hitower3
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An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Wed Jan 09, 2019 1:01 pm

Dear fellow A-netters,

Today, I am following up to an earlier, similar post https://www.airliners.net/forum/viewtopic.php?f=5&t=1388811 where I compared the performance and economics of an A321-200LR to a Boeing B707-320B, which was found interesting by quite a few readers.
For this second round of comparison, I have again chosen a few aircraft that are very different at first sight, but that also show some striking similarities in capacity and range. This comparison is aimed at allowing us to draw conclusions about the progress made in aeronautics over the last 65 years. Or possibly reveal some lack of progress in terms of efficiency gains?

OK, let's dive into the data!

Aircraft: Douglas DC-7C / Convair CV-880 22M / Airbus A220-100
Length: 34.21m / 39.42m / 35.0m
Wingspan: 38.86m / 36.58m / 35.1m
Wing area:152.1m2 / 185.8m2 / 112.3m2
OEW: 33.0t / 42.7t / 35.2t
MTOW: 64.9t / 92.5t / 60.8t
Pax capacity (typical): 105 / 110 / 108

Cruise speed (econ): 353kn / 535kn / 447kn
Range: 4000nm / 3350nm / 2950nm
Fuel consumption: 1350kg/h / 5600kg/h / 1570kg/h
Specific fuel consumption (kg per pax per 100nm): 3.64 / 9.52 / 3.25

Flight crew: 3 / 3 / 2

Looking at the data above, I would point out the following observations:
  • The transition from the last generation of piston engines to the first generation of jets caused a huge jump in fuel consumption (factor 2.6)
  • The continuous improvement of jet engines, aerodynamics and materials resulted in a dramatic reduction (factor 2.9) in fuel consumption between 1959 and 2013.
  • This continuous improvement allows the A220-100 to undercut the specific fuel consumption of the DC-7C by 11% (only!) yet flying less than 100kn (27%) faster.
  • I would point out that the price to pay for the speed gain of jets versus pistons was enormous. Had piston engines benefited from a similar improvement than jet engines, this technology might still be interesting, e.g. for cargo applications.

I kindly invite you to share your own observations.

Best regards,
Hendric
 
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ClassicLover
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Wed Jan 09, 2019 1:55 pm

hitower3 wrote:
I would point out that the price to pay for the speed gain of jets versus pistons was enormous. Had piston engines benefited from a similar improvement than jet engines, this technology might still be interesting, e.g. for cargo applications.


One of the reasons everyone switched to jets was the reliability of the powerplant. Piston engines were notorious for requiring a lot of maintenance due to so many moving parts, and for breaking down frequently, requiring engine changes. Much of this intensive maintenance and associated cost was simply removed once jets came onto the scene. I read somewhere that Qantas ordered too many replacement engines for their Boeing 707s as they based the amount they'd need on their historical requirement with the Lockheed Constellations.

Therefore, a whole host of costs associated with the DC-7 are not being accounted for in the like for like comparison. Great to see how close they are though, as aircraft on their own. I really liked seeing that! However, the modern A220 will still win out based on many of the other costs being lower. Great post!
I do enjoy a spot of flying, especially when it's not in economy!
 
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lightsaber
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Wed Jan 09, 2019 2:14 pm

ClassicLover wrote:
hitower3 wrote:
I would point out that the price to pay for the speed gain of jets versus pistons was enormous. Had piston engines benefited from a similar improvement than jet engines, this technology might still be interesting, e.g. for cargo applications.


One of the reasons everyone switched to jets was the reliability of the powerplant. Piston engines were notorious for requiring a lot of maintenance due to so many moving parts, and for breaking down frequently, requiring engine changes. Much of this intensive maintenance and associated cost was simply removed once jets came onto the scene. I read somewhere that Qantas ordered too many replacement engines for their Boeing 707s as they based the amount they'd need on their historical requirement with the Lockheed Constellations.

Therefore, a whole host of costs associated with the DC-7 are not being accounted for in the like for like comparison. Great to see how close they are though, as aircraft on their own. I really liked seeing that! However, the modern A220 will still win out based on many of the other costs being lower. Great post!

The time needed for a piston engine's maintenance was amazing. One of my good friends, just a few years older than me, was trained on timing a multi-row radial engine. A half shift event that had to happen weekly (or more) per aircraft. Now piston engine's benefit from electronic controls (e.g., your car), so this is no longer an issue.

