Blue-J: J510 Submin to Mach 2.5 and 20k ft @ TRAPHX or BALLS 2024

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Iupiter1007

New Member
Joined
Feb 4, 2023
Messages
3
Reaction score
10
Location
Phoenix, Arizona
Hey everyone! I've been getting inspired by the forum for a while now (thanks y'all for your incredible work and talent) as well as the r/rocketry discord server. I've been slowly working on this submin for several months and figured it would be good to share! I have my TRA L1 and L2 certs, and flew an L1000 to 16,000 ft. last October.

My goal for this project was to learn more about really high performance flights and optimization, with a priority of a really solid structural design. Here's the OR:
1719764302326.png
The fins have a strange cant to the tip chord since I printed it out of Aluminum through JLPCB, and faced similar warping to @Neutronium95's Bare Minimum fincan. It's almost a downscale of his fincan, very similar overall part geometry. I conducted flutter analysis in FinSim and decided on a 0.09" thick biconvex profile:

1719780215261.png1719780525979.png1719780575987.png

They have a big tip chord to improve CN_alpha and hopefully reduce movement of Cp as the rocket goes supersonic through M2.5. The other parts are a printed coupler (ditched for reasoned explained below) and a cute printed eyebolt (ditched because it was scary thin, in theory it could support recovery loads but I hated the integration procedure).

New AVbay is a fiberglass sled with 1/8" kevlar cord running through holes. Recovery is via a 15' thin mill chute with a 6" nomex and cable cutter. This is then covered in another 6" nomex. The outer 6 or 9" nomex is a "drogue" deployed when a vinyl tube charge fires. Then main is by cable cutter deployment.

I had considered retaining the main by friction fit like Kip's MESOS and Aeropac, but I'd prefer the cable cutter method, it also uses less kevlar cord. Old diagram pictured below.
1719768794918.png
TLDR of the old stuff: Be realistic about wiring etc, and actually consider integration procedure, not just if stuff fits together in theory.

______________
OLD DESIGNS:
So you guys have an idea of the analysis paralysis I put on myself and performance brainrot I faced, here is the original OR file from last October: 1719764534595.png
Soo yeah, lots of changes haha. I switched to a submin since I thought it would be fun. I decided to send it for the J record because it would be a learning experience, boy it was. Here are some of the silly AV bay designs I came up with as the design iterated:
1719764875298.png1719764826341.png1719780265239.png1719780359162.png1719768625767.png
Originally dual redundant with EZmini, Blue Raven, Featherweight, and RDF Beacon (successful config I flew in my L1000).
Then my BR was destroyed in a flight accident (RIP) and I switched to a Fluctus and RDF.
To save space I switched to EZmini and RDF only for a while (NO GPS to 20k plus).

I tried printed this design, a little too optimized and later ditched this whole 3d printed ebay. The goal was to route recovery loads directly through the eye bulkhead and through 4 4-40 screws to the nosecone. Here is how the packing diagram was, inspired by Aeropac's 100k SSDD and Kip's MESOS, but smaller.

1719768894064.png

For high altitude deployment I've seen that it's important to contain your BP and ensure your ematch is placed so as the BP combusts, it tries to fly out of your vinyl tube/ charge cannon but the ematch is above the BP, ensuring more complete combustion. So, I integrated a charge well in my 3d printed coupler, but I designed it late at night and forgot to make it interface well with the AT fwd closure, so I lathed a coupler to interface between the fwd closure and the printed bit. Here's some progress on it:
1719768565123.png1719768729907.png
I epoxied it in, but added too much and the closure stopped fitting. So that's ditched. Now I'm machining a whole new one.

I made a 7:1 VK nosecone out of 4 layers of soller sleeve (after an unnamed number of attempts, maybe 6 failed mandrels, and a new 3d printer (Bambulabs are cool besides the recalls):
1719768504003.png1719780918741.png
smoothed cone.jpg
I realized the nosecone didn't give me enough space, so I ditched it an went with a lower fineness nosecone (6:1) and lengthened the straight section from 2" to 6."
 

Attachments

  • 1719767541309.png
    1719767541309.png
    195.4 KB
  • 1719768396152.png
    1719768396152.png
    14.3 MB
Last edited:
Looking good! Hope the flight goes well. What TRAPHX launch might this go up at?

I'm slowly working on some stuff to fly there, but job and family have been getting in the way of rockets :p
I tried to make it there earlier this year, but stuff came up.

I have the 38/1320 case (and the Loki 38/1200) for a similar style rocket, but will probably go min dia, rather than submin.

Good luck!
 
Looking good! Hope the flight goes well. What TRAPHX launch might this go up at?

I'm slowly working on some stuff to fly there, but job and family have been getting in the way of rockets :p
I tried to make it there earlier this year, but stuff came up.

I have the 38/1320 case (and the Loki 38/1200) for a similar style rocket, but will probably go min dia, rather than submin.

