Estes Vagabond - 38mm Minimum diameter

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1st ground test tonight.

BlueJay Flight computer, 0.3g charges for drogue and main.

Apogee charge was somewhat successful. Charge went off and separated with authority, but did not pull all the line out of the masking tape wrapped harness. This shouldnt be a problem going forward as I probably wrapped it too tightly. A line in the pre-flight checklist should prevent this in the future.
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I always forget I have to completely kill the app between ground tests.

Main charge was a problem. I could see it blow inside the coupler, but it did not separate. This is a VERY tightly packed volume and only a single #2 shear pin.. and when I say packed tightly, I mean Im afraid I may have bent the poly nosecone from the INSIDE. 10ths of a gram are hard to manage, so while I may want to inch up in small increments, I think i'll have to settle for 0.5g next time.
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I will still use the rubber glove finger, but will leave some of the heavily taped off parts of the support. Recovery room in this rocket is so premium, I might just try to redesign the AV bay for another 1 or 2 milimeters.
 
Was thinking about using flyaway guides, but they wont arrive in time for launch day.

So 3d print some rail guides and epoxy to airframe
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I liked the idea of fly-away guides, but I tried one and had it hang up on the fins of a rocket that didn't have enough sweep. Two flights in a row were "off-nominal" and I scrapped the airframe because I couldn't repair it. Made me more of a tower person. I don't want to have to guess whether the fins of any given rocket have enough sweep to be 100 percent the guide won't hang up on them. I think the fins on your Vagabond are in the maybe-maybe not zone.
 
I’ve been planning to use a LOC 1.6-inch coupler in my Wildman 1.6-inch fiberglass airframe with an I200. It has a fiberglass nose cone. Is this a recipe for destruction?
I don't wanna hijack the thread, but i would at least put a layer of fiberglass inside the LOC coupler. A 1.6" 'glass rocket on an I200 isn't super extreme, but the stock LOC couplers aren't very strong, unreinforced.
 
Finished ejection testing:

Decided to change electronics from Eggfinder Mini and Blue Jay in separate containers and switch to Eggtimer Quasar + Telemetry Module.

THis will require a couple more inches of AV bay to allow for the antennas.
 
I’ve been planning to use a LOC 1.6-inch coupler in my Wildman 1.6-inch fiberglass airframe with an I200. It has a fiberglass nose cone. Is this a recipe for destruction?

If your talking LOC 38mm tube couplers , it depends on how long it is. Certainly longer then 2 inches is needed 🤣

An I200 is not that bad a motor, I flew an I205 twice in a 2.5" Estes Partizon and the couplers were not even glued together, friction fitted for shipping.

Edit: I am trying to remember if the coupler/bulkhead on my un-glassed 38mm Loc Tube rocket on a J570 was glassed inside for the mini av/bay? I probably did, as I was putting a thin sheet of fiberglass with finishing epoxy on the inside of 2.6 LOC couplers with Stiffy tube. I used party balloon to hold the fiber into the coupler insides while the epoxy was drying
 
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If your talking LOC 38mm tube couplers , it depends on how long it is. Certainly longer then 2 inches is needed 🤣

They are 5 inches long. I pulled a photo of a Jim Jarvis build into AutoCAD and worked out that he had used a coupler insertion length of ~1.67xD, so that's what I've been using as a rule of thumb. For 38mm, that's about 2.75, which leaves 2.25 of the LOC coupler to glue into the glued side, more than enough. I haven't dug one out and measured the wall thickness of the coupler yet, but Apogee lists it as:
  • Inner Diameter: 1.398" (3.55 cm)
  • Outer Diameter: 1.520" (3.86 cm)
That gives a thickness of 0.061, which I reckon should be plenty. Estes 2.5-in couplers are only 0.035.

Also, I have a pilot tool to sand perfectly square and flat ends on tubes, so the fiberglass will be mated as well as it could be. And the Intimidator Mini only has a 22-inch tube, so it won't have a ton of bending moment. But yeah, maybe I'll throw a layer of 6-oz glass inside the coupler.
 
Neat thread, I'm enjoying this. Makes me think back to when John Buckley got his L1 on an Estes Big Bertha with a AT Single Use H124J motor. He did get his certification on that flight. It was pretty neat to watch!

