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Questions tagged [aerodynamics]

the effect on a spacecraft of moving through atmosphere, how its density, pressure, temperature, flow velocity, and viscosity affect a craft, and how lift and drag can be used to modify that.

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Are there any advantages to being a smaller spacecraft for reentry?

Could a ship drop its cargo or shed weight before reentry to lessen the strain on the ship during reentry? Would a ship breaking down to smaller parts before reentry have any advantages over being one ...
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51 views

Understanding Coefficient of Drag Verses Mach Number for Launch Vehicles

I've been working on a design for a sounding rocket that can go to the Karman line, that I want to make my senior capstone project next year. As a part of this process, I am making a program to ...
3
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1answer
115 views

Would an autogyro be a good solution for a space re-entry vehicle?

From what I can imagine, using an autorotative maneuver as a re-entry control method would be a good idea because I believe very high lifts would be generated when relative air speed is high (first re-...
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2answers
103 views

How do the dynamic pressure evolves during reentry?

During launcher ascent, dynamic pressure evolution is describe in this answer for the Saturn V. I suppose this is comparable from one launcher to another. Given the protections designed for reentry, ...
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2answers
157 views

Can it be calculated that within the Kármán boundary the lifting force equals the centrifugal force?

According to Wikipedia about the Kármán line: In the final chapter of his autobiography Kármán adresses the issue of the edge of outer space: ...or 24 miles up. At this altitude and speed, ...
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2answers
196 views

Drawbacks and advantages of two slidable & rotatable control surfaces for BFS sized spaceships

BFS (SpaceX's Big Falcon Spaceship) is in development and has seen between 2016 and 2018 three major design modifications. January 2018 I asked here how BFS planned to manoever during aerobraking. ...
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2answers
418 views

Is the definition of the Kármán line from Wikipedia right? [closed]

Edit: this question is about making clear that the Wikipedia's article about the Kármán line is an interpretation, not the definition ! Why not consider the Kármán line as a curved boundary that ...
9
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2answers
210 views

Why does in-flight mission abort often ends in ballistic high-$g$ reentry?

I am seeing a lot of references to the “ballistic reentry” mode of the crew return vehicle in relation to the abort during the powered ascent stage. In partiulat, the recent crewed Soyuz MS-10 abort ...
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Did the Shuttle have a drag penalty for ascent with a negative angle of attack (AOA)?

@OrganicMarble's answer mentions Because the Orbiter wings developed lift at zero angle of attack, the high dynamic pressure portion of ascent had to be flown at a negative angle of attack, close ...
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8answers
5k views

How would a long pole be transported to space?

Can a long pole or a set of poles be strapped to the out side of a rocket (like a bottle rocket)or on the nose as an external payload without interfering with the aerodynamics of the rocket? How would ...
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1answer
248 views

What is the terminal velocity on Mars?

How would I calculate the terminal velocity of Mars? Bonus: Could entry of Mars with balloons work like this similar to the linked question?What would the BFS' landing on Mars be like, if it is ...
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4answers
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What causes a rocket to be destroyed during launch other than leaking fuel?

There were some famous accidents where rockets launched and just went up into flames. Many had something to do with leaking fuel in some sort. I want to focus on aerodynamic stress however, like when ...
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Aerobraking on Mars

I am looking for a calculator or formulas that can be used to calculate the aerobraking on Mars mission. I have found some data on previous Mars flights where aerobraking was used and all my current ...
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2answers
282 views

Aerodynamically - can a rocket be over 30 meters in diameter?

The past and current designs of rocket launchers have diameters up to 8-10 meters (Saturn-5, N-1, SLS, BFR), up to 13-14 meters for max cross-section dimension for Space Shuttle and Energia-Buran (...
2
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0answers
63 views

Falcon fairing half - between separation and parachutes deployment

How does Falcon fairing half behaves in atmosphere before parachutes deployment? What is its free fall attitude in atmosphere? Is the fairing's attitude stable (with some wobbling, but without ...
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3answers
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+200

What would a “Kármán plane” look like, a bird, or a plane?

If I understand correctly (which I might not), the Kármán line is roughly the altitude where a "Kármán plane's" upward lift force at the orbital velocity for that altitude would be equal in magnitude ...
4
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1answer
353 views

Can a reentry be done slowly?

