DailyDirt: Rocket Science Is Still Pretty Hard…

from the urls-we-dig-up dept

Rockets fail all the time. There are just a lot of things that can go wrong, and if everything doesn’t go right, the usual result is that the rocket and its payload self-destructs to prevent further damage (or just explodes all on its own). Fortunately, the hardware is getting cheaper with time, and more and more people are able to play with launch systems to get beyond Earth’s gravity well. Here are just a few more examples of rocket projects that are trying to do more with less.

After you’ve finished checking out those links, take a look at our Daily Deals for cool gadgets and other awesome stuff.

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Companies: kickstarter, moon express, nasa, rocket labs

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Comments on “DailyDirt: Rocket Science Is Still Pretty Hard…”

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Roger Strong (profile) says:

Re: Re:

That gun would replace a sounding rocket (a high arc briefly into space before coming back down), but not an orbital launcher.

And it would be very hard on the instruments. Many things sent up on sounding rockets tend to have sensitive optics.

Yes, Gerald Bull also ran Project HARP a couple decades earlier with the intention of eventually firing objects into orbit. But after the cannon fired the projectile, it required three rocket stages to reach and circularize orbit. Rocket stages along with the payload that would have to survive the gun blast.

It might make sense for launching water, fuel and dry goods. But given the tiny payload and the complication of having three rocket stages regardless, probably not.

Anonymous Coward says:

Re: Re: Re:

“it would be very hard on the instruments.”

– Compared to what?

The linear acceleration of subject “super gun” or other similar devices such as a rail gun, results in a significantly less severe vibration and shock environment compared to that found in other types of launch vehicle which use solid and or liquid fuel. SRBs are well known for their high vibration environment and the separation charges cause high shock, none of which are found in the hypothetical subject system.

Roger Strong (profile) says:

Re: Re: Re: Re:

Compared to a rocket.

Even SRBs are insignificant vibration/shock-wise compared to the shock from a “super gun” launch. The same goes for staging. And the rocket stages needed to reach orbit after the “super gun” launch may very well be solid rockets, in order to survive the gun blast.

Plus the SRBs used on most any orbital launch are used only in the first moments of launch, when there’s a whole lot of liquid fuel mass to dampen vibrations. (Yes, they forgot this with Ares I, but one stupid design doesn’t invalidate the large number of good ones.)

Anonymous Coward says:

Re: Re: Re:2 Re:

Not sure about your design specifications for this hypothetical gun, but anyone with a bit of knowledge in the field would opt for a linear acceleration profile when launching a satellite, orbital or otherwise. Linear acceleration is easily achieved by controlling the propellent burn rate.

Significant savings could be achieved simply due to the reduction in structural and testing requirements, the only problem being a change in requested orbit could require moving that huge barrel.

Roger Strong (profile) says:

Re: Re: Re:3 Re:

The original post was about a Gerald Bull style super gun, and that’s what I responded to.

A linear accelerator won’t produce a shock a bad as a super gun, since it can have a much longer barrel with acceleration along its entire length. But unless it’s many miles long, sea level to mountain top, there’s still going to be harder acceleration than a rocket.

And yes, it’s for one specific orbit. You can’t move your miles long linear accelerator, but you can point the last bit. That gives you a massive lurch to one side right at your highest speed. Since it’s in a different direction from the rest of your acceleration, greatly complicates how you design your satellite to handle launch stress.

Handle all that, and you’ve still only replaced the first stage of your rocket. You’re still on a ballistic trajectory. You still need rocket stages to reach/circularize orbit. If rocket vibration / staging shock is really all that bad, well, you STILL have to deal with it.

Most rocket alternatives – super guns, linear accelerators, balloon launch, towed launch – replace only the first stage at most. They save FUEL.

But rocket fuel is dirt cheap in comparison with the rest of your launch costs, way down in the noise at the bottom of the spreadsheet. Complicating your launch system is what costs money, and those first stage alternatives offer little payback for the added complication.

This is why everyone is looking at reusable first stages instead.

Roger Strong (profile) says:

Re: Re: Re:5 Re:

Single stage to orbit is not a fantasy.

Agreed. But “possible” is not the same as “practical.”

It’ll probably happen eventually for smallsats in low Earth orbit.

> Most sats have station keeping engines which can also be used for orbital maneuvers.

In a very limited way. Almost always in the same orbital plane. Staying in the same orbit – or moving to a new spot in geosynchronous orbit – takes an insignificant amount of fuel compared to launch.

There have been a couple satellites rescued after being placed in the wrong orbit. But we’re talking about them being placed at almost the right speed, in the correct orbital plane, but the third stage booster failed to circularize the orbit. After rescue with much of the station keeping fuel used up, the life of the satellite is greatly shortened.

Yes, you can build more fuel into your satellite design. But you’re merely incorporating the third stage of your launcher, not removing it from the design.

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