de Havilland Comet would not have been successful anyway?

[SactoMan101]

Let's say the de Havilland Comet I managed to avoid the structural fatigue issues that grounded the plane by 1954.

It is of my personal opinion that the Comet would only have been a fleeting success--its very design limited the potential for design improvements, especially since the jet engines buried in the wings limited the potential for more powerful and better engines. The Boeing 707 and Douglas DC-8 would still have enjoyed a lot more success by 1960, since with podded engine mounts, Boeing and Douglas could easily incorporate replacements for the original engines with much more powerful engines in the longer term, which would allow higher mean takeoff weight (MTOW) versions with more fuel capacity for much longer range.

Comments?

 

[e of pi]

It is of my personal opinion that the Comet would only have been a fleeting success--its very design limited the potential for design improvements, especially since the jet engines buried in the wings limited the potential for more powerful and better engines. The Boeing 707 and Douglas DC-8 would still have enjoyed a lot more success by 1960, since with podded engine mounts, Boeing and Douglas could easily incorporate replacements for the original engines with much more powerful engines in the longer term, which would allow higher mean takeoff weight (MTOW) versions with more fuel capacity for much longer range.

I think I'd agree. In addition to being a bit easier to re-engine, the 707 and DC-8 were also larger (about triple the size), faster (by almost 100 mph!) and longer ranged (again, by almost a factor of two). More than the ability to more easily maintain the engines, this was going to have critical implications for operational utility and cost effectiveness of the Comet vs. the DC-8/707.

 

[Riain]

I wouldn't think the Comet was a competitor with the 707, the Comet was a first generation airliner and entered service 5 years earlier, If you're looking for a 707 competitor the VC7/V1000 is a better bet. In addition the in-wing engine design isn't a major problem because high bypass engines in the 20,000lb thrust class didn't run until 1974, no high bypass 707 was sold. What's more the 727 had a similarly restricted design with the tail engine but I doubt people would consider that a failure.

 

[hugh lupus]

I've worked on Comets and built and maintained Nimrods and much as it pains me to say.... I think that though a beautiful aircraft ultimatly they would have been surpassed.
Even the later models were just a collection of adaptions and modifications.
The engines despite being buried in the wings were suprisingly easy to remove and refit; the times comparing favourably with podded engines of the period.
The rest of the aircraft in so far as its structure went was a pig to inspect and repair though.
What the Comet should have been IMO was the lead aircraft for a whole new family
Sadly though this never happened .
After the disaters the British aircraft industry and government lost its nerve.
Now a time line where that never happened would be interesting

 

[MattII]

Comets were a dead-end of themselves, but without the second accident (ie, they manage to find the fault before flights are resumed), I think it definitely could have gone a lot further.

 

[Delta Force]

The Comet still had significant growth potential. The Rolls-Royce RB.106 was a drop-in replacement for the Avon. In addition to allowing the de Havilland Comet to have increased performance, the English Electric Lightning, Hawker Hunter, Saab 35, and other aircraft would have benefited from it.

Going forward, the fuselage section could have been reused on a twin engine design, saving maintenance and development costs. The derivative could have served with British European Airways.

 

[pdf27]

Going forward, the fuselage section could have been reused on a twin engine design, saving maintenance and development costs. The derivative could have served with British European Airways.

It was - the Sud Aviation Caravelle did exactly that.

 

[Delta Force]

It was - the Sud Aviation Caravelle did exactly that.

I thought it only used the cockpit and engines?

 

[SactoMan101]

I thought it only used the cockpit and engines?

I believe much of the basic fuselage cross-section design, though of course the passenger windows had a much more rounded shape to help avoid the structural fatigue issues that doomed the original Comet I.

Indeed, it would have been interesting to see that instead of British European Airways driving the British aircraft industry crazy during the design of what became the Trident, they worked with the French aerospace industry to build the shorter-range Caravelle based on many Comet components--it would have been like the Concorde but eight years earlier.

