By Grabthar's Hammer! A LOC Skinwalker thread!

[krislhull]

It has been 5 years since my last large build, and I have been wanting to build something larger for some time. Well, an email on my local club's mailing list finally gave me a reason to do build a bigger! After reading through the email from the fellow club member, I realized that I would love to help, and would need a bird with a 98mm mount, and that could stay under the waiver of our regional launch site. Since I do not own any thing with a 98mm mount, I finally had an excuse for a larger build! It would have to be something that I could build in time for a Labor Day weekend launch, and I wanted a simple, yet strong build...

So, enter Grabthar's Hammer! AKA, a basically stock LOC Skinwalker...

After I placed the order on LOC's website a couple of months ago, I obtained the Rocksim file, and I did something I have never done before this early in the process: I started to design a livery and theme for the rocket. Being a fan of the amazing cinematic masterpiece that is Galaxy Quest (And one of the best Star Trek movies), I decided Grabthar's Hammer would be a perfect name for SWR-61, my Skinwalker number. I then came up with a paint scheme based on the character Dr Lazarus's (played by the late, great Alan Rickman) uniform from the movie.






The massive box from Wisconsin arrived on my front porch just over a month ago, and the first order of business was to order a motor retainer and a main chute.
Both were obtained from Wildman: A 98mm Aeropack retainer, and a Skyangle Cert 3XL parachute for the main. I plan on using the Skyangle Cert3 drogue from my L3 build on this to help keep costs somewhat down. Avionics will be a Perfectflite StratologgerCF and a Eggtimer Quantum for altimeters, and a MissileWorks RTX for GPS tracking. The build will be mostly stock, with no fiberglass on the tubes. the entire airframe will be reinforced with couplers, and airframe joints will all have LOC stiffy couplers as well. I will be using West System 105/205 epoxy for the build, and it will be my first time using West Systems, as all of my previous builds have been either US Composites or Rocketpoxy. I may change out the nosecone, but will most likely keep it stock. The proposed motor for this rocket's initial reason for being built will be a large L to mid M, not sure which yet.

Now, on to the start of the build!

I finally was able to get started this weekend, and the first thing to be done was to mark a line for future mounting of the rail buttons onto the booster section.



I then mocked up the fin can to mark the location of the centering rings before starting to epoxy them to the motor mount.



Then it was time to start flowing the epoxy! The lower two rings are in place (although in the photo below, the second upper ring is not epoxied on yet), and the fins will start going on tomorrow after work.

 

[bad_idea]

What a savings.

Being a fan of the amazing cinematic masterpiece that is Galaxy Quest (And one of the best Star Trek movies

Ahem.

I think you meant to say:

Being a fan of the amazing cinematic masterpiece that is Galaxy Quest (And one of the best Star Trek movie

Love the theme of your build, even as I curse my luck that you trumped me on the name, which I'd planned to use myself on a future build. Looking forward to seeing this one come together!

 

[krislhull]

Love the theme of your build, even as I curse my luck that you trumped me on the name, which I'd planned to use myself on a future build.

Who says only one can use a name for a rocket???????

 

[dhbarr]

Clearly you need to build Suns of Warvan.. Y'know, for vengeance.

 

[krislhull]

Clearly you need to build Suns of Warvan.. Y'know, for vengeance.

Oh, its in the planning phase......... Next year........

 

[Ronz Rocketz]

You broke the ship... you broke the bloody ship!

Miners! Not minors...

 

[KenECoyote]

What is this rock(et)'s motivation?

 

[krislhull]

Over the past few days, I have installed the fins onto the motor mount assembly. This is the first time I have built up a fin can out side of the airframe like this, and it is certainly easier to do the internal fillets! Once all of the fins were on, I started applying said fillets to the fin/motor mount joints using West Systems epoxy mixed with fumed silica. Tabs for securing the lower two rail buttons were also installed onto the centering rings at this time.

 

[lr64]

What a savings.

Ahem.

I think you meant to say:



Love the theme of your build, even as I curse my luck that you trumped me on the name, which I'd planned to use myself on a future build. Looking forward to seeing this one come together!