For piston engine's planes, ever 4 engines plane required one and a half spare engines. Ever seen photos of WW2 maintenance yards? You will see a squadron of 12 fighters had to keep eight to twelve spare engines on hand to keep flying! The higher number is later in the war as quantity trumped quality pretty much universally.

Maintenance really made a difference on the Airframe too. A piston Airframe was so shooken it needed to be adjusted far more than a jet. For example, the Ju-88 was considered amazing from a maintenance perspective as it could be flown 9 flights per day. No Hawaiian 17 during peak season with a propeller.

Also, when a propeller was nicked, everyone felt it. The vibration and noise were bad. You also smelled the engine lubricants all flight. Some people had digestive issues due to the laxative effect.

That brings up utilization and crew costs. If the flight takes longer, you pay the crew more for the flight. When fuel became pricey, the time savings stopped paying off except for those who can afford a business jet anyway.

Lightsaber

PS, where did the 1570 kg/hr for the A220 come from. That is better than the numbers I have. I think all three planes have their fuel burn underestimated for a mission by a significant amount.
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TurboJet707
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Wed Jan 09, 2019 2:22 pm

Thanks, that's a very interesting exercise. Some people may question the use of it, but I think it's a good and funny way to put things into perspective.

That CV880 fuel burn is really frightening :shock: I wonder how this would compare in absolute terms with a modern large widebody like, let's say, a B777-300ER.
And would have thought that the difference in specific fuel consumption between the early 1950's DC7C and the super-modern A220 would be so small...

The difference in wing area is also quite interesting. The CV880 did have a huge wing for such a relatively small jetliner. I once read that the CV880 was given a large wing area to enable it to land at and take off from smaller airports (Convair saw a niche for a very fast medium-haul aircraft), but Convair realised that this large wing could hold so much fuel that might as well make the plane a long-haul aircraft... After all, the perceived niche wasn't there and the CV880 went on to become a commercial failure with just 65 built. Still, a fascinating beast... :airplane:
Last edited by TurboJet707 on Wed Jan 09, 2019 2:27 pm, edited 2 times in total.
 
Tan Flyr
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Wed Jan 09, 2019 2:25 pm

one of the other things about fuel is the cost difference, even in the late 50's , between Av-Gas and Jet-A. I recall in two different airline biographies notes about that transition. In one on Delta someone from accounting was on board a DC-8 demo flight and nearly fainted when he saw the fuel consumption rates in the cockpit, until it was expalined to him it was Kerosene not Av-Gas.
and in American's (by Serling?) , as AA prepared for the 707's they signed a deal with Texaco for a million gallons of Jet-A for a dime or such per gallon.

I'm going to guess that in the late 50's if even premium auto gas was 30-35 cents a gallon, Aviation Hi Octane was probably 50 cents? My point being, the relative cost of fuel per seat mile.

While the CV-880 ( the best comparison? maybe a B-720?) gobbled kerosene, it was darn cheap . Maybe someone has the average cost of Av-gas back then, but I'm betting that with current (historic last 3 year averages) the cost comparisons on fuel will be quite interesting.
 
GalaxyFlyer
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Wed Jan 09, 2019 2:38 pm

100/130 was $0.52 a gallon in 1972, when auto fuel was probably half that.

GF
 
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Wed Jan 09, 2019 2:50 pm

TurboJet707 wrote:
Thanks, that's a very interesting exercise. Some people may question the use of it, but I think it's a good and funny way to put things into perspective.

That CV880 fuel burn is really frightening :shock: I wonder how this would compare in absolute terms with a modern large widebody like, let's say, a B777-300ER.
And would have thought that the difference in specific fuel consumption between the early 1950's DC7C and the super-modern A220 would be so small...

The difference in wing area is also quite interesting. The CV880 did have a huge wing for such a relatively small jetliner. I once read that the CV880 was given a large wing area to enable it to land at and take off from smaller airports (Convair saw a niche for a very fast medium-haul aircraft), but Convair realised that this large wing could hold so much fuel that might as well make the plane a long-haul aircraft... After all, the perceived niche wasn't there and the CV880 went on to become a commercial failure with just 65 built. Still, a fascinating beast... :airplane:


Some thoughts:

I too am shocked by the relative fuel efficiency of a DC-7C.

