Project Blacksky 200K two stage - Class 3 submitted!

Good afternoon everyone, and welcome to the official thread for the flight of illimitato, my 2 stage sounding rocket and 200,000ft attempt. This project has been an ongoing effort of mine for a little over 4 years now, and slowly but surely it has worked its way from being sketches in a notebook to being a real, simulated design, ready for build… only not quite yet!

The design has reached a finalized stage, and almost everything has been quoted and planned out, except for a machine job of the interstage transition. Over the course of the next few months I intend to sniff out a machinist willing and able, and set up a Kickstarter profile for funding, as I expect this project to be quite expensive (See linked budgeting sheet) . During this period it will also undergo TRA Class III board of reviewal, and a waiver to 300,000 feet will be secured.

The plan is to fly at either the AeroNaut, XPRS or BALLS 2015 launches at Black Rock Desert, as both of these provide a prime launching environment.

Designed to be stable from 100mph to mach 5, the vehicle will be built from only the most premium materials available for the task in order to survive extreme aerodynamic loading. In a temporarily airtight avionics bay, it will be lofting a GoPro Hero4 Black Edition, capturing 4Kp30 footage of the entire ride up, in portrait orientation. The concept of the project is to capture a quick transition from blue to black sky as the rocket leaves the atmosphere, and to go really really high!

I have been working on this project for a long time now, continuously consulting with a team of highly experienced rocketeers formed by friendship at Black Rock Desert launches and others. I am confident in the success of the design based on the rather tried and true profiles of the stages, but I am excited to learn what I can from any results of flight overall. I am hopeful that I can inspire enough rocketry enthusiasts and science lovers around the world to help me achieve this feat, as it is not something I can financially support on my own. If you would like to donate to the cause, the Kickstarter funding page will be set up shortly. I need to find that machinist first!

All documentation for the project is now available for public review, including but not limited to the overall project writeup, a budgeting sheet of forecasted costs, exported simulative data from OR, simulative models from OR and RAS and all 3D CAD models of the vehicle. If you would like to know something, don’t hesitate to ask!

As always I appreciate everyone stopping by to have a look at the project, and I thank everyone sincerely whom can contribute to it in any way.

Kickstarter: (Not Available Yet)
Facebook: Facebook.com/ProjectBlacksky
-----
Project Writeup: https://www.dropbox.com/s/qrnum5bnlb3oghp/Project BlackskyPDF.pdf?dl=0
Budget sheet: https://www.dropbox.com/s/o2fibzeb4ael0bw/PRBS.docx?dl=0
N5800 OR Sim Data: https://www.dropbox.com/s/27l48bqp6jcq0h6/n5800wtf.csv?dl=0

Happy Flyin!
Ryan

View attachment illi85s.ork

View attachment BooRaS.alx1

View attachment SusRAS.alx1

So basically a 2 stage motor condom.

A VERY awesome project! I'll be watching and learning. I've been meaning to go to a launch at Black Rock. I might just use this as an excuse.

Excited to see this build progress to completion.

Dropbox links are not working for me.

However, I am really excited to watch this happen.

BLKKROW said:

Dropbox links are not working for me.

However, I am really excited to watch this happen.

Click to expand...

Fixed! Will update in original post! Thanks

Will definitely be keeping an eye on this project!
Best of luck to ya!

Wire EDM will probably be your friend on that interstage coupler.

Sweet! Looking forward to this!

I may be stupid but in the documentation you mentioned having an air tight AV bay and then opening it up to allow the barometer to trigger the events.

However, once you introduce pressure into that AV bay might it trigger an event at that moment?

BLKKROW said:

I may be stupid but in the documentation you mentioned having an air tight AV bay and then opening it up to allow the barometer to trigger the events.

However, once you introduce pressure into that AV bay might it trigger an event at that moment?

Click to expand...

Not stupid at all! The atmospheric pressure in the avbay will be that of 3900' MSL (ground level) untill depressurization, at which point it will drop (climb in altitude) all the way up to about 10,000ft MSL, which is about where I hope to depressurize.. there will indeed be a moment where it is at inflation altitude, yes, but it will be *climbing* and thus pyro activation will not be triggered. Furthermore, I can install a timed lockout feature starting from accelerometer based apogee detection that exceeds the time set for de-pressurization, that will ensure that baro data gets ignored untill a few moments after the avbay has been breathing.

