RW 6-inch Stinger build

[Tobor]

First I wish to thank @GRIFFIN for the choice deal on this kit. This RW Stinger will be my first 6 inch build, and will be a good learning experience as I work towards my Level 3 Cert build.
I will be trying some new (for me) ideas and techniques like a donut AV bay, stenciled lettering and a few 3D printed bits to spice things up. I may also add onboard video to this build, but I still have a few things to work out first.

Btw, unlike most of my other builds, the plan is to have this ready for this falls MWP

OpenRocket estimates the final weight without motor to be approx 14lbs.

Color scheme will be a simple affair. And since the airframe is already blue, it will just get a clear coat, sorta...

Anyhoot, here are some pics of what I have in mind.









Time to get ready for work.

 

[UPscaler]

Very nice! My dad used one for his L3 cert! He just recessed the lower av bay lid into the coupler, but obviously, that limits his motor length to the 5120 case.

Should be cool!

Braden

 

[jmasterj]

Looking forward to seeing the donut av-bay work!

3D print there is a short tailcone? Be careful, that will reduce your base drag (and that weightless drag cone might not be valid anymore).

 

[Hardline]

My 6 inch Stinger came in at 17.5 lbs with it's Donut Avbay.

on one side of the Avbay is a sled with a RRC3 and a stratologger and on the other side I have a sled with an EggFinder and a Featherweight GPS.

I added a Mobius camera shroud from Additive Aerospace.

I throw a CSI tracker in the fincan in case of separation.

It flies very happily on CIT L1115 and CTI M1101's to around 10,000'

One of my favorite rockets. Enjoy your build.

 

[crossfire]

Just wondering how long of a motor would fit with out donut avbay?

 

[rfjustin]

Just wondering how long of a motor would fit with out donut avbay?

Likely a (3) grain 75.

 

[Bat-mite]

One of the MDRA board members got his L3 with a Stinger, IIRC. Have fun!

 

[crossfire]

I had a bad experience with a donut avbay.

 

[sharkbait]

My 6 inch Stinger came in at 17.5 lbs with it's Donut Avbay.

on one side of the Avbay is a sled with a RRC3 and a stratologger and on the other side I have a sled with an EggFinder and a Featherweight GPS.

I added a Mobius camera shroud from Additive Aerospace.

I throw a CSI tracker in the fincan in case of separation.

It flies very happily on CIT L1115 and CTI M1101's to around 10,000'

One of my favorite rockets. Enjoy your build.

You guys are making my Stinger feel embarrassed, she’s 19lbs

 

[Tobor]

You guys are making my Stinger feel embarrassed, she’s 19lbs

 

[jim_kc]

Looking forward to the build, thanks for sharing!

 

[Tobor]

Very nice! My dad used one for his L3 cert! He just recessed the lower av bay lid into the coupler, but obviously, that limits his motor length to the 5120 case.

Should be cool!

Braden

Thx. Yeah, I recently watched one of your vids where you and your dad were talking about that rocket. And btw, I am a fan of your YouTube channel. Sometimes I do forget to log in b4 watching but eventually I do go back and "Like" what I've watched.

Keep up the great work.

 

[Donnager]

Just wondering how long of a motor would fit with out donut avbay?

Mine might have been a little heavier. I had to add a 2' extension to fly a K435, to make it work.

 

[Tobor]

So the build has started.
I worked out a plan for adding 13 oz. of #7.5 lead shot to the pointy end of the nosecone.

My initial setup used 125mm length of threaded rod (TR) and a 2.6" FG bulkplate to anchor the NC tip. As the lead shot took up less volume then anticipated, I replaced the 2.6" BP with a 54mm piece. Then I remeasured the length for the TR and figured it's final length at 98mm.

TR attached to a second piece of TR using a threaded coupler.


I prepped the NC tip by adding petroleum jelly to it's threaded hole (To keep epoxy from seeping in), cleaned it's base with denatured alcohol and then applied a layer of yellow "Frog Tape". The tape will prevent the base from bonding with the epoxy.


