Feasibility of High-Altitude 2 Stage Flight (N5800-M2245)

[Choco_mint]

Originally, I had designed this rocket just to mess around in OpenRocket, but as I'm starting to gain more experience in HPR, its becoming more and more enticing.

I plan to gain experience with High-Power staging through flying a stack of two of my already existing rockets, before I even start putting money into this build. What is the largest hurdle I'd run into? Aerodynamic Heating? Fin Flutter? Engine Ignition at High Altitude? Is there anything else I'm missing?


Here's a very barebones design, notably missing almost any mass components. My plan, currently, is to use a single deployment event in the booster and a Single-Sep DD setup in the sustainer. Getting the motors isn't too much of a concern for me, as my school has these two specific motors in its possession already, as well as all casing hardware.


I plan to put this design into RASAero to get better simulation data, due to the supersonic velocities.

Realistically, even if I do end up building this, I only have one shot at sending this thing up, so I want to be able to get as much feedback as possible before I get in too deep.

 

[waltr]

I suggest looking up Kip's 394k foot 2-stage flight.
Search this forum for threads.

 

[Choco_mint]

Thanks, let me take a look!

 

[rfjustin]

Thanks, let me take a look!

Questions about aerodynamic heating, fin flutter, and second stage ignition at high altitude are great questions, but without experience (and hopefully coaching), how are you going to address the knowledge gap here? What practical minimum diameter experience do you have to date? If the answer is none or very little, get a single stage airframe to 30,000'+ successfully first...

 

[mikec]

The booster will probably go at least 30Kfeet so I'm not sure how you think you can get away with single deploy.

It's harder than it looks. I've been flying for 15 years and I haven't succeeded in getting a two-stage M to L to work yet, and your proposed flight is a good bit more challenging.

 

[StreuB1]

And here we are, yet again.

 

[mikec]

To be charitable, there are plenty of people (usually students) who come in, play with OR for 5 minutes, and then think they can fly a rocket to 100Kfeet+ easily. Start by convincing us this isn't that.

And the "I only have one shot" is a bit of a red flag.

 

[tfish]

To be charitable, there are plenty of people (usually students) who come in, play with OR for 5 minutes, and then think they can fly a rocket to 100Kfeet+ easily. Start by convincing us this isn't that.

And the "I only have one shot" is a bit of a red flag.

he's 18 years old...

Tony

 

[rocketace]

Besides the ones you have listed, here are a few more considerations that need to be mostly sorted out in the design / test rocket phase.
- Electronics, what will do what and how will they be programmed.
- Same but with the back up electronics.
- Arming safety
- Getting a straight flight
- Getting the right design and fit of the interstage coupler
- High altitude deployments above 30k
- Not doing some type of dual deployment sounds like a very bad idea to me for this project.
- Motor retention / electronics placement / recovery mounting

If you have only 1 shot with those motors, you will need a several test fligts with smaller motors. My suggestion is work your way up.
- Fly single stage high speed flight with a 3" motor
- Fly a dual deploy to 30k....then another to 60k
After that you will better understand the complexity of this bigger project and you will know better ways of doing things. And it's fun! keep us updated on your ideas.

 

[r1dermon]

I'd be interested in the sim file. Mass with no motors is 1087grams or a hair under 2.4lbs. That's pretty ambitious.

 

[Brainstormz123]

This is basically exactly the rocket that TU Wein has tried to bring to balls basically every year, and yet to have success with. Theirs does sim a tiny bit higher, and I think it is possible to pass the karman line with those two motors in a well optimized rocket.

 

[Choco_mint]

Questions about aerodynamic heating, fin flutter, and second stage ignition at high altitude are great questions, but without experience (and hopefully coaching), how are you going to address the knowledge gap here? What practical minimum diameter experience do you have to date? If the answer is none or very little, get a single stage airframe to 30,000'+ successfully first...

I'm going to be working with rocket teams from nearby universities, which is my way to help bridge the knowledge gap through working with a handful of experienced mentors and alongside other students. I got my L2 on a 54mm Min Dia and I will be flying that rocket on an L1030 to around 20,000 feet in March. That rocket is actually a subscale of the second stage on this design, so I hope to use it as a proof of concept.

