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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12
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3answers
2k views

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 ...
13
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3answers
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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 ...
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5answers
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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 ...
9
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1answer
989 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, ...
17
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3answers
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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 ...
7
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2answers
704 views

How does the dynamic pressure evolve during reentry?

During launcher ascent, dynamic pressure evolution is described in this answer for the Saturn V. I suppose this is similar for most launchers. Given the protections designed for reentry, I suppose ...
20
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4answers
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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 ...
8
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1answer
2k 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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3answers
954 views

Would a balloon pop if dropped from space?

Could a "simple" inflated party balloon be dropped from space entering an atmosphere? The first case at orbital speed, the second case just outside the atmosphere and the third interplanetary? The ...
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2answers
610 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 ...
7
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1answer
499 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 ...
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4answers
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Just how pointy does a rocket's nosecone need to be?

There are some beautiful images of the Qu8k rocket launch on this web page and I show a few below. There's a video (below) and the PDF Qu8k Final By Derek Deville, November 27, 2011 The stainless ...
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1answer
289 views

How high could a weather balloon be used on Mars without rupturing? [duplicate]

What is the maximum height could a weather balloon achieve on Mars without rupturing? Assume that the balloon is adapted for Mars' atmosphere and gravity from standard high altitude balloons used on ...
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1answer
177 views

What is Direct Simulation Monte Carlo and why is it a good method for simulating spacecraft drag in VLEO?

Reducing spacecraft drag in Very Low Earth Orbit through shape optimisation J. A. Walsh and L. Berthoud (2017) show simulations calculating drag coefficients for different "nose cone" shapes ...
9
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1answer
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What is the most aerodynamic Satellite?

From what I understand at least in the lower orbits you want the least amount of drag possible. My brain is telling me that a long pole or submarine shape satellite orientated to the direction of ...
20
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8answers
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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 ...
9
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2answers
9k 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-...
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5answers
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Could rockets launched from the ground use wings in the stages?

Could a slower or smaller rocket take advantage of lift if all the stages had wings? Could the stages reduce splashdown impact forces by using a spinning seedpod-like design (as shown in the image ...
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1answer
3k 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 ...
5
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1answer
692 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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3answers
307 views

Can more thrust come from launching parallel to water?

Would having the exhaust of a rocket or air breathing engine in an early stage in close proximity to water on a horizontal launch provide more thrust? Could a rocket launch off water horizontally in ...
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2answers
337 views

Can it be calculated that near the Kármán line 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
631 views

Can a reusable electric powered blimp stage for launch possible?

Originally this question asked about using blimps and electricity in replacement of boosters. As written then it was no good and got down votes. I had a few question marks and each question really ...
10
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1answer
691 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 ...
11
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1answer
943 views

Testing flight characteristics before actual flight in model rockets?

I do a lot of scratch design/building of model rockets, but one of the things that I've struggled with is testing the models I come up with. Some of them are purely intended to be static display ...
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2answers
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How do we control a Reentering Capsule in the denser part of the atmosphere?

My question is: How do we control a Reentering Capsule in the denser part of the atmosphere? How does the aerodynamics of the Reentry vehicle workout? In other words, how does a reentry module ...
5
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2answers
447 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 (...
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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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2answers
477 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 ...
9
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1answer
452 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 ...
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1answer
6k 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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0answers
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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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2answers
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What are the pros and cons of Aerospike nosecones?

Some rockets, mainly (only?) ICBMs have Aerospike nosecones Why are they preferred in lieu of traditional nose cones? Illustrations: An aerospike nosecone on a trident ICBM Video including the ...
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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 ...
14
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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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1answer
618 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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0answers
1k 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 ...
6
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1answer
197 views

How to calculate the lowest possible altitude a satellite can orbit at due to aerodynamic heating if provided with a sufficient propulsion system?

If a satellite is equipped with a propulsion system which is enough for compensating the local drag and maintaining the orbit, then aerodynamic heating would be the limiting factor for attaining the ...
6
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2answers
333 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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3answers
623 views

Would a standard gravity turn still be the most optimal path to orbit if Earth did not have an atmosphere?

If Earth had no atmosphere, then would a standard gravity turn still be the most optimal path to orbit? Why or why not?
5
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1answer
651 views

Why was the nose cone on the Space Shuttle's external tank pointy?

Inspired by comments under this answer to this question Just how pointy does a rocket's nosecone need to be? (see also Why are the nose cones of current spacecraft less pointy?) Why was the ...
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0answers
121 views

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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3answers
104 views

Changes in Orbital Parameters Due to Drag

Other than STK, are there any commercially software packages available to model changes in orbital parameters due to increases/decreases in satellite drag. I am trying to figure out if aerodynamic ...
3
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1answer
2k views

What is the terminal velocity on Mars?

How would I calculate the terminal velocity of Mars? What is the terminal velocity of a balloon entering Mars' atmosphere? Would a balloon pop if dropped from space?
3
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2answers
278 views

Number of segment in Wing leading Edges

Can anyone highlight the basis of having 22 NO’s of segment in wing leading edges of space shuttle.
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0answers
140 views

Is there a calculator or set of formulas for estimating 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
2k 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 ...
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2answers
117 views

Could the $C_L$ of the X-15 be calculated from the flight data near the Kármán line altitude?

The "lift coefficient" $C_L$ can be very different for one specific aircraft at different speeds. According to this article from NASA about the lift coefficient: So it is completely incorrect to ...
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1answer
121 views

Is it correct to apply the vis-viva equation to an airplane that flies in a straight line at the Kármán line?

The vis-viva equation models the motion of an orbiting body and it applies when the only force acting on the body is it's own weight. So is it correct to apply this equation to an airplane that ...
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1answer
235 views

Where does the definition of the Kármán line on Wikipedia come from?

According to Wikipedia's article about the Kármán line: The Kármán line is the altitude where the speed necessary to aerodynamically support the airplane's full weight equals orbital velocity ( ...