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#1 2026-08-02 06:31:55
- tahanson43206
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No Wing Return from Orbit Cylinder Cylindrical SpaceX Starship
This topic is offered for NewMars members to contribute reports on navigation of a cylinder when returning from low Earth orbit.
As we begin this new topic, all we have to go on is a YouTube video discovered by OldFart1939, in which the claim is made that SpaceX has learned how to navigate a cylindrical space ship (Starship) to perform navigation maneuvers while returning from orbit.
If true, this would imply that a cylinder can be "flown" great distances from it's initial path.
If true, this would imply that a "wing" is NOT necessary for a reusable space vehicle to choose a landing site.
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#2 2026-08-02 06:32:31
- tahanson43206
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Re: No Wing Return from Orbit Cylinder Cylindrical SpaceX Starship
This post is reserved for an index to posts that may be contributed by NewMars members.
Index:
Post #3: Opening summary by Gemini, confirming the ability to "fly" a cylinder in Earth's atmosphere.
Post #4: Episode 1: Hypersonic Aerodynamics & Shockwaves on a Cylindrical Hull
Post #5: Episode 2: Flap Actuation & Differential Drag
Post #6: Episode 3: Thermal Protection Systems (TPS) Under Asymmetric Heating
Post #7: Episode 4: The Final Flip & Catch
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#3 2026-08-02 06:51:17
- tahanson43206
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Re: No Wing Return from Orbit Cylinder Cylindrical SpaceX Starship
In this post we begin what I hope will be a series on the physics of cylindrical flight in the atmosphere of Earth.
How to Fly a Cylinder: Series Overview
Welcome to the opening installment of our educational series!
When most people think of atmospheric re-entry for cylindrical rockets, they picture an unguided "falling rock"—a purely ballistic descent following a rigid, predetermined path. However, SpaceX's Starship upper stage breaks this mold by functioning as a giant lifting body during hypersonic and supersonic re-entry.
Here is a summary of how SpaceX "flies" a 9-meter-diameter cylinder thousands of kilometers through the upper atmosphere and away from its default impact track.
1. The Physics: Turning a Cylinder into a Lifting Body
While a cylinder is symmetrical, entering the atmosphere at an inclined Angle of Attack (AoA)—typically between 60 degrees and 70 degrees relative to the velocity vector—exposes a massive flat surface area to incoming air.
Lift-to-Drag Ratio (L/D): This orientation generates significant aerodynamic lift alongside drag.
The "Skydiver" Dynamics: Just as a skydiving human adjusts their limbs to glide forward or turn, Starship uses its four independent actuating flaps (two forward, two aft) to actively control pitch, roll, and yaw.
2. Steering Off the Default Path: Cross-Range & Down-Range
By banking the vehicle (rolling it left or right using flap deflections), the upward aerodynamic lift vector tilts to the side. This gives Starship cross-range capability—the ability to maneuver laterally away from its original orbital track.
Lateral Offset: By tilting the lift vector, Starship can steer tens to hundreds of kilometers left or right of its ballistic footprint.
Range Extension/Shortening: Adjusting the angle of attack alters total drag, extending (down-range) or shortening the flight path to hit a precise geographical window.
3. The Practical Application: Inherently Safe Trajectories
This dynamic steering is critical for safety and operational flexibility:
1. Fail-Safe Default Track: During re-entry, the passive, unguided trajectory (where the ship would go if control were lost) points safely over open oceans or uninhabited zones.
2. Active Trajectory Offset: Only after autonomous health checks confirm flap actuators, tiles, and guidance systems are functioning does Starship actively roll and trim its flaps to "glide" toward its target landing site or catch tower.Upcoming Topics in This Series
Episode 1: Hypersonic Aerodynamics & Shockwaves on a Cylindrical Hull
Episode 2: Flap Actuation & Differential Drag: How the Skydiver Control Algorithm Works
Episode 3: Thermal Protection Systems (TPS) Under Asymmetric Heating
Episode 4: The Final Flip & Catch: Transitioning from Horizontal Glide to Vertical Landing
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#4 2026-08-02 06:58:03
- tahanson43206
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Re: No Wing Return from Orbit Cylinder Cylindrical SpaceX Starship
In this installment, we begin with fundamentals the engineers face in planning navigation of a cylinder.
