At each Inside Cirrus Event recently, we have on hand our newest airplanes including the Vision Jet, members of the executive team, colleagues from Garmin and Bose and more. After a brief multi-media "insider's view" of Cirrus, we open the floor to questions and comments. Because the conversations at these events are so important, we want to share some of them with everyone. So we are continuing post several of the more common topics we chatted with you about.
Feel free to contact us with additional questions and comments and be looking for information about the next Inside Cirrus Tour on the West Coast in the U.S. and in Latin America beginning in March 2011!
A: Paul Brey, Vice President – Product Development, is leading the Vision Jet Engineering Team and has been with Cirrus since 1996. Paul served in a similar role for both the SR20 and SR22 piston aircraft programs.
The recent focus on the Vision Jet program has been two-fold: first, address the highest risk systems on the airplane; and second, make steady progress such that the critical path design elements are minimized as we anticipate increased program funding.
Within these two areas, our attention has been on several items. A significant area of progress was working several flap iterations through flight test. We selected a two element, vaned flap on low complexity drop hinges (hinges below the wing surface). We validated stall performance in the mid/upper 60s knot range with acceptable control through all the power and flap configurations. Final flap span, aileron span and wing tip shape are now ready for type design.
We have refined the powerplant/airframe pitch response to high thrust inputs. Several design opportunities are yielding desirable results. The ability for this system’s response to be integrated for excellent handling and performance is now a reality and we are excited about how this particular area of engineering has progressed. We continue to optimize these design options and will soon select a combination that presents the best customer value in terms of performance, complexity and reliability.
Basic performance flight test is largely complete for the prototype aircraft (that we call V1). Stability, flying qualities and speed/range performance are validated and we are confident that the type design will exceed regulatory requirements and meet our planned performance goals. Wing aerodynamic loft is also fixed. In 2010, we completed a detailed computational fluid dynamics analysis and selected a de-cambered wing root loft that reduced drag substantially.
Analysis, dry ice shape and natural ice testing has been completed to establish final placement and extents of leading edge boots with good fitting offsets for minimal drag. TKS fluid coverage for the nose and windshield was iterated several times, and as a result of testing we now consider this item low risk. Heating extents on the engine inlet and duct have been determined by flight test. We will complete additional flight test this spring to optimize the heat areas and minimize bleed requirements, and will be in good shape to move forward with final inlet design with our partner, Meggitt.
Pictured above: V1 ice measurement devices in action. The sphere is used to measure droplet size and the blade is used to measure accretion rate.
In early 2010, we completed half-scale, proof-of-concept tooling to validate the single piece pressure hull fuselage construction concept. Numerous lay-up, bagging, tool sealing and curing iterations were completed allowing us to move forward confidently with the fuselage detail design. In addition, we tooled and built a full-scale fuselage pressure vessel for testing structural deflection and door performance. This test article was tested with a two piece door. The door frame, door structure, seals and latching scheme have been iterated several times and we are converging on a design we are confident will work well. Additional test iterations in 2011 will include windshield installation, door and passenger window installations and inclusion of the latching linkage actuation mechanism. The fuselage loft and door jamb loft designs have been frozen. The fuselage pressure vessel composite laminate drawings have been completed to about 80% maturity.
Pictured above: Pressure testing two-piece carbon door with window. Stress and deflection is measured with strain gauges and mechanical deflection indicators. Data is measured and recorded electronically in addition to the cameras recording the tests. The yellow strap is loosely fitted and is added as a test safety measure.
Carbon pre-impregnated composite material (pre-preg) suitable for commitment to long-term agreement for the Vision was selected as a result of 2010 work. Considerations in the screening and selection process included mechanical and thermal properties, processing characteristics, laminate quality, ultrasonic energy attenuation and cost. The final material selection is with a supplier that we have a working experience with, and is a new formulation that we believe provides the best performance. As a result of this work, we have also identified and trialed the non-destructive inspection (NDI) method we intend to use for each major part. This means that the NDI technology selected works and we understand the process capability. Most of the remaining NDI effort will focus on developing the robotics necessary to achieve the production throughput we have targeted. There are multiple suppliers of existing technology that will suit our needs and a down-selection program is underway. We anticipate full-scale testing starting with the Vision carbon stabilizer structure and both wing spars for certification credit during this year.
Adhesive system screening for structural bonding is about 33 percent complete as early 2011. Our suppliers have shipped the new formulations needed for specific Vision performance requirements. Testing and down selection will be completed in the second quarter, and the selected materials will be qualified in conjunction with the primary carbon/epoxy material.
Systems design continues to progress nicely. By the end of 2010, the Vision team completed Preliminary Design Review (PDR) of about two-thirds of the systems on the aircraft. Cirrus defines PDR in a manner similar to NASA and DOD systems engineering protocols and PDR is the most critical maturity milestone. This means that design architecture and main systems components are selected, safety and functional hazard assessments are complete, space claims and system design has been CAD modeled and the design has been approved for the next stage, which is detailed type design. We expect to continue to work through the rest of the systems in 2011.
As with the SR2X development, the Cirrus Airframe Parachute System™ (CAPS) remains one of the most complex systems and will require extra attention through the duration of the program. It is a very expense-intensive to mature and test the design, and full-scale system testing will occur later in the program. In order to reduce risk exposure, Cirrus tested scaled recovery parachutes in August 2010, and anticipates two more rounds of development testing in 2011. This testing is used to characterize the parachute performance over a range of sizes, weights, altitudes, reefing ratios and deployment speeds. This set of designed experiments allows interpolation and extrapolation of the parachute inflation characteristics and drag coefficients. This data is then used in modeling and simulation to understand the parachute loads and allow us to complete the fuselage design. As with the SR2X, the final design must be demonstrated by in-flight deployments. The development testing and simulation completed to date results in a higher confidence and more mature parachute design than we had available in the SR20 certification program in 1997.
Certification efforts continue to move forward at a steady pace. We have more than 90% of the ‘novel’ issue papers resolved, and we can establish our final certification basis within six months. Both our conventional approach to the design and our proposals for showing compliance to the FARs give us confidence that certification risks are low. This is a very significant positive status.
Finally, significant effort and progress has been made to secure further funding for Vision Jet completion and we expect to have more specific news on this topic soon. So, as we move into 2011, we are continuing our work toward making progress in key design and systems areas and reducing program risk. At the same time, we continue to refine our expedited plan in anticipation of additional funding.
Starting the expedited plan shifts the program from a technical risk phase - that we address through design, development, and testing - to an execution and program management risk phase. With additional capital in place, critical program elements that will be executed at higher rate are:
- Execution of supplier and risk sharing partner subcontracts
- Ramping up project technical staff and design partners
- Managing multiple large tooling vendors simultaneously
- Ramping up build and test technician staff to allow building three conforming flight test vehicles and a dozen major test article fabrications over a two year period
- Establishing a complex project planning and program control team
We are confident that the SF50 can be certified and in production within 36 months of additional anticipated capital funding.