Differential pressure measurement using a free-flying insect-like ornithopter with an MEMS sensor

Abstract

This paper presents direct measurements of the aerodynamic forces on the wing of a free-flying, insect-like ornithopter that was modeled on a hawk moth (Manduca sexta). A micro differential pressure sensor was fabricated with micro electro mechanical systems (MEMS) technology and attached to the wing of the ornithopter. The sensor chip was less than 0.1% of the wing area. The mass of the sensor chip was 2.0 mg, which was less than 1% of the wing mass. Thus, the sensor was both small and light in comparison with the wing, resulting in a measurement system that had a minimal impact on the aerodynamics of the wing. With this sensor, the 'pressure coefficient' of the ornithopter wing was measured during both steady airflow and actual free flight. The maximum pressure coefficient observed for steady airflow conditions was 1.4 at an angle of attack of 30 degrees . In flapping flight, the coefficient was around 2.0 for angles of attack that ranged from 25 degrees to 40 degrees . Therefore, a larger aerodynamic force was generated during the downstroke in free flight compared to steady airflow conditions.

The Effect of the Phase Angle between the Forewing and Hindwing on the Aerodynamic Performance of a Dragonfly-Type Ornithopter

“…The weight of one wing was approximately 130 mg. The total weight of the ornithopter without the battery was 7.9 g, and the wing load was 4.6 N/m 2 , which is similar to that of dragonflies as shown in Table 1 and sufficiently light to fly with an external power supply [23,24].…”

“…The ornithopter was designed with a focus on actual flight possibility and was based on our previous ornithopters [22][23][24]. The forces on the wings were measured by microelectromechanical systems (MEMS) differential pressure sensors [25,26].…”

“…The MEMS differential pressure sensor detects the differential pressure between the upper and lower surfaces of insect-sized wings at pressure resolutions of less than 0.1 Pa. Differential pressure measurements have been obtained for a hawk moth-type ornithopter [23,24] or a real butterfly (Papilio protenor) [27]. In this study, the MEMS differential pressure sensors were mounted on the center of each wing.…”

“…Figure 1 presents the design and photographs of the fabricated ornithopter. The ornithopter was based on our previous ornithopter design [23,24] and was unique in that there were four wings with phase angles. The wing aspect ratio (wingspan/wing chord), Reynolds number, and reduced number were designed to match those of an actual dragonfly as shown in Table 1.…”

Stable vertical takeoff of an insect-mimicking flapping-wing system without guide implementing inherent pitching stability

“…However, research on flight stability of an insect is relatively limited compared with the number of studies available on their aerodynamics [25,26] . The main reason for this limitation is the difficulty in direct force measurement of an insect in free flight [27] . To overcome this situation, computational fluid dynamics was used to estimate aerodynamic forces produced by a bumblebee and their derivatives in Ref.…”