Loc Goblin Thread

[Nytrunner]

I've been thinking about cutting the base off and putting in a bulkhead with an I bolt, but am concerned about epoxy not sticking to the plastic nose cone. I'd like to use the cone for a tracker av bay at some point also.

You can help yourself out by really scuffing the interior surface, cutting ex marks with an xacto or little dips with a dremel, and using a thick epoxy like rocketpoxy. That was Eric's advice to me when I had to bond stuff to that slippery polyprop cone material. You can also place the bulkhead beyond the shoulder and use that internal lip to your advantage (just need to squeeze the shoulder a bit to get it in there)

 

[rrobe99999]

I am building a 4" Goblin from scratch and printing my own decals. I need help getting the decal scale correct and could use some measurements from you guys that built the LOC kit. How wide is the black stripe? How tall is the "3"? How tall and wide is the "GOBLIN" lettering? Thanks

 

[JonathanOtt]

I am building a 4" Goblin from scratch and printing my own decals. I need help getting the decal scale correct and could use some measurements from you guys that built the LOC kit. How wide is the black stripe? How tall is the "3"? How tall and wide is the "GOBLIN" lettering? Thanks

Sending you a private message. I got what you need.

 

[ECayemberg]

Sorry if I'm grumpy this morning....

1. This is a Loc Goblin thread.
2. Loc obtained rights from Estes to release an upscale version. Kit is currently available and a great value (very complete and super quick/easy to build).
3. Decals are included with the kit; or available from Stickershock23 for $18. Lots of quality vinyl for little price IMO.
4. I love scratch building. I've even built a few clones. I'm all for do-it-yourself'ers and scratch building...but cloning a currently available kit by asking others who have paid for the kit for actual measurements is poor practice, again in my opinion.

You want rocket vendors around? Please support them, or they disappear.

Again, not meant to be an attack, and rarely do I get grumpy. There are a wide variety of opinions on this matter out there, and my opinion is just one opinion. I suspect if you've been on or close to the manufacturing side of things, you probably agree with me. If not, maybe not.

Regardless, have fun with your Goblins! Got mine loaded with a G69 skid for a dusk launch this weekend!

 

[rrobe99999]

Yes, I support our vendors and am building my Goblin with LOC tubes and NC in the same manner as my other Estes upscales. I cut my own rings and fins and print my own decals if they don't have white (I purchase white decals from Stickershock). Recovery harnesses, chutes and electronics are shared amongst my fleet. Most of my rocketry budget is spent on commercial motors. If I spent more money buying stuff that I already have or could make myself, I would have less money for motors and couldn't fly as much. I appreciate the wealth of information that is freely shared on this forum and the great advice I get from TAPs when advancing further into new challenges. If someone considers any of my requests for info to be stupid or poor practice they may simply ignore it.

 

[gldknght]

You can help yourself out by really scuffing the interior surface, cutting ex marks with an xacto or little dips with a dremel, and using a thick epoxy like rocketpoxy. That was Eric's advice to me when I had to bond stuff to that slippery polyprop cone material. You can also place the bulkhead beyond the shoulder and use that internal lip to your advantage (just need to squeeze the shoulder a bit to get it in there)

Yeah, I always rough up the plastic when epoxying wood to plastic but have never used this in a high stress area before. Anyway, I cut off my base, roughed up the plastic, and epoxied in my bulkhead. I left a little bit of the radius curve at the base on, so the bulkhead physically can't pull straight out of the bottom of the nose:




It's not my cleanest cut on plastic, but I was doing it with a pocket knife so...

 

[roytyson]

I do something similar, only I push my centering rings up the nose cone and glue to the backside of the tube sleeve. if the get the size right and epoxied correctly all the shock load is put on the step of the nose cone sleeve and not relying on the epoxy to take the load.

 

[gldknght]

I do something similar, only I push my centering rings up the nose cone and glue to the backside of the tube sleeve. if the get the size right and epoxied correctly all the shock load is put on the step of the nose cone sleeve and not relying on the epoxy to take the load.

Mine does pretty much the same thing. My bulkhead was so tight, I had to sand the outside of the nose cone base a bit to make it fit in the body tube again. The base of the cone will have to break apart in order for this to separate.

 

[DAllen]

So here's a question for those that have built a 7.5" Goblin...How in the world do you get the 75/5120 case to fit in it? Looking at the LOC web site I see they have a video from a M1275 flight and the pictures don't appear to have the casing awkwardly sticking out the aft end yet it seems like with a 30" fin can and a 26" long motor there just isn't enough room with the standard ebay...what am I missing here? There's soooo much room in a 7.5" ebay I suppose letting the motor stick halfway up into it is a possibility...

