The ARRC's Space Program Thread

stoa1984 · February 17, 2023, 2:52am

HTTP-3AT hybrid propellant rocket tethered hovering flight

Demonstration of tethered hovering flight of HTTP-3AT hybrid rocket

Highlights

• Demonstration of the first-ever hovering flight test using hybrid rocket engines.
• Preliminary verification of the capability of the vertical landing of hybrid rocket.
• Validation of precise thrust control of the hybrid rocket engine.
• Controlling the oxidizer mass flow rate by using an industrial ball valve.
• Validation of direct-drive TVC for the hybrid rocket engine.

Abstract

This study demonstrated the performance of flight control systems of a hybrid rocket in a hovering flight test by developing a rocket designated HTTP-3AT powered by High Test Peroxide (HTP, a term used for concentrated hydrogen peroxide, H2O2).

Hybrid rocket excels in system simplicity, operational safety, oxidizer storability, cost, and throttling capability compared to current solid and liquid rocket engine systems. Although issues such as the severe oxidizer-to-fuel (O/F) ratio shift during combustion and difficulty in gimbaled thrust vector control (TVC) caused by the lengthy chambers need to be solved, hybrid rocket propulsion is nevertheless a promising propulsion technology for future space exploration. To achieve accurate orbit insertion, thrust magnitude control and TVC of the rocket engines are necessary. However, no organizations have successfully implemented this technology on a practical hybrid rocket, not even using this technology for hovering flight tests.

On September 8th, 2020, a hovering flight test of HTTP-3AT was conducted, achieving a steady hover 3 m above ground for 25 s utilizing both attitude and position controls. This test showed that a hybrid rocket could achieve a stable hovering flight with the capability of vertical takeoff and vertical landing (VTVL), demonstrating excellent throttling control and TVC capabilities of hybrid rocket propulsion.

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▲ HTTP-3A S2_HTTP-3AT 6th Tethered Hovering Flight Test; May 9, 2022; 1m47s

HTTP3A S2 hybrid propellant sounding rocket

–HTTP-3A Project–

HTTP-3A Stage-2

▲ Coming up next, we aim for a test flight of HTTP-3A second stage!

▲ The HTTP-3A S2 Rocket launch mission in Macaran, Taiwan; Will be launched next time due to the weather and rocket system issues.

▲ The HTTP-3A S2 Rocket launch mission in Macaran, Taiwan. We finally launched a rocket with autonomous attitude and trajectory control, and verified that our “ZIYASim” 6-DoF simulator developed in-house is highly accurate.

Debriefing

After 2 years, at 6:12 am on July 10, 2022, the HTTP-3A S2 rocket successfully lifted off, completing the second phase of the flight test project of the HTTP-3A rocket program. Although the flight altitude is not high, the main test purpose has been achieved.

The HTTP-3A rocket program can be divided into three phases of flight testing.

Phase 1: HTTP-3AT Suspension Flight Test
2020/08/20 5th Suspension flight test
2020/9/8 6th Suspension flight test

Phase 2: HTTP-3A S2 single-section flight test
2022/7/10 HTTP-3A S2 flight test

The third stage: HTTP-3A double-stage rocket full-flight test

It is a pity that this flight test did not achieve 100% of the original mission objectives. Of course, everyone has a different definition of success, but for the complete HTTP-3A mission objectives, it is already 99% successful. The main reason is that it is finally possible. to the next stage of flight testing.
This test situation is similar to the results of the 2021/11/03 HTTP-3A S2 vertical ground test. With limited resources and time, it is impossible to ensure that each test item is tested until 100% of the target is reached before proceeding to the next stage of testing. project.
However, the data obtained through the test can still undergo considerable review and improvement, and evaluate whether the next stage of testing can be directly carried out to achieve the required improvement and test verification items.

The main reason for the failure of the original flight goal for HTTP-3A S2
This flight test took only 80 seconds from launch to landing in the sea. The main reason is that the rocket engine stalled prematurely. After analyzing the cause, it was confirmed that the scale unit used for filling the oxidant was changed from the original kg to lb. This means that the rocket’s oxidizer is only filled to 45% of what it was supposed to be. If the filling is insufficient, the rocket will not have enough oxidizer for the engine to burn, so it will shut down early.
Although this kind of unit error problem (Supplementary Content 1) that also occurred in NASA should be taken as a warning, it still happened like Murphy’s Law. This part of the launch procedure will be discussed in detail to avoid the same situation from happening.
Surprisingly, even with such a large deviation from the initial value of the rocket, the rocket flight control still works normally.

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HTTP3A hybrid propellant sounding rocket

–HTTP-3A Project–

HTTP-3A Stage-1 + Stage-2

▲ HTTP-3A hybrid propellant rocket schematics.

Apogee 110km, retrieval of payload with the use of drone

▲ HTTP3A hybrid propellant sounding rocket flight profile.

HTTP3A hybrid propellant orbital rocket

Ground track of the HTTP3A hybrid propellant orbital rocket, similar to the Paektusan-1 SLV: first NOTAM zone at ~200 km downrange and spacecraft separation at~1’600 km downrange.

Also plotted, a dogleg to a sun-synchronous orbit.

▲ HTTP3A hybrid propellant orbital rocket ground track.

HTTP4 hybrid propellant VTVL sounding rocket

▲ VTVL (Vertical Takeoff and Vertical Landing) hopping flight tests with HTTP4 in 2022.

TBC…

stoa1984 · February 21, 2023, 4:18am

The ‘HTTP-3A’ suborbital rocket first stage is comparable in thrust to the Hapith V (Kestrel) SLV third stage.

The ‘HTTP-3A’ suborbital rocket first stage is powered by four ‘Tsuâ-Ing 5’ N2O/Thermoplastic Hybrid Rocket Engines of 13 KN each.

The Hapith V (Kestrel) SLV third stage is an upper stage with a single Lelien 1A N2O/Rubber hybrid rocket engine with gimbaled thrust vector control. It produces 9.8 kN of thrust (2200 lbf). The roll control of the upper stage is managed by an N2 cold gas reaction control system (RCS).

▲ 2. Tsuâ-Ing 5 Hybrid Rocket Engine Hot-Fire Test. May 22, 2022

▲ 2. Successful Hapith V Second Stage level Qualification Hot fire Test with Thrust Vectoring. Nov 20, 2019