By employing the gaseous oxygen as oxidizer and gaseous hydrogen as fuel

hot-firing tests were performed for aerospike nozzle and dual-bell nozzle test engines with altitude compensating features.The gaseous hydrogen/oxygen experimental system

the test nozzles' configuration

design parameters and assembly graphics were described.Made of the ablation-resistant tungsten-copper alloy

the test components of nozzles have successfully passed several short-period hot-firing tests.The measured parameter curves

test photographs and results are obtained

thus obtaining the performance data of aerospike nozzle and dual-bell nozzle under different altitudes

both of which have good altitude compensation characteristic as compared with the conventional bell nozzle.For example

the thrust coefficient efficiency of aerospike nozzle is 92%-95% and dual-bell nozzle is 96%-98% at low altitude

and about 95% at high altitude.