With a little help from my friends: 2-stage 54mm min diameter

[rocketace]

I was suggesting it as an idea to help keep your electronics cool as they were in a confined space inside of a dark NC, as that was what was being talked about.....

If this is a common problem I have missed, then I definitely need to look into it, but I have not heard of any case, besides cameras, where rocket electronics failed due to overheating (or its battery). Have you? I will ask some people I know that frequent desert type launch fields to get more points of data. I do know I have launched very similar set up many times in a 38mm NC in the summer out here in TX and I have never had an issue.

 

[OzHybrid]

Really like this thread. Showing all the configurations you considered and why you rejected them is much more valuable as a build thread than a straight here's what I built.
Thanks for taking the extra time.

 

[manixFan]

If this is a common problem I have missed, then I definitely need to look into it, but I have not heard of any case, besides cameras, where rocket electronics failed due to overheating (or its battery). Have you? I will ask some people I know that frequent desert type launch fields to get more points of data. I do know I have launched very similar set up many times in a 38mm NC in the summer out here in TX and I have never had an issue.

I have flown similar configs in the desert and at Airfest with no issues. Plus, the Blue Raven will report the temp via Bluetooth, so you can track it that way. You may have to do a bit of calibrating with it, but it should be reasonably close. Easy to test outside on a nice sunny afternoon.


Tony

 

[rocketace]

It's been almost a month, so time for another update.

Sustainer electronics is close to being finalized. Here is what the package looks like and its weighs in at 135g.



The booster electronic is also taking shape. Here is the 3D. There will also, be a Labratt Dual pull pin switch that will control both Ravens. For the GPS mag switch, I might try something fancy that Adrian himself posted about recently. The antenna for the GPS is removed from the model because this one has the wire whip antenna.




Here is the exterior coupler for the ISC. It's 6 wraps of FG with some red dye. I used the carbon tube as the mandrel with 0.002" mylar. It seams to fit really nicely so far. It's pretty strong, but I might end up redoing it with more layers or add 2 layers of FG sock to the outside.


This is a standard Wildman FG coupler below that will be the inner couplers for the carbon tubes. The biggest pain about custom tubes is standard parts wont work. This is how I sanded down the coupler so it would fit my carbon tubes.


Still so much to do.... Here is what is to come.
- Finish ISC electronics and bulkheads
- Test pack recovery gear several times to finalize space needed so I can cut the carbon tubes down.
- After the above are complete I can finalize the fins and start cutting them out.
- Play around with making high altitude ejection charges Tfish style.
- Glueing all the couplers to their parts.
- Making and mounting the fwd motor retention.


Here is what the RockSim is looking like so far. (the green tube is the actual motor lengths). The L1090 is scary far off, I'll see if I can adjust it in EngEdit.

 

[rocketace]

So I do not recommend this modification, and your results may vary, but I was successful in following Adrians modification to remove the terminal block and slide switch and replacing it with a magnetic switch.
https://www.rocketryforum.com/threa...switch-to-a-featherweight-gps-tracker.182193/

I used some side snips to carefully cut through the terminal block to remove the plastic, then its I was able to individually desolder each lead to remove it. Also using the side snips I carefully popped off the slide switch.


Then soldering some short leads for the GPS and battery followed by hot gluing the mag switch down I am left with the below!


This GPS will be for the ISC and here it is so far without any bulk heads.
The green and red wire at the top will go to the separation charge and the others at the bottom will go to the apogee/main charges for primary/backup booster charges.


I also got my 3/32" plate in for my fins and I am starting to wonder if I should have gone with 1/8".....

 

[rocketace]

Another month down and not as much progress as I hopped, but still progress!

For the ISC, there will be 3 tubes. The left one is the exterior coupler (still needs to be cut to size) and the right is the regular tube coupler that I sanded down with the drill above. The center is a section of FG airframe. This small section will take all the vertical load while the other two will take any bending load.



