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Neil1993

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Posts posted by Neil1993

    Rocket vs Re-entry Capsule Aerodynamics

    in Science & Spaceflight

    Posted · Edited by Neil1993

    I don't know too much about re-entery, but I might be able to help with rocket ascent. A flying body has two centers that you need to consider; the cente of mass and the center of pressure. You already know what the center of mass is. The center pf pressure can be considered as the point where the total sum of a pressure field acts on a body.

    In a rocket exhibiting positive stability (this is what you want) the center of gravity will be closer to the nose than the center of pressure. Why is this so? when a rocket is perturbed and at a non-zero angle of attack (the airstream isn't parallel to the longitudinal axis of the body) the body generates lift, as anything at a non-zero angle of attack would. This lift, which acts at the center of pressure, restores the rocket to a zero angle of attack. Here's a picture to make this more clear:

    rktstab.gif

    Side note: you can have unstable rockets that still fly. They just require a ridiculous amount of computer control to keep going straight.

    Could we actually build an interstellar probe ?

    in Science & Spaceflight

    Posted

    Personally, I think it would be best if we humans held off on interstellar probes for now. The previous users got it right. By the time a probe with our current technology reaches another star, we may already have the technology to travel there in the blink of an eye (Maximum Warp, Engage!). I think it would be better if we only travelled within the abilities of our current propulsion systems. That's not to say that we should confine ourselves. We should still be tirelessly researching and innovating so as to get the best possible propulsion system for interstellar travel.

    3D printing spider robot in space

    in Science & Spaceflight

    Posted

    Imagine this: Lifting naked engines, fuel tanks, crew quarters etc. and dumping them in a clump in parking orbit. Then astronauts will come, connect everything together and go back to Earth. Then along comes the SpiderBot, and starts weaving its net around internal components of a spaceship, creating any structural support the vessel will need (which shouldn't be much - it's already in microgravity, and doesn't need to withstand any serious acceleration). There is no need to send heavy structural elements to space - couple of tanks of whatever raw compound bot will use will be sufficient.

    Sounds like the future of human space exploration. As someone who has worked with 3D printing, I can say that the technology holds great promise and it's use it space is almost a must.

    Giant Geysers On Europa; Planetary Society Wants Robotic Mission ASAP

    in Science & Spaceflight

    Posted

    if they want it so badly, I'm sure they are committed enough to donate the money to make it happen out of their own pockets, rather than have the taxpayer bleed for their hobby.

    A mission like this is hardly a hobby. Finding life, or the beginnings of life, on another planet/moon would prove that life is not simply a one-time fluke that ocurred only on earth. As well, the knowledge gained by studying extraterrestrial life would help us better understand how life evolved on earth and it would help us to find life elsewhere in the universe.

    Crowd-Funded, Water-Propelled Satellites?

    in Science & Spaceflight

    Posted · Edited by Neil1993

    The big question IMHO is, how big the ISp of such an engine is (compared to "normal" ion thrusters, but also in numbers)

    I found a lot of information here:

    http://pepl.engin.umich.edu/thrusters/CAT.html

    However, they do not provide an Isp. They do say that it can produce 2 mN of thrust on 10 W of power. They also had details, such as the fact that the operational life exceeded 20,000 hours, the amount of fuel was less than 2.5 Kg and the exhaust velocity was 20,000 m/s. From this, I calculated an Isp of around 5800 s. While this is considerably lower that other thrusters, the upside is that this type of engine is relatively light and it provides relatively high thrust for how little power it consumes. For instance, the NEXT system requires 7.7 kW for a maximum of 236 mN of thrust while this engine only requires 100 W for 200 mN of thrust.

    Crowd-Funded, Water-Propelled Satellites?

    in Science & Spaceflight

    Posted

    Recently, a friend of mine showed me a kickstarter for a new kind of satellite project. This one proposes launching a small cubesat with a water-propelled electric motor.

    Their goal is to use this new kind of propulsion to put small, student-built satellites into deep space.

    Should this technology prove feasible, it would make many space based applications much cheaper, such as meteorology, mapping, space weather monitoring and asteroid inspection, to name a few.

    they have, at this time, met their funding goal, but there are still a few days left.

    here's the link:

    http://www.kickstarter.com/projects/longmier/cat-launch-a-water-propelled-satellite-into-deep-s?ref=search

    China aims for the Moon - article in "Nature"

    in Science & Spaceflight

    Posted

    That's very true (both previous posts). However, it would still be nice to have governments more focused on long term strategies. I know that in Canada most politicians never seem to see any further than the next election, while space related to projects can stretch from a decade long, like to Apollo moon landing (ok, that was 7 years) to a century (the 100 year starship). It's unlikely that we'll get many big groundbreaking and frontier pushing projects with that mentality. :P

    China aims for the Moon - article in "Nature"

    in Science & Spaceflight

    Posted

    The post about how the non-democratic nature of China's government is particularily interesting. It is true, that in the democratic systems in north america (I'm living in Canada right now) politicians will avoid long term projects or strategies, often for the petty reason that the next guy will get to take credit for it. How could we possibly change our own democratic systems to encourage long term strategies and yet still maintain the democratic ideals?

    3 non-rocket scientists attempt to put a rocket into space

    in Science & Spaceflight

    Posted

    I found that video thoroughly entertaining. I am, in fact, involved in a competition where the main goal is to launch a large rocket to 10,000 feet with a scientific payload (an anti-matter detector, in my team's case).

    I do wonder, though, what kind of simulation and analysis they did before launch. On my team, we need to perform CFD analysis, thermal analysis, vibration analysis, structural FEA and at least 3-DOF trajectory analysis before we can start manufacturing. Also, why didn't they use all composite design? It would have been far more efficient in terms of weight.

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