L3 build - Wildman Ultimate Darkstar

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Cool. I don't want to derail the build thread, so I'll hunt that filet thread down myself. Thanks!

I'm interested as well, so if you find it first, please post a link and we can debate it over there if needed.
 
Thanks for the info. I suspected that was the reason it wasn't in the instructions, but it's nice to have confirmation. No point in adding weight if there is no strength benefit for it.

Inspecting the internals with a flashlight looking through the MMT, they look good. So I'll move on to the externals next.

For holding the payload bay to the AV-bay, has anyone used well nuts? It seems like a decent option, particularly as I have one hole about the right size drilled when testing the rivets.

I have seem the well nut used. I use pem broaching nuts personally.
 
IT IS THE ULTIMATE !

thanks for sharing, always interesting to see others techniques.

Kenny
 
For the external filets, I'm leaning towards using a 1" PVC coupler to pull the epoxy out. Any reason to use a different size?
 
For the external filets, I'm leaning towards using a 1" PVC coupler to pull the epoxy out. Any reason to use a different size?

I've seen some elaborate solutions for shaping external fillets. All I do is make them smooth with my finger and then do a lot of sanding once they're dry to get the perfect shape. I hope you post some close up pictures of the fillets when they're done because I'm interested to see how the PVC coupler method works out.
 
I've been using a 2" long piece of 1" PVC as a form tool. I put the Rocketpoxy in the joint and let it sit for about 20 minutes. Then I dip the tool in denatured alcohol and drag it along the fillet. I clean up the edges with the square end of a plastic stir stick from West Systems. These were just hit with 220 to roughen the surface.

ImageUploadedByRocketry Forum1495167522.216998.jpg
 
Nice! Here's my first go with the 1" coupler. I bought a couple others sizes and decided that this looked like the right size.

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It's because of the fillets, foam, and thrust plate... You are right. His did weigh a ton when Gus and I carried it out after the second flight.

Man, you guys haven't lived until you've carried one of Tom's rockets across the field. And I mean in pieces! :grin:
 
Man, you guys haven't lived until you've carried one of Tom's rockets across the field. And I mean in pieces! :grin:

Hence the reason he drives around with a Trailer, even if it's empty, at launches...
 
Man, you guys haven't lived until you've carried one of Tom's rockets across the field. And I mean in pieces! :grin:

Oh, BTW, I didn't use foam. I would have if I didn't get the thrust plate, but then I decided that the thrust plate was way safer and more practical. I did use 12internal fillets, though. And six external. :grin:
 
Filets completed. I need to drill the injection holes closer next time, they didn't stay filled in. I'm planning to use some Aeropoxy Light to fill them in, and maybe a little at the leading and trailing joints to the airframe.

For installing PEM nuts in fiberglass, any reason they won't pull in with the screw? Or do I need to get a clamp or long pliers to seat them? I'm thinking to use the 3mm I have, but haven't decided if I want to countersink flathead screws or just use something like a cap screw.

I plan on doing an electronics bay in the nose cone for tracking. That looks simple enough. I might have to cut a centering ring for that. Then the main av-bay.

For painting, is it worth going to an automotive type sprayer? I have a large compressor to run it. I would need to set up a spray booth of some sort. I suspect I'd have to buy a case of rattle cans. :)
 
Filets completed. I need to drill the injection holes closer next time, they didn't stay filled in. I'm planning to use some Aeropoxy Light to fill them in, and maybe a little at the leading and trailing joints to the airframe.

For installing PEM nuts in fiberglass, any reason they won't pull in with the screw? Or do I need to get a clamp or long pliers to seat them? I'm thinking to use the 3mm I have, but haven't decided if I want to countersink flathead screws or just use something like a cap screw.

I plan on doing an electronics bay in the nose cone for tracking. That looks simple enough. I might have to cut a centering ring for that. Then the main av-bay.

