Recovery system for 30k ft bi-liquid rocket

RAPdanstar · Oct 23, 2018

Hey rocketeers!

I'm Rasmus and currently writing on behalf of DanSTAR, the rocket club at the Technical University of Denmark. We are currently developing a bi-liquid rocket (IPA and N2O, feed system is pressure regulated N2) for the IREC at Spaceport America Cup 2019.

However, seeing as rocketry is not a big thing here in Denmark, we are having a really hard time figuring out how to do an efficient and light-weight recovery system. It needs to be two stage, and we plan on ejecting our nose cone. Our approximate dryweight for the rocket will be 55 kg.

I assume you guys here are very knowledgeable on this, and seeing as all of DanSTAR is completely green here could you maybe direct us at a way to look?

Best regards,
Rasmus

Eric · Oct 23, 2018

There are several great recovery companies. Fruity chutes make very high quality recovery devices. As well as top-flight recovery. But I would check out BAMA recovery systems. They are doing a lot of new and different style parachutes recently.

https://www.bamachutes.com

RAPdanstar · Oct 23, 2018

Eric said:
There are several great recovery companies. Fruity chutes make very high quality recovery devices. As well as top-flight recovery. But I would check out BAMA recovery systems. They are doing a lot of new and different style parachutes recently.

https://www.bamachutes.com

This is exactly the kind of reply I had hoped for! Thank you so much Eric

What about BAMA do you like in particular?

tim cubbedge · Oct 23, 2018

Here are a few more to consider:
https://www.b2rocketry.com/
https://www.the-rocketman.com/chutes.html

Eric · Oct 23, 2018

timbucktoo said:
Here are a few more to consider:
https://www.b2rocketry.com/
https://www.the-rocketman.com/chutes.html

Those are great companies as well. I only have one rocketman chute, but Buddy is great to work with.

As for BAMA, they are new to hobby rocketry. But I believe the owner has more history in the industry. Last weekend I flew in a parachute contest. BAMA recovery took first and second place. They are coming out with some more radical designed chutes, then whats currently on the market. I just used a bundle of three chutes. Packed super small and had a great descent rate.

But he was going to do 3 ring sail chutes, and ive never seen that in a hobby rocket.

They are also putting out a few chutes that rotate. There performance and stability was great.

This was Thisrty's chute that took 1st place. It was spinning at about 30 rpm on the way down.

JimJarvis50 · Oct 23, 2018

One thing to keep in mind is that at IREC, you will be required to aim your rocket at nominally a 5 degree angle at launch. Thus, you will probably have a significant horizontal velocity at apogee. With "out the top" deployment, the rocket will need to make a 180 degree turn when the chute catches air. This will put stress on your harness and on the air frame. Many teams will use this approach, but on the other hand, there is a reason (reliability) why the tried-and-true dual deployment approach is so prevalent, where the rocket first breaks in the middle of the air frame.

Jim

If you must use an out the top approach, my recommendation would be to use something like a tender descender to retain the main chute, in a deployment bag, inside the air frame, and then have your pilot/drogue pull it out at the main deployment altitude.

RAPdanstar · Oct 23, 2018

JimJarvis50 said:
One thing to keep in mind is that at IREC, you will be required to aim your rocket at nominally a 5 degree angle at launch. Thus, you will probably have a significant horizontal velocity at apogee. With "out the top" deployment, the rocket will need to make a 180 degree turn when the chute catches air. This will put stress on your harness and on the air frame. Many teams will use this approach, but on the other hand, there is a reason (reliability) why the tried-and-true dual deployment approach is so prevalent, where the rocket first breaks in the middle of the air frame.

Jim

If you must use an out the top approach, my recommendation would be to use something like a tender descender to retain the main chute, in a deployment bag, inside the air frame, and then have your pilot/drogue pull it out at the main deployment altitude.

Considering how extensive the electronics system needs to be for a homebuilt bi-liquid rocket, I have a feeling that seperating the rocket on the middle (aka just above the fluid system) will potentially cause us a lot of problems with exposed electronics. I might be wrong though.

Would you care to elaborate a bit on your out-of-the-top approach? Unfortunately, I only understood half of the words

JimJarvis50 · Oct 23, 2018

RAPdanstar said:
Considering how extensive the electronics system needs to be for a homebuilt bi-liquid rocket, I have a feeling that seperating the rocket on the middle (aka just above the fluid system) will potentially cause us a lot of problems with exposed electronics. I might be wrong though.