You mentioned your tube not being as stiff as the rocket in the background. I suspect that is because your airframe is very thin, so there is not much material for the epoxy to wick in, therefore there isn't as much structure. I have used the Soller sleeves before, but not the type you used - just the conventional FG sleeves - and not had any issues. My 7.5" WAC Corporal is still flying after 13 flights.

As a prefect, I will say that I have concern with folks using 3D printed rail guides. I once tried the ACME Conformal rail guides in my younger days and had them snap off while loading a rocket. I learned a few things that day - surface prep is very important, and mechanical bonds are significantly better than chemical/thermal bonds. The last thing I want to do as a prefect is have to support resolution of an incident, and 3D printed guides give me pause. That being said, I'm not at the FSO table all day, so I can't catch 'em all, so a few have probably made it through.

In any case, I look forward to seeing pics of this in flight!! Keep on!
 
Neat thread, I'm enjoying this. Makes me think back to when John Buckley got his L1 on an Estes Big Bertha with a AT Single Use H124J motor. He did get his certification on that flight. It was pretty neat to watch!

You mentioned your tube not being as stiff as the rocket in the background. I suspect that is because your airframe is very thin, so there is not much material for the epoxy to wick in, therefore there isn't as much structure. I have used the Soller sleeves before, but not the type you used - just the conventional FG sleeves - and not had any issues. My 7.5" WAC Corporal is still flying after 13 flights.

As a prefect, I will say that I have concern with folks using 3D printed rail guides. I once tried the ACME Conformal rail guides in my younger days and had them snap off while loading a rocket. I learned a few things that day - surface prep is very important, and mechanical bonds are significantly better than chemical/thermal bonds. The last thing I want to do as a prefect is have to support resolution of an incident, and 3D printed guides give me pause. That being said, I'm not at the FSO table all day, so I can't catch 'em all, so a few have probably made it through.

In any case, I look forward to seeing pics of this in flight!! Keep on!

Id be surprised if the 2 or 3 threads of a 4-40 screw that actually is in contact with the airframe provide more strength than the ~1insq epoxy bond.

I bet theres a way to calculate it.. but thats beyond my skillset.

This build is taking a while longer than I'd have liked to get the electronics and recovery packing done. The maximum main chute I was able to pack was an 18" Mylar, and that simmed out to ground hit velos above 35fps. So, Ive switched from a BlueJay and separate container with eggfinder mini to a eggtimer quasar. This exchange means I gain Head End volume at the expense of adding some length (2.5"). I can now pack a 24" ripstop nylon and I gain telemetry functionality with less overall mass (1 less battery to loft).

Hoping to get her up in the Feb launch at Hearne on a F or G, and if that goes well, we will go HP at the South site.
 
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Id be surprised if the 2 or 3 threads of a 4-40 screw that actually is in contact with the airframe provide more strength than the ~1insq epoxy bond.

I bet theres a way to calculate it.. but thats beyond my skillset.
I'm more worried about the delamination of layers.
 
As a prefect, I will say that I have concern with folks using 3D printed rail guides. I once tried the ACME Conformal rail guides in my younger days and had them snap off while loading a rocket. I learned a few things that day - surface prep is very important, and mechanical bonds are significantly better than chemical/thermal bonds. The last thing I want to do as a prefect is have to support resolution of an incident, and 3D printed guides give me pause. That being said, I'm not at the FSO table all day, so I can't catch 'em all, so a few have probably made it through.

My resin-printed aero rail guides are held on with steel flat head screws going into a printed backer inside the tube that holds a steel nut. I'm really only worried about wear, which is why I made it so easy to replace them.
 
My resin-printed aero rail guides are held on with steel flat head screws going into a printed backer inside the tube that holds a steel nut. I'm really only worried about wear, which is why I made it so easy to replace them.
This is a minimum diameter project though, so no real option for through-wall guidance hardware.

So, guidance is either flyaways, or surface mounted. PETG-CF is probably at least comparable in wear resistance as Delrin.

We never had issues with large diameter rods and cardboard launch-lugs for decades.
 
Ok, thanks for the clarification.

In my experience, if you're going to have a Petg delamination, your going to see other indications of bonding failure like stringers or loops.
 
What about just printing the guides so the layers of the guide are perpendicular to the airframe and parallel to the cross-section of the airframe? Then the tension and bending loads are primarily within each layer and the loads challenging layer adhesion are greatly reduced.
 
Id be more concerned with the 3d printed airframe than small rail guides.


