Merry Christmas 2024

[facthunter]

Oh I wish. The front part of the COMET  frame/ skin . was astoundingly WEAK. De Havs have made a lot of blues over time.  Douglas built great airframes up to the DC7. In my view the DC-3 Rates as the worlds top Aeroplane for it's time.   Nev

[Grumpy Old Nasho]

13 minutes ago, facthunter said:

In my view the DC-3 Rates as the worlds top Aeroplane for it's time

I believe the DC-3 was intentionally over engineered, for what reason/s I'm not sure, but probably because it was initially designed for passenger carrying and needed to be safe and reliable.

[onetrack]

The simple fact remains, that the engineers who designed the Comet fuselage had no knowledge or experience of the stresses produced on the hull by pressurising an aircraft. Fracture mechanics were a field yet to be developed in the early 1950's.

 

It was the constant flexing from pressurisation and de-pressurisation that fractured the Comet fuselage - and it took 1,825 cycles of pressurisation and de-pressurisation in the water-filled pressure test tank, using G-ALYU, before the hull fractured, and gave the testers the clues.

The knowledge gained in the pressure test tank was reinforced, when the British Navy recovered the fuselage of G-ALYP from the Mediterranean Sea, and the fuselage fractures of G-ALYP were examined.

 

It was determined that the hull fractures around the windows propagated from tiny cracks in manufactured components used around the windows - less than 100 microns in size. The cracks all propagated from bolt and rivet holes, and the tiny cracks around the holes were there when the Comet was manufactured. In previously-manufactured aircraft, the tiny cracks were of no concern - but in the pressurised Comet, they were deadly.

As Nev says, the frame of the Comet was of inadequate strength - but the design strength would've been quite adequate for an unpressurised aircraft. De Havilland did do a lot of testing on the Comet, but the testing was disorganised, as regards the order of the testing.

 

The sad part is the Comet could've been a winner for Britain once the problems were sorted - but the Americans at Boeing were studying the Comet problem closely, and made sure the Boeing 707 didn't suffer from the same problem - thus ensuring the Boeing 707 dominated the start of the passenger jet aircraft age.

 

https://www.sciencedirect.com/topics/engineering/de-havilland-comets

[facthunter]

DeHavilland made known all of the results of it's tank testing regarding the Comet. Pressure cycles are a limiting factor on many Aircraft, if not all.. Nasho the Load factors don't vary for Pax and  manual loaded cargo.. The test is Empty Wt to max weight . That is, does it have a useful payload and range? Nev

[Grumpy Old Nasho]

40 minutes ago, facthunter said:

Nasho the Load factors don't vary for Pax and  manual loaded cargo.. The test is Empty Wt to max weight . That is, does it have a useful payload and range?

I'm sorry, I don't fully understand what you're getting at here.

[facthunter]

IF the Plane is built too strong it will be too heavy  and all these categories of planes are built to about the same "G" load factors. Ie NOT enough for my liking..   Nev

[Grumpy Old Nasho]

Well there's design quality also, that can keep the weight down. I suspect the Americans were more thorough with their R&D than the Poms.

The DC3 was perhaps a perfectly designed craft, in all aspects of it's design, and therefore excessive weight was possibly eliminated in the overall structure by reducing stress through correct design. Not like that silly long counter weight for the tail plane in the Hawker Typhoon, did you read about that? The counter weight was susceptible to harmonic vibration and eventually broke the plane in half, killing unsuspecting pilots.

 

Some times the Poms got things right, but other times got things horribly wrong.

[facthunter]

They did OK for a small Country. Bit slow to get away from Multi engined wooden Biplanes. Schneider Trophy experience set them up for Spitfire Production, Sea Fury was a good performer . Hurricanes did the Hard work. Germans had better superchargers. A few of the Anglo Radial engines weren't much.. Nev

[onetrack]

The Germans had better aircraft, but being led by a dictator and criminals, set them up for failure. The Nazis failed to understand the importance of keeping back about 10% of production for spare parts, they built as many aircraft as they could with the parts they produced, and when they broke down, the Luftwaffe had to cannibalise good aircraft to keep the others going.

