Yet another Wildman Jr Build for Level 2

[AcadiaRockets]

@pathtouch I have a pretty full slate already after last months club launch was scrubbed. This month I have the Eagle Claw, SBR Bullet, and Sasha maiden flights. And Grayson has a few LPR to go up.
The Wildman Jr. will get bumped to the November meeting. I do want to do my written this month though. Thanks.

 

[AcadiaRockets]

EXPANDING FOAM PART ONE
This is still the trickiest part to me. I will outline my process here though.
So I wanted to use this epoxy again as the space in the Wildman jr was small and I wanted to get better at using the foam.
First step since the foam is reactive to heat, I put everything in the fridge all day. The two part foam, the syringe, the tubing, my stir sticks, and the little cups for measuring.
Everything being cold buys you valuable seconds for mixing and injecting.

Make sure everything is laid out and you have your steps down. A practice run in a cup wasting precious epoxy is wasted epoxy WELL SPENT.


Those dental irrigators hold about 20g of epoxy total. 9g of each part is about right. More than that will make it shoot out the top before you get the syringe together when it starts to kick. If you need more than than, do a second batch.




View attachment pour epoxy.mp4
I cut the tip off the syringe and fitted a piece of tube to got to the bottom of the space.
If you try to just pour it in the space, it will kick on the way down, preventing a full pour and you will end up with an unfilled void at the bottom of your space.


Part B is more viscous than part A. Why does this matter? If I am pouring one or the other into a syringe and it starts kicking on contact, I want to put the slow moving part B in the syringe first. It can sit there and when I put the less viscous part A on top of it, the part A comes out of the little cup faster, and I can start stirring as soon as the little cup is empty.
I did say this all happens REALLY fast.


Have your tube in the rocket at the bottom of the space ready to go. Have your kebob mixing stick ready to go. The kebob stick needs to be able to go into the neck of the syringe to mix the little bit in there.

 

[AcadiaRockets]

EXPANDING FOAM PART TWO
Alright holding your finger under the tip, you pour them both in the syringe and have literally only seconds to stir using a stabbing motion making sure to get that little bit in the neck.


Almost right away it will start turning opaque and creamy colored. YOU ARE ALMOST OUT OF TIME! Don't put the plunger in yet. But pulling your finger away, get that syringe on the tube and then get that plunger in fast! Its expanding and can go out the wrong direction.
View attachment inject.mp4


Inject it into the bottom of your project. Pull the syringe off the tube, pull some air, back on tube, blow rest of epoxy out of tube.

It will still be liquid enough a the bottom of your project, take these seconds to use your kebob stick to stab and mix the epoxy some more at the bottom.

View attachment stab.mp4

Its going to be expanding at this point so take a breath and watch the cool epoxy do its thing

 

[AcadiaRockets]

I used a screw driver to scrape the foam back till the base of the fins could be seen and did that level all around. I then coated the inside with BSI 30 and pushed the after centering ring down onto the exposed fins bottoms and foam. Thats a lot of contact all around in there and should be solid for my first Mach plus rocket.


I used some carbon paper and a fondant tool to mark the fillets. I masked off the whole thing and made fillets with Rocket Poxy. I really like working with the rocket Poxy - it is the right thickness for this application, I can do all the fillets at one, it won't sag, and smells nice.

 

[AcadiaRockets]

Holes! So many holes! - Part one
The first holes drilled earlier were for the rail buttons. I like the rail buttons with the inserts so those holes are larger than a #6 screw.
But the holes today were many and varied. And while I knew what size I wanted them all, I spent a lot of time organizing them around the rocket so that they would be hidden (ish) from the front /pretty side.
I started with the holes that stressed me out the most. The holes to accommodate the pull pin in the e-bay. they are not 180 degrees from each other and since they are not immediately across they are not "straight" in either. There is probably some math I could figure this out with but what I ended up doing was shaving a toothpick down enough to slide in the switch and then trimming it just enough so the sled slides into the e-bay dragging both sides of the toothpick down. When I closed up the e-bay I can see the ends of the off center toothpick pressed up against the side of the red fiberglass. Did I mention how much I love Wildman's red airframes?

So Using a pencil I marked where the pick touches, and then put a tiny piece of tape over the spot I dremeled the hole at an angle with the help of the tape so the bit does not skate off. Repeat on the other side. Presto - remove the pick and the switch pins goes all the way through at the right spots. Since one half of the vent band is long that the other now that will be the "front" facing side. And since I want three vent holes, I split the difference on the short side and drilled a third hole for a total of three holes for the RRC3.

 

[AcadiaRockets]

Holes! So many holes! - part 2
Shear pins. This is the first rocket I have ever used shear pins in. I decided on just one 2-56 shear pins for each the booster and for the payload.


I drilled and tapped for the booster in line with a fin not in the way of the rail, halfway between the bulkhead and switch band.


On the payload in in line with the aft shear pin and half way between the nose cone shoulder and nosecone bulkhead.


In an earlier post I built my nosecone insert for the GPS. I need to secure that to the nosecone shoulder. I drilled and taped that for two screws opposite sides then I used a larger drill bit to remove by hand enough material to accommodate the screw head so the nosecone slides up and down without catching on the screws.

