A Rocket Built by Students Reaches Space | Hacker News Reader

A Rocket Built by Students Reaches Space

wired.com

191 pointscurtis66 comments

This is similar to a project I've been a part of called Operation Space, the difference being we are students not backed by one single university or organization. We've been monitoring USC's progress for months and they have been a great source of motivation, especially being that they held the previous altitude record at 144,000 ft.

We are actually launching out of the same site in New Mexico in about a week and looking to break the Karman Line and hopefully this new milestone. Link for anyone interested: https://operationspace.org/

Good luck! I'm envious and inspired :)

Good luck! How expensive would something like this be? Is it something I can casually do with my grown up kids on weekends?

Thank you! I don't have exact figures handy but short answer no, not at this scale at least. Manufacturing, design, materials, safety etc. all easily runs in the tens of thousands of dollars. We are on a much tighter budget, but AFAIK USC has spent hundreds of thousands of dollars on a single launch.

The article doesn't really say anything to the parent commenter's question...

This was not possible years ago (the part about students being able to do it, not nation states). What improvements in design and tech occured?

It has a lot to do with how much of a craftsman you are too. The really good people in the high power rocketry hobby can get above 100k feet on a budget of maybe $3-4k

These rockets are almost always 2 stage designs. The most expensive parts are the motors and electronics. Typically, you'll have redundant flight controllers for the booster and sustainer plus GPS/radio trackers to find them once the rocket eventually lands.

They aren't much different than the typical little hobby shop rockets just bigger and faster. The ones i've seen were maybe 8-10' tall, hand rolled carbon or fiberglass fuselages, and peak at around Mach 3.

https://youtu.be/sQw_C5KLhFM is fun to watch. There’s more info here https://ddeville.com/derek/Qu8k.html

I don’t think they spent too much money, but they had access to all the right tools as part of their day job.

Yes, in theory, if you happen to be an extremely talented rocket engine designer and architect and have about ~50-100 K lying around, you could in theory build a rocket that could cross the karman line. With modern technology, you could probably clone a V-2 if you were born a genius.

This is incorrect. The first student rocket to reach space was by the United States Air Force Academy

https://archive.is/20121212202343/http://www.af.mil/news/sto...

https://drive.google.com/file/d/0BwuvfKuNqZxQQ2xudkwtQXB4V0k...

From here:

https://twitter.com/skulumani/status/1131351960622391297?s=2...

The article seems to contradict it's own title:

> making the USC Rocket Lab only the second amateur group to ever send a rocket to space

I'd chalk it up to the ambiguity of natural language: "A Rocket Built by Students Reached Space for the First Time" as in the particular rocket referred to in the title reached space for the first time in that rocket's existence.

That's being too generous. Other than spacex, essentially every rocket that reaches space does so "for the first time". The title is intentionally misleading

I strongly disagree. The article describes in detail the student group's years of efforts to reach space, culminating in this success after years of failures. Moreover, they're the first collegiate team to make it to space (and the second "amateur" team).

The title is not intentionally misleading, just a bit ambiguous.

USC RPL was referring to CSXT, not the USAFA.

From the Drive link.

>(At the time of this writing the rocket and payload had not been recovered.)

Normally to claim these sorts of records recovery of the vehicle is required. USC RPL's Traveler III was "thought" to have reached space but they didn't turn the avionics on beforehand and therefore didn't verify or recover.

The article really should mention it. Seems to not do much justice not to.

They seem to refer to the CSXT rocket going even higher, but don't mention it by name.

In fairness I've been across these attempts for years. I was at BALLS when the initial Traveler CATOed, I watched it from Bruno's. Today is the first I've heard of this USAFA launch. The Wired article author is most likely much less across this stuff than I am. It could just be a case of USC RPL wasn't aware of the USAFA boosted dart flight.

And I still contend that recovery is necessary. USC RPL didn't claim Traveler III "broke the record" despite having good confidence it did given it didn't suffer a RUD during boost. They only "claimed" the record when they had a successful flight AND recovery. This is pretty much SOP for high altitude record attempts in the amateur rocketry community. I suspect it USAFA had recovered their boosted dart we would have most likely heard about it.

Thanks for sharing your experience here. I'd actually love to learn more about advances made in amateur rocketry lately, if you have any good links to share.

Currently there are three names that are repeatedly doing successful high alt two stage projects. Curt von Delius, Kip D, and Jim Jarvis.

Kip's two stage flight from last year. https://www.youtube.com/watch?v=rdkqZV4RirI

Kurt's PHNX4 flight https://www.youtube.com/watch?v=g0imcpdLdB8

And Jim, well just have a look for Jim Jarvis rocket on youtube!

