HALO Drop a Rocket - Science Project

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urbanJunky

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I'm new to the forum and I just started high school and I've got what I think is a pretty cool science project idea. It seems my teacher can't be bothered and I really don't have anyone else to ask, so I was hoping maybe someone could give me some pointers as to how I can accomplish what I'm trying to do.

I know this is a model rocket forum, but please bear with me. I've seen tons of videos of people sending cameras on model rockets and balloons, some as far as space on youtube. What I'm interested in doing is sending a rocket shaped package with monitoring equipment like a raspberry pi or anything else that will record altitude, temperature and speed if possible as high up as possible using a weather balloon and then have it perform a HALO drop and have the equipment record the entire event. I'm interested to know how fast the rocket will drop to the ground. There is no propulsion except for gravity involved, so the rocket does not require an engine. However I can't have the rocket crash to the ground, but wanted to have something like an ejection charge to deploy a parachute at a low but safe altitude so I can recover it.

- What hardware would be recommended for something like this? I'm sure people have sent some kind of monitoring equipment on rocket payloads.
- Can you get an ejection charge without the engine?
- I want the package to be aerodynamic to avoid tons of spin and help in a quicker drop, hence why I thought dropping a rocket would work as long as the weight is on the nose of the rocket. Perhaps even using PVC as long as the weight wasn't too much for the balloon, any other suggestions on shape or material?
- Funding for the project is very limited. I've been told the balloon and helium can be expensive, but I wanted to do tons of testing before I spend a lot of money in the end.
- Suggestions on best way to track reentry of the rocket as it's falling? How far would the winds deviate a free falling object from about 100,000 ft?

This is something that I've wanted to do for a while, but unfortunately I'm on my own so any advise you guys could give that could save me some time and $. Thx!
 
So the current altimiters for rocket can record everything you asked for and run <$100. They can also deploy the chute with an ejection charge. The biggest challenge, as I see it, is ejecting the chute at a very high rate of speed. We generally don't eject chutes faster than 80-120 FPS (55-80 MPH), which is highway speeds. I imagine your rocket will be going hundreds of mph at the point you eject. Going 100,0000 ft up will result in a rocket that accelerates as it is dropped, but will stop accelerating as it reaches its terminal velocity. The heavier your rocket, the higher the terminal velocity it will achieve. I imagine if it is small enough and heavy enough, it could go supersonic.

Next. A balloon that goes that high is big, expensive and I am pretty sure requires an FAA permit (which requires an adult). The rocket itself coming back down may require another permit as well. If this project was easy, there would be hundreds/thousands of youtube vids out there of people doing it.

But good luck with it. You will learn a lot during the process.
 
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Ignoring the permitting issues involved... I'd say that two altimeters would be needed. One that would say "break" the rocket without a drogue at a suitable altitude to slow it down some before the "main" altimeter would deploy the drogue, and then later the main chute.

I'll add that I don't have any certification, nor experience w/electronics. This was just my initial thoughts on the problem as presented.

I'd recommend a standard 3" to 4" cardboard type tubing material, as you want it to be as light as possible, as well as strong, but frangible should the worst occur. PVC is heavy, and strong. The higher the mass of the object, the more force it will have on impact.

In reflecting on it some more, I'd be surprised if the FAA would allow it to drop w/o a drogue of some sort from it's separation with the balloon.
 
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You should look into joining existing programs through universities and aerospace companies. FAA is unlikely to approve any such drop over the continental USA from such altitude and the cost of liability insurance would probably be way too much for an independent project. I encourage you to keep dreaming big and continue your education.
 
Ok this is in theory ( have not done any Sims) a rocket at or less than 10lbs minimum diameter 75mm two stage with to very long burn L's you would need to be a L2 if you can keep under 5k NS . It would be a long shot at best . Most likely it would be a L3 attempt and a class 3 at that . Not to discourage you but do some Sims with open rocket or roc SIM and see what it would take
 
Thinking about the electronics here, most rocketry altimeters won't work. When you turn on a rocketry altimeter it takes samples and set itself to zero. Launch is detected by a g-switch or rapid change in altitude which you won't get as a balloon ascends. Your altimeter would need to be modified to allow firing charges without a launch detect.

Charges can be used but you must be 18 to buy or handle BP. Using a drogueless dual deploy configuration would probably do the job, but separation would be at terminal velocity which might be risky.

There are regulatory and insurance concerns. You should get in ouch with a really strong science program (university) to proceed.
 
Thank you so much for your feedback. I knew that dropping the object that high up would go fast but I wasn't counting on it going that fast! I did find a NASA site that helped me get an idea what the terminal velocity of a 3lb object with cross section of approximately 5 inches, it estimates it at 545.45 mph. As cool as I think it would be to see something fall that fast, I think everyone here agrees that it's going to be very difficult to stop something traveling at that speed with a parachute.

