Miura 5: everything we know about the PLD Space candidate to be the first Spanish orbital rocket

pld 1

PLD Space was the first Spanish company to present a private space rocket. Founded in 2011, this year it finally saw its Miura 1 take flight, but it is unable to put a satellite into orbit, that is what the Miura 5 is for. This new rocket under development is eligible for a contract with the Government of Spain of up to 45 million euros. But it is not alone, the extremely innovative Meso, from the Catalans of Pangea Aerospace, poses tough competition.

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The last available render of the Miura 5 was shown for the first time to those attending a press conference in Madrid. Photo: AstroAventura

Propulsion

The Miura 5 presents a power plant reduced to a minimum development. With the lessons learned from his demonstrator Teprel B, the greatest advance regarding this is the implementation of a turbopump. The system allows the acceleration of the fuel to the speed needed in the combustion chamber.

So far it seems quite simple, however, This device is the most complicated part of any rocket engine. It is responsible for more than half of space rocket accidents in the last times.

The Miura 5 is powered by a total of six engines., five would be employed in the first stage and one for the second. “The only difference between the first stage and second stage engines is that they are larger. In the first one, each one offers 150 kN, in total almost 1MN (Meganewton)” the head of development of the Miura 5, Raúl Torres, informed us.

He continued to develop this aspect a little further: “the First and second stage turbopumps are quite different. The first one is much larger. What they do share is fuel and engine is very similar although the second stage is adapted to vacuum.” Much of these differences will be based on a nozzle of a much larger size, which allows improving engine performance at low cost. This is the same philosophy applied by SpaceX to their engines where the big difference between the versions of sea level (first stage) and vacuum.

TEPREL
Image of a Teprel C. Source: PLD Space

There is more information about the fuel to be used than that made public by PLD. Despite his insistence to the media and fans, The body responsible for the contract was informed that they do not yet have biofuel. At the time a collaboration was announced with the Repsol oil company, which would supply biokerosene with the intention of reducing the environmental impact. Furthermore, in this way they would comply with the strict regulations DNSH (Do Not Significant Harm) from the European Commission, which requires palliative measures to be taken against the environmental impact. If not, projects financed by community funds, as is the case of the Spanish Microlauncher, they risk having their access to money cut off.

However, in the offer presented to the Center for Technological and Industrial Development, this appears not as a base feature, but as an incremental improvement to be implemented in the coming years. Even so, this is not very significant since this measure was only as a support, since a space rocket will contaminate in large quantities and exceptions are contemplated for these cases.

tober teprel B
Recent image that shows in detail the Teprel B nozzle. Source: Raúl Torres/RRSS

Beyond this technicality about whether it will be biokerosene or conventional kerosene, the officially confirmed mix to this means by the company, it will be kerolox. Specifically, RP1 type kerosene for rockets and cryogenic oxygen. In the case of kerosene, it will not be cryogenized as if they are carried out by other companies due to the extreme difficulties involved in managing two fuels in that state.

In summary, the Teprel C will be kerolox engines, with an open combustion cycle, a gas generator with a thrust of 150 kilonewton and a specific impulse of 275 seconds. A conservative design, which pleases the CDTI hiring table.

Teprel 1b
Image of a static fire test of a Teprel 1B engine. Source: PLD Space

Guidance, Navigation and Control (GNC) and avionics

The basis of PLD Space's defense of its Miura 5 in this regard, and they would be right, is the experience acquired in the flight of the Miura 1. As we discussed here previously, this was a success according to the established mission parameters. And despite various adversities, the rocket overcame them without any problem other than consuming more fuel than the RCS than expected.

However, there is a major drawback to this approach and that is that PLD Space did not develop, nor was it the development leader, of the Miura 1 avionics.

This role fell to GMV, this veteran company from Madrid was founded in 1984 and is one of the most prominent, if not the most prominent in the Spanish aerospace sector. Therefore, this part of avionics is understood to be It will be a more complicated development than the one that PLD Space has defended. In addition, there are doubts about the statements made by the Elche company regarding the possibility of converting the flight data from the Miura 1 to the Miura 5. Although it will be complex to carry out an adequate transfer of knowledge from Miura 1 to Miura 5”explains the hiring table in a more restrained way. Furthermore, later and speaking of human capital they expressly cite the loss of experience in the two fields discussed in this section.

