Radical Rocketry F-104 Starfighter Build

[KenECoyote]

@BigMacDaddy has a 3D printed kit of the F-104 Starfighter available and this has been a favorite jet of mine since I first saw it, so I had to get one and I figured why not do another build thread?

Here's his thread on the kit (he also posts and sells them on Facebook):

F-104 Starfighter - Semi Scale (BT-60 + 3D printed Parts + Plywood Fins - BT-80 is next)

The last couple of weeks I have spent a good bit of time on the F-104 (for those that did not see this on FB). I started with a BT-80 version but quickly shifted down to a BT-60 version so I could more quickly protoype and test for stability. BT-60 prototype is ready to fly but some storms are...

www.rocketryforum.com

 

[KenECoyote]

His thread noted that the first version (currently available) is the BT60 one and while I asked to be put on the list for the BT80, I thought a smaller low power bird would be fun and would be a good first build before going bigger.

Plus I wanted to see how the kit is and how it comes together.

 

[KenECoyote]

As a side note it seems that BigMacDaddy is psychic because each time I think of some cool kit, suddenly he's testing it! lol

Before I saw his thread on the Starfighter, I had actually dug up my old Fat Cats F-104 and was going to start on that. The OOP Fat Cat one is a 3" diameter High Power kit with a 29mm motor mount, while the RR BT60 one here has a 18mm motor mount.

Note: I'll be editing as I recall things and adding pics as I dig them up.

 

[KenECoyote]

Of note is that there are three versions of the BT60 F104 kit available... regular (that most of us are familiar with), a stretched longer version and one of the NASA variant that had an extra booster on the tail - designed so you can install a 13mm mini motor and cluster it with the main motor.

I got the regular one.

Here are the kit pieces...


What's cool is that the wingtip tanks are included. I had thought of adding similar to the Fat Cat kit myself since some of the F104 versions I was thinking of building looked better with them.

Disclaimer: Please don't use this as a replacement for the original instructions; this is just my experiences which may be out of order!

 

[KenECoyote]

I was very impressed with the print quality! I initially had some doubts since I have seen 3D parts in other kits (as well as my 3D printings) and they usually aren't that high resolution and require a lot of filling and sanding.

I thought for a small scale kit, it was pretty darn amazing! Don't get me wrong... it still requires some sanding and a bit of filling if you want a really nice looking rocket, but to be honest it is a fantastic looking rocket even if you don't.

Here's an example... the canopy was my biggest point of concern since it's supposed to represent smooth glass, so if you have 3D layer ridges, it might be very noticeable. For the canopy, I only did some light sanding with a small hand detail sander, primed with Rustoleum Filler Primer, did another very light sand and here are the results:




Still need further cleanup and touch-up, but close to final:

Now I'm super happy with the printing because if it was poor, sanding it smooth would basically wipe away the details like the canopy frame.

 

[KenECoyote]

As you probably surmised by now, I'm pretty far along the build already. I was holding off on posting a new thread because I wasn't sure how this kit would turn out and how it would fly as a rocket, but at this point it's passed every test and I'm far enough along.

Let's just hope I remember everything.

So BigMacDaddy has instructions to download from his website:

https://radicalrocketry.com/contact-us

In the directions, it gives a lot of helpful pointers about 3D print handling, cleanup, filling and gluing.

 

[KenECoyote]

Here's one of the fun parts... removing the brim off of the printed parts! When it's high resolution, it easily comes out.


I've had some prints including my own that required an Xacto knife to remove the brim, but not in this case.

It's also noted to keep these brim pieces so that you can create "ABS juice" for filling or gluing (very helpful info!). I kept the pieces, but didn't get around to picking up acetone for it and it's winter here in NY, so I didn't want to work with that indoors.

 

[KenECoyote]

Time for an eye candy break!

One of the coolest things about the F-104 Starfighter as a rocket kit is the astonishing number of paint schemes you can find on them!

One of my hardest decisions was how to paint the rocket. Heck, I've had the Fat Cat kit for years and I still haven't decided!

Here are some that I plan to or would like to do eventually:







Here's one that would be quite a challenge!

 

[hobie1dog]

thanks for all the pictures.

 

[KenECoyote]

I've a ton to write, but will have to do it in parts, so please bear with me!

 

[KenECoyote]

As I was removing the brims, I inspected each piece and planned to trim and sand as I wanted.

The only noticeable imperfection was to one of the intake cones, which wasn't any real issue and some trimming with an Xacto followed with light sanding fixed it right up.

BigMacDaddy also had instructions on sanding the parts such as the nose cone; noting that sanding against the grain, it will sound "like a DJ scratching a record" (it does! Lol)

I stuck the tail cone into a spare section of BT-60 as a holder while I sanded it to my liking.

Pretty easy peasy.

 

[KenECoyote]

The wings and tail feathers are CNCd out of thin plywood and so the nubs need to be trimmed.

 

[KenECoyote]

Now comes cutting the BT-60 to the proper length (and the BT5 if you want wing tip tanks).

I used the Estes tube cutting guides here.


