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Update time!

I have been quite busy with life stuff the past couple weeks so the rocket hasn't gotten much attention, but since I said I will do i build thread ill update what I have done.

I finished most of the Electronics bay and wiring, i might rewire the switches with some thicker gauge wire because the isolation got a little gross, its not bad but not perfect and id like it to be.

Body tube has been cut to length and the coupler is bonded to the forward end. nothing fancy here, just sanded, degreased and bonded.

I bonded the allignment/retaining ring in the body tube most recently. Getting this stupid ring in correctly was a huge pain, im not sure how i could do it differently, maybe make some kind of jig to hold it at the correct depth but im not sure. This rings isn't load bearing but it clocks the electronics bay in the body tube so that the vents/ports will align with my screw switches.

now for some pictures! everyone likes pictures!

everything is wired up and mounted, the wires where passed back behind the sled and then forward again to the altimeters.
wire detail.jpg

Wires potted into the FWD bulkhead to stop any wiggling
potted wires.jpg

Terminals glued in!
potted terminals.jpg

Switch detail, soldering is kinda gross :(
switch detail.jpg

Retaining ring bonded in, the heads of the 1/4-20 socket head screws that hold the electronics bay together fit in those holes snugly making for a perfect alignment to the vent holes every time!
retaining ring.jpg

The E bay gets pulled down snugly as I screw the motor in, this mark just tells me which side goes where but the retaining ring does all the alignment.
sinched down.jpg

Electronics bay is firmly held down by the motor's closure and this is how I plan to girth hitch the recovery tether. hole you see is for a shear pin.
girth hitched.jpg
 
Hi Slaak. Nice build!

One thing to watch is your recovery harness angles there. You might want to make the angle of where those two parts of your harness meet to be much more acute.
girth%20hitched.jpg

As it stands you are multiplying the forces applied to the vertical piece by a considerable number onto the angled piece. If you arrange for the meeting point to have less of an angle between you will reduce the stress on the harness at deployment.

For an explanation as to why this multiplication of force (reduction in load capacity) happens (it's a trigonometric thing), google "sling rigging angle chart", or have a look at this link.
https://www.fdlake.com/rig-slng.html

Keep up the good work!
 
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This is a prime example to remind me .. That im so far away from anything like this..

Amazing..

Cant wait for updates !!!
 
Though you said it in previous posts, I just realized that you are mounting the AV bay directly to the forward closure of the motor. So are you planning to do traditional dual deploy, or are you just going to pop the chute at 33k ft? You said tumble recovery at apogee; do you mean you are going to use a Jolly Logic Chute Release or something similar? Sorry, I'm just probably missing something here.
 
Though you said it in previous posts, I just realized that you are mounting the AV bay directly to the forward closure of the motor. So are you planning to do traditional dual deploy, or are you just going to pop the chute at 33k ft? You said tumble recovery at apogee; do you mean you are going to use a Jolly Logic Chute Release or something similar? Sorry, I'm just probably missing something here.

I *Think* he is going to pop the body tube at apogee, let it tumble until it hits X amount of feet THEN deploy the Main.
 
Hi Slaak. Nice build!

One thing to watch is your recovery harness angles there. You might want to make the angle of where those two parts of your harness meet to be much more acute.
View attachment 325185

As it stands you are multiplying the forces on the vertical piece by a considerable number. If you arrange for the meeting point to have less of an angle between you will reduce the stress on the harness at deployment.

For an explanation as to why this multiplication of force (reduction in load capacity) happens (it's a trigonometric thing), google "sling rigging angle chart", or have a look at this link.
https://www.fdlake.com/rig-slng.html

Keep up the good work!

That's a great catch! that is something I always try to drill into peoples heads when I've taught anchor building for rock climbing, its very easy to create thousands of pounds of tension in the webbing if those angles are the way I have it in the picture. Its that way in the pictures because, well I was being lazy haha. In flight configuration im actually going to feed the loop through the other direction and have the hitch cinched down to where it comes out of the bulkhead on the left side (left in the picture) to keep it away from the antenna. Doing it that way will make the choke angle 180° so I should get the full strength of my webbing (no force multiplier according to this link https://www.fdlake.com/rig-slng2.html#choker) if I am thinking about this correctly.

This is what I mean by cinched down (more or less)
Anchors-Single-Girth-large.png
 
I *Think* he is going to pop the body tube at apogee, let it tumble until it hits X amount of feet THEN deploy the Main.

