A-5 Vigilante Spin

[megan]

The book says you are highly unlikely to be able to recover from a fully developed spin, but suggests the best control positions for recovery would be,



The question is what would be the aerodynamics behind the full back stick recommendation?

[Easy Street]

That's the same stick position as the spin recovery in a Tornado, and the aerodynamic logic in that case was to improve airflow over the fin when descending at very high AoA to try to stop the rotational motion. The stick was centralised once AoA came back on scale. A low probability of success was expected. I would hazard a guess that similar logic applies here.

[Mogwi]

B/A ratio. Harrier was the same.

Mog

[Asturias56]

Beautiful aircraft - the RA-5C especially...........

[sandiego89]

Originally Posted by Asturias56

Beautiful aircraft - the RA-5C especially...........

I have a soft spot for the original A3J (A-5) look, both versions do look great. I have had the pleasure to see the sole surviving "flat top" A-5 at Pax River, still looks great and dramatically posed sitting on its pole in a quiet corner of the base. Would like to see here come inside, or a place where more people could see her.

[megan]

Thanks Easy, conformation for what I thought looking at the plan of the aircraft. Only ever saw the aircraft once in my life, in the hangar on board the "Enterprise" at NAS Alameda December 1967 as she was loading for Vietnam. As Asturias says, one beautiful aircraft, if I recall one had to have had two prior tours to get a posting.

[West Coast]

What I always found fascinating about the aircraft is how it dropped it bombs, ejecting them out the back.

[ORAC]

Wiki:

The single nuclear weapon, commonly the Mk 28 bomb, was attached to two disposable fuel tanks in the cylindrical bay in an assembly known as the "stores train".

A set of extendable fins was attached to the aft end of the most rearward fuel tank. These fuel tanks were to be emptied during the flight to the target and then jettisoned with the bomb by an explosive drogue gun.

The stores train was propelled rearward at about 50 feet (15 m) per second (30 knots) relative to the aircraft. It then followed a ballistic path.[16]

In practice, the system was not reliable and no live weapons were ever carried in the linear bomb bay. In the RA-5C configuration, the bay was used solely to accommodate fuel.

On three occasions, the shock of the catapult launch caused the fuel cans to eject onto the deck; this phenomenon reportedly resulted in one aircraft loss.[17]

[57mm]

IIRC, the Viggie had an all-moving fin......

[SpazSinbad]

'megan' you may find useful info in NATOPS, here is some info:

A-5A AIRCRAFT NATOPS Flight Manual NAVY MODEL 1965

https://docdro.id/GxkZXeu (PDF 61Mb) or http://aviationarchives.********.com/search?q=vigilante

HORIZONTAL STABILIZERS
The horizontal stabilizers, constructed in two one-piece slabs, are attached to spindle fittings on the fuselage below the vertical stabilizer. These control surfaces have a travel range of 15 degrees leading edge up and 18 degrees leading edge down. Changes in pitch trim are made by small movements of the entire surface. Changes in lateral (roll) trim are accomplished by differential deflection of the horizontal stabilizers.

VERTICAL STABILIZER
The vertical stabilizer is a one-piece, all-movable surface. Total surface travel is 16 degrees; 8 degrees either side of center. Vertical stabilizer travel is regulated by a ratio-changing mechanism controlled by the position of the wing flaps. Stabilizer travel varies linearly from 2 degrees left or right ( with flaps up) to 8 degrees left or right (with flaps down 25 degrees or more). A position light, buddy tanker signal lights, and a fuel overboard vent are installed in a fairing on the trailing edge of this surface.

WARNING
Avoid abrupt, large magnitude, longitudinal control motions in maneuvering flight. If the stall warnings of lateral control deterioration, moderate to heavy airframe buffet and rudder pedal shaker actuation are ignored, or if extreme control motions cause the aircraft to depart abruptly from controlled flight, the aircraft may enter a developed spin from which recovery is highly unlikely.

WARNING
INTENTIONAL SPINS ARE PROHIBITED. During the spin test program, a spin mode was encountered from which no satisfactory recovery, using the production design control system, was possible.

WARNING
In the event the post-stall gyration progresses to a fully developed spin, it is highly unlikely that recovery can be effected.

[megan]

What I always found fascinating about the aircraft is how it dropped it bombs, ejecting them out the back

Except it didn't work in practice, the driver of one (squadron Ops officer) wrote, "Although a viable system in theory, in actual practice difficulties were encountered in clearing the linear bomb bay during operational use". Whether it be right or wrong, truth or rumour, our USN instructors during basic said the problem was, when ejected, the the load sat in the aircrafts wake and followed it in trail formation, identical to what you see if you toss something into a boats wake.