 

Add in the fact that they used forced labour in their military factories and you could well imagine how many Nazi aircraft failed due to substandard or sabotaged components and parts.

The Allies had enough trouble with a willing workforce, and simple errors in manufacturing, imagine the dramas the Nazi war production factories had.

We lost new aircraft from our factories such as Beaufighters, simply because of tools left inside wings, and the suchlike. This was due to a lack of safety procedures that are standard today - back at the start of WW2, we'd previously built very few aircraft, and aviation knowledge was sadly lacking.

[Jerry_Atrick]

An interesting vid comparing the Spit v BF.109:

 

[onetrack]

There were two other factors in the British wartime aircraft performance that assisted them - 100 octane fuel, and variable-pitch propellors. The Germans never got beyond 87 octane fuel, and this definitely inhibited their performance - although they compensated with higher engine power, and higher top speed in the likes of the Bf-109.

The Bf-109 of the BoB had 1,175HP, and the Spitfire MKIII of the BoB produced 1,030HP - but the use of "emergency boost" to 12psi (for no longer than 5 mins) in the Spitfires, enabled them to produce 1,310HP. This was only possible due to 100 octane fuel.

On the other side of the ledger, the Bf-109 had fuel injection, a vastly superior fuel system to the Spitfires carburettor, which produced engine hesitation under negative G's. The Luftwaffe pilots knew of this Spitfire flaw and the aces tried to ensure the Spitfire was drawn into negative G's in dogfights.

 

There's stories that abound that state the Americans came riding to the rescue of the British with a delivery of 100 octane fuel, just in time for the Battle of Britain - and the fuel made the difference between winning and losing the BoB.

The true story is vastly different. Yes, the Americans can take the kudos for producing 100 octane fuel first (in 1936) - but the British were well abreast of the development, and set about producing the fuel themselves, and ensuring supplies were available from places as far distant as Abadan (Iraq), the Netherlands East Indies, and Trinidad. In addition, the British Govt set the standard in 1937 that all defence aircraft engine deliveries in future, were to be capable of using 100 octane fuel.

 

Adequate supplies of 100 octane were not available until early 1940, and the complete changeover to 100 octane was made in May 1940, just in time for it to used in the retreat from Dunkirk. But the use of 100 octane fuel is also tied in with the fitment of variable pitch propellers to the Spitfires at approximately the same time (June 1940). Thus the two developments combined to substantially improve Spitfire performance.

 

The supply of 100 octane fuel during this period was overwhelmingly from the British sources within the country, and from Abadan, the East Indies, and Trinidad. The Americans contributed less than a quarter of the 100 octane fuel requirements for the British, during this critical phase of WW2. There is an excellent historical review on these subjects below, and it points out that the variable pitch propeller was by far the greatest contributor to the improved performance of the Spitfires.

 

http://www.wwiiaircraftperformance.org/100-octane/Bailey_100-Octane_Fuel.pdf

 

https://en.wikipedia.org/wiki/Supermarine_Spitfire_(early_Merlin-powered_variants)

 

Edited December 29, 2024 by onetrack

[old man emu]

All this aircraft stuff is very interesting, but the movement of the thread away from it original intention is more like the tide flow at Derby WA than the gentle flow of a babbling brook.

[onetrack]

We have indeed, but Christmas 2024 has gone, and thread direction is always a difficult thing to control.

[facthunter]

IF the sugar shaker now has Salt instead how do you subsequently find the SALT?   Nev

[facthunter]

Pssst . It's about the validity of the Label.   Nev

[facthunter]

Happy New Year . 13 hours 35 minutes to go.   Nev

[nomadpete]

2 hours ago, facthunter said:

Happy New Year . 13 hours 35 minutes to go.   Nev

Quick! This is your last chance to do something special in 2024!

