Falcon 9 Crew Dragon Build 2.0 (1:65 Scale BT-70)

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Here is my latest build of the Space X Crew Dragon that flew Bob Behnken and Doug Hurley to the International Space Station (ISS) on May 30, 2020. This was the first launch of United States astronauts to the ISS from a US launch vehicle since the Space Shuttle program was retired 11 years ago. You can view the historic SpaceX launch here:


As with my previous builds, the goals of this project are ambitious:
  1. A 9 cluster, two stage model of the Falcon 9 Crew Dragon
    1. The 9 cluster 1st stage uses a relay box which you can check out here
    2. I plan to use the same rear ejection technique for first stage recovery and second stage ignition as I have used before
  2. Working landing legs that extend for (an attempt at) upright recovery of the 1st stage
    1. This is triggered by rear ejection as on my previous Falcon9.
  3. Printable “skins” for added scale rocket detail
    1. On my most recent Falcon Heavy project, a significant amount of effort was spent on painting and wet sanding. This project uses printed paper “skins” instead of painted parts
    2. The skins are adapted from AMX Paper Scale Models.
  4. Snap-in parts and add-on parts to integrate with the “skins” for the finished project
    1. To simplify the application of printable skins, parts that extend from the rocket body tube are printed separately and snap into holes that are pre cut into the body tube parts.
  5. No glue™, so parts can be replaced as needed
    1. Tube parts are fabricated to fit together using friction or, as mentioned below, parts are designed to snap into place. Also as mentioned below, paper adhesive “skins” are used to wrap the body tube parts to hold them together
    2. OK, I'm still using glue in a few places.
  6. Hidden “flip out” fins for the second stage based on Tim's design at Apogee Rockets
  7. Magnetic shear pins for core motor retention, landing leg release, and capsule retention/release
  8. Movable grid fins
  9. Separate recovery of the Crew Dragon capsule
  10. 1:65 scale so BT-70 tubes can be used for the rocket body.
    1. My first Falcon 9 Dragon was done with BT-60 tubes at 1:90 scale, too small or more than one modle rocket motor.
    2. BT-70 tubes allow for a 9 cluster model Falcon 9 rocket
    3. So this scale makes a 3 core, 27 cluster model Falcon Heavy possible.
The 3D printing was done on a Prusa i3 MK3s 3D printer and all of the designs were created using FreeCAD software.

Here's the finished build (Height: 102 cm/ 40"):
IMG_1398.JPG



The rocket has nine engines (just like the real Falcon 9):
IMG_1402.JPG

That's 8 A10-OT engines surrounding a center E12-0.

Here's the CAD drawing of the motor mount:
9_cluster_motor_mount(2).PNG

Here is more information about my attempts to do a 9 cluster rocket.

The fins are integrated into the landing legs:
IMG_1399.JPG


The landing legs flip out when the 1st stage motor ejects during reverse recovery. Here you can see the magnetic sheer pins at end of the landing legs. In the upright position, each magnet is paired with a magnet in the motor core, so when the core ejects, the legs are released. This also holds the core motor in place prior to launch.
When the motor core is ejected, the recovery chute deploys and it is attached to the top of the 1st stage for (an attempt at) upright landing:
IMG_1400(1).JPG

In my previous 1:90 scale Falcon 9, I had to use aluminum tubes for the landing leg supports. Here, the telescoping tubes are 3D printed, which greatly simplified the work for the landing legs.

The grid fins extend (but are not activated during landing - coming soon!):
IMG_1404.JPG




Note: this is the part of this build that is totally new!