The usual approach to reentry is fast and hot. There's a lot of energy to be lost, and doing it quickly has some advantages: You can dump energy into hypersonic air, and then leave that heat behind ...
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1answer
335 views

Could Space Shuttle's wings be diminished?

From Wikipedia The crucial factor in the size and shape of the Shuttle orbiter was the requirement that it be able to accommodate the largest planned commercial and military satellites, and have ...
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3answers
364 views

What are these circular structures around the rocket?

Youtube video of the Iridium-6/GRACE-FO NASA Launch (Falcon 9 SES-12). Edit 31 May: Too bad they have changed the content of the video (and still call it 'live'), so that you can no longer see the ...
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1answer
224 views

Why would a significant non-zero angle of attack be an advantage during 1st stage burn?

From videos of both the SES-10 launch shown in @RusselBorogrove's question, Cause of apparent plume deflection on SES-10?" and the Block 5 launch Bangabandhu Satellite-1 Mission at ...
18
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1answer
5k views

Why is Falcon 9's fairing so big?

The Falcon 9 fairing costs millions of dollars. It is 5.2 meters wide while the rocket itself is only 3.7 meters wide. There is no aerodynamic reason that the fairing has to be so big, since Dragon ...
2
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1answer
469 views

Would a balloon pop if dropped from space?

Could a inflated party balloon be dropped from space and not make it to the the ground intact although flat and deflated from air pressure? or A sturdy balloon is inflated with helium/oxygen to ...
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4answers
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Why are the bottom of most stages flat?

When looking for rocket engine images, I noticed that the bottom of the stages are almost flat. That does not seem aerodynamic. I understand this is not a primary concern for upper stages (mainly ...
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2answers
3k views

Why not jettison the nose-cone from Falcon Heavy side boosters for better control authority?

With February 6th's launch of Falcon Heavy we saw the landing of both side boosters. During the past few weeks and again in the press conference today I've heard over and over about the increased ...
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0answers
41 views

Atmospheric Entry Vehicle: Wind frame representation and Visualization

I am looking at entry dynamics for a convex blunt aeroshell. We use Heading angle, bank angle and flight path angle for description of attitude from local horizon axes system. While it is sufficiently ...
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1answer
215 views

Would a dimpled heat shield reduce heat transfer during reentry?

Would a large ceramic golfball absorb less heat on reentry than a standard sphere? From aerospaceweb.org: The difference in the flowfields around a smooth sphere and a rough, or dimpled, sphere ...
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What aerothermal effects present significant challenges in supersonic retropropulsion?

One of NASA's plans for future mars entry, descent and landing missions includes an ambitious deceleration process involving retropropulsion in a supersonic airflow environment. I know that previous ...
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2answers
715 views

How great is the stress on a rocket at max-q [closed]

How much more stress does a rocket experience during max-q compared to other parts of the flight (such as when it is at rest on the pad)? Use data for any 'cylindrical' rocket if a specific example ...
5
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1answer
497 views

Why are the cells on grid fins square in shape?

What is the reason for the square shape of the cells on grid fins such as those on the Falcon 9 landed by SpaceX, on missiles, or other places?
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2answers
1k views

What happens if the Falcon 9 launches with its grid fins open?

Let's suppose that the grid fins of the Falcon 9 remain open and the rocket still launches. This is probably never going to happen because the SpaceX team is exceptionally good, but I am trying to see ...
6
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1answer
346 views

Upper stage structural loads on ascent?

In another question, this came up: For example, if a Falcon 9 launches 20 tons of fuel to dock in LEO, how can the same upper stage be used to launch 40 tons of fuel to the same orbit? Doesn't it ...
9
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1answer
687 views

Just how much can tall skinny rockets bend? (roughly, safely)

Below is a GIF I prepared and used in an earlier question, and the answer seems quite reasonable. With a height to diameter ratio of about 70 m to 3.7 m (nearly 20:1) a weight-conscious design, ...
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1answer
2k views

What are these tiny triangular fins on the Soyuz launcher?

