LOC Precision 4" Goblin Level 1 Certification build thread

[SPStorm]

Just starting in HPR and chose the LOC 4" Goblin for my level 1 certification build. All feedback is welcome.



I plan to build the motor mount and attach fins outside the airframe (not sure if I am using the correct term - main tube, body tube?) including epoxying the internal filets while outside the tube. Once completely cured I will cut slits in the bottom of the fin holes to slide the assembly in.

Here are some decisions I have made but could change:
Motor: I am thinking the 54mm AeroTech I229T but that could change for sure.

Motor Retention: AeroPak 54L retainer instead of the included clips to hold the motor in.

Motor Casing: I am thinking of buying a larger motor case with the RAS spacer system so that I can use it for more grains in the future. I saw the 5412S at Wildman Rocketry and like the idea having a good amount of options with just two casings. From what I can tell, I'll have the ability to run all AeroTech 54 RMS motors from 426 to 2800 with this. Please let me know what you think of this decision because I have no clue if it would be better to just buy a 54426 now and keep buying as need going forward.


Here is a google drive link to my first step video:

 

[Hobie1dog]

to the forum

 

[thzero]

I'd sim it first with OR.... yes, you can probably run all those motors those cases allow, but not all motors perform the same. Usability seems better option, but smaller motor in a longer case means more aft weight and just weight overall - thats where sims can help make decisions.

 

[SPStorm]

Part 2

Completed motor mount internal fillets on fins and centering rings with west systems 105/206 and added 406 silica filler to thicken for centering ring fillets. I filled the z-clip t-nut holes up with epoxy because I think it will look cleaner with the AeroPak retainer. Will let set overnight and probably start the next steps tomorrow night.

I have changed my mind on the motor and casing. Currently I plan to buy the aerotech 54/1280 case and the RAS to adapt it for the 54/426 I170G. I like the idea of being able to use 1,2 or 3 grains with 1 case and can use the spacers in a longer case for a different rocket.

Link to video of the current progress:

 

[SPStorm]

Part 3

Tried to use 3M 907 bondo on the airframe to fill in the spirals. I don't have confidence that it will help much. I feel like finishing the rocket is a real art and I wasn't granted this gift. I really want to make this rocket look good but will be ok if it looks decent from 30 feet away. I attached the shock cord to the eyebolt mount, mixed up some thick epoxy and spread it inside the airframe just below where the centering rings final position would be and slid the motor mount in. I used some clamps to hold the bottom of the airframe against the aft centering ring. Is this an ok way to do this. I slid the motor mount and and realized I didn't plan how I was going to hold the cut end of the airframe in place. I ran to the garage and grabbed a bunch of clamps. Seems like it is going to work. I guess Ill find out in the morning . I hope to do the the exterior fin filets tomorrow during breaks from work and then primer the next night. I really like this kit. I don't think its purely sentimental (I loved the Estes goblin), I feel the quality and how easy it is to build puts the LOC far above the original in my book.

Link to google drive video of current state of project:

 

[Upsrocketman]

Part 2

Completed motor mount internal fillets on fins and centering rings with west systems 105/206 and added 406 silica filler to thicken for centering ring fillets. I filled the z-clip t-nut holes up with epoxy because I think it will look cleaner with the AeroPak retainer. Will let set overnight and probably start the next steps tomorrow night.

I have changed my mind on the motor and casing. Currently I plan to buy the aerotech 54/1280 case and the RAS to adapt it for the 54/426 I170G. I like the idea of being able to use 1,2 or 3 grains with 1 case and can use the spacers in a longer case for a different rocket.

Link to video of the current progress:

Don't forget that the 426 case and loads use a smaller aft closure than the rest of the 54 cases. This is going to be a sweet rocket when it's done! I just picked up a wildman goblin that I will be building to take to Ldrs in July.

 

[tsmith1315]

I feel like finishing the rocket is a real art and I wasn't granted this gift

Getting a nice finish is largely dependent on how long you’re willing to continue the sand, spray, sand cycle.

 

[Banzai88]

Getting a nice finish is largely dependent on how long you’re willing to continue the sand, spray sand cycle.

Then add to that 3-5 levels of liquid polishing, if one is so inclined.

 

[waltr]

Yea, I did my L1 cert with this Goblin. Great kit and great flier.

Do watch the LOC video one building and also search forum here for the LOC Goblin build threads.

One caution, Pay attention to the motor adapters rear ring attachment. This ring to MT needs to hold up to the full motor thrust.

 

[Hobie1dog]

What color scheme is it going to be?

 

[Donnager]

Getting a nice finish is largely dependent on how long you’re willing to continue the sand, spray sand cycle.

Then add to that 3-5 levels of liquid polishing, if one is so inclined.

150 grit final sanding = I sanded it
220 grit final sanding = I smoothed it, but there's lots of scratches--Good at 5-10'
330 grit final sanding = If I choose good paint, I may be able to cover these scratches, but will have to spray thick. Usually where I stop
440 grit final sanding = This is where I wish I would have stopped at 330. I stop here.
600/800/1000/2000+ grit sanding = Ok, So I will really, really stop at 600..... This is wet sanding show-style bodywork territory for glassy finishes. I don't plan to make this level of effort for anything I am going to let touch the ground. If I do this, it will be a shelf model that will see nothing rougher than a microfiber or a felt lined stand in its future

 

[SPStorm]

Don't forget that the 426 case and loads use a smaller aft closure than the rest of the 54 cases. This is going to be a sweet rocket when it's done! I just picked up a wildman goblin that I will be building to take to Ldrs in July.

Thank you! I was wondering about this. Ill make sure to buy the small nozzle aft closure and pick up the regular one later when I need it.

