mardlamock

Thats some expensive stuff you ve got there

Thanks! It is a scratch build, the casing is PVC but has been painted to look like that, that fin has been placed a bit off center and in a small inclination, but it will be compensated with the other fins, making it spin to stabilize. The bulge in the middle is due to the PVC coupler being of a larger diameter than either the motor or parachute bays, I had to smoothen it out, it looks weird due to both parts not being fully coupled, once they are it will be a much smaller dent. Even the motor is homemade, R-Candy as propellant and more PVC for the combustion chamber, according to the simulations it should be providing around 700n of thrust. I still dont know what name to give it, so tell me your suggestions!

I have been building this from scratch, 3000m max height, 1000kmh max speed.

So, due to the fact that there are a finite ammount of observations that can be taken into account when building a model of reality, there is an infinite number of possible models? I know that science should use the simplest, but does that mean that any interpretation of a physical system is valid (so long as you have built a model that is accurate)? Could one then build a model that explained QM in a fully deterministic way?

Hello everyone, I have been entertaining myself on the Flat Earth society forums and It got me thinking, Could one construct a complex enough mathematical system to describe a flat earth universe? One that gave results, with their own interpretation of course, similar to those of heliocentric models, even taking relativity into account. There is only a finite ammount of observations we can perform, and therefore infinte functions that can satisfy the mesurements acquired from those observations, at some point it would probably break down and need to be fixed, but could you with enough time construct such a model? Anyways, thanks a lot, sorry if this question is sort of stupid but I just wanted to know what you guys thought.

So does that mean that according to you I cannot possibly understand it? In the US I would be preparing for AP exams, its just my school's ....ty math education that means I wont learn it formally until next year.

No one?

Im building a dead reckoning arduino based system for a scratch built rocket that will go to about 3km in height and 320m/s. The engine is basically ready, it is a uses a pvc pipe as the combustion chamber, a concrete de laval nozzle and r candy as fuel, generates about 800 newtons for 1.25 seconds. The airframe i also pvc, though it is 10cm in diameter but much less thick. Its a fun little project, its making me learn a ton of math and physics (more physics now).

Going up to 30km may mean that you can use less dv due to less drag, but you are still going to need at the very least 8km.s of dv to get into LEO, a rocket that size would not be in any way lifted by a balloon, and if you do manage to get it in the air the fast winds will probably destroy it.

I have, there is one rocketry club I tried to contact but it seems they are not active.

Hello everyone, I just wanted to know what you guys thought about the idea that the universe is basically a cellular automata with simple rules that behaves in a deterministic fashion in a discrete time. I ve been looking a bit into the idea and it sounds quite amazing, stephen wolfram does an awesome job of explaining it in my opinion, but I wanted to know what you guys thought of it as it would reject both randomness and a continuous time.Thanks!

It isnt chinese anymore, its like reading shakespeare, making progress but not quite there. I find myself lacking not so much the mathematical knowledge but rather the physical one, for example, not knowing where fluid mechanics comes from, bla bla bla. I can apply formulae (after looking up what each symbol means that is), but it is like doing guesswork due not not understanding what it all means until i get the result.I enjoy learning that stuff though, its hard the first time, but fun once you see the progress you ve made.

I taught myself single variable calculus and a bit of diff equations (not too much of the latter).

You got me wrong, I really want to learn the details but not have to go through 10 different books for each of the systems for a rocket. I am using exactly that book (when i started it was like reading chinese).

In most countries they arent illegal, this sounds hilariously fun dude, good luck!

I didnt ask them to tell me everything, I just asked for some good reference books regarding rocket control systems and engine design, I had found one that explained quite a lot of the engine design aspect of a rocket, but it was quite hard for me to understand as it (for me) required you to have a ton of previous knowledge. I will try to get the email of someone in the mech eng department of a university, I know for sure that one is doing work on rocketry but I havent been able to find specifically who he is and what he is doing. Christok, the purpose of what I am writing is so that other non specialized people like me dont have to go through all of the hassle of looking for information on the different systems present in a rocket and figure out how to use that information how to build one. I will take a look into those journals you talked about, thanks!

I ve been trying to get in contact with the universities here, but none of them have rally payed me any attention whatsoever, I ve called at least 10 times and none of them did they actually contact me with an engineer or someone who could mentor me. I even went to one of the few companies here that build satellites (satellogic for those wondering) and spoke them quite a deal about what I was doing and got to meet their team and see how they controlled their spacecraft, but in the last few months I havent been able to get them to answer my emails (most likely due to them being too damn long). I was also wondering if publishing my findings on a magazine or such would help me get accepted into college in the US, could it? My grades in the sciences are pretty good but subjects like literature make my gpa quite a lot lower, thats why i really want to know if doing these experiments is taken into account. Thanks everyone, i will keep you updated!