Tripoli's records page is a good place to get more info on high alt record flights. http://tripoli-records.org/records/

And TRF is excessively noisy but it's the place where Jim and Kip document their work. Curt's a bit more secretive comparatively. https://www.rocketryforum.com/

The rocket reached 103.57km (100km is considered the edge of space) in altitude to spare anyone from reading this extremely annoying article. The solid fuel based rocket weighed 136kg and at just under 4m in height is impressively small for reaching this altitude. It’s parachutes deployed an it was recovered safely. There.

The article really is so annoying, and not just for that reason. There are no links or references to the technological advancements made here along the way. Another: they at least mention the CSXT team in passing (which the article seems to imply to an unwitting reader to not exist), but not even their name.

If I were king of a news outlet, I'd rather hire actual enthusiasts to write articles, and editors to touch them up, rather than have this kind of crap.

A wonderfull achievement, these students made.

The fact that it has taken the university _years_ to reach the goal combined with the solid fuel systems, which is less complex (but _not_ simple), shows the determination to have another group of non-pro's to reach that coveted altitude.

The article mixes all sorts of units but doesn't say exactly where the Kármán line is supposed to be in any single unit. The closest it gets is 50 miles plus 60,000 feet, which is a rather confusing way to say 98.75 kilometers.

The actual Kármán line is at 100 kilometers.

This rocket reached an altitude of 339,800 feet, or 103.57 kilometers. Its maximum speed of 3,386 mph (assuming "normal" miles, not nautical miles) is equivalent to 1.513 kilometers per second [fixed]. It's well below orbital velocity, but good enough for poking into space and coming back down.

There is quite a bit of debate around where the “Karman Line” should really be (the boundary to space).

Recently there have been efforts to define it as less stringent than the 100km limit: https://www.sciencedirect.com/science/article/pii/S009457651...

Potentially bringing it back down to 80km (the original definition was a range between 70-90km).

We can use Kerbal Space Program as base and set it to 70km

I know you're joking, but, KSP models a planet that's different from Earth in a number of ways. On Kerbin there is zero atmospheric drag past 70km; it's not the edge of space, it's the demarcation line at which indefinite stable orbits are possible. That is very different from Earth.

KSP is a whole different beast if you use the Real Solar System mod (which you should, once you learn the basics).

One of the differences of that mod is that it changes the 70k value to what it actually is in the real world, though.

> it changes the 70k value to what it actually is in the real world, though.

This surprised me. What is the real-world altitude at which there is zero atmospheric drag? I thought the atmosphere was basically just continuous.

Kerbin is designed as smaller than Earth and with a thinner atmosphere. The end result is that it's much easier to make a rocket there.

Kerbin has a soup-like lower atmosphere, and is much smaller, and much denser than the Earth.

Wikipedia [1] quotes from Kármán's autobiography where he discusses the origin of his idea, and he used an example of 300,000 ft. (91 km.) As the paper you link to shows, it is one of several candidates for the 'edge' of space, and they are all inherently vague. The paper shows how, by picking one reasonable set of parameters, you can put a Kármánesque line at 80 km., but its strongest argument for space beginning there is that several different candidates overlap at around that altitude.

[1] https://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line

Maybe space should be defined as the altitude you need to have to not have your orbit decay in less than one orbit. I wonder what altitude that is, actually.

The paper linked to by aerophilic goes into that issue in some detail, but it does not lead to a sharp distinction, either - for one thing, the ballistic coefficient ranges over a couple of orders of magnitude, with smaller objects coming down sooner.

If we confine the discussion to circular orbits, it suggests that 100km is a better number than anything lower, but elliptic orbits can get away with lower perigees, which is a concern when the boundary of space is being defined for national territory purposes (e.g. spy satellites with a perigee over the nation being spied on.)

There's a guy in the high power rocketry hobby that is aiming for space this August at the BALLS event in Nevada. He won't say it, but given what he's done in the past, and the pictures of what he's building there's no other reasonable explanation.

A guy last year hit 244k feet ( 2/3 the way to the Karman line) on OTC solid rocket motors available to NAR or Tripoli L3 certified amateurs. Granted, it was a very exceptional rocket, but access to space by amateurs is getting closer every day.

That rocket https://mach5lowdown.com/2018/11/07/phx4-rocket-launch-to-20...

BALLS http://www.tripoli.org/Balls

I have no experience in rocket science, but can anyone here explain why it's so difficult to reach the Kármán line?

What else besides power/weight ratio is required to achieve something like this?

> For most of the history of spaceflight, sending a rocket to space required mobilizing resources on a national scale.

From the article. It's not that it is super hard to do nowadays if you have a near endless supply of resources and money, but for students in a science project it is a big deal.

If you accept premise of unlimited budget and outsourcing, sending something to space is about as difficult as saying “Hey Elon, I want this thing to go to space.”