 

[Rocketjunkie]

I built a 7.5" Goblin in 2010 before the kits came out. It was also before the 'head end deploy' kits came out. Main is in the nose cone, nose separates at apogee, altimeter bay ejects from nose cone pulling out the main. I can get a 98/15360 case in it. This is how I built it https://www.rocketryforum.com/threads/almost-a-goblin.8709/

 

[Wallace]

Head end deploy makes perfect sense to me. Especially on short{er} rockets that'd end up w/lead up front anyway. I likey..Also, what are your opinions on the Bluetube? One of the few materials I've yet to experiment with..And btw, get a haircut

 

[JAYatLOC]

So here's a question for those that have built a 7.5" Goblin...How in the world do you get the 75/5120 case to fit in it? Looking at the LOC web site I see they have a video from a M1275 flight and the pictures don't appear to have the casing awkwardly sticking out the aft end yet it seems like with a 30" fin can and a 26" long motor there just isn't enough room with the standard ebay...what am I missing here? There's soooo much room in a 7.5" ebay I suppose letting the motor stick halfway up into it is a possibility...

Morning DAllen - So our 7.5" Ebay now only utilizes 7.5" of room for electronics. The other 7.5" is a void meant for more room for recovery or for a longer motor to stick up the booster. Essentially you would have room for a 29" motor w/o any sticking out the aft. I did fly an EX M in mine as well that was 36" long 75mm. I stretched the airframe 8" to make that work. But yes, possible!!

 

[Wallace]

Morning DAllen - So our 7.5" Ebay now only utilizes 7.5" of room for electronics. The other 7.5" is a void meant for more room for recovery or for a longer motor to stick up the booster. Essentially you would have room for a 29" motor w/o any sticking out the aft. I did fly an EX M in mine as well that was 36" long 75mm. I stretched the airframe 8" to make that work. But yes, possible!!

Partial doughnut av bay of sorts? I love ingenuity!!

 

[DAllen]

Morning DAllen - So our 7.5" Ebay now only utilizes 7.5" of room for electronics. The other 7.5" is a void meant for more room for recovery or for a longer motor to stick up the booster. Essentially you would have room for a 29" motor w/o any sticking out the aft. I did fly an EX M in mine as well that was 36" long 75mm. I stretched the airframe 8" to make that work. But yes, possible!!

Sweet! Problem solved!!!

 

[Joshua F Thomas]

Necroing thread back from the dead, because I just got one of these. Gonna start building soon. Lots of useful info in thread.

Can I get some motor recommendations for this? With a 1000 ft altitude maximum? I'm sim-ing but previous experience is helpful.

Thanks in advance.

 

[Lloyd Leichentritt]

Here is mine that I got my Lvl 1 cert in May, what a great build and launching it was so much fun...

 

[Joshua F Thomas]

I spy, with my little eye, a very large Der Red Max hiding in the background....

 

[Lloyd Leichentritt]

I spy, with my little eye, a very large Der Red Max hiding in the background....

Yep

 

[Joshua F Thomas]

So an OR sim with the 4" Loc Goblin and Aerotech RMS-29/40-120 shows me these options as reasonable: G53FJ-5, G64W-4, G76G-4

423 ft, 607 ft and 620 ft respectively. In the $20+shipping (no hazmat) per launch range.

 

[ECayemberg]

So an OR sim with the 4" Loc Goblin and Aerotech RMS-29/40-120 shows me these options as reasonable: G53FJ-5, G64W-4, G76G-4

423 ft, 607 ft and 620 ft respectively. In the $20+shipping (no hazmat) per launch range.

I would fly any of those motors without hesitation on a normal day. Stick with the 64 or 76 for breezy days to keep the trajectory more predictable. Enjoy!!!

 

[ThePlmbr]

Hi Eric. I hope you and your family are all doing well. Miss seeing everyone, during this strange times. Stay safe. Greg Olson

 

[Joshua F Thomas]

Here is mine that I got my Lvl 1 cert in May, what a great build and launching it was so much fun...

What motor did you use for your level 1?

 

[Lloyd Leichentritt]

What motor did you use for your level 1?

I when with a lower motor an H112J. My JL Altimitor 3 was not connecting so not sure on the altitude but OR calculated it to be 1998". I poped my chute a 300' and landed about a100' away. I was a great flight.

 

[Joshua F Thomas]

Slow start for me on my Goblin. I put together the 29mm and 38mm adapters. I'm using T-88 epoxy and that stuff takes *forever* to finish curing - the box says 72 hours for full cure! - so I'm waiting on some 5-minute Bob Smith epoxy to make my life a little easier.

I'm going to eventually L1 this. One of the things I want to do is be able to add more mass to do purely to keep the altitude down. My club member tried to L1 his and it drifted out into the swamp and still has yet to be recovered! I won't be using dual deploy nor the chute release; less complexity means less things to fail on an L1 attempt. So, I'd like to try to push the altitude down to keep the drifting down.

Any suggestions on how to temporarily add mass to the Goblin? It doesn't come with a payload bay. I suppose I could cut the nose on the bottom and add some type of access door that closed, and put clay inside whenever I need more mass. Thoughts?

