the most ironic situations of WW II

[Chogy]

Actually, designing a plane with two huge 100,000 hp turbines, is rather stupid, because the plane has to be able to takeoff if one turbine fails, so if you use three 50,000 hp turbines and one fails it takes off the same as if one of two 100,000 hp turbines fail. Turbines are inefficient when operating at low speed (unlike piston engines), so using two turbines at low capacity after take off is less efficient than stopping one of three turbines and using the other two at 85% capacity.

With all due respect, you have no idea what you are talking about. Why do you think airlines prefer, and major manufacturers create, huge twin jets like the Boeing 777 and Airbus A-300?

They are much more efficient and economical to operate than 3 or 4 engine jets. The DC-10, MD-11, L-1011 are all pretty much dead, taken out of service.

 

[samjok]

Hi Chogy,
Just because Boeing and Airbus build something does not mean it is the optimum way. Dozens of planes designed and bult by these companies have crashed because of extremely stupid design mistakes and both companies will go bankrupt as soon as Japan or China make the huge investment required to design their own planes.
The 777 and A-300 are more efficient because they have stronger, stiffer and lighter materials, more modern and efficient engines (not because they are bigger, just because they have more efficient fans, turbine blades, higher temperature materials, etc,) and are slightly more aerodynamic, not because they have two engines. If you take those planes and put 3 turbines, each with half the power of each of the 2 turbines in Boeing´s plane, the 3 engine plane is lighter and uses less fuel when cruising with two turbines at a higher percentage of their maximum power than two huge engines at a low power setting. It also produces a much milder blast, smaller eccentric force if one engine fails (smaller vertical stabilizer, etc,). Maintenance is a little more expensive but safety and fuel efficiency are enhanced. Given the steep increase in fuel costs, the paramount importance of curbing green house gases and of safety. It was definitely stupid to use 2 huge engines.
The saddest thing is that the airplane manufacturers forced the turbine manufacurers to come up with these monsters that require a huge investment to produce a few units. A turbine with half the hp requires a much smaller investment to develop and produce and is more profitibale when making 3 instead of two (the plane costs a little more but the fuel and insurance savings more than make up for that).

 

[SQ8]

Hi Chogy,
Just because Boeing and Airbus build something does not mean it is the optimum way. Dozens of planes designed and bult by these companies have crashed because of extremely stupid design mistakes and both companies will go bankrupt as soon as Japan or China make the huge investment required to design their own planes.
The 777 and A-300 are more efficient because they have stronger, stiffer and lighter materials, more modern and efficient engines (not because they are bigger, just becasue they have more efficient fans, turbine blades, higher temperature materials, etc,) and are slightly more aerodynamic, not because they have two engines. If you take those planes and put 3 turbines, each with half the power of each of the 2 turbines in Boeing´s plane, the 3 engine plane is lighter and uses less fuel when cruising with two turbines at a higher percentage of their maximum power than two huge engines at a low power setting. It also produces a much milder blast, smaller eccentric force if one engine fails (smaller vertical stabilizer, etc,). Maintenance is a little more expensive but safety and fuel efficiency are enhanced. Given the steep increase in fuel costs, the paramount importance of curbing green house gases and of safety. It was definitely stupid to use 2 huge engines.

How will you ensure that the power to weight ratio of one of the three smaller engines is higher than that of one larger engine?
How will they consume less fuel.
Leave aside airlines.. The F-18 uses two Ge-404 engines to the F-16's one. .. with the two providing similar T/W ratios for their aircraft.. yet it consumes fuel faster than the PW F-100.
So more is better or lighter is never a rule.. and never will be a rule.

Moreover, current civilian engines are a lot more safer than the engines of say 1950..
and almost all twin engines jets are certified for long duration ETOPS.
And aircraft too are now much more capable of handling engine failures and the problems that come with them.
A third engine not running.. or at idle.. is dead weight.. nothing more inefficient than dead weight.

Your first paragraph is judgmental but on a wafer thin base, what recorded arguments do you have on Boeing and Airbus not being efficient designers.. if you are taking about crash rates of aircraft designed and built in the 60's or 70's then you should compare the crash rates of Russian jets as well. Current Boeing and Airbus aircraft have a lot of distinctions of being able to make it to safety after a failure when other jets may not have made it.

