Acme S-1 Sierra: Torrance's native pusher airplane

As I've long recognized, the Western Museum of Flight in Torrance is ubiquitous for housing a variety of aircraft built in the Los Angeles basin, including those made by Northrop as well as Radioplane (renamed Northrop Ventura in 1962). However, unknown to most aviation enthusiasts, this museum happens to have a very exotic homebuilt airplane on display, built at the very airport in Torrance near which the Western Museum of Flight is located, the Acme S-1 Sierra. Therefore, I am dedicating this post to discussing this unusual homebuilt pusher-engine aircraft from Torrance.

The Acme S-1 Sierra (aka "Sierra Sue") on display at the Western Museum of Flight. Photographed by me on April 21, 2024.

In the late 1940s, two former employees for North American Aviation, Ron Beattie and Walt Fellers, who came to work for the Northrop company after the end of the World War II, proposed a single-seat high-performance aircraft to meet Goodyear Racing Plane specifications and investigate the advantages of an airplane utilizing a pusher propeller layout. This design featured a teardrop-shaped fuselage and a Y-shaped tail empennage with ruddervators on the upper fins, and it had straight wings midway up the fuselage, and large air scoops placed at the forward ends of the wing roots. It was 20 feet 2 in (6.14 meters) long with a wingspan of 18 feet (5.49 meters), an empty weight of 590 lb (268 kg), and a top speed of 200 mph (322 km/h), and power came from one 85 hp (62 kW) Continental O-85 4-cylinder horizontally opposed piston engine situated behind the cockpit and driving a tail-mounted two-bladed pusher propeller. The Acme Aircraft Company based in Torrance, California, was entrusted to build the aircraft, and when this plane was completed in late 1948 it was now called the Acme Sierra, bearing the civil registration N12K (although this aircraft was sometimes nicknamed "Sierra Sue"). The first flight of the Acme Sierra occurred on November 23, 1953, and when Acme Aircraft was renamed Sierradyne Incorporated that year, the Acme Sierra itself received the internal designation S-1.  

The Acme S-1 Sierra at an airfield in Hawthorne in 1967 after being acquired by Northrop for testing the configuration of the N-308 attack aircraft project and rebranded as Northrop Turbo-Pusher (courtesy of Aerofiles).

Although it was not entered in any air races, the S-1 Sierra obtained extensive aerodynamic data during flight testing suggesting some aerodynamic benefits of a pusher-engine aircraft. During the 1960s, it was used by Sierradyne for tests of the aerodynamic benefits of the boundary layer control concept advocated by Swiss-born American aerodynamicist Werner Pfenninger and supported by Northrop. When the US Air Force in the late 1960s began contemplating plans for a purpose-built ground attack aircraft (which led to the A-X requirement), Walt Fellers in 1967 conceived a pusher-engine proposal for Northrop for the A-X program, the N-308, and that same year Northrop acquired the S-1 Sierra for use as a technology demonstrator to test the pusher-engine layout of the N-308, re-labeling it as the Northrop Turbo-Pusher. The S-1 Sierra's final flight ended in mishap on November 24, 1967, when its pilot created so much overload failure by improper operation of the flight controls and/or airbrakes that he crashed-landed the aircraft after a demonstration flight at Langley AFB in Virginia.

By 1970, Northrop dropped the N-308 in favor of the twin-turbofan N-312 and N-320 proposals for the A-X program after the US Air Force judged a turbofan-powered ground attack aircraft to be much faster than its inventory of A-1E Skyraiders compared to a turboprop-powered design, and the N-320 was designated YA-9 after being selected by the Air Force along with the rival Fairchild Republic A-10 for prototyping (the YA-9 itself ended up losing the A-X competition to the A-10 in 1973, but that's another story). Meanwhile, the S-1 Sierra which had ended its flying career as a technology demonstrator for the N-308 was eventually spared from scrapping and found a home at the Western Museum of Flight, which was initially based in Hawthorne before relocating to its present location in Torrance, the very city where the S-1 Sierra was built. 

References:

Chong, T., 2016. Flying Wings & Radical Things: Northrop's Secret Aerospace Projects & Concepts 1939-1994. Forest Lake, MN: Specialty Press.

Underwood, J.W., and Caler, J., 1958. Experimental Light Aircraft and Midget Racers. Fallbrook, CA: Aero Publishers.

Burbank's flying classroom for Canada: The Silver Star

During the near end of my visit to the Planes of Fame Museum in Chino last month, I happened to notice a jet aircraft inside the USS Enterprise Hangar, and the appearance of this airplane was so familiar to me that I wondered if it was a P-80/F-80 Shooting Star jet fighter or the T-33 jet trainer derivative. Oddly, this machine has the vertical stabilizer marked with a civil registration rather than a serial number, so I was curious about its manufacturing and operational history, and after doing online research, it occurred to me that the aircraft with civil registration N133AT was indeed a T-33, albeit a Canadian-built version known by the Canadian military designation CT-133. Given the superfluous operational history of the aircraft which is currently marked N133AT and emblazoned with in US Air Force markings, but also the fact that the T-33 was built under license in Canada, I'm dedicating this post to encapsulating the full history of the T-33 in Canadian service.

