Linked Questions

47
votes
3answers
21k views

Why is the Tu-95 so efficient despite having propellers that spin faster than the speed of sound?

I've ready many, many times that propellers are not efficient near the speed of sound because it's so hard to get a tip-speed above Mach 1. Then I came across this: It's the Tu-95 "Bear", a ...
8
votes
7answers
8k views

Why are contra-rotating jet engines so rare?

Why are contra-rotating jet engines so rare? Such a jet engine would have contra-rotating turbines, or contra-rotating compressors, or both. In fact I cannot think of even one aircraft that has this. ...
27
votes
1answer
14k views

Is there any equation to bind velocity, thrust and power?

I am designing a remote controlled airship. I will tune it so that the lift given by Archimedes' Principle will exactly balance the weight of all the structure. It will be propelled by brushless ...
16
votes
3answers
7k views

Is it possible to drive a prop directly from a jet engine without a gearbox?

I'm studying turbojets, turbofans, and turboprops. I can see that, for the latter engine configuration, a gearbox is necessary so that the propeller rotates at a lower velocity than the main ...
18
votes
2answers
4k views

What prevents jet engine designs with larger bypass ratios?

In commercial aviation, it seems jet engines grow and bypass ratio increase with newer engines. Here is some examples: 1963: bypass ratio: 0.96 (P&W JT8D) 1970: bypass ratio: 5.0 (P&W JT9D) ...
10
votes
2answers
6k views

What are the limitations in adoptions of GTF (Geared Turbofan) technology?

The only recent engine using GTF technology is the PW1000G, however some old designs like ALF502 or TFE731 use this technology. I understand the basic concept of the benefit obtained by the engine ...
13
votes
1answer
6k views

What is a "high-bypass geared turbofan," and why is it so much more efficient?

According to the article Bombardier’s CSeries Gamble Is Facing Longer Odds, this new plane from Bombardier uses a new engine technology that will improve efficiency over its rival 737 series and A320 ...
10
votes
1answer
1k views

Is ultrasonic noise from small turbines painful to pets?

A question on another SE site prompted me to search for 'Aircraft engines untrasonic noise dogs', but with not much success. The OP's dog barked like crazy at turboprops, but was not bothered at all ...
3
votes
3answers
7k views

What does RPM mean in a propellor aircraft, compared to a jet aircraft? [closed]

What is the practical significance of speed RPM in a propeller aircraft for a pilot? I am not able to correlate it with RPM in jet engines?
0
votes
2answers
91 views

In general, what are the RPM ranges/differences between the various compression stages on a 2 or 3 spool (LP,IP,HP) turbojet/fan engine?

I have a general interest in jet engines and am pretty new to the topic so I wanted to toss this question into the wind as I don't have any previous experience or knowledge to pull from and haven't ...