modelrocket Posted October 22, 2014 Share Posted October 22, 2014 hey guys, for a school project i'm making a model rocket, the amount of fuel I'm going to use is 125 grams (not allowed to use more). I am going to test a ton of different fuel compositions, so I don't know what fuel I'm going to use for sure yet, but I was wondering if you guys could help me with the motor design. Basically I have no idea how to predict the best dimensions for my motor, nozzle etc. Also I'm wondering if someone knows HOW Fe2O3 works as a catalyst, does it help with the decomposition of the KNO3 or does it affect the carbohydrate (sugar)? Thanks in advance Link to comment Share on other sites More sharing options...
Oinikis Posted October 22, 2014 Share Posted October 22, 2014 The term "hard as rocket science" is not out of thin air, however if you want to know some science, I suggest you reading some of Nakka's work (just google). He talks about how stuff works. You will find what it means and will make sense, but to make stuff easy, keep your Kn lower than 100. Also, as a rule of thumb, your plugs should be no shorter than ID of the tube. This wont be most effective, but will be fairly simple to make and get it work. Also, for beggining 125 grams might be way too much, I'd say no higher than 40. And after all, Im thinking something like that isn't a best idea for a school project without experience, however I have no idea how science fairs happen, and if it doesn't involve stuff in action (lighting a rocket in this case), then it might work, but I still don't think this is a good idea. Link to comment Share on other sites More sharing options...
ddewees Posted October 22, 2014 Share Posted October 22, 2014 Don't forget to get video Link to comment Share on other sites More sharing options...
BurritoBandito Posted October 23, 2014 Share Posted October 23, 2014 I agree with Oinikis if this is your first rocket you should expect a CATO, and that might make it unsuitable for a school project. Frankly, I'm honestly surprised you got the ok to do this at all. For the sake of simplicity and safety I would recommend a fuse rocket. They aren't quite as impressive, and are fairly small, but they're simple to make, require minimal materials, and are about as safe as rockets get. Link to comment Share on other sites More sharing options...
modelrocket Posted October 23, 2014 Author Share Posted October 23, 2014 The term "hard as rocket science" is not out of thin air, however if you want to know some science, I suggest you reading some of Nakka's work (just google). He talks about how stuff works. You will find what it means and will make sense, but to make stuff easy, keep your Kn lower than 100. Also, as a rule of thumb, your plugs should be no shorter than ID of the tube. This wont be most effective, but will be fairly simple to make and get it work. Also, for beggining 125 grams might be way too much, I'd say no higher than 40. And after all, Im thinking something like that isn't a best idea for a school project without experience, however I have no idea how science fairs happen, and if it doesn't involve stuff in action (lighting a rocket in this case), then it might work, but I still don't think this is a good idea.Alright, I'll look into that. What is Kn?I know 125 grams might be a bit much, but I'm looking for results the rockets will be set off on a farm, set off with a remote firing system and I've made a ton of smoke bombs so I know how to not overcook the fuel. I have 120 hours of work for this project, so if my first engines fail, that's no problem.It's not for a science fair btw, it's for an.. essay? (idk the word lol). Don't forget to get video I will I agree with Oinikis if this is your first rocket you should expect a CATO, and that might make it unsuitable for a school project. Frankly, I'm honestly surprised you got the ok to do this at all. For the sake of simplicity and safety I would recommend a fuse rocket. They aren't quite as impressive, and are fairly small, but they're simple to make, require minimal materials, and are about as safe as rockets get.I do expect a CATO, but I will be firing from about 100m away. Getting the ok was alot of work And I'm pretty sure a fuse rocket wont impress my teachers, I'm in my last year of pre-university Link to comment Share on other sites More sharing options...
dagabu Posted October 23, 2014 Share Posted October 23, 2014 Perhaps you should make a motor that has a great chance for sucess. A Nozzleless black powder motor would be impressive, be inexpensive and be fairly hard to CATO. Link to comment Share on other sites More sharing options...
modelrocket Posted October 23, 2014 Author Share Posted October 23, 2014 Perhaps you should make a motor that has a great chance for sucess. A Nozzleless black powder motor would be impressive, be inexpensive and be fairly hard to CATO.Not allowed to use black powder where I live :S Link to comment Share on other sites More sharing options...
MrB Posted October 23, 2014 Share Posted October 23, 2014 Somehow "alternative fuels" are supposedly legal, but Bp isn't? I'm not convinced.Anyway, try not to get your self killed, or hurt anyone in the surroundings.B! Link to comment Share on other sites More sharing options...
modelrocket Posted October 23, 2014 Author Share Posted October 23, 2014 Somehow "alternative fuels" are supposedly legal, but Bp isn't? I'm not convinced.Anyway, try not to get your self killed, or hurt anyone in the surroundings.B!It's pretty much they made making fireworks illegal, but model rockets don't count as fireworks, and r-candy isn't in the law so it isnt illegal (yet) Also dw, my teachers won't allow me to do anything irresponsible or unsafe, I will be wearing labcoats and facemasks during the cooking and stand behind something 100m away when firing... I'm pretty sure I'll survive xD Link to comment Share on other sites More sharing options...
dagabu Posted October 25, 2014 Share Posted October 25, 2014 Huh? There's not a law against r-candy so it's legal? I don't think you understand the law. Link to comment Share on other sites More sharing options...
modelrocket Posted October 25, 2014 Author Share Posted October 25, 2014 Huh? There's not a law against r-candy so it's legal? I don't think you understand the law.that's how my country works... it's weird I know, but believe me xD Link to comment Share on other sites More sharing options...
pyrokid Posted October 26, 2014 Share Posted October 26, 2014 A simple way of tuning these rockets is to incrementally increase the core length between tests. With more core length, there is more fuel burning, so more power. Link to comment Share on other sites More sharing options...
modelrocket Posted October 31, 2014 Author Share Posted October 31, 2014 A simple way of tuning these rockets is to incrementally increase the core length between tests. With more core length, there is more fuel burning, so more power. What kind of thrust curve is optimal? Just as much thrust as your engine can handle even if that means you only get like ,5 seconds of burn time? (exagerated ) or should you aim for a specific burn duration? Link to comment Share on other sites More sharing options...
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