It should be noted that several mentions of this agreement have been deleted from the Internet, hence the need to resort to a note in English that had not suffered this fate.

GMV PLD space agreement
Agreement announcing the collaboration between GMV and PLD Space in which it is reported that the Miura 1 and 5 (then called Arion 1 and 2) would carry GMV equipment. Source: GMV

In the CNG section, Raúl Torres has made contradictory statements regarding how Thrust Vector Control (TVC) will be carried out in the first stage. Therefore, it is impossible to conclude whether it will be carried out in two or three axes. Although the solution will be based on that of the Miura 1 and this time it does have a direct and simple application compared to its predecessor.

In principle, and based on the company's statements It will not have a reaction control system in the first stage. The best known as RCS, For their acronym in English, they are a series of “engines” based on cold gas. Here comes a boost since the Contracting Board positively values both solutions (TVC and RCS).

One of the systems that has been given prevalence when discussing the proposals is the flight termination system. In this case PLD Space has it automated. It is not directly descended from the Miura 1, since it did not have one as these are currently conceived, although they will probably have been able to draw some lessons.

Miura 1 versus 5
Miura 1 versus 5. Source: PLD Space

Structures and materials

A part that in recent years has become more relevant when discussing space launch systems are the materials used. The revolution that have meant the composite materials and printing 3D live with more classic materials as aluminum or steel. Behind coexistence lies a harsh reality: “the customer doesn't care if the rocket is made of carbon fiber, aluminum or plasticWhat he wants is for it to reach orbit” in the words of Raúl Torres. That does not prevent the company from leaving aside all the advances made in recent years in materials science. In fact, an element as critical as turbopumps will have a significant degree of manufacturing by 3D printing. Other sections, such as many structural supports, or the avionics boxes, will be manufactured with this new technique. Despite this, most of the rocket will be made of aluminum, perhaps alloyed with nickel, just like the Falcon 9.

Print Cells 1 The Portal
Image of three printers from the Relativity Space company in the process of manufacturing rocket stages. Source: Relativity

Human capital: the people behind the machine

An advantage of PLD Space such as its vertical integration is a weakness here. The Spanish aerospace sector is very compact and recruiting already qualified workers is complex. They have never had problems hiring qualified personnel, but they are mostly young, with little experience. Talent retention has been another relatively common problem in the company's long history., in thirteen years a lot has happened. In any case, they have already stated that they are in the midst of searching for employees and this is demonstrated by the multiple open positions that they have recently published in LinkedIn.

In addition to the problem of human capital, in general the Contracting Committee expressed doubts about the development organization chart. Raúl Torres is accused of having several positions considered contradictory. Among them, those of not having a quality department that would fall exclusively on him as CEO. It is also pointed out as a problem that the project director has him as head of the engineering department. And they close the paragraph attacking vertical integration with the following words: “The project organization chart is too vertical, practically everything depends on one person, which creates bottlenecks.”

Raul PLD senior executive
Image of the two "Raules", Raúl Torres (right) and Raúl Verdú (left) along with Ezequiel Sánchez (middle), the senior executive of PLD Space. Source: AstroAventura

Upper stage

This section includes a little bit of everything, propulsion, fine guidance, cowling, satellite dispensers and kick stage. Starting with the latter, although it was optional, the company chose to include one, although it is not clear that it will be developed in time or at all. To begin with, because the proposal only includes a very brief description. “The design seems very preliminary and without estimates of dimensions, mass or power,” the Contracting Board points out.

There is talk of two suppliers, presumably external, one Spanish and the other foreign, for the cap. Both options would make use of composite materials and although it is difficult to figure out the first option, the national one, the second international, it could be obvious. Ruag Space, currently Beyond Gravity is in charge, almost worldwide, of the manufacturing of caps. Many rockets, especially in Europe, use Swiss-made ones, including the Ariane 5 and 6, the Vega and the Atlas V. In addition, they were in charge of manufacturing the Miura 1 cowling.