To be charitable, there are plenty of people (usually students) who come in, play with OR for 5 minutes, and then think they can fly a rocket to 100Kfeet+ easily. Start by convincing us this isn't that.

And the "I only have one shot" is a bit of a red flag.

By only one shot, I mean that I only have one set of motors to fly on a full scale flight, not that I plan to only fly that stack. As recommended by another user on the thread, I do plan on flying a lot of subscale versions of this rocket before flying the "big one."

I'm well aware this project comes with an extreme amount of complexity, which is why I asked more about the feasibility of a project like this before I really start fleshing things out. I definitely need more experience, that much is for sure!

 

[Neutronium95]

In theory, the combination of a N5800 and a M2245 can break the Karman line. In practice, nobody has had a successful flight with a sufficiently optimized rocket.

I think that your proposed development cycle of a few two stage flights before going full send is liable to not give you enough experience to pull off this flight successfully. If you want to have a good chance of success, I'd suggest both getting experience with high power staging, as well as a good background with high performance flights above Mach 3.

This talk by @Kip_Daugirdas gives a good look at what it takes to pull off an extreme performance multistage flight like this:


Here is a very non comprehensive list of things that can go wrong:

• Dynamic stability issues raising their head at Mach 3+ and your rocket taking a hard turn.
• Getting a not straight boost and having your electronics not light the second stage.
• Getting a not straight boost and having your electronics light the second stage, which flies out the side of the waiver cylinder.
• Getting past the second stage burn only for all of the electronics to stop working.
• The rocket folding in half at the interstage.
• The fins fluttering off.
• Recovery not working.

Good luck with your project. Just be aware that it won't be as easy as you think it will be.

 

[JimJarvis50]

So, against my better judgement.....

First, what is wrong with 100K? Everyone has to go to space. 100K is difficult and only a handful of people have done it. Try that perhaps?

Second, the rocket required to these high altitude flights (to 100K anyway) doesn't need to be all that special. I've tried 100K 10 times and gotten there 5 times. Generally, I'm using a very conventional dual-deploy rockets and not rockets that are optimized or purpose-built for high altitude. Many of the issues that have made this difficult in the past, such as faulty altimeters, have been solved, so it is easier to do this now than, say, 10 years ago, and there is a lot of information on successful attempts available.

Before my 10 attempts above 100K, I tried perhaps a half dozen attempts in the 50-100K range. A few were successful, but several were not. But that experience fed into the 100K attempts. So, when I see someone saying they have a one-and-done chance for a high altitude flight, well, that just seems kind of silly.

Third, you have to have a place to launch the rocket. It you want to launch at Balls, then you have to get past the Class 3 review. The first question is, how my times have you flown a minimum-diameter, two-stage rocket above, say, 50K. If the anwer is zero, then you're not going to be flying at a Tripoli launch. You would need your own COA, which might not be easy to get, and you might have to pay money for a site. This is probably the single most difficult hurdle.

Jim

 

[Brainstormz123]

Third, you have to have a place to launch the rocket. It you want to launch at Balls, then you have to get past the Class 3 review. The first question is, how my times have you flown a minimum-diameter, two-stage rocket above, say, 50K. If the anwer is zero, then you're not going to be flying at a Tripoli launch. You would need your own COA, which might not be easy to get, and you might have to pay money for a site. This is probably the single most difficult hurdle.

Jim

This problem is super easy to solve, you just go to FAR (Friends of Amateur Rocketry). For a fee of $10, they have a standing P waiver up to 250k ft, not even an RSO check or any other prerequisites.

Not saying that is a good thing to not have any questions asked, but it is the easiest way to solve the no launchsite problem.

 

[jsdemar]

This problem is super easy to solve, you just go to FAR (Friends of Amateur Rocketry). For a fee of $10, they have a standing P waiver up to 250k ft, not even an RSO check or any other prerequisites.

Not saying that is a good thing to not have any questions asked, but it is the easiest way to solve the no launchsite problem.

FAR has a standing waiver to 120K ft AGL, not 250k. This flight will require its own FAA application and COA. The clear radius at FAR is about 1/2 that of Black Rock; anything over 120kft, especially a 2-stager, will need to have a thorough risk analysis, and a track record for FAA approval.