A Lockheed T-33A Silver Star Mk. 1 (serial number 14679) at RCAF Chatham in New Brunswick, initially built for the US Air Force with serial number 50-1275.

In the late 1940s the Royal Canadian Air Force was shopping for a jet aircraft able to provide advanced training for its fighter pilots due to the lack of a two-seat trainer version of the F-86 Sabre jet fighter that would be built under license by Canadair and enter service with RCAF fighter squadrons in 1950. After much consideration, the RCAF selected the T-33 to fulfill advanced training needs, and from May 1951 to March 1952, twenty T-33As were obtained second-hand from the US Air Force by the RCAF and assigned the serial numbers 14675/14694, followed by delivery of ten more T-33As were in late 1952 with the serials 516713/516717 and 516743/516747, and these T-33As were dubbed the Silver Star Mk. 1 by the Royal Canadian Air Force. Some of Silver Star Mk. 1 aircraft were later returned to the US Air Force in 1953-1955, but many remained in service with the RCAF until early 1955, when they were retired from service and later transferred to the air forces of Greece and Turkey.

A CT-133 Silver Star Mk. 3 (serial number 21326) in flight 

While the Royal Canadian Air Force began taking deliveries of its first T-33s, in 1951 the homegrown Canadian aircraft company Canadair received a contract to build the T-33 under license, and it assigned the company designation CL-30 to the Canadian version of the T-33, which differed in being powered by a Rolls-Royce Nene 10 turbojet rather than the Allison J33 that powered the T-33. One T-33A (serial number 51-4198) was modified by Lockheed to serve as the prototype for the CL-30, and upon delivery to the Royal Canadian Air Force on November 27, 1951, it was christened the Silver Star Mk. 2 and given the RCAF serial 146595. Lockheed referred to the Silver Star Mk. 2 as the T-33AN-X, and the CL-30 version was known as the T-33AN. On December 22, 1952, the first Canadian-built T-33 made its first flight at Cartierville, Quebec, with test pilot William S. Longhurst at the controls, and deliveries of CL-30/T-33AN to the Royal Canadian Air Force began in 1953 and lasted until 1959, by which time a total of 656 T-33s had been built under license by Canadair. The T-33AN, which became known as the Silver Star Mk. 3, was designated CT-133 by the RCAF, which allocated serial numbers 21001/21656 to the CT-133s. 

The CT-133 had an extremely long service life with the Royal Canadian Air Force. In addition to being the RCAF's premier jet trainer throughout the 1950s and 1960s, it also served with the RCAF's Red Knight aerobatic display team, and CT-133s used by the Red Knight aerobatic team were painted red. The baseline unarmed CT-133 variant was called Silver Star Mk. 3PT, and one variant of the CT-133 was built for gunnery and bombing training, the Silver Star Mk. 3AT, whose armament comprised two .50 caliber Browning machine guns in the nose and underwing pylons for 1,000 lb (454 kg) bombs and HVAR rockets. More than 100 CT-133s were built as Silver Star Mk. 3ATs, and several Mk. 3PTs were converted to Mk. 3AT as well. The Silver Star Mk. 3PR was a photo-reconnaissance variant equipped with photographic reconnaissance equipment in the nose, and one CT-133 (serial number 21257) was built as a Mk. 3PR in 1954, while four existing CT-133s were converted to Mk. 3PR standard in 1963-1964. Other non-training uses of the CT-133 included target towing, threat simulation, and ejection seat testing; the designations ET-133 and TE-133 were allocated to CT-133s optimized for simulating aerial and anti-ship threat simulation respectively, while CT-133s modified as ejection seat testbeds bore the designation CX-133. 

When the newer Canadair CT-114 Tutor jet trainer entered service with the Royal Canadian Air Force in 1963, the RCAF began the phaseout of the CT-133 from training squadrons, and the retirement of the CT-133 from active training duties was completed by 1976. The Red Knight aerobatic team, for its part, replaced its CT-133s with the CT-114 in July 1968 (by which time the RCAF's training units had become the Training Command), although the aerobatic team itself disbanded in 1969 as a result of budget cuts and personnel reductions. Beginning in 1958 and continuing until the 1980s, more than 200 CT-133s were sold to Bolivia, France, Greece, Portugal, and Turkey after being retired from service with the RCAF in the 1950s and 1960s. There were still over 50 CT-133s serving the Canadian Forces well into the 1990s, and nine CT-133s were redesignated CE-133 in 1994 after being modified for electronic warfare training. They were fitted with new avionics as part of the AUP (Avionics Upgrade Program) modernization process from 1996 to 1999, but the majority were eventually phased out in 2002. The Canadian Forces finally retired the CT-133 Silver Star Mk. 3 from service on April 26, 2005, when four remaining examples were phased out by the Aerospace Engineering Test Establishment at CFB Cold Lake, Alberta.