Good luck!
I understand that haha (I started working on this last November and planned to launch in late january lol), schedule slipped and I got busy as a college student.

Plan is, well, BALLS 2024, or the October TRAPHX date. I also have some other projects on the backburner but those are to chat about at a later time, I'll just say K2050 MD with 100G+ accel . . .

Also I've had the J510 and K2050 integrated since January, may need to lightly expose new AP on the grain faces since it's been a while, unsure though.
 
Hehe, I have a 'back burner' project as well involving the K2050 staging to an I1299... I have an odd mix of 'safe and sane' rockets, as well as high performance stuff. Most of what I fly is mid power, as I can really only make it to one or two 'big' launches a year.
 
I understand that haha (I started working on this last November and planned to launch in late january lol), schedule slipped and I got busy as a college student.

Plan is, well, BALLS 2024, or the October TRAPHX date. I also have some other projects on the backburner but those are to chat about at a later time, I'll just say K2050 MD with 100G+ accel . . .

Also I've had the J510 and K2050 integrated since January, may need to lightly expose new AP on the grain faces since it's been a while, unsure though.
The J510 is a great motor. My avatar is a J510 in a ShadowAero Raven 3 at BALLS in 2022. Once you build the motor, if you keep the solid red plastic cap over the nozzle and are using a plugged forward closure, the grains should be ok for quite a while. I've flown motors that were built and then not flown for up to 3 years without trouble, but I do use pretty hot ignitors.

When I was working on 38mm MD rockets, I found that the lower overall weight and better mass fraction of the CTI J530 gave me slightly better altitudes. But I had to epoxy an aluminum nut (with JB Weld) into the charge well to emulate the threaded closure of the Loki/AT motors. Not a big deal, but I suppose that would disqualify it as a commercial motor.

Looking at your design and the stuff done by @Adrian A, it reminds me on why I finally quit trying to go for a record – I needed much smaller hands! After a while, working in such confined spaces where every cubic centimeter is used and every extra gram matters just gets to be an exercise in frustration.

Good luck on your project and post some updates!


Tony
 
Looking at your design and the stuff done by @Adrian A, it reminds me on why I finally quit trying to go for a record – I needed much smaller hands! After a while, working in such confined spaces where every cubic centimeter is used and every extra gram matters just gets to be an exercise in frustration.

Tony,

I'm in the same boat as you with that. I strive to break my own personal records on altitude and speed. I don't have the level of detail and skill that those other guys have. It stops becoming fun if you get frustrated constantly.
 
1739383170579.pngHey everyone! I've been quite busy with college and my club's rocket team, so no time for updates. I got everything prepped and flew this at TRAPHX in January. However, there was a motor failure partway up, leading to a CATO. Leading theories are that it was just an unlucky failure, or possibly the closures weren't tightened down all the way (though I doubt this). There was no major rattle in the motor or anything before, and we followed the instructions when it came to integrating the motor as well, currently in discussions with AT's warranty department. Pad footage: https://photos.app.goo.gl/kkqEvFCbg9Bv2Mkx6

On the bright side, all aerostructures above the motor held and all avionics came down softly and can be reused. I used a chute cannon approach, friction fitting the main in the nosecone which worked nicely. The kevlar for the main came through one side of the AV bulkhead, and the other longer line attaching to the motor coupler was on the other side. I separated them as much a I could, and had them come out of 2 sides so recovery forces would pull the kavlar taught and hopefully not pull the main out at apogee.
1739383397697.png

I'll link to more photos here: https://sites.google.com/view/marzukhasan/blue-j-j-impulse-altitude-record-attempt?authuser=0

Thanks to everyone on the forum, I learned a lot looking through others' high performance build threads in selecting fin shapes etc! I used 0.1" thick biconvex aluminum fins, which appear to have worked nicely during flight.
 

Attachments

  • IMG_4341.JPG
    IMG_4341.JPG
    2.6 MB
  • IMG_5511 2.jpg
    IMG_5511 2.jpg
    4.6 MB
  • IMG_5247.JPG
    IMG_5247.JPG
    1.2 MB
  • IMG_5248.JPG
    IMG_5248.JPG
    3.8 MB
  • IMG_5490.JPG
    IMG_5490.JPG
    2.3 MB
  • IMG_5491.JPG
    IMG_5491.JPG
    4.6 MB
  • IMG_5495.JPG
    IMG_5495.JPG
    2.8 MB
  • IMG_5496.JPG
    IMG_5496.JPG
    3.5 MB
  • IMG_5499.JPG
    IMG_5499.JPG
    2.6 MB
  • IMG_5501.jpg
    IMG_5501.jpg
    3.7 MB
  • IMG_5503.jpg
    IMG_5503.jpg
    522.5 KB
  • IMG_5504.JPG
    IMG_5504.JPG
    3.6 MB
Last edited:
Really painful when all that hard work is thwarted by something like a CATO. Thanks for posting the follow up and keep up the good work and information.


Tony
 
Back
Top