Would you care to elaborate a bit on your out-of-the-top approach? Unfortunately, I only understood half of the words

I'm sure that the bi-liquid rocket will cause problems separating in the middle. However, I recommend you at least consider the alternatives.

I don't really have a good drawing of the out the top approach, but pages 14-16 of this document probably come the closest.

https://docs.wixstatic.com/ugd/b73de9_5001759fdb0af2876b1af634c7dfe908.pdf

An alternative to the Tender Descender L3, which may not be available to you, is a similar device called an AARD. The concept is that you have a strong attachment point in your deployment bay. The release mechanism is attached to that point. There are two harnesses that are attached to the release mechanism. One line goes to your drogue. At apogee, the drogue comes out and is connected to the air frame at the release mechanism. The other harness goes to the top of the deployment bag. The deployment bag is connected to the top of the main chute, and the shroud lines are connected to a third harness, which is connected to another hard point in your bay. Simple! When the release mechanism activates, the pilot pulls on the second harness and pulls the deployment bag out of the air frame, extends the shroud lines out of the bag, and then opens the chute. You'll need to research this a little, but it will be worth your time.

Do not be tempted to use a Chute Release or some other tethering method where the chute falls from apogee and is outside of the air frame. Your rocket is too large for that approach in my opinion.

Jim

RAPdanstar · Oct 23, 2018

JimJarvis50 said:
I'm sure that the bi-liquid rocket will cause problems separating in the middle. However, I recommend you at least consider the alternatives.

I don't really have a good drawing of the out the top approach, but pages 14-16 of this document probably come the closest.

https://docs.wixstatic.com/ugd/b73de9_5001759fdb0af2876b1af634c7dfe908.pdf

An alternative to the Tender Descender L3, which may not be available to you, is a similar device called an AARD. The concept is that you have a strong attachment point in your deployment bay. The release mechanism is attached to that point. There are two harnesses that are attached to the release mechanism. One line goes to your drogue. At apogee, the drogue comes out and is connected to the air frame at the release mechanism. The other harness goes to the top of the deployment bag. The deployment bag is connected to the top of the main chute, and the shroud lines are connected to a third harness, which is connected to another hard point in your bay. Simple! When the release mechanism activates, the pilot pulls on the second harness and pulls the deployment bag out of the air frame, extends the shroud lines out of the bag, and then opens the chute. You'll need to research this a little, but it will be worth your time.

Do not be tempted to use a Chute Release or some other tethering method where the chute falls from apogee and is outside of the air frame. Your rocket is too large for that approach in my opinion.

Jim

We are looking into the mid-section deployment.

It looks to me like The Tender Descender is a pyrotechnic device? Danish legislation is very hard on pyrotechnics (but no on bi-liquid rockets, go figure) so we would prefer gas or spring based recovery.
I'm afraid I still don't understand your explanation. I'm sure it makes plenty of sense to someone who is seasoned, but could you maybe try with a simple sketch? Thank you for being so patient haha

JimJarvis50 · Oct 23, 2018

RAPdanstar said:
We are looking into the mid-section deployment.

It looks to me like The Tender Descender is a pyrotechnic device? Danish legislation is very hard on pyrotechnics (but no on bi-liquid rockets, go figure) so we would prefer gas or spring based recovery.
I'm afraid I still don't understand your explanation. I'm sure it makes plenty of sense to someone who is seasoned, but could you maybe try with a simple sketch? Thank you for being so patient haha

If i have a chance, I'll try to come up with a sketch. In the meantime, what are you planning for your dual deploy?

Jim

AlphaHybrids · Oct 23, 2018

Something to seriously consider is the impulse limit for IREC. The motors are limited to 9,208 pound-seconds or 40,960 Newton-seconds. I have been involved with the two teams that have successfully flown a liquid at IREC and both of them were in the 3000 pound-second range with their motors, while only attaining less than 5,000 feet in altitude. Even scaling their systems, I have significant doubts that they could hit 30,000 feet with three times as much propellant. I'm sure it can be done on paper, but the difficulty is getting everything to transfer to the real world.

N2O is self pressurizing and having an additional nitrogen pressurant adds mass with debatable benefit to the motor.

I see your motor is 3.1kN, which if you use the entire impulse range that is a 13 second burn time. At a 5:1 thrust:weight ratio your rocket can weigh 140 pounds (3.1kN is ~700 lbs). If you get an ISP of 190s your propellant maximum mass is ~48 pounds. The mass adds up very quickly, and rocket diameter can as well.