I'll add again that I really love the inclusion of the wing tanks... it's a small detail that makes such a big difference if you wanted it. I was actually very eager to see how they looked!

 

[KenECoyote]

What I did next was tube marking followed by slot cutting since I wanted to see how this kit looks!

I made marks according to the directions.

For this kit, the nose cone had notches which you use to mark off the tube. Make sure it doesn't shift when you mark the second side.



I used an Estes tube marking guide here.

I also added a dotted line on the top using the rear of the canopy as a guide and this is for marking the lining up to the vertical stabilizer.

(The pic above shows my test fitting too.)

It's also useful to mark a single solid line on the bottom for the launch lug location.

With the slot cutting, be sure to use a fresh sharp blade, make multiple light cutting passes and leave the end cuts for last and you shouldn't have a problem.

 

[KenECoyote]

One unique part of this kit is that the side intake pods are actually used to help set the wings so that they are at a downward angle.

You're supposed to have the front of the intake cones aligned with the bottom line of the side wing slots.

(I didn't get a pic, but here is another that is close.)

 

[KenECoyote]

Regular assembly actually starts with the Motor Mount Tube in the aft section*.

A cool feature of this kit is that there are provisions for different motors.


(The longer white piece on the right is for the extended length version.)

*Note: I went a bit out of order here and after thinking about things, I first glued the vertical stabilizer into the slot in the boat tail. This is because I thought it would make sense to apply an internal fillet to the base. I used epoxy for the fillet.


I then used epoxy again to glue the motor tube into the boat tail**. I appreciated the extra handling time afforded since this part was a bit tricky for me.

**There was a note to add kevlar shock cord to the boat tail before gluing in the motor tube, but I forgot. So I simply drilled a small hole, knotted the end of the kevlar several times, glued the end, pressed through the hole, epoxied in place and did some test pulls. This worked fine for me, but YMMV.

 

[KenECoyote]

To be continued...

 

[KenECoyote]

On to the main body!

The inlet cones fit into the intakes lkke this...


...and then the wings go into the bt (with glue) and the intakes over them. I then applied CA all along the intake shrouds as well as where they meet the wings and kept them snug with rubber bands and clothes pins.


While the above was setting, I glued the horizontal stabilizer to the tail section and test fit it on the body.

 

[KenECoyote]

Wing pods added and now it's definitely looking like a jet!

 

[sambatterman]

Brilliant build!! Love this jet...

 

[KenECoyote]

One if my concerns launching this beautiful rocket was that the rear tail stabilizer section extends back and is made of thin plywood, so I thought that a traditional rocket landing may subject the section to breakage.

Given that, I set it up to cone down mostly flat with a slight tip upwards so that the plastic boat tail would hit the ground first.

I did this by drilling a small hole just behind where the vertical stabilizer starts (I had epoxied it in place and also applied CA to the area) and hooking a fish line system (made removable for testing as well as display):

The fish line is then attached to the kevlar line and parachute.

I planned for the nose (which is weighted) to have its own chute to limit the shock on the kevlar cord and fish line (plus have the body come down more slowly).

 

[KenECoyote]

thanks for all the pictures.

Brilliant build!! Love this jet...

Thanks guys! That feedback is very much appreciated!

 

[neil_w]

Zipper concerns?

 

[KenECoyote]

With the nose, weight needs to be added. An OR file is included, but a general guideline is 0.5oz if using 18mm motors and 1.0oz if using 24mm and check the CG! Rob also recommended a swing test.

Initially I planned on 24mm motors starting with a D12 because bigger is better, right?

So I added 1.0oz of some non-drying modeling clay inside the nose and it seemed kinda hefty lol. Good thing I was having it cone down on a separate chute.


However, I later decided to first try the 18mm with the new highly-touted and hyped C5-3, so I removed half of the clay (good thing it was non-drying).

I did this because it's winter here in NY, so my club isn't launching and the park by me isn't that large, so I wanted to keep the altitude appropriate for the park (plus winged rockets can weathercock significantly).

So I then removed half of the clay back to 0.5oz for 18mm motors and checked the CG.

 

[KenECoyote]

Zipper concerns?
View attachment 561808

Nah.

(Weighted nose cone is on a separate chute.)

 

[KenECoyote]

Swing test (with the C5-3 motor installed) was good!

(I probably looked like a kid swinging around a toy plane lol)

 

[KenECoyote]

So I purposely wanted to launch this before I put a ton of work into finishing it since it would be quite nervewracking not knowing how it flies and then very painful if it crashes into pretty little pieces.

Luckily the weather was looking pretty good for the next morning!

 

[KenECoyote]

Some interesting info for our interlude:

Lockheed F-104A Starfighter | Smithsonian Institution

www.si.edu

• "The missile with a man in it."
• "The first U.S. jet fighter in service to fly Mach 2."
• "The razor-sharp leading edge requires a specialty fitted cover when on the ground to protect the ground crew. A narrow fuselage fits tightly around."

 

[KenECoyote]

Morning of test launch!

 

[KenECoyote]

C5-3 is super!