Instead of printing the top of the 1st stage with grid fin mounts, LOX & LH2 Fuel lines as one piece, each part is printed separately. The top of the 1st stage has holes for the grid fin mounts, and LOX & LH2 Fuel lines (plus hidden round holes hidden by the grid finds for the ejection exhaust). The grid fin mounts, and LOX & LH2 Fuel lines are printed with tabs that fit into these holes. The AMX paper rocket skins are applied over this 3D printed part and the adjoining BT-70 tube and also cover these holes. This makes application of the skins very simple since there are no parts protruding from the 3D printed tube. The skins also function as the "glue" that holds the 3D printed parts to the BT-70 tubes. After the skins are applied, the holes need to be cut through the paper skin to allow the parts to snap into place.
BT-70_Falcon_9_Interstage_RTP(1).PNG


Here's the outside of the top LOX Line housing:
Falcon_9_3.0_LOX_top_part_RTP_front(1).PNG


On the inside you can see the tab that allows it to snap into the first stage section above:
Falcon_9_3.0_LOX_top_part_RTP_-_back(1).PNG


This is the grid fin mount that snaps into the square holes in the first stage shown above.
Grid_fin_mount_RTP(1).PNG


Here's the grid fin the snaps over the grid fin mount shown above:
Falcon_9_3.0_-_BT-70_Grid_fin_RTP.PNG


The second stage features flip out fins:
IMG_1403.JPG


The Crew Dragon capsule is recovered separately from the 2nd stage:
IMG_1405.JPG


It's held to the 2nd stage with small magnets:
IMG_1407.JPG


It can be opened for the astronauts or other payloads. Small magnets attach the two parts together.
IMG_E1412.JPG

crew_dragon_100621_capsule_RTP(1).png

crew_dragon_100621_Heat_Sheild_RTP(1).PNG

crew_dragon_100621_Magnet_ring_RTP(1).PNG

crew_dragon_100621_Trunk_RTP(1).PNG




Some parts, such as the camera on a lower section of the LOX fuel line are glued on to the outside of the paper skins:
LOX_2nd_section_RTP(1).PNG



And here is my 2nd failed launch attempt


That's 6 of the A10-OT engines igniting without the center E12-0 Engine and hence the belly flop. Note that the aerodynamics are sound as the rocket attempts to right itself as it falls...

That hard landing broke two of the landing legs, but more important was a fracture in the main engine assembly.

That's all fixed now and I'm looking forward to the next SARG launch event to see that happens next!
 
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Sandy H.

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Here is my latest build of the Space X Crew Dragon that flew Bob Behnken and Doug Hurley to the International Space Station (ISS) on May 30, 2020. This was the first launch of United States astronauts to the ISS from a US launch vehicle since the Space Shuttle program was retired 11 years ago. You can view the historic SpaceX launch here. My first Falcon 9 Dragon was done with BT-60 tubes at 1:90 scale.

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

  1. A 9 cluster, two stage model of the Falcon 9 Crew Dragon
    1. The 9 cluster engine uses a relay box which you can check out here
    2. I plan to use the same rear ejection technique for first stage recovery and second stage ignition as I have used before.
  2. Working landing legs that extend for (an attempt at) upright recovery of the 1st stage
    1. This is triggered by rear ejection as on my previous Falcon9.
  3. Printable “skins” for added scale rocket detail
    1. On my most recent Falcon Heavy project, a significant amount of effort was spent on painting and wet sanding. This project uses printed paper “skins” instead of painted parts
    2. The skins are adapted from AMX Paper Scale Models.
  4. Snap-in parts and add-on parts to integrate with the “skins” for the finished project
    1. To simplify the application of printable skins, parts that extend from the rocket body tube are printed separately and snap into holes that are pre cut into the body tube parts.
  5. No glue™, so parts can be replaced as needed
    1. Tube parts are fabricated to fit together using friction or, as mentioned below, parts are designed to snap into place. Also as mentioned below, paper adhesive “skins” are used to wrap the body tube parts to hold them together
    2. OK, I'm still using glue in a few places.
  6. Hidden “flip out” fins for the second stage based on Tim's design at Apogee Rockets
  7. Magnetic shear pins for core motor retention, landing leg release, and capsule retention/release
  8. Movable grid fins
  9. Separate recovery of the Crew Dragon capsule
  10. 1:65th Scale so BT-70 tubes can be used for the rocket body.