Added a bulkplate and nut to the back end of the long piece of threaded rod. Feed the contraption through the bottom of the NC and screwed on the NC tip onto the short piece of TR. After standing the NC up, I used masking tap to affix the tip to the NC. Next, while holding onto the TR, I turned the NC upside down and inserted it into the airframe. Then I placed pieces of aluminum angle across the base of the NC and carefully centered the threaded rod to the NC before snugging down the bulkplate with the hex nut.

Next I mixed up 40 ML of Aeropoxy and poured it into the NC while aiming for the base of the NC tip. I was moderately successful there... Then I slowly added the lead shot so all the shot would get coated with the epoxy. I ended up needing to add another 20 ML of Aeropoxy to complete the job.

That's it for tonight...

 

[Tobor]

Today I received tracking info for the Wildman order I placed Sunday evening!
The order includes a custom cut G12 CR to fit...

This guy, a GLR 75mm SlimeLine Retainer.


When I picked up this kit from Griffin, he had offered to sell me an Aero Pack retainer, but at that time money was really, REALLY tight. Then in June I discovered I was short on airfoiled 1010 rail buttons, so I padded the GLR order (Using BAR HPR logic) with the retainer to make it worth the shipping charge. Additional padding included a pair of airfoiled 1515 buttons for my future L3 project. (More BAR HPR logic).

Also, yesterday I visited my local HomeDepot looking for some 1/8" and 1/4" plywood. All they had was over priced, badly warped, inferior grade "Metric Equivalent" plywood....

Amazon to the rescue! Found some Midwest Products "Craft Grade" "Metric Equivalent", which I know is much better then anything HD had to offer. I also added some Blue resin dye to the Amazon purchase. The dye has been sitting in my cart since last springs MMWP.

Last but not least for this post I give you 3D printed rail button anchors.



Yes, these are modeled on Lab Rats products, although mine use the standard hardware store Tee-Nuts made for anchoring in wood. And before you go off the deep end, I have purchased some from Chris in the past, and will continue to patronage his site for other products he sells online. Also, before anyone asks, I won't post or share the STLs, unless Chris gives his blessing.

Till next time.

Edit: Other pics I forgot to post last week.



Added more epoxy to the base of the NC weights



And finished that off with FG bulkplate and 1/4-20 Eye Nut



Take 2, cut...

 

[Tobor]

My order from Tim & Jackie arrived today! And my Amazon order is waiting for me at the nearest Hub Locker.

The custom CR required about 15 seconds of sanding the I.D. to achieve a nice snug fit over the motor retainer. I also worked on the fins slots. Each slot needed to be extended approx. 3mm on the back end. Then I sanded down both of the MMT CR O.D.s a tad for a perfect fit in the airframe.

Did a dry fit of the business end and checked the clearance for the tailcone.



For many moons now I've had the idea of 3D printing a form for external fillets. Maybe in the future I'll take a shot at it. The reason I mention the form is that while I was working on the OR file for the Stinger, the thought occurred that I could 3D print a form for Internal fillets. The idea being to glue the forms in place using 5 minute epoxy. Then, after a couple of hours, I would stand the airframe bottom end up and pour all my internal fillets in one go.




Do to the MK3S's vertical print height limit of 250mm, I had to split the left and right forms in half, for a total of 12 pieces + the 6 couplers that will be used to glue each pair of forms together. I also decided to divide the print job into 3 batchs. 2 for the forms and 1 for the couplers.

I toyed with the possibility of coating the forms so I could remove them after the fillets had completely cured. But, I think the effort is not worth the time of trying to apply several coats of release agent in just the right spots while keeping other areas clear for the 5 minute epoxy. So, these forms will have a permanent home aboard the Stinger.

 

[Hobie1dog]

builds like this one makes me realize I'm in my infancy of rocketry. Love all the pictures, thanks.

 

[Tobor]

I learned something new last weekend "How to ruin a 3D printer's brass nozzle"

Having the day of last Friday, I did some maintenance on my MK3S. Dusted off the frame, wiped and greased the guide rails, and cleaned the nozzle and heater block with my brand new brass wire brush. Afterwards, I prepped and started a print job for the Stinger's Fillet Mold Couplers but my filament refused to stick to the build plate. Even Magigoo didn't help the issue.

Welp, it turns out the wire brush had filed down the tip of the nozzle and changed it's geometry enough that the MK3S's Live Z Adjustment could not compensate. Frustrated, I did some chores around the house. On Saturday, I replaced the nozzle, recalibrated the Z height and got back to printing stuff.

