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.

Filter by
Sorted by
Tagged with
24
votes
2answers
4k views

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 ...
24
votes
2answers
4k views

Golfball Dimples on spaceships (and planes)?

The best of us get stupid ideas which run through our heads day in and day out without finding an answer. That's why I came here: A golf ball has dimples to reduce drag and increase flight distance (...
23
votes
5answers
2k 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 ...
20
votes
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 ...
20
votes
4answers
3k 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 ...
19
votes
4answers
6k views

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 ...
19
votes
1answer
6k 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 ...
18
votes
1answer
3k 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 ...
17
votes
3answers
8k 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 ...
16
votes
4answers
5k views

Is this egg-shaped nose cone a good, aerodynamic design?

So Jeff Bezos has recently travelled to space aboard an Amazon-funded rocket, which has an unusual, egg-shaped nose. However, just about every other rocket I've seen has more of a cone-shaped nose, ...
15
votes
1answer
1k views

Soyuz Steering during Re-Entry

In this youtube video, it talks about steering Soyuz by changing lift. Why does roll rotation help in changing lift and also helping in cross range steering? I am looking for an answer from ...
15
votes
1answer
817 views

Is Starship aerodynamically stable when travelling nose first?

Is Starship aerodynamically stable when traveling nose first, or does it require constant gimbaling from the main engines to keep it pointing nose first? Is this part of the explanation for why Space ...
14
votes
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 ...
13
votes
3answers
4k 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 ...
13
votes
1answer
887 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 ...
12
votes
2answers
3k 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 ...
12
votes
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 ...
11
votes
4answers
3k views

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 ...
11
votes
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 ...
10
votes
2answers
4k 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 ...
10
votes
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 ...
10
votes
2answers
475 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
votes
2answers
1k views

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 ...
9
votes
1answer
2k views

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 ...
9
votes
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-...
9
votes
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 ...
9
votes
1answer
988 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, ...
8
votes
3answers
2k 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 ...
8
votes
3answers
376 views

Might Ingenuity tip over?

While Ingenuity patiently waits for its preflight checks to pass, how likely is it that a wind gust could tip it over? How strong and how rare a gust? Those rotors have plenty of area. (Surely NASA ...
8
votes
2answers
380 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-...
8
votes
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 ...
8
votes
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 ...
8
votes
0answers
124 views

How heavy were Perseverance's balance masses?

Perseverance ejected two 70 kg "cruise balance masses" just before it became an airplane, to move its center of mass off axis and increase its angle of attack from 0° to about 16° to make it ...
7
votes
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 ...
7
votes
3answers
520 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 ...
7
votes
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 ...
7
votes
1answer
183 views

How hot do the nose cones of fairings actually get on ascent?

I've been reading into aerodynamic heating of rockets, and it's seemingly a rather complicated topic. It's relatively easy to calculate the stagnation temperature at a given mach number, and that is ...
6
votes
3answers
1k views

Is there a mathematical formula to calculate drag force without empirical testing?

Typically people put the interested rocket prototype in a wind tunnel to find out the drag force and use the drag force equation to calculate the drag coefficient of the rocket model. I am wondering ...
6
votes
1answer
1k views

What is the terminal velocity of SpaceX Starship?

What is the terminal velocity of starship on earth and mars during descent? Has SpaceX revealed or hinted the values of projected surface area and drag coefficient of the vehicle?
6
votes
2answers
425 views

What was the actual Q-alpha limit for Saturn/Apollo launches, and what was the typical max Q-alpha?

Organic Marble's answer to a previous question about Apollo abort limits clarified that the figure of concern was the product of dynamic pressure (Q) and angle of attack (alpha), with the 100% level ...
6
votes
1answer
287 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 ...
6
votes
1answer
125 views

What benefit do the aerodynamic stabilization "pods" on the PSLV-CA provide?

Whilst writing this answer about the PSLV, on this informative page about its Secondary Injection Thrust Vector Control system, this image (cropped) is displayed, showing that for the Core Alone ...
6
votes
1answer
196 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
votes
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. ...
6
votes
1answer
678 views

The aerodynamic stability of the truncated cone shape

Can someone explicate the stability of the truncated cone shape of the reentry vehicle of a spaceship when moving in the atmosphere with its bottom facing forward? It seems counterintuitive that it ...
6
votes
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 ...
5
votes
3answers
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 ...
5
votes
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 (...
5
votes
1answer
182 views

How to fit, into a cubesat, 29 trackable high drag subsatellites with well-defined aerodynamic profiles

Johnathan McDowell's recent tweet says: The @AerospaceCorp Aerocube-10a cubesat carries 29 small passive high-drag subsatellites used to probe the density of the upper atmosphere. 3 have been ejected ...
5
votes
1answer
648 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 ...