The CV880 had poor fuel economy by 1950s standards, which is saying something.

I'd be curious about how something like a Q400 would stack up. It (sort of) bridges the gap technologically between the DC-7C and the A220. It uses a turbine engine for reliability, but uses a propeller and travels more slowly than an A220, like the DC-7C. It would be hard to do an apples-to-apples comparison due to its short range and fewer passengers though.

I'm curious what the optimal speed for maximum fuel efficiency is in flight. There was a time when increased speed ruled the roost of design, but efficiency now leads the day.
 
hitower3
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Wed Jan 09, 2019 3:06 pm

lightsaber wrote:
PS, where did the 1570 kg/hr for the A220 come from. That is better than the numbers I have. I think all three planes have their fuel burn underestimated for a mission by a significant amount.


Dear lightsaber,

Thank you very much for your answer.
I have taken the fuel burn figures (all 3 of them) from numbers published in the thread where a list of hourly burn was published for a lot of airplane types.
https://www.airliners.net/forum/viewtopic.php?t=1355819

Also, I reckon that 1950s piston airplanes required a LOT more maintenance than 1960's jets. I have the impression though, that this fragility of the DC7 and Super Connies arose from the fact that their engines were pushing the limits of what was technically feasible with piston engines. Weren't the DC3 much easier to maintain than the later hot rods?
I tend to see the DC7 / Super Connie among the piston aircraft like the Concorde among the jets: technology pushed to (or beyond) the limits results in a hangar queen...
 
hitower3
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Wed Jan 09, 2019 3:15 pm

Tan Flyr wrote:
I'm going to guess that in the late 50's if even premium auto gas was 30-35 cents a gallon, Aviation Hi Octane was probably 50 cents? My point being, the relative cost of fuel per seat mile.

While the CV-880 ( the best comparison? maybe a B-720?) gobbled kerosene, it was darn cheap . Maybe someone has the average cost of Av-gas back then, but I'm betting that with current (historic last 3 year averages) the cost comparisons on fuel will be quite interesting.


Dear Tan Flyr,

Thank you for your input. I have indeed not considered the apparently significant cost delta between Jet A-1 and AvGas.
I agree that the CV-880 was a fuel guzzler even back then, but it still fits better in my comparison in terms of capacity and range, compared to a B720 which could carry some 150 pax...

Best regards!
Hendric
 
smartplane
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Wed Jan 09, 2019 5:38 pm

Thought provoking and interesting comparisons.

Suspect the fuel burn rates for the first two are at optimum altitude, so no allowance for take off.

A DC7C could travel 4,000nm at max payload with 105 passengers! With max fuel and a few passengers maybe.
 
timz
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Wed Jan 09, 2019 6:34 pm

DC-7C economical cruise would be more like 260-270 knots. Typical seat count ... maybe 70-75 on international flights.

Econ cruise for a CV880 is less than 500 knots, of course, and don't plan to fly 3300 nm with it.
 
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Thu Jan 10, 2019 4:17 am

hitower3 wrote:
Aircraft: Douglas DC-7C / Convair CV-880 22M / Airbus A220-100
OEW: 33.0t / 42.7t / 35.2t
MTOW: 64.9t / 92.5t / 60.8t


It's strange to me that the structural efficiency (OEW/MTOW) is so much worse for the A220 than the others.
DC-7: 51%
CV-880: 46%
A220: 58%.

Carbon fibre is weaker than 1950's aluminum? Design tools were better in 1950??
 
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Thu Jan 10, 2019 4:06 pm

lightsaber wrote:
ClassicLover wrote:
hitower3 wrote:
I would point out that the price to pay for the speed gain of jets versus pistons was enormous. Had piston engines benefited from a similar improvement than jet engines, this technology might still be interesting, e.g. for cargo applications.


One of the reasons everyone switched to jets was the reliability of the powerplant. Piston engines were notorious for requiring a lot of maintenance due to so many moving parts, and for breaking down frequently, requiring engine changes. Much of this intensive maintenance and associated cost was simply removed once jets came onto the scene. I read somewhere that Qantas ordered too many replacement engines for their Boeing 707s as they based the amount they'd need on their historical requirement with the Lockheed Constellations.