I tested the new nozzle by printing the couplers for the fillet molds.


And, last night I printed a Drill & Router Guide for the AV bay's centering rings and forward FG bulkplate

Crop circles? Alien influence....





I will use the bulkplate as a cutting guide for the plywood CRs O.D. using the Freud 1/2" Top Bearing trim bit (Link) I ordered last night on Amazon.

 

[Tobor]

Yesterday I tried my hand at shaping CR's with a template and router. It worked but.... 3 times the cutter grabbed the plywood. Once cutting the OD and twice cutting the ID. Totally my fault. The CR's survived and the template is destined for the scrap box. The experience has taught me the importance of getting a proper routing table. That will be a future DIY project.

Anyhoot, here are the pics

Before



After


The centering rings are made from 2 sheets of Midwest Products "Craft Grade" plywood (304mm x 152mm x 3mm) glued together with Titebond III.
The markings on the template are CW = Charge Well and TR = Threaded Rod.

 

[Tobor]

I woke up 3:30 am this morning....... yuck.

Since I could not get back to sleeping the deep sleep I decided to place an order with LOC (Still more BAR logic). Included in the order is the 75mm MMT I need for the donut bay, some 3mm sheer pins and a roll of the carbon fiber cloth that LOC offers. I also ordered some BSI 15 minute epoxy. One can never have too much epoxy...

 

[Tobor]

First batch of fillet mold forms are printing as I type this. ETA 6:30am. Keeping fingers and toes crossed...

Edit:

 

[Tobor]

No printing mishaps yesterday.



I will print the 2nd batch in the next day or two. In other printing news, last night I printed a support ring for my drill template that fits the 6" airframe CR. That CR will serve as the anchor plate for the AV Bay.

In still other news, yesterday my LOC order arrived! So I got busy sanding the ID of the donut bay CRs for a nice snug fit on the 75mm MMT.

 

[Tobor]

Update:
Saturday morning I used Forstner bits on the donut bays fwd CR to drill 1/4" holes for the two allthread rods and 7/8" holes for the charge well holders. In the afternoon I started printing the 2nd batch of fillet mold forms. The print finished at 3:27 this morning.

About an hour ago I started printing the four pieces that make up the charge well holders. The holders will be home to 1/2" copper pipes with associated end caps.

 

[Tobor]

Today I decided to take the plunge and go the West System route for the internal fillets. But man... stepping into the pond will set me back $130+ to $150+ including Tax for the "A" size loadout w/pump set + the small or medium size Colloidal Silica Filler.

There is a West Marine store a few miles from my place so this will be a local purchase. I will head over there in the next couple of days. Hope my better half doesn't inspect the work table anytime soon....

 

[Tobor]

Ta-Da!!!

 

[Hobie1dog]

thanks for all the pics, you can do this.

 

[Tobor]

Began assembling AV bay this afternoon, mostly with 5 minute epoxy.



So far it's fairly square'ish... (Truly flat wood of any kind is hard to come by these days.)

For now the other end will remain open until I get the charge wells assembled and mounts for the EggFinder and Proton printed and installed. That will make fishing any wiring much easier.

 

[jd2cylman]

L3 at MWP XX?

 

[Tobor]

L3 at MWP XX?

No Sorry.

I am really not ready for that experience. But the Stinger is part of my roadmap to getting my L3.

This morning I made time to work on the charge wells.



Used my MAP gas torch and Silver solder to make quick work of soldering the 1/2" copper end caps onto 1/2" copper pipe. Piece on the far left is a completed (dry fit) charge well. I will be using RocketPoxy for the final assembling.

 

[jd2cylman]

No Sorry.

I am really not ready for that experience. But the Stinger is part of my roadmap to getting my L3.

This morning I made time to work on the charge wells.

View attachment 534260

Used my MAP gas torch and Silver solder to make quick work of soldering the 1/2" copper end caps onto 1/2" copper pipe. Piece on the far left is a completed (dry fit) charge well. I will be using RocketPoxy for the final assembling.

I just drill a hole through the bottom of the copper cap and bolt the charge wells to the bulkhead.