 

[yulzari]

Of course the Comet would have been overtaken by the 707 in time. What it could have held onto in the market was to slip under the 707 which was optimised for the transatlantic routes.This is exactly where it spent the 1970s. The VC7/V1000 would have been the 707 direct competitor.

There was also a market for the Britannia looking back (and if they had got the thing into service as scheduled) which was totally unrecognised at the time. Cheap mass long distance cattle class. For some time the Icelandic Loftleiðir held the passenger capacity record with their Canadair CL 44J by packing the 186 peasants into as little space as possible. To quote from the late lamented Freddy Laker (re Concorde) 'it is better to take people across the Atlantic at half the price than half the time'. The Bristol Britannia became the Candair CL 44 whuch was marketed as the Rolls-Royce 400 PropJet by Loftleiðir with the slogan "We are the slowest but the lowest."http://en.wikipedia.org/wiki/Icelandic_Airlines#cite_note-22

 

[Devvy]

I'm an utter novice at aero engineering and dynamics here etc, but why are in-wing integrated engines so much worse then podded engines?

Do engines really get swapped around that much - as an ignorant passenger, I assumed that the engines get worked on as part of the plane rather then detaching them?

And I'd of thought that integrated engines would be much more aerodynamic, therefore saving fuel?

 

[pdf27]

I'm an utter novice at aero engineering and dynamics here etc, but why are in-wing integrated engines so much worse then podded engines?

Do engines really get swapped around that much - as an ignorant passenger, I assumed that the engines get worked on as part of the plane rather then detaching them?

And I'd of thought that integrated engines would be much more aerodynamic, therefore saving fuel?

Essentially they force you to have a thicker wing. At high speeds (forced on you because you want to cruise at high altitude for long range, so to keep the wing from being stupidly large you need to go fast to get enough lift from the thin air), relatively thick wings are inefficient.

Now it isn't all that simple - what counts is the ratio of thickness to chord length (the distance over the wing the air flows). Hence, if you've got a long chord you can have a thick wing just fine - and that also helps you make it lighter.

With turbojets or low-bypass turbofans it pretty much comes out in the wash - the difference in performance is pretty minimal. It's when you get to high-bypass jets in the 1970s onwards that the differences are very clear-cut in favour of podded engines - prior to that it's as much a matter of national style as anything else, and part of that IMHO is a hang-over from the dominant piston-engine styles. The British used inline engines which have a relatively small frontal area and can be installed buried into a wing without too much drama, while the US used radial engines which are much larger and so just that little bit too big to be efficiently buried. The first-generation jets followed this precedent, as much through industrial inertia as anything else IMHO.

 

[riggerrob]

deHavilland buried its Ghost engines in the wing roots in an attempt to hide their huge diameter. This minimized drag the same way as hiding engines in the fuselages of early jet fighters.
Ghosts had huge e
Diameter engine casings because of their centrifugal compressors, but they still had normal-sized exhausts.
Comet's configuration worked best with first and second generation jet engines. It was the first jet airliner built in Britain. In comparison the Avro Canada Jetliner and several early American jet bombers just bolted engines to the underside of the wing ala Messerschmitt 262.
While I agree with the original poster, I believe that is overly-critical. Comet was the best jet airliner the Brits could design during the 1940s. Under-slung engine pods were not seriously considered until the 1950s. Under-slung engine pods did not have a significant advantage until turbo-fans were introduced during the 1960s. By then the Comet's wing made it impossible to retrofit large diameter turbo-fans. The inlet holes through the wing spars were too small.
Try to think of the Comet as an important generation/stepping-stone in the development of jet airliners.

 

[e of pi]

I'm an utter novice at aero engineering and dynamics here etc, but why are in-wing integrated engines so much worse then podded engines?

Do engines really get swapped around that much - as an ignorant passenger, I assumed that the engines get worked on as part of the plane rather then detaching them?

