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Air Force funds ‘blended wing body’ design for long-range, fuel-efficient flight

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Re: Air Force funds ‘blended wing body’ design for long-range, fuel-efficient flight

#31

Earlier quoted context omitted.

If this is the only practical solution for hydrogen fuelled aircraft, then it can't fail in passenger markets because there will be no other alternative to compete against once kerosene is too ecologically taxed.

Is there even a hydrogen turbojet engine?

Maybe not in service, but it's been done: https://www.reuters.com/business/aerospace-defense/rolls-roy...

Re: Air Force funds ‘blended wing body’ design for long-range, fuel-efficient flight

#32

Earlier quoted context omitted.

If this is the only practical solution for hydrogen fuelled aircraft, then it can't fail in passenger markets because there will be no other alternative to compete against once kerosene is too ecologically taxed.

Is there even a hydrogen turbojet engine?

Afaik it's one of the three H2 airframe options Airbus is pursuing.

https://www.airbus.com/en/innovation/low-carbon-aviation/hyd...

The general idea is to use liquid H2, like the old KN-88 design.

https://en.wikipedia.org/wiki/Kuznetsov_NK-88

Re: Air Force funds ‘blended wing body’ design for long-range, fuel-efficient flight

#33
post #4

It used to be said this would fail in passenger markets because windows. The reality of long haul travel these days is that windows are really only "I can lean here" choices which restrict access to the aisle, for any trans-oceanic journey. For domestic flights, I am sure there are window seat aficionado who will continue to pay for window in flight. For everyone else, and by current seating maps there are a LOT more…

If this is the only practical solution for hydrogen fuelled aircraft, then it can't fail in passenger markets because there will be no other alternative to compete against once kerosene is too ecologically taxed.

If you can make carbon-neutral hydrogen, you can combine it with atmospheric CO2 to make synthetic hydrocarbons (or methanol) that are carbon-neutral. There's an energy cost to doing this, but I'm willing to bet it far outweighs the costs of running an airliner on hydrogen.

Re: Air Force funds ‘blended wing body’ design for long-range, fuel-efficient flight

#34
post #4

It used to be said this would fail in passenger markets because windows. The reality of long haul travel these days is that windows are really only "I can lean here" choices which restrict access to the aisle, for any trans-oceanic journey. For domestic flights, I am sure there are window seat aficionado who will continue to pay for window in flight. For everyone else, and by current seating maps there are a LOT more…

> If it has to be a freight or logistics/materiel/fuel aircraft for the forces before general service, so be it. The challenge for that is economic: those use cases which are generally filled with adaptations of older generation aircraft at the moment probably don't pay back the R&D costs of the programme. Especially since a viable civil aircraft programme also involves worldwide line maintenance capability, a liquid…

> Military use involves completely different economics, but for related reasons the anticipated greater fuel efficiency is rarely a big deal for the military.

I think this assumption is wrong, for airplanes. Higher fuel efficiency means longer range for the same amount of fuel, so it's an increase to range for the same weight carried (or an increase in weight carried to the same range, presumably). I think this is extremely important to the military.

Re: Air Force funds ‘blended wing body’ design for long-range, fuel-efficient flight

#35
post #25
post #18

Nice. NASA and Airbus have both flown blended-wing unmanned test aircraft. Not sure what role this serves for the USAF. It's a transport. Wider loads? Stealth? The US has had total air superiority in every conflict since the Korean War. That's over. The Ukraine war makes it clear. Against a competent opponent, most of what flies will die. There are just too many man-portable and truck-mounted systems that can take do…

Russia would fall like Iraq if we were to attack. Their ground-based anti-air would be hit as soon as even one missile is fired, every radar would be hit within minutes of powering on, their aircraft wiped out as soon as they were within range. With air supremacy we'd be able to fire a precision strike on every piece of active artillery and supply truck. They'd be left with nothing but men starving in trenches and ru…

The is the kind of delusional thinking that has NATO forcing Ukraine to use western strategy and then getting slaughtered for it.

The US has never defeated a peer army since WW2, in which the USSR did most of the work. Russia has fifth gen fighters, the S400, and very capable EW and artillery. To pretend they would roll over is pure fantasy.

Re: Air Force funds ‘blended wing body’ design for long-range, fuel-efficient flight

#36
post #25
post #18

Nice. NASA and Airbus have both flown blended-wing unmanned test aircraft. Not sure what role this serves for the USAF. It's a transport. Wider loads? Stealth? The US has had total air superiority in every conflict since the Korean War. That's over. The Ukraine war makes it clear. Against a competent opponent, most of what flies will die. There are just too many man-portable and truck-mounted systems that can take do…

Russia would fall like Iraq if we were to attack. Their ground-based anti-air would be hit as soon as even one missile is fired, every radar would be hit within minutes of powering on, their aircraft wiped out as soon as they were within range. With air supremacy we'd be able to fire a precision strike on every piece of active artillery and supply truck. They'd be left with nothing but men starving in trenches and ru…

Ukraine used to be one of the most prolific black market military arms dealers.

