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/
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?
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.
I don’t think they spent too much money, but they had access to all the right tools as part of their day job.
> making the USC Rocket Lab only the second amateur group to ever send a rocket to space
The title is not intentionally misleading, just a bit ambiguous.
>(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.
They seem to refer to the CSXT rocket going even higher, but don't mention it by name.
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.
Kip's two stage flight from last year.
Kurt's PHNX4 flight
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.
And TRF is excessively noisy but it's the place where Jim and Kip document their work. Curt's a bit more secretive comparatively.
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.
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 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.
Recently there have been efforts to define it as less stringent than the 100km limit:
Potentially bringing it back down to 80km (the original definition was a range between 70-90km).
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.)
This surprised me. What is the real-world altitude at which there is zero atmospheric drag? I thought the atmosphere was basically just continuous.
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.
What else besides power/weight ratio is required to achieve something like this?
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.
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.
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<<.
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)?
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 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.
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.
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.
The point here is that college students are able to pull this off with a small budget and lots of DIY.
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.
this thread in particular is fascinating, a build thread for a 2 stage rocket that eventually hit about 150k feet
Here's a post with some nice pictures of the rocket, launch, and apogee
It would appear that the biggest difference between this thing and an Estes rocket is 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.
Most of what you work on in college is solved problems, because college is about learning and not about original research.
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.
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!
Also, wonder why not https://en.wikipedia.org/wiki/Aerospike_engine ?
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.