Thanks for the reply man! I know it is common knowledge, thats why I wondered wether it is actually adding anything or just explicitly appyling the bulk of the theory. I will still continue with the project just for fun and to try and learn some things on my own, given that most I cant really access the papers that actually talk about the topic at a great extent I will just continue experimenting. I will follow your advice, I greatly appretiate you taking the time to answer. Thanks!

Thanks a lot everyone! First off, I really dont care what journal it is published on so long as it can be easily accessed by people to critique it and maybe used for their own projects. I do not believe it adds a lot to very experienced people who might read it, all I am doing is applying well known simple methods to achieve the results wanted. Those are to make a paper which can be used by people who are not specialized in the field to design and build a rocket according to their own requirements whilst keeping it all as low cost as possible. I havent seen any papers really dedicated to the different steps involved in doing so, all of the ones that are somehow related mix 3d printing to rocketry, but having tried 3d printing myself I can say it is expensive if done at a smaller scale, same results can be achieved with lower budgets and off the shelf materials. These methods could be applied by small groups of people wanting to do a variety of things, from cloud seeding to getting readings from the atmosphere, or maybe testing low cost inertial navigation systems. Does that count as adding knowledge? I appreciate the help and will be updating you guys as it becomes something a bit more readable and structured. Thanks!

Hello everyone, for the past few months I have been building a low cost high powered rocket with an arduino based parachute deployment system and dead reckoning (highly inaccurate though, I really dont get kalman filters). I have had to learn a lot of calculus (I wont even see derivatives in school till next year) and a bit of nonlinear diff equations, my question is though, how technical do scientific papers have to be in order to get published? The paper describes the design and construction of the rocket, all of it using off the shelf materials, the different tests performed (2 thrust measurements, 7 static tests in total, 5 failures) and problems one might face when deciding what to build it with. I have also got an euler approximation of the differential equation that describes the motion of the rocket under aerodynamic drag, taking into account changes in the drag coefficient as a function of mach number and the change in air density, as well as simulation of the rocket engine using external software (its called burnsim), I do not know if this would be enough for the paper to get published though. The parachute deployment is pretty basic right now (just a simple timer, run and light the candle in a given time frame), but I am trying to improve it, my biggest problem is that the 6dof imu that I am using is pretty flimsy, and considering that the rocket will experience around 30gs ( if the pvc can withstand the 8.5 mpa that is) I doubt it is a good idea to put it on a rocket. Anyways, I just wanted to know what you guys though and if this could be considered a half serious thing or it wont be published at all, thanks!

So, only numerical approximations? That sucks.

Hello everyone, I was just wondering if there is an equation that can describe the optimal trajectory for a rocket launch. Relating drag to velocity, altitude to air density, the drag coefficient as a fucntion of the mach number, the cross sectional area to the orientation with regards to the velocity vector, and also orbital mechanics. I know its a long list but if one was to actually have that equation then you could potentially get the least use of delta v and optimize rockets a lot. Thanks!

Good luck building a hybrid rocket, you will probably die in the process. Unless you are willing to waste a lot of money on a simple egg you should go for something more simple. You need an engine that is capable of providing enough thrust to lift itself, the 3 kg of extra structure you ll probably need (water rocket with thrust control), develop an accurate enough dead reckoning system to feed to the control system and get all of the money for that. I myself am currently building an R candy rocket with an active stabilization system that will have to stabilize it at almost 900kmh by moving fins around, so im more than interested in whatever you can develop and would gladly appretiate if you sent me some of what you have thought of.

Thank you very much, i had no idea what i was doing had a name and everything, i just thought of it on my own and ended up with that method. I also thought of doing a more accurate method where i do the integrals of the rocket s acceleration due to its own thrust (f/m(t)) and get a better result. Thanks a LOT for the code, comments made it much easier to understand. My math teacher got me a book on diff equations of these sorts and i will be reading that to try and find an exact solution to the problem, that would make it i think a lot easier for when i put all the code onto an arduino and have it log data and correct its path, that will happen much later though. Do you guys happen to have any idea on how it is done in real spacecraft, do they use really good approximations or do they try to solve the equations exactly? I ve been looking into what might make in the futurue a good business, small disposable launchers capable of taking multiple cubesats into orbit and for a decent price, also giving flexibility to the companies wishing to use them. Once again, Thank you very much!

I know that solution but that is not taking the density of air changing as a function of height which is quite important when it comes to the max height of my rocket, considering it has an impulse of about 800ns. The general equation i am looking to solve is this: k/(m(t))-r(x´(t))*n(×(t))/m(t)-x´´(t)=0. In my case, m(t) would be the rocket s mass as a function of time, k the force it exerts, r(x´(t) the velocity s part of the drag equation, and n(x(t)) the density as a function of height .I ve been trying to solve it by using the regular e^rt method used in homogenous diff equations but it seems to get quite complicated. I would be more than pleased if you could help me set the equations up in Octave and solve it. This will be useful because if I want to build the flight computer i ve been thinking of it d have to solve these equations on the fly to estimate apogee and then even more complex equations for the max deflection angle of the fins and such. Thank you very much!