Loc Goblin Thread

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Well, centering rings are sanded, and fresh glue purchased (Titebond II, Titebond III, and Titebond Quick and Thick). Rings have been test fit into tubes, and tubes peeled where rings and fins will be attached. T nuts are installed into rings and soon assembly will begin!
 
Know way you purchased it last weekend and your building it already. How did it move to the top of build pile?
 
4" version is ready to fly this weekend. Just sneaks in under the Class 1 limit of 3.3lbs loaded. More to come...

In the meantime, here's the comparison photo: 5.5" extended Cletus in a Goblin costume, 4" Loc Gobin, and Semroc's repro of the BT-55 Estes original.

39968619405_f8a9af19a4_z.jpg



Sweet!
 
Looks great Eric, I like the Monokote treatment, and the BT split. An amazingly quick build! I look forward to seeing where LOC-N-Mount shows up next. So... you hang out by the tracks often? ;)
 
Eric, for some reason any pictures you posted after the 15th won't pass through my work firewall. (all previous ones are fine)

Did you just switch photo upload/hosting methods?


Don't want to complain, I just like seeing the photos lol
 
IMG_1521500240.369871.jpg

I've got a Goblin I have been meaning to get built for a while. Not sure how old it is, but I'm guessing it was made in the seventies?
 
4" version is ready to fly this weekend. Just sneaks in under the Class 1 limit of 3.3lbs loaded. More to come...

In the meantime, here's the comparison photo: 5.5" extended Cletus in a Goblin costume, 4" Loc Gobin, and Semroc's repro of the BT-55 Estes original.

39968619405_f8a9af19a4_z.jpg

Wow, that looks terrific!:bat:

From the picture the 5" Goblins fins look to be a fine match. The nose cone actually looks to be a better match too!

The Cletus fins are not quite to scale as the Goblin. But Thank You for fueling my ADD/OCD problem and now we may just have to re-brand the Big-C. Should we give it the same treatment we did to the 4"? 75/54/38 mm adaptor rings and loc-n-rings? We're all ears over here!!! LOL

The "Big Cletus" is a great name, that puts smile and laughs on peoples faces.

I'm not sure how useful 75mm motors would be in there.
It might be cool to have some cluster options like the Warlock. I don't see that option in any of the 5" inchers currently It would be challenging with the loc-n-rings.

You guys are killing me! There are so may kits I want to build. My build pile is getting big, but I think I am just going to admit I am only collecting Estes kits ( and that might be a good investment at this point), and actually building the bigger stuff.
 

Thanks!

Looks great Eric, I like the Monokote treatment, and the BT split. An amazingly quick build! I look forward to seeing where LOC-N-Mount shows up next. So... you hang out by the tracks often? ;)

Thanks Paul! Yessir, this thing almost flew together!!!

Regarding tracks...YES! They only get traveled once or twice a week now by trains....slow moving short trains that idle by and return after 30 minutes or so. I know a guy that lives along those tracks:wink: I like the semi-different background!

Eric, for some reason any pictures you posted after the 15th won't pass through my work firewall. (all previous ones are fine)

Did you just switch photo upload/hosting methods?


Don't want to complain, I just like seeing the photos lol

Hmmm, I switched from Photobucket to Flickr after the 3rd Party Hosting debacle...but that was back in November, 2017. I'll try posting the same photo in two different ways and send you a PM to see if it makes a difference.

Anybody else having issues seeing photos I posted?

View attachment 341184

I've got a Goblin I have been meaning to get built for a while. Not sure how old it is, but I'm guessing it was made in the seventies?

Sweet! No time like the present! A built vintage kit is worth more than a musty bag of parts, in my opinion!:wink: Do it!

Wow, that looks terrific!:bat:

From the picture the 5" Goblins fins look to be a fine match. The nose cone actually looks to be a better match too!



The "Big Cletus" is a great name, that puts smile and laughs on peoples faces.

I'm not sure how useful 75mm motors would be in there.
It might be cool to have some cluster options like the Warlock. I don't see that option in any of the 5" inchers currently It would be challenging with the loc-n-rings.

You guys are killing me! There are so may kits I want to build. My build pile is getting big, but I think I am just going to admit I am only collecting Estes kits ( and that might be a good investment at this point), and actually building the bigger stuff.

