Double Negative 2020: A Black Rock High Altitude Project

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AndrewW

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So it has been a fairly long time since I have posted anything on this forum. I still do visit once in a while but since the app stopped being supported I found myself checking in only every other day or so. In addition to that I am considered an essential worker (Power Industry) in my area and find myself busier than ever. Coupled with the lack of launches I am finding it a bit more difficult than usual to get into rocketry at the moment. Due to lack of actual rocket related activity on the forum I am feeling that others may be feeling the same. My goal with this thread is inspire some and learn from others and that is it. This thread is by no means meant to take away from the seriousness of the Covid-19 Pandemic but rather to provide some distraction from it.

This is a team project and we all generally maintain a very low online profile preferring to interact more in person than via keyboard. But in light of the current situation we are feeling really disconnected from the rocketry community as a whole. This is why we have decided to share this project online.

I just want to make a point up front that this is a team project and although we all have a decent amount of experience, the decisions and choices we have made are ours and ours alone. This may not be the way everyone chooses to build a project like this but this is what we have come up with so far. Our overriding set of criteria to date has been Safety, Reliability and Mission Success and in that order. If one of those three cannot be fulfilled then it is back to the drawing board to figure a better way.

This will not be a typical build thread as over 9 months have already been invested in the project. It will be more of a recap to date followed by a continuation of the build. In the following days and weeks I hope to introduce myself and the team as well as document some of the unique challenges we have encountered so far.

Some basic information regarding the project:
  • Air frame: 4” to 3” MD Two Stage FG Airframe w/FG and CF Fins
  • Booster Propulsion: N Class EX (Bates Grain)
  • Sustainer Propulsion: M Class EX (D Grain)
  • Team Members: 5
  • Expected Altitude: 100k +
  • Expected Velocity: M2.8 +
I hope you all enjoy the build and the eventual launch Please feel free to ask any questions you have either on the forum or via PM.

Double Negative Cropped Text.png
 

mbeels

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Awesome, I'll be following along closely!
 

AndrewW

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So this project really started as an extension of some off the things a few of us on the team have been currently working on. Mostly High Power Two Stage flights and EX motors. We started working on a couple of projects in the past year or so which involved flying larger EX powered two stage rockets on the East Coast. This really illustrated to us the efficiency of the two stage concept as it was at sometimes a challenge to develop a motor combination that provided sufficient thrust off the pad and stay safely below the waivers even with a modest sustainer motor. This eventually led to discussions of a larger and higher performance project to be flown out west. So we started to kick around some ideas and did a ton of research and eventually settled on a 4 fin 4" to 3" two stage design. We came up with a set of criteria early on that would help guide and define many of the choices we have made so far. These are as follows:
  1. Safety-This is not to be compromised! Several of us work in mission critical and hazardous industries that are completely intolerant of mistakes so this is something we live with a practice every day. If we cannot find a safe way of doing something it doesn't get done, it as simple as a that!
  2. See number 1, again there is nothing about this hobby or project that is worth putting any of us or anyone else for that matter in harms way!
  3. Reliability - This is by no means an optimized design. We are investing a lot in this project and with soooo many things that can potentially go wrong we have tried to make most of our design choices with a bias towards reliability versus all out performance. This means designing with strength, redundancy, testing and good engineering practice in mind.
  4. Use of Known Technology- Nothing about this design is new or ground breaking. Again with reliability in mind we have tried to utilize as many proven products and design concepts as possible. It is the hope that what we learn from this project if successful will lead to a more optimized performance oriented design in the future.
  5. Have Fun - Again this is a hobby, with something as complex as this project there is much greater probability of failure. We are all trying to maintain the perspective that this is more about the build, learning and getting the opportunity to go to an amazing place and have an adventure along the way.
So I will get into more of the design choices and where we are currently at in the build in later threads but here are a couple of screen shots of the RasAero and OR files. The design is still not completely finalized as some of the final weights and dimensions will likely change slightly as we complete certain segments of the air frame and motors.

RasAero Screen Shot.png


Open Rocket Screen Shot.png
 

mikec

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Having been involved in three similar projects, none successful, I'll be very interested in two aspects of your design: the interstage coupler, and what kind of dual deploy you are using in each stage. Looks to me like you are not using conventional two-break dual deploy, which is fine, but means you should have lots of experience with whatever mode you are using before trying something on this scale.

Best of luck, not trying to be a downer, just offering some hard-won advice.
 

tfish

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Andrew, Would you like some ... technical info, advise, insider info, help? If so all they would ask is for is credit if you use any of their ideas.

Tony
 

AndrewW

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Andrew, Would you like some ... technical info, advise, insider info, help? If so all they would ask is for is credit if you use any of their ideas.

