Space Shuttle (scratch build)

[hermanjc]

I would like to add to my fleet of scale scratch builds. Next up, the Space Shuttle. And just because I like to make things way more complicated than they have to be, I plan to have 18mm motors in the SRBs, with a 24mm motor in the orange fuel tank. The SRBs will separate at burnout (similar to the Falcon Heavy I built). The basis of the design is the Estes 1284 model (from the 80s-90s I think) that had just the single motor in the orange fuel tank, and a shuttle that would separate and glide at ejection (which I will also attempt). I am upscaling it 1.5X to use a 3" scratch tube for the fuel tank. SRBs will be 1.3" scratch tubes (or maybe BT-55s if I don't want to make them from scratch). The shuttle itself will be built around a 2" body tube.

I do have a question for the TRF community on this one. In order to be stable, the Estes kit needed to have large fins at the bottoms of the SRBs. Since I plan for these to breakaway and the center motor to continue to burn, I am going to need the fins to be attached to the center tank. My first thought is to use a lightweight boom (carbon fiber perhaps) with V-tail fins. I have modified and upscaled a Rocksim file found on rocketreviews and at first blush this might just work (will require some nose weight). Does anyone here have any similar build experience with a "tail boom" like this? I have never worked with carbon fiber, and hoping a small tube (maybe 4mm OD, 2mm ID) will be sufficient. Thoughts? Should I at least rotate the fins away from the flame?

 

[mo2872]

I have no answers for you, but as a "built the Estes version twice with zero perfect flights" guy.........FOLLOWING WITH EXTREME INTEREST.......

 

[Kelly]

I like the idea. "Yes" on rotating the fins - keeps them out of the exhaust, in a better airstream, and away from the boosters when they separate.

 

[stantonjtroy]

George Gassaway did a similar set up on his shuttle. True work of art. He came up with solutions to every problem you could imagine. His shuttle page: https://www.georgesrockets.com/GRP/Scale/SHUTTLE.htm Hopefully he'll see this thread and chime in.

 

[hermanjc]

George Gassaway did a similar set up on his shuttle. True work of art. He came up with solutions to every problem you could imagine. His shuttle page: https://www.georgesrockets.com/GRP/Scale/SHUTTLE.htm Hopefully he'll see this thread and chime in.

This is awesome! Thank you very much for providing this. I will have to dive in. From a quick glance at that site I can guarantee you that my end product will not live up to the "work of art" status George G set as a very high bar

 

[BABAR]

I would like to add to my fleet of scale scratch builds. Next up, the Space Shuttle. And just because I like to make things way more complicated than they have to be, I plan to have 18mm motors in the SRBs, with a 24mm motor in the orange fuel tank. The SRBs will separate at burnout (similar to the Falcon Heavy I built). The basis of the design is the Estes 1284 model (from the 80s-90s I think) that had just the single motor in the orange fuel tank, and a shuttle that would separate and glide at ejection (which I will also attempt). I am upscaling it 1.5X to use a 3" scratch tube for the fuel tank. SRBs will be 1.3" scratch tubes (or maybe BT-55s if I don't want to make them from scratch). The shuttle itself will be built around a 2" body tube.

I do have a question for the TRF community on this one. In order to be stable, the Estes kit needed to have large fins at the bottoms of the SRBs. Since I plan for these to breakaway and the center motor to continue to burn, I am going to need the fins to be attached to the center tank. My first thought is to use a lightweight boom (carbon fiber perhaps) with V-tail fins. I have modified and upscaled a Rocksim file found on rocketreviews and at first blush this might just work (will require some nose weight). Does anyone here have any similar build experience with a "tail boom" like this? I have never worked with carbon fiber, and hoping a small tube (maybe 4mm OD, 2mm ID) will be sufficient. Thoughts? Should I at least rotate the fins away from the flame?

View attachment 433528
View attachment 433529

A ring fin or a “box” fin might provide the surface are you need to keep the fin surfaces out of the three nozzle blasts.

 

[Charles_McG]

My build thread with similar goals.

https://www.rocketryforum.com/threads/lpr-space-shuttle-build-just-for-neil_w.143731/

 

[hermanjc]

The tubes have been rolled, and recently I purchased a 3D printer, so I'm taking advantage and have printed the nose and aft closure for the center external tank and the nose cones and nozzles for the solid rocket boosters. Looking good so far. Next going to print booster release parts.

 

[GlenP]

... Thoughts? Should I at least rotate the fins away from the flame?...

View attachment 433528
View attachment 433529

hard to tell from those side views, but what does that look like in a top or bottom view? Do the fins extend beyond the frontal shadow of the ET and SRBs? They should, or they won't be aerodynamically effective in their wake. The fins drawn here might need to be longer going in that direction.

 

[hermanjc]

After a break from model building for a while, made some progress on the Shuttle build. Motor mount assembled for the External Tank (will take a 24mm motor), and setup the tail fin boom to be able to be threaded into the aft closure to allow for it to be removed for better display when not flying. The white parts pictured were 3D printed, and the tail boom is a fiberglass rod from a Dollar Tree wind spinner. Total weight so far for the ET is 98g.

Goal this week is to mount the release hooks for the SRBs to the ET, and install the 18mm motor mounts in the SRBs. Also need to start 3D model/print of the Orbiter Vehicle nose. The rest of the body will be tube and balsa for wings and tail with paper wrap to shape the fuselage.

