Firefly withdrew from second launch attempt due to weather conditions

Firefly withdrew from second launch attempt due to weather conditions
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With the goal of successfully reaching orbit, Firefly is preparing to launch FLTA002, the Alpha launch vehicle’s second demonstration flight, in a mission called “To Land”. Launched from Space Launch Complex 2 West (SLC-2W) at Vandenberg Space Force Base in California, the vehicle is now scheduled to take off before September. 19 in a window between 3:00 am to 7:00 pm PDT (22:00 to 02:00 UTC).

A launch attempt on Sunday was canceled after a cancellation less than a minute before the window opened, followed by delays throughout the window. The teams then gave up another opportunity on Monday due to the weather.

FLTA002 will attempt to place several small satellites in a 300 km circular low Earth orbit (LEO) with an inclination of 137 degrees.

Firefly’s first orbital launch attempt It was terminated during the first stage burn in September. January 3, 2021, after an engine failure 14 seconds before launch. Despite this engine shutdown, the vehicle was able to maintain control for about two and a half minutes before tipping over, causing ground operators to activate the flight termination system.

Firefly was able to recover the range reduction of the engine assembly thus allowing them to understand that the engine was shutting down prematurely as the pins in the power line to the main engine valves failed causing the engine to shut down and shut down. This failure mode was backed up by data from the vehicle reporting a drop in current in the power rail and closing of the valve.

Firefly founder Tom Markusic noted that the engines in flight 1 were “rougher” than newer engines and therefore produced more vibration during flight. However, to be safe, the teams moved the electrical conductor higher in the vehicle where the vibrations were less intense, ensuring that the failure mode would not repeat itself.

Alpha is a small two-stage lift launch vehicle built and developed by Firefly Aerospace. With the aim of placing a load of 1,170 kg on the LEO, the vehicle stands at an altitude of 29.48 meters. Alpha has a significantly higher mass-orbit than other small satellite launchers such as the following. Rocket Lab’s Electron horse Astra’s Rocket 3, He has demonstrated placing up to 300 kg and 25 kg respectively in the LEO.

Alpha’s first stage is equipped with four Reaver 1 engines powered by RP-1 kerosene and liquid oxygen (LOX). Specifically, the Reaver uses the dispersal engine cycle, which means that pressure from the main combustion chamber is used, rather than having a separate gas generator to spin the turbines. However, this is still considered an open-cycle engine, as the exhaust gas used to turn the turbine is still exhausted.

Each Reaver engine generates a maximum thrust of 200 kN and achieves a specified 296-second stroke in vacuum. For rocket engines, the specific thrust of the engine is directly proportional to the velocity of the exhaust gas; The maximum average exhaust velocity for the Reaver is ~2,900 m/s.

Alpha’s first and second stages are made of carbon fiber composites that create ultralight unlined fuel tanks. Similar to the Falcon 9, both stages have the RP-1 tanks at the bottom, the LOX tank at the top, and a transfer tube to deliver the LOX to the engines.

FLTA002 vertical on SLC-2W before launch. (Credit: Michael Baylor for NSF)

The second stage is also equipped with a single Lightning 1 engine, a distribution engine cycle capable of producing 70 N of thrust.

The second stage has a carbon-composite charge coating on top. There are a few small payloads inside for “To The Black”. First, Teachers in Space will launch the Serenity 3U CubeSat, which will collect flight data during its mission and make it available to the education community.

FLTA002 also flies NASA’s TES-15 3U CubeSat, which has a deployable external brake that will be used to verify the center of mass systems for future reentries. This payload is NASA’s Technology Education Satellites program that gives students the opportunity to work on satellites.

The final payload will be Libre Space Foundation’s PicoBus, which will deliver six picosatellites. All of these satellites are technology demonstrators for communications, remote sensing and more.

Eight hours before launch, crews will begin their final pad checks. During this time, the Alpha vehicle will be powered and sensor checks will be carried out, which should be completed by the T-6 hour. At this point the vehicle will begin charging with helium, which is used to pressurize and backfill the tanks during ascent.

T-5 will start loading the vehicle with RP-1 in 15 minutes. After 45 minutes the pad will clear, causing the LOX load to begin at T-3 hours 40 minutes. The propellant charge will take up to 20 minutes before departure when the vehicle will enter the terminal count. At this point, the rocket will be fully refueled (with both the RP-1 and LOX) and continuously refueled with both propellants.

The four first-stage Reaver 1 engines will fire in T-1.8 seconds using TEA-TEB, a pyrophoric compound that means it burns on contact with oxygen. This glow will be bright green and will signal that the engines are running. Assuming the four engines and the vehicle are nominal, the ejection clamps separate from the vehicle’s floor, allowing the vehicle to lift.

At T+1:13 the vehicle will pass through the maximum aerodynamic pressure. At T+2:37, in an event called main engine outage (MECO), the four first stage engines will shut down before the stages separate and fire the second stage engine.

In less than a minute, the skin will be deployed at T+3:25. The second stage will then light up for another four minutes before shutting down at T+7:40. At this point, however, the mission isn’t over, as the stage will dock by T+53:57 and the engine will fire a second time, this time for two seconds. This will raise the first elliptical orbit to a circular orbit of 300 km.

Alpha will then deploy all three payloads and complete its mission at T+1:01:57.

If the mission is successful, Firefly hopes to launch FLTA003 in late 2022, which will likely become the ELaNa 43 mission for NASA.

(Lead photo: FLTA002 on foot before launch. Credits: Jack Beyer for NSF)

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