Cambridge N-Prize Team To Build Balloon-Assisted Rockets

Rob Goldsmith writes "Earlier this week we heard that Cambridge University Spaceflight would be entering the N-Prize competition. The N-Prize is a competition to stimulate innovation directed towards obtaining cheap access to space. Most importantly, the launch budget must be within £999.99. Cambridge University Spaceflight plan to win the prize using a balloon and a rocket. They have now opened up an official forum where the public can track their progress." The linked story has images from a test flight of July 23, and an interview with a member of the team, Ed Moore.

Inflation

What if someone did it for just under £999.99 but then the price of say rocket fuel goes up?

Re:Inflation

"Receipts must be produced, if requested, for all items or services purchased which fall within the ã999.99 budget"
http://www.n-prize.com/rules_in_full.html [n-prize.com]

So if you get a receipt from the fuel you used in the winning flight, it doesn't matter if the price goes up. If however you fail and you need to buy more fuel to try again, then the increase in price would be a problem to you.

Re:Inflation

What if someone did it for just under ã999.99 but then the price of say rocket fuel goes up?

The price of fuel hasn't really gone up very much, if at all. What's happened is that the money supply has increased, causing major inflation. The "War on Terror" in Afghanistan and Iraq and federal government bailouts of large banks were financed by "printing" (most of it is electronic actually) money from NOTHING and then spending it, which the Federal Reserve is more than capable of doing (so are other banks; see Fractional Reserve Banking [wikipedia.org]). When you keep doing that with hundreds of billions of dollars, it devalues the currency because there is X amount of wealth represented by Y amount of dollars in circulation. If Y increases while X does not increase or increases more slowly than Y, then each dollar is worth less than it was previously. Yes they are a cartel, yes they control the market by carefully adjusting how much oil they produce, but for the recent oil price hikes we keep hearing about in the media, OPEC is merely adjusting their prices to match the current value of the American dollar.

By the way, the Federal Reserve is a private corporation, which means that allowing them to print money and control our currency is UNCONSTITUTIONAL because only the federal government has this power. They are one part of a worldwide organization known as the World Bankers which controls the currency of almost every "industrialized nation" on the planet. Like most threats we face today, the founding fathers warned us about this one:

"I believe that banking institutions are more dangerous to our liberties than standing armies. If the American people ever allow private banks to control the issue of their currency, first by inflation, then by deflation, the banks and corporations that will grow up around [the banks] will deprive the people of all property until their children wake-up homeless on the continent their fathers conquered. The issuing power should be taken from the banks and restored to the people, to whom it properly belongs." -- Thomas Jefferson

"Deprive the people of all property". Sound familiar? How's that mortgage market doing these days?

Basically, if you can create economic crises and social unrest, if you can bankrupt a nation anytime you want, you can take over that country without having to fire a single shot.

Re:Inflation

To mod as Insightful the person who mentions "What if fuel prices increase?" while modding down as "Offtopic" the person who discusses why they have and might increase is contradictory, at best. They are either both offtopic or both insightful. I think sometimes moderators forget that "Offtopic" and "Troll" are not synonymous with "I disagree" and "I don't like what that guy said but I won't try to refute it".

Re:Inflation

To mod as Insightful the person who mentions "What if fuel prices increase?" while modding down as "Offtopic" the person who discusses why they have and might increase is contradictory, at best. They are either both offtopic or both insightful. I think sometimes moderators forget that "Offtopic" and "Troll" are not synonymous with "I disagree" and "I don't like what that guy said but I won't try to refute it".

This was a politely worded post. You worded this in a non-inflammatory manner and explained why you feel the way that you do, did not use invectives or name-calling and did not even take a very controversial position, and yet you were still modded as Troll. This is one of the better statements on the recent quality of Slashdot moderation that I've seen in a while. You point out that they were not applying the moderating guidelines and they respond by failing to apply them some more, without ever explaining why they disagree with you because they probably realize they would not have a leg to stand on. I'm fully expecting to get modded to -1 myself for pointing this out, but that's okay. I have karma to burn and I'll feel better for having done it since I believe this sort of bullshit needs to be called out wherever it occurs.

Re:Inflation

By the way, the Federal Reserve is a private corporation....

The Federal reserve is a government institution--your assertions to the contrary are false (and the "World Bankers" drivel is sheerest bullshit). (Cite [wikipedia.org])

What would anyone do with 10-20 grams in orbit?

I'm not really sure what the point of this is...what is anyone going to do with 10-20 grams in orbit? Can you even make a transmitter + power supply that small that would still be powerful enough to communicate with the ground? Or are you just supposed to send up 20 grams of foil or something that can be tracked with ground radar?

