RocketEnthusiast101
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Hi. How much thrust would be required for a rocket reaching an altitude of 100km and also what set of formulas should I be using?
Thanks for the response. So the altitude gained only depends upon fins, the diameter of tube and rocket weight (after everything has been loaded and the rocket is fully assembled?)How much does the rocket weigh? What is the diameter? How many fins?
Thrustcurve has a model rocket sim that will give you an idea as a starting point. Use OpenRocket or RockSim to give you a more accurate idea.
Hi. How much thrust would be required for a rocket reaching an altitude of 100km and also what set of formulas should I be using?
Hi. How much thrust would be required for a rocket reaching an altitude of 100km and also what set of formulas should I be using?
J^2 = m^2V^2 = 2m * mV^2/2
30,000,000 = mv^2/2
so J^2 = 2m * 30,000,000, for a 200N rocket m=20kg
so J^2 = 40*30,000,000
J ~ 35000 N-s if you can generate that much energy a 20kg rocket (very unlikely). But I will leave it up to the student to do the calculations with more realistic heavier rockets.
The mass assumption is wrong. Plug in the mass of q motors, double the result like I said and it will converge to a realistic motor size.Rough indeed.
I get something like 32,000 N•s -- but close enough for a Fermi estimate.
That's an O motor, yes? The OP would only need a to certify L3 for their space-shot >smile<
If the OP hasn't been scared off -- take a look at this
https://openrocket.info/documentation.html
for an insight into why the answer to the question isn't a plug-and-chug computation.
Hi. How much thrust would be required for a rocket reaching an altitude of 100km ?
I really like this response. Thank you for taking the time to respond properly.I'm going to answer a slightly different question that is more useful:
How do I figure out how to get to 100 km? You run some simulations. For starters, download OpenRocket and any OpenRocket file for a 4" rocket with a 54mm motor mount. You can get them from manufacturers. Don't worry that they're not exactly right, it doesn't matter for this exercise. Fool around with lots of different motors, and look at the differences in speed, acceleration, and altitude when you run the simulation with a high-thrust motor and a low thrust motor that have the same impulse. Look at the same factors for motors that have about the same average thrust but widely different impulses.
Once you've done that and you have some thoughts about how you might get to 100 km, build a sim yourself. See what you have to do to get it to 100 km. Again, don't worry if the sim is impractical, just add motors and reduce weight until you get there. Once you have that, try to get a realistic rocket that gets to 100 km. It'll either be a custom motor (like Go Fast) or multiple stages (I'd guess 6" to 6" to 4"). That will give you many of the answers you seek.
You don't need equations. Until you're a professional, the fine folks at OpenRocket, RockSim, and RASAero have already done the hard equations work for you. You just need to use the tools already available. Also, if/when you are a professional, unless you're actually on the team writing the professional grade simulator code, you won't be using massive equations either. You'll be running simulations and letting the computer do the work.
Imitation chemist here: osmium perchlorate would have molar mass that's way too high for decent Isp. Highly concentrated perchloric acid can be thought of as hydronium perchlorate -- (H3O)ClO4 -- but being as it is a liquid, and decomposes violently when it contacts organic matter of any sort, probably there are better choices.
... osmium perchlorate would have molar mass that's way too high for decent Isp ...
Well, color me chagrined. I only got as far in my thinking as the notion that more mass per particle would mean more impulse for a given exhaust velocity. I didn't take my back-of-the-envelope algebra far enough (or even do any algebra on the back of anything).
The mass flow rate is, indeed, on the bottom of the Isp ratio. Oh well, fortunately its not my job to be mathematically rigorous about this kind of thing ... wait ... damn.
I would suggest the Bitcoin mining set of formulas, because 100km is going to cost you some serious coin.Hi. How much thrust would be required for a rocket reaching an altitude of 100km and also what set of formulas should I be using?
Hi. How much thrust would be required for a rocket reaching an altitude of 100km and also what set of formulas should I be using?
Yeah, most of the experienced rocketeers in the NAR and TRA have never exceeded 5km. And it is very hard to find a place where any more than 2 or 3 km is even legal.
There are about a half dozen 50k waivers AFAIK: KS, MT, AZ, NV IIRC. 45k is the highest most folks can plan for, and even that isn't exactly common.5km is about 16000 feet. It seems that most clubs have a around 10-15K waiver so your estimate makes sense. But let's take a more modest goal. How common is it for people to get to say 50k and above at events with high altitude waivers? What's a more realistic upper limit for a hobbyist?
There are about a half dozen 50k waivers AFAIK: KS, MT, AZ, NV IIRC. 45k is the highest most folks can plan for, and even that isn't exactly common.
I thought there were a few events with higher waivers such as balls? They go to 100k right?
Depends on if it's a Black Friday sale or not :-DWhat’s the I_sp of a $50 bill?
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