BlackStar TSTO build
 

BlackStar TSTO Description:

This model is loosely based on Lockheed/Martin design studies for a two stage to orbit (TSTO), reusable space transportation system done in the late sixties. It consisted of a Carrier Vehicle and Orbiter stack that sled launched. The Carrier Vehicle had air breathing engines for fly back recovery and horizontal landing. The Orbiter was also recovered to a runway. Something similar was rumored to be operating out of Groom Lake about 16 years ago under the code name BlackStar.

The model will be flyable in three different configurations. Configuration 1 is being built now and will be covered in this thread.

Configuration 1 - R/c Orbiter glider / Rear ejection, parachute recovery Booster.
Power: AeroTech E15-WP in the Obiter. AeroTech F20-3W in the Booster.

Configuration 2 - Free-flight Orbiter glider / R/c Carrier Vehicle glider.
This was my prototype built back in 1986. Flown once but never successfully recovered. The stack failed to separate after a perfect boost... it augured. The attached photos were taken after it was re-built, but never flown again.
Power: To be determined… the original used one 24mm and one 29mm AeroTech SU motor. (for the life of me, I just can’t remember which ones). They did have the characteristic thrust/time curves of “long burn” motors in use today. The Orbiter motor ejected with streamer recovery and I’m not sure I want to do it that way this time around.

Configuration 3 - R/c Orbiter glider / R/c Carrier Vehicle glider.
Power: AeroTech E6-RCT in the Obiter. AeroTech G12-RCT in the Carrier Vehicle


More photos to come… but for now, enjoy these.

Regards,


FlyBack

Configuration 1 mockup phase
 

One critical aspect of this design is locating the 3D center of gravity. Mockups help me do that. With an asymmetrical configuration like this one, simply pointing the motor thrust lines through the C.G. isn't enough. You have to use some math. The vector equations for static equilibrium are written around a known C.G. Summation of forces on the Z axis and summation of moments about the C.G. must equal zero. That requires some trig.

I am so dying to see this one finished and flown! :D

Glider test model
 

...Not exactly a mockup. A test model built from 6mm depron foam and .010in vacu-formed plastic. Sometimes called a "toss model" or "chuck glider". This one allowed me to confirm the C.G. and elevon deflections for the Orbiter R/c model. Oh, and yes, it flies! Glide ratio is about 8 to 1. Not bad for a low aspect ratio delta wing with a blunt body tail.

Launch rail
 

Rail mods finished. The outriggers fold inward for transport. The rail itself is 96 inches long. Why so long? In order to keep acceleration below about 5 g's I'm using long burn motors (higher accelerations would rip the wings off or induce flutter... a bad thing). Critical velocity when it clears the rail is about 35fps. IF I meet my weight targets, RocSim says it will be going 35fps at the 84 inch mark. I don't trust RocSim.

Finish it... Fly it
 

You and me both! I figure I have about six weeks...to make the contest that is. You'd think after twenty-three years I would be a little further along. :chuckle:

Regards,

DJ Miller

A most challenging but equally rewarding project! In either or both (or neither?) of your models, is/was the orbiter's motor ignited in flight so that it flies/flew free as a true second stage, or are/were the booster's motor and the orbiter's motor ignited simultaneously at launch as a cluster?

Staging
 

Black Shire

In all three configurations both motors are ignited at the same time (like a cluster). A hold back system is required. The E7-RCT orbiter motor burns slightly longer than the E15-4 booster motor. That makes it a 1 1/2 parallel stage rocket. Separation occurs when the rear ejection parachute deploys from the booster stage. The orbiter motor remains with the orbiter.

The two motors used have different impulses and average thrusts. As a consequence, they have different offsets from the vertical C.G. and also different thrust line angles. Getting that part right is a real B... err, challenge.

Regards,

DJ Miller

Thank you for clarifying this. Having done a bit of preliminary design work (which convinced me that I needed more mathematical design tools than I had at the time) for a flying model of Max Faget's original "DC-3" TSTO Space Shuttle, the last part of your comment feels very familiar... :-)

Booster assembly
 

...just a few photos of the booster before final assembly. Tested the rear ejection system on the Fourth of July without any structural failures, scared neighbors, chared chutes or local police showing up. Worked as designed.

Next step will be installing the mating pins on the two wings. Tooling is complete, just need the time.

Regards,

DJ