The point here is that college students are able to pull this off with a small budget and lots of DIY.

Assuming ample money, resources, and support, height isn't a big deal (for solid state rockets).

From my experience as a part of a collegiate (liquid) rocket club, just getting to manufacturing is a major hurdle.

There's legal red tape, university specific red tape, insurance/liability, material sourcing, funding, manufacturing, testing etc.

Note that some of these steps may require specialized facilities/equipment, transport, etc. Outsourcing (e.g. manufacturing) trades off for added red tape. ITAR is fun.

This makes working towards great heights a slow process, and if something goes wrong during testing/launch it's a major set back.

Rocketry is just plain difficult and expensive.

Consider the "Tyranny of Rockets" problem: if you want to send a rocket up 1 km, you need X fuel. But to get to 2 km, you need way more than 2X fuel- because you first have to carry all that extra fuel up 1 km, which takes more energy/fuel, before you can use it to go the other km. And if you want 3 km up... well, you get the idea. It's exponential in cost.

Then the problem of the fuel itself. It has to be something super-energy-dense: lots of energy (velocity) for the least mass. The most super energy dense substances are usually used to make bombs, so basically you're building a metal tube with explosives inside and hoping that you can direct the explosion correctly such that your rocket goes up.

And then you have to make sure your payload- in this case some sensors to prove you actually went up that high- have to be lifted (mass) and not break. In the case of this team, their previous rocket probably did reach space but the sensors weren't working so they have no evidence!

If you want to really learn this stuff, play the game "Kerbal Space Program". It's not accurate in any sense, but it gives you the instincts of why and how rocketry and orbital mechanics work.

>The most super energy dense substances are usually used to make bombs,

By volume or per mass high explosives usually don't have much energy density compared to things like liquid fuels (ie, gasoline) or even solid fuels. This holds true for all high explosives (substances used to make bombs). They're all pretty low energy density. They're just high power because of the low time to release the energy.

>Consider the "Tyranny of Rockets" problem: if you want to send a rocket up 1 km, you need X fuel. But to get to 2 km, you need way more than 2X fuel- because you first have to carry all that extra fuel up 1 km, which takes more energy/fuel, before you can use it to go the other km. And if you want 3 km up... well, you get the idea. It's exponential in cost.

Is this correct? I know how the Tyranny of the Rocket Equation relates to mass, but I've never heard it used in terms of altitude before. Using the kinematic equations, it seems the initial velocity required to reach height 2X would actually be less than double of that for just X. However, I'm not sure if that also applies to rocket launches and if it does how it relates to fuel requirements.

Feel free to correct me if I'm on the completely wrong track here.

It's not correct. The rocket equation is exponential for delta-v, not for altitude. Getting to 2km could easily be free once you've hit 1km, if your rocket is traveling fast enough at 1km when it cuts out to coast much higher.

It's getting to, say, 2 km/s that takes more than double the fuel of getting to 1 km/s. It's not a simple relationship though (like say the inverse-square law); it's related to propellant velocity, which for chemical rockets is in the neighborhood of 4 km/s. Reaching velocities greater than your propellant velocity is where the exponential ramp really starts to take off.

And no, it's not just mass either. If you have a rocket that sends mass M to velocity V, then double the size of the rocket and it'll send mass 2M to velocity V. The rocket equation tells you the ratio of fuel mass to payload mass required to reach any given delta-v. That's what grows exponentially as the desired delta-v grows.

That's not at all true, the tsiolkovsky rocket equation relates to delta-v (change in speed) and mass fraction, NOT altitude.

Delta-v is not change in speed here:

Delta-v, as used in spacecraft flight dynamics is a measure of the impulse that is needed to perform a maneuver such as launch from, or landing on a planet or moon, or in-space orbital maneuver. It is a scalar that has the units of speed. >>As used in this context, it is not the same as the physical change in velocity of the vehicle<<.[1]

[1]: https://en.wikipedia.org/wiki/Delta-v

To clarify: is the distinction between delta-v and change in re velocity that thrust could be applied in any direction, including in the braking direction, so a rocket applying a maneuver of given delta-v could end up with an increased or decreased (or zero) final speed?

If the above distinction is correct, then in general delta-v is not coupled to the physical change in the rocket's velocity. But in the case of a conventional rocket with a fixed thrust vector launching from Earth's surface (as in OP's comment), isn't it perfectly true that delta-v is equivalent to change in velocity (barring air resistance)?

It's also that you can go "backwards", e.g. slow down to land on another planet.

Yes, you're right, I was talking about the restricted case of straight up as the Karman line would likely be.

It's not exponential in cost. It's just not linear in cost. It must be polynomial then.

Added complexity likely provides a nice bump.

