Here's my newly finished GOBLIN and an engine question.

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Vigilante_A-20_DEMON

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I just fished putting the clear coat on my GOBLIN today. Since it's top heavy and the engine hook sticks out past the fins, i made a custom stand out of a scrap piece of particle board and broom stick. I have a question about engines. The GOBLIN engine mount is sized to accept " D " engines. The kit says this will fly with " C " engines also. How can you use C engines? how will they stay in? they just fall out. The D engines are about 15/16 diam and DSCF0358.jpg the C's are about 11/16 diam??
 
Use something like this:

https://www.hobbylinc.com/estes-sta...pFsaI960cWkx4TrO1dZ4JkvrRxpv_XJWNoaAiBt8P8HAQ

It's possible to build your own adapters much cheaper using an expended D motor casing and cutting it into adapter sections. As long as the nose end and the tail end of the live motor fit inside the motor hook and the adapter rings are fit firmly with masking tape, they will work fine.

The super quick-and-dirty way to turn an expended D into an adapter is simply to knock out the ceramic nozzle and peel away the innermost charred layer of the paper casing. Then just slide in the 18mm motor -- but be sure to secure it with a layer of tape.

Also, the C11 motor is 24mm diameter anyway and will fit in D-motor mounts.
 
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Motor mount adapter. Either commercial made or homemade. You'll be looking (from my understanding of your post) for a 24 to 18mm adapter. I normally just use a spent motor casing of the larger size that I've drilled the nozzle out of. Not pretty, but it's free and it works.
 
Yeah, one problem with converting a spent casing to an adapter is that fairly often the process of knocking out the ceramic nozzle bends the paper casing out of round. So you have to be patient, use medium force, and try to 'chip' it out of there rather than blasting it out with one big hammer swing.
 
Here's mine:

I'm not sure if it's for a "normal" 24mm or one of the "long" engines. Can you tell what it's made from?

18mm adapter.JPG
 
Just checked the recommended motor sizes on Estes' website. The Goblin can fly with the C11-3 and the C11-5 motors.

Those motors are standard length (2.75"), 24mm diameter motors (the same as the Estes D motors). No adapter needed to fly them.
 
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JStarStar said:
Yeah, one problem with converting a spent casing to an adapter is that fairly often the process of knocking out the ceramic nozzle bends the paper casing out of round. So you have to be patient, use medium force, and try to 'chip' it out of there rather than blasting it out with one big hammer swing.
Click to expand...

OP, please ignore my original response. It's not in the best interest of the hobby, and will likely cause significant bodily injury or death if you attempt the free adaptation of rocketry detritus for further use. Commercial versions of the free alternative I suggested are available from most hobby rocketry suppliers, and are encouraged due to the well-known correlation between money spent and likelihood to survive a model rocket launch.
 
Thanks for the replies so far. It's good to know you can fly this rocket with smaller motors like the C motors. I heard this rocket is kind of famous for getting lost since it is a fairly small rocket and can use higher powered engines unless you are out on a very large field with little or no trees which would be even better. I wish i lived in the wide open U.S. MID WEST, WESTERN states where there's a lot of desert and huge dry lake beds, that would be the ultimate! When i started rocketry in the 80's, the largest engines i used were the C engines, C6-5's. Now i'm just getting back into it and looking forward to using the larger D engines which will be a new experience for me. But hey, losing Rockets is PART of the hobby!!
 
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Vigilante_A-20_DEMON said:
Thanks for the replies so far. It's good to know you can fly this rocket with smaller motors like the C motors. I heard this rocket is kind of famous for getting lost since it is a fairly small rocket and can use higher powered engines unless you are out on a very large field with little or no trees which would be even better. I wish i lived in the wide open U.S. MID WEST, WESTERN states where there's a lot of desert and huge dry lake beds, that would be the ultimate! When i started rocketry in the 80's, the largest engines i used were the C engines, C6-5's. Now i'm just getting back into it and looking forward to using the larger D engines which will be a new experience for me. But hey, losing Rockets is PART of the hobby!!
Click to expand...

