Rockoon to 100km

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I don't think that a 4000g balloon is going to lift 50 lbs, I may be wrong but that seems rather high. I've used 2000g balloons and we use .5 lb payloads on them. I think you might have the maximum burst diameter confused with how much you can fill it on the ground. Remember a 8 ft diameter balloon on the ground will expand to 30+ ft in diameter at altitude. So I'd get some real numbers on this before investing too much into the rest of it.

There aren't any real good programs that will just do good rockoon simulations. You can use several in conjunction to give you a decent idea though.

You aren't going to "make" a balloon drift anywhere, you can plug in some high altitude wind data and get a decent idea of its predicted path. But the winds can drastically change direction and strength in just a few thousand feet of altitude. I don't really know of anywhere that posts high altitude wind data, most wind data recorded stops at around 50k ft. So you will need to fly your own weather balloons to make sure that the balloon with the rocket is going to go on its expected trajectory.

Launching on land and hoping the wind will take it over a body of water, especially a lake (even if it is a really big lake) will be a tough sell to the FAA. I feel like your potential debris landing locations are going to be massive since you cant really control the direction of the launch all that effectively once at altitude. You will just have to talk to the FAA on this one as for feasibility regulations wise.

If you want to make this easy on yourself I'd recommend going out on a boat in the ocean and launching it from a hundred miles off shore or more. That way you won't have to worry about as much. But doing that has it's own set of problems.

Your doing fine asking questions just know that the internet predictor you linked is only using weather models for its information, and isn't going to give you an answer that will match up well with reality on any given day.

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https://www.randomengineering.co.uk/Random_Aerospace//Balloons_files/widget23_markup.html is a burst calculator for standard weather balloons.

You will need a 6-DOF monte-carlo simulation program that will calculate thousands of trajectories to perform the mandatory splash zone impact calculations that is required for a Class 3 flight due to altitude even through it will be a Class 2 rocket . Since you have no trajectory control the splash zone is very large, so you are required to conduct this type of operation at least 100 miles off-shore in the Atlantic as you most likely will not be able to insure the rocket will launch vertically and a rocket capable of exceeding 100 km could travel over 100 km horizontally in any direction when launched from 30 km.

Regardless it will be very expensive if you can get permission to do it.

Bob

saadzmirza said:

Thanks for the input, Xtrain.

I can assure you that from my experience, the TA4000 will be able to lift 23kg to 31km.
If you input the data on the Random Aerospace balloon calculator I linked to earlier, the TA4000 has a burst diameter of 15.06 meters (50 feet). Using Hydrogen, (My group has access to free lifting gas due to a generous donation from the local welding company), the balloon will be able to lift 50 pounds to 100K feet at 4m/sec.
These are big balloons. Volume increases faster than area.

The wind predictions, from my experience with balloons, are quite shaky until the final GFS wind models about 12 hours before launch. If the ccalculations are done right, the landing is within a 15km radius.
Of course, it is designed for balloons, not rockets.
Overall like you said, at best we'd be able to say the balloon will probably drift over this large body of water.
The chance a favorable situation to arise would be very minute for landing, however, it does work out for August 5th interestingly. Try a launch from 100m launch altitude, 4m/sec ascent rate to 33000 meters(assuming a payload well under 15kg) at 1340 Zulu from the coast of Lake Ontario near Lockport, NY.
Hoping for it to descend back over land may be a bit too much.


I am still puzzled as to how to use these programs. Could you give me a few pointers?
I tried to import some rocksim files and load up some motors, but changing the launch altitude makes things screwy.
Any suggestions for a launch veichle as well?
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If I had to bet, Lake Ontario is not a big enough body of water to do the flight you want, especially since the lake is pretty much surrounded in major cities. I don't think lake superior is large enough either.
So for the entire baloon's flight path, draw a circle around the balloon at any give point in its flight 100 miles in radius. That is the area that you will need to ensure that is clear of any thing to hit. Which is why bob and I recommend you go 100 miles offshore in a boat.

If you set the launch pad altitude to 100k ft. in rocksim and vary the launch rail angle, that will give you some representation as to how high the rocket will go. Otherwise follow along with some of the tutorials they will tell you how to make your first rocket. https://www.apogeerockets.com/Rocksim/RockSim_Video_Tutorials
I did some quick simulations, by the time you include the weight of the launch rail, and launch electronics and such, you are going to have a tough time to get a rocket that will flight 200k ft. above the balloon's max altitude using just one of those balloons.