I think this should solve that problem pretty elegantly. Any thoughts?

Frozenferrari said:

Not stupid at all! The atmospheric pressure in the avbay will be that of 3900' MSL (ground level) untill depressurization, at which point it will drop (climb in altitude) all the way up to about 10,000ft MSL, which is about where I hope to depressurize.. there will indeed be a moment where it is at inflation altitude, yes, but it will be *climbing* and thus pyro activation will not be triggered. Furthermore, I can install a timed lockout feature starting from accelerometer based apogee detection that exceeds the time set for de-pressurization, that will ensure that baro data gets ignored untill a few moments after the avbay has been breathing.

I think this should solve that problem pretty elegantly. Any thoughts?

Click to expand...

No, it's not an elegant solution, and furthermore this problem does not exist today with modern altimeters. Most current altimeters are running a Kalman filter and/or have an automatic velocity driven mach lockout to prevent mach transients from triggering which totally eliminates the need for an explicit mach lockout.

A bigger issue is that a MEMS pressure sensor based altimeter based deployment systems will not function much above 100Kft because they are not sensitive enough to observed the small pressure changes as you ascent from 100Kft to 200Kft. For that you need a GPS based altimeter system with an inertial platform backup such as Kate https://www.multitronix.com/ or Altus Mentrum https://altusmetrum.org/TeleMetrum/ Both also provide real-time tracking information so you will know where your rocket is during the flight and most importantly, where it landed.....and I'll assume that the FAA will/should require some type of real-time tracking for a flight to this altitude.

Bob

bobkrech said:

No, it's not an elegant solution, and furthermore this problem does not exist today with modern altimeters. Most current altimeters are running a Kalman filter and/or have an automatic velocity driven mach lockout to prevent mach transients from triggering which totally eliminates the need for an explicit mach lockout.

A bigger issue is that a MEMS pressure sensor based altimeter based deployment systems will not function much above 100Kft because they are not sensitive enough to observed the small pressure changes as you ascent from 100Kft to 200Kft. For that you need a GPS based altimeter system with an inertial platform backup such as Kate https://www.multitronix.com/ or Altus Mentrum https://altusmetrum.org/TeleMetrum/ Both also provide real-time tracking information so you will know where your rocket is during the flight and most importantly, where it landed.....and I'll assume that the FAA will/should require some type of real-time tracking for a flight to this altitude.

Bob

Click to expand...

I believe He is using a Telemega.

bobkrech said:

No, it's not an elegant solution, and furthermore this problem does not exist today with modern altimeters. Most current altimeters are running a Kalman filter and/or have an automatic velocity driven mach lockout to prevent mach transients from triggering which totally eliminates the need for an explicit mach lockout.

A bigger issue is that a MEMS pressure sensor based altimeter based deployment systems will not function much above 100Kft because they are not sensitive enough to observed the small pressure changes as you ascent from 100Kft to 200Kft. For that you need a GPS based altimeter system with an inertial platform backup such as Kate https://www.multitronix.com/ or Altus Mentrum https://altusmetrum.org/TeleMetrum/ Both also provide real-time tracking information so you will know where your rocket is during the flight and most importantly, where it landed.....and I'll assume that the FAA will/should require some type of real-time tracking for a flight to this altitude.

Bob

Click to expand...

I am using RFS GPS-1 for primary GPS, Telemega for backup GPS and CSI RF tracking. Apogee deployment is based primarily on accelerometer detecting V<0, and also backed up by a timer based apogee deployment. What we are discussing is LOW altitude pyro event logic, not apogee logic. Please read the writeup again if needed, this is explained there.

Ryan has clearly shown an ability to build and launch very high speed Mach 2.9+ rockets that apogee at ~30 Kft. There is a difference however when you attempt to go to over 100kft where fins don't necessarily provide sufficient aerodynamic control to keep a rocket on vertical flight path which is why aerodynamically controlled sounding rockets are spin stabilized. Additionally there are significant difficulties in exceeding Mach 3 from a materials standpoint as the aerodynamic heating increase as M^3. Careful trajectory control is required to prevent everything from overheating in the lower atmosphere, or from being crushed by extremely high dynamic pressure. Boosting from ground to a velocity ranging from Mach 1.5-2 than coasting through the dense lower atmosphere to 25-30 kft before igniting the second stage greatly reduces the aerodynamic heating and drag losses associated with high Mach travel through the dense lower atmosphere.

