“Risky Business” - Minimum Diameter mach 2 attempt

[James Owen]

Can you share what specific sensors are you using?

The accelerometer that you linked to before, Adafruit’s “the ultimate GPS v3”, and I’m still undecided on the barometer. I have some BME280s, so I might stick one on there. It won’t get data all the way up but it should be able to measure what apogee is.

For radio, I’m using a pair of 900MHz LoRa transceivers from Adafruit, RFM9x I believe, which gets ~2km line of sight with default library settings and a wire antenna. With a better antenna and settings tweaked, it can supposedly go up to 20km. that’s with a directional antenna, so I’d have to track the rocket with the antenna. To know wether or not I’m pointing the antenna the right way, I might have it send little radio pulses just so I can hear beeping when antenna is pointed the right way. I’ll see if I can get ~5km (slightly less than that is acceptable) range with a more standard antenna and library tweaks, but I may have to go with the directional setup.

 

[James Owen]

FINALLY got around to making the RASAero simulation:

to compare, openrocket says 11,183 ft apogee, max vel 2,431.7 ft/sec, and 19.7s time to apogee.

Overall pretty similar, but RASAero says slightly higher up and slightly slower. Pretty minimal differences though.

With simulation done, the “in theory” stuff should be mostly over. It’ll be just a little bit before I post significant build progress but that will come. Then there will be ground deployment testing, an all-systems validation test flight on a small H motor, and then finally the i600 flight to M2.1-2.2 and 11-12k ish feet.

 

[James Owen]

Mock-up of the recovery system


I don’t have the body tube or nose cone yet so to practice packing it I shoved it in the mmt of my darkstar jr.

Repacked just to make sure I had it down (shoved it in further this time)

It’s definitely a cozy fit but the chute can still slide around in there a little so it shouldn’t have any problems with ejection.

I’ve also attached a video of the JLCR release test which I did just to make sure the way I was packing it didn’t mess with the release mechanism.

Also, thank you so much for those who’ve given advice so far and I’d really appreciate any more I can get! I’d like to say I know what I’m doing but I am still fairly new to HPR, so help is welcome.

 

[ksaves2]

Back in the day for that I did use RAS Aero paid version. Worked well. I have forgotten everything I learned with it now Hi Hi

Sheeeee00tttt Art! Been there, done that. I've forgotten alot too. Kurt

 

[ksaves2]

Shoot. I'm in awe of folks who can scratch build everything including electronics and telemetry. I never had the training to go there.
Can do motors but that's about it besides building rockets. Kurt

 

[diyaerospace]

How do you plan to do the chute release mechanism?

 

[James Owen]

How do you plan to do the chute release mechanism?

For the deployment of the chute I have a few ideas, some that are BP-less since I’m under 18, and if I can’t get those to work well enough I might have to see if I can get a mentor or something to work with me for ejection.

A jolly logic chute release holds the chute closed until the “release altitude” on descent, which is still TBD. Probably 800-1000 ft.

 

[James Owen]

Shoot. I'm in awe of folks who can scratch build everything including electronics and telemetry. I never had the training to go there.
Can do motors but that's about it besides building rockets. Kurt

Scratch building all the electronics is, in my opinion, really fun, and it ends up being cheaper than buying commercially available modules. there are pros and cons; scratch built electronics are obviously less well-tested, and they tend to be a little bulkier or heavier, but they’re cheaper and completely customizable. I try to write most of the code myself but my dad is a more experienced software guy and he usually ends up helping with that side of things.

 

[Williamhimka]

 

[David Schwantz]

Try folding your shroud lines inside the gores of the chute instead of wrapping them around it.

 

[Velocity Aerospace]

Scratch building all the electronics is, in my opinion, really fun, and it ends up being cheaper than buying commercially available modules. there are pros and cons; scratch built electronics are obviously less well-tested, and they tend to be a little bulkier or heavier, but they’re cheaper and completely customizable. I try to write most of the code myself but my dad is a more experienced software guy and he usually ends up helping with that side of things.

I'm hoping to someday get to the point where I'm able to do my own electronics. I started learning python, but I'm curious to see what language you use and what you used to learn it

 

[James Owen]

I'm hoping to someday get to the point where I'm able to do my own electronics. I started learning python, but I'm curious to see what language you use and what you used to learn it

Most of the code is done in microPython (Python adapted to work on microcontrollers), with more demanding things like on board video logging done in C. This rocket won’t have on board video though.
As far as how I learned it, lots of internet resources helped a lot. I was first introduced to python when I was like 10 or so when my dad (a software engineer) gave me a book called “Python for kids” that helped teach me the ins and outs of code.

