PTVC-M for Ultra-Agile VTOL and 300+ km·h<sup>-1</sup> Cruising

Abstract

There remains a need to develop improved VTOL techniques that are cost-effective and with minimum compromise on cruising flight performance for fixed-wing aircraft. This work proposes an elegant VTOL control method known as PTVC-M (pitch-axis thrust vector control with moment arms) for tailsitters. The hallmark of the approach is the complete elimination of control surfaces such as elevators and rudder. Computer simulations with a 1580 mm wing span airplane reveal that the proposed technique results in authoritative control and unique maneuverability such as inverted vertical hover and stall-spin with positive climb rate. Zero-surface requirement of the PTVC-M virtually eliminates performance tradeoffs between VTOL and high-speed flight. In this proof-of-concept study, the VTOL-capable aircraft achieves a VH of 360 km·h −1 at near sea-level. The proposed technique will benefit a broad range of applications including high-performance spinsonde that can directly measure 10-m surface wind, tropical cyclone research, and possibly serving as the cornerstone for the next-generation sport aerobatics.

Rotosonde: Acquiring Vertical Wind Profile of a Tropical Cyclone with Small Unmanned Helicopters

“…Thus far, the rotosonde investigated herein has been operating in autorotation mode with a descent rate of about 10 ms −1 . It would be of great interest to explore the concept of rotosonde in powered mode with the possibility of achieving a much slower descent rate or even a positive climb rate, similar to those accomplished by PTVC-M enabled spinsonde [8]. However, such detailed work is beyond the scope of this article and will be reported elsewhere.…”

“…Spinsonde-capable unmanned airplane with a wing loading of 227 g·dm −2 has a simulated descent rate of 9.8 ms −1 and a V H of 355 km·h −1 (without drop tanks) [7]. It is also interesting to note that unmanned airplane equipped with PTVC-M was able to climb while gyrating in the stall-spin [8]. Small unmanned helicopters (main rotor spans: 550 to 800 mm) are highly agile and have a reasonably good tolerance to gusty winds during flight and while docking on mobile carriers.…”

“…From 40,000 ft (12,192 m) down to sea-level, the descent rate of the dropsonde varied from about 28 to 11.5 ms −1 [2]. Spinsonde technique based on the stall-spin maneuver of fixed-wing aerobatic aircraft has recently been proposed and demonstrated to have the ability to measure vertical wind speed profile similar to a dropsonde [6] [7] [8]. The hallmark of the chute-free spinsonde approach is that it enables acquisition of multi-cycle measurement using only a single airplane and hence being cost-effective [6].…”