Firefly Aerospace, a new private aerospace company, at 6:59 pm on September 2nd, California local time, made its first test flight of its light rocket Alpha Firefly α at Vandenberg Air Force Base. The rocket successfully ignited and took off, but about 2.5 minutes later Explosion:
First look at the basic situation of the Firefly α Firefly Alpha rocket, 29 meters high, 1.8 meters in diameter, 2 meters in diameter of the fairing, and 1 ton of LEO capacity in low earth orbit.
This is the first test flight of the rocket. Their goal is only to send a test load of 92 kg to a low-Earth orbit with an altitude of only 300 kilometers.
The configuration of the Firefly Alpha rocket is two-stage into orbit. The upper stage rocket is powered by a Lightning 1 liquid oxygen kerosene engine with a vacuum thrust of about 7 tons.
The next stage rocket is powered by 4 Reaver 1 liquid oxygen kerosene engines with a total thrust of about 70 tons. It is understood that the Reaver 1 engine uses a relatively simple open cycle, but it is not the mainstream The fuel pump is driven by pre-combustion in different ways. The engine specifically pumps a part of the fuel gas from the combustion chamber to cool it and then drives the fuel pump to pump air circulation. That is, it is relatively simpler, lighter, and theoretically can have a higher thrust-to-weight ratio.
It should be noted that the number of engines in the rocket stage is only 4:
are evenly distributed in the four corners, and its protective shell can clearly show the vector swing amplitude of each engine. The angle is limited or even a fixed one-way swing:
If an engine fails, it is easy to cause yaw or even sway,
The first stage of the rocket must be shared by the four engines, in terms of flight control They are interdependent and indispensable, and the requirements for reliability are relatively high.
Look at the flight process again
expert Scott Manley can see the clues from its tail flame,
At about 25 seconds, one side of the tail flame appears discontinuous and the other side narrows , He analyzed that it might be that one of the engines stalled.
combined with the basic flight data, it can be seen that after 25 seconds, its speed did not increase, and the acceleration A (m/s^2) even showed a negative value:
It was obvious that something went wrong at the time, the rocket It's not strong enough, even the speed of sound hasn't reached. Firefly's team should be very aware that it is difficult to reach the intended orbit, so they tried to keep the rocket flying far to the Pacific Ocean.
However, from the perspective of the flight situation, the flight direction is difficult to grasp, and there is a situation of out of control of swaying and rolling:
In order to avoid unnecessary safety accidents, the personnel of the Delta 30 unit at the Vandenberg SLC-2W launch site took advantage of this situation. The rocket flew over the Pacific Ocean and detonated it decisively, terminating the test flight.
Afterwards, Firefly officials announced that although the test flight was not satisfactory, it was fortunate that there were no casualties.
Therefore, similar to my country's Hainan Wenchang and Florida, the launch point is close to the vast ocean still has the advantage of safety.
Coincidentally, on August 28, a private aerospace company, Astra, also conducted a rocket test, but it also failed. It also suffered from insufficient power, and even a classic and rare lateral movement phenomenon:
According to the official announcement, this LV0006 Rocket 3.3 rocket that took off in Alaska,This is the third test flight of Astra's Rocket 3 rocket with a LEO of only 100 kg in the second configuration. The first two failed. In this test flight, one engine stalled after it was started, and the rocket was unable to tip over as soon as it left the launch pad. Under extreme control, it drifted. At that time, many people thought this time as a "pill", but the staff quickly let the rocket take off with the remaining four engines afterburner.
Coincidentally, like Firefly’s Alpha rocket, Astra’s Rocket 3.3’s classic test fire was also artificially terminated in 2.5 minutes and also fell into the Pacific Ocean. But Rocket 3.3 flew with 48 kilometers high, and reached the Max-Q aerodynamic pressure peak, and even completed the secondary separation
Astra team obtained a lot of important flight data during this period . Kemp, one of the main creators of Astra, is also sincerely proud of the team:
If the final result of this Firefly investigation is also an engine failure, both companies have technically achieved timely automatic shutdown and shutdown under abnormal engine conditions. ; The attitude of the two rockets and the degree of automation of the flight control are relatively high, and there is no imbalance immediately when the flame is turned off, and the personnel's on-the-spot response ability is also very strong.
But the same power is lacking. Why did the Astra with dramatic translation finally outperform the Firefly with high driving and low driving in the two test flights:
In terms of the number of engines, both of them are less. , Firefly has 4 Alpha Rockets, all of which are indispensable.
But if Aatra's Rocket 3.3 lacks 1, its power loss is 20%; Firefly's Alpha Rocket 4 lacks 1, and its power loss reaches 25%.
In terms of engine distribution and vector swing range
Aatra's Rocket 3.3 5 engines have a larger adjustment range and a wider dispersion. After one engine fails, the remaining 4 engines are more daring to generate power, so they fly more. Faster and higher
Firefly Alpha rockets with only 4 engines are more important to each engine, and the remaining 3 need to sacrifice thrust to maintain balance. The vector swing range is limited and is greatly affected by air. Turning out of control or related to this:
Therefore, the rocket test flights of the two companies were also underpowered and ended in 2.5 minutes, but the performance and harvest were completely different due to the difference in power design.