From what I know, modern jet engines are up for serious servicing about twice a year, with more minor inspection and service in between. With a podded engine, you simply open the cowling doors and you can do a lot of basic work right on-wing. With a buried engine, you have much less access (after all, the wing's in the way of half the engine's components) and are more likely to have to go through the rigmarole of removing the engine from the plane entirely--which is, in turn, a much more complex process than with a podded engine. These are for modern engines--early jets had shorter times between overhauls, and thus experienced the difference more often.

 

[Devvy]

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Cheers for the explanations - interesting reading!

 

[pdf27]

...more likely to have to go through the rigmarole of removing the engine from the plane entirely--which is, in turn, a much more complex process than with a podded engine. These are for modern engines--early jets had shorter times between overhauls, and thus experienced the difference more often.

Actually, I'm not sure that's true. With in-wing engines you can make it easy to drop them straight out, at which point they're easier to work on than podded engines. Because podded engines are suspended from one point, and are out in the airflow, they need a much stiffer mounting while at the same time it's a single point so is harder to make stiff. That will make the mount heavy and intrusive compared to an in-wing mount.

Come to think of it, there's no reason you can't ensure that all the bits you need to service are on the underside of the engine and so easy to access just by opening the doors. Most of it is pumps, lubrication points and the like so will naturally be on the underside anyway - anything major to do with the rotating assembly would require removal anyway whether it was a podded or buried engine.

 

[PMN1]

The Comet still had significant growth potential. The Rolls-Royce RB.106 was a drop-in replacement for the Avon. In addition to allowing the de Havilland Comet to have increased performance, the English Electric Lightning, Hawker Hunter, Saab 35, and other aircraft would have benefited from it.

Going forward, the fuselage section could have been reused on a twin engine design, saving maintenance and development costs. The derivative could have served with British European Airways.

I've read the luggage handling was a bit of a mess, though how it was botched i've not read.

 

[Simon]

As other have said as an early mover even with later variants like the extended de Havilland Comet 2 and Comet 3/4 they're going to be overtaken by larger rivals like Boeing's 707. The three major benefits I can see of the Comet succeeding are continued confidence within the British aviation industry, since their competitors are likely to suffer the same aircraft failures as them de Havilland, and to a lesser extent British aviation, doesn't develop such a damaged reputation, and with no massive overreaction on safety issues the Bristol Britannia is able to enter service a number of years earlier allowing to sell a decent number before jets totally take over the market. If things look to be doing somewhat better then there's an outside chance that funding for Vickers' VC-1000/VC-7 could be continued which gives the industry a fighting chance, although they'd still probably bugger it all up with the de Havilland DH.121 later on.

 

[Mumbles]

Let's say the de Havilland Comet I managed to avoid the structural fatigue issues that grounded the plane by 1954.

It is of my personal opinion that the Comet would only have been a fleeting success--its very design limited the potential for design improvements, especially since the jet engines buried in the wings limited the potential for more powerful and better engines. The Boeing 707 and Douglas DC-8 would still have enjoyed a lot more success by 1960, since with podded engine mounts, Boeing and Douglas could easily incorporate replacements for the original engines with much more powerful engines in the longer term, which would allow higher mean takeoff weight (MTOW) versions with more fuel capacity for much longer range.

Comments?

I don't recall where I read it (in one of a couple of books I'll try and reference later), but there is a story about Boeing execs visiting the De Havilland factory in the late 40's or 50's and realising that for a number of reasons, scaling up Comet production to the point where it could compete on a sheer numbers basis with what Boeing could produce meant that the Comet was going to struggle to be a true threat to US producers anyway.

 

[fscott]

I'm an utter novice at aero engineering and dynamics here etc, but why are in-wing integrated engines so much worse then podded engines?

Do engines really get swapped around that much - as an ignorant passenger, I assumed that the engines get worked on as part of the plane rather then detaching them?

And I'd of thought that integrated engines would be much more aerodynamic, therefore saving fuel?

Like you I am not an expert but one advantage to podded engines is if the engine malfunctions the parts are contained, in theory, in the POD. If the engine is in the wing you have a much greater chance of loosing the wing.