two reasons: older low-bypass engines (JT8D) and high-lift devices. 727s were so loud they were banned from many airports.
Part of the solution was hush-kits that included diffusers to mix hot, fast exhaust air with cooler, slower ambient air. Reducing shearing between the two different air masses reduced noise.

The other problem was the 727’s impressive high-lit devices. It had the usual trailer edge flaps, but it’s clean wing leading edges permitted installation of Krueger flaps onboard and slats near the wing tips. The combination generated so much additional lift that medium-range 727s could still land on shorter runways at holiday destinations. The disadvantage was the that high-lift devices also generated massive amounts of drag. To counter all the extra drag - and high rates of descent - 727s needed to carry lots of power on final approach. This extra power generated extra noise which annoyed people living near airports. High-lift devices also created stability problems when extended the full 40 degrees. Stability problems led some airlines to restrict flap extension to 30 degrees. Raisbeck used this approach (please excuse the pun) to develop a hush-kit that started by limiting flap extension, which allowed lower power settings during final approach.
 
Yes.
Reducing the number of people engines does require bigger and more powerful engines. Currently the most powerful engines are the pair of General Electric 900 series turbofans installed on Boeing 777 airliners. GE 900 series engines sport 330 cm diameter fans that are the largest ever flown and they can generate up to 115,540 pounds of thrust making them the most powerful jet engines to date. They are also among the most fuel-efficient allowing Boeing 777 which can fly longer routes than 4-engined 747s. 777 can fly more than half way around the planet on internal fuel! Two engines are less expensive than four.

Ducting for the center engine could have been vastly straightened by slightly off-setting it to one side of th vertical fin. This move is would also vastly simplify the structure in the vertical fin. Eventually it would also simplify re-engineing as quieter and more fuel-efficient turbofans were perfected.

Boeing NG considered redesigning the 727 with turbofans but concluded that increasing the diameter of the center engine’s ducting would require (expensively) completely resist I think the vertical fin.
 
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SwampTiger

Banned
Yes, you need two much more powerful engines, or four engines to avoid the S-duct. The problem centers around the S-duct and the need for increased power with a heavier, draggier aircraft at takeoff and landing. So, either a fatter 707 or 737 with greater engine power. Plus hoping the engine reliability improves quickly. A commercial engine with 100,000 pounds thrust is unlikely in the 60's. 30-40,000 pound thrust engine arrived at the end of the decade.
 
I am guessing you meant 727, not 737.
Somehow, I can never keep them straight...:oops::oops:

OTOH, since I'm picturing wing-podded engines, with a DC-10 layout, maybe not... (Tho that's more, "WI Boeing built the DC-10?"...:openedeyewink:)
Though not a fan of trijets
Personally, I think a fin-mounted engine is stupid & dangerous.:eek: However, for the sake of discussion (& because a trijet *747 is cool;)).
The fuselage engines lost efficiency due to the S-duct. You will need bigger engines. ...If Pratt&Whitney had used a similar fan design development from the JT3 to JT8 to create a more powerful JT4, you may see a more powerful medium bypass engine earlier in time for this aircraft. The JT9 appears later.
That works for me. (I had an odd idea, which probably isn't practical: two fin engines, side-by-side.)
The problem with jumbos in the early to mid 60's is lack of demand and suitable airports. Demand grew during the 60's, which led to the jumbo's entering service in 1970. A short, stubby, widebody airliner may be possible for short field and regional routes in the time frame you are considering.
That works. I have a hunch this would appeal to high-traffic routes in Japan, perhaps PRC/ROC, perhaps Bosyorkington, & maybe London-Paris or something. Transcontinental or transatlantic probably still goes to "narrowbodies" for awhile yet.

OTOH, what happens if Boeing decides not to build the OTL 747, & instead converts the 727 (or 737) to a jumbo?

As for the S-duct, if this is a clean sheet of paper, that doesn't pertain, does it? So... (And DC-10, again.:openedeyewink:)
the diameter of the 777 engine is huge, you could put a 737 fuselage in side it.
:eek::eek::eek:
 
The 707 set the template for Boeing and since the DC-8 had the same layout perhaps Douglas (and even Convair). Both VC-10 and the Russians showed big tail mounted layout is still viable. The 727 was a compromise but in the end made for the most adaptable plane sold, only the 737 being as successfully general purpose, but in some alternate time I think the next generation from 707 would have been a wide-bodied three engine and the follow on to 727 a twin engine, either DC-9 like or like the 737, had they both not been so long serving and selling. If you butterfly 747 then Boeing should have built something like the L-1011/DC-10 as its long-range or higher capacity 707 replacement (we can number it 737 for fun-it has three engines!) Having Boeing falter or its competitors do better or the SST be taken more seriously sooner could stagnate big jets at the DC-10 scale and butterfly 747. So perhaps Boeing builds this TLs L-1011 (aesthetically an upsized 727) and Douglas the DC-10, dividing the market otherwise going to these and 747 with maybe a better showing from Europe for interest. That should bridge us to the ETOPS era and the coming of 757/767 and really 777.

I did this with my ATL, using the tail mounted engine layout as the preferred template from European builders, especially the British and Russians, who have more places in under improved areas, high or hot or dirty, while the USA goes more for underwing since I allow for a more improved domestic airport infrastructure. I have Germany doing more of both as it has a larger continental Europe and USA market and lesser "third world" export market. Here the wide-bodies failed to jump above the L-1011/DC-10 and bigger "narrow" bodies remain competitive with improved engines and modern cockpits since SSTs get build in albeit niche quantity but kill off bigger economy model flying until the big twin engine revolution!
 
