Falcon Heavy Build 2.0

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Two years ago I built a 1:90 scale Falcon Heavy model using the Falcon 9 kit from SpaceX and the 3D printed Falcon Heavy parts from Boyce Aerospace that were available at that time.

Since then, I got a 3D printer and started designing and building scale model rockets from scratch. First, I built a two stage Falcon 9 and then, a two stage, three cluster Delta IV Heavy. But those projects were always intended as learning exercises. So that one day I could return to the Falcon Heavy and build version 2.0.

So here’s my latest build: A 1:90 scale model of the Falcon Heavy that SpaceX launched on Feb 6th 2018. You can view the SpaceX Falcon Heavy launch here.




As with my previous builds, the goals of this project are ambitious:

1: A working three cluster, two stage model rocket of the Falcon Heavy test launch of the Tesla Roadster
2: 1:90th Scale* so BT-60 tubes can be used for the rocket body
3: Hidden “flip out” fins for the second stage based on Tim's design at Apogee Rockets
4: Working landing legs that extend for (an attempt at) upright booster recovery
5: Pneumatic/magnetic booster separation from the core at BECO
6: Movable grid fins
7: Retracting thrust struts on the core after booster separation
8: Payload: Red Tesla Roadster with Starman
9: No glue, so parts can be replaced as needed.

The two stage ignition will work like my previous Falcon Heavy where a BT-20 or BT-50 motor tube carries the ejection charge to ignite the second stage motor.
I plan to use the same rear ejection technique as I have used before.
Rear ejection will also trigger deployment of the landing legs as on my Falcon 9.
The landing legs on the core, will also serve as fin mounts to aid stability after the booster separation.
The 3D printing will be done on a Prusa i3 MK3s 3D printer and all of the designs will be created using FreeCAD software.

Here’s how booster separation & recovery worked on my first Falcon Heavy. The current design differs only slightly.




Here are most of the parts.


Here are the flip out fins on the 2nd stage:


Here's the retractable thrust struts:




The thrust struts are hinged on eyeglass screws and a small dental rubber band is used to retract the thrust struts.



The fins on the core are integrated into the landing legs: The LOX and LH2 fuel lines are printed on adhesive paper. The adhesive paper is removable. This is a model detail I'm still not happy with and is a work in progress. The 3D printed LOX and LH2 fuel lines are incredibly hideous without the adhesive paper detail.
You can also see slots for rubber bands in the landing legs which I've decided to abandon. Also note the use of steel screw eyelets for the landing leg hinges. I discovered the 3D printed hinges were not reliable on my F9 build.



Here's a test piece showing the eyelets at the end of the landing legs & eyeglass screws that secure them.




Here's a view of the core from the bottom. You can see the how the fins extend from the landing legs. You can also see a booster attachment magnet extending outward between the landing leg mounts.. I have a separate core motor that can accommodate D and E motors.



This shows how the legs extend and fold the fins down during recovery:



The grid fins extend:


And the landing legs extend for landing. Here's a close up of the extended landing legs showing the telescoping aluminum tubes.


You can see the magnet in the tip of the landing leg that is held in place by a magnet on the motor mount that gets ejected during recovery.

This figure shows the position of magnets that hold the landing legs in place (green). The entire motor mount gets ejected during recovery which releases the landing legs.



Here's the Falcon Heavy version 1.0 vs version 2.0



I still have a lot of work to do. But I've made enough progress that I thought I'd post what I have so far. This is really a beta version. So many new ideas have been introduced: the bug list is a mile long. I've already started on the design and build of 2.1.

Hopefully, I'll get a chance to fly this bird in November...

 

[les]

WOW! Looks Fantastic. Some clever engineering there. Can't wait to see launch video!

 

[neil_w]

Wow indeed.

 

[Switch]

So last week was a 4X exercise in failure. The Falcon Heavy II suffered the most of all. With only the center core infighting (despite multiple continuity checks). The boosters separated due to the launch force of the core. So here it is for entertainment value only:



And so it goes, repair the broken parts and plan for the next launch window....

 

[gerbs4me]

the model looks great! too bad for the damage during launch though. Hope its repairable so it can fly again.

 

[Switch]

Today I got another chance to fly the Falcon Heavy. Unfortunately, this time the boosters ignited but not the core.



Here you can see that the core is not burning & the lower right booster mount has failed.


Here you can see that the magnetic sheer pins that hold the core motor in place have failed and the core motor has been ejected passively.

The reason the core did not ignite is because I had loaded a spent motor by mistake. On the positive side, nothing was damaged and ejection of the booster motors worked.