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Curtiss Proposal II

1948 COLD WAR X-PLANE

History of Curtiss Proposal II

After World War II (1939-1945) and the advent of the jet age, many US airlines competed for a limited number of research contracts. Like the United States Air Force (USAF), the United States Navy (USN) conducts several aircraft research programs to uncover the mysteries of flight (and its many dangers) for near-term applications.

The U.S. Navy's first supersonic fighter, Grumman's F11F Tiger, grew out of a series of evolving aircraft programs, such as the one to produce the Douglas D-558-II "Skyrocket" rocket-powered supersonic research aircraft.

One attempt by Curtis to compete with the D-558-II was "Proposal II" which was eventually abandoned.

The primary research objective of Proposition II is to collect data on subsonic and supersonic flight speeds and their relationship to surfaces, structures, and engine control.

Proposition II is the second part of two different research aircraft proposals put forward by Curtis - the first is simply referred to as "Proposition I". Advice I definitely look like a research aircraft as it is built along an extremely slender needle-nose fuselage, thin main wing and "T-shaped" tail.

Power will come from a rocket engine built by Curtis. Proposal II, the more radical of the two, proposed a more compact fuselage designed in the shape of a three-blade "arrowhead" with a single-seat cockpit at the bottom of the vertical tail. The wings are concentrated on either side of a slender fuselage that houses the necessary fuel storage, engines, cockpit, avionics suite and data acquisition equipment. At the front is a circular air intake in a twin-engine layout.

At the stern, there are two exhaust outlets under the rear wing and on either side. The arrow method negates the use of a horizontal stabilizer and is largely reminiscent of a German design during World War II - the 1944 Lippisch P. 13A interceptor.

The program introduced some small gliders for testing before the end of the war. The completed interceptor product would live on with a unique coal-fired engine (the P.13A survived in postwar testing as NACA's "DM-1" experimental glider - the predecessor to today's NASA).

Proposition II is powered by 2 Wright ramjets, each providing 6,000 pounds of thrust. The Curtiss booster rocket will be suspended below the fuselage to add 4,000 pounds of thrust -- mostly for initial acceleration.

Once the booster rocket runs out of fuel, the unit ejects from the vehicle and falls on its own under the power of a parachute for salvage and reuse on future launches.

Both Proposal I and Proposal II drafts detail that the Boeing B-29 Superfortress will serve as the launch vessel - meaning the test aircraft will fly using the power of a modified four-engine bomber (the test vehicle sits on the fuselage) bomber) and take off at an altitude of about 30,000 feet. The test plane will then run on its own power after takeoff.

A tricycle landing gear was installed to allow the plane to slide back after the test was completed. This type of delivery was not entirely uncommon during this periodearly rocket-powered aircraft such as the Bell X-1 and North American X-15 were air-launched vehicles, and several USAF "parasite" combat programs envisioned similar "Mothership" "provides effective self-defense capability for high-altitude bombers.

Dimensions for Option II include a wingspan of 21 feet 6 inches, an overall length of 30 feet, and a combined weight of 10,350 pounds with booster rockets installed.

Based on their estimates, Curtis engineers claimed a top speed of 747 mph at 2,000 feet, but it only lasted 60 seconds. It can still hit 975 mph at 10,000 feet, despite only holding it for 10 seconds. Top speed is estimated to reach 1,900 miles per hour, with an estimated altitude of 50,000 feet.

The optimistic Proposal II ended up being criticized during its naval review. It is believed that despite the aerodynamically efficient arrow design, the aircraft struggled to achieve its intended supersonic speed??mainly due to the limitations of the ramjet engine at the time, which itself could not generate speed until the aircraft itself reached speed The required power is at least 1,205 miles per hour. Even the prospect of having the test aircraft dive to achieve the desired outcome was not enough to convince the Navy of the merits of Proposition II. Other U.S. Navy development aircraft already in service at the time also met some of the program objectives of Proposition II.

Consequently, Curtis Proposition II was removed from any real further consideration by the US Navy.

The Douglas D-558-II had a successful test career in the US Navy and three were built. It reached a speed of Mach 2 on November 20, 1953.