Much smaller moment arm/not nearly as much leverage to peel the layers apart on the rail guides
 
This is a minimum diameter project though, so no real option for through-wall guidance hardware.

So, guidance is either flyaways, or surface mounted. PETG-CF is probably at least comparable in wear resistance as Delrin.

We never had issues with large diameter rods and cardboard launch-lugs for decades.

One other choice, into the tube but no further.
My Avatar rocket is setup to take min diameter 98mm motors.

The rail buttons go into a thin conformal to the body tub bushing to clear the very small fin can bump at the end, and into the tube only to the thickness of the tube. All held in with JB weld with a fillet around the bushing as well.

Edit: Here is a good picture of another 98mm Dart I built with the Hawk Mountain fin can and tubes.

You can clearly see the bushing that I sanded to confirm to the body tube holding the rail buttons. That was to clear the bump in the fin can

The screw of the rail buttons is trimmed to not extend farther into the body tube then the thickness of the body tube.

I'm not pointing to a rail button however. I think I was joking about a scratch that the rocket got in transport to the Rock

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Several college team mentors have told me of seeing buttons (not even guides) printed with the z axis up the center of the button. :oops:
Id think that is ideal for the cylinder of the button.

It may not be maximally rigid, but it is probably the most reliable print direction overall.... plus wouldnt the screw head provide compression to resist any layer peeling?
 
Id think that is ideal for the cylinder of the button.

It may not be maximally rigid, but it is probably the most reliable print direction overall.... plus wouldnt the screw head provide compression to resist any layer peeling?
Good point. I think you're right.
 
Reworked my AV bay. Had to make a longer payload section, so did the 3D print and drilled vents, rivets, and shear pins holes.
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The eggtimer Quasar and battery will fit now.
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This may not be the final version, as I'm not satisfied the thru-wall terminals will stay connected during G-loading.
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Eggfinder Mini.
Well, I'm using a Quasar in this rocket!

We are pretty set. I may do ONE more round of ground tests, but I dont think that will be necessary.

All we need now is the 2nd Saturday in Feb and good weather. I'll plan to start her easy on an F or G 29mm motor. Just to test the guidance (I dont LOVE how my rail guides lined up) and recovery systems.

I got a LOT of feedback about breaking mach on this rocket saying I MUST have a fiberglass nosecone, including a sometime RSO... so I ordered one. It is too small. Toss it in the parts pile and maybe it will get its own rocket later.

In the meantime, Vagabond is flying with her original nose, and I'll add even more epoxy to line the nose and thicken it up if people REALLY think that will be a requirement.
 
Well, I'm using a Quasar in this rocket!

We are pretty set. I may do ONE more round of ground tests, but I dont think that will be necessary.

All we need now is the 2nd Saturday in Feb and good weather. I'll plan to start her easy on an F or G 29mm motor. Just to test the guidance (I dont LOVE how my rail guides lined up) and recovery systems.

I got a LOT of feedback about breaking mach on this rocket saying I MUST have a fiberglass nosecone, including a sometime RSO... so I ordered one. It is too small. Toss it in the parts pile and maybe it will get its own rocket later.

In the meantime, Vagabond is flying with her original nose, and I'll add even more epoxy to line the nose and thicken it up if people REALLY think that will be a requirement.
I'd not be too worried about a printed nosecone at Mach provided you could demonstrate it was designed well and was strong enough. And heating effects don't kick in till M2+.
Or print one undersized and glass it. It's pretty easy to get it smoothed/sanded to the right shape if you've got access to a lathe. Using a lathe and an angle grinder with a flapper disc will get you a shape quickly. But is messy.
Anyone who is saying you must use a fiberglass nosecone for a Mach flight is being way overly conservative. But M2 definitely.
There's a video somewhere of an M2 + flight with a printed camera shroud that melted.

Still, make sure the RSO is happy. :)
 
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I'd not be too worried about a printed nosecone at Mach provided you could demonstrate it was designed well and was strong enough. And heating effects don't kick in till M2+.
Or print one undersized and glass it. It's pretty easy to get it smoothed/sanded to the right shape if you've got access to a lathe. Using a lathe and an angle grinder with a flapper disc will get you a shape quickly. But is messy.
Anyone who is saying you must use a fiberglass nosecone for a Mach flight is being way overly conservative. But M2 definitely.
There's a video somewhere of an M2 + flight with a printed camera shroud that melted.

Still, make sure the RSO is happy. :)
This is just the estes cone... not a printed one.
 
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