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Tyler P

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I'd just get a new stiffy coupler and rebuild the top section with some fresh pieces. Really too bad when that happens. I see why guys use plastic rivets on the big stuff.
 

jd2cylman

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I told him we should make Goblin Saucers... Mine broke off right above the fin unit after a failed deploy.
Yes I saved the fin unit. No I haven't figured out how to make the saucery part to cover the fins yet...
 

Tyler P

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In all honesty, a little elbow grease and a palm sander and you should be able just to clean up the whole motor-mount/fin can assembly and slide it into a new tube. Have a new rocket to fly in a couple of hours, lol.

Love the saucer idea, too! That would be awesome.
 

Tobor

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On the subject of drag separation - I suffered a catastrophic separation at Midwest Power. My first flight was on a J275 and it was picture perfect. So, naturally I had to try a K185 long burn :) Well, about 2 seconds into an 8 second burn the nosecone popped off and the rocket shredded. It seems odd to me that I’d suffer a separation on my second flight and at much lower altitude and speed than the J275, but that’s my best guess as to what happened. At any rate, here’s my before and after photos for your viewing pleasure(?).

View attachment 437499

View attachment 437498

The good news is the fin can is completely solid still and I can probably do something with it - still have to figure out what exactly. Any ideas?

And a replacement Goblin is on order already 😁

~Dave~
Yeah, I saw that happen. It was painful to witness.
As to it's next life, maybe use it as a booster? Two stage Goblin for twice the fun... :p
 

Joshua F Thomas

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Has anyone used sheer pins to hold the nosecone on? Or are you all just using regular friction fit?
 

rfjustin

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On the subject of drag separation - I suffered a catastrophic separation at Midwest Power. My first flight was on a J275 and it was picture perfect. So, naturally I had to try a K185 long burn :) Well, about 2 seconds into an 8 second burn the nosecone popped off and the rocket shredded. It seems odd to me that I’d suffer a separation on my second flight and at much lower altitude and speed than the J275, but that’s my best guess as to what happened. At any rate, here’s my before and after photos for your viewing pleasure(?).

View attachment 437499

View attachment 437498

The good news is the fin can is completely solid still and I can probably do something with it - still have to figure out what exactly. Any ideas?

And a replacement Goblin is on order already 😁

~Dave~
What size vent hole did you have in the bottome/booster?
 

gtg738w

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Friction fit will be fine at lower altitudes. I would not recommend shear pins unless you plan to ground test.
Russ
 

ChicagoDave

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What size vent hole did you have in the bottome/booster?
I believe I had just one 5/32" vent hole, about 1" below the shoulder of the nosecone.

My working hypothesis is that the longer casing for the K185 (54-1706) caused me to place the nomex against the vent hole. I wasn't using shear pins, so it's always possible the nosecone fitting was somehow different between the two flights. I tested the friction fitting before the flight and it was "lift the rocket" tight. I doubt I'll ever know for sure. At least the fin can is still in good shape :)
 

Steven88

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I had my eyes on the 4” goblin for a while, but with little time to build and keep wife happy, decided to go with a pre built FiberMax for now.
 
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