Double Negative 2020: A Black Rock High Altitude Project

[AndrewW]

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.

I tried to consider the ability to adjust fit into the design. It is part of why I went with the tapered seat in the first place. The last thing I want to be doing out at Black Rock is messing with a poorly fitted ISC.

 

[mikec]

The last thing I want to be doing out at Black Rock is messing with a poorly fitted ISC.

Agreed, definitely. But time runs really fast in the runup to a big launch, so make sure to do as much prep and fit checking as you can long in advance. And then things may not go quite to plan at the pad, especially since this may be the first time you have igniters in place, etc. On that topic, how does your ignition work? Mine just has a wire conduit down the side, into a channel in the ISC, and then up into the motor.

 

[AndrewW]

Agreed, definitely. But time runs really fast in the runup to a big launch, so make sure to do as much prep and fit checking as you can long in advance. And then things may not go quite to plan at the pad, especially since this may be the first time you have igniters in place, etc. On that topic, how does your ignition work? Mine just has a wire conduit down the side, into a channel in the ISC, and then up into the motor.

Having as much prepared as possible before hand is another key concept we have tried to take into account in each step of the design. For me personally I have always been amazed but how it still seems to take 4 hours to ready a near fully prepped complex or 2 stage rocket. I definitely don't want the pressure of worrying about time ticking away so a lot of thought has gone into field prep and assembly at the pad. These are all things that will be practiced and check-listed.

Ignition is an interesting topic and has probably had more thought go into it than any other aspect of this project. I will go into it much greater detail later but the basics are that we will be using a HEI system fully within the sustainer utilizing a commercial aerospace initiator. Additionally the electronics, safe/arm system and procedures have been designed with a lot of input from NASA papers as well as decades of working around dangerous and mission critical systems.

 

[mikec]

the basics are that we will be using a HEI system fully within the sustainer utilizing a commercial aerospace initiator.

Looking forward to the details. My two cents: 1) HEI solves one set of problems and replaces them with another set. I've worked on projects that used HEI and not been happy with the results. A commercial tested solution would be great. 2) Whatever seems safe enough to you may not pass muster with everyone that has to sign off for a 50K+ flight at BALLS, and I'm not sure what will be judged acceptable for HEI going forward.

 

[AndrewW]

Another issue we worried about at the ISC was the possibility of galling between the motor case and the inside wall of the coupling. This partially led to the tapered seat design as it requires very little force to break it free. The wall of the motor case will not actually be engaged by the ISC rather the lower portion of the air frame will nest in the front and help provide axial stability and allow for ease of separation.

 

[AndrewW]

Looking forward to the details. My two cents: 1) HEI solves one set of problems and replaces them with another set. I've worked on projects that used HEI and not been happy with the results. A commercial tested solution would be great. 2) Whatever seems safe enough to you may not pass muster with everyone that has to sign off for a 50K+ flight at BALLS, and I'm not sure what will be judged acceptable for HEI going forward.

I completely agree with this and that is why we have put so much time into the safety and procedural aspects of our design. Again here we did not try to reinvent the wheel rather we referred to hundreds of pages of industry and NASA documents and tried to learn from what they have tested and use in their ignition systems, many of which are man rated.

If the TRA committee deems our system unsafe or unacceptable I will defer to their judgement and seek an alternative. Again with safety in mind if someone with considerable experience questions how or why you are doing something you had better stop and listen.

 

[OverTheTop]

A couple of comments:

Firstly if you would like to look at a HEI design I used you can find the info here. You may have already seen this if you flicked through the build I mentioned earlier in your thread: https://forum.ausrocketry.com/viewtopic.php?f=8&t=6385

Secondly, be very wary of tapers locking when mated. Think about how a Morse taper works in a drillpress. Quite well. The angle of the taper needs to be sufficiently wide to ensure the two don't lock together. IIRC the angle is something like the arctan of the reciprical of the coeffecient of friction, to provide a non-locking taper. You might need to confirm that. My flight had a cone at the top and an anulus down lower that was just a parallel fit. I kept the materials the same so the coeffecent of thermal expansion would not cause any of the fine clearances to bind, otherwise the clearances would have needed to be wider thus resulting in a less rigid coupling.

 

[JimJarvis50]

I completely agree with this and that is why we have put so much time into the safety and procedural aspects of our design. Again here we did not try to reinvent the wheel rather we referred to hundreds of pages of industry and NASA documents and tried to learn from what they have tested and use in their ignition systems, many of which are man rated.