Therefore, a whole host of costs associated with the DC-7 are not being accounted for in the like for like comparison. Great to see how close they are though, as aircraft on their own. I really liked seeing that! However, the modern A220 will still win out based on many of the other costs being lower. Great post!

The time needed for a piston engine's maintenance was amazing. One of my good friends, just a few years older than me, was trained on timing a multi-row radial engine. A half shift event that had to happen weekly (or more) per aircraft. Now piston engine's benefit from electronic controls (e.g., your car), so this is no longer an issue.

For piston engine's planes, ever 4 engines plane required one and a half spare engines. Ever seen photos of WW2 maintenance yards? You will see a squadron of 12 fighters had to keep eight to twelve spare engines on hand to keep flying! The higher number is later in the war as quantity trumped quality pretty much universally.

Maintenance really made a difference on the Airframe too. A piston Airframe was so shooken it needed to be adjusted far more than a jet. For example, the Ju-88 was considered amazing from a maintenance perspective as it could be flown 9 flights per day. No Hawaiian 17 during peak season with a propeller.

Also, when a propeller was nicked, everyone felt it. The vibration and noise were bad. You also smelled the engine lubricants all flight. Some people had digestive issues due to the laxative effect.

That brings up utilization and crew costs. If the flight takes longer, you pay the crew more for the flight. When fuel became pricey, the time savings stopped paying off except for those who can afford a business jet anyway.

Lightsaber



Didn't the Boeing 377 Stratocruiser suffer from the same vibration issues? I know Pan Am lost as least one due to engine failure (and possibly more), and the Electra gave us the term "whirlmode", but the too-many-moving-parts piston engine wasn't ever really suited to any airplane.

I remember flying in a Convair CV-440 in 1974 that nearly shook my teeth out of my head. The one hour flight from the brand-new DFW to Fort Smith, Arkansas, for this eight-year-old boy was a blast, but I think I vibrated until I fell asleep that night.

Ironic that I now live about five miles as the crow flies from San Diego International Airport and the former Convair plant that built all of the company's passenger airplanes. I don't get on the stretch of Interstate 5 that passes by the airport, but when I do, I always picture a Convair 880 or 990 in TWA colors getting ready for a test flight.

Were the 880 and 990 the most fuel-hungry airplanes ever per unit cost?
 
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Thu Jan 10, 2019 6:11 pm

The choice of the DC-7C here is interesting as it was essentially the tail end of the development of piston engined long haulers. It employed the Wright R-3350-988TC18EA1-2 engines, which were the absolute bleeding edge for power and fuel economy for piston aviation engines. The TC stood for Turbo-Compound, which had power recovery turbines plumbed into the exhaust stacks to directly recover energy lost from pumping the exhaust gases out of the engine back to the crank shaft. This introduced a great deal of both mechanical and thermal stress to the system which caused a substantial hit to the reliability of the engines themselves that took years and years to straighten out. My father was a mechanic for a major during the era and used to lament at the extreme amounts of maintenance that those engines used to require.
 
incitatus
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Thu Jan 10, 2019 7:26 pm

A very interesting comparison. In spite of the longer range, I think the A220 is smack in the middle of the route profile of the 727-100 in the 1960s. That would be a fair comparison.
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kaitak
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Thu Jan 10, 2019 8:19 pm

I remember talking to an EI pilot many years ago; he started his career on 720s (115 seats) and retired as an A330 captain (320 seats); the fuel burn on both was pretty similar - about 5t an hour. That's a pretty impressive improvement over the years. I'd love to find out how the current crop of widebodies - A350/787 - compare to earlier aircraft of similar capacity - DC10/L1011/A300/747SP.
 
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Thu Jan 10, 2019 9:18 pm

kaitak wrote:
I'd love to find out how the current crop of widebodies - A350/787 - compare to earlier aircraft of similar capacity - DC10/L1011/A300/747SP.


The following comparison is indeed very interesting: DC-10-30 / A340-300E / A359 since they are close in terms of MTOW and fuel capacity:
MTOW (t): 251.7 / 275 / 280
fuel (l): 137500 / 140600 / 140800
std seating: 270 / 295 / 325 (not sure if this reflects similar densities)
range (nm): 5200 / 7150 / 8100

Assuming 6% fuel reserve, the pax.nm/l ratio comes in respectively at: 10.9 / 16 / 19.9.
 