Tony
We would absolutely like any technical info, advise, etc... For most of us this is all about learning. I don't think any of us are caught up in trying to prove something or seeking glory and adoration from others. As stated earlier we are looking to learn from others as much as possible to help give us the greatest possible shot for success. I have no problem giving credit where credit is due and personally look forward to discussing this project with others. For me this hobby has always been about learning and the great people I have met along the way.

For me personally Tony I have learned a lot from your posts and videos over the years and I would just like to thank you for your contributions to the hobby. Part of what you have done gives me the inspiration to start a project like this in the first place.

Andrew
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AndrewW

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Having been involved in three similar projects, none successful, I'll be very interested in two aspects of your design: the interstage coupler, and what kind of dual deploy you are using in each stage. Looks to me like you are not using conventional two-break dual deploy, which is fine, but means you should have lots of experience with whatever mode you are using before trying something on this scale.

Best of luck, not trying to be a downer, just offering some hard-won advice.
No problem you are not being a downer. It is thinking like that, that led to the name Double Negative. In my line of work you need to approach every problem and system with a mindset of "what can possibly go wrong." This has led to me being judged by others as generally having a negative attitude. But when dealing with critical systems with a lot on the line I feel like this is an asset versus a detriment. So I liked the idea of a lot of negative criticism leading to a positive result hence the name Double Negative. I will go into more detail regarding the ISC and deployment schemes in later posts and by all means feel free to comment.

Andrew
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tfish

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Andrew,
Copy and thanks for the kind words. I try to pass along things I've learned (usually the hard way) so others don't have to also.

I've seen, both young and older groups, try to reinvent the wheel, let alone keeping the wheels on.

I am/was not a listed member of this group but I did help out with some minor things.

hopefully you've not already seen this... https://cdn.hackaday.io/files/22132946895488/AeroPac 2012 100k' Program Report.compressed.pdf

Seems very similar to your project..less the Research motors. All those involved in this project were very experienced Rocketeers.

Tony
 

HVArcas

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Yeah this looks like an aeropac 100k clone, definitely curious for more detail on the interstage and motors
 

AndrewW

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Yeah this looks like an aeropac 100k clone, definitely curious for more detail on the interstage and motors
This project does indeed have a lot in common with the Aeropac project but the initial concept came about with no actual knowledge of their accomplishment. The project had more inspiration from the Loki Dart and what we felt comfortable with then trying to mimic an existing design. That being said shortly after discussing the 3" to 4" idea I came across the Aeropac project and for us it just further validated the concept and helped solidify our choice. We initially settled on the 3" to 4" idea for several reasons. First being it was in the range of motors we felt comfortable making and flying. It also provided just enough room for electronics and recovery gear. Additionally cost, availability and machining capabilities played a significant role in the choice as well.

As Stated in one of my previous post we have been trying to learn as much as possible in order give us a decent chance of success. To this point we have scoured the web researching other high power and amateur rocketry projects as well as reading hundreds of pages of NASA documents. There was definitely a lot to be learned from the Aeropac flight. We discussed many of the things that worked for them as well as what appeared to give them some difficulty. There are several things we decided to do differently from the Aeropac team. We spent a lot of time focusing on stability and trajectory. The Aeropac flight had a significant horizontal component to it which definitely had an impact on their ultimate altitude. Up front we decided to go with a 20' launch tower versus rail buttons with the hope that we can begin the flight as vertical as possible. Secondly we decided to go with a four fin design for several reasons. One being stability and another being a shorter span and less probability of fin flutter. Our motor design criteria was more or less based on existing two stage knowledge with a high thrust booster followed by a long burn sustainer. The Aeropac project trended more towards a long burn booster and sustainer which has its merits but unless you start the flight with very little to no horizontal component you may find yourself a lot lower and farther away than you expected. Lastly we will be using an aluminum ISC which I will spend more time going over in a future post.

I hope everyone is enjoying their Memorial Day Weekend and that it is as beautiful as it is up here in the North East.

Andrew
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mikec

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Yeah this looks like an aeropac 100k clone...
I believe I read, though I can't recall where, that after its first successful 100K flight, the Aeropac design had at least one flight where the second stage went unstable. I always thought their fins were a bit too small. The design on this thread looks like it has a lot more margin.
 

HVArcas

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I believe I read, though I can't recall where, that after its first successful 100K flight, the Aeropac design had at least one flight where the second stage went unstable. I always thought their fins were a bit too small. The design on this thread looks like it has a lot more margin.
Kinda.