The X-prize was about getting people into space, which I think most people can see uses for (even if it was sub-orbital). I'm not really sure about this. Although I guess it's a great way to get a lot of free publicity, especially since the odds of anyone actually claiming the prize money are very low.

Re:What would anyone do with 10-20 grams in orbit?

I think the point, if there is one, is they wanted the rockets to have a payload and not just be a cylinder filled with rocket fuel. As for the size, I'm assuming its low to not only make it easier to achieve but to avoid people being accused of making missiles. Governments have a tendency to take notice when people build rockets large enough to carry explosives

Re:

Governments have a tendency to take notice when people build rockets large enough to carry explosives

It was apparently big enough to take pictures, and Governments notice that too. [slashdot.org]

Re:What would anyone do with 10-20 grams in orbit?

Can you even make a transmitter + power supply that small that would still be powerful enough to communicate with the ground?

When you have a 2+ meter dish with high-gain LNBF properly aimed, you can pick-up a radio signal from a wrist watch...

Or are you just supposed to send up 20 grams of foil or something that can be tracked with ground radar?

It wouldn't be a bad idea to send up something like a concave sheet of metal (aimed towards the planet) to use as a simple signal reflector. I'm sure hams and DXers would love the idea. It would be a lot easier and more consistent than bouncing signals off the moon.

It would be a very interesting world if we had a significant number of those in orbit. From the comfort of your living room, you could listen-in to any radio signals, being broadcast anywhere in the entire world, provided only that you have equipment that is sensitive enough to pick the weak incidentally reflected signal you want, out of the background noise.

Good luck

I'll admit, I don't know what the N-Prize is and I did not RTFA; I am assuming the goal is to reach some kind of sub-orbital or LEO flight. I've looked in to this for my own balloon projects. The energy savings from using a balloon are only a small percentage of the overall energy required to achieve orbit.

It takes about 20 times the amount of energy [wikipedia.org] to reach LEO than it does to just reach the same altitude. When you compare this energy requirement to the savings of launching from the ceiling height of a weather balloon [wikipedia.org] (40km) it is not much; especially considering you still have to get to the Karman Line [wikipedia.org] (100km) plus the weight of fuel required, which must then be lifted by even larger balloons. Therefore, it's more economical and efficient to burn the fuel as close to ground as possible [wikipedia.org].

I'm only an armchair rocket scientist though, so I might have this all wrong. In any case, I certainly wish them good luck - Maybe I'll go read the article now.

Re:Good luck

The idea behind balloon launched rockets has nothing to do with escape velocity/gravity. It has to do with aerodynamic drag. Aerodynamic drag plays a big role in eating up launch fuel at lower altitudes where the atmosphere is dense. A balloon launch bypasses that drag with a low cost, and disposable, balloon filled with hydrogen/helium without having to use expensive/heavy rocket fuel. The concept was developed and first implemented in 1949 and has been done a number of times since for high altitude experimentation and hobbiest projects. Wikipedia has a basic article inder the, somewhat archaic, name "rockoon" (mixture of rocket and balloon).

Re:

The idea behind balloon launched rockets has nothing to do with escape velocity/gravity. It has to do with aerodynamic drag. Aerodynamic drag plays a big role in eating up launch fuel at lower altitudes where the atmosphere is dense. A balloon launch bypasses that drag with a low cost, and disposable, balloon filled with hydrogen/helium without having to use expensive/heavy rocket fuel.

There's two problems with this scheme

1. The Hindenburg would just barely be able to lift John Glenn's Atlas booster.
2. A disposa

Re:

A disposable Hindenburg would cost tens of millions of dollars - while the few thousand gallons of fuel and oxidizer it replaced would cost a few thousand dollars.

Not necessarily. Being disposable, it wouldn't require much structure or external protection. It'll be destroyed long before damage can accumulate. It would mostly resemble weather balloons. The Hindenburg cost more, in part, because it was expected to see years in service.

Engine geometry and air pressure

You are correct in your energy estimates, but a high altitude balloon launch has other significant advantages:
1. Your rocket engine can be an engine with vacuum geometry meant to work well in space. This differs from an engine meant to operate at low altitude.
2. Your rocket design does not need to include complicated supersonic flight in dense air, so your vehicle can be more optimized for the mission at hand rather than aerodynamic.

Close to the ground for BIG rockets

The "burn most your fuel close to the ground" only applies to big rockets that are having to use early fuel to get later fuel up to altitude.

In the present case both those assumptions are violated, making their approach more sensible than it sounds. First off, for a big rocket most of the energy required will be used to 1) get up to speed and 2) gain altitude, with 1) being the biggest concern. For a small rocket, both of these will initially be swamped by 3) friction. The higher you are when you start, the less of your fuel you will waste just overcoming drag.

