O-Engine Altitude Questions for High School Rocket Club

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Nick@JET said:
This is truly ambitious and I commend you for your big dream. Being an L3 myself recently I wouldn't even think this would be feasible for me, my budget and lack of knowledge without taking steps first. Not poking on your dream - that's what I like about Rocketry community - most people here want you to win. But from their perspective they want you to do it without hurting anyone or anything and bruising rocketry as a whole so keep that in mind when you read these replies. If your taking stupid risks - your mentor can steer and guide you.

Obviously you are a smart person and have thought a lot about it. So let the replies refine your path.

I don't think this is wise or doable without an L3 TRA / NAR mentor with you by your side, that's where it starts. Post this and people will start to take this more seriously and you will likely get more specific advice.

Good luck with your endeavor - honestly I wish I was that young when I started
Click to expand...

Thanks for the good luck. I can assure you we won't be taking stupid risks, and I am typically pretty over-ambitious, but I will work with our mentor (not sure on his cert. level but he works for NASA) on scaling it down and avoiding risks. That's the main reason we have received funding, aerospace is becoming so competitive, it's a daunting task even when we start at 14.

-Jack
 
RocketFeller said:
We aren't a high school, but we have had a rocketry program in place at our K-8 school - Silver Crest School, located in rural Oregon - for seventeen years.

We normally launch LPR rockets in our sports field, but we have done a couple HPR projects over the years. Our first project was an all fiberglass rocket with a 54mm motor mount. We never flew it on more than an 'I' motor, as I was only level 1 certified and I was the only mentor.

Last year we decided to take on a much more ambitious project (although still far short of your intentions), a 12.75" upscale of the Binder Design Dragonfly. The rocket is all carbon fiber and balsa composite and weighs in at ~40 pounds. Our first launch was on a research K3800, our second launch was on an L850W. Our next launch will been an L1590T, followed by a Sparky research 'N'.

This project would never have happened without the guidance of some very experienced rocketeers. Of our three mentors, I am the least experienced. I have been flying HPR since 1999/2000 and am currently L2. My role was to help with the design and fabrication of the rocket. I was present during every step taken. Mike Fisher of Binder Design/Max Q/Fisher Research has been our advisor in regards to motors and built the K3800 for us. He will also be building the sparky 'N' for us. Our third mentor, Gary K., is a retired aerospace engineer, an L3, and a club RSO. He supervised the final assembly and helped us with our simulations.

I don't mean to be discouraging you - we built an "L3" rocket that many people thought would leave its fins fluttering in the breeze as it launched, and we did it with a team of six middle-school girls. I do, however, want to emphasize that the entire process was done with the close attention of several experienced adult mentors. We are currently in the planning stages of our next project, a minimum diameter 98mm 'O' rocket. If our plan comes to fruition it will mean a trip to the Black Rock Desert, several thousand dollars in fundraising, and help from a lot of experts....

Best of luck to you, I will be following this project with interest!
Click to expand...

Dan,

And I thought we were a little young. That's very impressive I applaud you taking complex STEM concepts to students so young. The longevity of your program is very impressive and congratulations on the successful upscale of the dragonfly. How did you guys fund these projects? Our mentor, I won't name him here without his permission, launched a rocket to 50 miles up back in the 90's and has been sequestered by NASA working with advanced propulsion for the last year. He will not be able to be as involved as you and the other mentors have been for your club, but he will be there as often as he can, and his enormous experience could not be more valuable to us. Good luck with your 98 mm!

-Jack
 
jcamhale said:
That was Tesla STEM. If I remember correctly they worked with Aerojet Rocketdyne on that project. I would have like to have seen it launch.

In regards to this O motor project it seems a little too ambitious for a high school to take on. The university that I go to has built up to an Ex N motor for IREC. We are lucky that our technical advisor was willing to help us learn everything.There is just so much stuff that you need to know about working with EX motors that is above high school level. Personally I think you are going to run into costs that you don't expect. I'm not sure what propellant you're planning on using, but it needs to be characterized in at least a 54mm motor and for more accuracy it should be characterized in a larger sized motor (as close to the actual flight motor as possible). All of that adds up quickly. Cost aside the logistics are insane for large projects like that. I would start smaller and work up to the O project.
Click to expand...

Cameron,

Thanks, just answered my question to Nytrunner.