Their original design is in a museum. They rebuilt with a commercial fin can and lost a ton of altitude, and ever since have been tinkering. Their emphasis has been on reproducible and repeatable results rather than pure altitude. Remember, these are also the folks that fly six inch student payloads to 10k with an absurd success rate, so it is not much of a stretch to imagine similar goals for the 100k project
 

JimJarvis50

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Kinda.

Their original design is in a museum. They rebuilt with a commercial fin can and lost a ton of altitude, and ever since have been tinkering. Their emphasis has been on reproducible and repeatable results rather than pure altitude. Remember, these are also the folks that fly six inch student payloads to 10k with an absurd success rate, so it is not much of a stretch to imagine similar goals for the 100k project
I have tried for 100K nine times to date and got there five times. Of the four that didn't get there, two were sustainer motors not lighting and two were shreds after sustainer burnout. I'm not sure if that's good or bad, but I don't think I've ever posted the statistics.

I had a couple of interesting 4x3 flights, both N2500 to M650 (to stay in the "N" range for total impulse). As it turns out, the rocket with those motors was capable of about 75K. The first time, prior to RasAero, was at Argonia, where I expected about 45K based on Rocksim. Just to be safe, I programmed the flight to deploy the drogue if the rocket was still going up at 45K. Unfortunately, this is what happened, but the rocket was still going in excess of Mach 1. The second was at Black Rock. The flight reached 74K but landed on a mountain. It was an interesting recovery.

Good luck on the project. Two-stagers are fun.

Jim

Oops, 10 tries. The one I missed was, um, not a good flight.
 
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tfish

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Sounds like you guys are doing your homework..

Now that you have Jim Jarvis attention that will be a big help too!

Tony
 

tfish

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Since I brought up AeroPac....

There have actually been 2 (100K) group projects. The first time was in 2009...even more old school stuff.


Tony
 

AndrewW

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Good luck on the project. Two-stagers are fun.

Jim

Oops, 10 tries. The one I missed was, um, not a good flight.

Thank you so much for chiming in Jim!

Honestly you do not make it very far down the extreme HP two stage road without coming across your name. I have been following your accomplishments and exploits for several years now and it would be a real honor to have any input from someone with your experience. I have also read both of your papers regarding CF construction techniques with interest. In fact both of them reside in a binder in my shop as a reference.

Ironically I just finished the last pages of Mark Canepa's unbelievably descriptive and entertaining book "Large and Dangerous Rocket Ships" which features some of your projects quite a bit in the epilogue. If you are a true fan of High Power Rocketry you have to take the time to read this to really appreciate the hobby and the hardships and accomplishments of the many that made it what it is today.

1590540102218.png

I very much look forward to your input and hope to meet you in person some day (hopefully this fall but I am starting to worry this may not happen this year due to things well beyond our control)

I have been away from home for the past few days as I have taken the family up to our house in the mountains for the holiday weekend. In the next day or two I will post some more information about the ISC as there seems to be some interest in that specifically.

Andrew
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OverTheTop

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Nice, ambitious project. I hope it goes well for you.

FYI I did my first two-stage flight last year. O3400 to M2020. Was not MD or particularly optimised but got a respectable 37500'. Feel free to peruse my build and ask any questions you might have.
htps://forum.ausrocketry.com/viewtopic.php?f=6&t=5019
 

JimJarvis50

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Thanks Andrew. I read the book as well and would also recommend it to anyone interested in learning about how the hobby developed. It was particularly interesting for me as I know many of the people that were discussed, but did not know all of their contributions.

I'll keep an eye on your project and chime in if I have an opinion. Here are a couple of early thoughts....

The use of research motors will make the project more difficult because the timing and characteristics of the booster motor will be less well defined. I generally define the flight profile from time of launch rather than from time of burnout. Then, the booster motor can do whatever it wants, within limits, without affecting the flight timing.

For flights over 100K, the electronics programming is packed with compromises. If you can afford the $ and weight budget, Kate II makes that part of the project much easier. Fiberglass tubes make it easier to use Kate.

If you want to use black powder for deployment, you need to account for the altitude. But, it is easy to do and you are not required to use CO2. I have an article on this that I've posted several times that shows the approach I use.

Jim
 

BDB

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"So this project really started as an extension of some off the things a few of us on the team have been currently working on...flying larger EX powered two stage rockets on the East Coast."

It's great to see teams developing ambitious projects like this on the East Coast. Hopefully, I'll get to join those ranks someday. In the meantime...I'm going to live vicariously through this thread.
 

HVArcas

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I have tried for 100K nine times to date and got there five times. Of the four that didn't get there, two were sustainer motors not lighting and two were shreds after sustainer burnout. I'm not sure if that's good or bad, but I don't think I've ever posted the statistics.

