New Method for Parachute Deployment? Deployment by Rocket Extraction

[caralbur]

I am a member of a newly founded rocketry team in my University. We are very excited to build our first rocket, however, we have no prior knowledge. Upon investigating different methods for Dual Deployment Systems, Theo W. Knacke in his book "Parachute Recovery System Design Manual" mentions a recovery system by means of a rocket with angled nozzles located at the nosecone.

We found this to be very interesting and I personally did not find a anyone tring to achieve this. I found that the DARE project at TU Delft considered this approach back in 2019, explaining that despite having many potential benefits, testing was too complicated. Our rocket will deploy a drogue and the main bag housing the main parachute alltogether (I believe this approach is called "In-Line" but please correct me if I am wrong). Thanks to previous posts I understood that the rule of thumb is to eject the drogue parachute to a length of about 5-6 times the body diameter in order for clean air to inflate the drogue.

I know that this method souds flashy and overly complicated for something that can be easily achieved by a simple pyrotechnic ejection. However, I understand that as rockets get bigger, pyrotechnic extraction is substituted by other approaches like aerodynamic extraction of a drogue parachute with a pilot chute, or even pistons or mortar style deployments. These either requiere the rocket to have a certainly speed to work or a heavy supporting structure to enable the deployments. If the objective is to minimize weight and for the deployment to occur as far and as close at apogee as possible, wouldn't this Rocket Extraction method be very practical?

I would love to know your opinion. Thank you!

 

[user 30299]

It's an interesting approach to parachute deployment. But I think we first should see and hear about your level of experience in designing & building high-power (HPR) rockets. Does your University team have a mentor or faculty advisor with HPR experience? Are you currently enetered in a competition, and if so which one?

 

[dhbarr]

For my money the necessary careful wire work puts it out of the realm of what I would consider practical for most teams and/or fields.

EDIT: Note I'm not saying it can't be done, I'm saying it probably shouldn't be someone's first attempt at staged clusters.

 

[DAllen]

Sorry but there aren't enough details to go on here. Size of rocket? Is this for a rocket competition - if so which one? What other details can you provide?

To be quite blunt, I really doubt putting a rocket motor large enough to pull a chute is going to save you any weight at all. Remember, not only do you have the motor itself but you're going to have to come up with an ignition system with a controller, battery, etc. which is going to be pretty hard to get lower weight than a few grams of FFFF. I've never heard of a HPR flier using a system like this for any rocket no matter how large. Maybe there's a reason for that.

For REALLY large HPR rockets in our hobby the only other successful deployment method I've heard of is using automotive airbags. Steve Eves did this IIRC on his gigantic Sat V about 10-12 years ago.

The other thing that concerns me a bit is the safety aspect. You're going to have a rocket motor go flying off the end of the rocket nose tethered to a chute. What is going to happen to that motor once it reaches the end of that tether? How are you going to prevent the chute from being destroyed by the thrust of the motor? Certainly not insurmountable design issues but something to consider.

 

[caralbur]

Sorry but there aren't enough details to go on here. Size of rocket? Is this for a rocket competition - if so which one? What other details can you provide?

Yeah sorry I wanted to keep the thread discussing the system in general and not specifically for our case.

We want to join the EuRoC 2022 Competition for a 3000 m (≈ 10.000 ft) solid propellant rocket. Our rocket will measure around 2.2 m (≈ 7'2 ft), diameter of 13 cm (≈ 5'1 inches) with a weight of around 13 kg (≈ 29 lbs). We will use pyrotechnic ejection and we have succesfully tested it on smaller rocket. We were wondering if this Rocket Extractor method would be feasible. I highly doubt we will be able to design and test this system, if we eventually decide to try it, for this year's competition.