That's is correct, I guess I haven't really given a very good wide view picture yet. Im planning on popping the nosecone at apogee, I have a small bulkhead that will cap the blue tube and hold the apogee charges. the main parachute will be in the highlighted portion of the picture below and the two eyeball looking holes in my forward bulkhead will hold charges that will eject the main. I haven't made it yet but there will be some kind of piston head type part that will be between the charges and the main parachute.


appoge charge holder.PNG
This will cap the blue tube holding the apogee charges.

blown up.PNG
cross section of the front end, main parachute will be in the highlighted area.
 
I'd expect that this scheme will yield a stable rocket during descent. Will you be using a drogue to destabilize?
 
That's a great catch! that is something I always try to drill into peoples heads when I've taught anchor building for rock climbing, its very easy to create thousands of pounds of tension in the webbing if those angles are the way I have it in the picture. Its that way in the pictures because, well I was being lazy haha. In flight configuration im actually going to feed the loop through the other direction and have the hitch cinched down to where it comes out of the bulkhead on the left side (left in the picture) to keep it away from the antenna. Doing it that way will make the choke angle 180° so I should get the full strength of my webbing (no force multiplier according to this link https://www.fdlake.com/rig-slng2.html#choker) if I am thinking about this correctly.

This is what I mean by cinched down (more or less)
View attachment 325189

I said it was needed to be fed threw the other direction in this post, that's incorrect. it should be fed threw the direction I have it in the picture but cinched down to the left as I have masterfully drawn here.
fwd bulkhead.PNG
 
I'd expect that this scheme will yield a stable rocket during descent. Will you be using a drogue to destabilize?

This was brought up by my TAP as well. I don't have a good answer for this yet, I haven't made a rocket with this configuration exactly so I'm not sure where the cp will be sans nosecone. I'm going to try and sim the rocket without a nosecone to see if it is stable still. I don't really want to use a parachute for a drogue because I cant think of a configuration that I can ensure deployment with the amount of space I have left. I have been toying with the idea of putting a nylon streamer of some kind on the tether that will hold the nosecone. I don't know how to verify my idea at this point but my gut tells me that a steamer and my nosecone flapping in the wind should be enough drag to break the ballistic trajectory if my rocket isn't way overstable.
 
This was brought up by my TAP as well. I don't have a good answer for this yet, I haven't made a rocket with this configuration exactly so I'm not sure where the cp will be sans nosecone. I'm going to try and sim the rocket without a nosecone to see if it is stable still. I don't really want to use a parachute for a drogue because I cant think of a configuration that I can ensure deployment with the amount of space I have left. I have been toying with the idea of putting a nylon streamer of some kind on the tether that will hold the nosecone. I don't know how to verify my idea at this point but my gut tells me that a steamer and my nosecone flapping in the wind should be enough drag to break the ballistic trajectory if my rocket isn't way overstable.

The popular "HED" system making the rounds now involves deploying the cone+altimeter bay assembly. The cone, chute, electronics, and coupler represent the entirety of the fore mass of the rocket. By deploying that you get a very large swing in CG toward the aft, therefore destabilizing.

Your design separates almost no mass at all, leaving the chute, electronics, and bay weight (which will be substantial being all aluminum, FG, and Nylon/Kevlar). The mass of the propellant is gone at burnout, pushing your CG even further forward. I'd bet that your rocket would successfully fly in a stable matter without the cone shell in place. I think it's almost certain to follow a ballistic trajectory without a drogue.
 
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That's a great catch! that is something I always try to drill into peoples heads when I've taught anchor building for rock climbing, its very easy to create thousands of pounds of tension in the webbing if those angles are the way I have it in the picture. Its that way in the pictures because, well I was being lazy haha. In flight configuration im actually going to feed the loop through the other direction and have the hitch cinched down to where it comes out of the bulkhead on the left side (left in the picture) to keep it away from the antenna. Doing it that way will make the choke angle 180° so I should get the full strength of my webbing (no force multiplier according to this link https://www.fdlake.com/rig-slng2.html#choker) if I am thinking about this correctly.

This is what I mean by cinched down (more or less)
View attachment 325189

For the lifting sling setup the forces are multiplied by the geometry of the sling. The vertical force is on one side of the triangle, and the hypotenuse has a higher load.
imgE.jpg

Choker hitches have their own derating requirements.
Load-Angle-Chart.gif
 
Update time!