 

[hermanjc]

Great progress last night. Motor mounts installed for the ET and SRBs. Also the SRB release hooks are on and functioning great. Total length without fin boom is 21.5", with the fin boom it is 28". Now I can focus on the Orbiter Vehicle and updating my Rocksim model to reflect my actual measured properties so I can size the fins.

 

[hermanjc]

Orbiter Vehicle is progressing nicely. Need to glue up the cardstock wrap over the tube for fuselage shape and then glue on the vertical stabilizer. Then design, print and attach the release hooks.

Cardstock mockup of wings/stabilize to check the scale appearance


Balsa and papered wing glued with cardstock wrap in progress. 3D Printed nose just taped on currently, may add some nose weight if I have any chance of trimming this thing to glide.

 

[hermanjc]

Ext Tank supports added, and printed and attached the release hooks/receivers. Got out my scratch made Saturn V and Falcon Heavy for a quick comparison. All 3 models are between 1/100 - 1/115 scale. Now time to really dig into my Rocksim model to match the weight/CG and size the fins for the boom.

 

[neil_w]

Just curious, how much does the orbiter weigh?

 

[hermanjc]

Just curious, how much does the orbiter weigh?

The Orbiter is 2.7oz (76g) of dead weight right now. Still going to add some final embellishments and paint. My mind is quickly abandoning any hope of "glide return", and thinking of ways to add in a delay parachute, possibly using a Tomy Timer method that I have used in the past for water rocket parachute deployment.

 

[hermanjc]

Aside from paint, the shuttle orbiter vehicle aesthetic design is done (added nacelles and nozzles).


I am resigned to the fact that this OV will not glide, at least not in any safe manner, and as such I am now adding a hatched door into the cargo bay to allow a delayed release of a parachute. Hinges and Doors were 3D printed and use a paperclip to pivot. Adding 3D printed bulkheads to make sure the parachute doesn't fall aft/forward.



The delay will be controlled by a "tomy timer" from a kids wind up toy. It will stick out of the bottom, and after the OV releases from the ET, the timer will be released to spin, resulting in approximately 2-3 second delay before a rubber band over the doors releases for cargo bay opening. I plan to make a soda bottle spring to compress with the doors shut to pop the parachute out into the airstream more effectively.

 

[Nytrunner]

I am resigned to the fact that this OV will not glide,

Just like the real thing!

 

[AfterBurners]

Nice work!

 

[Raptor 2]

looking forward to launch day

 

[Charles_McG]

You got me curious about what my Orbiter weighs. 42.7g with electronics and battery.

 

[hermanjc]

You got me curious about what my Orbiter weighs. 42.7g with electronics and battery.

Yeah... Definitely not the lightest build on my part. Over 100g now and don't have paint or parachute yet... Good news is with a D12 in the ET and 2 x C6s for the SRBs I'll have over 600g's of (recommended) liftoff weight. Could even increase that with C5s if needed. One thing is for sure... This won't set any altitude records

 

[Nytrunner]

Now you just need to get one of Frank Burke's Buran gliders and check the balance. Maybe that'll help you get this one to glide!

 

[hermanjc]

OV parachute delay release mechanism complete and functioning well. Rocksim model is just about complete. Time for paint!

 

[GlenP]

I have thought of using a similar wind-up toy like that to spin around a little offset weight around the axle on a glider, so when the glider returns it kind of turns left/right and dives/climbs a little. Might make for a more interesting glide with that slight bit of c.g. shifting around. Alternately, it could connect to a control horn attached to moveable surfaces.

 

[hermanjc]

Paint is on. Going to create and print some water slide decals to pretty it up some.

 

[hermanjc]

Decal mockups (courtesy of https://www.axmpaperspacescalemodels.com/) wrapped around the SRBs and ET. Need to make a couple tweaks to size them just right, and then will print on waterslide paper. The shuttle will probably be hand painted for the black areas, with wing decals applied.

 

[hermanjc]

Paint and decals done. Just need to add fins to the boom, finish parachutes and wait for a warm spring day.

 

[GlenP]

Nice set of rockets! In looking at the clear fins on the SpaceX rocket, and the larger than scale fins on the Saturn, I am getting an idea. For a Saturn V use clear fins larger then scale, but paint them on a portion that is the size of the smaller scale fin outline. Just an idea, kind of like how the old Centuri kit came with clear extended fins that slid onto the scale fins.

 

[Nytrunner]

Paint and decals done. Just need to add fins to the boom, finish parachutes and wait for a warm spring day

Looking forward to hiw that shuttle flies+

 

[hermanjc]

Nice set of rockets! In looking at the clear fins on the SpaceX rocket, and the larger than scale fins on the Saturn, I am getting an idea. For a Saturn V use clear fins larger then scale, but paint them on a portion that is the size of the smaller scale fin outline. Just an idea, kind of like how the old Centuri kit came with clear extended fins that slid onto the scale fins.

Agreed. The Saturn V was my first scratch build, and those fins snap very easily (I didn't realize grain orientation was important... Now I know). I'm considering trimming them to scale and adding the necessary area back with polycarbonate. Or even better... Starting a new build so I can use a 24mm motor for the center engine, as right now it takes 3 x 18mm.

Looking forward to hiw that shuttle flies+

Me too... Although a bit nervous. This will certainly be a "heads up" maiden.