My idea as of right now is to ignite a small charge on the very tip of the nozzle capable of pulling on the folded drogue chute and its chords. The burn time would be small enough so that there is no way for the small rocket to keep pulling on the parachute with all the length of chord that needs to be pulled. Also, Theo W. Knacke in its book states that the burn time was so small that protection agiants the hot gases was never an issue. However, we would still need to investigate it further with testings. I intend this to be my Final Degree Project with my Aerospace Engineering Degree.

 

[caralbur]

Does your University team have a mentor or faculty advisor with HPR experience? Are you currently enetered in a competition, and if so which one?

We are a team located in the Polythecnic University of Valencia, Spain. The first Team in the city and third of the country. Model rocketry is far less common here in Europe than in the US. Even though we are all mostly undergraduates of Aerospace Engineering, none of us, including advisors, have any model rocketry experience. Advisors have worked extensively in solid propulsion, aerodynamic surfaces and so on, but never actually built a HPR.

We want to join the EuRoC 2022 Competition for a 3000 m (≈ 10.000 ft) solid propellant rocket. Our rocket will measure around 2.2 m (≈ 7'2 ft), diameter of 13 cm (≈ 5'1 inches) with a weight of around 13 kg (≈ 29 lbs). We will use pyrotechnic ejection and we have succesfully tested it on smaller rocket. We were wondering if this Rocket Extractor method would be feasible. I highly doubt we will be able to design and test this system, if we eventually decide to try it, for this year's competition.

 

[tsmith1315]

http://www.tripoli-spain.org/

It would be well worth your time and effort to go to one of the Tripoli launches and see these rockets in action.

 

[boatgeek]

Is it a good idea? Honestly, seems way too complicated. And I would definitely want to see a standard pyrotechnic backup. Even without a pyrotechnic backup it wouldn't save any weight.

The only way I could imagine this working is something like the following:

The nose cone with deployment bag has an easy slip fit into the upper body tube. To prevent drag separation, it's secured with a rod that's retracted by servo close to the altitude at which you want to release the main. At the appropriate altitude, an altimeter in the nose cone fires 3-4 canted motors near the base of the cone. These would probably be something like A8s, though a high-thrust, short-burn motor like a B14 would be better if you could find them. The motors drag the nose cone off and deployment bag free. Ideally, they'd burn out before the deployment bag reached the end of the recovery harness, but with a free bag it wouldn't make that much difference.

It would be very cool if it worked, though there are many, many practical issues to resolve first.

 

[afadeev]

We are very excited to build our first rocket, however, we have no prior knowledge. [....] a recovery system by means of a rocket with angled nozzles located at the nosecone. [...]
I know that this method souds flashy and overly complicated for something that can be easily achieved by a simple pyrotechnic ejection.

Indeed.
More like needlessly complicated and totally unnecessary for the problem at hand.
With no prior rocketry experience, it would strongly advise to avoid any and all unnecessary complexity in your first model rocket competition attempt.

However, I understand that as rockets get bigger, pyrotechnic extraction is substituted by other approaches like aerodynamic extraction of a drogue parachute with a pilot chute, or even pistons or mortar style deployments. These either requiere the rocket to have a certainly speed to work or a heavy supporting structure to enable the deployments. If the objective is to minimize weight and for the deployment to occur as far and as close at apogee as possible, wouldn't this Rocket Extraction method be very practical?

No.
Stick to tried-and-true dual-deployment via black-powder ejection charges triggered by an altimeter.
Anything else, with your level of inexperience, is 100% asking for an exotic failure.

We want to join the EuRoC 2022 Competition for a 3000 m (≈ 10.000 ft) solid propellant rocket. Our rocket will measure around 2.2 m (≈ 7'2 ft), diameter of 13 cm (≈ 5'1 inches) with a weight of around 13 kg (≈ 29 lbs).

That weight estimate is grossly out of whack with the objective of reaching 10K feet.
What motor are you planning to use?

