Tail slat question

On Fri, 13 Feb 2004 08:07:37 -0800, "Tarver Engineering"
wrote:


"Ed Rasimus" wrote in message
.. .
On Thu, 12 Feb 2004 17:33:08 -0800, "Tarver Engineering"
wrote:

Weasel, super sonic 100 feet off the ground.


I mean an F-15 in ground effect that fast would be a bad thing.


So, you now think an F-15 is a Weasel?

Not me.

Can you not read your own posts? That is all that I quoted above. We
were discussing high speeds between LES and non-LES Phantoms versus an
F-15. You added the one-liner "Weasel, super sonic (sic) 100 feet off
the ground".

When I suggested that the five aircraft that have performed as "Wild
Weasels" were not particularly fast compared to the standard versions
of the aircraft, you rebutted (non-sequitur) with:

"I mean an F-15 in ground effect that fast would be a bad thing."

Which either means you equate F-15 with "Weasel" or you are trying to
say something you didn't communicate very well. I'm not sure if you
mean "bad thing" as a good thing, either.

I never lied about being a weasel and I have always known the lead is bait.

Of course you never lied about being a Weasel, and I've never said I
was a Weasel either. I've stated repeatedly in this forum that I've
flown combat on the wing of the F-100F, F-105F, F-105G and F-4C
Weasel. I've carried the Shrike, but not the Standard ARM. I've been
honored to have been asked by guys I've flow with to join the Society
of Wild Weasels and proudly hold WW #2488.

The tactics of Hunter/Killer don't employ "bait".


Before your childish editing, we were discussing speed and low and fast the
F-4 has the advantage.

That reminds me of the old childish riddle, "what is the difference
between an orange."

Speed and low and fast, the F-4 has the advantage over WHAT? Certainly
not an F-105. And not an F-104. And not a F-111. And not a Tornado.
There are a lot of aircraft that go faster, lower. Hell, even the
Buccaneer can do better.

Stick to what you know, John. You have credibility there. If you want
to jump in here, answer in whole sentences. Keep track of what you
say. It has to make sense.


Ed Rasimus
Fighter Pilot (USAF-Ret)
"When Thunder Rolled"
Smithsonian Institution Press
ISBN #1-58834-103-8

"Ed Rasimus" wrote in message
...
On Fri, 13 Feb 2004 08:07:37 -0800, "Tarver Engineering"
wrote:


"Ed Rasimus" wrote in message
.. .
On Thu, 12 Feb 2004 17:33:08 -0800, "Tarver Engineering"
wrote:

Weasel, super sonic 100 feet off the ground.


I mean an F-15 in ground effect that fast would be a bad thing.


So, you now think an F-15 is a Weasel?

Not me.

Can you not read your own posts? That is all that I quoted above. We
were discussing high speeds between LES and non-LES Phantoms versus an
F-15. You added the one-liner "Weasel, super sonic (sic) 100 feet off
the ground".

We were discussing under what conditions an F-4 might be faster than an
F-15. If you had left more of the posts in you would have been able to
remember that, Ed.

snip of Ed twisting in the wind

Speed is life, when you are bait.

WaltBJ wrote:

Slots are to raise the lift coefficient (down coefficeint on the
horizontal stab?) at low speeds. Enables raising the nose at lower TO
speeds for more AOA for liftoff at lower speeds. FWIW I never saw an E
without a slotted tail. I first flew LES birds on return to the
cockpit in 76. I was not then and am still not impressed. Can't
remember the exact top speed at 1000 ASl in AB but with 2x275 tanks it
was definitely 50-75 knots slower than our Ds at DaNang - even though
the D was carrying a CL bag, 2 MERs, 2 TERs, 2 x AIM9 and a ECM pod.
Our Ds rang up 745 KIAS at 4000 AGL getting out of Dodge after a
little SAM SEAD, and we were happy to see it. The LES bird could loop
at 300 KIAS from 15,000 in AB - BFD - worthless as a combat maneuver.
You can have all the turn you want - I'll take more speed any day. Ask
the 106 drivers who fought our Dash 19 Zippers about turn vs speed.

OTOH, considering the number of hard wing F-4s that were lost to
departures (probably at least 150. The one source I have handy lists
USMC/USN admitted losses to this cause up to August 1971 at 79. USAF
losses were probably higher) and the poor state of high alpha training in
the average USAF pilot from 1967 or so, the slats made a lot of sense as
far as keeping the average pilot from departing due to adverse yaw while
maneuvering with a heavy load. Steve Ritchie's wingman John Markle and
his WSO lost their a/c to this cause while in a fight over NVN on May
20th, 1972 (CSAR got them both out)

Owing to the lack of edge of the envelope training (to keep the safety
stats looking good), pilots often encountered the F-4's departure
characteristics for the first time in combat, and didn't know how to
recognize it until too late. Initially the navy figured that they could
fix the problem with improved crew training, but eventually they went for
the same hardware solution that the USAF had already adopted even though
it was less of a problem for their F-4s, given the different mission
distribution compared to the air force (less A/G, more FAD/AtA).