If you have to hire a boat to take you out to sea for the launch, I'd say $10,000 would be a very conservative estimate of the total project costs if the boat captain is nice to you. With about a 2 year development time considering you guys haven't done any HPR yet. This would be hauling some pretty serious behind on the project too.

For now if I were you, I would put the whole balloon element on the back burner for now. Focus on the rocket that you will want to use for the launch, get your certs, and prove out its design. By the time you go through that process you can re-approach your balloon launcher and have a better feel for your requirements. I know that rocksim is a bit obtuse in some ways on its interface. That said, if it's puzzling you, you still have quite a bit of homework ahead of you before you can start to seriously pursue the rockoon.

For your launch vehicle, it depends. It depends on the skill set and experience that you have available for your project, and in what areas you want to accept risk. If its more than alright for the project to not work, I'd say a two stage minimum diameter would probibly get you the most altitude but would carry a ton of risk of failure with it. If you want to remove more areas of risk, but increase cost a min diameter big N or O motor might be a good bet. 50 pounds is pretty damn light to get something to go over 200k ft. considering you need to carry you GSE with you as well.

The president for my school's rocket club wants to do a rockoon as well. I, as well as every other rocketeer and engineer I've spoken with, has spoken out against the idea. First, the landing area is increased by 100 miles across, in addition to the rockets flight. And you can't be sure the rocket is going to go straight when you launch from altitude. How do you intend to keep the launch system vertical during ignition, how fast does the rocket need to go before the fins can provide stabilization to the rocket, what tracking system do you intend to use that can track above 60k MSL&Mach 2?

Do you intend to mix your own propellant and custom build the rocket, or buy an off the shelf solution?

Launching a balloon to 100,000 ft is easy, launching a rocket to 100,000 ft is far less so, and you need a rocket that can go roughly 100,000 ft MSL from sea level to reach space from 100,000 MSL.

From experience working a rockoon design for a large diameter rocket for an entire year, ditch the idea and have your club learn how to launch rockets first, learn electronics and staging second, and propellant manufacturing third.

There is a reason people don't do rockoons, and it's not because they're so cheap, easy, and effective.

Maybe I made an embarrassing calculation error, but it appears to me that you can lift way less then 50lbs payload with your balloon.

According to Wolfram Alpha, the air density at 100kft is 17g/m^3. Substituting air with hydrogen, should result in a lift of about 15.7g/m^3, or about 8.2kg for a 15m sphere. This assumes a zero pressure balloon. A latex balloon, that is inflated to its burst pressure, will compress its contents, resulting in a higher hydrogen density and therefore even lower lift. Looks like you have "less than 8.2kg", from which you have to subtract the weight of the balloon, the launch guide and other gear, available for your rocket.

Reinhard (please correct me if I'm wrong)

Edit: Yes I'm wrong, made a stupid error above, but I won't tell which one ;-)

edwinshap1 said:

The president for my school's rocket club wants to do a rockoon as well. I, as well as every other rocketeer and engineer I've spoken with, has spoken out against the idea. First, the landing area is increased by 100 miles across, in addition to the rockets flight. And you can't be sure the rocket is going to go straight when you launch from altitude. How do you intend to keep the launch system vertical during ignition, how fast does the rocket need to go before the fins can provide stabilization to the rocket, what tracking system do you intend to use that can track above 60k MSL&Mach 2?

Do you intend to mix your own propellant and custom build the rocket, or buy an off the shelf solution?

Launching a balloon to 100,000 ft is easy, launching a rocket to 100,000 ft is far less so, and you need a rocket that can go roughly 100,000 ft MSL from sea level to reach space from 100,000 MSL.

From experience working a rockoon design for a large diameter rocket for an entire year, ditch the idea and have your club learn how to launch rockets first, learn electronics and staging second, and propellant manufacturing third.

There is a reason people don't do rockoons, and it's not because they're so cheap, easy, and effective.

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Well, if you or any other team is serious and legitimate enough about a rockoon to go through with such an operation. I potentially can provide a solution for the oceanic part of the equation. My family owns a vessel that is plenty large to both safely travel in the open ocean and with enough deck space to conduct a fairly major rockoon operation. It would be a two day trip to travel out the 100 miles from the nearest shore, conduct 12-16 ish hours of operations, and the return trip. I am fairly sure we could do it with just reimbursment for fuel, but I make no promises in either direction. Fuel costs for the two day trip is about 500 gallons of diesel so ~$2k depending on fuel prices. We currently have enough safety equipment and bunks for 4-5 possibly 6 people in addition to what is needed to run the boat.