I dig the 5.54" Long nosecone. My first "really big" rocket back in 1999 used one; it's been a sweet spot ever since! Though the tip is "pointier" than the original Goblin, I think it looks nice!

Motor mounts: the stock Cletus comes with a single 38mm mount. I installed an inline trio of 38mm mounts. An example flight which was a lot of fun was a J1001 Blue off the pad airstarting two I315 Skidmarks 2 seconds into the flight! One could install a cluster of five 38's, or a 54 and some 29's around the outside....lots of good options. The Loc boys can help you with your desired mount.

Fins: They're close. For the nit-pickers, the leading edge sweep angle is a bit greater and the span a bit less. For a high power rocket of it's size, it's definitely a better fin shape; and certainly "close enough" for me. The longer root chord and reduced fin span reduced the likelihood of flutter; so I'll take it!
 
Apologies for the temporary silence...illness kicked me in the head for a few days. Back to it!

Quick Recap: The Loc gang spanked their Goblin on an Aerotech J425 Redline on 3/10; that was fun! I wanted to test the other end of the spectrum; hoping that the completed rocket would be light enough to be a small field Class 1 (NO FAA WAIVER REQUIRED!) flyer, yet strong enough to handle a JmaybeK motor. After covering and doing the internal assemblies on page 1 of this thread, here's the remainder of the quick build.

Glue in motor mount, tuck in the tabs. Not much explanation necessary. Mix up a batch of 5 minute epoxy (I like to live dangerously!:cool:), apply a ring or two to the ID of the airframe, part the slits, install motor tube until the fins run into the forward end of the fin slots, tape up the rear.

40046375845_bf10888e0a_c.jpg
[/IMG]

Optional Step: external fillets. Yes, I said optional. All the necessary strength is in the solidified, interlocking motor mount/fin assembly, so external fillets aren't really necessary. I do them here for two reasons:

1. I want to seal the edges of the covering and any gaps that occur at the leading and trailing edges of the fins if you're goofy enough to bevel the fins.
2. In case you're sly enough to *intentionally* slightly misalign the centering rings which *intentionally* imparts a slight fin angle which *intentionally* imparts a nice stability-increasing roll rate for your Goblin. Then you might *intentionally* have to fill any slight gaps that might exist. Yep, I *meant* to do that. :rolleyes:

Without further ado, I kinda dig the way 5 minute Bob Smith epoxy dries clear and seals up covered rocket surfaces masterfully. No tape, no pvc pipe pullers or fancy sticks; just approximately the right amount of epoxy, a steady finger and some alcohol (to wipe up your sticky finger and messy rocket).

39131180250_50055f15c8_c.jpg
[/url][/IMG]

Throw on some included decals (YAY!!!) and take a completed dry weight. Not bad! Note, I build LIGHT and always consider saving mass wherever. That said, I built this STOCK (ok, beveled fins).

40046377705_a53e99b6e3_c.jpg
[/url][/IMG]

Fully prepped with the ultimate G motor (yes, a real G motor)...the G69 Skidmark.

40931073421_e5e15b3207_c.jpg
[/url][/IMG]

Also a good time to address dhbarr's suggestion:
I like to follow up with a thin slice of coupler, but that's just a preference.

Not a bad idea at all! With the motor mount adapter system, you might run into clearance problems in doing so. Simple solution would be to reduce the OD of the adapter's thrust ring a bit using a dremel. Because the fin's root touched the airframe nearly all the way to the rear of the tube, I didn't find any additional reinforcement necessary. Not sayin' it can't or shouldn't be done...:smile:

Now for the true moment of truth. My name and signature is on the local land use permit as the responsible party...I'm not bending no rules. Class 1 weight limit is 1500g/53oz/3.3lbs. Fully prepped with a G69SK:

40940864371_5e7b13b652_c.jpg
[/IMG]

51.7oz: Green Light!
 
So if careful, the 4" Goblin can be built light enough for Class 1 Waiver-less launches: Cool.

Just so happened to have one of those recently. First up, the BT-55 original sized alongside the 4" Upper.

26067998827_800ffdc5b3_c.jpg
[/url][/IMG]

First Flight: G69 Skid: Photo off the rail wasn't great...focus was off and the rail was in the way. So here she is part way up. Love that little motor!

