Uploaded May 2026 | Updated September 2026, 4 hours ago
Future military missions for Agile Combat Employment (ACE) and next generation Special Operations Forces need an aircraft with effective hover and the ability to operate in transonic cruise. Hover requires significant power that can only be mitigated by larger diameter rotors, but large diameter rotors become a detriment to achieving transonic flight. The stop-fold rotor configuration can “make the rotor disappear” in cruise and stands out as the most viable option for meeting these next-generation air vehicle requirements. This presentation discusses the progress Bell has made in developing enabling technologies for a practical and scalable high-speed VTOL (HSVTOL) based on the stop-fold configuration. To this end, a unique Track-Guided Vehicle (TGV) was developed at Bell and tested at the 10-mile High Speed Test Track at Holloman Air Force Base. The test vehicle integrates all subsystems required to demonstrate the key technologies in a representative environment, including multi-mode propulsion, folding proprotors, and fly-by-wire transition controls to automatically manage each step of the prop-to-jet (and reverse) process. The TGV demonstration validated the stop-fold technical approach and generated critical data to substantiate engineering models. Test results provide confidence that each step in the stop-fold transition process is thoroughly understood and that engineering tools can be used confidently for future aircraft design efforts. Dr. Troy Shank's presentation documents the first known powered prop-to-jet and jet-to-prop transition and represents a significant milestone in vertical flight technology development.
Troy Schank is an Associate Technical Fellow at Bell Flight in the Advanced Programs group. He has worked at Bell for 18 years, primarily supporting various rotor technology development efforts, including integrated rotor sensing and active control programs. He has been the technical lead of Bell’s Stop-fold technology development efforts since 2015. He is currently a Co-Principal Investigator for the DARPA SPRINT program. Troy received a Ph.D. from the Georgia Institute of Technology in 2008.
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Are you interested in drones, helicopters, advanced rotorcraft and/or electric vertical takeoff and landing (eVTOL) aircraft? Are you having a hard time keeping up with the ever-changing landscape of the Advanced Air Mobility and Urban Air Mobility industry? Confused as to what eVTOL, VTOL, STOL, UAM, UAS, AAM, UTM… is and how it will impact you? Are you looking for serious facts and discussions concerning innovation and technology in the aerospace, rotorcraft, eVTOL, and helicopter industries? Search no more. The Vertical Flight Society is your global one-stop-shop for staying up-to-date and informed on all things vertical flight in this rapidly changing technological space.
Check out the Vertical Flight Society’s website at: vtol.org
Subscribe to all things Vertical Flight Society and vertical lift on YouTube at: youtube.com/user/VTOLSociety?sub_confirmation=1
#vtolsociety #helicopter #rotorcraft #VTOL #verticalflight
Looking for something specific? Check out these handy links:
• Membership: vtol.org/membership
• Vertiflite Magazine: vtol.org/vertiflite
• Press Releases: vtol.org/press-releases
• Technical Library: vtol.org/library
• eVTOL News: https://evtol.news
• Vertipedia: vertipedia.vtol.org
• Gallery: gallery.vtol.org
____________________________________________________________________________
VFS SOCIAL MEDIA
Stay up-to-date and in the know while on the go. Like and follow VFS on social media:
Facebook
• facebook.com/VTOLsociety
• facebook.com/electricVTOL
LinkedIn
• linkedin.com/company/vtolsociety
• linkedin.com/groups/3922985 (private group)
Twitter
• twitter.com/VTOLsociety
• twitter.com/ElectricVTOL
• twitter.com/DiversiFlite
Future military missions for Agile Combat Employment (ACE) and next generation Special Operations Forces need an aircraft with effective hover and the ability to operate in transonic cruise. Hover requires significant power that can only be mitigated by larger diameter rotors, but large diameter rotors become a detriment to achieving transonic flight. The stop-fold rotor configuration can “make the rotor disappear” in cruise and stands out as the most viable option for meeting these next-generation air vehicle requirements. This presentation discusses the progress Bell has made in developing enabling technologies for a practical and scalable high-speed VTOL (HSVTOL) based on the stop-fold configuration. To this end, a unique Track-Guided Vehicle (TGV) was developed at Bell and tested at the 10-mile High Speed Test Track at Holloman Air Force Base. The test vehicle integrates all subsystems required to demonstrate the key technologies in a representative environment, including multi-mode propulsion, folding proprotors, and fly-by-wire transition controls to automatically manage each step of the prop-to-jet (and reverse) process. The TGV demonstration validated the stop-fold technical approach and generated critical data to substantiate engineering models. Test results provide confidence that each step in the stop-fold transition process is thoroughly understood and that engineering tools can be used confidently for future aircraft design efforts. Dr. Troy Shank's presentation documents the first known powered prop-to-jet and jet-to-prop transition and represents a significant milestone in vertical flight technology development.
Troy Schank is an Associate Technical Fellow at Bell Flight in the Advanced Programs group. He has worked at Bell for 18 years, primarily supporting various rotor technology development efforts, including integrated rotor sensing and active control programs. He has been the technical lead of Bell’s Stop-fold technology development efforts since 2015. He is currently a Co-Principal Investigator for the DARPA SPRINT program. Troy received a Ph.D. from the Georgia Institute of Technology in 2008.
=================================================
Are you interested in drones, helicopters, advanced rotorcraft and/or electric vertical takeoff and landing (eVTOL) aircraft? Are you having a hard time keeping up with the ever-changing landscape of the Advanced Air Mobility and Urban Air Mobility industry? Confused as to what eVTOL, VTOL, STOL, UAM, UAS, AAM, UTM… is and how it will impact you? Are you looking for serious facts and discussions concerning innovation and technology in the aerospace, rotorcraft, eVTOL, and helicopter industries? Search no more. The Vertical Flight Society is your global one-stop-shop for staying up-to-date and informed on all things vertical flight in this rapidly changing technological space.
Check out the Vertical Flight Society’s website at: vtol.org
Subscribe to all things Vertical Flight Society and vertical lift on YouTube at: youtube.com/user/VTOLSociety?sub_confirmation=1
#vtolsociety #helicopter #rotorcraft #VTOL #verticalflight
Looking for something specific? Check out these handy links:
• Membership: vtol.org/membership
• Vertiflite Magazine: vtol.org/vertiflite
• Press Releases: vtol.org/press-releases
• Technical Library: vtol.org/library
• eVTOL News: https://evtol.news
• Vertipedia: vertipedia.vtol.org
• Gallery: gallery.vtol.org
____________________________________________________________________________
VFS SOCIAL MEDIA
Stay up-to-date and in the know while on the go. Like and follow VFS on social media:
• facebook.com/VTOLsociety
• facebook.com/electricVTOL
• linkedin.com/company/vtolsociety
• linkedin.com/groups/3922985 (private group)
• twitter.com/VTOLsociety
• twitter.com/ElectricVTOL
• twitter.com/DiversiFlite