Thank you for your input. I don't want to go into too much detail on the engine and risk getting the thread deleted, but it will be a high solids APCP engine 3.7" of usable room in the chamber because of the phenolic insulation. I'm sure we will run into extra costs, but as far as the engineering of the actual engine, we have the appropriate funding, and we have launch site, equipment, waiver, and insurance all figured out. We have a solid $250 of room in the budget for smaller tools and equipment. We'll be characterizing by burning two full-size grains inside of a 4.5" tube with insulation. Logistics are major, but I think we have the capacity.

-Jack
 
Here's one of their tests.

[video=youtube;FE_yuSgKo20]https://www.youtube.com/watch?v=FE_yuSgKo20[/video]

@jcam; since you're from WV, its highly likely we spoke at the river gathering after competition.
 
jcamhale said:
That was Tesla STEM. If I remember correctly they worked with Aerojet Rocketdyne on that project. I would have like to have seen it launch.

In regards to this O motor project it seems a little too ambitious for a high school to take on. The university that I go to has built up to an Ex N motor for IREC. We are lucky that our technical advisor was willing to help us learn everything.There is just so much stuff that you need to know about working with EX motors that is above high school level. Personally I think you are going to run into costs that you don't expect. I'm not sure what propellant you're planning on using, but it needs to be characterized in at least a 54mm motor and for more accuracy it should be characterized in a larger sized motor (as close to the actual flight motor as possible). All of that adds up quickly. Cost aside the logistics are insane for large projects like that. I would start smaller and work up to the O project.
Click to expand...

Cameron,

Thanks, just answered my question to Nytrunner.

Thank you for your input. I don't want to go into too much detail on the engine and risk getting the thread deleted, but it will be a high solids APCP engine 3.7" of usable room in the chamber because of the phenolic insulation. I'm sure we will run into extra costs, but as far as the engineering of the actual engine, we have the appropriate funding, and we have launch site, equipment, waiver, and insurance all figured out. We have a solid $250 of room in the budget for smaller tools and equipment. We'll be characterizing by burning two full-size grains inside of a 4.5" tube with insulation. Logistics are major, but I think we have the capacity.

-Jack
 
Nytrunner said:
@jcam; since you're from WV, its highly likely we spoke at the river gathering after competition.
Click to expand...

Possibly. I was only down at the river for a couple of hours that night. If you talked with anyone from WVU it was more than likely some of the other guys that stayed longer.
 
terryg said:
Doing anything with Zinc Sulfur is taking a stupid risk.
Click to expand...

I think the young guy has been thoroughly warned by the forum community about the dangers.
Their project falls outside of the general hobby safety codes, and it sounds like they are pursuing non-club routes for completing their mission.

Belittling attitudes won't make them abandon their goal.
 
terryg said:
Doing anything with Zinc Sulfur is taking a stupid risk.
Click to expand...

Terry,

Like I already said; ZS is not my propellant of choice, but it will not cost the club anything and we have launched these small ZS engines many times without fail under the supervision of our mentor who is over-qualified like you wouldn't believe.

-Jack
 
Nytrunner said:
I think the young guy has been thoroughly warned by the forum community about the dangers.
Their project falls outside of the general hobby safety codes, and it sounds like they are pursuing non-club routes for completing their mission.

Belittling attitudes won't make them abandon their goal.
Click to expand...

I appreciate it Nytrunner.

-Jack
 
JackO said:
Of course, bad habit of over-using the #1 priority expression. Our number one priority is always safety. Our top preference for the construction of the engine is reliability so it does not CATO thereby promoting safety.
Click to expand...

JackO:

Not wanting to pile on, but if you are at all concerned about safety, don't even think of messing with ZnS. There's a bunch of good reasons why micrograin propellants aren't allowed by Tripoli. Not the least of which is that they tend to explode when compressed (made)
 
JackO said:
Dan,

And I thought we were a little young. That's very impressive I applaud you taking complex STEM concepts to students so young. The longevity of your program is very impressive and congratulations on the successful upscale of the dragonfly. How did you guys fund these projects? Our mentor, I won't name him here without his permission, launched a rocket to 50 miles up back in the 90's and has been sequestered by NASA working with advanced propulsion for the last year. He will not be able to be as involved as you and the other mentors have been for your club, but he will be there as often as he can, and his enormous experience could not be more valuable to us. Good luck with your 98 mm!

-Jack
Click to expand...

Thanks, Jack!

We did a gofundme drive that raised about $1300. We also received a $500 STEM grant from a major aerospace company. I spent a few hundred dollars of my own money. That money covered electronics, recovery gear, Aeropoxy, and the nosecone.