Not once you start building $300 - $500 HPR kits! :wink:
 
For many years I flew my Goblins only on D12-5 or -7's. It's a fantastic flying machine on those engines. Most of the time the model came down within our 80acre flying field (as long as the breeze was reasonable).
On days that the breeze became windy in the 15-20mph range, Switching to a C6-5 was the best way to ensure the model came back for another flight.

Making up 24 to 18mm adapter's are a snap. All that's needed is a 3" piece of BT-20 motor tube, a standard motor hook, and 2 or 3 AR-2050 centering rings.
These adapters are a lot lighter then using a spent motor casing and have positive motor retaining. Once you have a couple of these made up they last years.
It's also possible to do much the same thing with a 2" piece of BT-5 and a few AR-5-20 centering rings to allow flying standard 18mm motor models with 13mm motors.

24mm to 18mm motor adapters-sm_3-ring_02-10-90.JPG
 
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Bat-mite said:
Not once you start building $300 - $500 HPR kits! :wink:
Click to expand...

True, but for ME, and i'm sure this applies to MANY others in this hobby, it's not just the money, it's the time and effort put into building them and their classic status in some cases also, which is priceless IMO whether the rocket is a $20 rocket or a $500+ rocket:wink: For instance I have 3 classic rockets, Vigilante, Canaroc Eliminator and A-20 Demon that i built in the early 80's that would hurt me more 10 fold if i lost them than if i lost ANY expensive rocket costing 10-20 x more. Value isn't always in $$ for some.
 
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Vigilante_A-20_DEMON said:
True, but for ME, and i'm sure this applies to MANY others in this hobby, it's not just the money, it's the time and effort put into building them and their classic status in some cases also, which is priceless IMO whether the rocket is a $20 rocket or a $500+ rocket:wink: For instance I have 3 classic rockets, Vigilante, Canaroc Eliminator and A-20 Demon that i built in the early 80's that would hurt me more 10 fold if i lost them than if i lost ANY expensive rocket costing 10-20 x more.
Click to expand...

Good answer!
 
I was just responding to your comment, "But hey, losing Rockets is PART of the hobby!!" I can't afford for it to be a part of my hobby!
 
Bat-mite said:
I was just responding to your comment, "But hey, losing Rockets is PART of the hobby!!" I can't afford for it to be a part of my hobby!

Oh, okay, fair enough and also valid too! Either one accepts it or moves down a couple notches to cheaper rockets OR pick up a hobby that incurs NO LOSSES. if that's the case. I know what you responded to. " I " posted " But hey, losing rockets is part of the hobby!! "And YOU responded with (in your original 1st response) "NOT" once you start building $300 -$500 HPR kits" Which implied that losing rockets only hurts or counts as a LOSS when you lose expensive rockets which is simply NOT true for a lot of other Rocketeers. :rolleyes: NOT SAYING ANYTHING NEW, all rockets have and can be lost or damaged, plain fact that everyone knows. Like i said it's part of the hobby, it sucks for a little while and you just move on, build another one, repair or replace. When i 1st started this hobby back in 1980-81 and lost my 1st rocket which was the DER RED MAX that came with the BIGFOOT launcher combo kit, AND i thought to myself that "i will no longer do this because you LOSE rockets", which is simply an unrealistic view. Thus my conclusion that "losing Rockets is part of the hobby", cheap rocket, but sucked just the same, no matter the price.
Click to expand...
 