All these hole and still no vent holes. I decided on 1/8 holes would be enough via different calculators. Tell me if I am off. The Payload vent hole I put a half caliber below the nose cone. The Booster vent hole I put half way between the fin can and aft e-bay bulkhead since pyro charges will be coming from both directions in there.



Could I be ready to launch this single deploy this weekend? hmmmmmmmmm

 

[ksaves2]

Ahhhh, You're super smart using a GPS tracker. A J350 is going to punch it pretty high. I can't remember but I think my WM Jr. was like 5 to 7k in altitude and I needed the APRS GPS tracker to find it. Tracker on top in NC and Raven 2 in the ebay (if I remember correctly). It's a beech to get the nosecone modified but worth it. I gotta go downstairs and dig out my WM Jr.'s Got a couple and I think I did a N.C. tracker on one and did a long neck extension on another and put the tracker in the ebay with the antenna "stented" into the upper ebay. I still got both of them. Flew with the J's and several research H's, I's and J's. Still got them and flyable today. Thank heavens for the APRS/GPS tracker. APRS is the Ham radio protocol though I've used the non-licensed 900Mhz equipment. The Ham stuff has a better ground footprint but for the sport flier, 900Mhz will be fine.
I was carrying a heavy laptop (for the time) to the recovery site as I had a mapping program on it but never lost the WM Jrs. or any rocket I've had GPS tracked. The last known position on the freak'in map really helped me as I'm a visual map sort of guy.
If one is going to do a really crazy launch that is expected to land many miles away from the launch pad, get a Ham license and use 70cm and 2 meter bands for APRS tracking if room permits. Will increase one's chances of recovery. I've used Eggfinder stuff and it's great with my sport fliers that land within 3 miles. I've hacked some receiver software and can watch my rocket on a photomap. No big deal as I know exactly where the ground print is of the rocket and can search accordingly. Never fails.
One caution. High powered Rf can interfere with deployment electronics so I HIGHLY recommend one mocks up a rocket configuration with live contained ematches on their deployment altimeter(s) No 4F powder in the canisters. Start the tracker, let it get a position then turn on and arm the altimeter(s) for a simulation. If the ematches don't "pop" after 20 or 30 minutes with this test, one should be good to go fly.
How do I know this? It's embarrassing as hell to have a rocket start blowing charges on the launchpad!!! Been there, done that!
Learn from my mistake! Took me a couple of times to realize the Rf was interfering with the deployment electronics.
If one buys a combination GPS tracker/deployment electronic device, don't worry about it as the maker has already tested for compatibility. I have a couple of units, one on the Ham bands and one on the unlicensed 900Mhz band. They work fine right out of the box. Kurt



Kurt

 

[Hobie1dog]

Ahhhh, You're super smart using a GPS tracker.
If one buys a combination GPS tracker/deployment electronic device, don't worry about it as the maker has already tested for compatibility. I have a couple of units, one on the Ham bands and one on the unlicensed 900Mhz band. They work fine right out of the box. Kurt

Which exact one are you talking about?

 

[ksaves2]

Which exact one are you talking about?

The Altus Metrum "TeleMega" and the Eggtimer "Eggtimer TRS". I just did a website review and the TRS is out of production. I bet it's due to a critical part being no longer available. Too bad. A 900Mhz tracker/deployment altimeter was a nice tool for folks who weren't licensed Ham radio operators. Yeah, it had a big footprint but "big" rockets usually have a lot of space for "big" electronics if one gets creative. The plain EggFinder is still available though.
EggTimer stuff can be had on the Ham bands too but one has to build'em. No big deal for me with the soldering station I have.
That leaves the Telemega but if I recall correctly, I had to wait awhile to get mine.
Flew my Beeline GPS trackers quite a bit and dorked one in the early days with a lawn dart. That $$$$$$ hurt too. Lawn darted an Eggfinder and didn't $$$$$$ "hurt" so bad.
Rocketry is like fishing. If one wants to catch fish, they're going to lose fishing lures on snags and such. If one flies rockets, they're gonna lose some and lawn dart the others! (Besides having some nominal recoveries) Kurt

 

[b.wieting]

Cris just announced a "new and much more modern" replacement for the TRS due out late this month.
BTW, even with my somewhat unsteady hands, I found building an Eggfinder set pretty straightforward, made much easier by great documentation and support.

 

[AcadiaRockets]

Would you put wadding in a drogueless booster? why?

 

[rocketgeek101]

Would you put wadding in a drogueless booster? why?

Only if there is something fixed to the shock cord that I wanted to protect like a noisemaker.

BTW I see from your sig you fly in Cherryfield. You probably would have met a flyer in my club who also regularly goes across the border to fly there by the name of Mark Roberts. I hope to make it down there one day myself. I currently fly HPR in Gagetown which is located in south central NB.

 

[AcadiaRockets]

We absolutely know Mark. He has given my son some rockets to build that we are flying next week. I have been to Gagetown back in the day, not for launching but I've been there. Love the drone video from your last launch.

 

[waltr]

Would you put wadding in a drogueless booster? why?

Any rocket about 1.6inch and larger I use a Nomex blanket instead of wading.
And yes, I do use Nomex so 'wadding' attached to lower end of shock cord just above the end of the BT.
Then lay the Nomex across the BT and put cords onto Nomex and push into the tube forming a plug. This protects the cord and anything above from motor ejection charge.