There is a defined cap size in 5.5×2.3 meters.

Coif agreement with Ruag
Press release from October 2018 of the signing of the agreement between PLD Space with Beyond Gravity, then Ruag Space, for the manufacture of the covers of the then called Arion 1 and 2, currently Miura 1 and 5. Source: PLDSpace

Inside the cowling, work is advanced and the satellite dispenser and separator designs are well developed. And they have already made progress in how the different load configurations would be carried out, something important in a rocket as capable as the Miura 5. Both launches are contemplated ride share of multiple charges as well as with main charges that occupy a solo launch.

Test model of the Miura 5 cowl
Test model of the 80% scale cowl compared to the real one presented in the Antena 3 program "El Hormiguero". Source: Atresmedia

Recovery and reuse

Here the Miura 5 has a tremendous advantage, in the flight of the Miura 1 the aerothermal data strengthened the company's models. Although the change in the shape of the lower part, by using five engines in the rocket, will mean more than one headache in Elche. On the other hand, the recovery of the second stage is not contemplated either in the first instance or in the future.

There is no information about what technique will be used because it is under study. In 2021 the ESA granted them a contract worth 1 million euros to study which form of recovery was optimal. Three possibilities are studied in it:

  • Return trajectory to launch pad: similar to the one already used by SpaceX for a long time in its Falcon 9 and proposed for the Superheavy. Although with the variation that PLD would probably not return to the same drop zone, it would only get closer. In addition, they study the use of parachutes to save the fuel necessary for retro-powered landing.
  • Steep trajectory: In this trajectory the rocket would ascend much further vertically than physics recommends. This is done so that the first stage does not travel so far from the launch pad. It still requires braking in the upper layers of the atmosphere, and also increases the energy requirements of the second stage.
  • Propulsion braking and landing trajectory: the simplest in terms of CNG requirements. In this, the flight parabola is identical to that of a normal launch, but when the stages are separated, it would turn around to brake. But I wouldn't go around to the launch site like the first proposal. It would splash down, theoretically using a parachute.

The possibility of using parachutes could be doubted due to the increase in size of the Miura 5. But the company has confirmed that it is not a problem and that it is still possible. It is much better than the use of propulsive braking due to cost and especially the penalty to the load capacity of having to save fuel for landing. 

Ascent and recovery trajectories
Image from PLD Space that accompanied the press release to illustrate the different possible recovery trajectories that would be studied.

economic part

PLD Space has at least significant raised capital. It is estimated that at this time they have raised, between contracts, grants, and private financing rounds, more than 60 million euros. Despite the staggering figure, it is far from the 300 million which is estimated to require a rocket of the characteristics presented by the people of Elche. Furthermore, the proceeds must be discount the 29,7 millions invested or spent in the Miura 1.

Regarding the contract, they have justified a total of €41,967,000. It should be noted that 45 million was the total money set aside for the contract, but each company actually opted for 42, because the Phase 1 It contemplated up to three proposals. At this point, there is not a big difference between both companies, being a few thousand euros out of the total of 42 million.

Justified PLD budget for the Miura 5
Breakdown budget of the Miura 5

The Miura 5 is based on a base that is not as stable as the one that PLD Space has sold for the Miura 1. There are many open fronts, the same or worse for its competition, but it does not exempt the people of Elche from having to solve them. To do this they will not be alone and although less public than their competitors, they also have important and more established companies providing support. Their rocket is significantly larger than initially planned, which is also a problem. But, they finally present a proposal that reaches an astonishing load capacity, of one metric ton to low Earth orbit. With a target price of €10,000/kg of cargo, it would position it better than the Italian-French Vega, the great enemy of the new European private rockets.

Miura 5 promotional photo
Promotional photo of the takeoff of a Miura 5. Source: PLD Space

Contextualization

  • Due to the high competitiveness of the programs, much of the information is currently confidential. The compilation carried out uses information known during years of development and therefore could be outdated. If new information is received from the companies mentioned here, it will be corrected and published.
Martin Morala Andres