In my rocket science class at school, we are building a rocket that is supposed to be able to fly a mile high carrying a 1 pound payload, which doesn't include the weight of the altimeter. Also, it should land within a recovery radius of 2500 ft with the wind settings I added to my open rocket file which I will upload. We have a $1000 budget and this is what I have so far, but I am struggling. I mostly need help lowering the recovery radius and squeezing out some more height because I haven't even added the weight of the charges to the design yet. I don't have many engine options but they are all in the file, and they are different prices. Our budget can't do the L engines or the J300 series ones. I need help please.
Mile high rocket on $1000 budget w/ 1lb payload help.
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Also, my fins are supposed to be made out of aircraft-grade birch plywood, but I couldn't find that exactly on Openrocket and I don't know if that will cause issues in my sims vs. real life. And does anyone know of a good place to buy aircraft grade birch plywood for cheap? How thick do you think my fins should be.
If you're using OpenRocket, please save your file as ORK rather than RKT. It will preserve more of the data.
PayLoad
I don't do spirals
WARNING: My Opinions Only -
Weight is not a bad thing - 1.5lbs to 5300 feet is not too difficult - use the weight as nosecone ballast, call it payload. Jolly Logic chute release will get you within a few hundred feet of the launch pad.
5lb starting weight loaded, 32mm airframe, H or I will get you there.
For $1000, you can build 2.
Just my humble opinion from experience
Weight is not a bad thing - 1.5lbs to 5300 feet is not too difficult - use the weight as nosecone ballast, call it payload. Jolly Logic chute release will get you within a few hundred feet of the launch pad.
5lb starting weight loaded, 32mm airframe, H or I will get you there.
For $1000, you can build 2.
Just my humble opinion from experience
DeepOvertone
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A few questions. Does it have to go "as close as possible" to one mile high, or "at least" one mile high but higher is fine?
Is the 1 lb payload a specific device? or can it just be 16 extra ounces of whatever?
Is the $1000 budget for everything?? or are there items you already have that don't count towards the budget(such as altimeter and JLCR)?
Is the 1 lb payload a specific device? or can it just be 16 extra ounces of whatever?
Is the $1000 budget for everything?? or are there items you already have that don't count towards the budget(such as altimeter and JLCR)?
I forgot to mention that for this class I have to use a hybrid engine that is purchased from the organization that runs the class. It is $330 for what might be the best option, which is the J190 with FX fuel grain. But it is the cheapest I can go with the engines. The next ones up are all $550 and that is just too much for the engine. What could I do with the J190?
boatgeek
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A few comments:
Cost:
Go to cardboard tubes, from LOC or someone similar and also a plastic (not fiberglass nose cone. That will save some $$ and weight.
Reducing weight also reduces motor cost.
Weight/Cost:
Go to a single main chute. 48" is probably OK, though you may need 60" to get a descent speed around 20-25 FPS.
Go with a smaller drogue. You probably only need a 12" or so drogue. You want your descent speed under drogue to be around 80-100 FPS to minimize drift.
Shift your fins nearly to the end of the rocket and you may be able to make them smaller. Personally, I wouldn't sweep them aft that much because they're more likely to get damaged on landing. Personally, I like fins that are square at the back or swept a tiny bit forward.
Drift:
Set your main lower, probably to 500-700 feet. That will help a lot, as will reasonable size main chutes.
Cost:
Go to cardboard tubes, from LOC or someone similar and also a plastic (not fiberglass nose cone. That will save some $$ and weight.
Reducing weight also reduces motor cost.
Weight/Cost:
Go to a single main chute. 48" is probably OK, though you may need 60" to get a descent speed around 20-25 FPS.
Go with a smaller drogue. You probably only need a 12" or so drogue. You want your descent speed under drogue to be around 80-100 FPS to minimize drift.
Shift your fins nearly to the end of the rocket and you may be able to make them smaller. Personally, I wouldn't sweep them aft that much because they're more likely to get damaged on landing. Personally, I like fins that are square at the back or swept a tiny bit forward.
Drift:
Set your main lower, probably to 500-700 feet. That will help a lot, as will reasonable size main chutes.
The $1000 budget is for absolutely everything besides the launch pad. And the goal to get gold rewards is for the rocket to + or - 100ft off of exactly a mile, so if it goes too high that is bad. The payload can be basically anything, just it has to be able to perform some sort of test or experiment while going up. But that is a very small thing. We are planning on having a fifth-grade class come in and make the payload for us to see what they come up with. This is a whole class project at my high school also, just for clarification.
Do you think a cardboard tube would fall apart from going too fast?
DeepOvertone
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You're not likely to go too fast on a J190 and only to 5000ish feet. As long as its built up to normal standards for a good high power cardboard/wood rocket, you should be fine.
Not even close. Cardboard may not save much (or any weight vs. Quantum Tube, but it should definitely save you some money.
boatgeek
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You'll be fine at these speeds as long as you use the high power grade cardboard (not the Estes thin wall stuff). If you were getting up near Mach 1.5-2, I'd worry more. If you have the budget, use a slightly better grade of epoxy than the 5-minute stuff from Home Depot or the hobby store.
TimothyG
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Jolly logic chute release would be a bad idea given your budget as it would eat up a chunk of it. I was a big fan of jolly logic products but for the price given a student group, I'd recommend against it. A line cutter is simple to make for a dollar or so in the material if you have access to a lathe. Also a great introductory project for learning how to work with a lathe. I'd go eggtimer quark redundant pair with apogee charges and line-cutters. You can get very lightweight with this setup and it's well within the limits of the electronics without taking a bite out of your budget. If you have a problem with getting/making a line cutter pm me and I may be able to help. I make them for a few cents and treat them as single-use or disposable depending on the application.