We should absolutely avoid sending Ukraine any modern equipment. As soon as the war is over, they'll sell it on the black market to countries that will gladly reverse engineer what we've built.

And as an aside, I have no interest in funding proxy wars with my tax dollars. Let's not return to a Cold War era. Entering this conflict was absolutely absurd.

Re: Air Force funds ‘blended wing body’ design for long-range, fuel-efficient flight

#37
post #25

Earlier quoted context omitted.

Russia would fall like Iraq if we were to attack. Their ground-based anti-air would be hit as soon as even one missile is fired, every radar would be hit within minutes of powering on, their aircraft wiped out as soon as they were within range. With air supremacy we'd be able to fire a precision strike on every piece of active artillery and supply truck. They'd be left with nothing but men starving in trenches and ru…

The is the kind of delusional thinking that has NATO forcing Ukraine to use western strategy and then getting slaughtered for it. The US has never defeated a peer army since WW2, in which the USSR did most of the work. Russia has fifth gen fighters, the S400, and very capable EW and artillery. To pretend they would roll over is pure fantasy.

They wouldn't roll over but they would get crushed. Our BVR, cyber, and stealth capabilities far exceed theirs.

In any case, we will never fight a hot war with a nuclear armed country ever again. Nuclear deterrence works, and the nuclear bomb has thankfully ended modern warfare between nuclear-armed countries.

The era of superpowers sending men off to die is over, at least between nuclear-armed countries (but not so much between a nuclear and non-nuclear country.)

Re: Air Force funds ‘blended wing body’ design for long-range, fuel-efficient flight

#38
post #18

Nice. NASA and Airbus have both flown blended-wing unmanned test aircraft. Not sure what role this serves for the USAF. It's a transport. Wider loads? Stealth? The US has had total air superiority in every conflict since the Korean War. That's over. The Ukraine war makes it clear. Against a competent opponent, most of what flies will die. There are just too many man-portable and truck-mounted systems that can take do…

> The US has had total air superiority in every conflict since the Korean War. That's over. The Ukraine war makes it clear. Against a competent opponent, most of what flies will die.

Not sure how you work that out. The state that spent half a century focusing on air defence to take out the USAF hasn't even substantially reduced the pathetically small and outdated fixed wing capability of the Ukrainian air force, and neither side has done much damage to the other side's airborne logistics, which is where this would fit. It's not been a great war for helicopters, but neither this project nor the US fighter capability that their superiority rests on is going anywhere close to frontline portable air defence systems.

Re: Air Force funds ‘blended wing body’ design for long-range, fuel-efficient flight

#39
post #30

Earlier quoted context omitted.

BWB aircraft have a few more issues than just a lack of window seats. They require a higher angle of attack on take-off and landing, and, with passengers sitting much further from the centerline of the aircraft than on a conventional design, passengers are subject to much more g-forces during roll maneuvers. The second issue can be mitigated by avoiding rolling the aircraft and/or by performing less aggressive rolls,…

I wonder if you could tilt everyone's seats forward during takeoff and landing. I've seen very high density seating in the far east where people are virtually standing. Maybe the seats could start off that way, stay that way through takeoff and ascent, then gently lower to a normal posture in level flight.

Like the pendolino trains? Perhaps it could work, but will make the seats more complicated.

Re: Air Force funds ‘blended wing body’ design for long-range, fuel-efficient flight

#40

Earlier quoted context omitted.

> If it has to be a freight or logistics/materiel/fuel aircraft for the forces before general service, so be it. The challenge for that is economic: those use cases which are generally filled with adaptations of older generation aircraft at the moment probably don't pay back the R&D costs of the programme. Especially since a viable civil aircraft programme also involves worldwide line maintenance capability, a liquid…

> Military use involves completely different economics, but for related reasons the anticipated greater fuel efficiency is rarely a big deal for the military. I think this assumption is wrong, for airplanes. Higher fuel efficiency means longer range for the same amount of fuel, so it's an increase to range for the same weight carried (or an increase in weight carried to the same range, presumably). I think this is ex…

It's not completely useless, but the US military's existing transport aircraft are not exactly pushing the boundaries of fuel consumption. A regular 777 freighter will get quite a bit further. Ultimately the military don't care about the cost, have many refuelling options, and are relying on much shorter range aircraft in other aspects of any conflict. Plus unlike other areas of aviation, if you solve a range problem with a bigger fuel tank, you don't get beaten to death by the bean counters.

That's quite different from an airline, where a 20% saving in their largest expense against a 3% margin in a price competitive industry is game changing

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