After some number crunching perhaps a near space drop of a projectile to earth may sound really cool, but could get me in trouble. Perhaps if I change the experiment a little I could still make it work. What if I could control the height of the balloon and have it drop from perhaps 2000' instead of 100,000'. Have it free fall for about 1500'. I estimate terminal velocity to be around 65mph which is well within the range that CZ Brat mentioned and a parachute should permit for a safe recovery. I'm going to assume that I'll need a couple of altimeters for this though. One to pop or release the balloon once it reaches 2000' and another when it gets to 500' to deploy the parachute. Does this sound a little more doable? I guess I'm going for the how fast does the penny travel if you drop it from the top of the Burj Khalifa tower experiment.

I also did some digging on permits and license and did find a site that stated that a license was not needed. I'm new to the area, but had some people here on base mention to me that there are some salt flats here in Utah that would make a good place to launch my experiment. I'll just have to do a lot of testing to ensure that the altimeters work when they are supposed to!
 
No motor means rear ejection and if you do it in stages you could decelerate to an acceptable level. Might tear some laundry up but if planned properly I would think final chute would work. Good luck.


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You're lucky to be out west where there are large open spaces for your project. The site you mentioned is for weather balloons, and while there may not be restrictions on flying these, you need to look more at dropping something from one.

You also need to check you math on the terminal velocity of your vehicle. A skydiver in a spread eagle position will reach 110 MPH within 6 seconds of exiting a plane. Having seen rockets come in ballasting from around 2,000", I can assure you it will reach a speed well over 65 MPH.

Keep working on the concept.
 
Questions/comments. Why do you want to drop a rocket-shaped object? You can make other shapes that will be stable while falling, especially if you use a small drogue chute or streamer.

Terminal velocity is reached when the force of gravity (actually the accelleration due to gravity) and aerodynamic drag are equal to each other. This means, when F=ma (force due to gravity)=mass x g (gravitational accel.) AND F= 1/2 C A p v^2 (force of air resistance) = 1/2 x Coefficient of drag x cross sectional area x density of air (rho) x velocity squared .

Weather balloons (radiosondes or rawinsonds) usually burst at about 80,000 feet or so, depending of what size balloons are used, how full they are filled, etc. Weather balloon instruments have a small parachute attached so that when the balloon breals, the parachute immediatly opens (or will open as soon as there is enough air for drag)

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I don't know where you're located, but the National Weather Service launches weather balloons twice a day, at Greenwich Mean Midnight and Noon. If you live near one, you might check with them. I bet they would be glad to have you watch.

I'm assuming you're going to want to get your experimental payload back. You'll have to have some way to track it. I don't think you'll be able to follow it with your eyes. You'll probably need some king of radio transmitter to either provide a beacon that can be located with a directional antenna, or better, have a small GPS system that can send location back on a radio signal. This is going to add a layer of complexity, but this is a fairly complicated project.

Others have done similar projects. One place you can read up on some is The Register (https://www.theregister.co.uk/) a technology discussion website out of England. They've done several R.Pi balloon flights, a paper airplane drop from a balloon, and have a rocket glider balloon drop project scheduled.

This sounds like a lot of fun. Please keep us informed. We'll be glad to answer as many questions as we can (this forum is a great resource - folks with all sorts of experiences). Oh, and there will also be people who will tell you that this project is illegal, impossible, and shouldn't be done because it's too hard (they're all wrong).
 
Well... good thing I have till my senior year, I got a lot of stuff to learn it seems. I think I'll start with getting familiar with rockets. It seems more along my budget and I can learn about the altimeters, engines and so on. The more familiar I get perhaps I can adjust the concept and see if it's at all possible. My science project can't be illegal if I'm going to turn it in so I have to play by the rules. I'll check the forum and see what's recommended for a noob like me! Thx for all the great input, I'll come revisit this post once I get more ideas or have some results!
 
Junky,

Find a group that launches a weather balloon near you. You can find upcoming launches on arhab.org and spacenear.us . Many of them can take extra payload, so you get to launch your sensors into space with minimal effort and budget. This will help you figure out what you want and how to go about it.


-Alex
 
There are several universities around my area, I'll ask around and see if any of them have any programs or something that I can get involved. Thx for the information guys!
 
Since there is no motor, one good way to deploy the parachute might be out the back of the rocket to prevent airframe damage.
 
You should look into joining existing programs through universities and aerospace companies. FAA is unlikely to approve any such drop over the continental USA from such altitude and the cost of liability insurance would probably be way too much for an independent project. I encourage you to keep dreaming big and continue your education.

After reading the FAA requirements for a free balloon flight linked in post 15, it turns out that no permit is required from the FAA. The FAA requires notification only, plus adherence to the rules published.
 
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