 

[Brainstormz123]

FAR has a standing waiver to 120K ft AGL, not 250k. This flight will require its own FAA application and COA. The clear radius at FAR is about 1/2 that of Black Rock; anything over 120kft, especially a 2-stager, will need to have a thorough risk analysis, and a track record for FAA approval.

The new waiver as of 2ish months ago is a 10 mile radius cylinder and 250k ft.

However recovery 10 miles away from FAR sucks way way more than black rock.

 

[Brainstormz123]

Oh time flies way faster than I thought, its been a thing since August.

Proof:

 

[jsdemar]

I am going by what is on the FAR website. Also, the FAA would not give a clear radius which includes populated areas. 6 or 7 NM is max for that site. Also there is no such thing as a standing waiver for Class 3 rockets; above an O total combined impulse requires its own waiver.

 

[Brainstormz123]

I am going by what is on the FAR website. Also, the FAA would not give a clear radius which includes populated areas. 6 or 7 NM is max for that site. Also there is no such thing as a standing waiver for Class 3 rockets; above an O total combined impulse requires its own waiver.

I am not sure how FAR has their waiver, but it does have a standing P waiver (as is written on the FAR website), and I have seen P flights to 100k out there before without their own FAA filing. Argonia also has the standing P waiver and I have no idea how this works, but it does.

In addition, you can see from a few weeks ago Kip’s filling to the FAA for mesos with an 11 mile radius, which does include populated areas (WSA-2334-RKT is what I have written down, but dont quote me on that, it was November 4th)

I think FAR has a special situation going on with Edwards where they share the airspace, which enables them to have some interesting arrangements.

 

[Choco_mint]

So, against my better judgement.....

First, what is wrong with 100K? Everyone has to go to space. 100K is difficult and only a handful of people have done it. Try that perhaps?

Second, the rocket required to these high altitude flights (to 100K anyway) doesn't need to be all that special. I've tried 100K 10 times and gotten there 5 times. Generally, I'm using a very conventional dual-deploy rockets and not rockets that are optimized or purpose-built for high altitude. Many of the issues that have made this difficult in the past, such as faulty altimeters, have been solved, so it is easier to do this now than, say, 10 years ago, and there is a lot of information on successful attempts available.

Before my 10 attempts above 100K, I tried perhaps a half dozen attempts in the 50-100K range. A few were successful, but several were not. But that experience fed into the 100K attempts. So, when I see someone saying they have a one-and-done chance for a high altitude flight, well, that just seems kind of silly.

Third, you have to have a place to launch the rocket. It you want to launch at Balls, then you have to get past the Class 3 review. The first question is, how my times have you flown a minimum-diameter, two-stage rocket above, say, 50K. If the anwer is zero, then you're not going to be flying at a Tripoli launch. You would need your own COA, which might not be easy to get, and you might have to pay money for a site. This is probably the single most difficult hurdle.

Jim

There's nothing wrong with a lower altitude target at all, this design is based off of the biggest motors my school currently has possession of. Other than those motors, we also currently have another M2245, and a bunch of Pro54 L motors, specifically a lot of L1030s.

Looking through all of the advice that everyone has for me, here's the plan I've come up with so far, and let me know if there's anything I should add:

High Altitude flight to around 20K, good test of my ability to build a rocket that can fly high-straight-fast, and my understanding of high-altitude recovery. This rocket will be the min dia I flew for my L2, with an L1030. After that, I will fly a bunch of L1 motor-based staging attempts, keeping altitudes low to really figure out how to get staging right. My current ideas for that include some 3" to 3" staging on some mid H impulse motors. I'll probably do a 54mm to 38mm Min Dia build to cap that off, basically building a scale model of the rocket I posted initially. Then, I'll fly some High-Altitude 54mm to 54mm/ 75mm to 54mm min diameters, which will also save me a lot of money because I can use motors I already have access to. I'll use the other M2245 in my L3 build.

By that point, I think I should have enough experience to try and take a stab at tackling this particular challenge.

For now, that entire plan is me just putting ideas out there, so I can have a more sensible idea of what it takes for me to get to a point where I can launch a stack as insane as a N5800-M2245 min dia. At the time I put together that initial simulation, I was unaware that passing the karman line is possible with that motor combination. I definitely am not jumping into that build anytime soon.