Thanks Spaz, was after the A-5A manual, my initial post came from the RA-5C Natops.

[SpazSinbad]

This is a 1965 RA-5C NATOPS: RA-5C NATOPS 1965
https://www.docdroid.com/v2g1HDn/nor...al-earlier-pdf (60Mb)

'megan' you may remember this exclamation? Started by Ralph (SKULL) for my nickname change.

Geez Luigi Joey S1E22-8sec

You Tube

[B2N2]

Originally Posted by SpazSinbad

This is a 1965 RA-5C NATOPS: RA-5C NATOPS 1965
https://www.docdroid.com/v2g1HDn/nor...al-earlier-pdf (60Mb)

Beautiful, saved for the boring bits of flight.

[megan]

Sigh, you bring back memories Spaz, GN lived next door and was away this particular weekend, went out the back door to find "Skull" washing his car at GN's place, on completion I pulled a couple of beers from the fridge and chatted, last I saw of him as a few days later was the event.

[SpazSinbad]

Yeah I was supposed to fly that TA4G that day but earlier had reminded our SP that I had a dental appointment at the same time - so Ralphie took my place. I wonder if it could have been me? Having read the crash report many times no one knows how events unfolded - or how it happened. That TA4G was a bit 'wobbly' (a characteristic of the second hand lot of A4Gs/TA4Gs). SKULL was the best indeed - a sad loss to the RAN FAA.

[OK465]

The question is what would be the aerodynamics behind the full back stick recommendation?

In the jet aircraft that I've 'spun' (spinated??), both the T-37 and T-33, and the others that I haven't, the initial stick full aft advice was to assure you weren't in an inverted spin before other recovery inputs were applied. In an inverted spin in the aircraft I'm familiar with, stick full aft will result in transition to an upright spin. From there you're dealing with a known quantity, inverted spins can be very disorienting, uncomfortable and difficult to assess. Intentional inverted spins in the T-6 are prohibited for this reason, not because they're unrecoverable.

T-37 recovery was essentially the same as the A-5 procedure and was, of course, taught regularly in USAF training because the habit patterns carried over to fighter aircraft of the time. Nowadays you just let the FBW take care of you.

BTW, probability of recovery in the A-5 sounds about the same as that of an F-100F.

[SpazSinbad]

This link to OneDrive is for the 139Mb A4G NATOPS PDF which is text searchable and has bookmarks. Anyone can use this link to download directly. Let me know if there is a problem. The PDF is also on GOOGLEdrive if that is easier.

OneDrive: _A4G_NATOPS_Text_Searchable+BookMarks.PDF (139Mb)

https://1drv.ms/b/s!AuYHBzTWY83LikE-...4XQ5k?e=NWQNM8

[OK465]

It appears the A-4 had enough aileron adverse/proverse yaw capability to assist the rudder in slowing the rotation. They only offer the adverse yaw input in the A-5, aileron with the spin, apparently because that initial stick aft input assures an upright (erect ) spin. Positive versus any chance of negative G.

The poor A-4 guy has to decide whether he's attempting recovery from an upright or inverted mode before inputting ailerons. Air Force just begged the question and turned everything into a upright spin prior to subsequent control inputs. KISS.

T-37 straight wing didn't have a lot of aileron adverse/proverse yaw capability to counter rotation, so rudder was it, but I don't how many times I've seen students (and new IPs occasionally) initially misinterpret the spin direction in the inverted maneuver prior to transition to erect and even occasionally in the upright spin and jam in the wrong rudder. Turn needle is your friend.

I wonder how long the Nav/Bomb guy in the RCP with the little porthole window would have stayed with an A-5 in a spin while the pilot attempted that recovery procedure?

[BEagle]

Some idea of the zoom climb capabilities of the A-5A was provided on December 13, 1960 when an early production aircraft attained 91446 ft with a 2200 lb payload......

That must have been quite a ride!!!

[megan]

Strictly speaking the altitude record was made in 1960 with a A3J-1 by Pilot Leroy (Roy) Heath and B/N Larry Monroe, the A3J's were later designated A-5A in 1962 under a new Tri Service designation system, and later still the A-5A were converted to RA-5C. Accelerated to 2.1 Mach before pulling up into a ballistic flight path, as it went over the top aircraft inverted (gyroscopic effect of still rotating flamed out engines?), pilot did not intervene and allowed aircraft to establish itself in the descent.