If the TRA committee deems our system unsafe or unacceptable I will defer to their judgement and seek an alternative. Again with safety in mind if someone with considerable experience questions how or why you are doing something you had better stop and listen.

You will probably not receive many questions from Tripoli on the specifics of your design. Their function is not to review the details of your project, so don't expect them to bless what you are doing or to stop you from doing something that is not safe. You're better off floating your design here and with flyers that have had experience with what you are trying to do.

Jim

 

[AndrewW]

A couple of comments:

Firstly if you would like to look at a HEI design I used you can find the info here. You may have already seen this if you flicked through the build I mentioned earlier in your thread: https://forum.ausrocketry.com/viewtopic.php?f=8&t=6385

Secondly, be very wary of tapers locking when mated. Think about how a Morse taper works in a drillpress. Quite well. The angle of the taper needs to be sufficiently wide to ensure the two don't lock together. IIRC the angle is something like the arctan of the reciprical of the coeffecient of friction, to provide a non-locking taper. You might need to confirm that. My flight had a cone at the top and an anulus down lower that was just a parallel fit. I kept the materials the same so the coeffecent of thermal expansion would not cause any of the fine clearances to bind, otherwise the clearances would have needed to be wider thus resulting in a less rigid coupling.

Thanks again OTT. I have spent quite a bit of time reviewing your HEI design. I especially liked your use of the SMA connector.

Thanks for the information on tapers. I definitely had not thought about the possibility of it locking similar to a MT. After getting a bit worried and doing some quick research it does look like we should be ok as we are using a much wider taper angle (~18 degree half angle) which is significantly larger than 7 degrees which I have seen mentioned as the largest angle to be used for reliable locking. We could also lessen the likely hood of locking by lowering the coefficient of friction between the two surfaces. Either way I think I will devise a few tests to see if causes any issues.

 

[AndrewW]

You will probably not receive many questions from Tripoli on the specifics of your design. Their function is not to review the details of your project, so don't expect them to bless what you are doing or to stop you from doing something that is not safe. You're better off floating your design here and with flyers that have had experience with what you are trying to do.

Jim

Hey Jim, Thanks again. I will indeed post details about the HEI system we are using. We still have some testing we are trying to get done but it has been difficult in light of the current situation. I will try to get some pictures of what we have so far up soon. I would very much appreciate your feedback as well as others who have experience with this sort of thing.

 

[Steve Shannon]

I completely agree with this and that is why we have put so much time into the safety and procedural aspects of our design. Again here we did not try to reinvent the wheel rather we referred to hundreds of pages of industry and NASA documents and tried to learn from what they have tested and use in their ignition systems, many of which are man rated.

If the TRA committee deems our system unsafe or unacceptable I will defer to their judgement and seek an alternative. Again with safety in mind if someone with considerable experience questions how or why you are doing something you had better stop and listen.

One thing to consider is the ability to safe the head end igniter by physically isolating it from any current source.

You will probably not receive many questions from Tripoli on the specifics of your design. Their function is not to review the details of your project, so don't expect them to bless what you are doing or to stop you from doing something that is not safe. You're better off floating your design here and with flyers that have had experience with what you are trying to do.

Jim

I agree that the OP will get more input here.
It’s important to know that there are three different reviews.
First is the C3RC review. This is strictly a service that’s provided to help the flyer obtain a Class 3 COA and to try to avoid excursions of any existing COA. This has absolutely nothing to do with flight safety.
Second is a review that will be jointly done by the BoD and BALLS staff (or other very capable review staff such as KLOUDBusters have) before you even come to BALLS (or whatever Tripoli venue you hope to attend). This review is safety oriented.
Third and final is the on-site RSO staff review. This examines the as-built project also for safety and has absolute control over whether it flies.

 

[mikec]

One thing to consider is the ability to safe the head end igniter by physically isolating it from any current source.

I can't install a conventional igniter in a motor until I'm at the pad or in a designated prep area. I presume the same applies to an HEI system, correct?

 

[Steve Shannon]

I can't install a conventional igniter in a motor until I'm at the pad or in a designated prep area. I presume the same applies to an HEI system, correct?

Correct.

 

[JimJarvis50]

Second is a review that will be jointly done by the BoD and BALLS staff (or other very capable review staff such as KLOUDBusters have) before you even come to BALLS (or whatever Tripoli venue you hope to attend). This review is safety oriented.

Steve, I don't recall having been subjected to the second review. Is this a new procedure? What about student projects by the way? Is there anything unique about their approval?