40046395405_8b805bcbf6_c.jpg
[/url][/IMG]

...and recovered in happy fashion: Digging the tweaks to the Loc chutes by the way....:p

40940906391_7d9e57efd5_c.jpg
[/url][/IMG]

The G69 flight was great, and majestically rose to probably 800' or so; landing 35 yards away. Great for small field demos. But what about a baseball field flight????

Okay, Aerotech F50-4T. Once again, under the weight limit (more so this time). The F50 was plenty punchy off the pad and the 4" Gob lumbered to 400' or so.

40046395265_5d71acecf1_c.jpg
[/IMG]

40222369834_fc31d07bcf_c.jpg
[/url][/IMG]

The 4 second delay was right on, popping the laundry right at the top. She landed 6' away from the LCO table...nice. I'd fly this thing off a baseball diamond if needbe.

I like mine; and will be testing the other end of the motor spectrum next (date tbd). In the meantime, what are y'all doing with yours????:D
 
Excellent flights! I love the G69 too. My daughter wants a fat rocket, but she isn't old enough for Jr. L1 yet, so I need to keep it pretty light. I think this just moved to top of the list.
 
In the meantime, what are y'all doing with yours????:D

Well, I forgot to take a picture :( , but all the fins are on mine also. The fillets at the fin to mmt joint are next, then like Eric, I'll stuff the whole assembly into the a$$, er, I mean body tube... Yeah, that's it... Unlike Eric, I'll have to actually use paint on mine :sigh: Were there any other colors for the Goblin, or just the yellow?

On a side note, while installing the centering rings and using a fin to align them, I put the fins in down side up so I could stand the motor tube up. I might have to get another kit... With the fins that way, it starts to look like my old NCR Archer XL. Hmm, add some strakes,a lick of white paint, some Stickershock, and I've a lazy man's NCR Archer clone...
 
Great flights... Beautiful rocket. Mine finally came in today. I think it took the slow ground freight truck. Time to start building.

0321181414_HDR.jpg
 
Last edited:
So,
To jump into Eric's thread...
All fins are on. Internal fillets are on and drying. Next step is to slit the BT and stuff that sucker in...
So, without further ado. A picture...

IMG_0721.JPG
 
So, I got the Goblin all painted up and put the decals on today.
Then I decided to put the nose cone on and see the finished product. Now, in my defense, this is the first Goblin of any size that I've ever built. I've also never built a Der Red Max of any size yet either... So, there I was, admiring my finished product (or so I thought), and then I looked closer at the LOC picture... Well crap. So I guess I start sanding, because who doesn't like sanding...

IMG_0750.JPG
 
Last edited:
Nice Goblins! It's always been one of my favorite rockets. I might snag one and build a pay load extension and dual deploy it. I could fly it as a 4' Goblin and as a 6 ft. "Tall Goblin". Hmmm..., That's mighty tempting and I have all the parts for the extension on hand. And my birthday is coming up.....:)
 

Attachments

  • .75 in burr.JPG
    .75 in burr.JPG
    15.7 KB · Views: 137
  • 9-16 in burr.JPG
    9-16 in burr.JPG
    15.4 KB · Views: 130
Last edited:
Eric,

Can you post up a few pictures on how the motor mount adapters work? Maybe a pic series of the Goblin with just the 54mm open, then inserting and securing the 38mm, then mounting and securing the 29mm? I'm trying to wrap my head around the process. The LOC instruction sheet doesn't really go through the sequence. I guess it's intuitive when you have it all built and in front of you, but I'm at the begging you or Justin to bevel my fins for me stage. :D
 
Last edited:
Well, 3/4" or 9/16" ? As the man said..."I gotsa know"...

Short answer, all I ave ever used was the 9/16, but either should work. If I recall correctly, the red bit was coarse and blue was fine, I'd look for that same bit in blue if possible.
 
Eric,

Can you post up a few pictures on how the motor mount adapters work? Maybe a pic series of the Goblin with just the 54mm open, then inserting and securing the 38mm, then mounting and securing the 29mm? I'm trying to wrap my head around the process. The LOC instruction sheet doesn't really go through the sequence. I guess it's intuitive when you have it all built and in front of you, but I'm at the begging you or Justin to bevel my fins for me stage. :D
You bet! Give me a few days...
 
Back
Top