Edward

RAPdanstar · Oct 23, 2018

JimJarvis50 said:
If i have a chance, I'll try to come up with a sketch. In the meantime, what are you planning for your dual deploy?

Jim

We are planning on a drogue chute to deploy at apoge to reduce descent velocity to a 75-150 ft/s range. At approx. 500 m AGL the main chute will deploy and reduce the velocity furhter to less than 30 ft/s. This is purely based on competition rules though.

RAPdanstar · Oct 23, 2018

AlphaHybrids said:
Something to seriously consider is the impulse limit for IREC. The motors are limited to 9,208 pound-seconds or 40,960 Newton-seconds. I have been involved with the two teams that have successfully flown a liquid at IREC and both of them were in the 3000 pound-second range with their motors, while only attaining less than 5,000 feet in altitude. Even scaling their systems, I have significant doubts that they could hit 30,000 feet with three times as much propellant. I'm sure it can be done on paper, but the difficulty is getting everything to transfer to the real world.

N2O is self pressurizing and having an additional nitrogen pressurant adds mass with debatable benefit to the motor.

I see your motor is 3.1kN, which if you use the entire impulse range that is a 13 second burn time. At a 5:1 thrust:weight ratio your rocket can weigh 140 pounds (3.1kN is ~700 lbs). If you get an ISP of 190s your propellant maximum mass is ~48 pounds. The mass adds up very quickly, and rocket diameter can as well.

Edward

This is derailing the topic quite a bit, so I won't respond further to similar questions in this thread, but feel free to send me a message or tell me if we should discuss this in a new thread - I'd love to

I am aware of the impulse limit. We have experience with operating a N2 pressure fed system using N2O and IPA from our previous demonstration engine and test facility. Video here.
We are weight optimising to the extreme and using anisogrid carbon fiber sections for the hull along with a bare minimum of aluminium bracing. We are constructing a common bulkhead tank out of duplex steel, so I can ensure you every measure is being taken to reduce weight. Our team has done an extremely good job of raising sponsorships and funds and as such, we have amazing opportunities (such as 3D printing the engine to be regeneratively cooled too). Lots of credits through bachelor thesises and special courses are being put into the project to ensure we actually have the proper background for taking on a challenge like this. Currently the weight of the rocket is hovering around 50kg to 55kg with options to weight reduce further.

As for the self pressurising N2O, yes you're absolutely right. However, as we are already planning on transitioning to LOX we felt we might just as well use a pressure regulated system as LOX will be needing this.

JimJarvis50 · Oct 23, 2018

RAPdanstar said:
We are looking into the mid-section deployment.

It looks to me like The Tender Descender is a pyrotechnic device? Danish legislation is very hard on pyrotechnics (but no on bi-liquid rockets, go figure) so we would prefer gas or spring based recovery.
I'm afraid I still don't understand your explanation. I'm sure it makes plenty of sense to someone who is seasoned, but could you maybe try with a simple sketch? Thank you for being so patient haha

So, here is your sketch. Remember, it is free!

There are three parts to the sketch. The first part is everything assembled at the top of the rocket. Hopefully, the parts are clear.

The second part of the drawing is after the nose cone comes off at apogee. The cone could be pushed off by gas I suppose. The rocket falls under the green drogue which is connected to the red release mechanism. The release mechanism could be a Tender Descender, an AARD, or perhaps some sort of a servo-controlled release. The black baffle bisecs the recovery section and is intended to prevent the drogue harness from tangling with the deployment bag and main chute.

The third part of the drawing is after the release releases. The pilot pulls out the deployment bag, and then pulls the main out of the deployment bag. It opens in a controlled manner, which is what you want. Note that it takes a second or two for this to happen. During that time, the air frame is in free fall and it accelerates. You need to account for the extra jolt when the main finally opens.

There are many details, such as how to size the drogue to fly above everything, how to keep the deployment bag and main in the air frame when the drogue deploys, how to keep the main in the deployment bag as it gets pulled out, etc. But, this is the essence of it.

Jim

RAPdanstar · Oct 24, 2018

JimJarvis50 said:
So, here is your sketch. Remember, it is free!

There are three parts to the sketch. The first part is everything assembled at the top of the rocket. Hopefully, the parts are clear.

The second part of the drawing is after the nose cone comes off at apogee. The cone could be pushed off by gas I suppose. The rocket falls under the green drogue which is connected to the red release mechanism. The release mechanism could be a Tender Descender, an AARD, or perhaps some sort of a servo-controlled release. The black baffle bisecs the recovery section and is intended to prevent the drogue harness from tangling with the deployment bag and main chute.