 

[SPStorm]

What color scheme is it going to be?

I was thinking of trying to match the original colors but ended up with a different paint.

This is the paint I bought, no real reason other than it caught my eye at the store.



I am planning on using this in place of the original yellow and keep the original black parts (1 fin, nose cone, band and decals). I am not fully committed to this though. I was thinking of using the decals as a mask to have a different secondary color. Please let me know if a different primer/paint brand would be better.

 

[SPStorm]

Part 4

Did the exterior filets throughout the day...take a 15 min break from work and do a pair, come back 3 hours later and repeat. Going to let it cure another day and do some sanding/primer tomorrow. Got my paint booth ready.

 

[Dave S.]

I have used that primer and paint combo a number of times. Closest thing I have to your color choice is an NCR Hobgoblin that is sea blue with a bright red nose cone.

 

[SPStorm]

Part 5

2 coats of primer on, sanded in between with 220 grit. Ran out of primer, need to buy more. I think I need to get some higher grit sand paper too. I currently only have 60, 80, 120, 150 and 220.

 

[Hobie1dog]

looking good

 

[SPStorm]

Part 6

Put on a 3rd coat of primer, sanded with 600 grit and applied first color coat. I can still see airframe spiral and nose cone seams. I thought I preped them enough but now I don’t think so. I think I will just live with it, but if it bugs me enough I may sand and fill them in better.

 

[SPStorm]

When looking at the rocket today, I realized I didn’t install the rail buttons before I epoxied the motor mount assembly in place! I was so mad at myself, until I searched these forums and found I can drill holes and put some JB Weld in to secure instead of using a nut on the inside. I ordered the motor and case I’ll be using.
AeroTech 54mm

• I170G-10A
• 541280C
• 54RAS
• 54ACSN

Both Wildman and AeroPak were out of stock for 54mm retainers so I ordered LOC Precision ones, I didn’t even know they made their own. Glad they had them.

I have some things I forgot to order: chute protection (Nomex), possibly a shock cord protector, the rms delay adjustment tool, grease and some initiators/first fire motor lighters.

 

[TRWXXA]

When looking at the rocket today, I realized I didn’t install the rail buttons before I epoxied the motor mount assembly in place! I was so mad at myself, until I searched these forums and found I can drill holes and put some JB Weld in to secure instead of using a nut on the inside. I ordered the motor and case I’ll be using.
AeroTech 54mm

• I170G-10A
• 541280C
• 54RAS
• 54ACSN

Both Wildman and AeroPak were out of stock for 54mm retainers so I ordered LOC Precision ones, I didn’t even know they made their own. Glad they had them.

I have some things I forgot to order: chute protection (Nomex), possibly a shock cord protector, the rms delay adjustment tool, grease and some initiators/first fire motor lighters.

I ordered a set of surface mount rail guides to replace the 1/2" launch lugs on my 20 year old, 4" Goblin. Might be a stronger alternative to epoxying rail buttons onto a cardboard tube.

https://giantleaprocketry.com/products/acme-rail-guide-3-00in?variant=37741098598572
I suffer from the same affliction as you, which lead me to placing 3 separate orders to Wildman in 5 days.
The one I received yesterday had the 54mm AeroPak in it. Sorry about that.

 

[Titan II]

Might be a stronger alternative to epoxying rail buttons onto a cardboard tube.

It would be easily to hit the upper and lower centering rings (1/4"?). Another alternative are two well nuts.

 

[TRWXXA]

It would be easily to hit the upper and lower centering rings (1/4"?). Another alternative are two well nuts.

Maybe a well nut in the unreachable area of the fin can, but I'd worry about it being a snag point for the recovery system if used in the main body tube. A weld nut would be lower profile.

Sifting through all the alternative solutions to problems is part of the fun.

 

[Titan II]

Maybe a well nut in the unreachable area of the fin can, but I'd worry about it being a snag point for the recovery system if used in the main body tube. A weld nut would be lower profile.

Sifting through all the alternative solutions to problems is part of the fun.

It is obvious you do not put it in a location to snag anything. Immediatly below the upper ring would be fine.
Screwing them into the rings is logical. Have fun.

 

[Art Upton]

When looking at the rocket today, I realized I didn’t install the rail buttons before I epoxied the motor mount assembly in place! I was so mad at myself, until I searched these forums and found I can drill holes and put some JB Weld in to secure instead of using a nut on the inside. I ordered the motor and case I’ll be using.
AeroTech 54mm

• I170G-10A
• 541280C
• 54RAS
• 54ACSN

Both Wildman and AeroPak were out of stock for 54mm retainers so I ordered LOC Precision ones, I didn’t even know they made their own. Glad they had them.

I have some things I forgot to order: chute protection (Nomex), possibly a shock cord protector, the rms delay adjustment tool, grease and some initiators/first fire motor lighters.

You will be fine. Rail Buttons are usually the last Item I put on a rocket, even an Estes Rocket [micro & mini buttons]

Even my L3 rockets did not have a nut on the inside of the body tube, but I would try to get them into the centering ring.

 

[Rocketjunkie]

I use these https://www.mcmaster.com/products/nuts/nut-type~adhesive-mount/ Ugly but works. Bend flange to fit body tube. 8-32 for 1010 buttons.

 

[SPStorm]

Part 7

I have decided to be done with the color coats. It’s not quite where I wanted but its ok for me. I am going to let it dry a couple days before masking/painting the one black fin. I think I have learned a couple things that will help with painting my next rocket.

Current state video link:
https://www.idrive.com/idrive/sh/sh?k=j9f1g6j0l4

 

[SPStorm]

Added vinyl decals

 

[SPStorm]

Decals on, 4 coats of clear. Almost there.