1/26th Scale Space Shuttle (full stack)

[Bravo52]

Aligning the aft fuselage parts

So, yeah, the rear fuselage has a lot going on. Here's a Fusion 360 visualization of the rear fuselage and neighboring systems (wings, retracts, etc.). I decided to use the rear fuselage mold to help with aligning all the parts, because of the angularness of the aft fuselage.

View attachment 620409

Quick question. Do you colorize your components as you design them in Design mode or do you do it in Render mode?

 

[sambatterman]

Quick question. Do you colorize your components as you design them in Design mode or do you do it in Render mode?

I use design mode.

 

[burkefj]

Are you considering doing a smaller scale model to fine tune the thrust line of the single tank mounted motor, or is the stack going to be light enough to try the simplest form of boost, just a single motor in the tank only before you add in complexity of off center srb thrust lines and associated risk in them starting at slightly different times or is it so heavy it must have all three at least to boost safely the first time?

I won't give you crap about weight, designs can have very different approaches. At approx 48 ounces per square foot or more wing loading for your shuttle is getting near turbine powered jet class of wing loading assuming some fuse lift, you'll want extremely robust gear and mounts and hopefully a smooth landing surface to survive the landing speeds and loads. For one large example Dave Shaefers 1/5 X-2 model had about 32 ounces/sq foot glide weight not including fuse lift but it had a longer span narrower chord which is a bit more efficient, it only used a nose gear and scale skids in the back. I don't know what Andy's orbiter weighed but reports on glide tests were 2:1 best glide angle and 4:1 flare...I'm sure yours will be similar.


Frank

 

[sambatterman]

Hi Frank - thanks for your message. The cold, hard reality about my project is that this orbiter may not ever fly - think Enterprise over Atlantis. I have never built a rocket with 3D Molds and Carbon Fiber skin; I have never built anything with a retractable landing gear or doors. This was a concept model to get those skills in line. I also need a physical "twin" to go along with the "digital twin" for controlling this in recovery mode. It will take years to accomplish this goal, but I needed to start somewhere - and I know that these issues will take a while to iron out. Getting everything aligned and understanding how to support the shuttle on the External Tank, where the sensors need to go, how to attach and separate the orbiter from the ET are all hard problems getting solved along the way. As I move forward, getting models to weigh less will be a goal.

 

[burkefj]

Hi Frank - thanks for your message. The cold, hard reality about my project is that this orbiter may not ever fly - think Enterprise over Atlantis. I have never built a rocket with 3D Molds and Carbon Fiber skin; I have never built anything with a retractable landing gear or doors. This was a concept model to get those skills in line. I also need a physical "twin" to go along with the "digital twin" for controlling this in recovery mode. It will take years to accomplish this goal, but I needed to start somewhere - and I know that these issues will take a while to iron out. Getting everything aligned and understanding how to support the shuttle on the External Tank, where the sensors need to go, how to attach and separate the orbiter from the ET are all hard problems getting solved along the way. As I move forward, getting models to weigh less will be a goal.

That's fair, I've recently been doing my own building, scaling and lightening of shuttles as I learn. As much as you plan and draw things there is never any way to avoid all of the gotchas that crop up when actually building something, or just the stupid mistakes

 

[Blast it Tom!]

You know, I've been thinking about a thread along the lines of "What would be your 'Build of a Lifetime (BOAL)"?" I think you've found yours! I consider myself lucky if I can find the time to get a coat of paint on something!

 

[ReynoldsSlumber]

I decided to go with outer and inner elevons just like the real thing. We'll see if it's overkill.

Think this was the right move. With unified elevons, you could get into deflection saturation if say you were pulling hard up elevator and then needed to turn at the same time. I think there's some fancy mixing nowadays that can help deal with that, but your model is complex enough as it is! With separate surfaces, the most effective portion for roll, toward the wingtip, is dedicated aileron, leaving the dedicated elevator portion unfettered. And there's the added benefit of scale accuracy.

Meanwhile, not sure how much a moving body flap would contribute, since of course its upper surface isn't doing anything, with only the lower surface contributing to pitch moment. Though, the body flap being further aft than the wing elevons and therefore on a longer moment arm, it might be worth trying on a smaller boilerplate glider test model, dunno.

Apparently on STS-1 the elevons and especially the body flap saw major deflections during boost, due to aeroacoustic as well as aerodynamic pressure. Of course model conditions aren't anywhere near as harsh, and I'm sure you've got it covered, but erring on the strong side for servo choice could be prudent, especially on the inboard elevons.

 

[sambatterman]

Think this was the right move. With unified elevons, you could get into deflection saturation if say you were pulling hard up elevator and then needed to turn at the same time. I think there's some fancy mixing nowadays that can help deal with that, but your model is complex enough as it is! With separate surfaces, the most effective portion for roll, toward the wingtip, is dedicated aileron, leaving the dedicated elevator portion unfettered. And there's the added benefit of scale accuracy.

Meanwhile, not sure how much a moving body flap would contribute, since of course its upper surface isn't doing anything, with only the lower surface contributing to pitch moment. Though, the body flap being further aft than the wing elevons and therefore on a longer moment arm, it might be worth trying on a smaller boilerplate glider test model, dunno.

Apparently on STS-1 the elevons and especially the body flap saw major deflections during boost, due to aeroacoustic as well as aerodynamic pressure. Of course model conditions aren't anywhere near as harsh, and I'm sure you've got it covered, but erring on the strong side for servo choice could be prudent, especially on the inboard elevons.

Body flap is static - no motion at all, but scale - it's definately behind the elevons, just as the real thing. Getting back to the shuttle this weekend. Gear doors and retracting gear installed!