 

[samjok]

Another ironic situation:
Mussolini invading Greece at the worst possible time, when he had just dismissed 600,000 reservists to go home for the autumn harvest and lots of troops and vehicles in Libya but in Albania he had just 8 divisions (which had just been reduced from 3 to 2 battallions) and 107 trucks. So the Greeks beat the hell out of the Italians and Mussolini would have lost Albania, his only source of cheap oil had not Hitler run to his aid.
Then Churchill sending all his troops to Greece when the Germans were already there and the situation was hopeless.
Had Churchill been a slightly better strategist, instead of launching operation Compass (which he never expected to be so successful), he should have invaded extremely poorly defended Sicily when there were hundreds of thousands of Italian troops in Libya and Greece. Sicily was ideal territory for a British invasion with its huge coast from which the artillery of the British battleships can reach 30 km inland. The airplanes could be launched from Malta and the carriers (they launched Hurricanes in Norway).

 

[samjok]

Hi Santro,
1) Making three 50,000 hp lighter than two 100,000 hp engines is a no brainer.
2) Do you unbderstand the fact that while a piston engine is very efficient over a wide range of power settings, a turbine's efficiency drops rapidly as power output decreases? If you do then you will understand that 2 small engines at 85% power (the third one is not operating) are more efficient than two huge engines at 42.5 % power.
3) A small idle engine is less dead weight that using 42.5 % of 2 huge engines.
4) I am talking about crashes occurring in the 90s and in the 21st century because of extremely stupid mistakes that cost these companies and airlines billions to correct.

 

[SQ8]

Hi Santro,
1) Making three 50,000 hp lighter than two 100,000 hp engines is a no brainer.
2) Do you unbderstand the fact that while a piston engine is very efficient over a wide range of power settings, a turbine's efficiency drops rapidly as power output decreases? If you do then you will understand that 2 small engines at 85% power (the third one is not operating) are more efficient than two huge engines at 42.5 % power.
3) A small idle engine is less dead weight that using 42.5 % of 2 huge engines.
4) I am talking about crashes occurring in the 90s and in the 21st century because of extremely stupid mistakes that cost these companies and airlines billions to correct.

1. Yet not many have achieved the power to weight ratio's of the bigger engines.
2. Which is why modern airliners are powered by Turbofans.. not pure turbines. Also, the efficiency improves under differing altitude and temperature conditions. Offering advantages of both speed and fuel efficiency that a piston cannot match.
3. I fail to see how.
4. Mistakes such as?

 

[samjok]

Hi Santro,
Of course we are talking only about turbofans, there is no such thing as just turbines, there are turbojets or turboprops or turbofans. We have only talked about turbofans when we refer to turbines.
At any altitude, speed, temperature, plane load, etc, a turbine operating at low power burns more fuel per unit thrust than one operating at high power.
Like I said, the problem of using 2 engines is that if one engine fails, the other one has to be able to lift the plane during take off (a design specification), so you have to have a lot of excess power. Even if you have a slightly lower power to weight ratio, if you need only 75% of the total power (because if one engine fails you still have 50% of the power) you come out ahead. Not to mention the fact that because you are using less fuel and a smaller vertical stabilizer, the plane is lighter and more aerodynamic at takeoff.
Watch the National Geographic series Mayday for the long list of incredibly stupid design mistakes.

Moreover, the much reduced and better distributed blast from the 3 smaller engines causes less turbulence for subsequent planes at the airport. Passengers experience less noise with an engine in the tail and two much smaller ones under the wings and if the plane crashes the engines are less likely to destroy a building and kill a lot of people or if the plane alights in water the engines are less likely to break off, like they did in the case where gueese stopped the two engines and the plane alit in water and both engines broke off.
Finally the smaller engines and especially the one in the tail are less likely to suck up rocks, bolts, etc, from the runway and birds in flight.

For those who believe that Airbus is a smart and efficient company, look at the logic of building parts all over Europe and sending them to a small town in France, where the huge trailers have to wind through the narrow streets, etc, Only a very advanced and brilliant company that can´t be competitive without huge subsidies can do that (Boeing also receives huge subsudies from the military as its recent law suit against Airbus for receiving subsidies brought out to light).

 

[Chogy]

Samjok, with respect, you are simply wrong in many ways.

Do you unbderstand the fact that while a piston engine is very efficient over a wide range of power settings, a turbine's efficiency drops rapidly as power output decreases? If you do then you will understand that 2 small engines at 85% power (the third one is not operating) are more efficient than two huge engines at 42.5 % power.

Let me ask you a question... regardless of the number of turbine engines operating, what percentage power do you think they cruise at? 40%? 90%?

Another question... do you honestly believe a 777 with four smaller engines will be more economical to operate than two large engines? If so, explain.

 

[samjok]

I already answered the first question and I spoke about 3 not 4 engines.

 

[SQ8]

I already answered the first question and I spoke about 3 not 4 engines.

OK , answer the one about turbine engines? What is the Cruise N1 and N2?

 

[samjok]

Hi Santro,
N1 and N2 refer to rotational speed not to power output or thrust, which is what I am talking about. If you reduce the rotational speed slightly power output drops considerably.