FMA IAe 33 Pulqui II

Fuel capacity was initially 1,250 l (275 Imp. gal.) internally and 800 l (176 Imp. gal.) in the wings.

Armament was planned to include four 20 mm cannon, a pair mounted in a staggered, near-ventral position along each side of the fuselage slightly set back from the jet intake.

Testing and evaluation

To prove the soundness of the IAe 33 design, two gliders built under contract by another expatriate, [Vous devez être inscrit et connecté pour voir ce lien], were constructed and used for aerodynamics testing in 1948–1949, including flights by Tank himself.

These tests revealed significant problems with lateral stability, resulting in modifications to the tail to address this problem before construction began on two prototype airframes.

Due to the lack of modern machinery, the all-metal fabrication relied heavily on hand crafting and turning out the prototypes was a labor-intensive procedure.

President Perón envisioned that a benefit of setting up an aviation factory in Argentina would be to introduce production standards comparable to world-class manufacturing facilities.

However, Tank realized that production tools and jigs were not feasible at this stage and relied instead on essentially hand-built examples.

The first airframe (No. 01) reserved for static testing, was subsequently destroyed during the tests.

The first of the "flying" IAe 33 prototypes, (No. 02) built in 1950, completed its maiden flight on 27 June of that
year, with Captain Edmundo Weiss at the controls.

On the second flight, ex-Focke-Wulf test pilot Otto Behrens encountered severe lateral stability problems at speeds over 700 km/h (435 mph) and returned to the airfield as a precaution.

Landing at very high speed, the aircraft bounced with sufficient force to cause the right main undercarriage strut to fail.

During repairs to the aircraft, in order to rectify the "tricky" landing characteristics, the front undercarriage strut was increased in length, which served to alter the angle of incidence of the aircraft, while the shock absorbers were adjusted to have a greater "throw".

Although never considered docile, the modifications improved the takeoff, landing and low-speed characteristics of the IAe 33.

More serious aerodynamic problems persisted, stemming from [Vous devez être inscrit et connecté pour voir ce lien]—when the wingtip stalled before the wingroot
resulting in an unpredictable "rolling moment"— that led to a change in the wing leading edge near the wingroot, while the rudder was modified in an attempt to resolve the interminable lateral instability issues.

In addition, the canopy was reinforced with two external frames and a small fairing was installed above the engine exhaust.

Tank, himself a capable development test pilot, took over the test program to investigate the aircraft's stalling
characteristics, although the requisite airframe changes took several months to complete, with the Pulqui II N. 02(m) for modified, not able to undertake its third proving flight until 23 October.

During the ensuing high-altitude test, on two successive occasions, the IAe 33 stalled inadvertently, although Tank had sufficient height at 9,000 m for recovery.

Adding ballast to the nose of the aircraft cured the problem.

On 8 February 1951, Tank publicly demonstrated the IAe 33 before Perón at the [Vous devez être inscrit et connecté pour voir ce lien] in
Buenos Aires.

The audience also included government officials, legislators and the foreign diplomatic corps in the military attaches of the embassies, along with a large crowd of spectators.

Both the IAe 27 Pulqui I and IAe 33 Pulqui II flew during the demonstration.

Pulqui II planeur

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With the successful completion of the proving test flights, the [Vous devez être inscrit et connecté pour voir ce lien] requested a pre-production order of
12 IAe 33 aircraft.

In 1951, the air force established a team of service pilots to test fly the new aircraft in a series of acceptance flights.

The first flight by Commander Soto on 31 May 1951 revealed severe vibrations around 1,000 kilometres per hour (621 mph).

Tank declared the sole prototype unserviceable pending an investigation into the problem, although this stricture appears to have been overlooked and the prototype continued to fly.

On the eve of its 28th flight, Captain Vedania Mannuwal, assigned to the test program, was advised not to stress the aircraft, as the source of the vibrations experienced during the previous flight in the morning had not been discovered.

Determined to "better" his team leader's recent performance, however, he ignored the precautions and began practicing
aerobatic maneuvers near Córdoba during his afternoon flight.

Consequently, in a [Vous devez être inscrit et connecté pour voir ce lien] turn, a [Vous devez être inscrit et connecté pour voir ce lien] occurred with the wing separating from the fuselage.

After struggling with the [Vous devez être inscrit et connecté pour voir ce lien] Mk I [Vous devez être inscrit et connecté pour voir ce lien], Mannuwal ejected at low altitude while the aircraft was inverted.

His parachute did not fully deploy, however, and he was killed.

The defect in the Pulqui II was traced to faulty workmanship related to welding the joint pin that fastened the wing to the fuselage.

Welding had been a dichotomy in the manufacturing process necessitated by the paucity of modern forging and pressing equipment in Argentina.

Construction of a third prototype (No. 03) began immediately after this loss.

The design team initiated a number of changes to rectify design flaws found in the first "flying" prototype, including a
incorporating larger rudder to improve lateral stability, increasing the size of the exhaust fairing and adding a unique [Vous devez être inscrit et connecté pour voir ce lien] that rotated out from the sides of the fuselage near the tail, along with further reinforcement of the canopy.

More fuel was also carried internally to extend the range from 2,030 to 3,090 kilometres (1,260 to 1,920 mi).