Here's the finished build (Height: 102 cm/ 40"):
IMG_1398.JPG



The rocket has nine engines (just like the real Falcon 9):
IMG_1402.JPG

Here's the CAD d drawing of the motor mount:
9_cluster_motor_mount(2).PNG

Here is more information about my attempts to do a 9 cluster rocket.

The fins are integrated into the landing legs:
IMG_1399.JPG


The landing legs flip out when the 1st stage motor ejects during reverse recovery. And the recovery chute is attached to the top of the 1st stage for (an attempt at) upright landing:
IMG_1400(1).JPG

In my previous 1:90 scale Falcon 9, I had to use aluminum tubes for the landing leg supports. Here, the telescoping tubes are 3D printed, which greatly simplified the work for the landing legs.

The grid fins extend (but are not activated during landing - coming soon!):
IMG_1404.JPG




Note: this is the part of this build that is totally new!

The top of the 1st stage has holes for the Grid Fin mounts, and LOX & LH2 Fuel lines (plus hidden round holes hidden by the grid finds for the ejection exhaust). The AMX paper rocket skins are applied over the tube and cover these holes. The skins also function as the "glue" that holds the 3D printed parts to the BT-70 tubes. After the skins are applied, the holes need to be cut through the paper skin to allow the parts to snap into place.
BT-70_Falcon_9_Interstage_RTP(1).PNG


Here's the outside of the top LOX Line housing:
Falcon_9_3.0_LOX_top_part_RTP_front(1).PNG


On the inside you can see the tab that allows it to snap into the first stage section above:
Falcon_9_3.0_LOX_top_part_RTP_-_back(1).PNG


This is the grid fin mount that snaps into the square holes in the first stage shown above.
Grid_fin_mount_RTP(1).PNG


Here's the grid fin the snaps over the grid fin mount shown above:
Falcon_9_3.0_-_BT-70_Grid_fin_RTP.PNG


The second stage features flip out fins:
IMG_1403.JPG


The Crew Dragon capsule is recovered separately from the 2nd stage:
IMG_1405.JPG


It's held to the 2nd stage with small magnets:
IMG_1407.JPG


It can be opened for the astronauts or other payloads. Small magnets attach the two parts together.
IMG_E1412.JPG

crew_dragon_100621_capsule_RTP(1).png

crew_dragon_100621_Heat_Sheild_RTP(1).PNG

crew_dragon_100621_Magnet_ring_RTP(1).PNG

crew_dragon_100621_Trunk_RTP(1).PNG




Some parts, such as the camera on a lower section of the LOX fuel line are glued on to the outside of the paper skins:
LOX_2nd_section_RTP(1).PNG



And here is my 2nd failed launch attempt


That's 6 of the A10-OT engines igniting without the center E12-0 Engines and hence the belly flop.

That hard landing broke two of the landing legs, but more important was a fracture in the main engine assembly.

That's all fixed now and I'm looking forward to the next SARG launch event to see that happens next.


Umm. Wow. I'm going to have to look for your previous build, as I don't recall seeing it and this one is amazing.

I hope your next launch is successful and you figure out how to get it signed by the astronauts, as your build is obviously showing great effort to model a pivotal experience in space travel and I bet they would like it.

Awesome!

Sandy.
 

manixFan

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Wow, very cool build! Lots of great synthesis getting it all to come together. I couldn’t watch the rest of the video, too painful to see such a neat model take a hard landing.

I hope you get a good way figured out on getting all the motors lit, it will be a show stopper for sure. Maybe a flash pan if you can protect the plastic parts.

Keep us posted!

Tony
 

Switch

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Well, here it is on the pad at Gibson Ranch Regional Park

IMG_1474a.jpg


The launch was a partial success: all 9 motors in the 1st stage ignited, the second stage motor ignited, 1st stage recovery worked, the capsule recovery worked, but the 2nd stage flip out fins and recovery failed.