Rocket Lab was founded in 2006. Its light electric pump rocket Electron with a capacity of only 300 kg uses up to 9 engines, and it was not until 2017 that was tested. After the first flight failed , The second flight was a success. Now including the first flight, Rocket Lab ’s electric pump rocket Electron has launched 21 times, 18 of which have been successful
The Falcon 9 rocket with 9 Merlin 1D engines has also been used in actual missions. In the case of a single engine shutdown, the remaining 8 engines still completed the mission (the first-level rocket was lost due to excessive fuel consumption and unable to land at the designated point).
Therefore, it can be seen that the design with high redundancy in power and control does help to improve the fault tolerance rate and increase the task completion rate.
And SpaceX strengthened this point, sacrificing some capacity to let Falcon 9 return.The Blue Origin Shepard rocket can also land vertically. In addition, Rocket Lab has also carried out a parachute landing experiment of surface fishing through the Electron rocket and achieved results.
However, for new companies such as Firely and Astra that have not yet got their rockets into orbit, it is very difficult for them to leapfrog recovery. Therefore, it is more pragmatic for them to develop light disposable rockets first.
And high redundancy is obviously not conducive to cost control of one-time rockets. For example, SpaceX's Falcon 1 rocket, which has a capacity of only more than 400 kilograms, only uses an open-cycle liquid oxygen kerosene engine Merlin 1, and the planned parachute recovery has not been tried.
The main way for companies such as Firely and Astra to grasp their price advantage is to reduce production costs.
For example, the Alpha rocket that Firefly flew in this test flight, in addition to using a simple engine, has also simplified the rocket body, which improves the utilization of composite materials, makes the body lighter and retains more capacity.
Although its LEO capacity is only 1 ton, it does not even have a tenth of the Falcon 9. But Firefly reduced the launch price of the Alpha rocket to $15 million per launch, which is already quite cheap.
Astra’s Rocket 3 rocket, which has a capacity of only 100 kg, has a smaller volume and a simpler electric pump for its engine. The target launch price is lower at 2.5 million US dollars. The delivery capacity is expected to reach one shot per day.
These are one to two orders of magnitude lower than the price of traditional rockets, which cost hundreds of millions of dollars, and even lower than the price of Falcon 9. However, the launch price per kilogram requires US$15,000 and US$25,000. In contrast, the LEO Falcon 9 with a recoverable capacity of about 17 tons, even if it is calculated at US$62 million before the price reduction.The launch price per kilogram is only more than 3,600 US dollars. In addition to the 60-round star chain , there is also a "carpool" operation of 88 and 143 stars.
But even if the Falcon 9 successfully recovers the first-stage rocket and a fairing, the launch cost will be more than 15 million. It also requires various supporting equipment and personnel such as unmanned ships and fairing recovery ships. And taking into account the possibility of recovering failed rockets worth more than 30 million yuan, the actual launch price of Falcon 9 is still more than tens of millions of dollars.
In terms of total price, it is still a light one-off rocket. The total price of is lower, and for light payloads such as cubic star, small rockets are more flexible and launch services can be more personalized.
SpaceX currently has no intention of exerting power on light rockets. It has stopped major improvements to Falcon 9, without mass production, and has not increased the frequency of carpooling. A lot of energy was put on the future heavy vehicles like starships.
And the starship project is still in progress. The upper-level spacecraft’s ultimate pull rod vertical landing and the recovery mode of robotic arm aerial grabbing are unprecedented, and the infrastructure requirements and investment compared with light rockets are completely different. The project as a whole It is more time-consuming, and the ultimate reliability of the vehicle is still unknown. Make the price all over the floor
Even after a few years, a large number of starships after flight are proven to be reliable, but there is still a high risk of landing on Mars. Guaranteeing the launch of the Mars fleet
Now Firefly and Astra, which have not even succeeded in their first launch, have won hundreds of millions of orders. After the starship proves itself, they may have developed or improved a lower-cost rocket
It is worth mentioning thatChina’s Blue Arrow Aerospace LEO’s 6-ton Suzaku 2 liquid oxygen methane rocket is progressing smoothly. The engine assembly has been completed at the beginning of the year. It is expected to make its first flight this year. span96span, its LEO hyperbolic No. 2 liquid oxygen methane rocket with a capacity of about 1.9 tons, in addition to its variable thrust engine completed the test run, it also passed the landing gear test on September 3 this year
It is obvious. The cost of methane is lower than that of non-renewable kerosene, and it is not easy to accumulate carbon. The engine is easier to be reused multiple times. I believe its price will be more competitive than the disposable kerosene rockets of Astra and Firefly in the United States
As the overall launch price of aerospace continues to decrease, it is believed that the cake in the aerospace market will become bigger and bigger, and there will be more and more test flights and launch missions in the future. Span96span
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