Jim

 

[Steve Shannon]

Steve, I don't recall having been subjected to the second review. Is this a new procedure? What about student projects by the way? Is there anything unique about their approval?

Jim

It’s mostly seamless, especially for people who have flown a few of these flights, and we started it after the incidents in 2018.
Student flights require the involvement and approval of experienced mentors.

 

[JimJarvis50]

It’s mostly seamless, especially for people who have flown a few of these flights, and we started it after the incidents in 2018.
Student flights require the involvement and approval of experienced mentors.

Glad to hear it's being done. It has bothered me that I have never been asked a question about a flight. If I can help on reviews, let me know.

I had a student team asking about procedures and I mentioned the mentor requirement, but didn't know if there was anything else that they would need to do.

Jim

 

[Steve Shannon]

Glad to hear it's being done. It has bothered me that I have never been asked a question about a flight. If I can help on reviews, let me know.

I had a student team asking about procedures and I mentioned the mentor requirement, but didn't know if there was anything else that they would need to do.

Jim

Thanks, Jim. You’d be a great reviewer. I’ll pass that along to the board.

 

[AndrewW]

Second is a review that will be jointly done by the BoD and BALLS staff (or other very capable review staff such as KLOUDBusters have) before you even come to BALLS (or whatever Tripoli venue you hope to attend). This review is safety oriented.

Thank you so much for your input on this Steve. Is there a way to work with the BoD and/or BALLS staff prior to a complete project submission to perhaps discuss some of the particulars. As so many of the design choices on a project like this are inter-related I would hate to discover at the last minute that there is a particular issue that may concern them requiring a change. At that point it may be impossible to implement so I would rather have a discussion about it sooner than later. I feel like we have a good handle things regarding safety but it would be helpful to get their input as well.

Thanks.

 

[mikec]

Is there a way to work with the BoD and/or BALLS staff prior to a complete project submission to perhaps discuss some of the particulars.

Reasonable question. Last year for BALLS I submitted my Class 3 package on 5/17 and got no feedback until 9/1, then some questions from the BALLS organizers on 9/2 and 9/5 (for a launch on 9/20). Fortunately the questions were easy to address and didn't result in any substantial changes to my design, but it definitely added to the stress level to be iterating that close to the launch. More time for the process would be an improvement, as there's really not time to change anything substantial in that little time.

I'd also be happy to review stuff, not that I have anything like a successful track record at BALLS.

 

[Steve Shannon]

Thank you so much for your input on this Steve. Is there a way to work with the BoD and/or BALLS staff prior to a complete project submission to perhaps discuss some of the particulars. As so many of the design choices on a project like this are inter-related I would hate to discover at the last minute that there is a particular issue that may concern them requiring a change. At that point it may be impossible to implement so I would rather have a discussion about it sooner than later. I feel like we have a good handle things regarding safety but it would be helpful to get their input as well.

Thanks.

I don’t know. Frankly the process was not very efficient. 2019 was the one and only time we’ve done this. We worked from the submissions to the C3RC, which really are not very useful in evaluating ground operations or even recovery systems. I didn’t even actually see the submissions that the C3RC saw; I received the evaluations that the C3RC produced. It was a frustrating experience.

Reasonable question. Last year for BALLS I submitted my Class 3 package on 5/17 and got no feedback until 9/1, then some questions from the BALLS organizers on 9/2 and 9/5 (for a launch on 9/20). Fortunately the questions were easy to address and didn't result in any substantial changes to my design, but it definitely added to the stress level to be iterating that close to the launch. More time for the process would be an improvement, as there's really not time to change anything substantial in that little time.

I'd also be happy to review stuff, not that I have anything like a successful track record at BALLS.

The sad fact is very few people flying extreme projects have a successful track record, but I think that there’s value to peer reviews.
I’m sorry also for the tardiness of the reviews. The C3RC evaluations take a significant amount of time and of course they’re all volunteers. They really work hard to do their analyses.
We received the evaluations while we we’re attending LDRS over the Labor Day weekend. LDRS is pretty busy for most of the board members so we did not get to discuss the submissions until after LDRS. We actually had a conference call while I was waiting for a plane in Wichita. I raised my concerns based on what I saw or didn’t see and then deferred to senior BALLS staff to follow up. It turned out that I was unable to attend BALLS for family reasons; leaving my wife to be cared for by others twice in one month was more than my conscience would tolerate.
I believe we need a better review process but I don’t know what that must be. The one thing I know is that we must get better at safe recovery.