The majority of our components (CF airframe, Cf centering rings, CF fin skins, balsa core material, Nomex material) were donated by the manufacturers. Our EX motor was donated by Fisher Research. The cost of these materials would have far exceeded our budget - I would recommend contacting local suppliers whenever possible to beg support. For example, there may be a local fabrication business that could help with your fin can construction.

I have read a few posts that speak to your use of zinc sulfur. I don't know much about formulating propellants, but enough people have raised concerns that you may want to reconsider. In a project of this scale, saving a few hundred dollars in propellant ingredients is not going to make that much difference in the overall expenditure. Using an inferior/unsafe formula because it is free makes very little sense to me....
 
cbrarick said:
JackO:

Not wanting to pile on, but if you are at all concerned about safety, don't even think of messing with ZnS. There's a bunch of good reasons why micrograin propellants aren't allowed by Tripoli. Not the least of which is that they tend to explode when compressed (made)
Click to expand...

There are a number of safety risks during processing that are not present with AP and other binder based propellants. Jack, can you elaborate on the safety protocols and handling procedures you have in place? What specific steps have you put in place for risk mitigation during processing? Do you have the proper PPE in place and are the people processing propellant trained in the proper procedures? What disaster response plans do you have in place?

I am not trying to discourage you with this post. I want to see you succeed. But, I also want you to be safe. I would ask these questions of anyone regardless of the propellant type being processed and have answered them myself for my own personal operation. PLEASE take the time to answer these questions and get everything in order before attempting anything. If your mentor is as qualified as you say he is, he can help you get this all defined. I and many others on here are specifically concerned with the process of compressing the propellant and making sure it's done in a way that if a mishap does happen (and the risk of mishap is high enough for micrograin propellants to give people serious pause) people are protected from danger.

Also, if you are going to be switching to AP propellants for the actual attempt, I don't think you'll save too much on cost. You will need different equipment to process a binder based AP propellant and buying 2 sets of equipment will likely nullify cost savings from the free ZnS materials. You will also likely need a much more elaborate setup for safety with ZnS. Not to mention the fact that you would need to develop 2 sets of procedures and safety proctocols. I think the increased experience your team would gain from building a bunch of smaller AP engines would be invaluable to you when building your larger test fires.

Fly high and push on. Go for it. As you have specific questions, post them here and we'll do our best to give you some meaningful answers.
 
We're talking an O-motor here.
Maybe 40 pounds of propellant.
At $10/pound, which is high, that's $400.

The risk associated with micro-grain propellant is not worth the attempted $400 savings.
I don't care who your mentor is - abandon all use of zinc-sulfur.
Start with and stick with AP.
 
Personally I would be spending the little extra money and using commercial motors. MUCH safer, probably better chance of success, and it could be done as part of your Tripoli membership with full insurance coverage and lots of support :wink:

A large ZS motor scares me. This is a hobby where the energy scales logarithmically as you progress, so the difference in energy as you go from smaller rockets to larger ones can seem to be a less of a problem that it really is. As an example, if you double-size a motor, it ends up with eight times the energy. You look at it and think "only twice as much, so it should scale without problems" but there is actually much more energy available. Some of the burn processes are non-linear and don't scale in a way our linear brains prefer either (unless you know the mathematics behind it).

Have fun and stay safe.
 
The way I see it, there's 3 goals here:

1. Build an L3/high speed capable rocket

2. Hit 50000 feet with a rocket.

3. Build an O size EX motor.

These are all admirable goals on their own. Personally, I haven't done any of them.

So to the OP as a thought experiment. If you were forced to drop one of these 3 goals- which one would you drop and why? Do you really need to do all three at once? What exactly are you trying to prove? Would you feel like you failed if you got only one item done but not the other two?
 
cbrarick said:
JackO:

Not wanting to pile on, but if you are at all concerned about safety, don't even think of messing with ZnS. There's a bunch of good reasons why micrograin propellants aren't allowed by Tripoli. Not the least of which is that they tend to explode when compressed (made)
Click to expand...

I am not very familiar with ZnS in all honesty, but we'll be launching on the site of and under the supervision of the Reaction Research Society, they have model rocketry experience spanning 5 decades. And they use ZnS often for student projects. I will talk to our mentor about its properties.
-Jack
 
RocketFeller said:
Thanks, Jack!

We did a gofundme drive that raised about $1300. We also received a $500 STEM grant from a major aerospace company. I spent a few hundred dollars of my own money. That money covered electronics, recovery gear, Aeropoxy, and the nosecone.