Bob

This is a great project, Ryan! I'm really looking forward to the building of this rocket and the flight.

We do have the possibility to add another 1400 Ns to the N5800 design. Burn time would increase to ~5 sec. More like an O4,300. Would that help for this project? Or do you prefer the higher lift-off thrust?

Jeroen

bobkrech said:

Ryan has clearly shown an ability to build and launch very high speed Mach 2.9+ rockets that apogee at ~30 Kft. There is a difference however when you attempt to go to over 100kft where fins don't necessarily provide sufficient aerodynamic control to keep a rocket on vertical flight path which is why aerodynamically controlled sounding rockets are spin stabilized. Additionally there are significant difficulties in exceeding Mach 3 from a materials standpoint as the aerodynamic heating increase as M^3. Careful trajectory control is required to prevent everything from overheating in the lower atmosphere, or from being crushed by extremely high dynamic pressure. Boosting from ground to a velocity ranging from Mach 1.5-2 than coasting through the dense lower atmosphere to 25-30 kft before igniting the second stage greatly reduces the aerodynamic heating and drag losses associated with high Mach travel through the dense lower atmosphere.

Bob

Click to expand...

I have never seen a rocket suddenly go off trajectory after passing through 100,000 feet. Newton's laws dont warrant that. I can provide countless videos proving that fin guided rockets have no issues going over 100,000 such as Neil Anderson's 'A Money Pit' which hit 118,000 feet.
[video=youtube;VnNNnqB5AJM]https://www.youtube.com/watch?v=VnNNnqB5AJM[/video]

Aeroheating is a significant concern indeed, and thus I have decided to apply a 5000F thermal ablative to the exterior of the nosecone and upper airframe. I also have indeed seen cases where slight alpha can increase stress on a nosecone and promote micro fracturing (leading to nosecone explosion) This is why the rocket was designed to be atleast 1.0 cal stable at the highest expected velocity. The hope is that if it does cone, it wont cone enough to cause damage.
Again, this is all discussed in the writeup.

Jeroen_at_CTI said:

This is a great project, Ryan! I'm really looking forward to the building of this rocket and the flight.

We do have the possibility to add another 1400 Ns to the N5800 design. Burn time would increase to ~5 sec. More like an O4,300. Would that help for this project? Or do you prefer the higher lift-off thrust?

Jeroen

Click to expand...

WOW!!! Well, That depends! I would need to see a data sheet detailing propellant and loaded weight, and somehow add the thrust curve to OpenRocket and RAS to simulate, but off the back of my hand I would assume that profile would bridge the gap between the O3400 boost and the N5800 boost profiles. My guess is that it would burn out around 6500AGL @ mach 2.05 ish. This would probably still result in around the same overall altitude. To be honest with you, given the O3400 exists, I think it's kindof moot. I had considered the O3400 so I could keep boost aerodynamic loading low, and conserve impulse for lower drag environments. Yet, the N5800 still stood out as best due to it's supreme rail departure velocity. But I am interested in giving it some looking into!

I will be in contact with you shortly about custom machining the Pro75 hardware, as we had discussed some time ago in the private messages.
Dude, you rock!

Frozenferrari said:

WOW!!! Well, That depends! ...... To be honest with you, given the O3400 exists, I think it's kindof moot.

Click to expand...

Not quite. The mass fraction of the N5800 is much better because the C* propellant has a much higher Isp then the O3400. You can use the N5800 data, and add 0.634 kg of propellant. Burn-out weight would be the same as the N5800 motor. The O4300 would have more total impulse then the O3400 and weigh about 3 pounds less at lift-off.

It would just not be an "N" anymore.

Jeroen

Jeroen_at_CTI said:

Not quite. The mass fraction of the N5800 is much better because the C* propellant has a much higher Isp then the O3400. You can use the N5800 data, and add 0.634 kg of propellant. Burn-out weight would be the same as the N5800 motor. The O4300 would have more total impulse then the O3400 and weigh about 3 pounds less at lift-off.

