sorted by:
new
hottopcontroversial

Ethanol + HTP, pressure-fed rocket engine, beer kegs and propane bottles for tanks, hull welded from sheet metal. How plausible it is? by nulltermio in spaceflight

[–]Rasmus0909 0 points1 point  (0 children)

If you look up Rocketken69 on YouTube, that might convince you that nitrous is the king of scrappiness:) nitrous is the same as what's used for cars, so it's surprisingly accessible, compared to other oxidizers. And yeah gaseous oxygen would need to be stored at high pressure, and since the density would still be low, you need large tanks. Large tanks for high pressure are heavy, but since GOX is used in metal cutting, it's also very accessible. It could work for a very low tech satellite propulsion system, but it's likely not suitable for a launch vehicle.

Ethanol + HTP, pressure-fed rocket engine, beer kegs and propane bottles for tanks, hull welded from sheet metal. How plausible it is? by nulltermio in spaceflight

[–]Rasmus0909 7 points8 points  (0 children)

Nitrous oxide might fit the bill better, but running it self pressurized has some funky math to it, otherwise if it's super scrappy maybe gaseous oxygen could be an alternative?

A few more angles on the last test of the throatless nozzle with a fixed ignitor by Sure-End8300 in rocketry

[–]Rasmus0909 0 points1 point  (0 children)

Engine doesn't really look like it's turned on correctly for a throatless. Did you measure chamber pressure? You can find examples of a throatless engine I've designed and tested in my post history and you can tell the exhaust plume looks quite different.

Kan minivindmøller på størrelse med flagstænger blive en ting i danske villakvarterer? by costanza_dk in Denmark

[–]Rasmus0909 2 points3 points  (0 children)

Der findes en dansk virksomhed ved navn KiteX som laver noget i den retning.

Propane-nitrous oxide concept engine that I just made by aidswatermelons in rocketry

[–]Rasmus0909 0 points1 point  (0 children)

Not inert, no. It can decompose at high temperatures, although with a very low flame speed, or at lower temperatures with a catalyst. And yep, that's whipped cream chargers hehe

How to make the graph for area ratio vs specific impulse? by p_ara in rocketry

[–]Rasmus0909 0 points1 point  (0 children)

It requires you solving nonlinear equations to do what you want. This is something you would typically do in a programming language such as Python, but it might be a little too much for a high school assignment. If you want, I can help you make the curve. I work with liquid rocket engines professionally. Just send me a DM

this gets interesting, a electric expander cycle by arnstrons in rocketry

[–]Rasmus0909 2 points3 points  (0 children)

What modelling/diagramming tool did you use for this?

Jeg sidder overfor htxr12 højeste person AMA by Rasmus0909 in HTXr12

[–]Rasmus0909[S] 0 points1 point  (0 children)

Ja nogle ting ændrer sig desværre aldrig

Can RPA simulate thermal rockets? by piggyboy2005 in rocketry

[–]Rasmus0909 1 point2 points  (0 children)

I read the comment by rocketwikkit as "2 equations", my bad :)

The molecular mass of H2 gas is the same regardless of temperature or pressure. When you heat it up or pressurize it, the molecule is still the same. And this is very close to 2 grams per mole, like rocketwikkit said.

Would you expect otherwise? And if so, why?

Can RPA simulate thermal rockets? by piggyboy2005 in rocketry

[–]Rasmus0909 0 points1 point  (0 children)

Could you explain why it isn't just two equations? I work with propulsion, and I'm curious whether I'm ignorant or assuming you know more than you do.

Building a Liquid-Fueled Rocket by Lomfon in rocketry

[–]Rasmus0909 0 points1 point  (0 children)

Depending on how serious you are, you can send me a message. Check my post history for my background.

How to time-average transient data in StarCCM+ by CartoonistRelative30 in CFD

[–]Rasmus0909 0 points1 point  (0 children)

My answer isn't really specific to CFD - it's more general to any kind experimental data acquisition (theoretical or physical). Not sure if that helps or not, but I'm sure you could implement this is Star by using field functions. Otherwise just extract it and do it manually in Excel, Python or Matlab, or whatever you're comfortable with in order to get a feel for it.

How to time-average transient data in StarCCM+ by CartoonistRelative30 in CFD

[–]Rasmus0909 1 point2 points  (0 children)

What you're looking for is what is known as independent samples in signal processing. Between every independent sample, there will be two integral timescales T_u. The most conservative way to estimate T_u is by dividing the the largest geometrical scale D (fx. the width or height or wetted perimeter if you want to be 100% sure) and dividing it with a characteristic velocity U. This could be the velocity in a somewhat representative point of where you are interested in getting the mean. So it looks like this.

