We are Back!

     After a long time without publish here, it is time to come back.
    There is lot of ideas to share and some to build for sure. The L10K rocket engine was improved during this time, resulting in a more efficient and "cheap" way to create a Amateur LRE. Of course this will not be a state of art engine, since most of solutions are chosen to be realistic in a amateur environment.

     Probably the most difficult component to develop may be the Turbopump system. The complexity of a high rotation speed device, working between 90K and 900K with a large amount of smaller components, probably will be the most challenging task.
    In the image below, there is an old version of L10K Turbopump. It is a first view of this component based in a simplification to be able to change pumps without much problem. The first approach shows that the oxidizer and fuel pumps will require 13kW and 14kW respectively. This power range is also possible by driving pumps separately by an electric motor in a test stand (the idea has been used by RocketLab in its LOx/RP1 Rutherford engine. The full test is available here).

L10K Turbopump.

     During next posts, more details about this and others component will be described here.

VLFS for N-Prize

     We finally have a first drawing of our rocket for N-Prize Race. Its preliminary design is just to help us to improve its aerodinamics.
     Together with VLNS, we are calculating a better trajectory for VLFS (Fempto-Sattelite Rocket Launcher in Portuguese). But, due to some N-prize rules, we must to reduce costs. So, we are planning a ballistic trajectory with minimum control system.
      This procedure implies in a low precision satellization but allow to keep launch cost below £999,99. Even with this simplification, our calculation show launcher capable to put about 50g in a 800km (SMA) orbit. Therefore, will be necessary to put about 35g of weight in upper stage to achive request orbit with a 15g satellite.
     But, for us, the biggest challenge is to keep sattelite mass between limits. Unfortunatelly our recent design (transmissor only) was weighting above 40g. Send at least 9 orbit comprovation at about 800km will be our biggest achievement.

      Soon as possible, we will show some drawings and static tests.

N-Prize

     After a few weeks without posts, we're back. And with a great news. Our group is participating on N-Prize competition.

     We still working in our VLNS, but in break times we're projecting a very small and cheap rocket to reach Earth orbit with no more than £999,99.

     We're making a few simulations to decide stage mass, ignition point and orbit insertion, to low cost and achieve desired performance.

     We will launch this rocket (VLFS or Fempto-Satellite Launch Vehicle, in portuguese) on ground and in a launch rail (just like sounding rocket). I'ts preliminary design is showing about  327kg loaded and divided in 5 Stages. We still need to optimize its 1st and 2nd stage. 3rd, 4th and 5th stage will be tested soon.

     While that, our main project (VLNS) is growing. Now we're working in a control system plataform to improve its confiability.

     This year we hope to test a few components.

Centrifugal Injector

A few weeks ago, we just build a small element of injector. We made some tests to determinate its mass flow rate in function of pressure drop (this graph gave us injector's Discharge Coefficient Cd).

One of big advantages of centrifugal Injector is its mixture efficience in comparison of impinging jet.

Due to its complexity, centrifugal injector are not so common for amateur. But we are trying to overcome the difficulties of developing. Our first injector had 1,6mm of tangential holes, with a total of 6 holes distributed around vortex chamber (separated to 60 degrees).

But today we just finish our second centrifugal injector. It have six 0,8mm tangential holes around vortex chamber.

Our first injector have a 60g/s mass flow rate at pressure drop of 2 atm. We are developing now a device to measure this parameter and its mass flow distribution in radial and axial direction.

We will test this new injector along this week and soon as possible we will test this new injector an compare both with its respective calculations.

Below is the video of our first injector test (without much criterion yet).

Nano-Satellite Launch Vehicle (VLNS) Part-001

After a long time without a post, we're back.

Well, this is our first post in english. We hope to post in russian and portuguese too at the same time in the future.

Actually we are finishing a heat transfer calculation of L10K and its version to vacuum. In parallel, we're running some simulations that we hope to publish as soon as possible.

While that, we're working in 3D integration of components of VLNS (Nano-Satellite Launch Vehicle). Below is a image of how it's right now. There lot of work to do, but it's taking shape.

We will post our progress in calculations and simulations in this weekend.

Algumas Modificações

Adotando uma nova configuração objetivando desempenho, baixo custo e (segurança), o L10K foi reprojetado tendo seu oxidante substituído por LOx (Oxigênio Líquido). Com isso, todo o veículo lançador de Nano Satélites foi reprojetado e, com o auxilio do software recentemente desenvolvido pelo grupo, sua carga útil foi aumentada para um limite de 18kg em orbita baixa (300km).

Focando neste novo design, está sendo feita uma simulação em CFD do motor em diversas configurações. A primeira simulação foi do motor operando em regime nominal ao nível do mar. os resultados de fluxo mássico convergiram para os parâmetros previamente calculados no projeto do motor. Atualmente está sendo realizado um cálculo do mesmo motor, porém em funcionamento em ambiente condizente com uma altitude de 10km. Futuramente o cálculo será refeito com pressão ambiente condizente com 30km e 70km (praticamente vácuo). A segunda fase de cálculo irá reproduzir as mesmas condições ambientes para um cluster de 4 motores funcionando simultaneamente.

O objetivo destas simulações é projetar uma seção dos motores de forma que a pluma resultante da combustão não afete estruturalmente o veículo e nem afete o desempenho dos motores em regime nominal de funcionamento.

Software para Cálculo de Trajetórias Balísticas - 2

Depois de algum tempo analisando o código utilizado para o software de calculo de trajetórias, resolvi corrigir um pequeno erro que diminuía a precisão do mesmo e aproveitei para adicionar parâmetros para trajetórias orbitais.

Entretanto foi necessário adicionar uma condição de contorno para o cálculo, pois mesmo ao calcular o fim de queima do último estágio, entrava em um loop infinito.

Corrigido os problemas e aprimorando a precisão, foi feita várias comparações utilizando dados de foguetes já bem conceituados no quesito de satelização e os valores obtidos foram muito satisfatórios.

Aproveitando o software finalizado, foi recalculado e optimizado o VLNS. Uma opção muito interessante (que será melhor comentado futuramente) foi a substituição do HTP (Peróxido de Hidrogênio com concentração acima de 85%) por Oxigênio Líquido. Com isso, será possível proceder com a satelização de 18kg em orbita baixa utilizando apenas dois estágios. Entretanto este será tema para uma futura postagem.