SFOThinker
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Thu Jan 10, 2019 9:21 pm

I was lucky as a teen to fly on a DC-7 (UA) and DC-6Bs (Western, Delta, UA). I was shocked to watch the 7s retired much quicker. But I think I recall being surprised that the 7 was noisier. However, noise on prop airliners depended a lot on where you sat, so my comparison may be meaningless.
Does anyone know if the DC-7 was noisier?
 
IADCA
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Thu Jan 10, 2019 9:42 pm

kitplane01 wrote:
hitower3 wrote:
Aircraft: Douglas DC-7C / Convair CV-880 22M / Airbus A220-100
OEW: 33.0t / 42.7t / 35.2t
MTOW: 64.9t / 92.5t / 60.8t


It's strange to me that the structural efficiency (OEW/MTOW) is so much worse for the A220 than the others.
DC-7: 51%
CV-880: 46%
A220: 58%.

Carbon fibre is weaker than 1950's aluminum? Design tools were better in 1950??


I wonder how much of that is a function of structural MTOW versus "paper" MTOW. I suspect the changing certification requirements since the 880 was certified may functionally require a larger buffer between a structure's true failure rate versus operational MTOW.
 
ultrapig
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Thu Jan 10, 2019 10:10 pm

Thanks very much-Maybe you can point me to a thread or answer this question. I see that United is going to use the 787-10 to fly from the east to west coast. Comfort aside, what is the cost per seat mile on such a trip for the 787-10 versus a 737-900er?
 
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kitplane01
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Fri Jan 11, 2019 7:26 am

IADCA wrote:
kitplane01 wrote:
hitower3 wrote:
Aircraft: Douglas DC-7C / Convair CV-880 22M / Airbus A220-100
OEW: 33.0t / 42.7t / 35.2t
MTOW: 64.9t / 92.5t / 60.8t


It's strange to me that the structural efficiency (OEW/MTOW) is so much worse for the A220 than the others.
DC-7: 51%
CV-880: 46%
A220: 58%.

Carbon fibre is weaker than 1950's aluminum? Design tools were better in 1950??


I wonder how much of that is a function of structural MTOW versus "paper" MTOW. I suspect the changing certification requirements since the 880 was certified may functionally require a larger buffer between a structure's true failure rate versus operational MTOW.


I don't know what "paper mtow" is.

Of course certification has changed in many many ways. But the positive limit maneuvering load factor is 2.5 now. Has it always been 2.5???
 
hitower3
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Fri Jan 11, 2019 9:26 am

kitplane01 wrote:

It's strange to me that the structural efficiency (OEW/MTOW) is so much worse for the A220 than the others.
DC-7: 51%
CV-880: 46%
A220: 58%.

Carbon fibre is weaker than 1950's aluminum? Design tools were better in 1950??


Hello kitplane,

I am very confident that both materials and construction tools are better now than they were in the 1950s.
The reason why the A220 seems to fall "behind" its older siblings is probably a design decision - there is simply no need to increase MTOW further, as the aircraft can fulfill its mission profile (payload and range) with these given weights. Let's compare the OEW/MTOW ratio of the A220 with other aircraft in the same market segment:
A220-100: 58%
A220-300: 54.9%
A319-100: 54%
A320-200: 54.6%
B737-600: 55.9%
B737-700: 53.7%
E190-E2: 58.5%

Now let's take some modern (ultra) long range models:
A350-900: 50%
A350-1000: 50.2%
B787-9: 50.7%

Looking at the data provided, we can conclude that regional airliners typically achieve a OEW/MTOW ratio of 55%, while long range airliners are around 50%. The 46% figure is an outlier, maybe the data is wrong, e.g. the OEW is actually a MEW?
 
IADCA
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Fri Jan 11, 2019 4:10 pm

kitplane01 wrote:
IADCA wrote:
kitplane01 wrote:

It's strange to me that the structural efficiency (OEW/MTOW) is so much worse for the A220 than the others.
DC-7: 51%
CV-880: 46%
A220: 58%.

Carbon fibre is weaker than 1950's aluminum? Design tools were better in 1950??


I wonder how much of that is a function of structural MTOW versus "paper" MTOW. I suspect the changing certification requirements since the 880 was certified may functionally require a larger buffer between a structure's true failure rate versus operational MTOW.


I don't know what "paper mtow" is.