I'm sure Grabthar had many other posessions.
Grabthar's Sword
Grabthar's Machete
Grabthar's Pocketknife
Grabthar's Circular Saw
Grabthar's Ferrari

 

[KenECoyote]

Grabthar in action:

 

[boatgeek]

I'm sure Grabthar had many other posessions.
Grabthar's Sword
Grabthar's Machete
Grabthar's Pocketknife
Grabthar's Circular Saw
Grabthar's Ferrari

I feel like Grabthar was more of a concussion weapon kinda guy. Hammer, mace, morning star, flail…

 

[kjhambrick]

I'm sure Grabthar had many other posessions.
Grabthar's Sword
Grabthar's Machete
Grabthar's Pocketknife
Grabthar's Circular Saw
Grabthar's Ferrari

Somehow, it just wouldn't be the same

 

[dr wogz]

I'm sure Grabthar had many other posessions.
Grabthar's Sword
Grabthar's Machete
Grabthar's Pocketknife
Grabthar's Circular Saw
Grabthar's Ferrari

if you have all 5, do you get a +6 on your dice rolls?!

 

[Rschub]

Only the Vorpal Sword has +6

 

[lr64]

I feel like Grabthar was more of a concussion weapon kinda guy. Hammer, mace, morning star, flail…

Anvil? If Grabthar is in the Warner Brothers world, maybe a safe? Pile driver? Lineman?

 

[-Slick-Ice]

I love this project - Subscribed.

 

[krislhull]

Got a little more progress made on Grabthar's Hammer over the past two days. After getting all of the internal fin fillets completed on the motor mount, I slid the whole assembly into the body tube to check alignment and to drill the holes for the lower rail buttons.



This thig is a beast! The method I am using for mounting the rail buttons is one that I have used on most of my high power builds with 4" and larger airframes. I used it to great success on my L3 project as well. However, for some reason, this time around, when I went to drill the holes, the tabs broke off a few times. It was a pain to pull the whole assembly out, resecure them with 5 min epoxy, and then repeat the whole thing, and in the end, I ended up using some scrap 1/4" balsa strips to create a support under each tab.



Once the holes were located for the buttons, threaded inserts were installed into the tabs epoxied on the centering ringer earlier. It was now time to permanently install the mount to the airframe.... West Systems was painted inside the airframe where the upper centering ring on the fins will sit, and then the whole mount was slid into place. I then pealed back each section of airframe between the fins and painted more epoxy onto the centering rings before securely clamping everything down to cure. The tabs I cut out to make the fin slots full length to the end of the tube were then epoxied back into place behind each fin for cosmetic reasons.



One tool that I have been making extensive use of on this build so far is my new Milwaukee cordless rotary tool. I have been using a 23 year old Dremel, and it still works great, but this cordless one is awesome to have. If you are in the market for a new Dremel type tool, I would highly recommend it!

 

[krislhull]

The project received a very nice care package from @Onebadhawk today.....



Teddy came through yet again with his awesome customer service and amazingly fast turnaround! Plus, the purple can coozie will match the final product perfectly!

Now, to get over this strep throat so I can get back to working on it!

 

[krislhull]

Finally found the motivation to get back to working on this build after being sick with strep and then Covid the past few weeks.

After work today, I was able to get the fillets on all 4 fins completed. I used West System Six10 for the first time, and I think I am sold on using it for fillets from here on out! This stuff works great in this role!





I was able to get all 8 fillets done in about 30 minutes, and there is no sagging or dripping.... very easy to work with!

 

[bad_idea]

Finally found the motivation to get back to working on this build after being sick with strep and then Covid the past few weeks.

Yikes! Glad you're doing better.

 

[Ronz Rocketz]

Finally found the motivation to get back to working on this build after being sick with strep and then Covid the past few weeks.

After work today, I was able to get the fillets on all 4 fins completed. I used West System Six10 for the first time, and I think I am sold on using it for fillets from here on out! This stuff works great in this role!

View attachment 650633

View attachment 650634

I was able to get all 8 fillets done in about 30 minutes, and there is no sagging or dripping.... very easy to work with!

For a moment, I thought you used hot glue.

 

[Tim51]

Finally found the motivation to get back to working on this build after being sick with strep and then Covid the past few weeks.