All the electronics will go in the area where the short section of regular airframe is so that it's RF transparent.



I also, did a quick test with a tfish style high altitude charge using vinyl tubing and 1g of powder. It's interesting to see in the last frame what looks like some powder getting ejected behind the flame and not burning. I will be doing some more tests to see if the length of tubing can fix that or not.

 

[rocketace]

Oh and I built some hot boxes!

First is a small box that is big enough to fit the fin can section of the rocket. The tube will have to stick out. But, I also heavy insulated the inside to I can also use it to anneal 3D printed plastic parts and not melt the styrofoam. Uses a variable settings heat gun that is plugged into a temperature controlled outlet that is good up to 120C. It was successful with running at 3hr at 120C, not including the 3hr ramp up and 3hr ramp down.



Along side this I also build a box for tubes that is not as well insulated, but temperatures will never be that high in this one. It's 12" square by 6ft long. Will allow me to use the same heating equipment as above and hook it up. I could fit a 8" by ~6ft tube, so should cover any future composite projects I have. I do plan to add some small fans inside this one to keep the air circulating better.


Thats it for now.
Y'all have a great Thanksgiving!

 

[JimJarvis50]

Another month down and not as much progress as I hopped, but still progress!

For the ISC, there will be 3 tubes. The left one is the exterior coupler (still needs to be cut to size) and the right is the regular tube coupler that I sanded down with the drill above. The center is a section of FG airframe. This small section will take all the vertical load while the other two will take any bending load.
View attachment 616266


All the electronics will go in the area where the short section of regular airframe is so that it's RF transparent.
View attachment 616267


I also, did a quick test with a tfish style high altitude charge using vinyl tubing and 1g of powder. It's interesting to see in the last frame what looks like some powder getting ejected behind the flame and not burning. I will be doing some more tests to see if the length of tubing can fix that or not.
View attachment 616269View attachment 616270View attachment 616271View attachment 616273View attachment 616272

Interesting on the powder being ejected. I assume you used 4F and had the ematch on top of the powder? A couple of dimensions that might be relevant are the ID of the vinyl tube and the length of the tube above the top surface of the powder.

Jim

 

[rocketace]

Interesting on the powder being ejected. I assume you used 4F and had the ematch on top of the powder? A couple of dimensions that might be relevant are the ID of the vinyl tube and the length of the tube above the top surface of the powder.

4F powder and the lighter was at the to of the powder. . Instead of an ematch its old match leads with some nichrome wire to keep testing cheap. Tube is 5/16" ID x 7/16" OD x 1.8" Long. 0.6" of dog barf on the bottom and 0.6" dog barf on top. I plan to do a few tests with various changes to see if there is any noticeable differences.

 

[davidb123]

4F powder and the lighter was at the to of the powder. . Instead of an ematch its old match leads with some nichrome wire to keep testing cheap. Tube is 5/16" ID x 7/16" OD x 1.8" Long. 0.6" of dog barf on the bottom and 0.6" dog barf on top. I plan to do a few tests with various changes to see if there is any noticeable differences.

I wonder if you'd get the same result if you tried a normal ematch? Since the ematch has pyrogen, a lot more heat is transferred quickly to the powder and over a larger area vs just a nichrome wire. Maybe that would help accelerate combustion?

 

[JimJarvis50]

4F powder and the lighter was at the to of the powder. . Instead of an ematch its old match leads with some nichrome wire to keep testing cheap. Tube is 5/16" ID x 7/16" OD x 1.8" Long. 0.6" of dog barf on the bottom and 0.6" dog barf on top. I plan to do a few tests with various changes to see if there is any noticeable differences.

For 1 gram of BP, the diameter seems fine. For the purpose of a high altitude charge, I would want perhaps 1.5" of open (or dog barf) tube above the top surface. At 0.6", maybe not enough tube to build backpressure.

