# Tag Info

One of the keys to SpaceX's cost advantage is standardization on common parts. One example is the Merlin engine, which is used on both the first and second stages of the Falcon 9 and Falcon Heavy (though a slightly different vacum optimized version on the second stages). This is also done for fairings. Fairings are very expensive to make (around $6M). ... 48 Aerospike nosecones have a couple of big benefits which, to fully appreciate, I'd need to give a little background on. At the risk of dating myself, "Sherman, set the WABAC machine to the 1950s": The United States had a problem. It was trying to develop a missile with a range of 1,000 miles based on the work of Wernher von Braun and a number of other ... 38 Surely, a passive trailing end of an aerodynamic body should optimally be more of a "tip". A classic example: space shuttle transported by airplane would get a "tail cone" over the engines to reduce the drag: Keyword being passive. Compare to a fighter jet: The drag at the trailing end would be caused by vacuum/underpressure left in the wake of the passive ... 29 By itself the roll doesn't generate lift. But the Soyuz descent module (DM) enters with a non-axial center of mass that results in a non-zero angle of attack, and hence some lift. Several spacecraft, including the Apollo Command Module, have used this offset-mass approach to generate lift, thus achieving some measure of control over the atmospheric flight ... 29 The dimples on a golfball is structurally the simplest iteration of a vortex generator. Vortex generators are most definitely used in practice to improve aircraft performance. (for some usage examples, see the tag over at Aviation.SE) Turbulence will happen, that's the fundamental nature of aerodynamics. Controlling the transition into turbulence is the ... 28 The only satellite I know of that was shaped to have low drag was GOCE, which orbited at 250 km. Since it was vital to ensure that the measurements taken are of true gravity and not influenced by any movement of the satellite, this unique five-metre long arrow-shaped satellite had none of the moving parts often seen in other spacecraft. The satellite, ... 25 The ISS solar array masts are launched collapsed in canisters, and run through a deployer mechanism to erect them as a long straight object. I see no technical reason why a much longer mast couldn't use this system. For details see this question and answer: How do the booms on ISS (and other spacecraft) extend and retract? 23 Long rigid structure can be transported as raw material for fabrication in space, in the same way that continuous rain gutters are made. In the pictures below, you can see a machine that creates the rigid rain gutter from a compact roll of sheet metal. The method is provides for compact transportation, only limited by the compacted size and weight of the ... 22 I want to focus on aerodynamic stress however, like when a rocket deviates from its path or has a wrong angle of attack, what causes it to be destroyed? In many cases, it's not aerodynamic stress. Many launch vehicle explosions result because they are commanded to do so. Every launch vehicle launched from the U.S., including the solid rocket boosters on ... 21 You'll notice it is used on submarine launched ICBMs. Blunt noses are very efficient for the missile to get out of water (and are shorter than long, profiled ones, which helps with submarine diameter), but aren't great in atmosphere; hence the deployable aerospike to make them efficient in both media. 17 The Soyuz (booster) User's Manual from Arianespace calls them "aerofins" and says they are part of the attitude control system. An additional image I ran across showing the aerofins and stating that they are for "auxiliary course correction in the atmosphere". 17 "Maximum Q" is technically instantaneous, but less formally it can refer to a period of time where pressures are nearly at maximum. Here's a graph of dynamic pressure for a simulation of the Saturn V; (gone missing; archive.org link) most launchers will have an essentially similar curve. You can see that it peaks close to 34kPa, but it's above 95% of that ... 17 Best way to do this could be to research, develop and send a "3D tube printer satellite" to low Earth orbit, and feed it with whatever material in liquid, powder or filament form, which will not require any special attachement or design modification to existing rockets, since it can fill any shape of a given volume. For instance one 0.5 km long tube, 10 cm ... 16 Dragon is not the first manned spacecraft to launch without a fairing Mercury had a Launch Escape Tower bolted to the top. Gemini had ejection seats so no tower was needed Starting with Apollo, a small fairing cover was included as part of the LES. This cover detached with the LES during flight to reduce weight. With Soyuz all capsules have had a fairing ... 14 The dimpled sphere may produce lower drag (though as Uwe points out I’m not sure if that is true in hypersonic flight). However, this does not mean that it will be better at surviving reentry. Higher drag implies a faster reentry and shorter exposure to extreme temperatures. Conducting heat to the core takes time, so even if the outer layer is ablating, the ... 