The rocket is pretty much done. range test on my GPS went well, I left the rocket on a small hill and drove 10 miles until i ran out of road and was still getting signal, no reason to think it couldn't go further. Ejection charge tests shot off the nose cone and the parachute cannon for the main worked great. Im trying to come up with a better way than using tape to hold the powder in my charge wells, I think there is a good chance of sympathetic ignition of the backup charge with just using tape, I have a couple ideas to test out this weekend to make it all work a little better. All that really remains is going over the surface with some 2000 grit to make it all shiny.

I put a couple days in this last week and designed/buit a launch tower for the rocket. I used mostly 80/20 because i had a bunch sitting around getting dusty from an old project that never ended up happening. I tried to design it so that i could unassailable it and put it together at the field if needed. technically i could do that with the way it turned out but there is no way id wish that on anyone, it would be a couple hour task and id rather not do that at black rock.
launch tower.jpg

I put together a test fin/body tube section to test out my fin mounting method and give me a little more confidence that my fins wont rip off mid flight. The tests went pretty much how i expected and at the moment im feeling pretty confident with the design. I haven't been able to pin down exactly how much force is going to be exerted on the fins during flight. Openrocket says the peak drag force on my rocket will be 70lbs, im guessing most of that will be on the nosecone, but regardless im not really worried about regular drag force ripping off the fins. I think the most stress on the fins will be a sort of rotational + cantilever stress when they are correcting the rockets flight path if it gets wiggly in the air. Luckily my stability margin is pretty good, so the rocket shouldn't try to diverge in direction too much ( I think?). Anyways I did three test trying to rip off my test fin. one pulling straight back along the rockets length, one pulling the fin out away from the airframe, and one imparting a rotational/cantilever force on the fin. The test load was me, roughly 180 lbs dressed, not very scientific but im the heaviest thing that I have sitting around the house... going into the test i fully expected the first two tests to work out just fine and expected the bond to fail on the third test. To my surprise the fin held on for all three tests, including the nasty twisty/bendy one. The only problem encountered was that my table tiped over on me spilling my rocket on the floor as soon as i lifted off the ground on the last test.

That was a gross amount of rambling so here is some pictures to try and make up for it.

vert hang rocket.jpg
hang orientation for the first test.

vertical hang.jpg
Test one. Note: motor tubes are kind of hard to hold yourself up on when your worried they may break off and smack you in the face.

dead hang.jpg
This test was considered a success after 5 pull-ups where completed.

twist 1.jpg
view of twisty test setup.

twist 2.jpg
view 2 of twisty test setup.

twisting test.jpg
This test kind of worried me because I fully expected it to fail after 100 pounds or so. Good news: the fin held the twisting moment just fine. Bad news: my foot is starting to touch back down in this picture because my table was tipping over on me and spilled my rocket on the floor about half a second later. (I was concentrating my weight roughly 1 foot from the center of the fins root cord.)
 
Nice work - it happened, there are photos!

I was a little worried about that tripod being between your knees on that pic being the larger of the risks... ;-)
 
Hi Slaak,

I'm not sure how I missed your thread. You've done some amazing work. I have some input on your design.

1. Nice mill. G0704, right? That's what I have. I added ball screws, a 1:1 belt drive and 1100W motor among other upgrades. Here's a link to my build thread if you're interested:
https://www.cnczone.com/forums/benchtop-machines/166317-cnc.html

2. I'd be very hesitant to fly this rocket without a drogue or streamer. The NC isn't going to provide enough drag to slow it down and it's very unlikely to tumble. You should have enough room left over in your NC for a small drogue. I'm using a 12" Fruity Chutes elliptical. You only need about 1" x 3" to pack it into.

3. I've used aluminum tape on my machined bulkhead charges. It seals well enough that you shouldn't have to worry about the backup charges going off.

4. Your fin attachment looks stout to me. Nice job.

5. Is this a XPRS or BALLS flight?


Chris
 
The alignment ring is glued into the booster below the aft bulkhead, right?

What is your assembly sequence? How are you going to bolt the aft bulkhead to the motor with the electronics trays in place?
 
Hi Slaak,

I'm not sure how I missed your thread. You've done some amazing work. I have some input on your design.

1. Nice mill. G0704, right? That's what I have. I added ball screws, a 1:1 belt drive and 1100W motor among other upgrades. Here's a link to my build thread if you're interested:
https://www.cnczone.com/forums/benchtop-machines/166317-cnc.html

2. I'd be very hesitant to fly this rocket without a drogue or streamer. The NC isn't going to provide enough drag to slow it down and it's very unlikely to tumble. You should have enough room left over in your NC for a small drogue. I'm using a 12" Fruity Chutes elliptical. You only need about 1" x 3" to pack it into.