The third part of the drawing is after the release releases. The pilot pulls out the deployment bag, and then pulls the main out of the deployment bag. It opens in a controlled manner, which is what you want. Note that it takes a second or two for this to happen. During that time, the air frame is in free fall and it accelerates. You need to account for the extra jolt when the main finally opens.

There are many details, such as how to size the drogue to fly above everything, how to keep the deployment bag and main in the air frame when the drogue deploys, how to keep the main in the deployment bag as it gets pulled out, etc. But, this is the essence of it.

Jim

Hi Jim,

You're an absolute baller! Thank you so much

In the mean time I've gotten a quote from Fruity Chutes with something that seems very reasonable. Currently looking at they HAWK CO2 deployment system along with some other stuff. I've attached the current quote to this post.

JimJarvis50 · Oct 24, 2018

RAPdanstar said:
Hi Jim,

You're an absolute baller! Thank you so much In the mean time I've gotten a quote from Fruity Chutes with something that seems very reasonable. Currently looking at they HAWK CO2 deployment system along with some other stuff. I've attached the current quote to this post.

My personal preference on deployment bags is to go with a tube design rather than a flap. My belief is that this approach can keep the chute in the bag until it's pulled open. You don't want to pull on the bag and have the chute stay behind. Just my preference.

I would suggest being very careful selecting the drogue size. Need to consider the descent rate of the rocket under main versus the descent rate of the drogue based on the cone weight (so they don't interfere with each other). I might go with a Rocketman drogue versus a fruity chute.

Jim

AlphaHybrids · Oct 24, 2018

Jim - do you ever use the free bag setup?

Edward

JimJarvis50 · Oct 24, 2018

AlphaHybrids said:
Jim - do you ever use the free bag setup?

Edward

I think you're asking about a case where the bag would pull off the chute and then recovery separately? For the drawing I provided, this would be achieved by removing the connection from the bag to the top of the main chute.

In my description of the setup, I mentioned properly sizing the drogue and main chutes so that they don't interfere with each other. The problem is you don't want the drogue to fall into the main chute or to pull up to hard on the top of the main chute. A fine alternative is to free bag the main chute and then let the drogue/cone/bag recover separately. That gets rid of the interference and I think would be more reliable, but the downside is obviously having to find two separate pieces.

I usually have tracking equipment in the nose cone, so I try not to free bag, but it would be the highest reliability approach. I think in this case, though, that it shouldn't be that hard to size the chutes.

Jim

markkoelsch · Oct 25, 2018

Would you be able to post a drawing or sim with general location of tanks etc? Might help to give you a better starting point.

BAMA_Recovery_Systems · Oct 25, 2018

Eric said:
Those are great companies as well. I only have one rocketman chute, but Buddy is great to work with.

As for BAMA, they are new to hobby rocketry. But I believe the owner has more history in the industry. Last weekend I flew in a parachute contest. BAMA recovery took first and second place. They are coming out with some more radical designed chutes, then whats currently on the market. I just used a bundle of three chutes. Packed super small and had a great descent rate.

Thank you Eric for the mention. I may be new to the hobby chutes market but I have a long list of accomplishments with parachutes. Just a few quick highlights; FAA certified parachute rigger, constructed chutes as large as 75 ft in diameter, highest successful deployment with a main parachute was 109,000 ft MSL (28ft skirt reefed), worked on multiple recovery systems for aerospace/ space companies, pressure packed parachutes to very high densities (mechanical and vacuum methods), mentored by some of the top parachute experts in the world, jumped out of planes, rigged loads up to 30,000 lbs to be dropped out of planes, developed wing-suit specific pilot chute, one of only ~4 people to construct an article in space (cannot specify what this is) and currently work in the parachute industry professionally.

Rocket parachutes present a different challenge to other recovery systems. Hobby/ sport rockets are even more demanding in the restrictions on pyro, weight, and cost. These unique challenges are why BAMA Recovery Systems was formed, to not only bring professional aerospace/ space technology and materials to the hobby but also to educate, inspire and gain feedback/data on unique and sometimes revolutionary recovery systems.

As far as my input for this post, I would love to weigh in but I am working with another team in the same competition.

Eric · Oct 25, 2018

I was just assuming.... And I was right... BJ knows his chutes.

AlphaHybrids · Oct 25, 2018

BAMA_Recovery_Systems said:
As far as my input for this post, I would love to weigh in but I am working with another team in the same competition.