After work today, I was able to get the fillets on all 4 fins completed. I used West System Six10 for the first time, and I think I am sold on using it for fillets from here on out! This stuff works great in this role!

View attachment 650633

View attachment 650634

I was able to get all 8 fillets done in about 30 minutes, and there is no sagging or dripping.... very easy to work with!

I too am a Six10 fan for filets, although I find the special mixer nozzle means it takes some considerable effort to push it through if using a manual caulk gun.

 

[boatgeek]

I too am a Six10 fan for filets, although I find the special mixer nozzle means it takes some considerable effort to push it through if using a manual caulk gun.

I found on the equivalent System 3 products that you don’t need the mixer tip if you’re not doing internal fillets or another job where the tip is helpful. Just uncap the tubes, use a caulk gun to squirt out however much you need on to parchment paper or whatever, and use a pair of Popsicle sticks to strike off each part flush with top of the tube.

 

[Tim51]

I found on the equivalent System 3 products that you don’t need the mixer tip if you’re not doing internal fillets or another job where the tip is helpful. Just uncap the tubes, use a caulk gun to squirt out however much you need on to parchment paper or whatever, and use a pair of Popsicle sticks to strike off each part flush with top of the tube.

Thanks - good idea.

 

[krislhull]

This morning, while I had our Saturday morning cinnamon rolls in the oven, I went out to the garage and installed the upper centering ring with the OneBadHawk Y harness secured to it. The booster coupler was then used to slide the centering ring into position, before it to was firmly epoxied in place, and once that was done, a stiffy tube was epoxied in place inside the coupler to reinforce the joint.





Then this afternoon, I decided to locate and install the Aeropack retainer on the aft centering ring. A 4" coupler was used in place of a 98mm motor case to locate the retainer. Once it was all drilled up, the inserts were installed, and the retainer test fitted. The whole assembly then came back off will will be final installed after paint.

 

[krislhull]

After a hiatus of several weeks due to the chaos that is work, and also just life in general, I realized this past weekend that I have just shy of two months left to get this build completed! I do not have a whole lot left, but what I do have is somewhat time consuming. Fist up, I received an order from Wildman that included a Additive Aerospace altimeter sled for the av bay, as well as a second one for the tracker. I also broke down and decided to buy a dedicated drogue for this rocket, instead of sharing one with my L3 build, so a Skyangle Cert 3 drogue was included as well.

First up on the checklist for work was to rough complete the altimeter bay. I drilled out the mounting holes for the new all threads in the bulkheads, and I also installed fiberglass bulkplates on the outsides of the plywood plates to serve as further protection from ejection gasses. I will complete the altimeter installations this coming weekend, and also drill out and locate the holes for the arming screws and the vent holes.

Because of the size of this beast, I want the rocket to be modular, so it will break down into its basic airframe sections, and as such they will be bolted together in the field. Today after work I drilled locations for 8 bolts at the lower joint, to in line with each fin, and installed blind flange nuts with epoxy. after the epoxy was cured, everything was test fit, and it fits like a glove! I also took the time to install the mounting location for the upper rail guide.

 

[loopy]

Building it so that the body tube comes off of the booster section was one of the best decisions I made with this rocket...lol...MUCH easier to move around and transport.

 

[krislhull]

Building it so that the body tube comes off of the booster section was one of the best decisions I made with this rocket...lol...MUCH easier to move around and transport.

Agreed! When you do not have a large vehicle or a trailer, a modular rocket is a dream come true! I am actually debating on adding another airframe section onto this beast now, and maybe making it a couple of feet taller, since the motor it is destined to fly on looks like it will bust the waiver at the launch site. So we will have to see what happens. Need to run a few sims tonight and make a decision.

 

[loopy]

Agreed! When you do not have a large vehicle or a trailer, a modular rocket is a dream come true! I am actually debating on adding another airframe section onto this beast now, and maybe making it a couple of feet taller, since the motor it is destined to fly on looks like it will bust the waiver at the launch site. So we will have to see what happens. Need to run a few sims tonight and make a decision.

What motor, and what is the waiver?

 

[krislhull]

its a 9,000ft waiver, and it will be a 98mm EX motor. Sims out to 9,500 feet with my preliminary rough estimated weights at the moment.