Episode 1: Hypersonic Aerodynamics & Shockwaves on a Cylindrical Hull
Welcome to Episode 1 of "How to Fly a Cylinder!" In our overview, we established that SpaceX's Starship isn't just falling—it's gliding. Today, we dive into the high-speed physics that make this possible: hypersonic fluid dynamics and shockwave management on a massive cylindrical airframe.
1. The Hypersonic Flow Regime
When entering the upper atmosphere at Mach 25 (roughly 7.5 km/s), air cannot move out of the way fast enough. Instead of flowing smoothly around the vehicle, the air molecules are violently compressed, creating extreme pressure and thermal environments.
Compression Heating vs. Friction: Contrary to popular belief, most re-entry heat comes from intense atmospheric compression in front of the hull rather than surface friction.
Blunt Body Theory: Formulated by H. Julian Allen, entering with a broad, blunt profile creates a detached "bow shock wave" that stands off from the hull, keeping the multi-thousand-degree plasma shock layer at a distance from the skin.
2. Converting a Cylinder into a Lifting Surface
A cylinder flying end-first (longitudinally) behaves like a needle—minimal drag, but zero lift and catastrophic heating at the tip. To "fly," the vehicle pitched up to an extreme Angle of Attack (AoA) of 60 to 70 degrees.
Effective Asymmetry: At a 60-degree pitch, the cylindrical cross-section presents a broad, semi-flat profile to the oncoming air.
Pressure Differential: High pressure builds up on the belly (windward side), while a massive low-pressure wake zone forms along the back (leeward side). This pressure differential is what generates net lift.
Cross-Sectional Lift Curve: While a flat wing is more aerodynamic, a cylinder at high AoA still achieves a Lift-to-Drag (L/D) ratio of roughly 1.0 to 1.5 in the upper atmosphere—more than enough to steer across continental distances.
3. Shockwave Interaction and "Hot Spots"
Cylindrical geometry at an angle creates complex shockwave dynamics that directly influence vehicle stability and heat shield design:
Bow Shock Detachment: The primary shockwave forms a high-pressure cushion along the entire ventral (belly) surface.
Flap Shock Impingement: Where the main bow shock interacts with the deflected control flaps, local compression spikes. These "shock-on-shock" interactions generate hyper-localized thermal hotspots, requiring extra thermal tile reinforcement around the flap hinges.
Leeward Vortices: Low-density recirculation eddies form on the top of the cylinder, keeping that area cool enough to leave unshielded stainless steel exposed.
Key Takeaway for the Forum
Flying a cylinder isn't about streamlined efficiency; it's about brute-force pressure manipulation. By holding a massive 9-meter cylinder at a steep angle, Starship uses a detached shockwave to push thousands of degrees of plasma away from its body while riding the high-pressure cushion underneath.Next Up in Episode 2
Flap Actuation & Differential Drag: How four independent flaps balance pitch, roll, and yaw without a traditional rudder or tail fin.
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#5 2026-08-02 07:04:57
- tahanson43206
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Re: No Wing Return from Orbit Cylinder Cylindrical SpaceX Starship
This is Episode 2 of a series on "flying" a cylinder from orbit. The series is prepared by Gemini as supervised by tahanson43206.
Episode 2: Flap Actuation & Differential Drag
Welcome to Episode 2 of "How to Fly a Cylinder!" In Episode 1, we explored how pitching a cylindrical hull creates a high-pressure cushion of air to generate lift and deflect extreme heat.
Today, we examine how Starship actually controls that flight. Without a traditional vertical tail fin, rudder, or jet-like wings, how does a giant cylinder steer, roll, and balance itself?
1. The "Skydiver" Paradigm
The easiest way to visualize Starship's control strategy is to picture a human sky diver in belly-flop position:
Independent Actuation: Starship features four large body flaps—two forward and two aft—driven by high-torque electric motors.
Belly-First Orientation: Rather than using aerodynamic surfaces to cut through the air, the flaps extend outward to create intentional, controlled drag.
Center of Mass vs. Center of Pressure: By fine-tuning the angles of all four flaps simultaneously, the flight computer continuously shifts the vehicle's center of aerodynamic pressure relative to its center of mass.
2. Three-Axis Flight Control via Differential Drag
Instead of traditional ailerons and elevators, Starship uses "differential drag"—varying the aerodynamic resistance on different corners of the ship—to control pitch, roll, and yaw.
Pitch Control (Nose Up / Nose Down): To pitch up, the forward flaps actuate inward (reducing front drag) while the aft flaps extend (increasing rear drag). To pitch down, the opposite occurs.