I have no clue
Well, you better get it together. First things first.I have no clue
heada
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https://locprecision.com/product/hyperloc-835/
That'll take most hybrid motors from smaller H motors to bigger K motors, big enough to support nearly any electronic deployment for dual-deploy (close recovery), accept the 1lb payload in either the av-bay or the nose and is only $145.
https://eggtimerrocketry.com/eggtimer-quantum/
Pair that with an Eggtimer Quantum to control recovery events for $45
That adds up to $190 so you have $810 for motor costs.
To get to 5000', adjust the mass of the rocket (add weight to the CG point) but make sure to stay above the 5:1 thrust to weight ratio.
You can swap the fins for higher quality "aircraft-grade" Baltic birch. You can get that from a proper woodworking store like WoodCraft or Rockler or from AircraftSpruce.
That'll take most hybrid motors from smaller H motors to bigger K motors, big enough to support nearly any electronic deployment for dual-deploy (close recovery), accept the 1lb payload in either the av-bay or the nose and is only $145.
https://eggtimerrocketry.com/eggtimer-quantum/
Pair that with an Eggtimer Quantum to control recovery events for $45
That adds up to $190 so you have $810 for motor costs.
To get to 5000', adjust the mass of the rocket (add weight to the CG point) but make sure to stay above the 5:1 thrust to weight ratio.
You can swap the fins for higher quality "aircraft-grade" Baltic birch. You can get that from a proper woodworking store like WoodCraft or Rockler or from AircraftSpruce.
mikec
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Does this organization really provide so little guidance and mentorship to students that you have to get these basic questions answered on TRF? That seems pretty crazy to me.
How does the system to deploy the recovery system work and what all do I need? Can I just buy a secondary charge that goes off at a certain height and pops off the nosecone or what? Is it different for my drogue that deploys from the middle?
Yeah, we pretty much are taught a bunch of basic physics concepts and told to apply them to our rockets. In the first semester, we built 3 very small model rockets that we had to design ourselves but this is our first large one and they aren't giving us many hints.
PayLoad
I don't do spirals
No attempt at flaming the OP, but I must agree - You will get great answers here from a bunch of great people, but alot of this stuff is common knowledge that should be known before you launch an Estes bird.
Yeah, we are probably a bit behind. My high school has a physics class for a reason so I think they should spend more time teaching us about the individual parts of a rocket and how they work/information about them. But I have learned a lot from this forum so far, so thanks, everyone.
mikec
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I think you should buy and read a copy of Modern High-Power Rocketry 2 by Mark Canepa. Unfortunately it has little information about hybrids, but I presume you aren't going to have to operate the hybrid yourself? That would not only be difficult but actively dangerous.
heada
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Your flight electronics control the recovery events. That is normally 2 events but some electronics can do more than 2 and some people use redundant electronics which would double the number of events. Some are single event but require something else for the second event (motor ejection, different electronics, etc.)
In my suggestion, I named an Eggtimer Quantum which is a 2 event altimeter. Those events are programmable but by default the drogue event happens at apogee and the main event happens at 1000' (I think, I always lower it to about 500') The electronics activate a pyro circuit at the time of the event and you have an e-match or something similar attached to that pyro channel. The e-match will start the deployment charge which is normally some form of black powder. In a standard setup, the av-bay is centrally located in the rocket and you put an e-match on either end of it (both forward and aft, aka both top and bottom) They can be setup either way but most people place the drogue and it's charge aft (the bottom) of the av-bay and the main forward (the top) of the av-bay.
All this said, find a local club that does high power rocketry and get a mentor. They'll walk you through all these things.
In my suggestion, I named an Eggtimer Quantum which is a 2 event altimeter. Those events are programmable but by default the drogue event happens at apogee and the main event happens at 1000' (I think, I always lower it to about 500') The electronics activate a pyro circuit at the time of the event and you have an e-match or something similar attached to that pyro channel. The e-match will start the deployment charge which is normally some form of black powder. In a standard setup, the av-bay is centrally located in the rocket and you put an e-match on either end of it (both forward and aft, aka both top and bottom) They can be setup either way but most people place the drogue and it's charge aft (the bottom) of the av-bay and the main forward (the top) of the av-bay.
All this said, find a local club that does high power rocketry and get a mentor. They'll walk you through all these things.
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Nytrunner
Pop lugs, not drugs
Question: Is your team even allowed to work with blackpowder/BP substitutes? That's how most dual-deployment (electronic deployment) is done with high power hobby rockets, and that's how our off-the-shelf recovery computers work.
My thinking is your age group needs an adult to purchase and handle the blackpoweder, so competition is trying to encourage you to think outside the box and design/make creative solutions for deployment and recovery.
Here's a video explaining how to do a traditional dual-deployment electronics setup, but I'm not sure that's an option for your group unless you have an adult to legally handle the poweder/charges (plus there's sourcing ematches and all that to get into)
https://www.apogeerockets.com/Advanced_Construction_Videos/Rocketry_Video_27
Would I want to pair the egg timer quantum with one of these: https://the-rocketman.com/chute-release/
Or is the egg timer enough on it's own?
Or is the egg timer enough on it's own?
Yeah we have adults there who will do all the work with the black powder, but we have to set it all up, and their only job should be loading any fuel and launching it.
heada
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A chute-release needs an apogee event to happen at apogee and it can then handle the main event at it's configured altitude. This is a 1 event device. Since you're talking about a hybrid motor, there is no motor ejection charge so you would need something to handle the apogee event. The Eggtimer Quantum is a 2 event device meaning it can handle both the apogee event and the main event. If you pick the chute-release, you need something else as well but if you pick the Quantum, you only need the Quantum.
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