Of course certification has changed in many many ways. But the positive limit maneuvering load factor is 2.5 now. Has it always been 2.5???


Yes, the hard limit has always been 2.5, but the calculation changed in 1974: https://www.govinfo.gov/content/pkg/FR- ... pdf#page=1 (versus https://www.govinfo.gov/content/pkg/FR- ... pdf#page=1) to provide the full text as is current, which is at: https://www.law.cornell.edu/cfr/text/14/25.337.

What I mean by a "paper" MTOW is certifying an airframe or a version thereof as having a lower MTOW than the structure would actually support to save on landing fees or otherwise manipulate to fit within other regulatory or contractual provisions. If operators need a higher-MTOW version for some reason, it can often be done with minimal effort. It seems like there's a decent chance of this with the A220, which seems to not be getting used at the upper end of its range envelope and therefore not actually needing to push the takeoff weight all the way up.
 
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kitplane01
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Sat Jan 12, 2019 3:02 am

hitower3 wrote:
kitplane01 wrote:

It's strange to me that the structural efficiency (OEW/MTOW) is so much worse for the A220 than the others.
DC-7: 51%
CV-880: 46%
A220: 58%.

Carbon fibre is weaker than 1950's aluminum? Design tools were better in 1950??


Hello kitplane,

I am very confident that both materials and construction tools are better now than they were in the 1950s.
The reason why the A220 seems to fall "behind" its older siblings is probably a design decision - there is simply no need to increase MTOW further, as the aircraft can fulfill its mission profile (payload and range) with these given weights. Let's compare the OEW/MTOW ratio of the A220 with other aircraft in the same market segment:
A220-100: 58%
A220-300: 54.9%
A319-100: 54%
A320-200: 54.6%
B737-600: 55.9%
B737-700: 53.7%
E190-E2: 58.5%

Now let's take some modern (ultra) long range models:
A350-900: 50%
A350-1000: 50.2%
B787-9: 50.7%

Looking at the data provided, we can conclude that regional airliners typically achieve a OEW/MTOW ratio of 55%, while long range airliners are around 50%. The 46% figure is an outlier, maybe the data is wrong, e.g. the OEW is actually a MEW?


I don't think that makes sense. You wrote "The reason why the A220 seems to fall "behind" its older siblings is probably a design decision - there is simply no need to increase MTOW further". Sure. But given some mission, they would surely want to minimize structural weight for fuel savings. The structure_weight / payload for the A220 is worse than the DC-7 or the CV880. In fact, the structure / payload of the DC-7 and the CV-880 is better than the A320 and the 737. Weird.
 
ImperialEagle
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Re: An unfair comparison II - DC-7 vs. CV-880 vs. A220-100

Sat Jan 12, 2019 3:42 am

[quote="SFOThinker"]I was lucky as a teen to fly on a DC-7 (UA) and DC-6Bs (Western, Delta, UA). I was shocked to watch the 7s retired much quicker. But I think I recall being surprised that the 7 was noisier. However, noise on prop airliners depended a lot on where you sat, so my comparison may be meaningless.
Does anyone know if the DC-7 was noisier?[/quote

The PW 2800's and the Wright 3350's had very distinctive sounds. However, the propeller could make a big difference.
The C-46, Convair 240/340/440's, Martin 202/404's, and the DC-6's all had PW 2800's and had very different sounds to them. Especially a C-46 equipped with a 3-blade HS propeller! The -6's had a cross over exhaust so the stacks were on the side away from the fuselage. All of these had pretty loud propeller "beat" against the fuselage, but, the C-46 was downright deafening and painful at high power. You learned to stuff ear plugs in to endure the take-off. The cockpit was the worst!

The TC 3350's had a much deeper tone to them especially at take off power settings. If passing overhead on landing you could really hear those turbines.
If sitting in 4A and especially 4D you were in for a pretty loud take off on a -7 or -7B. The engines on a -7C were about five feet further out on the wing so that helped, especially with the propeller "beat" against the fuselage.

The detonation systems were very complicated, and oil consumption could be more critical than fuel load sometimes. Heat was also a big issue. The TC 3350's were sensitive to the shift between low-blower and high-blower. If the weather was cooperating, it was best to stay at lower altitudes in low-blower.
"If everything seems under control, you're just not going fast enough!"

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