For painting, is it worth going to an automotive type sprayer? I have a large compressor to run it. I would need to set up a spray booth of some sort. I suspect I'd have to buy a case of rattle cans. :)

It's best to pull the PEM nuts in and glue them down with a cap screw/washer/nut combo and then spread some epoxy around the edges inside. I use a cap screw screwed into the PEM nut which I hold with an allen wrench, and slowly tighten the nut with the washer next to the airframe. As you turn the external hex nut, it'll seat the PEM nut, and the washer ensures that you don't damage the airframe. Use a standard steel screw/nut. Stainless it too soft and may end up galling the PEM nut if you're using stainless PEM nuts. As for countersinking, look into the thin head countersunk screws at McMaster. Counter sinking is an art.

As for painting, I'm biased. Ever since I set up an HVLP, spraying lacquers is super easy. MUCH easier than many would have you believe. There are many different brands of non-traditional rattle cans out there that will give you a nice finish, too.
 
I'll try that with a PEM nut. I ordered some rivets as well, but I can always use those for another project.

I've been debating with myself over the AV-bay all-thread size/count... I hate to add weight that isn't needed, but is 2@1/4" enough? I've been researching threads here, and it seems like that's the lowest people do, with 4 of them in some cases.
 
My first 6in rocket had 3/8. [1 rod in center] My second 5/16th [2 rods]

My 3rd [Ultimate Wildman] has 2 tie rods...1/4 in with 1/4 forged eyebolts. Among motors flown in it..N-5800.

I also used the rivets Tim sells to hold Av-bay into payload. I have nothing against metal screw/pemnuts etc. Just easier for me as no tools are needed.

I have built 6 Ultimates for myself & others with 1/4 inch rod/eyebolts & plastic rivets None have ever failed due to construction.

Have a great L-3 flight what ever you decide. It's all about how well your build lets you sleep at night in the end.
By the way, mine weighs 31lbs built no guts in it. [chutes-cords-electronics etc.] & that's with a cone having av-bay guts in it.


You did a real nice job on those fillets!
 
Thanks Jim! The filets are the best ones I've done so far. I was really happy with the results, other than the injection holes showing through, but that was easy enough to fix with a little filler and sanding.

I'm planning to check out the rivets from Wildman over the weekend, the package should get here Saturday according to USPS. Great service from Wildman shipping the order out quickly. I'm leaning toward using them if they feel strong enough, which they likely are. They have to be stronger than the shear pins in the nose cone, which isn't really that strong. I have 3 #2 pins now, but I think I'm going to go up to #4. I just happened to have the #2s out on the bench so I used them to do the initial alignment.

Part of my order is a centering ring to build a nose cone av-bay. I might not populate it for the L3 flight, but I want it there just in case. I could have cut one, but I didn't have any 1/2" ply on hand and for $7 I figured it was worth just tossing one in the order.

Thanks for the info on weights and tie rods. I think I'm going to do 2@1/4" with u-bolts for attaching the recovery gear.

Getting close to being ready, I might even have time to paint it. :) Planned flight is August 5 at Hellfire.


TODO:

Complete nose cone av-bay and recovery attachment
Complete main av-bay and wiring
Install PEM nuts or rivets for av-bay to payload attachment
Install rail buttons
Install 98/75 motor adapter on the case
Complete cert documents and make a pre-flight checklist

Purchase 98mm Aeropack retainer and install on the thrust plate
Purchase shock cords from onebadhawk

Lots and lots of ground testing
 
Coat your screws with Vaseline, go ahead and tighten them into the PEM nuts, and epoxy over them. Once the epoxy is dry, a brisk turn with the screwdriver will free them from the epoxy and get them right out.

But instead of PEM nuts, I would go with these: https://www.mcmaster.com/#weld-nuts/=17w8t5h
 
Had a weird thought and made a 3D printed drill template for the AV-bay caps....

Just for the u-bolts and tie rods.

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What's weird about that?


Perhaps not "weird" so much as "I don't think I've seen people do it before". I was originally playing with the CAD program to see how things would fit on the plates, but suddenly realized I could make a template and avoid laying them out by hand. I put the charge holders and terminal blocks on the template just to check fit and it's downright spacious compared to what I'm used to. :)

It was a somewhat tight fit on my printer, but managed to get it to fit by using the ledge that fits inside the bay as the ID. It snaps over that and fits near perfectly. I must be getting a little better at estimating the "shrinkage" of holes that get printed.