Secondly, the rule only applies when you are gaining the altitude by burning fuel in the first place. When you aren't having to burn fuel to get up there, you'd always come out ahead launching from a balloon (or even a mountain top) provided you could figure out how to make it work. Heck, with a tall enough tower (hint: think GEO) based on the equator, you could launch a satellite by hand!

--MarkusQ

Cost per kilogram

This wouldn't even make too much sense since
with that kind of money a kilogram in orbit would cost around 50000 pound. There are much cheaper means of getting to orbit:

http://www.futron.com/pdf/resource_center/white_papers/FutronLaunchCostWP.pdf [futron.com]

Interestingly small launchers seem to be less efficient than larger ones on average.

Maybe one should just try to hitch a ride.

On the other hand this seems to be a fun project.
I hope they are successful.

Re:

It seems to be an attempt to open up space launch capability to the little guy. Sure, when you look at the numbers, those big launch vehicles seem to be down-right cheap per lb., but good luck getting your 1lb. hobby project onto one of those launches. The organizations responsible for launching those rockets are, most likely, working exclusively with companies and fellow governments that need to launch 100lb+ payloads. Even if they'd work with an individual/small business, the red-tape and per-project o

Re:Cost per kilogram

Cost per kilo is somewhat missing the point.

Firstly, you can't buy a kilo to orbit. You simply can't.

You may be able to beg a ride-along if you have the right political connections, but otherwise it's impossible.

Secondly, it's unlikely that if 20g to orbit is $2000, 200g to orbit will be $20000.

Thirdly, and perhaps most importantly.

20g to orbit can't do much. You can put a bad camera, a radio, a solar panel, and a magnetometer on it, and maybe if you push the envelope really hard a 3-axis gyro. (to calculate your orbit)

200g however, even if it was $10000 per flight is in the realm where universities with modest physics, aerospace, or electronics facilities might consider it interesting to put up a small test sat.

Your cellphone weighs under 200g, even if it has GPS, GSM, accellerometers, wifi, camera, ...

With 200g in a small satellite, you've got a good shot at a reasonable camera, stabilisation using the earths magnetic field, GPS, a much better radio, solar panels, batteries to keep it alive during dark.

It's even reasonable that you could have a small part of it - say 50g - as a single-shot rocket able to optimise the trajectory.

I note that http://www.rcgroups.com/forums/showthread.php?t=814157 [rcgroups.com] there are amateur build fully remote controlled planes at under half a gram.

How about going the other way?

How about rocket-assisted balloons? That would probably be a lot of fun, too.

Re:

I, for one, welcome our new balloon rocket overlords.

Otherwise known as BOC and Cambridge Precision [ucam.org] .

I can see the usefulness of sponsorship by private enterprise, and it's reasonable to expect the sponsor to want their name on the craft, but this is ridiculous.

Re:How much does the balloon help?

I might have answered your question in another post [slashdot.org].

Re:How much does the balloon help?

I always thought that the way orbit worked was that you got far enough away that you could equalize the reduced pull of the earths gravity with your forward momentum to achieve a stable relationship.

Achieving orbit is not about how far away you are away, it's all about your angular velocity. You could theoretically achieve orbit at sea level, but atmospheric drag keeps that from happening on earth.
As satellite orbits the Earth, it is constantly accelerating, not because its speed is increasing, rather because it is constantly changing direction (speed + direction = velocity, change in velocity = acceleration).

The acceleration of gravity is 9.8m/s, so if you can achieve an acceleration of 9.8m/s in the opposite direction, you will be in constant free fall and establish an orbit.

It takes a lot of energy (32MJ/kg) to sustain this acceleration on Earth and maintain an orbit. However, you are correct that it takes less energy to enter into a geo-synchronous orbit than other types of orbits from different latitudes. Sorry I can't find a reference for it at the moment though.

Re:

"And here's the 2-2 pitch, oooh boy, Johnson's been decapitated by a fallen solar panel, drat the luck. Leiter steps in in relief. Brought to you in ultra-low def by Comcast."

Re:

But a cellphone cam might just work.

A cell phone CCD will be about 20 grams. But you also need the decoder, the DSP, and the transmitter, and the battery. If you still manage to do all that, then what's the use of a low-res image from 400 km? I understand that it might be cool once or twice, but that's what amateur satellites are for (this includes ham [amsat.org] and non-ham [stanford.edu] ones.) These satellites don't weigh 20 grams - they are larger, but they actually work.

Usually amateur satellites hitch a ride on some oth