What are the small triangular fins on the lowest part of the boosters of the Soyuz 2.1 rocket? What function do they have? I circled one of them in the upper image here. They are not visible in the ...
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2answers
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Booster rocket free way of achieving orbit?

https://worldbuilding.stackexchange.com/questions/104593/can-you-get-an-orbital-mass-driver-to-work-this-way-to-propel-in-space-without Using balloons to carry a blimp or suspend an electric rail ...
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0answers
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Max Q vs Prandtl-Meyer Fan

Does Max Q occur before or after the Prandtl–Meyer expansion fan? The shape, nature's way of avoiding a single shock wave (per Wikipedia) is visible on the Apollo launches for example. Apollo 11, ...
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1answer
540 views

Purpose of hemisphere under shuttle nose cone (Enterprise)

I noticed a small hemisphere protruding from the dorsal side of the Enterprise space shuttle's nose cone, forward of the front landing gear. I have no clue what its purpose is but am far from an ...
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1answer
1k views

Angle of attack, or displacement angle?

When I hear "angle of attack" or AoA, I think of an airplane. Usually, both the airfoil and the plane itself have a clearly defined 'top' and 'bottom'. In this case, the concept of angle of attack is ...
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1answer
3k views

What's the atmospheric drag coefficient of a Falcon 9 at launch (sub-sonic, large fairing)

While I said just a few hours ago that "There's almost no such thing as a dumb question! this one just might sound like one. I'm making some slides about first principles thinking applied to ...
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2answers
2k views

How long does Max-Q last?

When watching rocket launches, the commentary or status reports often mention that the vehicle is "passing through Max-Q" - how long does the "passing" take? Is the event instantaneous or is there ...
6
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1answer
225 views

Is the Dragon Mono-Stable?

Re-entry vehicles tend to be either mono-stable (eg soyuz) or bi-stable (apollo) which refers to the orientations in which they're aerodynamically stable. In at least one case, this has proved very ...
0
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1answer
327 views

SpaceX hovering rocket? [duplicate]

How does SpaceX get their rockets to stay vertical when hovering without tips over and eventually crashing into the ground? I don't mean the initial launch. I mean when its coming back down I feel ...
4
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1answer
361 views

Is Martian wind strong enough to produce aerodynamic forces on a spacecraft?

If a spacecraft is entering the Martian atmosphere (say Curiosity rover in a Sky Crane capsule), is the wind strong enough to actually produce forces on the spacecraft? (like you would see during an ...
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3answers
1k views

Why doesn't the Falcon 9 booster use rigid air brakes during landing attempts?

SpaceX's attempts to land involve using the first stage engines to slow the booster down, and use grid fins to perform trajectory adjustments. Parachutes generally aren't rigid and can throw the ...
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1answer
565 views

Why are the nose cones of current spacecraft less pointy?

You would think that with the quest for aerodynamic efficiency in current spacecraft that the nose-cones at the pointy end of the launch-vehicle would have a sharp taper, more so for craft that aren't ...
3
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1answer
97 views

Feathering Profile Change for Virgin/TSC/Spaceship Two

We know that the Spaceship One and Spaceship Two designs from Virgin Galactic/The Spaceship Company/Scaled Composites employ feathering for aerobraking and maneuverability. I can't seem to track down ...
19
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4answers
937 views

Gliding into the atmosphere

The recent question about Cessna reentering from ISS got the answers that all imply a rapid drop. But from what I know, air drag is proportional: to square of airspeed to air density to attack ...
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4answers
2k views

Reason for different “cone angles” of different space capsules?

Here is the Cargo Dragon: And here is the Orion: The "cone" that orion makes has a large opening angle - perhaps about 70 degrees. Meanwhile, the Dragon is almost cylindrical - the opening angle is ...
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2answers
2k views

Why is Dragon the only spacecraft that is currently in use to not need a fairing for launch?

Dragon is the only spacecraft I know of currently in use that doesn't need a fairing for launch on top of a rocket. I know there are others in development or in testing like Dragon v2 and CST-100(not ...
18
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1answer
2k views

What control engineering techniques are used for the landing maneuvers of Falcon 9-R?

Which are the main control theories behind the landing maneuvers of the Falcon 9? For the hovering part, as it approaches the landing surface, I guess the inverted pendulum control approaches would do ...
7
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2answers
5k views

Optimal speed per altitude for orbit launch

On Kerbin, rockets have an optimal speed depending on altitude for maximum fuel efficiency, as You can save fuel by being close to your terminal velocity during ascent. Lower velocity wastes delta-...