The 707 set the template for Boeing and since the DC-8 had the same layout perhaps Douglas (and even Convair)....
That's all very interesting stuff, with interesting ramifications. It crosses my mind this might mean an earlier Airbus. It might also mean Lockheed in trouble sooner (without the income from sales of the L-1011, essentially shut out by the 400pd gorillas...)

At the same time, I wonder if Boeing could say to the engine makers, "Okay, we've got this thing on the drawing board, we need this much thrust & this much fuel economy, can you give us an engine that will make it work by the time we're ready to cut metal?" (Which might butterfly away the need for a triple...:oops: tho I have a hunch getting three v two will end up happening, the way the Derwents replaced the projected AJ.65s in the C.102. {Presuming Boeing doesn't say, "Hmm...what about 6 engines?":openedeyewink:})
 
My theory is that the next generation of aircraft get bigger but reduce engines as they in turn get more powerful thus the four engine 707 is replaced by a three engine aircraft with more seats or greater range, the 727 goes from three engines to two and opens the path towards ETOPS as it flies short over water routes, and ultimately just two engines in all models. I have pondered if a four engine long range aircraft is still built, akin to A340, but that seems a niche product in a market roughly shared by USA, UK and German manufacturers, not taking into account France, Russia or Japan. Basically I have a 707 then 727 then L-1011 and DC9 evolution before we get to the SST and 757/767 era.

For me I have Douglas and Lockheed rather dominant in the 1940/50s with DC-3/4/6 and Constellation with everyone else playing catch up, the British have as good a captive market in the Empire as the USA has a domestic one, Germany has Luft Hansa but needs exports to keep in the game so I have them building stuff aimed at the global market. I am tinkering with the Anglo-French alliance and maybe an American partner as Germany's consolidating industry gets a US partner. In my world it might be Douglas, Lockheed and Convair battling to survive as without WWII the B-29 and hence 377 are very much under butterfly wings thus putting into question who builds TLs 707 first.

I m curious how much the manufacturer and engine makers collaborated then, for me I have Jumo, BMW or Heinkel's in-house jet development so at least Germany might have combined engine and airframe makers?
 
I am guessing you meant 727, not 737. Though not a fan of trijets, I will consider the issues. First, the 707-737 series used a six across seating with a 140 inch width. Jumbos are 80-100 inches wider, thus are much heavier. The P&W JT8D engines in the 727 ranged over time from 14,000 to 16,000 pounds thrust. The fuselage engines lost efficiency due to the S-duct. You will need bigger engines. The 727 fell behind other jets due to noise concerns, again the fuselage engine. By moving to a lesser offset in the S-duct, like Lockheed and McDonnell-Douglas, Boeing could have kept the 727 going. If Pratt&Whitney had used a similar fan design development from the JT3 to JT8 to create a more powerful JT4, you may see a more powerful medium bypass engine earlier in time for this aircraft. The JT9 appears later.

The problem with jumbos in the early to mid 60's is lack of demand and suitable airports. Demand grew during the 60's, which led to the jumbo's entering service in 1970. A short, stubby, widebody airliner may be possible for short field and regional routes in the time frame you are considering.

Another problem with jumbos before the late 1960s is lack of a suitable powerplant producing sufficient thrust with an acceptable rate of fuel consumption. The JT9D wasn't first run until late 1966 and after that, had immense problems that weren't solved until 1969. If you look at jetliner development through the prism of powerplant development and availability, the 727-DC9-737-747 progression makes sense. The story of the 727 as a trijet has everything to do with overwater operations; in this pre-ETOPS era, two engines weren't enough for extended overwater operations. Eastern Air Lines, was one of the first two operators and they had routes overwater between the Northeast and Florida and in the Caribbean. The other carrier was United which had a need for high temperature/altitude capability for its Denver operation. That also required three engines. The early JT8D just didn't have the thrust to make hot and high work on two engines.
 
If we look at the JT8D, a development of a military engine, that went into the 737, early 737 and DC9, the logic of three engines and the evolution towards two can be seen. I am not versed enough to know if it is better to redesign the tail for two better higher bypass engines or clean sheet a twin engine. A rear mounted twin gives the stairs and those might remain a selling point in regional or lesser developed nations applications, unlike the 737 which is in my mind a true "air bus". For domestic USA and continental Europe the 737 looks "right" sized to be jack-of-all-trades, the path forged by the 727. I am not aware of the development costs on the engines but I imagine they are not insignificant, so having an engine funded by military needs and adapted and usable over more than one aircraft looks to be about ideal. Thus I tend to map out things around an engine that can be fit to the scale of the plane in two, three or four layout. Not real engineering but it seems to be realistic. Thus the first "jumbo" needs four of these size engines or in order to actually get bigger a yet more powerful engine, roughly double or more in power to go from 727 to 747 or DC-10. At the jumbo size the third engine is really a stop-gap awaiting the bigger engines and ETOPS but it makes sense as the 737 despite not fitting the numbering, 707 with 4 engines, 727 with 3, 737 with 2 (or 4), so 747 should have 3, odd numbers even engines, even numbers odd engines. Laughing out loud.
 

SwampTiger

Banned
Pratt & Whitney offered a low-bypass fan jet based on the J75 called JT4 to manufacturers in 1959. The J75 was 25-30% more powerful than the J57/JT3. No airline ordered the engine. The J57/JT3 grew from the JT3C to the JT3D as a low-bypass engine. With a more far-sighted aircraft manufacturer, you may have a partial solution to your power problem by 1962/3.
 
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