A few caveats is you need to get tickets to fly up here to Alaska which are about $600 round trip per person as long as you plan far enough out in advanced. We have a few established routes to get commercial reloads up here if you want, similarly priced to what you get down where you are at. If you are doing EX for your motors we will just have to talk about the options.

So if there are any teams out there go ahead and send me a PM and we can start discussing it further. Considering the liability involved in this I have a pretty high expectation that you have a pretty solid idea on what you are doing. You don't have to have every detail ironed out at this point, but the first thing you tell me shouldn't be about how you plan on filling this large hydrogen balloon by hand. :eyeroll:

Xrain said:

Well, if you or any other team is serious and legitimate enough about a rockoon to go through with such an operation. I potentially can provide a solution for the oceanic part of the equation. My family owns a vessel that is plenty large to both safely travel in the open ocean and with enough deck space to conduct a fairly major rockoon operation. It would be a two day trip to travel out the 100 miles from the nearest shore, conduct 12-16 ish hours of operations, and the return trip. I am fairly sure we could do it with just reimbursment for fuel, but I make no promises in either direction. Fuel costs for the two day trip is about 500 gallons of diesel so ~$2k depending on fuel prices. We currently have enough safety equipment and bunks for 4-5 possibly 6 people in addition to what is needed to run the boat.

A few caveats is you need to get tickets to fly up here to Alaska which are about $600 round trip per person as long as you plan far enough out in advanced. We have a few established routes to get commercial reloads up here if you want, similarly priced to what you get down where you are at. If you are doing EX for your motors we will just have to talk about the options.

So if there are any teams out there go ahead and send me a PM and we can start discussing it further. Considering the liability involved in this I have a pretty high expectation that you have a pretty solid idea on what you are doing. You don't have to have every detail ironed out at this point, but the first thing you tell me shouldn't be about how you plan on filling this large hydrogen balloon by hand. :eyeroll:

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The current test motor is in the Q range, so there's no way to ship it up to Alaska, plus it'd have to be 100 miles+dispersion plot from space+FAA controlled airspace. Somewhere around 150-200 miles total to be sure you don't land in US airspace. That's in addition to the massive difficulty in launching a large rocket off a balloon, and the difficulty of building the hardware to carry it all into near space.

If you do a risk analysis on the systems required for each launch method, you'll find how much risk is added to hoist a rocket up that high.

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The large radius isn't for the balloon.

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edwinshap1 said:

The current test motor is in the Q range, so there's no way to ship it up to Alaska, plus it'd have to be 100 miles+dispersion plot from space+FAA controlled airspace. Somewhere around 150-200 miles total to be sure you don't land in US airspace. That's in addition to the massive difficulty in launching a large rocket off a balloon, and the difficulty of building the hardware to carry it all into near space.

If you do a risk analysis on the systems required for each launch method, you'll find how much risk is added to hoist a rocket up that high.

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There are ways to ship a Q motor up here, it would just take a bit more effort than the normal shipments. Generally we ship motors up here by barge, takes a few weeks but the costs are pretty low. Its always easier if the motor is split into grains (if you want to ship by air there is a 25lb limit per box of 1.3). But it is still more than possible to ship a full Q. We have definitely shipped much much larger motors than a Q up here made of much nastier things than APCP. If it really turns into a problem, I am also getting into EX motors so if someone wants to use some of my equipment I'd be willing to have a conversation about it. (especially if someone was willing to go halvsies with me on a paint shaker )

If you are 100 miles off shore in the gulf of Alaska away from major flight paths the FAA will more than likely be pretty open to working with you. So I don't think getting a class 3 waiver for it would be that tall of an order. Even then, I was already factoring 300 mile round trip, and extra 200 would make it a 3 day trip instead of two.

I am very much aware of the risks with rockoons, just if someone is going to go through all the hassle to do a rockoon I don't mind doing a bit to make it easier for you.

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saadzmirza said:

Hi Xrain,

I think the only way to find out for sure would be to contact the FAA.
What is the procedure for this?

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Unless the FAA has gotten stricter since then, to me, that makes a boat seem unnecessary for launch. Perhaps for recovery (if wanted).

I think looking into rocketry a bit more is a good plan for our club.
50 pounds isn't unbelievably light to aim for 200,000 feet for one reason. At 100,000 feet, barometric pressure is only 1% compared to sea level. This should mean negligible drag, for a much higher altitude. This is the whole principle of the rockoon.
What's "GSE"?

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All simulators will give you different results they use different assumptions in their models so they will give different feedback to you.