The failure of the flip out fins was because the force of the 1st stage ejection charge pushed the motor assembly up into the 2nd stage body tube. I had this problem on my first Falcon 9 and thought I had resolved it by adding a ring that was the outside diameter of the body tube. But in this case, I had already printed and assembled the 2nd stage motor & flip out fin assembly, so the ring was printed and glued on separately. Well, the glue failed. Fortunately, I only need to reprint that one part, and it will be ready to fly again.

I don't know why the chute did not eject, perhaps it was not packed carefully enough.
IMG_1478.JPG


Special thanks to SARG for making this flight possible!
 
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Switch

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On March 4th I had another chance to fly the Falcon 9. This launch was hosted by LUNAR at their beautiful Snow Ranch site.

I didn't realize my launch was up so I almost missed it entirely. I didn't see it go up, but I certainly saw it come down, nose down. And at first I thought "boy I feel bad for that guy" then I noticed the my capsule floating by...

So yeah, it didn't go well. The things that worked were the 9 cluster ignition, ignition of the second stage, and deployment of the Crew Dracon capsule.

The rear ejection worked partially. The string that runs from the motor tube to the top of the 1st stage on the outside was loose and slid under the motor at take off and burned in half. So the motor tube shot out and left the 1st stage without a parachute. I've redesigned the external recovery line attachment to the booster to prevent this from occurring again.

Second stage recovery also failed tragically with the ejection charge burning the parachute string. Lesson learned: use more wadding & a thicker string for the parachute.

The 1stage came down ballistically destroying the BT-70 tube at the top of the 1stage. I think it worked like a crumple zone in a car & prevented more damage. The stress of the crash also tore the paper skin at the coupler between the first two BT-70 tubes, so that skin needed to be replaced as well.

The second stage, benefitting from achieving a greater altitude was completely totaled except for the Crew Dragon trunk module, which is plastic. The flip out fin/motor mount was also ruined but the fins survived.

I thought I had pictures of the wreckage but I can't find them.

I've been busy on other projects so just tonight turned to the task to repairing the Falcon 9. Tonight my efforts to avoid using glue really paid off. I was able to snap off the grid fin mounts, and remove the adhesive paper skins with a heat gun. All of the BT-70 tubes easily slid off the press-fit couplers.

Here is the top of the 1st stage before I had removed the skin with the NASA logo. The very top BT-70 was in shreds & here the replacement is being fitted.
IMG_1994.JPG

In the bottom of this photo, you can see the shear in the skin at the location of the 1st coupler. You can also see the compression stress in the skin just above the NASA logo where the 2nd BT-70 tube joins the 3D printed section with the holes for the grid fin mounts.

Parts disassembled:
IMG_1995.JPG


Time to print more skins:
IMG_1996.JPG

and apply carefully from the middle to the edges on both sides:
IMG_1997.JPG


Skin applied:
IMG_1998.JPG


Rebuilt 2nd stage flip out fins and BT-70 tube:
IMG_1999.JPG

IMG_2001.JPG


The repairs took about an hour but I only needed to replace 2 BT-70 tubes, the 2nd stage flip out fin/motor mount, and apply new skins.
IMG_E2004.JPG

This rocket is starting to look like it has flown a couple of times.
 
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Switch

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Here is the Falcon 9 at Artesia Dry Lake on 05/21/23
IMG_2093.JPG


close up of clip whip:
IMG_2094.JPG



Shortly after ignition, it suffered a catastrophic failure of the E12-0 motor:



IMG_2098.JPG


Here is my breakdown of events:
about 1/3 of a second into the launch there is an audible pop and ejection of the E12-0 motor nozzle:
1653350426054.png
The explosion forced the motor tube upward, releasing the landing legs. You can see they have started to extend in the photo above.