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Vigilante_A-20_DEMON said:
True, but for ME, and i'm sure this applies to MANY others in this hobby, it's not just the money, it's the time and effort put into building them and their classic status in some cases also, which is priceless IMO whether the rocket is a $20 rocket or a $500+ rocket:wink: For instance I have 3 classic rockets, Vigilante, Canaroc Eliminator and A-20 Demon that i built in the early 80's that would hurt me more 10 fold if i lost them than if i lost ANY expensive rocket costing 10-20 x more. Value isn't always in $$ for some.
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Absolutely Vigilante!
Great Answer! Like you I have models built back in the 80's, that are much more important to me than any HPR 3F&NC of any price.
Sometimes it's the memories that are all important.
 
I have a video on YT of one going up on a C6-5. Even that engine sent it up pretty far - a D would really make it go.
 
My Semroc GOBLIN came with a separate motor adapter that I had to assemble and use to fly a C6-5.... but I've since learned there are D and E sized C-motors available!
 
Kirk G said:
My Semroc GOBLIN came with a separate motor adapter that I had to assemble and use to fly a C6-5.... but I've since learned there are D and E sized C-motors available!
Click to expand...

I'm in the same boat, i too did not realize there are D and E sized C motors!
 
The C11-5 is a great alternative to the D12-7, with about half the altitude, no adapter needed. I've flown both these motors in my Goblin(s) many times.
 
I think a Goblin can even fly on a B6-2 or B4-2, if you want to send it low and slow, if you haven't really overbuilt it with superthick fillets, multiple paint coats, etc etc.

It'll only clear 100' or so but if you're on a small ball-diamond sized field, that might be the ticket.
 
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You mentioned that it is too heavy, but I didn't see if you posted what the weight was. How much does it weigh (including recovery) without the motor?

Greg
 
GregGleason said:
You mentioned that it is too heavy, but I didn't see if you posted what the weight was. How much does it weigh (including recovery) without the motor?

Greg
Click to expand...

Greg:
My original Goblin with streamer but no motor was 54.9g, My rebuild using most of the original parts and adding an 24 to 18mm adapter weighs in at 62.6g without motor.
 
I just discovered my twice flown Goblin (on a C6-3 and then a D12-5) has an "Estes smile" in the black balsa nosecone. Unfortunately, the smille also seems to have cut across the grain, and so a good little "chip" has been lost to the rocket gods...

The only repair that I can think of is to fashion some wood filler into the missing smile and sand it down until almost smooth with the rest of the cone. I still have lots of black gloss paint, so covering and repainting the nosecone is not a problem.

Anyone else got any suggestions on how to avoid this problem again?
 
Kirk G said:
I just discovered my twice flown Goblin (on a C6-3 and then a D12-5) has an "Estes smile" in the black balsa nosecone...

Anyone else got any suggestions on how to avoid this problem again?
Click to expand...

If you have an elastic or rubber recovery harness, replace a substantial length with a longer length of Kevlar or similar material.

Greg
 
Kirk G said:
I just discovered my twice flown Goblin (on a C6-3 and then a D12-5) has an "Estes smile" in the black balsa nosecone. Unfortunately, the smille also seems to have cut across the grain, and so a good little "chip" has been lost to the rocket gods...

The only repair that I can think of is to fashion some wood filler into the missing smile and sand it down until almost smooth with the rest of the cone. I still have lots of black gloss paint, so covering and repainting the nosecone is not a problem.

Anyone else got any suggestions on how to avoid this problem again?
Click to expand...

I've experienced the same thing with my Goblin; and adding a longer rubber or elastic shock cord is not as effective as Greg's suggestion. My guess is the relative mass of the cone and the airframe , combined with the um... energetic ejection charge results in a lot of recoil force. Adding an additional length of inelastic material like kevlar is the way to go. I think my current elastic and kevlar combo cord is almost 4x the length of that model.
 
Your Goblin turned out great - can't go wrong with black & yellow paint scheme!
 
GregGleason said:
If you have an elastic or rubber recovery harness, replace a substantial length with a longer length of Kevlar or similar material.

Greg
Click to expand...

OK, so where doth one find this legendary substance you refer to as "Kevlar" cord? In quantity or in cut lengths?
 

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