The Class III waivers are handled by the FAA Office of Commercial Space Transportation. You can certainty call them now, but personally I would wait until I at least had some level 2 HPR launches under my belt. Since you would be able to better answer the questions that they have for you. Honestly, It might also be a bit akward if they ask about your rocketry experience and you say the largest you have launched is a model rocket.

50 pounds is light because you have to include your GSE (Ground Support Equipment) into that number as well, so your 50 pound rocket is now 30 pounds or less. The lack of atmosphere definitely helps, but to hit the 300k ft. total that you want your rocket will roughly need to hit 100k ft. if it was launched on the ground.

As for what the HALO team did, I am not sure what they did to get authorization to launch like that. The best answer would be to see if you can get into contact with any of the team members and ask, since they have already done it before and none of us have. Could be because they used a hybrid rocket but I really cant tell you for sure.

Xrain said:

All simulators will give you different results they use different assumptions in their models so they will give different feedback to you.

The Class III waivers are handled by the FAA Office of Commercial Space Transportation. You can certainty call them now, but personally I would wait until I at least had some level 2 HPR launches under my belt. Since you would be able to better answer the questions that they have for you. Honestly, It might also be a bit akward if they ask about your rocketry experience and you say the largest you have launched is a model rocket.

50 pounds is light because you have to include your GSE (Ground Support Equipment) into that number as well, so your 50 pound rocket is now 30 pounds or less. The lack of atmosphere definitely helps, but to hit the 300k ft. total that you want your rocket will roughly need to hit 100k ft. if it was launched on the ground.

As for what the HALO team did, I am not sure what they did to get authorization to launch like that. The best answer would be to see if you can get into contact with any of the team members and ask, since they have already done it before and none of us have. Could be because they used a hybrid rocket but I really cant tell you for sure.

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To add to that, with 1% of the atmosphere you have 1% of the restorative effect the fins give, so any asymmetric thrust is going to throw the rocket wildly off course, especially when it's swaying in a sling under a huge balloon.

edwinshap1 said:

To add to that, with 1% of the atmosphere you have 1% of the restorative effect the fins give, so any asymmetric thrust is going to throw the rocket wildly off course, especially when it's swaying in a sling under a huge balloon.

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Very true, honestly I might not even put fins on the rocket at all. Just put a pretty fast rotation on it and rely on spin stabilization. Which might be tough to do since if you try to spin it with your launcher your launcher will want to spin faster than your rocket will. I suppose some weights on long poles might work, but again this is going to eat into your mass margin. And so goes the irresistible mass and expense inflation of rockets.

Though it might be cool to make a launcher with brushless motors in it to slowly spin the rocket up to speed during the balloon ascent. Might reduce the swaying at launch as well.

Regardless of your angular acceleration, newtons 3rd law is true. Half the angular momentum will rotate the base the opposite direction.

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You could get lvl1 fairly quickly and rather easily, if you so desire. Based on some of the many different ideas here, studying for the L2 could potentially save you a lot of heartache.

Presumably you're going to have tracking electronics, which means you have room for staging electronics as well. Otherwise if you CHAD stage APCP to BP, you won't be able to drag separate or have a boattail on the upper.

Of course if you're doing a cardbird this way, you can go test right now on the ground, and again at the next club flight near you.

CTI g65, by the way. Check out the initial thrust spike, and you'll have to spin it anyway so the moonie shouldn't be a bother.

Oh, and AAMV puts you back in EX territory, which it sounded like you would want to avoid per your intent to fly a Model Rocket.

saadzmirza said:

Using Hydrogen, (My group has access to free lifting gas due to a generous donation from the local welding company), ...

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Anyone else concerned with launching rockets near hydrogen? Hindenburg springs to mind

the sonic would definitely be EX, so you'd need to be 18 years old to secure your level 2 before you flew it. if you really want some height, look at the wildman blackhawk series as well.

grandcross said:

Anyone else concerned with launching rockets near hydrogen? Hindenburg springs to mind

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At 100kft AGL? Not particularly... I believe the intent is to launch close to when the balloon bursts. H2 needs a fairly small window of concentration for combustion as well. My guess is that there won't be enough oxygen mixed with the hydrogen to matter. And if it does burn, it's unlikely to hurt anything.

TRF. Where innocent dreams go to die.

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saadzmirza said:

Do you think an Apogee Aspire could withstand H impulse range? And does it have a payload section?

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Why not custom build it? You are already going to customize it for the payload.

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Are you launching this rocket from a rockoon still?