The explosion also severed the 9 motor cluster mount from the motor tube at the top of the E12-0 motor. Ejecting 9 motor cluster mount and motors from the rocket:
1653350558707.png
The landing legs extend completely - with their fins now lowered into the flames of the explosion.

The A10 motors continue to fire so the 9 motor cluster mount (left arrow) continues upward and was recovered behind the parking area. The explosion forced the motor tube upwards into the 2nd stage motor/flip out fin assembly, causing the 2nd stage to separate (lower right arrow) without ignition of the 2nd stage.
1653350819440.png
Fortunately, the Crew Dragon Launch Escape System was activated (upper right arrow).

1653351141717.png
And the Crew Dragon recovery worked!
1653351234687.png

So while the Falcon 9 first stage was completely destroyed, no lives were lost and a terrible tragedy was avoided.



Special thanks to Wayne, Ron, and Jennifer from Rocketry Organization of Northern Nevada for making this launch possible.
 

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waltr

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Oh NO.
The first photo is of a great looking rocket and the clear fins are invisible.

Then the CATO.....I do not fly BP E's due to the number I have seen CATO.
Good photo sequence highlighting the event.
Nice the Crew escape system worked.
 

Switch

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Oh NO.
The first photo is of a great looking rocket and the clear fins are invisible.

Then the CATO.....I do not fly BP E's due to the number I have seen CATO.
Good photo sequence highlighting the event.
Nice the Crew escape system worked.
Wayne said the same thing about BP E motors and his daughter (Jennifer) suggested using an F motor instead. I forget what make she suggested. But that it could be fitted to my E motor mounts. I need to add that to my "lessons learned" list.
 

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So here's the post mortem on the E12-0 disaster:

The nine motor cluster mount broke about 3cm from the motor stop of the E12-0. Those holes I added to reduce weight also reduce strength and I'm going to remove them, but I don't think it would have made much of a difference.
IMG_2126(1).JPG

This motor mount can in fact be reused. I just need to print a longer transition from the E12-0 motor to the BT-20 tube that carries the ejection charged to the second stage.

Also, on a positive note: all 9 motors ignited. But you can see how the E12-0 completely blew out.
IMG_2127(1).JPG


And the plugs in the tops of the A10-0T motors held.
IMG_2128(1).JPG


This is the BT-20 tube above the 9 motor cluster mount. That's the shock cord for recovery and the shattered centering ring for the shear magnets that hold the landing legs in place.
IMG_2137(1).JPG


Here I've stretched the motor tube back out so you can see the amount of compression it absorbed.
IMG_2142(1).JPG


The centering ring for the shear magnets that retain the landing legs was shattered. So it is no wonder that the landing legs deployed.
IMG_2144(1).JPG


For comparison, this is what it used to look like:
IMG_E1883.JPG


Meanwhile, the 2nd stage did not ignite and suffered no damage.
IMG_2129(1).JPG


But the 1st stage was damaged extensively. The lower 3D printed section melted, the BT-70 tube crumpled, and the landing legs and fins dropped into the fireball emanating from the bottom of the rocket.
IMG_2131(1).JPG

IMG_2130(1).JPG

But the LOX and LH2 lines, landing leg telescoping tubes, and metal screws and magnets all survived.

The interstage section was also undamaged & although a few pieces popped out, they were recovered on site.
IMG_2132(1).JPG


The recovery chute had some minor pock marks but is reusable.
IMG_2136(1).JPG


in part saved by the retainer tubes I've been developing:
IMG_2138(1).JPG


The motor tube top centering ring was also destroyed
IMG_2141(1).JPG


As were two of the landing legs:
IMG_2145(1).JPG


I've already made some improvements in the landing legs to strengthen the weak point where the screw mount is located. I've also improved the way the fins mount in the landing legs. So I reprinted all 4.

That's it for now. Time to rebuild...
 
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BigMacDaddy

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This is an amazing journey of design and persistence. I am curious about why you do not used plugged engines for the A10s (i.e., the ones made for Estes race cars).

