61–70 of 114 posts
The KC-46 program has not gone swimmingly. I'm curious how they think they're going to get a demonstrator flying in 5 years when they can't get a tanker that's based on an existing production airframe flying on schedule. https://en.m.wikipedia.org/wiki/Boeing_KC-46_Pegasus
The KC-46 program has not gone swimmingly. I'm curious how they think they're going to get a demonstrator flying in 5 years when they can't get a tanker that's based on an existing production airframe flying on schedule. https://en.m.wikipedia.org/wiki/Boeing_KC-46_Pegasus
I wouldn't be surprised if its got a heavy use of composites as well, in order to reduce he number of total parts. For the ACCA, they had 300 structural parts vs 3,000 metallic and 4,000 mechanical fasteners vs 40,000 otherwise.
https://www.lockheedmartin.com/en-us/news/features/history/a...
I thought the issue was that it was hard to pressurize a blended wing design. All pressurized planes are pretty much a tube shape, which are easier to design to endure metal fatigue and lots of pressurization cycles. The skin of an airliner is 2-4mm thick, I think you would need a substantially thicker skin for this shape.
But do you need to pressurize it? Only the crew space needs that which could be a small/short tube in the middle right behind (and including) the cockpit. The fuel tanks don’t care. They’re not pressurized on a normal design. The cargo may not need it either.
Earlier quoted context omitted.
> fuel doesn't care about the bobbing up and down Maybe the fuel doesn't care, but the flight crew certainly will care about a large oscillating mass constantly changing the aircraft's center of mass.
Baffles are typically used to control this, even in conventional aircraft fuel tanks. It's a non-issue.
Earlier quoted context omitted.
It wasn't Boeing that was trying to save money themselves- it was Boeing trying to save airlines money. There are hundreds of thousands of people today who can fly a 737, and mechanics who can fix a 737, etc. The airlines wanted to get the better fuel efficiency from modern engines on a plane that everyone already knew how to fly and fix. Boeing actually started with a clean sheet design, tried to pitch it to airline…
“Give us a 737 but more crashy” is also not what their customers really wanted. There were surely more possibilities available than just the two extremes of “737 but crashes more” and “tiny Concorde.”
A tanker is a good fit for a blended wing body. Fuel efficiency is important for that mission, fuel tanks can be easily adapted to the odd shape (compared to cargo), and fuel doesn't care about the bobbing up and down in turns that comes from the wide hull shape (compared to passengers who don't like about that). Reconnaissance would work too.
> fuel doesn't care about the bobbing up and down Maybe the fuel doesn't care, but the flight crew certainly will care about a large oscillating mass constantly changing the aircraft's center of mass.
Earlier quoted context omitted.
It wasn't Boeing that was trying to save money themselves- it was Boeing trying to save airlines money. There are hundreds of thousands of people today who can fly a 737, and mechanics who can fix a 737, etc. The airlines wanted to get the better fuel efficiency from modern engines on a plane that everyone already knew how to fly and fix. Boeing actually started with a clean sheet design, tried to pitch it to airline…
“Give us a 737 but more crashy” is also not what their customers really wanted. There were surely more possibilities available than just the two extremes of “737 but crashes more” and “tiny Concorde.”
Everything stems from Boeing taking this deal. Within the constraints of the 737 type certification: more efficient engines are larger, larger engines must move forward, forward engines change flight characteristics, flight characteristics must be augmented to maintain certification.
So you are correct that Boeing had choices other than "crashy 737", but that choice was between throwing billions away to Airbus and the crashy 737.
The KC-46 program has not gone swimmingly. I'm curious how they think they're going to get a demonstrator flying in 5 years when they can't get a tanker that's based on an existing production airframe flying on schedule. https://en.m.wikipedia.org/wiki/Boeing_KC-46_Pegasus
Wow, what's a TL;DR of the problems? The KC-767 seems to be working fine, one has been flying over my house at least once a week since I was a teenager
https://www.thedrive.com/the-war-zone/40821/kc-46as-long-tro...
I thought the issue was that it was hard to pressurize a blended wing design. All pressurized planes are pretty much a tube shape, which are easier to design to endure metal fatigue and lots of pressurization cycles. The skin of an airliner is 2-4mm thick, I think you would need a substantially thicker skin for this shape.
But do you need to pressurize it? Only the crew space needs that which could be a small/short tube in the middle right behind (and including) the cockpit. The fuel tanks don’t care. They’re not pressurized on a normal design. The cargo may not need it either.