Ultimately, the departure and flight characteristics of the F-4 (and the
F-8, F-100, F-101 and F-104, among others) led the military to put a great
deal of energy and money into flight control and aerodynamic design to
idiot-proof the next generation of fighter a/c (i.e. F-15/16/18 and to a
lesser extent, F-14), to allow the average pilot carefree handling to near
or on the edge of the envelope, while keeping them out of trouble. The
F-5 was an early nudge in that direction as well. There's no doubt that
a/c like the F-16 with hard FC limits that can't be overridden will
penalize the good sticks on some occasions (I'm reminded of the Top Gun
instructor who used to deliberately depart his F-4, to allow him to make
maneuvers that no one else could match), but the average pilot can use so
much more of the envelope confidently that there's an overall improvement
in capability, and a lower attrition rate. They've also improved the
training, obviously, but training time will always be limited and
expensive.

Guy

Why then German F-4Fs does not have them?

--

Nele

NULLA ROSA SINE SPINA
Alan Dicey wrote in message ...
Ed Rasimus wrote:
On Fri, 13 Feb 2004 12:25:04 +0100, "Nele VII"
wrote:


What the heck the inverted slat is doing on F-4J then, Ed? It has no gun!


BTSOM! Ask a sailor.

Might be to counter a heavier radar, or maybe a balance to the drooped
ailerons or for better control immediately after cat shot. Dunno.


I dimly recall reading that the tailplane inverted slot on the F-4 was
to increase control effectiveness at low speed, during carrier
approaches. Googling, I found the following helpful quotes:

http://home.att.net/~jbaugher1/f4_11.html
The second production F-4E (66-0285) flew for the first time on
September 11, 1967. It differed from 66-0285 by having a slotted
stabilator. This slotted stabilator was added in order to give greater
tailplane effectiveness, helping to counteract the increased weight in
the nose.

http://www.vogue-web.ch/f4/f4_21.html
Even though the Navy wanted better takeoff and landing performance for
the Phantom, it nevertheless felt that speed, climb, and range
requirements ruled out the use of the high-drag slatted wing that was
used by the Air Force on the F-4E. In the pursuit of better takeoff and
landing performance, McDonnell decided instead to add a slot to the
stabilator leading edge, effectively turning it into a miniature
inverted slatted wing. This slotted stabilator provided a tremendous
downward force at low speeds, which allowed a large leading edge down
deflection without stalling. The effectiveness of the slotted stabilator
was markedly improved by locking the inboard leading flap in the up
position.

http://home.att.net/~jbaugher1/f4_25.html
The F-4N was fitted with an F-4J-style slotted stabilator which helped
solve "Mach tuck" problems when decelerating from supersonic speeds and
which reduced approach speeds during landings. All F-4Ns had their
inboard leading-edge flaps locked shut.

So, it seems that the main purpose of the inverted slot is, as I
thought, to increase the control authority of the all-moving tail at low
speeds, allowing landing speeds to be reduced. An additional benfit
seems to have been in the transonic region, again in terms of control
authority.

Looking at it from first principles, this makes sense: the slot is
inverted, so it will be affect the downforce-capability of the tail: as
the tail is all-moving this translates into extended control authority.
The airflow is persuaded to stay attached to the tail surface at
lower speeds and/or higher AoA than a non-slotted tail.

Mind you, I am not a pilot, so cannot speak with any authority on the
subject: just offer the thoughts to add some light to the discussion.
Hope this helps...

Nele VII wrote:

Why then German F-4Fs does not have them?

All I can do is look for some explanation in my reference books and on
the web. Here's what Joe Baugher says:

http://home.att.net/~jbaugher1/f4_17.html
175 examples of the F-4F were ordered by the West German government. The
F-4F emerged as a lighter and simpler F-4E which was significantly
cheaper and incorporated major components that were manufactured in
Germany. The number 7 fuselage fuel tank was removed and all Sparrow
equipment was eliminated. The AN/APQ-120 radar was simplified, with no
beacon search or constant wave illuminator being provided for Sparrow or
Falcon missile launches. Although no inflight refuelling receptacle was
initially fitted, the internal plumbing needed for midair refuelling was
installed at the factory. An unslotted tailplane was used as an economy
and weight-saving measure [...] The design that finally emerged was 3300
pounds lighter than the stock F-4E.

And about other post-E Phantoms: -

http://home.att.net/~jbaugher1/f4_22.html
(RN F-4K)
A double-extensible nose undercarriage leg was used to enable high angle
of attack carrier launches to be made. The gear could be extended in
length by as much as 40 inches. This arrangement was first tested on a
Navy F-4B during trials aboard the USS Forrestal. In the interest of
achieving slower carrier landing approach speeds, larger wing leading
edge flaps were fitted and boundary layer control was applied. The
amount of anhedral on the stabilator was reduced, and slats were
provided on the stabilator leading edge.

http://home.att.net/~jbaugher1/f4_23.html
(RAF F-4M)
The RAF version lacked the slotted stabilators, the double-extensible
nose leg, and the aileron droop of the naval variant. The F-4M was
fitted with anti-skid brakes for safer operations on wet or short
runways. Like the F-4K, the F-4M was not equipped with an internal
cannon.

Does this help?

"Gord Beaman" wrote in message
...



This is not true.

Maybe for slats it is ... but not for slots.

The tailplane is designed merely to control the wing which does
the whole of the lifting job. The tail actually 'pushes down' in
level flight. This produces 'fore and aft' stability just as wing
dihedral produces horizontal stability.

Like the man said, Gord, the Cessna 177 Cardinal had slots on the leading edge
of the horizontal stabiliser.

They were *inverted*, to keep that tail pushing down at low speeds.

GRIN