 

[dr wogz]

Joshua, my opinion?

• BSI 30 minute over the 5 minute stuff. The longer cure time gives it more time to seep into the cracks & pores & voids of the paper & wood; a stronger bond.
• Add mass as needed for the largest motor you intend to fly it on. And, there are methods to add this weight. My preferred method is two holes thru the tip of the NC, then stick wood dowels thru these holes, then add the required mass of BBs & epoxy. Tap down. Trim & sand the dowels on the exterior on the NC. Mine has a few ounces, not too much..
• Don't rely on the loop molded in the NC. Cut two holes in the base of the NC, and run a strap thru the holes & tie it off.. (more area to absorb the loading) use one of these holes to add the nose weight.
• Ditch the the included adapters, and go with an Aeropak adapter & retainer (or similar). Don't bother with any motors smaller than 38mm (slightly less weight in the end, and you can use the adapter in other models: less 'stuff' to carry around). If you are serious about L1 (and possibly L2), you'll be getting into 38mm motors soon enough..

I fly mine mainly on H and up motors.. I have other rockets for the smaller 29mm G & H motors.. I feel the 4" Goblin is just a tad over the "flies on 29mm G motors" line..

 

[Joshua F Thomas]

Joshua, my opinion?

• BSI 30 minute over the 5 minute stuff. The longer cure time gives it more time to seep into the cracks & pores & voids of the paper & wood; a stronger bond.

Does the BSI stuff cure to not-tacky any faster? Because it's a real pain to try to work on stuff with slightly sticky epoxy. I'd like to be able to add all my fins at once without having to wait for the long cure time in-between.

Add mass as needed for the largest motor you intend to fly it on. And, there are methods to add this weight. My preferred method is two holes thru the tip of the NC, then stick wood dowels thru these holes, then add the required mass of BBs & epoxy. Tap down. Trim & sand the dowels on the exterior on the NC. Mine has a few ounces, not too much..

The rub here is that if I add mass for the largest motor I ever use, I either a) limit myself a largest motor or b) add so much mass that I reduce the performance on lower motors AND add over-stability.

Adjustable mass would be a lot better. I'm considering making a short payload bay, with a nut-and-bolt system to which I can install heavy washers. This would allow me to dial the mass in directly.

Don't rely on the loop molded in the NC. Cut two holes in the base of the NC, and run a strap thru the holes & tie it off.. (more area to absorb the loading) use one of these holes to add the nose weight.

Yeah, that's on my to-do list.

Ditch the the included adapters, and go with an Aeropak adapter & retainer (or similar). Don't bother with any motors smaller than 38mm (slightly less weight in the end, and you can use the adapter in other models: less 'stuff' to carry around). If you are serious about L1 (and possibly L2), you'll be getting into 38mm motors soon enough..

I'm not doing L2 on this kit. I'll do something else for that. I'm also sticking to 29mm motors for now due to cost. G motors are less expensive (as these things go) and I can fly them anywhere without a waiver, so that will be my default.

I feel the 4" Goblin is just a tad over the "flies on 29mm G motors" line..

Sims aren't perfect, but it sims very nicely on 29mm G64 and G76, for about 600-630 feet. This is excellent for my tree-filled New England, where large empty spaces are hard to come by.

 

[jd2cylman]

I’ve flown my Goblin on small I motors to K motors. No nose weight in any configuration. Just fly it.

 

[dr wogz]

Building isn't a race.

I will typically do a fin per night.

I find the weight/ mass difference needed for a wide range or motors is minimal. (You don't need to add pounds to make up for the difference between an H180 & J420) You can, also just add a mass to the end of the NC to make up any difference (i think we'e all done that: add a wrench or a .. to the end of the shock cord to get a balance.. even a few nuts & bolts can be enough) We see a number of people try to get one rocket to cover a wide range of flight characteristics, motors, intents, etc.. so they never really shine..

Don't forget, that for 29mm motors you're using BOTH adapters.. And that's added weight in the end you don't want added weight! Hence why I say go 38mm or larger, and the Aeropack type adapter..


New England?! where abouts?

 

[Joshua F Thomas]

Don't forget, that for 29mm motors you're using BOTH adapters.. And that's added weight in the end you don't want added weight! Hence why I say go 38mm or larger, and the Aeropack type adapter..

Wait, what? That's literally not possible; the centering rings don't fit the 29mm into the 38mm. They both have OD and ID that fit them from their MMT size to the 54mm size, only.

New England?! where abouts?

North-western Connecticut.

 

[jd2cylman]

Not my quote, but if you use Aeropack adapters, they nest. So to adapt down to 29 from 54, you have to use the 29/38 adapter and the 38/54 adapter together. But since they’re aluminum, it should be ok.
The LOC adapters are all to the 54 size in one step.