Jim

 

[rocketace]

It has taken me a while to get back to this, but I have done a bit more testing for the ejection for the fun of it. All sticking with 1g of BP, but using 2 different tube sized (ID 5/16" & 9mm) and 3 different lengths (1.5", 2.5", & 3.25").

Each tube is made the below way:
- 3d printed bottom base that is super glued on
- Small section of packed dog barf
- 1 gram BP
- Small section of packed dog barf
- Rest filed with loose dog barf.
- Masking tape cap

I will start by saying having a sample size of one leave a lot of room for error, but it was still interesting. After looking at the slow-mo for a while I noticed that for all the 5/16" tubing had a decent secondary fireball and seams to take longer to burn all the BP. The 9mm tubing seamed to do a much better job getting the BP burnt up quick. For the different sizes 9mm tube the 2.5" looks to have a bigger smoke cloud, so I am guessing more got burnt. The long 9mm tube blew mostly out the bottom splitting the printed base and the tube wide open. Conclusions: Size matters, I think for a 1g charge a 9mm ID and 2.5"-3" length is a sweet spot where most of the powder gets burnt the quickest. Once I get the the point of doing actual ejection tests I will do a few more. The 1 gram is a guess how much I will need, but I am sure a bit of tweaking will need to happen.

Testing video: https://www.youtube.com/watch?v=VR0lnFL_E0c

Other than this, I have only made a little progress on this project other than cutting and drilling the ISC bulkheads using a 3D printed templet and test packing the recovery a few times.

Red disk on the left is the 3D printed prototype, the grey disk is the printed drill/cut templet, and the right is the fiberglass plate marked up using the templet.


This is the underside of the Aft bulkhead for the ISC. Everything is semi-permanently attached with hot glue.
The grey disk on the left will be permanently epoxied into the ISC and will provide a surface for the O-ring to highly seal everything.




40" TopFlight ThinMill chute packed with a cord cutter, nomex blanket, and kevlar harness into a 54mm coupler at 7.5". Current plan will be to leave 8.5" of recovery space to allow wires and quick disconnects room.

 

[rocketace]

Work, life, other projects (mainly a wireless launch controller) have kept progress slow here, but recently did a few things.

Figured out how I want to attach the recovery harness to the rockets. The motor retention bolt will have a washer & spacer. The kevlar will be in a printed circular housing that lets it spin around the spacer so that it wont back out the bolt. Parts were 3D printed to test, but the plate will be FG and the spacer will be aluminum.



Also, The carbon tubes have been cut to length, some dry fit testing, and glued in the motor bulkhead to the booster.


Above the motor bulkhead is a small ring that gets glued in with it just to give it more surface area to glue to the tube.

 

[kjhambrick]

That rotary disk attachment for your ( beautiful ) Kevlar loop is pure-genius, Jason !

I was never comfortable with the idea of rod-end bolts in the threaded forward closure ... thanks for the new idea !

-- kjh

 

[rocketace]

That rotary disk attachment for your ( beautiful ) Kevlar loop is pure-genius, Jason !

I was never comfortable with the idea of rod-end bolts in the threaded forward closure ... thanks for the new idea !

-- kjh

Thanks! I have yet to find something that I liked for a minimum diameter, but so far this seams to work even under a bit of load.

 

[kjhambrick]

Nice !

I can 'see' it working

I've been making Brummel lock-splice loops since I saw the technique on You Tube -- no stiches necessary and they won't let go !.

I meant to post this link: Brummel lock-splice with one side fixed -- your loops look like the same !

-- kjh

 

[rocketace]

Thats the one! I use a Brummell lock splice on all my loops and have never had any issues with it yet (Rocket and camping). That specific link you posted is mainly if you're not able to pass the tail end though. Still good, but you have to take the extra step of taking the twist out. Here is their video to follow if one side is not fixed. I use this one for both ends. It's a bit snug to fit the first loop though, but it works.