You rocket could be narrower, and should be way WAY lighter, if your only objective is reaching 10K foot attitude.
For example, you could stick a J-motor in to 1.6" Go Devil and see north of 14+K feet in altitude with the total take-off weight of ~1.8 kg.
https://www.madcowrocketry.com/1-6-fiberglass-go-devil/

My idea as of right now is to ignite a small charge on the very tip of the nozzle capable of pulling on the folded drogue chute and its chords. The burn time would be small enough so that there is no way for the small rocket to keep pulling on the parachute with all the length of chord that needs to be pulled. Also, Theo W. Knacke in its book states that the burn time was so small that protection agiants the hot gases was never an issue. However, we would still need to investigate it further with testings.
[...]We were wondering if this Rocket Extractor method would be feasible. I highly doubt we will be able to design and test this system, if we eventually decide to try it, for this year's competition.

Feasible and appropriate (for the problem at hand) are two entirely different concepts.
Building a rocket to fly to the moon is definitely feasible (BTDT), but way outside of the realm of what would be appropriate for your project, given your experience level.
I would put your proposed ejection approach into the same answer category.

a

 

[MidOH]

An escape tower? LES.
https://en.wikipedia.org/wiki/Launch_escape_system

Isn't ''head end deploy'' pretty much the same thing? Just make a separate tip, to blow off of the nose cone, instead of the entire thing.

 

[ep29030]

When you use shear pins on the nosecone, fire an ejection charge to break the shear pins and eject the nosecone, then let the inertia of the nosecone pull a deployment bag off the parachute, you are effectively doing the same thing as your proposal, with less complexity and weight. Your goal is to stretch out the lines of the parachute before inflation, to lessen opening forces. Either a deployment bag or skirt hesitator can accomplish this.

 

[user 30299]

An escape tower? LES.
https://en.wikipedia.org/wiki/Launch_escape_system

Isn't ''head end deploy'' pretty much the same thing? Just make a separate tip, to blow off of the nose cone, instead of the entire thing.

Good point there. I have an HED rocket. But aren't we back to adding complexity (motors, igniters, etc.), in the student's proposal, to just put out a chute?

 

[user 30299]

We are a team located in the Polythecnic University of Valencia, Spain. The first Team in the city and third of the country. Model rocketry is far less common here in Europe than in the US. Even though we are all mostly undergraduates of Aerospace Engineering, none of us, including advisors, have any model rocketry experience. Advisors have worked extensively in solid propulsion, aerodynamic surfaces and so on, but never actually built a HPR.

We want to join the EuRoC 2022 Competition for a 3000 m (≈ 10.000 ft) solid propellant rocket. Our rocket will measure around 2.2 m (≈ 7'2 ft), diameter of 13 cm (≈ 5'1 inches) with a weight of around 13 kg (≈ 29 lbs). We will use pyrotechnic ejection and we have succesfully tested it on smaller rocket. We were wondering if this Rocket Extractor method would be feasible. I highly doubt we will be able to design and test this system, if we eventually decide to try it, for this year's competition.

I appreciate the honesty on your team's and advisor's HPR experience. A great way to start! I get to work with teams in some of the university competitions so I see some "interesting" approaches to designs and rocket fabrication. I have had the opportunity to review projects from teams that have participated in EuRoC. These are teams that are looking to enter competitions in the US. Seriously, it's always good to keep your designs simple the first time. No matter what, the goal is to have a good launch and a good & safe recovery. Use your first trip to EuRoC as an opportunity to learn from the experienced teams. Every team likes to share information, along with their good & bad experiences. Remember to keep it fun . . . .

 

[JoePfeiffer]

This looks like a very cool idea, unfortunately coolness shouldn't be a factor in engineering decisions.

My suggestion would be to get some experience with a conventional dual deploy rocket first, then ask yourself three questions regarding this system: Will it be more reliable? Will it be lighter? Will it be cheaper? Unless you are pretty sure it'll come out ahead on one of the three criteria and doesn't have too much cost in the other two (and doesn't cost reliability at all) you should stick with conventional.