I mentor multiple teams for the competition. I tell all the teams this, but I do no share information across the teams. Being involved with one team does not exclude you from working with others, unless that is your personal preference.

Edward

JimJarvis50 · Oct 25, 2018

BAMA_Recovery_Systems said:
As far as my input for this post, I would love to weigh in but I am working with another team in the same competition.

I will likely be consulting with a number of the teams going to this competition (or maybe I'll just be kibitzing with them until they stop listening). Given that bringing the rocket down safely is really important, I would hate to think that folks with expertice are not sharing it because it's a "competition". It's a learning experience - one that we would like to be as safe at as possible.

Jim

BAMA_Recovery_Systems · Oct 25, 2018

AlphaHybrids said:
I mentor multiple teams for the competition. I tell all the teams this, but I do no share information across the teams. Being involved with one team does not exclude you from working with others, unless that is your personal preference.

Edward

I agree that it doesn't exude me from working with other teams. I just feel that I have offered my best recovery plan to another team and not offering a plan equally as great or better would limit the new team. Now if they had an idea that they need references or manufacturing for I would never turn them away. I just feel that if I developed an idea without their input it would compromise the original team. One example of a work around. Yes, pyro is hard to get over in Denmark, but not impossible. Using a spring launched pilot chute or main using a Cypress Automatic Activation Cutter would be possible. These are very reliable, used in skydiver's reserves, and can be acquired in Denmark.

BAMA_Recovery_Systems · Oct 25, 2018

JimJarvis50 said:
I will likely be consulting with a number of the teams going to this competition (or maybe I'll just be kibitzing with them until they stop listening). Given that bringing the rocket down safely is really important, I would hate to think that folks with expertice are not sharing it because it's a "competition". It's a learning experience - one that we would like to be as safe at as possible.

Jim

Jim, Safe recovery is the most important thing. That being said, there is a huge difference between solving engineering obstacles that would give an edge to a team and providing a generic system that will safely recover the system. There are 1000's of different parachute designs and one may be a better solutions but all may provide a safe recovery.
Here is a for instance, say a team wanted to separate the booster at supersonic speeds and wanted to forgo electronics or staging in the booster to save weight and have better performance in the main stage. There is not a hobby parachute vendor that I know who can provide this system. Does this limit the team from competing or having a safe recovery? No, it simply means they will not be able to optimize weight and have the same performance. Now if I designed this system and another team came to me asking for my thoughts on ways to increase performance of the main stage, listed similar issues to the team that I've been working with, should I provide the same set up or offer a set up that is not as good?

AlphaHybrids · Oct 25, 2018

When you see how these rockets are constructed an edge in recovery is quickly eliminated by multiple 3/4" thick Home Depot plywood centering rings scatter shot throughout the rocket. Or 24 1/4-20 machine screws holding in an airframe bulkhead on a 6" rocket.

I will share my best ideas with all the teams. Jim hit the nail on the head - most will take the information you give them and then do their own thing, they are after all engineers and know what is best.

Edward

JimJarvis50 · Oct 25, 2018

BAMA_Recovery_Systems said:
Jim, Safe recovery is the most important thing. That being said, there is a huge difference between solving engineering obstacles that would give an edge to a team and providing a generic system that will safely recover the system. There are 1000's of different parachute designs and one may be a better solutions but all may provide a safe recovery.
Here is a for instance, say a team wanted to separate the booster at supersonic speeds and wanted to forgo electronics or staging in the booster to save weight and have better performance in the main stage. There is not a hobby parachute vendor that I know who can provide this system. Does this limit the team from competing or having a safe recovery? No, it simply means they will not be able to optimize weight and have the same performance. Now if I designed this system and another team came to me asking for my thoughts on ways to increase performance of the main stage, listed similar issues to the team that I've been working with, should I provide the same set up or offer a set up that is not as good?

I'm not talking about providing the same system or a specific design. I was responding to your statement that you couldn't weigh in on this thread (at all).

Jim

BAMA_Recovery_Systems · Oct 25, 2018

JimJarvis50 said:
I'm not talking about providing the same system or a specific design. I was responding to your statement that you couldn't weigh in on this thread (at all).

Jim

Sorry if I was a little too finite. Most of the safe recovery topic has already been addressed before I saw the email about this thread. The things that I would weigh in on would be the post about recovery system limitations, which I feel are not true limitations. Some of these limiting factors I have already presented as ideas or developed for other teams.

Recovery system for 30k ft bi-liquid rocket

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