Linked Questions

69 votes
10 answers
94k views

Why do jet engines get better fuel efficiency at high altitudes?

I'm told that this is true, but I can't imagine why. It seems like the fact that there is less air would make the engines less efficient... But that probably just shows how little I know about jet ...
Jae Carr's user avatar
  • 24.2k
40 votes
9 answers
34k views

Why increase the number of cylinders in an engine instead of increasing their volume?

I've been reading about WW2 planes lately. Some of them have 12 or even more pistons in their engines. But if your goal is to increase power, why would you add more pistons instead of simply ...
DrZ214's user avatar
  • 17.8k
24 votes
6 answers
10k views

In what way are the Concorde's engines considered efficient?

The Concorde is powered by a bunch of Rolls-Royce/Snecma Olympus 593 turbojet engines. Much has been said about how efficient they are at speed, and the fact that they allow long-range cruise at Mach ...
ithisa's user avatar
  • 1,702
12 votes
4 answers
8k views

Which engine is more financially economical to operate, a turboprop or gasoline engine?

I've seen a discussion about this somewhere before. I'm aware that there's no real way to calculate this. So rather then comparing weight and volume for efficiency, let's compare prices. Which engine ...
Mateo's user avatar
  • 746
11 votes
2 answers
25k views

How can I calculate the fuel consumption of an Airbus 320-200 at various loads?

I want to know: What is the fuel consumption of an Airbus A320-200 - 180 Seats, at 100% load factor for a distance of 2000 km? What is the fuel consumption of an Airbus A320-200 - 180 Seats, at 80% ...
user3551's user avatar
  • 119
17 votes
3 answers
3k views

Can the plane Celera 500L be eight times more fuel efficient than a jet of similar size and capacity?

Celera 500L (see Otto Aviation site for more details) is a plane with a single propeller powered by a piston diesel engine. The constructor claims it is 8 times more fuel efficient than a jet of about ...
Robert Werner's user avatar
19 votes
1 answer
20k views

Which jet engines have the highest thermal efficiency?

Some automakers (Mercedes-Benz, Toyota) have recently been making news about the improved thermal efficiency of their engines, stating that they reached the 50% mark. I was wondering if it was the ...
clueless007's user avatar
8 votes
5 answers
2k views

Why aren’t diesel piston engines used on aircraft like the Saab 340 or L-410?

In contrast to this question (link), I would like to know the opposite - why diesel piston engines aren't used on aircraft with comparable role and configuration to Saab 340, L-410, ATR-42? There's ...
Electric Pilot's user avatar
10 votes
1 answer
4k views

If the efficiency of a turbofan engine is 35%, where does the rest of the fuel energy go?

There have been a couple of questions on this site about the efficiency and propulsive power of turbine engines (here, here, here). In a high bypass turbofan engine, what are the losses in the ...
Koyovis's user avatar
  • 61.8k
2 votes
1 answer
260 views

How is take-off power defined?

In a recent post it could be read that by definition, turbofans do not produce power in the static case (at velocity zero). The statement could be a bit confusing since turbofans and propeller engines ...
Koyovis's user avatar
  • 61.8k