[Grumpy Old Nasho]

Doom and gloom here, thunder, overcast, bushfire smoke, breathing it all day yesterday, it looks like they got on top of it (Wollemi National Park), not much smoke today. I hope these are not bad omens for the new year, we've had enough already.

 

Have a nice fireworks night, and a happy new year, with luck.

[facthunter]

  The Have "Crackers" in Darwin in the DRY season too. The LAST WILD FRONTIER. I AM doing something SPECIAL N,M. Pete. I'm Posting HERE!  GON sorry the worst time is about 6 weeks away.. I have NO INVISIBLE means of support SO I can only wish us all the best of luck. Remember the more careful you are the More luck you Have.   Nev

[onetrack]

The gloom here is the State road death toll, it's close to exceeding our worst road toll year, in 2016. They keep wiping themselves out.

 

A lot of it is just plain simple stupidity behind the wheel - Darwinism in action generally, but also resulting in the deaths of innocents as well.

 

I don't see things changing much, just more road cameras, more fines, and more infringement notices for the rest of the population.

 

I thought 2024 was a tumultuous year, I personally think 2025 will be a lot worse. A narcissistic, totally chaotic sociopath, in control of the worlds largest economy - an emboldened Putin who will "win" the Ukraine War as Trump slices support for Ukraine - because Ukraine doesn't contribute to his personal coffers - an emboldened Kim Jong-il who will gain great military assistance from Russia, and up-to-date combat experience for his troops (just what he wanted), and a devious China ever-ready to bend the world to what it wants for itself.

 

Here's hoping more dictatorships fail though, in 2025 - although sometimes it's hard to see what will bring them down. We have to look for the rays of sunshine in the gloom. Happy New Year, everyone!

[Marty_d]

Jeez, thanks OT, I feel so much better now...

 

My 14yo son was out spending his christmas money and came home with this book.  He's been chortling in his room ever since.

Edited December 31, 2024 by Marty_d

[nomadpete]

I think we will all be trying hard to find positive news this coming year.

 

All the best from all of us, to all of you!

[Jerry_Atrick]

Happy new year, everyone! Nev, unless I have missed something, glad your house is safe and hope it stays that way.

 

I am somewhat sanguine re Trump. There's not a lot we can do to change things, so, I will keep abreast of developments, try and work out the outcomes, and adjust accordingly.  There are some things I agree about what he wants to achieve - just not sure about the execution. For example, the US debt to GDP ratio of the US is 1.23:1; in other words, US debt is 123% of GDP. When Italy's was this, they were an economic basklet case of Europe (beathenm I think, only by Greece). That is a debt level that cannot be sustained by any country longer term without somethign eventually giving - tax the hell out of the population, inflate your way out (which is a tax when you think about it), or default.

 

Hope it's a good year...

 

Reolution report from lat year was not too bad.. Reduced energy drink consumption marlkedly.. lost a little weight...  Sadly, house wasn't completed, so one resolution ties over to next year.

 

Although not in my new year's resolution for last year, I havee now been 7 days alcohol free... thanks to the anitbiotics I am currently on. And I don't miss the wine nor beer..  The only things I miss is Campbell's Rutherglen Muscat, but haven't had much of that lately anyway, and some French stuff, Grand Mariner and Cointreu.. So, one of my new year's resolutions is to drop the alocohol consumption markedly.. 1 good Aussie, Kiwi, or Italian red or white a month (oh, and the odd good Beaujolais), and a single GM or C after a dinner once per week.

 

 

 

 

 

[Grumpy Old Nasho]

Happy new year to you to Jerry. The sun is out this morning so we're off to a good start for the new year.

 

Here are some recorded figures from mid-night Dec 31 - Jan 1

 

370 Aussie youngters entered this World since mid-night.

 

I deleted the deaths - don't need gloom today.

 

Australia Population clock (live)

26,978,546	Current population
13,446,173	Current male population (49.8%)
13,532,374	Current female population (50.2%)
370	Births year to date
370	Births today
243	Net migration year to date
243	Net migration today
429	Population growth year to date
429	Population growth today

 

01-01-2025 08:54:07