14 Could a slower or smaller rocket take advantage of lift if all the stages had wings? Wings on the first stage can be useful; the Pegasus air-launched rocket has wings on its first stage that provide some lift. In most cases wings aren't worth using on orbital launchers; they add drag and weight that usually isn't compensated for by lift. Wings on upper ... 13 As the other answers say, the actual peak of dynamic pressure is an instaneous point, but actions taken around this time are often described in terms of Max Q. For example, Space Shuttles would throttle down their main engines for 30 seconds or so while Q peaked. (The SRB propellant grain was also shaped to lower thrust during this time, but that was ... 13 Getting rid of the nose cones would make things worse, not better. The reason the nose cones allow less control than the typical F9 (or FH center core) is because the cylinder of the rocket usually continues well above the grid fins. The interstage (which extends above the grid fins, and does not separate from the first stage at any point) is the same width ... 12 It most certainly won't hurt anything. From FAA's document on returning from space, there is a very interesting chart, which I've included below. So the maximum g load is almost always at around 4500 m, for this particular flight trajectory. From other charts, we find that a lower angle will spread out the re-entry forces, and specifically make the max ... 12 They needed to upgrade the grid fins anyway, this is one of the modifications intended for Block 5. So the new grid fins were available. This meant the choice is between: switching to more expensive (but reusable) grid fins, or throwing away the nose cones, and adding another separation event, making sure the nose cone doesn't hit the stage after ... 12 You need aerodynamic front to let the air flow around the rocket in supersonic speeds. But in the bottom the air does not flow around it: it's the place where engines are placed, and escaping exhaust gas makes the bottom aerodynamic enough. Take a look at the Falcon 9 rocket in flight: (image taken from http://spacenews.com/spacex-shuffles-launch-schedule-... 11 As usual in this sort of thing, there's no single optimal answer because the capsule has to do a few different things, so the shape has to balance different requirements. A narrow cone angle gives less drag on ascent. A large broad base is required for deceleration on re-entry. A squat cylinder gives more convenient usable interior space. I believe the ... 11 That's an easy one.... S Band Antenna..... This image comes from the document JSC-13864 SPACE SHUTTLE ORBITER APPROACH AND LANDING TEST FINAL EVALUATION REPORT. It is on page 134 of the pdf. Here is a close up picture of the antenna, from here... 11 The ideal aerodynamic shape for drag purposes is indeed tapered at the back, but that sort of boat-tailing is very detrimental to aerodynamic stability. With a tapered tail, if the rocket body starts to turn out of the airstream, there's little corrective force at the back end -- the tail doesn't extend into the airstream until the departure angle equals ... 11 A thin pole .5 km long is easier said than done. A scaffolding pole (4 m long, 4 cm diameter) may seem rigid, but link a few end-to-end and the resulting pole will be flexible. If you attach it to the outside of a rocket, it'll start wobbling under the aerodynamic loads. You can combat this by making the diameter larger, but to support a pole 500 m long ... 11 When you're in orbit you have velocity roughly parallel to the atmosphere, a flat-ish shape angled properly can "fly" across it in a lifting entry where you can dissipate energy in the thinner upper atmosphere before you hit thicker atmosphere. The first stage of a rocket uses most of its energy to gain altitude, getting above the thickest part of the ... 11 As rockets get larger, the importance of drag relative to mass decreases (drag runs generally proportional to cross section and surface area while mass runs generally proportional to volume). Hence big rockets tend to have less pointy payload fairings, which provide more useful volume by mass, as Hobbes' answer shows. Qu8k was a small rocket developed with ... 10 It seems that they initially planned to use the landing legs as air brakes. Elon Musk stated that: If you then do some interesting things, like look at our landing gear, they're essentially like giant body flaps, so the drag - when we deploy the landing gear, the drag massively increases, so we have dual use of the landing gear as giant body ... 10 If the optimal speed is terminal velocity, this is the formula you need:$V_t= \sqrt{\frac{2mg}{\rho A C_d }}$where -$V_t$is terminal velocity, -$m$is the mass of the falling object, -$g$is the Earth's gravity|acceleration due to gravity, -$C_d$is the drag coefficient, -$\rho\$ is the density of the fluid through which the object is falling, ...