3. I've used aluminum tape on my machined bulkhead charges. It seals well enough that you shouldn't have to worry about the backup charges going off.

4. Your fin attachment looks stout to me. Nice job.

5. Is this a XPRS or BALLS flight?


Chris


1. It sure is. I got it last fall and did a CNC conversion on it right away, looks like we have a lot of the same electronics and some of those pictures in your build thread look familiar so I think I read threw that some years ago. I havent done the belt drive conversion/motor upgrade on my spindle yet but thats in the plan for this winter most likely, the 2200 RPM max is killing me. Still need to build a proper enclosure as well. I have a stock G0602 as well for all my turning work that is a pretty handy little lathe as is but id like to make some nose cone mandrels so I think im going to work on CNCing it this fall.
shop.jpg

2. It has a parachute in the nose now. Not sure why I originally didn't want to include one but I think you are right and I will be much better off with a drogue than without. The chute in there now is just 2' rocketman that I had sitting from another build but there is a 12" and 16" fruity chutes in the mail that I will likely replace it with.

3. I think I fixed the problem I was having since that last post. It wasn't really the tape I was doubting I just couldn't get the ematches to fit in the charge wells and was getting a crap seal around the charge wells due to the bulging ematch+wire. either though a brain fart or mistake I made early on I made my charge wells way too shallow for the ematches I have, they where supposed to be .5" deep but where .375" for some reason... opps. anyways I remade the bulkhead that holds my apogee charge last weekend and its all peachy now.
unnamed.jpg
unnamed (1).jpg

4. Thank you, I'm pretty happy with how it turned out. I think if I had to do it again though I probably would of laid down some Kevlar tow under the glue fillets to add some extra strength and help distribute the load a little better. I hadn't posted an update on here about it but after the test I posted about I cranked on the fin until it broke free and from the way the glue fillet fractured it doesn't look like this epoxy can really distribute the force without some kind of fiber mixed into its matrix, but I guess that should kind of be expected. Still, I think with the added glue fillets I did it should help dampen any vibrations.

5. I'm just going to BALLS this year. I haven't actually been to XPRS yet but I will probably be going to both in the future.



The alignment ring is glued into the booster below the aft bulkhead, right?

What is your assembly sequence? How are you going to bolt the aft bulkhead to the motor with the electronics trays in place?

That's correct, the alignment ring is glued in there. I'm out of town this weekend so I cant take any pictures but the assembly sequence is pretty slick I think, that's one of my major gripes with some rockets ive made in the past and wanted to make it as easy as possible with this one.

  • First going to pore the charges in the forward bulkhead and wire those.
  • Then bolt on the parachute cannon that holds my main and pack the parachute
  • place the apogee charge holder on the end of the tube and shear pin.
  • pour the apogee charges and wire it up.
  • Ill probably take it to the field at this point since the rest only takes a minute or two
    front.PNG
  • out at the launch pad plug in the electronics and attach the drogue+nosecone harness
  • forward assembly gets placed in body tube with the 1/4-20 socket heads slotting in the alignment ring.
    install mode.PNG
  • motor gets put in the aft end and tightened/screwed in when it reaches the 3/8 bolt going through the aft bulkhead. Tightening the motor in pulls the electronics bay all the way tight into the body tube and seals it off with the o-ring around the forward bulkhead.
  • nosecone goes on + shear pins
  • rocket in the launch tower + electronics turned on.
  • igniter in and launch!
 
If you do a belt drive conversion I recommend having high and low ranges with 4500 and 2200 rpm max. Sometimes you need to using a slitting saw or face mill at lower rpm and you wind up with a lot less usable power at those ranges. I still keep thinking that I need to buy another drive pulley and belt for the occasions that I need more torque.

Everything in your last post makes sense. Good luck with your flight.
 
10 miles on the 100mW BLGPS is pretty darned good. It looks like the tracker is carried inside the CF tube with the tracker antenna thoughtfully placed in the FG nosecone. I take it the GPS can get a sufficient lock from within the CF confines?
Kurt
 
If you do a belt drive conversion I recommend having high and low ranges with 4500 and 2200 rpm max. Sometimes you need to using a slitting saw or face mill at lower rpm and you wind up with a lot less usable power at those ranges. I still keep thinking that I need to buy another drive pulley and belt for the occasions that I need more torque.

Everything in your last post makes sense. Good luck with your flight.

That's makes sense about needing to keep the low end torque, I have a fly cutter that I don't really want going to 4k rpm haha. Depending on time & money I may just order the belt drive kit from benchtopprecision.com. looks like they say the low end maxes out at 2800 and 5000 for the high, probably good enough.
Thank you and good luck on your flight as well!