I had a couple of interesting 4x3 flights, both N2500 to M650 (to stay in the "N" range for total impulse). As it turns out, the rocket with those motors was capable of about 75K. The first time, prior to RasAero, was at Argonia, where I expected about 45K based on Rocksim. Just to be safe, I programmed the flight to deploy the drogue if the rocket was still going up at 45K. Unfortunately, this is what happened, but the rocket was still going in excess of Mach 1. The second was at Black Rock. The flight reached 74K but landed on a mountain. It was an interesting recovery.

Good luck on the project. Two-stagers are fun.

Jim

Oops, 10 tries. The one I missed was, um, not a good flight.
Oh hey, thanks! I know more than a few folks that were curious about that success rate; sort of speculated close to what you posted but way better to have the real deal
 

AndrewW

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So I will get started with discussing some of the components of the project we have decided on so far with some of the specifics regarding the ISC (Inter Stage Coupler).

For anyone involved in HP 2 stage projects this is an area that gets particular attention as it is one of the areas more prone to failure. As we are trying to design around reliability and safety we decided to go with an all aluminum ISC. This decision was made based on strength, cost and machining capabilities. Here are some pictures of the conceptual drawings as well as the finished design.

A lot of thought went into this design and I will discuss more about the fabrication and details in later posts. We are making all the motor hardware ourselves so this gave us some addition flexibility in how we designed the ISC/sustainer motor interface. More specifically we were able to incorporate a tail cone that fits nicely into the ISC which acts as a bearing surface as well as provides alignment. It has the additional benefit of breaking free fairly easily. The air frame tube will also nest within the first 0.75" of the ISC but will only be used for axial alignment and not be under any thrust forces. Another factor considered in the design is the ability to adjust the fit in the field as the conditions we will encounter out at Black Rock will surely differ from my shop.

Andrew
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Inter Stage Coupler V1.PNG
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AndrewW

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Nice, ambitious project. I hope it goes well for you.

FYI I did my first two-stage flight last year. O3400 to M2020. Was not MD or particularly optimised but got a respectable 37500'. Feel free to peruse my build and ask any questions you might have.
htps://forum.ausrocketry.com/viewtopic.php?f=6&t=5019
Hey thanks for the link OTT! I just ran through all 8 pages of your build thread and I must say you really did an amazing job. There is definitely a lot to digest in there and I am sure there is plenty for me to learn from it and I will definitely spend some more time going through it. I am sure I will have questions and I truly do appreciate and feedback or input you may have on our project.

Andrew
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AndrewW

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"So this project really started as an extension of some off the things a few of us on the team have been currently working on...flying larger EX powered two stage rockets on the East Coast."

It's great to see teams developing ambitious projects like this on the East Coast. Hopefully, I'll get to join those ranks someday. In the meantime...I'm going to live vicariously through this thread.
 

AndrewW

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The team aspect of this has been one of things I most value about this project. I feel very few people really understand the rocketry hobby including most of my close friends and family. To have the opportunity to work with others as passionate and excited as I am about this stuff has been extremely rewarding. A project like this would be difficult at best if taken on by a single individual and I feel that this is definitely a situation where whole team is greater than the sum of is parts.

I hope you enjoy the journey and it inspires you to begin your own.

Andrew
 

mikec

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So I will get started with discussing some of the components of the project we have decided on so far with some of the specifics regarding the ISC (Inter Stage Coupler).
Wow. Parallel development. Below is the ISC from my 3" to 54mm project. Very similar, right down to the tailcone!

My original version of this was made out of Delrin but that proved a bad choice and snapped in half at BALLS last year. Current version is aluminum like yours.

isc.png
 

Blast it Tom!

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Here's another "essential worker" in the power generation industry subscribed! Though I don't know if I'll ever get anywhere near a project like this, it's very interesting reading! (We haven't even launched our Odd'l "Birdie" yet!)
 

AndrewW

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Wow. Parallel development. Below is the ISC from my 3" to 54mm project. Very similar, right down to the tailcone!

My original version of this was made out of Delrin but that proved a bad choice and snapped in half at BALLS last year. Current version is aluminum like yours.

View attachment 418582
Hey that looks great! I like that we both came up with a similar idea independently. In some ways it feels like it validates the design choice a bit.

In your set up will the tailcone be the load bearing surface?

Andrew
 

mikec

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In your set up will the tailcone be the load bearing surface?
Yes. The whole tailcone sits in the matching receptacle in the ISC. I flew the Delrin version once on a test flight (K1000 to J240), then it failed at BALLS (M1590 to L265), then I flew the aluminum version once (K1000 to J210). So 2 out of 3 for the ISC.

It's always tricky to get it to fit not too tight, not too loose. I think it was not seated quite right at BALLS and the off-axis loads are what broke the Delrin.
 
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