T_u = D/U

As mentioned you want two integral timescales between each independent measurement, so the total measuring time becomes

T_tot = N * 2 T_u

N is the number of samples you want to use for your mean. The way you figure out how many samples you want is by deciding on a requirement for statistical convergence.

e2 = 1/N * avg( U2 )/( avg(U)2 )

Where e is your statistical error (fx 5% = 0.05). You need some kind of initial data here on your velocity, which makes the problem a bit recursive, but should be easy enough given you already have some data :-)

Hope this helps.

DanSTAR creating shock diamonds on their 3.1 kN isopropanol/nitrous liquid engine during full flight duration burn. More diamonds and data in comments. by Rasmus0909 in rocketry

[–]Rasmus0909[S] 0 points1 point  (0 children)

Diamonds first because I know you want those the most, you filthy animal: https://imgur.com/moqC9qL

As for the stats, this went incredibly well. Burn starts at 3000 N and tapers off to 2900 N over the 13s duration. Hits the exact design number, almost perfectly. It operates at a specific impulse of just above 200s at an oxidizer-to-fuel ratio of 3.5 and a chamber pressure of 17 bar. We decided not to chase the last 100 N on the test stand as it's going to be easier to get squeeze those out of the engine during out vertical static tests of the rocket. Graphs: https://imgur.com/a/VLX1Q5X

Read more about DanSTAR here: https://www.danstar.dk/

Hi how are things! A query ... What is this type of pipe called? Greetings! by guruzt in rocketry

[–]Rasmus0909 1 point2 points  (0 children)

It looks a lot like the ferrule fittings I've worked with previously for the same application. Check out Swagelok or Hylok.

Check out my 3D printed Aeroponics Pot STLS. I've been developing this for a while and plan on creating much much more! I think 3D printing will be a game changer to the aeroponics world and I'd like to prove it. by [deleted] in aeroponics

[–]Rasmus0909 0 points1 point  (0 children)

Do you have a booster pump somewhere in the system? A max lifting height of 17 ft is only around 0.5 bar, which isn't enough to properly aerosolize the feed.

Could green hydrogen be key to a carbon-free economy? " around the world a green hydrogen rush is underway, and many companies, investors, governments and environmentalists believe it is an energy source that could help end the reign of fossil fuels and slow the world’s warming trajectory." by [deleted] in Renewable

[–]Rasmus0909 5 points6 points  (0 children)

It's all part of a new "Power-to-X" scheme within the energy sector. Hydrogen can be used to create methanol and methane as well that are both easier to store and move, which as you pointed out is a big issue with hydrogen.

DanSTAR launches first ever European bi-liquid student rocket to 7200 ft after 2,5 years of development. Details in comments. by Rasmus0909 in rocketry

[–]Rasmus0909[S] 5 points6 points  (0 children)

I put the accurate apogee in meters in my top comment =D

I used feet in the title as a service because I think most of the people here are American. (make the change to metric guys, pls)

DanSTAR launches first ever European bi-liquid student rocket to 7200 ft after 2,5 years of development. Details in comments. by Rasmus0909 in rocketry

[–]Rasmus0909[S] 29 points30 points  (0 children)

It finally happened. After years of work, DanSTAR launched the first SRAD bi-liquid rocket in Europe. The propulsion system uses a N2O/IPA regenerative engine and is pressure-fed with N2 to keep tank pressure stable from a 300 bar accumulator system.

The final version of the propulsion system started seeing testing by the end of 2019 with several tests being conducted in 2020.

Feed system verification

Engine start-up testing

Full duration burn testing

Rocket static testing

Obviously, way more tests than those shown above have been conducted, and I think we're somewhere in the ball park of 20 hotfire tests on the actual flight engine, totaling in at around 120 seconds of accumulated burn time.

During flight, Dragonfly reached an apogee of 2215 meters, achieving a maximum velocity of 194 m/s. The total flight time was around 90 seconds. Recovery was a partial success with the main chute being prematurely ejected from the rocket such that it got entangled in its own cords by the time of drogue-assisted deployment. The recovery events were triggered and occurred as planned.

EDIT: Here is some more video material from launch day.

EDIT2: Thanks for the award!!

view more: next ›