It would just not be an "N" anymore.

Jeroen

Click to expand...

Okay, this is sounding like it is definitely worth some simulative overview. I will fire up EngEdit and take a look at what I may modify with the N5800 file, but are the thrust curves significantly different, other than length? Specifically, peak thrust? Would you guys happen to have a thrust curve I could just grab in an email and plug n' go?
I am still placing the utmost priority on rail guide departure, so I will look critically at this with the O4300 and compare that performance with booster burnout, sustainer ignition and sustainer apogee performance. I will tell you right now that if nothing REALLY jumps out at me in the latter 3, I will not compromise the first for only a slight gain In other words, I will stay with the N5800 for its winning departure speed unless this proves to be a significantly better motor for the other reasons.

I'm really excited to hear about this. I probably won't make it to Black Rock this year, but if I do I'll definitely try to be there for this launch.

Frozenferrari said:

I have never seen a rocket suddenly go off trajectory after passing through 100,000 feet. Newton's laws dont warrant that. I can provide countless videos proving that fin guided rockets have no issues going over 100,000 such as Neil Anderson's 'A Money Pit' which hit 118,000 feet.

Click to expand...

I never said it suddenly went off trajectory after passing 100 kft. If you look at the video you posted however, you will see the horizon "waving" in the video. That is due to coning, AKA roll-pitch coupling, that is not damped out as the rocket ascends into thinner and thinner air. IMO it's likely the flight in the video lost 10Kft. or more in apogee due to the coning of the rocket.

Aeroheating is a significant concern indeed, and thus I have decided to apply a 5000F thermal ablative to the exterior of the nosecone and upper airframe. I also have indeed seen cases where slight alpha can increase stress on a nosecone and promote micro fracturing (leading to nosecone explosion) This is why the rocket was designed to be at least 1.0 cal stable at the highest expected velocity. The hope is that if it does cone, it wont cone enough to cause damage.
Again, this is all discussed in the write-up.

Click to expand...

Coning is a dynamic instability that no hobby sims are programed to predict because you don't have the actual 3D GC and aerodynamic information required to predict it if the equations were in the sims.

Coning causes a buckling failure of the airframe because the airframe goes sideway in a high Mach flow and the dynamic pressure load bends and then breaks the airframe. Ancillary heating is not relevant or important as the vehicle is destroyed before the heating occurs.

A few comments from a professional in the area of high temperature materials.

1. Plain old phenolic resin carbon fiber composite is a 5000+ F ablator.

2. Unless you're using a ceramic nose cone, you'll never see a micro-fracture failure in a nosecone.

3. Composite nosecone don't undergo explosive failures unless they're filled with HE........they will simply soften, buckle, and/or delaminate.....

Bob

It is hard to tell if that is true coning, but I will take your word for it. I would think onboard video of coning wouldnt 'wobble' like that, but rather stay tilted to one side and just rotate. But even having said that, I fail to see how Neil's rocket's behavior changes much after burnout, though. From the high 30 thousands all the way to where it starts to arc over, it seems to behave relatively uniformly. That is all that will really matter. 6DOF simulators like OpenRocket seem to do a pretty good job forecasting alpha in flight, it seems. We've seen designs that are marginally stable experience more drag and result in lower altitudes. Is this simulated coning? Truthfully, I dont know. I would think so, but I am no simulator professional. It may not be pitch-yaw-roll coupling, but there is definitely something to be said for alpha simulation in OR and its resulting drag consequences.
1. My nosecone must not be carbon fiber as this would block telemetry. There was some discussion about adding a phenolic glaze to the exterior of the G12 one, but I would need a reliable person or shop to custom wind the parts. To be honest, there's enough quotes Ive had to track down already. Id rather just stick with an off the shelf part since it will work.
2. Micro fractures are indeed invisible to the naked eye. Hence the name. But you get a composite piece to start humming with harmonic vibration and those microfractures spread into *VERY* visible fractures. To put it bluntly, the nosecone turns into confetti.
3. "Explosion" was just the word I used (albeit incorrectly) . It turns the nosecone into confetti. Lets say it that way. Seen it happen.