FWIW - I designed a 3D printed cluster mount that might be appealing / interesting to you. You obviously have the design skills to do this type of thing (or something better) yourself but maybe that design will inspire a different / easier design for your motor retainers. I have not tested this with a fully loaded cluster but think that the 3D printed parts in ABS will hold up. This picture just shows the loaded canister but below I have exploded the cluster and shown the mounting parts.

1655897173543.png .

The idea is to do a quarter turn twist to lock cluster canister that can be fully loaded up outside the rocket. This requires that the top portion of cluster mount can also rotate so I use a thrust ring mounted inside the airframe and a large block across the whole top of the cluster. In the picture below the yellow parts are mounted to the airframe (or in my case were printed into the shell of a Little Joe II). I designed this to use the central 18mm engine for ejection so the mini engines are isolated from the top section of the airframe (I expected to use plugged engines but left the holes in the top in case someone wanted to use A10-0 and just load 3 instead of 6 so the other holes could exhaust the burn through. This also uses canted motors w/ an 18mm central motor but you could do the same with a 24mm in center and straight mini engines.

1655897578245.png
 

Switch

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This is an amazing journey of design and persistence. I am curious about why you do not used plugged engines for the A10s (i.e., the ones made for Estes race cars).

FWIW - I designed a 3D printed cluster mount that might be appealing / interesting to you. You obviously have the design skills to do this type of thing (or something better) yourself but maybe that design will inspire a different / easier design for your motor retainers. I have not tested this with a fully loaded cluster but think that the 3D printed parts in ABS will hold up. This picture just shows the loaded canister but below I have exploded the cluster and shown the mounting parts.

View attachment 523842 .

The idea is to do a quarter turn twist to lock cluster canister that can be fully loaded up outside the rocket. This requires that the top portion of cluster mount can also rotate so I use a thrust ring mounted inside the airframe and a large block across the whole top of the cluster. In the picture below the yellow parts are mounted to the airframe (or in my case were printed into the shell of a Little Joe II). I designed this to use the central 18mm engine for ejection so the mini engines are isolated from the top section of the airframe (I expected to use plugged engines but left the holes in the top in case someone wanted to use A10-0 and just load 3 instead of 6 so the other holes could exhaust the burn through. This also uses canted motors w/ an 18mm central motor but you could do the same with a 24mm in center and straight mini engines.

View attachment 523843
I really like your design & the idea of a locking mechanism. I only used the A10-0T because that is what I could source at the time. I've love to model the nozzles like you have, but I think they would melt unless the end of the A10 motor was flush with the bottom of the nozzle. So maybe the twist/lock could create side compression to hold the motors in place.

As for my Falcon 9, I've redesigned and reinforced all of the parts that broke and it is ready to be put back together. I'm hoping to launch again at ROCKONN in July. The 1:65 scale Falcon Heavy is also ready to fly, so it should be an interesting day.
 

BigMacDaddy

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I really like your design & the idea of a locking mechanism. I only used the A10-0T because that is what I could source at the time. I've love to model the nozzles like you have, but I think they would melt unless the end of the A10 motor was flush with the bottom of the nozzle. So maybe the twist/lock could create side compression to hold the motors in place.

As for my Falcon 9, I've redesigned and reinforced all of the parts that broke and it is ready to be put back together. I'm hoping to launch again at ROCKONN in July. The 1:65 scale Falcon Heavy is also ready to fly, so it should be an interesting day.

Thanks - I have printed a bunch of engine retainers from ABS and have not had issues with melting (although I have not tested with clusters).

Best example of the impact of mini engine is on my X-3 Stiletto where engine was directly against a partial ABS tube. Did not really melt but did definitely blacken.

1655909119323.jpeg

I also have used ABS to print D to E adapters that take the brunt of the ejection charge for a D12 engine. Also no real melting.

1655909282837.jpeg

Both of those results are after a single launch so TIFWIW.
 
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