KLM proposing Flying V
Discussion
More Thunderbirds stuff to enjoy, this time predicted for 2040 takeoff. Bonkers, but I love this type of thing: https://www.sciencealert.com/fuel-efficient-v-plan...
kiethton said:
They look lovely....no idea re. Physics but hope they’re a little faster (as well as more efficient)
The article says it's based around turbofan engines, so it's unlikely to be much faster than current designs. The move from turbojets to turbofans in the 70s had a big impact on efficiency, but the optimal flight speed for turbofans is about 50-100 km/h lower than turbojets. I'm sure there are some more knowledgeable PHers who can add more detail.NNH said:
The article says it's based around turbofan engines, so it's unlikely to be much faster than current designs. The move from turbojets to turbofans in the 70s had a big impact on efficiency, but the optimal flight speed for turbofans is about 50-100 km/h lower than turbojets. I'm sure there are some more knowledgeable PHers who can add more detail.
The move from pure turbojets to turbofans actually happened in the early 1960s. The original DC-8s and 707s had Pratt and Whitney JT3 and JT4 turbojets. As early as 1960s, Boeing were flying the 707-400 with Rolls Royce Conways (which were turbofans) and by 1963 the Pratt and Whitney JT3D turbofan was fitted to 707 and 720 models. The DC-8 followed a similar path.The BAC 1-11 and Trident both had Rolls Royce Spey turbofans. The Boeing 727, 737 and Douglas DC-9 (all 1960s designs) had Pratt and Whitney JT8D turbofans.
All these turbofan engines were classified as low-bypass turbofans. There was a fan at the front and some of the air drawn in by the fan bypassed the central jet engine core and was not burned in the combustion chamber.
The big change was the advent of the high-bypass turbofan, which had a much bigger fan at the front and which meant far more of the air drawn in by the fan bypassed the core. This substantially reduced the exhaust noise and increased the fuel efficiency.
This looks like a variation on the old blended wing body design that NASA and others were examining about 10 years ago.
Although it was more efficient, passengers didn’t like the mock up seating arrangements and it took too long to get everyone out during an evacuation .
I think it’s still being look at for UAVs and military tankers though.
Although it was more efficient, passengers didn’t like the mock up seating arrangements and it took too long to get everyone out during an evacuation .
I think it’s still being look at for UAVs and military tankers though.
NNH said:
The article says it's based around turbofan engines, so it's unlikely to be much faster than current designs. The move from turbojets to turbofans in the 70s had a big impact on efficiency, but the optimal flight speed for turbofans is about 50-100 km/h lower than turbojets.
As Eric says, its the fact they are high bypass ratio turbofan engines.After all, all modern military fast jets have turbofan engines, and lack of speed isn't an issue with those
aeropilot said:
As Eric says, its the fact they are high bypass ratio turbofan engines.
After all, all modern military fast jets have turbofan engines, and lack of speed isn't an issue with those
I agree but, they generally also use reheat to go faster (and convergent / divergent nozzles to stay faster with the reheat deselected for those that can supercruise!)After all, all modern military fast jets have turbofan engines, and lack of speed isn't an issue with those
Turbofan or not turbofan is not the issue. The Tu-144 had turbofans - Concorde didn't. Some modern turbofan fighters can cruise supersonically without reheat.
The blended body design has been touted for at least the past four decades. NASA has even test flown a remote controlled scale model concept vehicle.
That was around 20 years ago.
The blended body design has been touted for at least the past four decades. NASA has even test flown a remote controlled scale model concept vehicle.
That was around 20 years ago.
Eric Mc said:
Turbofan or not turbofan is not the issue. The Tu-144 had turbofans - Concorde didn't. Some modern turbofan fighters can cruise supersonically without reheat.
The blended body design has been touted for at least the past four decades. NASA has even test flown a remote controlled scale model concept vehicle.
That was around 20 years ago.
The X-48B first flew 12 years ago, the X-48C 7 years ago.The blended body design has been touted for at least the past four decades. NASA has even test flown a remote controlled scale model concept vehicle.
That was around 20 years ago.
Eric Mc said:
Turbofan or not turbofan is not the issue. The Tu-144 had turbofans - Concorde didn't. Some modern turbofan fighters can cruise supersonically without reheat.
They can't get there without reheat though can they? And when they're there, they need con Di nozzles :-) I suspect they way airliners will try to go is turbo genset + ducted fans ie neither turbofan or turbojet If they crack the electric distribution system.
Mave said:
They can't get there without reheat though can they? And when they're there, they need con Di nozzles :-)
I suspect they way airliners will try to go is turbo genset + ducted fans ie neither turbofan or turbojet If they crack the electric distribution system.
I'm pretty sure there are some aircraft that can attain supersonic speeds without the need for reheat.I suspect they way airliners will try to go is turbo genset + ducted fans ie neither turbofan or turbojet If they crack the electric distribution system.
Also, most modern fighters that have reheat are also turbofan powered - so using a turbofan does not preclude the use of an afterburner.
However, nobody is claiming a blended wing design will be supersonic. It's all about fuel efficiency, load and range - as these are what matters to airlines.
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