Roll Control (Banking): To roll left, the right-side flaps actuate inward while the left-side flaps push outward into the windstream. The unequal drag tilts the ship into a roll.
Yaw Control (Side-to-Side Heading): Yaw is controlled through asymmetric cross-body actuation, using opposite diagonal pairs of flaps to twist the hull into the airflow.
3. Flying Off-Course: The Cross-Range Maneuver
This flap actuation scheme is the key to turning a simple cylinder into an off-track glider:
Tilting the Lift Vector: By using the flaps to roll the ship left or right while maintaining a high angle of attack, the upward lift generated on the belly is redirected sideways.
Steering Tens of Miles: This lateral lift actively pushes the ship across the sky, allowing it to navigate around weather systems or adjust its trajectory toward a precise landing pad far from its unpowered ballistic splashdown point.
Key Takeaway for the Forum
Starship doesn't fly like an airplane using smooth, streamlined lift. It flies like a sky diver using differential drag—constantly trimming its four flaps to balance on a cushion of air and lean side-to-side to steer across the sky.Next Up in Episode 3
Thermal Protection Systems (TPS) Under Asymmetric Heating: How 18,000 hexagonal ceramic tiles shield the cylinder, and how the flap hinge gaps survive the plasma torch.
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#6 2026-08-02 07:11:04
- tahanson43206
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Re: No Wing Return from Orbit Cylinder Cylindrical SpaceX Starship
This is Episode 3 of a series on how to fly a cylinder through Earth's atmosphere... Prepared by Gemini Supervised by tahanson43206
Episode 3: Thermal Protection Systems (TPS) Under Asymmetric Heating
Welcome to Episode 3 of "How to Fly a Cylinder!" In Episode 2, we examined how Starship uses differential flap drag to steer like a skydiver. Today, we look at how the vessel survives the brutal thermal environment created by hypersonic re-entry.
When flying a cylindrical hull at a steep angle of attack, thermal management becomes a game of extreme asymmetry: one side endures a furnace, while the other sits in relative cool.
1. The Asymmetric Thermal Environment
Because the cylinder enters the atmosphere belly-first at a 60 to 70 degree Angle of Attack (AoA), heating is far from uniform across the body.
Windward (Belly) Surface: Directly exposed to the compressed plasma shock layer, temperatures on the belly reach upwards of 1,400 degrees Celsius (2,500 degrees Fahrenheit).
Leeward (Back) Surface: Because the cylinder's bulk shields its top side from the oncoming airstream, a low-pressure wake zone forms. Temperatures here remain cool enough that bare, unshielded stainless steel can handle the ambient heat without melting.
2. The Shield: Hexagonal Ceramic Tiles
To protect the windward side, the hull is covered in roughly 18,000 silica-based ceramic tiles.
Hexagonal Geometry: Hexagons are used instead of traditional square tiles because they eliminate long continuous straight seams ("runway gaps") where hot plasma could easily channel through to the steel hull.
Mechanical Attachment: The tiles are mounted using specialized mounting pins over a layer of thermal insulation blanket, allowing for quick replacement and accommodating the thermal expansion of the underlying steel structure.
3. The Hardest Problem: Flap Hinge Gaps & Shock Impingement
While protecting a smooth cylinder is relatively straightforward, protecting moving joints on a cylinder is immensely complex:
The Flap Gap Torch: Where the actuating flaps meet the main hull, small gaps are necessary for movement. During high-velocity re-entry, high-pressure plasma tries to force its way into these gaps like a blowtorch.
Shock-on-Shock Heating: As the bow shock off the main body collides with the shock wave generated by an extended flap, local compression spikes sharply. This creates intense localized "hot spots" near the hinges, requiring secondary seals, flexible thermal barriers, and reinforced ceramic tiles around the joint assembly.
Key Takeaway for the Forum
Flying a cylinder asymmetrically allows engineers to put thermal protection on only one half of the vessel—saving massive amounts of weight. However, it shifts the primary engineering challenge from the body itself to the moving flap hinges, where shockwaves collide and plasma attempts to breach the hull.Next Up in Episode 4
The Final Flip & Catch: Transitioning from horizontal hypersonic glide to vertical subsonic landing, and the dynamics of catching a cylinder with tower arms.