Oh, just noticed your L2 bird is a Vertical Assault. I like that rocket. Managed to break mine when the apogee charge didn't happen. Main deployed, so most of the lower airframe is good and saved the motor case. Keep meaning to get some new tubing and fix it up. :)
 
My VA died when the altimeter decided that it had reached apogee while still under thrust at about 550 mph. Learned a big lesson about sizing vent holes that day. :wink:

I don't have a 3D printer, but I usually make my template on paper, then tape the paper to the thing I have to drill. Works better than it sounds, but probably nowhere near as well as your template.
 
Perhaps not "weird" so much as "I don't think I've seen people do it before". I was originally playing with the CAD program to see how things would fit on the plates, but suddenly realized I could make a template and avoid laying them out by hand. I put the charge holders and terminal blocks on the template just to check fit and it's downright spacious compared to what I'm used to. :)

It was a somewhat tight fit on my printer, but managed to get it to fit by using the ledge that fits inside the bay as the ID. It snaps over that and fits near perfectly. I must be getting a little better at estimating the "shrinkage" of holes that get printed.

Oh, just noticed your L2 bird is a Vertical Assault. I like that rocket. Managed to break mine when the apogee charge didn't happen. Main deployed, so most of the lower airframe is good and saved the motor case. Keep meaning to get some new tubing and fix it up. :)

I've done this a couple of times...it's really really great to plot it all out and drill accurately with very minimal hands on time. That said, you could save a lot of material by just doing the minimal amount.

I typically drill the center hole in order to turn the bulkhead round on my lathe. Then I use that as my location hole by using a dowel pin with my printed guide. Drill the first hole and then pop in another dowel pin and then drill the other holes.
 
You're absolutely right that I used way more material than I needed to. I also have a pile of pellets I make filament out of, so it's not as expensive to print it as you might think. :) However, it did take about 5 hours to print, so there is that. I like your idea, I might have to try something similar. It would be easy to cut a slot out of the middle of the circle in the CAD.

I'm beginning to think a lathe is like a hammer, when you have one, everything looks like a lathe project. :D
 
You're absolutely right that I used way more material than I needed to. I also have a pile of pellets I make filament out of, so it's not as expensive to print it as you might think. :) However, it did take about 5 hours to print, so there is that. I like your idea, I might have to try something similar. It would be easy to cut a slot out of the middle of the circle in the CAD.

I'm beginning to think a lathe is like a hammer, when you have one, everything looks like a lathe project. :D

In rocketry...yes, yes it is.
 
I haven't stopped working on this. The bulkheads are done, as is the nose cone recovery attachment. I'll add pics later. I also ordered the recovery harness and hardware from onebadhawk.

I started researching the altimeter vent size. I have some conflicting information. I found a spreadsheet here on TRF that indicated about 5/16" was about right.

https://www.vernk.com/AltimeterPortSizing.htm

That doesn't go quite high enough, but it seems to match up. As I would want a little bigger than 1/4".

The steps from eggtimer in this thread though..

https://www.rocketryforum.com/showthread.php?52044-Static-port-calculator

Seem to indicate 2x the size.

3 holes, 6" diameter, 16" long.

I've been lax before with this part of design and usually just went with the same size as kits of the same diameter. I want to be more precise with recovery going forward.
 
Do pics sweeten the deal? :)

Inside the nose cone, centering ring epoxyed in after sanding and cleaning with alcohol to ensure a good bond to the fiberglass. The fifth screw is mostly to help out with alignment. The hole is for a 75mm tube, so I can build a forward AV-bay.

AV-bay bulkheads with 3/4" copper pipe charge holders and screw terminals.
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L3, achieved. Apogee at 6477 feet according to the Quantum, everything went perfect. Thanks for the advice both in the thread and in general on the forum from everyone.


Here are a few build pics showing ground testing and the AV bay design.


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Brian Schaaf‎ got this photo of the launch itself.

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And Jack Anderson made a nice video.

https://www.facebook.com/jack.anderson.583/videos/10210540872781332/


HellFire was being covered by a reporter for a local paper that decided to include some info about my rocket as well..

https://www.sltrib.com/opinion/kirb...-shooting-off-rockets-even-when-they-go-awry/


StickerShock23 did an amazing job on the wrap. I did a somewhat decent job applying it... :)
 
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