When a component hums and fails, it's a flutter or flexural failure. When its a fin or a wing, that's a fin or wing flutter failure. Flutter failure is due to insufficient stiffness in the material, so when this happens you have a design failure. The cure is to either make the material thicker to increase the stiffness, or to increase the modulus to make it stiffer. The professional solution would be to use a CF composite NC (or a metal NC if using a metal airframe) and use 2 conformal patch antennas on opposite sides of the airframe for 4pi steradian RF coverage......

Bob

So I looked a bit at your budget.

Your interstage budget number is my first question. Does that include machine time? I am assuming you would need a 4.5" round bar stock to make the interstage since your max diameter is 4 in if I am not mistaken.

7075 T651 round bar stock in 4.5" diameter runs about $180 a foot. You could buy 7 feet of it for ~$1000. That inter stage if that is what picture 4 is has some extremely complicated geometry, and looks very difficult to machine in one piece. Main problem are the 4 (holders?) in the front, the inside surface being beveled like that will require a cnc lathe and a lot of boring time, then you will have to do perhaps two other machining processes to finish them. If i were you I might go back and reference things like the Super Loki or Viper sounding rockets (you are pretty much making one), and look at their interstate setup. Those are much more machinable and cheaper to make.

Also for your metal stock try locally first. I priced out 200' of 316L stainless tubing and it was ~$25,000 from on online shop (McMaster), locally I could get the exact same thing for $3500, and this is local in Alaska which would be a bit more expensive.

Only downside is for small amounts they might not have some of the specialty metals in stock, however you might be able to do a sponsorship with them a bit easier than a large corporation. Meaning they might at least be willing to order the minimum amount for them of something you need, but only sell you what you need from it.


The metal for your fins will be more expensive than what you expect, I think you would probably need more than just 1 sq foot of Grade 5 to make your fins, though I didn't actually look to see how big yours are.

So two sq feet of 1/8 grade 5 Ti sheet is about $850 from an online store https://www.mcmaster.com/#9039k26/=xa84qe.

For your fincan, it looks relatively similar to the fincan I made for my rocket, just a bit more complicated. I don't think they make 7075 in 5" dia x 1" wall as a stock form, so you might have to buy round stock and bore it out yourself. It took me about 40 hours of machine time to make my fincan, with about another 20 hours making the work-holding fixtures. Granted I do not work nearly as fast as a professional machinist, but with the additional boring, as well as the more complicated geometry of your tabs 30 hours for a professional machinist doesn't seem all that unreasonable. Standard shop time is $125+ depending on the shop. So $2000 - $3000 isn't an unreasonable estimation for how much it will cost to make.

Your fins look very complicated to manufacture especially out of Titanium. The main way I could see manufacturing them would be a surface grinder, since they are really thin. it might be tough to machine them. I don't really have much of a feeling for how long they would take, but for 4 of them it is probably a long time.

You have a lot of complicated machined pieces in this project, some of them a bit unnecessarily complicated from a manufacturing standpoint. If you were to pay full price for all of them $12,000 in machine time alone doesn't seem unreasonably far from the mark.

If I were you I would redesign some of your pieces with better manufacturability in mind, even if it might cost you a little bit in altitude. Since the lower you can make your rocket cost, the more likely it is to get off the ground to begin with.

Once you get to the point you are ready to machine things, I would try some mom and pop machine shops that are local to you. Go in person, tell them about your project. Offer to help anyway you can (even if you don't have machining experience) because you want to learn how to machine things (because you should considering how much machined parts you have). Start with some of the easier to make parts, and in working with them you will learn what goes into machining things, and might end up wanting to revise your design from the things you learn.

Why would the FAA care if the waiver is for 200k or 300k? It's not like any airplanes are going to be there. I'm just curious.

I look forward to following your progress.

Swissyhawk said:

Why would the FAA care if the waiver is for 200k or 300k? It's not like any airplanes are going to be there. I'm just curious.

I look forward to following your progress.

Click to expand...

Higher the altitude, the larger your landing range needs to be.

Frozenferrari said:

Apogee deployment is based primarily on accelerometer detecting the rocket is sideways,.

Click to expand...