By and large, as long as you're using decent specific impulse propellants, the hard part is not really the rocket equation but rather that rockets are extremely complicated sustained explosions. Oh, and they're really expensive. You have to worry about pogo, combustion instability, etc.

i've been in the high power rocketry hobby for a year or so.

Mostly it's getting everything to go right a the same time. Fin flutter destroys rockets, so does wind sheer, so does bad flight controllers or bad programming. Parachutes not deploying properly in low pressure high altitude flights, second stage igniters not working as fast as they should at low pressure, the list goes on and on.

I've been wanting to get into this for a while now. Do you have any groups you'd recommend? Solo study has its limits. :)

The below forum is pretty much ground zero for the hobby in the United States IMO. There's some very very talented regulars there who are truly pushing the limits. All the owners of the electronics and software used in the hobby are on this forum too and post regularly. Many University teams show up on this forum too, i believe this USC team is there from time to time asking for advice.

https://www.rocketryforum.com/

this thread in particular is fascinating, a build thread for a 2 stage rocket that eventually hit about 150k feet

https://www.rocketryforum.com/threads/workbench-2-0-two-stag...

Here's a post with some nice pictures of the rocket, launch, and apogee

https://www.rocketryforum.com/threads/workbench-2-0-two-stag...

Surprised to see the photo of the rocket back on the ground, with the nose cone still attached by some sort of rope.

It would appear that the biggest difference between this thing and an Estes rocket is the size?

From a simplistic standpoint, the only difference between the Space Shuttle solid rocket boosters and an Estes rocket was the size.

In reality, a solid rocket motor at this scale is very difficult to manufacture reliably, and with the thrust profile that will provide the performance that you need to reach your goals.

That's not to mention the avionics in this rocket, the materials (carbon fiber laid down by the students), the deployment systems for the nose cone, and the manufacturing of the nozzle engineered to provide adequate thrust through the entire range of atmospheric pressures.

To be fair, though, all of these are solved problems that are easily overcome with budget and outsourcing. Ex. you can buy quality carbon fiber tubes in whatever diameter and thickness you want from multiple suppliers, contract out the nozzle based on existing designs to a CNC milling or titanium SLS printing company, purchase aerospace-rated avionics packages, etc. The impressive part here is that the students seem to be doing a good chunk of these things mostly in-house and with less money than it would normally take.

Sure you can contract out the work, but paying for someone else to make a rocket you launch doesn't really qualify you to say that you did anything. It also doesn't teach you anything, so what's the point?

Most of what you work on in college is solved problems, because college is about learning and not about original research.

Space shuttle is rocket with wings and additional 2 million parts.

At a very high level, yeah, most every rocket is just a tube that's pointy on one and and goes fwoom at the other. But this seems like it might be more similar to an Estes rocket than just that. The space shuttle's solid rocket boosters don't deploy the parachute by ejecting the whole nose cone, which is attached by a shock cord, and letting it drag the parachute out of the rocket's body.

That's really what I was reacting to. That, not only did they get to space, but they apparently got to space using a much more rough-and-ready design than I would have expected. The hacker in me loves that.

Bigger also means they can put more sensors onboard (though you can do quite a bit with Estes). But even the Shuttle SRBs used parachute recovery, although without popping the nose cone.

Biggest difference I can think of is that the SRBs had a gimballing nozzle. From photos on the project website, it looks like fins are fixed too. I don't know the law around it, but guess adding control surfaces would make this into a guided missile!

https://www.uscrpl.com/traveler-iv http://www.uscrpl.com/updates/2019/5/22/traveler-iv

I've done a small amount of model rocketry. My interest in the hobby basically ended once the various old-timers I had access to convinced me that any sort of guidance beyond extremely basic horizon tracking would indeed amount to ITAR controlled missile tech.

My interest ended when I couldn't afford to build the model rocket kits I wanted to build (I was a kid with a very limited budget). When I got older and had money, the lack of any convenient launch sites probably discouraged me from getting back into it.

you're pretty much right on. There's not a whole lot of difference. Where it gets hard is holding it together past Mach 1 and building it in the first place. Misaligning a fin on an estes rocket is no big deal, misaligning a fin on this one would mean near-instant destruction. Also, materials, cardboard isn't going to cut it. At this scale the best option is hand rolled carbon fibre which is an art in its own right.

So that's where that crazy tuition goes....

Also, wonder why not https://en.wikipedia.org/wiki/Aerospike_engine ?

Is there such thing as a solid fuel aerospike?

I'd think the spike geometry would still give ambient (maximally efficient) expansion over a range of altitudes but IDK how they'd make that work with solid propellants.

I'm sure the students didn't because it's never been done before, and you get an A for succeeding with proven technologies, not failing with unproven ones.

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