10 miles on the 100mW BLGPS is pretty darned good. It looks like the tracker is carried inside the CF tube with the tracker antenna thoughtfully placed in the FG nosecone. I take it the GPS can get a sufficient lock from within the CF confines?
Kurt

That is correct. I was a little worried about the GPS antenna being inside the carbon body tube at first but it hasn't shown to be a problem yet, no problem getting lock while on the bottom floor of my house when its in the rocket even. The GPS antenna sits right about where the FG coupler tube stops and the carbon tube starts, im not sure what kind of view factor the antenna needs but I guess its got enough?
 
The GPS antenna sits right about where the FG coupler tube stops and the carbon tube starts, im not sure what kind of view factor the antenna needs but I guess its got enough?

Is the carbon below it or above it when it is going up or coming down? That will affect time to lock and how well it holds the lock. Can you experiment with positions to simulate the flight? Also, a limited view of the sky can make for slightly higher position errors. This can be particularly sensitive the the constellation positions at the time.
 
Looks like its time for a post BALLS update.

This was my second time going to BALLS and minus a little food poisoning accompanied with 2am puking on the playa it was a great time!

I rolled up in my cramped car Thursday afternoon and caught up with everyone from back home. no rocket work thursday.
Only took about 20-30 minutes of work in my make shift shop Friday morning to build and wire the ejection charges, after that and a quick pack of the parachutes the rocket was pretty much ready to go.
setup.jpg
Im very happy with how that part of the rocket turned out, I started flying rockets up in Alaska. Up there we always fly in the winter on frozen lake beds, so having a short prep time is super important if you value feeling in your hands. I could of built the charges at home and total prep time at balls would of been just plugging in the battery and screwing in the motor, but I figured id have enough time and wanted to show off the rocket a bit without live charges in it.

Ended up spending the rest of Friday and Saturday morning helping a friend with 2 stage project that ended up going a pretty respectable 96k ft. Nice job Noah!

While i was out at the away cells my tower was mistaken as a club pad and got adjusted for a much skinnier rocket, so I had a spend a bit of the afternoon readjusting the tower to my rocket. The flight was pretty wiggly out of the gate, I think a big part of that was due to me not taking enough time to properly readjust my tower. As a result the rocket was pretty loose in there, especially near the top of the tower. Wish I would of done a better job but now I know for next time.
second frame.jpgreal second.jpgsquigly.jpg

After the rocket finished doing its S turns it took a wide arching path back towards town and topped out around 25.3k. Im not sure what caused the arch (wind, rocket design, bad start, or luck?) but it ended up costing a lot of altitude. From what I can tell looking at the GPS data, apogee was about 3.5 miles down range.
gps flight.jpg
(up on left down on right)

Gotta say though I absolutely love the BigRedBee GPS, from Apogee until just a few hundred feet above the ground I was getting good packets with just my handheld radio, would probably of never seen the rocket again without that tracker.

Parachute deployment went off without a hitch as far as I can tell, velocity data from the altimeters shows a consistent 75ft/sec from the moment of apogee and 32ft/s under the main, looking at the graphs closely it looks like it took only about 50 ft for the main to inflate.
altimeter 1 pic.PNG

Recovering the rocket was a piece of cake, thankfully it was still well on the playa and about 5.5 miles from the flight line. So we just got a heading from the kenwood and zoomed off.

It came down on a surprisingly hard section of playa, the stuff felt like cement under foot. I think it landed on a combination of aft closure + fin. Thankfully, probably mostly on the closure. But where the fin hit it looked like someone took a good swing with an axe to the playa and there was a thin 3" deep hole where the fin cut in.

Anyways this is how we found it, hadnt moved an inch since touchdown.
first sight.jpg

DSC_1481.jpg

I am super happy with how this project has turned out, other than the not so straight flight which may or may not of been under my control, everything went exactly as planned. The rocket came back with some victory dirt but not a notable scratch on it.

Not sure if I will fly this rocket again or not at this point. I think since it was my cert rocket, I am going to at least try to keep it in once piece and not salvage too many parts from it.

Id be happy to answer any questions if anyone is curious about the project and hopefully ill post on here a little more in the future and have something interesting for next year.

Not sure if I can upload .pdf's here but here's a small packet about the project. A lot of info in there may be out of date or inaccurate so don't be surprised by some inconsistencies.
View attachment Doc1.pdf
 
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