I think that a realistic timeline for building all that experience is 3-5 years, so I'd say I won't be launching this thing for around 7-8 years, just to put a number in my own head. I'm in no rush to build this rocket, but I want to get there at some point.

 

[jsdemar]

I am not sure how FAR has their waiver, but it does have a standing P waiver (as is written on the FAR website), and I have seen P flights to 100k out there before without their own FAA filing. Argonia also has the standing P waiver and I have no idea how this works, but it does.

I've been informed by a knowledgeable and experienced rocket guru that the impulse limit may be waived and included in an FAA COA. That makes sense because the application allows one to list the regulations requested to be waived, and the impulse limited can be one of those items.

However, the risk analysis which determines the required clear radius is part of the FAA process and is not written into the regulations. My guess is that the airspace is already restricted by the Edwards and China Lake, so the airpsace analysis isn't needed. But the ground impact risk would have to include populated areas, and there are humans just beyond the 6NM radius.

The other factor (for those who have assets to risk) is the liability of launching without insurance. The FAA COA on hand by FAR or your own COA is not a blanket release of liability.

 

[Rschub]

In my experience, the people who are successful at projects like this don't waste effort or even think of asking other people if it's possible. They will sometimes accept advice and expertise, but the goal is their own.

 

[mikec]

The standard student pattern is to come in, ask for advice, then instantly get huffy when experienced people tell them their plans are unrealistic. Let's not recreate that (not that I think the OP's last message was trending that way, just saying.) rschub's comment above is dead on.

 

[Choco_mint]

My main intention in posting this, in all honesty, was to get a dose of reality and get my head out of the clouds, which this thread has done a great job of.

I have a good idea on how to proceed and I can't thank everyone enough for the input, I now know what my starting point for this goal is, and I know how I'm going to get to that point. However much time it takes, I don't mind as long as I'm constantly learning, safely.

One of my greatest fears as a hobbyist is doing something that could get myself, or even worse, someone else hurt, so safety is first and foremost in my mind.

I'm going to keep this thread updated as I get my start in HPR staging and hopefully use it as a fast-and-loose form of documentation for anyone else who starts out with this scale of project the same way I did.

First step? getting my 54mm Single-Stage Min Diameter to 20k feet, and back, in one piece.

From there? Well, I'm not going to get too far ahead of myself, but I have some rough plans. I'm going to start off with a 66mm (54mm motor)-66mm (38mm motor) dual stage, and try to keep it below 7K.

That's all I have for now!

 

[Neutronium95]

High Altitude flight to around 20K, good test of my ability to build a rocket that can fly high-straight-fast, and my understanding of high-altitude recovery. This rocket will be the min dia I flew for my L2, with an L1030. After that, I will fly a bunch of L1 motor-based staging attempts, keeping altitudes low to really figure out how to get staging right. My current ideas for that include some 3" to 3" staging on some mid H impulse motors. I'll probably do a 54mm to 38mm Min Dia build to cap that off, basically building a scale model of the rocket I posted initially. Then, I'll fly some High-Altitude 54mm to 54mm/ 75mm to 54mm min diameters, which will also save me a lot of money because I can use motors I already have access to. I'll use the other M2245 in my L3 build.

It's good that you're planning on building up experience before going for the full send rocket. I do have some comments and suggestions.

I'd really like to see some flights to Mach 3 and above, and also some minimum diameter staged flights.

You should also probably hang onto the second M2245. They're very hard to get these days, and having a spare motor that would let you make a second attempt at the staged flight could be valuable.

 

[MClark]

The big motors should be sold to fund projects within skill level.

 

[Rschub]

as my school has these two specific motors in its possession already,

I am a little fuzzy on how he is "obtaining" these motors anyway....

 

[3stoogesrocketry]

I am a little fuzzy on how he is "obtaining" these motors anyway....

I am a little fuzzy on how he is "obtaining" these motors anyway....

So did you read where his university has some of X motors? Moneys not issue. Common sense and experience is absolutely missing . 100 percent joking and laughing

 

[Dave P]

Rocketry development is empirical. You have to do the work. Sims are great but the mesh is not 100% accurate yet.

We see many first-time flyer are also first-time builders. Glue drips and and random globs. Coning issues. bad fits, misaligned. No power switch on electronics, etc....

We recommend getting experience with smaller rockets first. It's cheaper.

There's a reason government money was used along the way.