Thrust measurement experiment was carried out using a four-cylinder pulse detonation rocket engine (PDRE) with a rotary valve. The PDRE uses three types of gases, oxidizer, fuel, and purge gas to generate detonation wave intermittently and produces thrust. A rotary valve attached coaxially to a motor for supplying these three gases intermittently was used. The mechanism of the rotary valve is very simple. It is built up with a top cover, a rotating disk, and a casing, and has advantage to enable high mass flow rate and high frequency operation. In this study, pulse detonation rocket (PDR) for flight tests was developed. Thrust measurement experiment by grand test was carried out to check the performance of the this PDR. The oxidizer was N 2 O, the fuel was C 2 H 4 , and the purge gas was He. In the operation time for 1500 msec with C 2 H 4 -N 2 O propellant, we achieved time-averaged thrust of 256 N and specific impulse of 130.8 sec. Nomenclaturef D = detonation generating frequency f exp = experimental operation frequency f M = motor operation frequency f PDE = 1 PDE cycle frequency per tube I sp = propellant-based experimental specific impulse m i = purge gas mass flow rate m p = propellant mass flow rate P exp = oxidizer exhaust pressure (pressure between rotary valve and detonation tube) p i = purge gas supply pressure p p = propellant supply pressure R = gas constant T = temperature t ope = operation time V = volume  = equivalent ratio  p = propellant fill fraction

Thrust measurement experiment was carried out using a four-cylinder pulse detonation rocket engine (PDRE) with a rotary valve. The PDRE uses three types of gases, oxidizer, fuel, and purge gas to generate detonation wave intermittently and produces thrust. We used a rotary valve attached coaxially to a motor for supplying these three gases intermittently. The mechanism of the rotary valve is very simple. It is built up with a top cover, a rotating disk, and a casing, and has advantage to enable high mass flow rate and high frequency operation. The oxidizer was N 2 O, the fuel was ethylene, and the purge gas was He. In the operation time for 1000 msec with C 2 H 4 -N 2 O propellant, we achieved time-averaged thrust of 258.5 N and specific impulse of 138.7 sec. Nomenclature f M = motor operation frequency f PDE = 1 PDE cycle frequency per tube f D = detonation generating frequency f exp = experimental operation frequency I sp = propellant-based experimental specific impulse m i = purge gas mass flow rate m p = propellant mass flow rate p s,i = purge gas supply pressure p s,p = propellant supply pressure t ope = operation time  = equivalent ratio  p = propellant fill fraction  p,i = propellant and purge gas fill fraction  = rotation angle of rotating disc Subscripts i = purge gas p = propellant s = supply

We designed a rotary valve for a multi-cylinder pulse detonation rocket engine (PDRE), and constructed a greatly simplified rotary-valved four-cylinder PDRE (inner diameter and length of detonation tube: 37 mm and 1,600 mm, respectively). The partial-fill effect of a propellant in a multi-cylinder PDRE under high-frequency operation was investigated. The suctioned-air fill fraction was estimated using the model of Sato et al., which is a semiempirical formula for the partial-