Can't be done. Except for aerodynamic forces the rocket will be in free fall. And at that altitude the aerodynamic forces will be nearly non-existent.

I checked your document describing this project because I thought that surely anyone considering such a project would not have such a poor understanding of basic physics. Alas, I was wrong: "Therefore the systems will watch first for accelerometers to read nearly horizontal trajectory"

Titanium can be had pretty cheaply from titaniumjoe.com I used a fair bit off it from there. Also surface grinding large thin titanium plates would be difficult since it won't hold to a magnetic chuck. I spend a lot of my time at work simplifying parts for low volume manufacturability and I agree that you'll want to simplify your parts to remove multiple machining setups, speed roughing, and avoid complex cnc programming. In small quantity runs these things will make an order of magnitude or more impact on costs.

UhClem said:

Can't be done. Except for aerodynamic forces the rocket will be in free fall. And at that altitude the aerodynamic forces will be nearly non-existent.

I checked your document describing this project because I thought that surely anyone considering such a project would not have such a poor understanding of basic physics. Alas, I was wrong: "Therefore the systems will watch first for accelerometers to read nearly horizontal trajectory"

Click to expand...

Correct me if I'm wrong but it depends on the board's orientation. If it's measuring acceleration only in the Y direction, the acceleration before arcing over in relation to the board will be negative. However, once it arcs over the rocket will continue to have the same negative acceleration but because the board's orientation is reversed, the board will read it as positive. During that arc as the board's perceived acceleration changes from negative to positive. At some point it should hit 0 acceleration in the Y direction. Deployment can be triggered at that point. Of course this won't work if there is backsliding because the board's orientation will always be the same.

Alex

Xrain-
First off, I sincerely appreciate the in depth post! To start off, those numbers you see on my budget are pure guesses. They would be all inclusive, meaning the exact cost to go from drawings on my laptop to part in hand. I have semi-adequate models in .DWG format. Chris has graciously offered assistance in making more machinist-oriented models in more adaptable formats, as well as attempting to help me locate a shop willing and able to work with me. This being said, my current designs may indeed need a re-vamp to be more machine friendly.

My thinking is that for the Interstage, the majority of the work can be done first on a CNC lathe, and then 5 axis mill or wire EDM to cut the slots between the tongues and add the chamfers to them. However, I am not sure at all that this would be as easy as it sounds, or even possible. It is again just a guess on my part. The only machine experience Ive had before was with 3 axis milling.

I am stiff on changing the design of the interstage away from single piece machined, but I am not completely closed to the idea of a re-design. My thinking is that the tongues could maybe be engineered to slide into slots and then be locked in with a pin, or set screws, or possibly even bonded. But my worry with this design is weakened overall strength and integrity. What do you think?

I really do not want to change the weight or length around too drastically as everything must be redone for every single little change. All simulations must be re-run, and all models updated, to once again prove that the design will remain stable under all operating regimes. But more importantly, it seems that total length comes at a high price with this rocket.

Yes, the fincan is quite similar indeed to what you have done in the linked thread. I will for sure read that whole thread very closely and thoroughly tonight. Where did you get the 5" dia number from? The fin can sleeve can be machined from a 4" diameter rod or tube with .5" wall. Originally, I had the fillets to be 1/2" wide and 1/2" tall, but as Chris was explaining to me, a slight height reduction allowed for the stock to be an even 4" .

Indeed, another thing we had discussed was the ease of machining of the fins. As I am learning, a precision machine job putting on a true diamond airfoil and bringing them down to super thin tips would indeed be exceedingly hard with titanium, so I am looking at alternative shaping. I think I may just mill a standard hexagonal airfoil and allow the LE and TE thickness to be what it must to keep machining costs reasonable.

I should start again from square one with the interstage. A clean slate. Again, I REALLY want to keep the length the same, and the sleekness. But I am just not seeing how. Maybe it will come to me. I think making the IST two parts (tongues and transition) will dramatically help, but I dont see it fixing the issue entirely. Im open to any and all suggestions for changing it.

Again, I really appreciate everyone's time and thoughts they are putting into this with me. The rocket was founded on teamwork and will continue to evolve and live all the way to launch day on teamwork. Any input is good input. If you have ideas pitch them to me, I need em!