Then and now: CT-133 serial number 21157 on the tarmac at a Royal Canadian Air Force base in Cold Lake, Alberta, 1958 (left); CT-133 serial number 21157 on display at the Planes of Fame Museum with civil registration N133AT, photographed by me on January 21, 2024 (right). 

The CT-133 which I saw at the Planes of Fame Museum last month was given the serial number 21157 when it was delivered to the Royal Canadian Air Force on November 20, 1953, and it also served as a target tug beginning in July 1958. In March 1965, this aircraft was retired from service and eventually sold to numerous civilian owners with the civil registration N155X, which was later changed to the current civil registration N133AT, and it would occasionally be used as a camera ship for several movies. The CT-133 now registered as N133AT was listed for sale on the Internet in April 2006 but it ended up being acquired by aviation enthusiasts for restoration to static display at the Plames of Fame Museum in Chino, California, where it resides to this day.

F-104 Starfighters for Belgium

Much has been written about the operational use of the Lockheed F-104 Starfighter jet fighter with West Germany, Italy, and Japan, bearing in mind the fact that the F-104s operated by the Luftwaffe (the air force of West Germany and ultimately the reunified German nation) were given nicknames like "Flying Coffin" and "Widowmaker" because they suffered a high accident rate. However, almost lost in talk regarding the F-104's operational career with Western and Central European air forces is the service career of the F-104 with the Belgian Air Force.

A Belgian Air Force F-104G Starfighter (serial number FX-82) on outdoor static display at the Planes of Fame Museum, photographed by me on January 21, 2024.

In the late 1950s, the Belgian Air Force was shopping for a new combat jet to replace the subsonic CF-100 Canuck interceptors and F-84F Thunderstreak fighter-bombers in its inventory, especially given that both the Canuck and Thunderstreak were becoming technologically obsolete. With the Luftwaffe as well as the post-World War II Italian air force (Aeronautica Militare) and Royal Netherlands Air Force purchasing the F-104, the Belgian Air Force decided to order the F-104G, and contracts were signed for the purchase of 112 F-104Gs, with twelve TF-104Gs ordered from Lockheed and 100 F-104Gs to be built under license by the homegrown Belgian aircraft manufacturer SABCA. The TF-104Gs were given the serial numbers FC-01/FC-12 while the SABCA-built F-104Gs for bore the serial numbers FX-1 to FX-100; twenty-eight of the F-104Gs ordered by Belgium (three TF-104Gs, 25 F-104Gs) were funded under the Mutual Assistance Program (MAP). Deliveries of the F-104G to the Belgian Air Force began in February 1963, with the F-104Gs and TF-104Gs replacing the F-84F and CF-100 in service with the 23 and 31 squadrons (both of 10 Wing) at Kleine Brogel and the 349 and 350 squadrons (both of 1 Wing) at Beauvechain (Bevekom) respectively. One F-104G ordered by the Belgian Air Force (serial number FX-27) crashed during a training flight at Sart-Dames-Avelines on November 21, 1963 prior to delivery due to a flameout of the turbojet engine, and a new F-104G (c/n 9082) also bearing the serial number FX-27 was built and delivered to replace the crashed aircraft, so a total of 111 F-104Gs and 12 TF-104Gs were built for the Belgian Air Force.

Three Belgian Air Force F-104Gs (serial numbers FX-12, FX-30, FX-82) in flight, 1971. 

Operational use of the F-104G by the Belgian Air Force in its role as an interceptor began in August 1964. Although the 10 Wing and 1 Wing were exclusively tailored to the air defense and tactical nuclear strike roles respectively, the F-104Gs were swapped between the two operational wings to balance airframe fatigue between medium/high-altitude fighter missions and nuclear-armed fighter-bomber missions. In its role as a fighter-bomber for the Belgian Air Force, the F-104G was armed with B61 tactical nuclear free-fall bombs stored at facilities owned by the 52nd Special Ammunition Group at Meeuwen. By 1968, the F-104Gs of the 10 Wing switched to dual air defense/fighter-bomber missions and began training with conventional weapons such as the 20-mm Vulcan rotary cannon, three napalm bombs or two Snakeye bombs or two LAU rocket launcher pods each armed with nineteen 2.75-inch FFAR rockets. Beginning in late 1979, the Belgian Air Force began replacing the F-104G with F-16 Fighting Falcons (the TF-104Gs were phased out in 1980), and the last Belgian Air Force F-104Gs were retired from service on September 26, 1983. Besides the F-104G with serial number FX-27 that crashed in November 1963, a total of 38 F-104Gs and three TF-104Gs were lost in accidents during operational service. In the meantime, 18 Belgian Air Force F-104Gs were transferred to the Turkish Air Force and 23 were given to Taiwan.