 

[JimJarvis50]

I don’t know. Frankly the process was not very efficient. 2019 was the one and only time we’ve done this. We worked from the submissions to the C3RC, which really are not very useful in evaluating ground operations or even recovery systems. I didn’t even actually see the submissions that the C3RC saw; I received the evaluations that the C3RC produced. It was a frustrating experience.


The sad fact is very few people flying extreme projects have a successful track record, but I think that there’s value to peer reviews.
I’m sorry also for the tardiness of the reviews. The C3RC evaluations take a significant amount of time and of course they’re all volunteers. They really work hard to do their analyses.
We received the evaluations while we we’re attending LDRS over the Labor Day weekend. LDRS is pretty busy for most of the board members so we did not get to discuss the submissions until after LDRS. We actually had a conference call while I was waiting for a plane in Wichita. I raised my concerns based on what I saw or didn’t see and then deferred to senior BALLS staff to follow up. It turned out that I was unable to attend BALLS for family reasons; leaving my wife to be cared for by others twice in one month was more than my conscience would tolerate.
I believe we need a better review process but I don’t know what that must be. The one thing I know is that we must get better at safe recovery.

Well, it could be worse. For two events, I received my approval after I started the trip.

Just for perspective, this year, I reviewed all of the two-stage projects for Spaceport (planned for June). There were about 10 of them, and I was mainly reviewing to ensure safety for the electronics approach and for HEI if it was being used (we're otherwise not supposed to provide much in the way of direct help - it's a competition). The first round of reviews was in early February, right after the first round of progress reports was received. I probably spent 40 hours reviewing submissions and communicating (harrassing) the teams. The second review was mid March, right after the second submission. About the same time required and goals. There would have been a third review in mid May, except that the event was cancelled. For student teams, starting this early is essential to be able to intervene in time and provide some degree of instruction. Much less time should be required for Balls flights.

My observation for Balls is that information is submitted early enough for a review (I have submitted information as early as February for Balls), but that the review is put off for whatever reason until much later in the process. Just my observation ....

Jim

 

[FredA]

The one thing I know is that we must get better at safe recovery.

AGREE, 1 million percent.
Let's get back to requiring a rocket fly it's planned flight on a L3 cert. - proper dual deployment if built as a DD rocket
Stop "sloppy certs" where main at apogee is a pass.
Proper recovery - it should be the minimum.
Proper DD recover should really be the minimum.

Sorry - don't mean to Hijack this thread - just couldn't let that pass.

 

[tfish]

Maybe some helpful info in this...
https://aeropac.org/Newsletters/Fall_2018.pdf

Tony

 

[AndrewW]

The sad fact is very few people flying extreme projects have a successful track record, but I think that there’s value to peer reviews.
I’m sorry also for the tardiness of the reviews. The C3RC evaluations take a significant amount of time and of course they’re all volunteers. They really work hard to do their analyses.

Steve, I believe you mentioned you had worked in the utility industry previously. My current job involves testing and commissioning of protection and control systems in HV and EHV substations. I completely agree with you that peer review is extremely valuable. It is a major tenant of the engineering process and when done correctly can lead to major reductions in mistakes, errors and accidents. The problem I see all too often though is lack of resources both human and time. What I am seeing more and more of lately are significant errors making it to the field. Things that should have been caught but due to only cursory reviews by engineers that already have a lot on their plate managed to make it by.

We received the evaluations while we we’re attending LDRS over the Labor Day weekend. LDRS is pretty busy for most of the board members so we did not get to discuss the submissions until after LDRS. We actually had a conference call while I was waiting for a plane in Wichita.

It sounds like you may be having some of the same resource issues. Having only two to three weeks to review these type of projects seems to be a bit tight in my opinion especially if any changes need to be made. Having personally already invested many thousands of dollars not to mention equally as many hours as well scheduling my entire year around this, it would be a bit more comforting to know that we are good to go and have a safe and thoroughly reviewed design. I must be honest this whole part of the process worries me. Perhaps a suggestion. could you possibly utilize some members of the organization like Jim or TAPs with similar experience to sponsor these type of projects. They could help be the go between to help set expectations and provide guidance along the way so that when a final review is made most of the detail have already been discussed. This would also allow the project to be viewed at a much earlier stage in the design and perhaps any red flags could be addressed long before they make it to the final product.

I for one welcome a thorough review, as stated earlier my number one goal for this mission is safety.

One of my favorite sayings from my days when I thought climbing mountains was "fun" was:

"Getting to the top is optional, getting down is mandatory!"

Well since we all know that no rocket we have flown has ever stayed up there maybe an adapted mantra could work for us:

"Getting it up there is optional, getting it down safely is mandatory!"

