Luna Bug Upscale BT80 Build

[Back_at_it]

Been messing around with the new laser for a couple of weeks now and decided it was time to build something I've been kicking around for a while. A couple of years back I built a BT60 upscale of the Luna Bug and have been wanting to do a BT80 ever since but wasn't looking forward to cutting the fins. Since buying the laser, I figure I am out of excuses so lets get started.

- BT80 Body tube. Slightly stretched over stock. This one is 13 inches.
- Estes BT80 NC80B "Bertha" nose cone.
- 29mm motor mount. 5 inches long.
- Rocketry Works upper centering ring.
- Light weight rear ring.
- Fins cut from 3mm ply. Added a couple of extra holes in the fins to make the design a little more interesting.
- Landing pads cut from 3mm ply.
- Not Shown. I'll be using 500# Kevlar for the recovery along with a 1/4" launch lug.



Starting with the motor mount. This rocket is going to come in somewhere around the 9oz mark when completed so I plan to fly it on Estes 29mm motors. To begin I'm inserting a motor block. The outside to the motor black has been sanded to open up the fibers.



Next up was the upper centering ring. I was going to cut my own upper ring for this but I have a dozen of these Rocketry Works rings on the shelf so I decided to use it. The outer layer was peeled from the motor tube where the centering rings will attach.



Next up was the adding the Kevlar for the recovery system. For this I'm using 12ft of 500# Kevlar from Emma's kites. I punched out the opening in the upper rings and threaded the Kevlar through them then tied it off. Glue was also spread into the unused slots for strength.

At this point I also peeled off the remaining outer layer of the motor tube. I don't know why I didn't do this originally





A piece of heat shrink was added to the shock cord for protection and fillets were done to top and underside of the centering ring.



Last thing I did for the night was cut the slots in the body tube for the fin tabs then glue the motor mount into the body tube.




Next up will be attaching the fins. Should hopefully get to that before the weekend.

 

[Back_at_it]

Installed all three fins over the past couple of days. I first removed a section of the outer layer of the tube where the fins will attach.

I decided to use epoxy to attach these fins. They are large and I figure they could use all the help they can get on landing. While I plan to fly this mostly on 29mm E and F motors, there's always the chance that a composite could find it's way in there. I felt the epoxy soaking into the tube around the attachment points will help with rigidity and strength.

First fin attached.



Second fin attached.



Third fin attached and I couldn't help but still the nose cone on for a peek at the semi finished rocket.



While the fins were drying, I assembled the landing pads. When I built my BT60 Luna Bug, the biggest issue I had on landing was snapping off the landing pads. No amount of glue would keep them on until I added some reinforcements to the top. Once added the issues stopped. I decided to add them right off the bat on this build.



This weekend will be internal and external fillets and adding the launch lugs. Should have the construction finished in a couple of days.

 

[Back_at_it]

Over the weekend I managed to get the Luna Bug to a point where it is ready for primer.

I first added the Internal and external fillets. Used epoxy for both.



Add my custom light weight rear centering ring. For something this big and draggy it makes no difference but It gave me an excuse to play with the laser.



Added the Rocketry Works motor retainer using epoxy.



Attached the landing pads.



Finally attached some 1/4" lugs.



At this point the assembly is complete with the exception of connecting the nose cone but that will happen after paint and vinyl. Now I just need to decide how I want to paint this.

 

[dhbarr]

Is your top ring on the motor tube a solid one? If it's open as with the aft centering ring, I'd think the ejection charge wouldn't pop the nose.

EDIT: Disregard, I see it up there.

 

[Back_at_it]

Primer finally happened. Two coats of SEM high build. Still need to do a final sanding before paint.

Now comes the hard part. How to paint this. Completely open to ideas.

 

[PDawg]

Bright Green, black Nosecone and landing pads.

 

[ThirstyBarbarian]

It looks very cool! I would probably go for a “goofy NASA” look. Kind of similar to a Mars Lander — mostly white, red legs, maybe a roll pattern and NASA logos or a flag. Maybe a hatch, windows, portholes, etc.

 

[billpr]

Looks great. Maybe a Space X look, with logos from different companies.

 

[goose_in_co]

Steampunk!!!!

 

[Cape Byron]

Cool aft CR. I like the hexagonal lightening holes.

 

[billpr]

Maybe a Mars Lander look.

 

[BABAR]

somehow I keep seeing this:

 

[John Kemker]

somehow I keep seeing this:

View attachment 640640

 

[Back_at_it]

Back with an update finally. After racking my brain I decided I wanted to go with a metallic machinery look on for the paint job. I got the first coat of Krylon copper metallic applied and had to let the project sit for a while. In the meantime, the club launch came up so I figured I'd attach the shock cord and give the rocket its shakedown flight.

First flight on a E12-4. The field was huge and I was worried about the landing pads so I went large with a 30" chute. Flight was perfect but the landing not so much.



After getting the rocket home I found a crack in the fin that ran up to one of the holes. This exposed a weakness that I need to get fixed before this starts flying on larger motors.



After kicking around a dozen ideas from trying to paper the fins to completely ripping them off the rocket and going back with something thicker, I came up with the following. I designed and cut a couple of reinforcing plates from 2mm ply and cut them on the laser. While this will add weight, thickness and drag, it will also add a ton of style. The rocket has a 29mm mount so I can always use larger motors.




I sanded the paint and primer off the fin and attached the reinforcing plates using epoxy. Just need to cut 5 more and get them attached this week.

 

[PDawg]

External Braces, very cool!

 

[BABAR]

Loved the ending!

 

[Back_at_it]

Got a couple more of the braces installed last night. Going in a completely different direction with it now.

 

[Back_at_it]

After changing directions with the Bug, I decided to go full on Steam Punk. Never done one of these before but the style is fun and interesting.

I've added a number of details and I think it's coming along pretty well. Need a few more days to finish up the rivet details then it's time to figure out the paint.