The most important active control element of the Zenith is the altitude-control airbrakes. Their angle is calculated by our custom flight computer and avionics to precisely slow the rocket to reach 835 feet exactly no matter the flight conditions with a precision servomotor and control linkages. The main housing for the airbrakes also serves as our TARC transition unit.

Zenith rockets carry two parachutes as part of our dual-deployment system. The ejection charge deploys the small drogue chute that pulls out the SPRS. Our main parachute will not deploy until the SPRS actuates, which is calculated by the flight computer and sent by a long umbilical cable on the shock cord to the SPRS system. This allows the Zenith to actively control its own descent rate and land within 41-44 seconds. As of Zenith 3/4, the SPRS has been replaced by a manually set parachute limiter that controls the descent rate.

Weathercocking issues in our Zoomer rockets have resulted in one thing: the Zenith Aft Unit. Precision is a breeze with three perfectly spaced NACA M1 airfoils and a one inch boatail to reduce drag combined into one 3D-printed unit, which also acts as a centering ring. Passive stability is augmented with each fin having a modified airfoil trailing edge to impart a spin stabilization on the Zenith as soon as it leaves the rail.

In the heart of every Zenith and Zoomer rocket is a flight computer; so far, four have been made. Zenith uses the 4th to 6th iteration boards to power computation and control. Horizons has progressed from rudimentary breadboards to our custom PCB prototypes with swappable core compute modules; each core module runs 10 times the speed of our Zoomer flight computers and 125 times the internal memory. Avionics are connected to these FCs through the PCB, and log/process acceleration, gyroscopic, and altitude data 40 times a second to an SD card and for active control.

Made out of second-generation prototype quality parts, Zenith Boilerplate was built for fit checks with the launch pad, airbrakes, release system, Booster 1 and Flight Computer 4. It was then painted in the Horizons colors and decals and is currently used for marketing and display purposes. It shares the same aft unit and nose cone design as its successors, but uses PETG as the material, and lacks its own airbrakes and internal structures.

Horizons' first TARC rocket, Zenith IA was designed from the onset to carry two simulated eggs in a boilerplate egg holder and features initial or improved versions of all the flight systems of the Zenith and Zoomer programs, including our first altitude-control Airbrake design and SPRS. Zenith IA was launched on 10/9 with a F50-6T engine to 950 feet and was mostly successful, though the SPRS lost connection to Flight Computer 4 and thus the main chute did not deploy. Data gathered was used to improve flight-control firmware.

The Zenith IB class is an overall progression of the Zenith rocket. While the IB-class retains the same booster design as Zenith I, it features a shortened payload section, lengthened airbrakes, revised nose cone, additional nacelles, and foam egg protectors. All subsystems have been improved with data and user testing of Zenith I. It has launched once on an F51 motor and successfully exectuted its electronic recovery sequence to fully recover safely unlike Zenith I. Two more launchs are planned on 11/21 on larger F67 motors. The ZN1B was the first to feature swappable boosters, and flew with Booster 3.

The Zenith 2 class features a completely overhauled internal/airbrake system: the flight computer mount and the airbrakes have been combined into one lightweight unit, with larger airbrakes mounted onto the BT-80 payload tube. The use of two airbrake actuation motors allowed for more control precision and strength. Zenith 2A would utilize its swappable boosters to start with Booster 3, upgrading to the larger finned Booster 4, but eventually be phased out for the Booster 5+ design that rectified an issue with the large launch rail guides causing stability issues.

Zenith 2B used the same airbrake system as Zenith 2A but featured a new class of swappable Booster: Booster 5. Zenith 2B's ascent was perfect unlike its unstable precessors thanks to new low-friction launch rail mounts, but it landed to its doom in the ocean. An unknown issue prevented SPRS from deploying, thought 2B's flight computer was the first to incorporate the deployment algorithm for flight duration.

Zenith 3 is Horizon's qualification-class rocket, which can use the Booster 6+ design. Thus, ZN3 can be swapped to using any of the Horizon Booster 6,7,8, or 2X fleet. After testing and one launch it was determined it needed an upgraded airbrake unit with deeper and stronger control at the cost of deployment range. A massive improvement for Zenith 3 is the use of rivets instead of tapping screws for retention of components, allowing for a quick stacking procedure. Internal mounting of SPRS has also changed to facilitate parachute behavior. Zenith 3 has the most launches under its belt out of every Horizons rocket. In March, the airbrake was upgraded to the B design (MK4.3) which rectifies structural issues with the shock cord and also removes the SPRS system in favor of manual adjustment. ZN3 will be 1st in line for a qualification flight. ZN3 has only been stacked on the silver Booster 6.

After the qualifications, Zenith 3 is currently used as a display piece for outreach events. Plans are to donate the rocket for display at the local school.

Zenith 4 is the sister rocket of Zenith 3 sharing all the same components, though it was finished before Zenith 3 and had its maiden launch before. After testing and one launch it was determined it needed an upgraded airbrake unit with deeper and stronger control at the cost of deployment range. Similar to ZN3, the airbrake was upgraded to the B design (MK4.3) which rectifies structual issues with the shock cord and also removes the SPRS system in favor of manual adjustment. It serves as Horizon's backup qualification rocket and is typically stacked on the Orange Booster 7.

After the qualifications, Zenith 4 is currently used as a display piece for outreach events.