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To be economical, a VTOL airplane can be expected to have a higher gross weight than a STOL or CTOL. VTOL transports permit major reductions in total time for accomplishing a mission. ...VTOL transports permit major reductions in total time for accomplishing a mission. The VTOL system will be cheaper than STOL or CTOL for short mission accomplishment times. It is necessary to evaluate total savings resulting for shorter mission accomplishment times, but this is difficult because the ability to do things faster permits doing more things in a different manner.

While GE Aviation’s T700 turboshaft engine has powered the U.S. Army’s Apache and Sikorsky helicopters for more than 46 years, the U.S. Army will replace the T700 with GE Aviation’s fully modular T901-GE-900 engine as part of the Engineering and Manufacturing Development (EMD) phase of the U.S. Army’s Improved Turbine Engine Program.

This paper reviews the problems associated with developing a vertical takeoff and landing (VTOL) aircraft that has desirable helicopter-like attributes in hover and low speed operation but is capable of efficient high subsonic cruise speed. ...It is concluded that incorporation of variable geometry, in the form of a variable diameter rotor system, has the best chance of providing the “ideal” VTOL. The variable diameter tilt-rotor adds on the order of 100 knots to the speed potential of the tilt-rotor and provides numerous other benefits as well.

Future fighter aircraft requirements are likely to include a turn capability in excess of 7g's throughout much of the maneuver envelope, post-stall maneuverability, STOVL or VTOL, and a single engine for low cost.

The Joint Services Advanced Vertical Lift Aircraft (JVX) is intended to provide the Army, Navy, Air Force, and Marine Corps the ability to conduct combat, combat support and combat service support missions requiring vertical takeoff and landing capabilities not currently available. This multi-service and multi-mission application aircraft will maintain as much commonality as possible in meeting these objectives. This paper addresses the features and development of the propulsion system associated with the JVX.

Compared to helicopters, the safety and operational advantages of ducted fan VTOL vehicles that do not rely on large, exposed rotors overhead seem promising. The alternative to the overhead rotor that naturally comes to mind is a smaller, enclosed rotor or multitude of rotors, sometimes referred to as ‘fans’, or, in combination with their enclosure, ‘ducted fans’. ...During the 50's and 60's, numerous experimental VTOL vehicles were developed, that relied on ducted fans as their main source of lifting power. ...The present paper discusses these issues, as well as design parameters that offer potential for reduced operational cost and increased profitability of future commercially operated ducted fan VTOL vehicles. The paper also describes briefly one candidate vehicle that has the potential to meet these requirements--Urban Aeronautics' X-Hawk--a tandem lifting fan, twin turbine powered, VTOL utility vehicle, featuring among other things a fly-by-wire, closed-loop vane control system (VCS), enabling it to operate in rough weather conditions and obstacle rich environments.

The potentialities of VTOL systems are examined in terms of cost effectiveness. A comparison of VTOL, STOL, and CTOL systems shows that the operational cost effectiveness of the VTOL system is at least competitive, and is frequently advantageous. ...A comparison of VTOL, STOL, and CTOL systems shows that the operational cost effectiveness of the VTOL system is at least competitive, and is frequently advantageous. When the costs of ground facilities, ground access time, and social penalties are added, VTOL is seen to have a significant advantage over CTOL and STOL systems. ...When the costs of ground facilities, ground access time, and social penalties are added, VTOL is seen to have a significant advantage over CTOL and STOL systems.

One such potential is to develop a highly responsive low-medium jet propulsion engine that can finally make a jet-powered flying car practical and affordable, while paving the way for a new light-weight, jet-powered VTOL military assault vehicle. The pursuit of this viable concept to a successfully designed and functioning prototype of the Pulsed Turbine Rotor Engine will lead to opening a whole new chapter in aviation VTOL history. ...The pursuit of this viable concept to a successfully designed and functioning prototype of the Pulsed Turbine Rotor Engine will lead to opening a whole new chapter in aviation VTOL history.

This new method of VTOL flight appears to offer great promise to the commercial VTOL field, particularly as it applies to the interurban mass transportation problem.

By the early 21st century, high speed VSTOL aircraft will be operating in Air Transportation Systems around the world moving people and cargo to and from thousands of public use vertiports and stolports. Of even greater significance is the fact that high speed VSTOL aircraft will be playing a major role in reducing traffic congestion on the ground and in the air at busy hub airports. For many years world wide attention has been drawn to the United States' effort to develop the military V-22 Osprey. More than two billion dollars have been expended on this tilt rotor program. The advantages of a tilt wing over a tilt rotor, however, are beginning to surface in both the United States and abroad. The tilt wing, it turns out, is more efficient, more cost effective, safer and an easier aircraft to operate. Tilt wing development began in the mid 1950's. Successful demonstrator aircraft were the Boeing Vertol 76 VZ-2, the Hiller X-18, the LTV/Hiller/Ryan XC-142A and the Canadair CL-84.