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#7 2026-08-02 07:17:59
- tahanson43206
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Re: No Wing Return from Orbit Cylinder Cylindrical SpaceX Starship
This is Episode 4 on how to fly a cylinder ... Text is by Gemini supervised by tahanson43206
Episode 4: The Final Flip & Catch
Welcome to the final installment of our "How to Fly a Cylinder" series! In Episodes 1 through 3, we explored hypersonic aerodynamics, differential flap control, and thermal protection. Today, we cover the dramatic grand finale: transitioning a 50-meter-tall cylinder from a horizontal hypersonic glide to a vertical, pinpoint touchdown.
1. The Subsonic Transition & "Belly-Flop" Terminal Descent
As Starship bleeds off its orbital velocity, it passes through the supersonic and transonic regimes, settling into a stable, horizontal subsonic fall.
Terminal Velocity Control: By maintaining a broad, flat profile against the oncoming wind, the hull acts like a giant sky diver, holding terminal velocity down to roughly 200 km/h (125 mph)—far slower than a traditional capsule or winged vehicle.
Precision Trimming: The flight computer continually micro-adjusts the four independent flaps to keep the ship stable, level, and on target as it falls through low-altitude wind layers.
2. The Belly-Flop to Vertical "Flip Maneuver"
A horizontal attitude is ideal for shedding energy, but a rocket must land vertically on its tail. Converting high-drag belly-first flight into engine-powered vertical flight in a matter of seconds is one of the most radical maneuvers in aerospace history:
Raptor Ignition: Just hundreds of meters above the ground, a subset of Raptor engines ignite while the ship is still falling horizontally.
Gimbal Torque & Flap Coordination: The engines vector (pivot) aggressively to swing the heavy tail down, while the forward flaps push fully open to catch the air and pitch the nose up.
Center-of-Gravity Shift: Fuel is rapidly pumped into dedicated header tanks in the nosecone to control the center of mass, allowing the ship to pendulum into a stable vertical alignment within seconds.
3. The Tower Catch Dynamics
Instead of carrying heavy, drag-inducing landing legs, Starship relies on giant mechanical arms—nicknamed "Mechazilla"—mounted on the launch tower to catch it in mid-air.
Catch Pins & Load Distribution: The cylinder is equipped with reinforced load-bearing hardpoints (catch pins) just below the forward flaps.
Hover & Settle: Using high-thrust, fast-throttling Raptor engines, the guidance computer brings the vessel into a precise zero-velocity hover between the tower arms.
Kinetic Dampening: The tower arms close around the body, catching the pins and absorbing the remaining downward momentum, bringing the cylinder to a complete, safe rest.
Series Conclusion
Flying a cylinder is a revolution in reusability. By combining lifting-body physics during re-entry, skydiver-style flap control, and a powered vertical flip for a tower catch, SpaceX turns a massive steel tank into a fully steerable, precision-guided orbital transport.Thank you for following along with our educational series!
I'll pause here to give forum members an opportunity to think of questions they'd like to ask, or perhaps contributions to the collection of knowledge about cylindrical flight.
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#8 2026-08-02 10:25:15
- Void
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Re: No Wing Return from Orbit Cylinder Cylindrical SpaceX Starship
I have a request. Where is that video? I have had a dream that Starship could leave its cargo compartment in orbit and that the "Locomotive", could enter the atmosphere and land. Of course, the ship needs a pointed nose to launch though the atmosphere.
But if you could literally land a cylinder, without a nose/cargo section, you bring back the method of locomotion of the Starship while reducing it's dry mass, so then not needing as much propellant to land. Reducing quantity of landing propellants, reduces the amount that has to go to orbit, so then you have more cargo capacity.
I am willing to delete this post if you wish, but do you have that video as reference materials?
Ending Pending 
Be careful what you wish for.
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#9 2026-08-02 12:13:35
- tahanson43206
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Re: No Wing Return from Orbit Cylinder Cylindrical SpaceX Starship
Void's request in post #8 may have value to everyone:
This post by Oldfart1939 is where the link to "Ellie in Space" may be found:
https://newmars.com/forums/viewtopic.ph … 42#p240642
I just watched an "Ellie in Space" episode with Joe Tegtmeyer which is a very good explanation of some Orbital Mechanics for Idiots. (Myself included!). Here's the link to the YouTube presentation. The length of the upcoming Flight 14 discussion covers the length of time the flight will probably take to watch the whole thing unfold. The discussion of the effects of the Earth's rotation on the proposed landing site is nicely explained with some decent engineering details--simplified version.
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