More efficient jet engine design
- Thread starter Exhaustgases
- Start date
Can’t help but think of Indiana Jones.
Bird impacts are going to be really grisly.
Open fan architecture has been around for at least 40 years. Unducted Fan, as it’s also known.
Nobody has bought it, yet. It’s really noisy and doesn’t just “bolt on” to most underwing engine mounts, severely limiting the applications to, well, airplanes that are either out of production, or haven’t been built yet.
Most of this paper is about “the way forward” and “partnering” - so, in software, you would call this “vaporware”. The powerplant has been tested (see the 1988 installation) but no airplanes have been built with it since that test. NO actual design for retrofit to existing airframes exists.
This paper is a glitzy set of promises about how this engine manufacturer “stands ready” to “partner”.
So, yeah, I will believe it when it shows up on the ramp.
Nobody has bought it, yet. It’s really noisy and doesn’t just “bolt on” to most underwing engine mounts, severely limiting the applications to, well, airplanes that are either out of production, or haven’t been built yet.
Most of this paper is about “the way forward” and “partnering” - so, in software, you would call this “vaporware”. The powerplant has been tested (see the 1988 installation) but no airplanes have been built with it since that test. NO actual design for retrofit to existing airframes exists.
This paper is a glitzy set of promises about how this engine manufacturer “stands ready” to “partner”.
So, yeah, I will believe it when it shows up on the ramp.
At ERAU, Ken Rowe was one of my professors. He's the guy that defected from NK in a Mig. I made a handful of afterburning gas turbine engines from scratch, and we worked together to design a plastic bladed turbofan, driven by a small gas turbine, designed to launch a glider, a "college project" that was never built. Of course, I got an "A" in his classes.
Back then the Unducted Fan had just come about, and my design changed from a ducted fan to a UDF. The idea was to use variable pitch Dupont Zytel blades (nylon with fiberglass) and a direct drive gearbox. Tip speeds being limited to about M 0.8 or so. Maximizing efficiency, while minimizing noise.
Fast forward to today, I'm retired and would like to finally build my project. With some modern changes. No need for variable pitch blades anymore. And a staggered set of blades for noise reasons.
The fan can simply change RPM as needed. The stators behind the fan need to be variable to straighten the flow.
Take a look at how the 10 fan blades are staggered (in pairs). This prevents resonance.
Anyway, I really like the idea of a UDF, and the noise issue may in fact be manageable by low RPM, high pitch operation at low altitudes.
Back then the Unducted Fan had just come about, and my design changed from a ducted fan to a UDF. The idea was to use variable pitch Dupont Zytel blades (nylon with fiberglass) and a direct drive gearbox. Tip speeds being limited to about M 0.8 or so. Maximizing efficiency, while minimizing noise.
Fast forward to today, I'm retired and would like to finally build my project. With some modern changes. No need for variable pitch blades anymore. And a staggered set of blades for noise reasons.
The fan can simply change RPM as needed. The stators behind the fan need to be variable to straighten the flow.
Take a look at how the 10 fan blades are staggered (in pairs). This prevents resonance.
Anyway, I really like the idea of a UDF, and the noise issue may in fact be manageable by low RPM, high pitch operation at low altitudes.
UDF engines can have bypass ratios of more than 20 to 1. Unfortunately, the discharge velocity is limited to the speed of sound at the temperature the plane operates at. So pushing an airliner to transonic speeds with a UDF is more than a little difficult.
Aircraft speeds would be reduced, and being that more than half of flights have a headwind component, the time aloft would be greatly increased. Fuel specifics don't tell the entire story.
Remember that a crosswind is a headwind, as an aircraft must remain on course.
In other words, a case can be made for maximizing transport aircraft speeds. This is where a UDF falls short.
Aircraft speeds would be reduced, and being that more than half of flights have a headwind component, the time aloft would be greatly increased. Fuel specifics don't tell the entire story.
Remember that a crosswind is a headwind, as an aircraft must remain on course.
In other words, a case can be made for maximizing transport aircraft speeds. This is where a UDF falls short.