The majority of our components (CF airframe, Cf centering rings, CF fin skins, balsa core material, Nomex material) were donated by the manufacturers. Our EX motor was donated by Fisher Research. The cost of these materials would have far exceeded our budget - I would recommend contacting local suppliers whenever possible to beg support. For example, there may be a local fabrication business that could help with your fin can construction.

I have read a few posts that speak to your use of zinc sulfur. I don't know much about formulating propellants, but enough people have raised concerns that you may want to reconsider. In a project of this scale, saving a few hundred dollars in propellant ingredients is not going to make that much difference in the overall expenditure. Using an inferior/unsafe formula because it is free makes very little sense to me....
Click to expand...

Dan,

That's great in regards to the fundraising, congratulations. I used GoFundMe for my Eagle Scout Project and reached my goal in two days. I'll be following a similar path if our club goes over-budget. I'm surprised that those type of donations are so accessible. Our mentor and a contact of mine know many of the people in high power community, so if we're in need of some parts, I'll be sure to beg. Like I said before, I'll be talking to my mentor on the subject. To supply some details, in the past our club made 6 ZnS rockets which would have to be redesigned probably in full for APCP, so it s more than just the cost of the propellant. And these ZnS rockets have been very reliable in the past, of so I have been told. I do appreciate everyone's concern, I will make sure the method is safe and minimize risk.

-Jack
 
Nate, Fred, and OvertheTop,
I will talk with my mentor and get back to you. I cannot say the same thing too many times. I appreciate all of the concern, and I will draft a meaningful response next week.

-Jack
 
OverTheTop said:
Personally I would be spending the little extra money and using commercial motors. MUCH safer, probably better chance of success, and it could be done as part of your Tripoli membership with full insurance coverage and lots of support :wink:

A large ZS motor scares me. This is a hobby where the energy scales logarithmically as you progress, so the difference in energy as you go from smaller rockets to larger ones can seem to be a less of a problem that it really is. As an example, if you double-size a motor, it ends up with eight times the energy. You look at it and think "only twice as much, so it should scale without problems" but there is actually much more energy available. Some of the burn processes are non-linear and don't scale in a way our linear brains prefer either (unless you know the mathematics behind it).

Have fun and stay safe.
Click to expand...

Doesn't ZnS have a much lower ISP than APCP ?

They may look cool in pictures but I think they are less efficient, not to mention the risk associated.
From various sources online:

"Zinc–sulfur (ZS) propellants-Composed of powdered zinc metal and powdered sulfur (oxidizer), ZS or "micrograin" is another pressed propellant that does not find any practical application outside specialized amateur rocketry circles due to its poor performance (as most ZS burns outside the combustion chamber) and fast linear burn rates on the order of 2*m/s. ZS is most often employed as a novelty propellant as the rocket accelerates extremely quickly leaving a spectacular large orange fireball behind it."

Zinc-Sulfur
In the early days of experimental rocketry powdered zinc and sulfur were a common propellant.*This was also referred as "micrograin." Its burn rate depends on how small the particle size is for each and how much it is compressed.* The more dense it is compacted, the slower the burn rate.* It's burn rate is between 14 and 290 inches per second.
* from "How to Make Amateur Rockets", John H. Wickman, 2nd Ed, pg 3-3

Because it is so difficult to compress the powder to a known value consistently, rocket motors made with this formula typically either don't have much power and may not get off the launch pad, or they blow up from over pressurization.* It is not used by any serious rocketeers today.
 
Last edited:
Forgot where I saw it, but a picture & description of the zns process had it being made with a large earthen berm all the way around it, people in helmets and chest protectors. If my memory serves, a compresser, a person who does loading, a supervisor and a safety person.
 
cbrarick said:
Forgot where I saw it, but a picture & description of the zns process had it being made with a large earthen berm all the way around it, people in helmets and chest protectors. If my memory serves, a compresser, a person who does loading, a supervisor and a safety person.
Click to expand...


I recall seeing the same diagrams.
Probably this manual, I have it somewhere in my old rocketry stuff :
"US Army Ft Sill Guide Amateur Rocketry: Zinc-Sulfur Rocket Motor Design & Test"
ft-sill-cover.jpg

Any interest in exotic propellants like ZnS quickly went away after reading that.
Hats off to Homer Hickam and Quentin though...
 
I think that's it. I was all in to do some ZnS because it looked so cool, but then I read about it there and bailed! Glad I never bought the Sulfur, wouldn't know what to do with it now.
 

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