Variable Geometry
Discussion
Variable Geometry wings were the preferred design option for a number of combat aircraft conceived and designed in the late 60's to mid 70's (F-14, F-111, B-1, Tornado, Lots of Russian Stuff...) but hasn't been chosen for the generation of aircraft that replaced them.
What changed ? Improvements in material science ? Fly by wire technology ?
What changed ? Improvements in material science ? Fly by wire technology ?
As I understand it, the increased weight and complexity, combined with FBW systems improving low speed handling meant the advantages no longer outweighed the disadvantages. All engineering is a series of compromises.
But I await a better (or more specific) explanation from someone better informed.
But I await a better (or more specific) explanation from someone better informed.
I also read it was better wing design as well as FBW. Not sure how true this but I also heard that fighter pilots didn't like the idea that an opponent could judge their intentions by how far the wings were swept, but Western swing wing aircraft were never really intended for dogfighting anyway.
Weight is always the 'enemy' of flight. A point frequently lost on the people writing military specifications, where very often the prototype needs bigger engines, more fuel etc etc.
If you have a look at the massive structure that supports the wing pivot on a Tornado it looks like it belongs on a railway engine, massive and heavy and then you have the actuators and then a bunch of linkages to keep the pylons aligned and the controls connected whilst the wing moves.
Then you have fly by wire, which can make stuff brick shaped flyable! I suspect the pivot arrangements were the heaviest element of the entire structure. Simply(!) replaced with computing power.
If you have a look at the massive structure that supports the wing pivot on a Tornado it looks like it belongs on a railway engine, massive and heavy and then you have the actuators and then a bunch of linkages to keep the pylons aligned and the controls connected whilst the wing moves.
Then you have fly by wire, which can make stuff brick shaped flyable! I suspect the pivot arrangements were the heaviest element of the entire structure. Simply(!) replaced with computing power.
The Tornado had fly by wire! As did the F1-11.
However, the huge computing power now available means that designers no longer feel held back by the computers.
Back in the mid-80s at Marham I was sat in a Land Rover waiting for the lights to turn green when a series of Tornados came in to land, wings swept. They were training, just in case. I think they were landing at about 240kts, and the rapid, constant corrections by the CSAS system were clear to see as the tailerons fidgeted away. No pilot could do that.
However, the huge computing power now available means that designers no longer feel held back by the computers.
Back in the mid-80s at Marham I was sat in a Land Rover waiting for the lights to turn green when a series of Tornados came in to land, wings swept. They were training, just in case. I think they were landing at about 240kts, and the rapid, constant corrections by the CSAS system were clear to see as the tailerons fidgeted away. No pilot could do that.
Tony1963 said:
The Tornado had fly by wire! As did the F1-11.
However, the huge computing power now available means that designers no longer feel held back by the computers.
Back in the mid-80s at Marham I was sat in a Land Rover waiting for the lights to turn green when a series of Tornados came in to land, wings swept. They were training, just in case. I think they were landing at about 240kts, and the rapid, constant corrections by the CSAS system were clear to see as the tailerons fidgeted away. No pilot could do that.
This is another one of those anecdotes that I love hearing about. Very interesting. Cheers However, the huge computing power now available means that designers no longer feel held back by the computers.
Back in the mid-80s at Marham I was sat in a Land Rover waiting for the lights to turn green when a series of Tornados came in to land, wings swept. They were training, just in case. I think they were landing at about 240kts, and the rapid, constant corrections by the CSAS system were clear to see as the tailerons fidgeted away. No pilot could do that.
heisthegaffer said:
This is another one of those anecdotes that I love hearing about. Very interesting. Cheers
A pleasure!These threads are good for shaking the memories from the back of my mind. When there’s no nastiness, positive thoughts produce good stories.
And yes, I’ve had a drink
Tony1963 said:
heisthegaffer said:
This is another one of those anecdotes that I love hearing about. Very interesting. Cheers
A pleasure!These threads are good for shaking the memories from the back of my mind. When there’s no nastiness, positive thoughts produce good stories.
And yes, I’ve had a drink
Maybe do a thread of interesting things you've seen?
Tony1963 said:
heisthegaffer said:
Thanks again.
Maybe do a thread of interesting things you've seen?
