Blackbird
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F-16 Torsional Agility And Wing-Loading

Tue Oct 07, 2008 3:56 am

To the best of my knowledge, the F-16 was the first fighter to feature torsional agility (Though I could be wrong) which allowed a relatively light wing-loading to sustain high-G's more effectively at higher airspeeds than would typically be allowed without the torsional-agility.


I have a couple of questions pertaining to this...

1.) Was it possible to design an airplane with torsional-agility prior to the F-16 (Did the technology and construction technology exist prior to the F-16's program started to produce the desired result)?

2.) How much of an improvement does torsional-agility provide in terms of allowing a lightly-loaded fighter at high airspeed to avoid excessive speed-losses in sustained-G performance? Like 10%, 20%, etc?

3.) Does torsional-agility require an unstable airframe?


Blackbird
 
2H4
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RE: F-16 Torsional Agility And Wing-Loading

Tue Oct 07, 2008 4:05 am

In order to answer those questions, I think you first need to precisely define the term "torsional agility". How would you define it?

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Blackbird
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RE: F-16 Torsional Agility And Wing-Loading

Tue Oct 07, 2008 4:28 am

I'm not 100% sure, but from what I was told by another member, it had to do with the aero-elastic properties of the plane. Most wings naturally do twist leading edge down in response to loading (forward swept wings are an exception). Torsional-Agility seems to involve tailoring the aero-elastic characteristics so this occurs in a more pronounced fashion when high-G's are pulled at high airspeeds in such a way as to reduce lift under those conditions -- which is very useful for a plane with light wing-loading (which maneuvers superbly at low to intermediate speeds due to it's high lift to drag-ratio; at high-speeds the amount of lift produced is much higher, and with it, so does drag, which results in less ability to sustain high-G's) as it allows a lightly-loaded wing to sustain high-G's even at high-airspeeds where a conventional wing (same loading, non torsional-agility) couldn't.


Blackbird
 
wingscrubber
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RE: F-16 Torsional Agility And Wing-Loading

Wed Oct 08, 2008 3:04 am

My only relevant knowledge of the F-16 is that it's horizontal stabilizer/elevator, or stabivator if you will, can input roll control aswell as pitch. In addition I believe the leading edge slats can input pitch control by deploying under large pitching-up inputs such as in a tight turn to add lift to counter the increased load factor. (In laymans, when you pull up hard, the slats deploy)
Or at least that's what I've seen simulated...

Oh, and of course, it's a fly-by-wire aircraft, so 'torsional agility' could well just be a peice of software! 'Aero-elastic properties' sound interesting, never heard of that term before.
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Blackbird
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RE: F-16 Torsional Agility And Wing-Loading

Wed Oct 08, 2008 9:42 am

Wingscrubber,

Doesn't the A-4's slats also deploy in response to G-inputs?


Blackbird
 
Starglider
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RE: F-16 Torsional Agility And Wing-Loading

Thu Oct 09, 2008 10:50 am



Quoting Wingscrubber (Reply 3):
I believe the leading edge slats can input pitch control by deploying under large pitching-up inputs such as in a tight turn to add lift to counter the increased load factor. (In laymans, when you pull up hard, the slats deploy)

Just to be clear, the F-16 has leading edge flaps, not slats. They automatically deploy when airborne with gear down and in flight with gear up depending on airspeed, angle of attack or while manoeuvring.

Starglider
 
Blackbird
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RE: F-16 Torsional Agility And Wing-Loading

Fri Oct 10, 2008 3:47 am

Starglider,

You learn something new everyday -- I thought the F-16 had slats, and the F-18 had droops (leading-edge flaps)


Blackbird

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