Saturday, August 12, 2006

Tarmac Saturday

Steeljaw Scribe, a blog I've started reading recently, has a feature called "Flightdeck Friday" in which he takes a lesser-known, rare, or just plain weird USN carrier aircraft. Living up the adage that imitation is the highest form of flattery, I've decided to start my own feature over here called Tarmac Saturday featuring the cool, rare, or strange among USAF aircraft. Starting it off, we'll take a look at what happens when you shoehorn the engine that powered the B-29, the Wright Duplex Cyclone 18-cylinder engine, into a single-engine high performance interceptor.

The Curtiss XP-62 developed out of a Jan. 1941 USAAC requirement that called for a heavily armed single seat interceptor that was capable of a max speed of 468 mph at 27,000 ft. and a minimum armament of 8 20mm or 12 .50 machine guns. By comparison, the heaviest armed aircraft of the war were either the P-47, with it's 8 .50 machine guns or the P-61B with it's 4 20mm cannon and 4 .50 machine guns. The XP-62 was definitely designed to pack a serious punch. The airframe was pretty standard; cantilever low-wing monoplane. Things got interesting around the front end. As I mentioned before, the powerplant for this aircraft was the same one used eventually to power the B-29: the Wright Duplex Cyclone R-3350-17, an 18 cylinder 2300 hp radial behemoth. The Duplex Cyclone powered two three bladed contra-rotating propellers. 2300 hp was pretty heavy by WWII standards, but for an aircraft designed in 1942 this was astronomical. In addition, the engine was to be fitted with a turbocharger and the cockpit was to be pressurized. Turbochargers were just starting to really become common, while this aircraft was the first fighter designed from the ground up with a pressurized cockpit, so the XP-62 was a relatively advanced aircraft.

In August of 1941 some changes in the proposal were specified: the 1537 lbs. in weight were to be added, the top speed was dropped to 448 mph, and the armament was finalized at 8 20mm cannon. Design work continued into 1942, but the aircraft went through several redesigns, mainly aimed at cutting weight. Eventually the XP-62 shed some 1500 lbs., through structural redesign, dropping 4 of the cannon, and removing a propeller de-icing system. The USAAF placed an order for 100 on May 25, 1942, but then cancelled that order on July 27, 1942. The cancellation was issued because the production of the P-62 would have interfered with the Curtiss licensed production of essential Republic P-47s. Implied in this reasoning is the fact that by July 1942 the U.S. really had no need for a high performance interceptor. We were already gearing up for offensive weapons to take the fight to the enemy.

However, this wasn't the end for the XP-62. Final design and work on the XP-62 continued. Chronic problems with the pressurized cabin led to the decision to fly it without the cabin installed. The XP-62 had its first flight on July 21, 1943. Flight testing proceeded slowly due to the XP-62's low priority, and in the autumn of 1943 it was scrapped.

The XP-62 is an interesting "what if." While the extremely short flight test period resulted in few performance specs, the estimated ones compare favorably with the top interceptors of the war, the Fw-190-D9 and its sister bird, the Ta-152. Considering these aircraft were designed 2-3 years after the XP-62, that is no small feat.

P.S.- Sorry for the lack of pictures this week, but one problem with doing rare aircraft is that there aren't many pictures available. I promise more next week, including some gratuitous FFAR shots.

Up next week, we'll look at some interceptors from another era, the rocket-armed Northrop F-89 Scorpion and the Lockheed F-94 Starfire.