8" Goblin with 4 x 75mm Cluster

[mtnmanak]

I finally got around to finishing a build thread for this rocket.

It is a @WILDMANRS 8" Goblin with carbon fiber honeycomb fins and a 4 x 75mm motor mount.

I don't think this will be the final paint job. I used a metallic Duplicolor paint that has proven to be fragile and blotchy. But, I am tired of painting this thing now, so I am going to leave it as is until I find the time to sand it all down and start over.

Build thread:

https://www.mountainmanrockets.com/index.php/builds/8in-goblin-with-4-x-75mm-cluster/

 

[DeeRoc29]

Looks nice, good work. Orange Metalcast is one of my favorite colors for rockets. Lots of very light coats is the key to even finishes. Harder to do on large rockets, for sure.

 

[mtnmanak]

Looks nice, good work. Orange Metalcast is one of my favorite colors for rockets. Lots of very light coats is the key to even finishes. Harder to do on large rockets, for sure.

Unfortunately, I didn't do a great job with the base coat, so it is already flaking off in places. I have no doubt that a high thrust flight will result in a spectacular shower of Metalcast paint chips

 

[DeeRoc29]

I forgot to mention that I prefer not to use the Metalcast base coat. I've found that Duplicolor aluminum engine enamel results in a better finish not just for the orange but all of the Metalcast colors.

The green is really sweet, too.

 

[mtnmanak]

I forgot to mention that I prefer not to use the Metalcast base coat. I've found that Duplicolor aluminum engine enamel results in a better finish not just for the orange but all of the Metalcast colors.

The green is really sweet, too.

I have a whole bunch of the aluminum engine enamel and I have a number of cans of the metalcast purple. I have a 9" Mega Buster build just getting under way, sounds like a chance to try out your suggestion!

 

[Theory]

great tip!

im going to shoot some metal cast purple on my next build. will definitely check out the aluminum engine enamel

 

[David_Stack]

I had assumed the Metalcast was lacquer, like the majority of the Dupli-Color line. Isn't lacquer over enamel a recipe for trouble? Maybe the Metalcast paint is enamel as well?

Seems to be working for DeeRoc29 tho'.

 

[mtnmanak]

I had assumed the Metalcast was lacquer, like the majority of the Dupli-Color line. Isn't lacquer over enamel a recipe for trouble? Maybe the Metalcast paint is enamel as well?

Seems to be working for DeeRoc29 tho'.

According to Duplicolor, Metalcast is enamel:

https://www.duplicolor.com/product/metalcast-anodized-automotive-paint/

 

[Woody's Workshop]

I'm extremely curious (I've never bothered to price such big engines).
If you fill the EM's for maximum altitude, what's that thing going to cost per flight?
You must have a whole lot more money to burn than I.
I bet flying that thing once is about equal to what I have to spend in 10 years.

 

[OzHybrid]

Remember that metallic flake and aluminium finish paints can seriously affect your radio signal range from your electronics.

 

[mtnmanak]

Remember that metallic flake and aluminium finish paints can seriously affect your radio signal range from your electronics.

Excellent point! Usually, my RF electronics are in the nosecone, as is the case in this rocket, and I try to avoid metallic paints for that portion of the rocket. In this case, the nosecone got a nice coat of enamel.

 

[mtnmanak]

This 8" Goblin has gotten a lot of use throughout the past couple years. Last year, at URRF, she flew on 4 x L1170FJ motors. This year, after a much needed fin repair and a new coat of paint/decals, she is flying at LDRS on 2 x K1499s airstarting to 2 x M2050Xs.

 

[ljwilley]

Awesome! When it flies, please post a video!

 

[mtnmanak]

Video of the actual flights has been a bit of a problem. The rules regarding these large, complex cluster launches have forced the pads further and further away. This has made it more difficult to get video of the flight. The video I took last year at URRF was from almost a half mile away. Suffice to say, with the video equipment I have, the video was exactly how you would expect it to look - so far away, all you could see was the smoke trail - you could barely make out the rocket.

Note, this is not a comment about the rules, but on me needing better video equipment

 

[ljwilley]

I would still like to see one...

 

[mtnmanak]

Let me see what I have for footage and see if I can cobble a bit of a montage.

Definitely hoping to get some better video this year!

 

[mtnmanak]

Here is a cool photo of the launch on the 4 x L1170FJ motors last year:

View attachment 1U3A0080.JPG

 

[Hobie1dog]

When you do something it's BIG I don't understand why a rocket has to be 1/2 mile away

 

[mtnmanak]

When you do something it's BIG I don't understand why a rocket has to be 1/2 mile away

Technically, as per Tripoli safety code, this rocket only needs to be 1500 feet away from the flight line (well, again, technically, 1500 feet away from the flight line and any inhabitable structures, but that is not an issue at URRG) on a complex N flight, but a complex P launch bumps the distance up to 2500 feet and, since there were complex P flights planned at that launch, that was the distance of the way-away cell. So, not quite a half-mile - call it 0.47 mile .