Summary
- Safran Silvercrest engine’s poor performance led to the cancelation of the Citation Hemisphere, causing certification delays and airflow issues.
- Textron’s lack of alternatives with suitable thrust-to-weight ratios for the Hemisphere program further solidified the cancelation decision.
- Besides engine issues, canceling the Hemisphere was also influenced by market timing, resource allocation decisions, and the loss of platforms for Safran’s Silvercrest engines.
The Cessna Citation Hemisphere, a highly anticipated large-cabin business jet from Textron Aviation, was ultimately canceled due to a combination of technical and economic factors. The primary reason was the persistent performance issues with the Safran Silvercrest engines, but other contributing elements also played a role. The Hemisphere project remains “suspended” indefinitely, and Textron has shifted its focus to other aircraft programs, such as the Citation Longitude, Denali (now Beechcraft Denali), and SkyCourier.
The cancelation of the Cessna Citation Hemisphere
Engine Performance Issues
The most significant factor in the cancelation of the Citation Hemisphere was the under-performance of the Safran Silvercrest engines. Textron selected the Silvercrest engines for the Hemisphere due to Safran’s promise of better fuel efficiency and lower noise levels. However, several issues plagued their development.
Photo: Textron Aviation
During high-altitude tests, the Silvercrest engines exhibited slow acceleration and engine deceleration. The engines exhibited poor response to control inputs. The primary problems with the Silvercrest engine were related to its high-pressure compressor (HPC). The HPC experienced pressure losses and reduced performance during high-altitude tests. These issues are traced back to the axial-centrifugal architecture of the Safran Silvercrest HPC.
Core engine airflow and Heat Exchanger problems
During initial flight tests, Textron test pilots reported airflow issues through the engine’s core. The phenomenon resulted in erratic engine performance and a failure of the engines to maintain thrust setting inputs. This problem likely contributed to the overall performance deficiencies and may have been related to the compressor issues.
The Silvercrest engine also encountered heat exchanger problems early in the development process. While less emphasized in later reports, this issue contributed to the initial delays and technical challenges.
Certification Delays
The engine’s performance issues led to significant delays in its certification schedule. These delays made it impossible for aircraft programs like the Dassault Falcon 5X to meet their planned entry into service dates.
Photo: Safran Silvercrest
Thrust and Weight Concerns
For the Citation Hemisphere program, Textron noted that replacing the Silvercrest with a heavier engine or one that would struggle to deliver the necessary thrust was not a viable option. This suggests that the Silvercrest engine’s power-to-weight ratio was a critical factor in its selection, and its failure to meet performance targets left no suitable alternatives. Textron put itself into a critical dilemma when it failed to anticipate the need for a powerplant “Plan B.”
HPC redesign failed to correct performance deficiencies
Safran redesigned the vexed HPC after discovering performance issues during early flight trials. Although the redesigned HPC exceeded expectations in some respects, further trials were necessary to confirm overall engine performance and durability. However, ultimately, the redesign failed to sufficiently correct the problems encountered with the Hemisphere flight test program. Safran’s inability to resolve these issues promptly led to significant delays in the overall project timeline.
An alternative engine is briefly considered
When it became clear that the Silvercrest engine faced significant performance issues, Textron Aviation surveyed the industry for an alternative powerplant for the Citation Hemisphere. The only notable potential alternative was the Pratt & Whitney Canada PW800 series engine. This engine initially seemed to make sense because it offered greater power output and could potentially meet the specifications of the Hemisphere.
However, the PW800 powerplant’s thrust-to-weight ratio was lower than that projected by Safran for the Silvercrest. The PW800 turbofan had the power but at the cost of a greater weight. Ultimately, Textron put the Hemisphere program on hold due to unresolved issues with the Silvercrest engine and its critical role in the aircraft’s design and performance targets.
Market and Competitive Landscape
While the engine issues were the main reason, the competitive landscape and market conditions also influenced Textron’s decision.
Market timing
Cessna initially announced the Hemisphere program launch in 2015, with an expected entry into service by 2019. Delays in engine development pushed this timeline further, making it difficult for Textron to justify continued investment without a clear path forward.
Specification |
Cessna Citation Hemisphere |
---|---|
Max Takeoff Weight (MTOW) |
39,600 lbs (17,962 kg) |
Range |
4,500 nautical miles (8,334 km) |
Maximum Speed |
Mach 0.9 |
Cabin Height |
6 ft 2 in (1.88 m) |
Cabin Width |
8 ft 2 in (2.49 m) |
Cabin Length |
30 ft 7 in (9.32 m) |
Seating Capacity |
Up to 19 |
Service Ceiling |
45,000 ft (13,716 m) |
The Silvercrest problems jeopardized the Hemisphere order book, including a 150-aircraft order from launch customer NetJets, further diminishing the project’s viability.
Strategic Focus and Resource Allocation
In contemplating the fate of the Hemisphere, Textron had to make strategic decisions about where to allocate its resources most effectively. Ultimately, it decided to refocus on other projects, such as the super-midsize Citation Longitude, the SkyCourier, and the Denali programs, which were closer to fruition and had more apparent paths to market entry.
Although Textron ostensibly left the door open for a potential reboot of the Hemisphere program, contingent on future market conditions and the availability of a suitable engine, there is no indication that the company is considering a resuscitation of the design.
Loss of Platforms
Canceling the Hemisphere also had broader implications for Safran’s Silvercrest program. The Silvercrest engine performance debacle caused the loss of both its intended platforms—the Dassault Falcon 5X and the Citation Hemisphere. When the Citation Hemisphere program was suspended, Dassault had already moved on to the Falcon 6X, powered by Pratt & Whitney PW812D engines.

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