 

[AndrewW]

Maybe some helpful info in this...
https://aeropac.org/Newsletters/Fall_2018.pdf

Tony

Thanks Tony, I have seen that before and actually after finding it I went back and read thorough every Aeropac news letter I could find. They are a great resource and have a ton of interesting information in them. The interstage coupling design in the article on the PX4 actually first sparked the idea behind the inverted cone in our ISC. I know ours is the opposite of his but the idea of a self centering easy to release joint that is strong under compression is brilliant. I believe it was also used by several sounding rockets as well as a team by MIT.

Andrew

 

[AndrewW]

So back to the project. This is not really a true build thread, so my apologies if it seems a bit all over the place. That being said if you want to see something specific and it is something we have finished then I will try to get some pics posted. I had a really busy week at work and only got a few nights in this week to work on things.

The first thing I got done was to make slots in both body tubes. I know this topic has come up in the past as whether or not to slot body tubes for MD projects. I believe there are pros and cons of both arguments so I kind of came up with a hybrid idea. I call it a castellated or intermittent slot. I think pictures explain it best. This design helps maintain fin alignment and BT structural integrity and well as provide a little additional mechanical support. I have used this on several other MD projects and other than some additional work I think it has some real benefits.

 

[AndrewW]

I also finished up the machining on the front closure for the booster motor as well as the motor retainer and front av bay cover. This will hopefully make more sense as I start to put everything together.

Andrew

 

[Steve Shannon]

Steve, I believe you mentioned you had worked in the utility industry previously. My current job involves testing and commissioning of protection and control systems in HV and EHV substations. I completely agree with you that peer review is extremely valuable. It is a major tenant of the engineering process and when done correctly can lead to major reductions in mistakes, errors and accidents. The problem I see all too often though is lack of resources both human and time. What I am seeing more and more of lately are significant errors making it to the field. Things that should have been caught but due to only cursory reviews by engineers that already have a lot on their plate managed to make it by.



It sounds like you may be having some of the same resource issues. Having only two to three weeks to review these type of projects seems to be a bit tight in my opinion especially if any changes need to be made. Having personally already invested many thousands of dollars not to mention equally as many hours as well scheduling my entire year around this, it would be a bit more comforting to know that we are good to go and have a safe and thoroughly reviewed design. I must be honest this whole part of the process worries me. Perhaps a suggestion. could you possibly utilize some members of the organization like Jim or TAPs with similar experience to sponsor these type of projects. They could help be the go between to help set expectations and provide guidance along the way so that when a final review is made most of the detail have already been discussed. This would also allow the project to be viewed at a much earlier stage in the design and perhaps any red flags could be addressed long before they make it to the final product.

I for one welcome a thorough review, as stated earlier my number one goal for this mission is safety.

One of my favorite sayings from my days when I thought climbing mountains was "fun" was:

"Getting to the top is optional, getting down is mandatory!"

Well since we all know that no rocket we have flown has ever stayed up there maybe an adapted mantra could work for us:

"Getting it up there is optional, getting it down safely is mandatory!"

I really like this idea, to assign each project to a TAP.
Great post.

 

[AndrewW]

Got a few more things done over the past couple of days. Most of the work was completed on the Booster av bay which will utilize a 3/8" bolt directly to the booster motor front closure for retention. It will also have 6 6-32 screws to align it with the BT and then two 1/4"-20 rods will hold the whole assembly together on either side of a 2.5" section of coupler epoxied into the upper section of the air frame. The upper section of coupler will hold the recovery chutes and harness. The ISC fits in the upper portion if this coupler which nests within the top portion of the booster air frame. I hope this is all making some sense:

Andrew
KD2RPB

 

[AndrewW]

So here is a question for you guys out there with some extreme altitude flight experience. How do you set up your apogee deployment channels. I know above 90k' the baro altimeter is not very effective and what seems like the best option is to go with a timer based off of sim data but how do you cover the entire flight envelope in case of an off nominal launch. I was originally planning on using the normal apogee channel which should cover me up to about 90k' in case of a booster failure or perhaps a sustainer ignition failure but I am worried about having it left in above that altitude do to a possible deployment due to noise. I am using a Telemega and Raven to provide these functions. One thought I had is to use the other pyro channels available and have them configured to deactivate if above 90k and ascending. Any ideas on this would be great. I am going to reach out to each of the products designers but I thought it would be a good idea to tap into some of the talent available on this forum as well.

Thanks,
Andrew