Cheers, but that’s not really me. I’d rather add to the threads of others, although there was my recent thread about Don’t Ask an Ageing Aircraft Maintainer…Maybe do a thread of interesting things you've seen?
Tony1963 said:
The Tornado had fly by wire! As did the F1-11.
However, the huge computing power now available means that designers no longer feel held back by the computers.
Back in the mid-80s at Marham I was sat in a Land Rover waiting for the lights to turn green when a series of Tornados came in to land, wings swept. They were training, just in case. I think they were landing at about 240kts, and the rapid, constant corrections by the CSAS system were clear to see as the tailerons fidgeted away. No pilot could do that.
Modern computers are helping aircraft (such as the Eurofighter) fly that shouldn't physically be able to fly - hence why they can no get by with fixed, swept planforms.However, the huge computing power now available means that designers no longer feel held back by the computers.
Back in the mid-80s at Marham I was sat in a Land Rover waiting for the lights to turn green when a series of Tornados came in to land, wings swept. They were training, just in case. I think they were landing at about 240kts, and the rapid, constant corrections by the CSAS system were clear to see as the tailerons fidgeted away. No pilot could do that.
Another point mentioned to me by an ex-Phantom and Tornado Nav is that swing wings are a fantastic giveaway on the energy state of the aircraft - which is a big disadvantage in a dogfight when each side is trying to second-guess each other
ChemicalChaos said:
Modern computers are helping aircraft (such as the Eurofighter) fly that shouldn't physically be able to fly - hence why they can no get by with fixed, swept planforms.
The computer doesn't allow the aircraft to defy the laws of physics. What it does do is to allow the aircraft to be designed with reduced (or negative) aerodynamic stability (which can be traded for manoevrability, speed range, c of g range etc), and then use an automated flight control system to recover that stability to acceptable levels. The computer also allows many more designs to be assessed and optimised in the design phase, getting closer to the characteristic you want in the first place (see also F117 VS B2!)
ChemicalChaos said:
Modern computers are helping aircraft (such as the Eurofighter) fly that shouldn't physically be able to fly - hence why they can no get by with fixed, swept planforms.
Another point mentioned to me by an ex-Phantom and Tornado Nav is that swing wings are a fantastic giveaway on the energy state of the aircraft - which is a big disadvantage in a dogfight when each side is trying to second-guess each other
Tornados weren't designed to get into dogfights. The ADV was a stand-off missile platform. If its weapons system showed that an incoming aircraft would likely win any sort of fight, it would turn, fully sweep its wings, and out accelerate it. The gun fitted to the ADV was a bit of a joke really!Another point mentioned to me by an ex-Phantom and Tornado Nav is that swing wings are a fantastic giveaway on the energy state of the aircraft - which is a big disadvantage in a dogfight when each side is trying to second-guess each other
Mave said:
The computer doesn't allow the aircraft to defy the laws of physics. What it does do is to allow the aircraft to be designed with reduced (or negative) aerodynamic stability (which can be traded for manoevrability, speed range, c of g range etc), and then use an automated flight control system to recover that stability to acceptable levels.
I don't know, I'd class that as partially defying the laws of physics by constantly stopping a deliberately unstable aircraft falling out of the sky when a "normal" design would glide by itself....Tony1963 said:
Tornados weren't designed to get into dogfights. The ADV was a stand-off missile platform. If its weapons system showed that an incoming aircraft would likely win any sort of fight, it would turn, fully sweep its wings, and out accelerate it. The gun fitted to the ADV was a bit of a joke really!
I know they weren't but I know they also did! My favourite one being when the RAF pitted Phantoms against Tornados to see what they could learn from the outgoing aircraft, and one Phantom famously got a "kill" by engaging a climbing Tonka head-on in a vertical dive....When the ADV first came into service in the F3 version, the pilots had to be told, sternly, that they weren’t to dogfight with each other as, among other things, the tailerons were cracking. Almost new aircraft, cracked flying control surfaces.
The F4 was outmoded by then, especially the U.K. fleet with their silly fuselage to house the RR engines. Limited the intercept speed by quite a lot.
The F4 was outmoded by then, especially the U.K. fleet with their silly fuselage to house the RR engines. Limited the intercept speed by quite a lot.
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