Swing Wings: Yea or Neah?

Why have most newer fighter designs not used swing wings?
It seems in the US, the F14 and F111 were the last to go with
swing wings. It seems the major reasons for using them is having the
best of both worlds in wing loading at both low and high speeds.

Why have the newer designs avoided them? Maintenance?
Weight? Cost?

Also, most newer fighter designs use twin tails canted out from
perpendicular. Is there a reason this is better than straight
dual perpendicular tails?


Bob




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BOB URZ wrote in message ...
Why have most newer fighter designs not used swing wings?
It seems in the US, the F14 and F111 were the last to go with
swing wings. It seems the major reasons for using them is having the
best of both worlds in wing loading at both low and high speeds.

Why have the newer designs avoided them? Maintenance?
Weight? Cost?

From what I can see mostly maintainance. Advances in engines: they
are both more fuel efficient, lighter and more powerfull for the same
size means that performance such as take of run, range and top speed
can be achieved without resorting to the complexity of swing wings and
the space and weight liberated can best be used to carry more fuel. I
note also aerodynamics such as strakes and leading edge extensions
have also helped as have reductions in airframe weight.

Still the low wind gust response of an Panavia Tornado with wings back
at low level penetration is much better than an F15E but low level
penetration is nuts accoding to the USAF.




Also, most newer fighter designs use twin tails canted out from
perpendicular. Is there a reason this is better than straight
dual perpendicular tails?

Probably to get them in to clean airflow at high angle of attacks.



Bob




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"The Enlightenment" wrote in message
m...

snip

Still the low wind gust response of an Panavia Tornado with wings back
at low level penetration is much better than an F15E but low level
penetration is nuts accoding to the USAF.


So that's why they leave it to the British?! )

Jim

"BOB URZ" wrote in message
...
Why have most newer fighter designs not used swing wings?
It seems in the US, the F14 and F111 were the last to go with
swing wings. It seems the major reasons for using them is having the
best of both worlds in wing loading at both low and high speeds.


....don't forget the B-1

Why have the newer designs avoided them? Maintenance?
Weight? Cost?


It's probably a combination of all three, though someone also pointed out
that engine efficiency has a lot to do with it as well. Newer engines are
indeed more versatile in their application of power, and I would probably
add that aerodynamics have come a long way as well.

That is not to say that there is no benefit at all in having a swing-wing,
but the advantage is minimized by these advances to a point that it no
longer becomes cost effective to incorporate variable geometry into a modern
design.

However, if I remember correctly, I did see some designs for a new SST
concept that utilized varible geometry wings. Not much came of it though, at
least I dont think.

Also, most newer fighter designs use twin tails canted out from
perpendicular. Is there a reason this is better than straight
dual perpendicular tails?

That has more to do with steath than anything else. 90-degree angles are a
major no-no in stealth design. So simply canting the tail surfaces inward or
outward can greatly reduce a radar signature. I believe that this was first
discovered on the SR-71; the engineers lowered its signature by something
like 30% or so just by giving it inward canted stabilizers.




Bob




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The swing wing mechanism adds ALOT of weight, the smaller the airframe the
larger the percentage weight gain. On both F14s and F111s the tradeoff to
optimum performance was considered acceptable in order to acheive both good
high speed performance (usually requiring a small wing) and good low speed
landing performance (large wing). B-1s made the same design choice for the
same reason. Fighters generally are optimised for maximum performance and
minimum weight and therefore can not justify carrying the extra weight of a
swing wing just to gain a lower landing approach speed.


"BOB URZ" wrote in message
...
Why have most newer fighter designs not used swing wings?
It seems in the US, the F14 and F111 were the last to go with
swing wings. It seems the major reasons for using them is having the
best of both worlds in wing loading at both low and high speeds.

Why have the newer designs avoided them? Maintenance?
Weight? Cost?

Also, most newer fighter designs use twin tails canted out from
perpendicular. Is there a reason this is better than straight
dual perpendicular tails?


Bob




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Jim Doyle a écrit :

"The Enlightenment" wrote in message
m...

snip

Still the low wind gust response of an Panavia Tornado with wings back
at low level penetration is much better than an F15E but low level
penetration is nuts accoding to the USAF.



So that's why they leave it to the British?! )

Jim


B'cause they, the US, have no more balls...

In article ,
Nemo l'ancien wrote:

Jim Doyle a écrit :

"The Enlightenment" wrote in message
m...

snip

Still the low wind gust response of an Panavia Tornado with wings back
at low level penetration is much better than an F15E but low level
penetration is nuts accoding to the USAF.



So that's why they leave it to the British?! )

Jim


B'cause they, the US, have no more balls...


No, it is because, with stealth and PGMs there is really no longer a
need for low-level penetration. Brains over balls every time!

"Thomas J. Paladino Jr." wrote in message
. ..

However, if I remember correctly, I did see some designs for a new
SST
concept that utilized varible geometry wings. Not much came of it
though, at
least I dont think.

That's the now-ancient Boeing SST proposal. Boeing's engineers had
to tell management the fuselage could carry the swing-wing mechanism
or passengers, but not both. ;-(

"Thomas J. Paladino Jr." wrote in message ...
"BOB URZ" wrote in message
...

Also, most newer fighter designs use twin tails canted out from
perpendicular. Is there a reason this is better than straight
dual perpendicular tails?

That has more to do with steath than anything else. 90-degree angles are a
major no-no in stealth design. So simply canting the tail surfaces inward or
outward can greatly reduce a radar signature. I believe that this was first
discovered on the SR-71; the engineers lowered its signature by something
like 30% or so just by giving it inward canted stabilizers.

I seem to recall that high-alpha directional stability also is
improved. That had a lot to do with the tailplane placement on the
Hornet...a little further forward and canted outward, so when it's
doing its slow, nose-high thing, the tailplanes still are effective.
I would imagine that that's an issue with the Raptor, too.

"breyfogle"

The swing wing mechanism adds ALOT of weight, the smaller the airframe the
larger the percentage weight gain. On both F14s and F111s the tradeoff to
optimum performance was considered acceptable in order to acheive both good
high speed performance (usually requiring a small wing) and good low speed
landing performance (large wing).

I'd think that low-level high-speed performance was also an
important design consideration. Or, at least, it was found
useful for the low-level penetration missions that became the
primary tasks of F-111 and B-1B during the cold war.

MiG-23 is an interesting case. It's a relatively light
fighter with swing wings. Any comments on why MiG chose
such a design? Hardly just for STOL, although the Soviets
valued rough&short strip ability much more than the US
(MiG-29 perhaps as a prime exampole). Btw, 23 is very
fast on the deck, fastest of them all, I think.

I'd suspect that the design considerations behind MiG-23/27
could have been rather similar to those of the somewhat
heavier interceptor/strike Tornado.