Argentine Aircrafts: IA.37, Mach 2 that Would Never be Achieved

The IA.48, absolute ambition

If the IA.37 was the promise, the IA.48 was absolute ambition. It was the final evolution of Reimar Horten’s supersonic interceptor concept at the Fábrica Militar de Aviones (FMA).

There is often confusion between the two, but the IA.48 was a far more complex and powerful machine. Here’s what we know about this “fighter of the future” that never came to be:

1. The leap to Mach 2
   While the IA.37 was designed to brush the speed of sound (Mach 1.2), the IA.48 aimed to reach Mach 2.2. To achieve this, Horten moved away from a simple delta-wing design and proposed a much more refined configuration:

• Wing planform: an ogival delta wing with a very sharp leading edge, optimised for sustained high supersonic speeds.

1. Engines in pods: Unlike the IA.37 (which had the engine in the fuselage), the IA.48 was to have two Rolls-Royce Avon turbojets mounted in pods beneath the wings (or integrated, depending on the design phase). This freed up space in the fuselage for fuel and radar equipment.

2. Innovation for the Navy: “blown flaps”.
   One of the most interesting aspects of the IA.48 was the Argentine Navy’s interest. For a fighter that fast to land on an aircraft carrier (such as ARA Independencia), it needed a low approach speed. Horten designed a blown-flap system that used engine bleed air to generate extra lift at low speeds. This was cutting-edge technology, only just beginning to be adopted by the major world powers.

3. The wind tunnel and real progress.
   The IA.48 was not just a paper concept. Extensive tests were carried out:

• 1:25 scale stainless-steel models were built.

• They were tested in supersonic wind tunnels, reaching simulated speeds of up to 2,000 km/h.

• The results confirmed the wing shape was excellent for transonic and hypersonic flight.

4. Why was it cancelled?
   In 1960, the project was abruptly cancelled, along with the IA.37. The reasons were a mix of factors that repeatedly affected the national industry:

• Economics: Minister Álvaro Alsogaray implemented an extremely strict austerity plan that cut funding for the FMA’s long-term projects.

• External pressure: There was a strong tendency to abandon domestic development and instead buy surplus US equipment (such as F-86 Sabres), which was cheaper in the short term but undermined local engineering.

A detail to avoid confusion.
It’s common online to see mention of TC-48, but that was a Douglas DC-4 (a real transport aircraft that disappeared in 1965 in a tragic accident). IA.48 refers strictly to Horten’s supersonic fighter project.

Projected technical summary

• Maximum speed: Mach 2.2 (approx. 2,300 km/h)

• Crew: 1 or 2 (depending on the all-weather interceptor version)

• Armament: Air-to-air missiles and 30 mm cannon(s)