 

[Handeman]

It's amazing the number of different types of code available and how it's changed over the years. I got my Computer Science degree in 2017 so got to use a lot of MS Visual languages, lots of C++ and Java. Over my career, I've used Octal machine code, 6800 assembler, PML to write programs to EPROMs for IBM embedded computer boards, Graphic Machine Language (GML) to program Allen Bradley servo controllers, and Microsoft Visual Basic for Applications to write Access database programs that output reports in PowerPoint and Word.
But my very first exposure to coding was a teacher that gave us a book and let a few of us work with Basic in 1970 on a 300 baud dial up teletype. The one with the yellow paper for output, a large button keyboard for input and rotatory dial on the side to connect to the main frame. It was amazing tech at that time.

Very much like what Paul Allen and Bill Gates were using in 1970 in this pic. Sure wish I had seen the potential back then like they did.

 

[James Owen]

I finalized the design with a few more minor changes, and built the rocket in OnShape.

Now to finally get around to building the thing.
Updates coming soon

 

[Velocity Aerospace]

Looks very good. I found onshape off a Google search for good cad programs and never looked back. I love using it

 

[Glasspack]

James,

I think it better to fold the shroud lines neatly in the chute instead of wrapping them. Also.....
BE SURE you ensure the band on the chute release is tight and you do a good shake test.......

My last flight with a chute release for LVL2, was not near as high or fast as your plan... but it sucks to have the JLCR slip off the folded chute at apogee.....

Best of luck -
Looks like a great fun project !!!

 

[rfjustin]

I finalized the design with a few more minor changes, and built the rocket in OnShape.
View attachment 590716View attachment 590717
Now to finally get around to building the thing.
Updates coming soon

Fin shape is nominally that of (similar to) a Mach 2 kit from Wildman. Have you considered getting the kit? It might save you some $ in the long run.
https://wildmanrocketry.com/products/mach-2-rocket

 

[BABAR]

Mock-up of the recovery system
View attachment 588402

I don’t have the body tube or nose cone yet so to practice packing it I shoved it in the mmt of my darkstar jr.
View attachment 588400
Repacked just to make sure I had it down (shoved it in further this time)
View attachment 588401
It’s definitely a cozy fit but the chute can still slide around in there a little so it shouldn’t have any problems with ejection.

I’ve also attached a video of the JLCR release test which I did just to make sure the way I was packing it didn’t mess with the release mechanism.

Also, thank you so much for those who’ve given advice so far and I’d really appreciate any more I can get! I’d like to say I know what I’m doing but I am still fairly new to HPR, so help is welcome.

Proud L-0 here, so more of a curious question.

If a rocket is anticipating a very high G launch, and the chute is a”cozy fit” on the ground at 1 G, any chance the extreme G forces can “ram” a “cozy fit” into a “potentially too tight” fit at apogee?

Best of luck, I am impressed by your extensive planning.

 

[Seatechnerd83]

Proud L-0 here, so more of a curious question.

If a rocket is anticipating a very high G launch, and the chute is a”cozy fit” on the ground at 1 G, any chance the extreme G forces can “ram” a “cozy fit” into a “potentially too tight” fit at apogee?

Best of luck, I am impressed by your extensive planning.

imo, if you fold it in the right way, and maybe lube up the tube a bit, ejection shouldnt be a problem.

 

[James Owen]

Fin shape is nominally that of (similar to) a Mach 2 kit from Wildman. Have you considered getting the kit? It might save you some $ in the long run.
https://wildmanrocketry.com/products/mach-2-rocket

sorry for taking several months to respond, but i guess its time i revive this thread.
i thought about getting a kit to do this but then decided that sounded less fun than if i did everything myself. sure i'll probably waste more money this way but if i eventually get everything to work of my own design then it'll be a better sense of accomplishment, and i figured i'd learn a lot more this way.

as far as updates to the project, launch that was targeting today (nov. 18) has been scrubbed and i'm not sure when the launch will be, we'll see how it works out with my now very busy schedule and other hobbies. the rocket is done-ish, but i'll probably do more with it in the meantime to make it a little more robust.
for this build, i wound my own fiberglass body tube, which was a first for me. it turned out well though i think. it has a 2 layer 45 degree 6oz fiberglass layup on the fins currently, but i'm considering re-doing the fin can in carbon fiber now that i have some.
RASAero sims say about mach 2.16 to 13,100ft with typical FAR weather conditions and the latest design iteration. allowing a +/- 10% error margin, this puts the rocket somewhere between Mach 1.94 with an apogee of 11,740ft and Mach 2.38 to 14,400ft. while i doubt the rocket will outperform the sims i suppose there is always a chance you get an over-performant motor and ideal weather.
the goal of the rocket is mach 2 and 2 miles high, and even with a 10% cut from the simulation result it exceeds 2 miles, but the speed does get down to Mach 1.94 if i take off the 10%, but if i get a result like that i might just have to pretend it said mach 2.
Avionics for the rocket are also homegrown because i want this whole rocket to be that (except the motor because EX motors scary + i'm Jr. L1 so i can't make them anyway), they are being done with some help from Walter Lohmueller. he's making a flight computer of his own that i will fly on the rocket, as well as my own altimeter. and just in case both of those fail, i'm thinking of having an RRC2+ as a backup to the backup.

I'll add pictures of the rocket here later if i remember to.