Hello All,

SpaceX is also planning to recover the Falcon 9 payload fairing halves for reuse, which will save still more money, beyond what first stage recovery and reuse will save. The fairing recovery method is shown here (see: http://imgur.com/Otj4QCN [I've also attached this diagram below]). It was also discussed in this CRS-8 post-launch press conference (see: http://spaceflightnow.com/2016/04/0...ch-and-landing/ ). In this press conference, Elon Musk also described the ASDS deck tilt limits for successful landings (plus he said that the stage landed in ~50 mph winds yesterday!), as well as the ASDS stage securing and handling procedures and SpaceX's future plans.

Attached Thumbnails

 

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I would really have to wonder if it were economically feasible to recover and reuse the fairings. It seems to me you're adding a lot of cost and especially weight for the part itself due to it having to be beefed up structurally. Add to that mid air helicopter recovery expenses and the total cost of fairing recovery increases.

I wonder if this is mostly a "feel good" ploy to appease eco-nuts.

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That's a good question. I think full and rapid reusability is a passion of Elon Musk's (he was disappointed when their planned second stage recovery proved to exact too large a mass penalty to be practical), although pleasing the greenies is a nice side benefit. Also:

Those big Falcon 9 fairings do cost several million dollars apiece, and their re-entry velocities are pretty low, so the fairing halves may not require much modification (and few additions) in order to be recoverable and reusable. (Other payload fairing halves have been found relatively intact in the ocean, and a foam Centaur stage insulation stave from an old Atlas-Centaur launch [they were pretty fragile] was found intact, floating in the Atlantic.) In addition:

There were proposals to recover rocket stages via the same helicopter-snagged parachute method that SpaceX is working on for recovering the Falcon fairings. McDonnell Douglas found that such retrieval of Saturn S-IVB stages (equipped with lightweight heat shields--they would have slowed down quickly) from orbit was feasible, and there was even a proposal to recover Saturn V S-IC first stages in this way, using a very large, rotor tip-burner powered helicopter. These options weren't pursued after it became clear that few Saturn IB and Saturn V vehicles would be flown. The Falcon 1's first stages could have been recovered in this way, using an existing helicopter, and so could Firefly Space Systems' www.fireflyspace.com smallsat launchers' first stages and strap-on boosters.

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NAR #54895 SR

Also remember that the fairings already have to be pretty structurally strong. Not sure what the max-q (maximum dynamic pressure) of the typical Falcon 9 launch is, or what the factor of safety in the design is (NASA is 140% of anticipated load) but for most vehicles max-q can run around 400-600 psf (pounds per square foot), with some vehicles experiencing max-q pressures up to 800-1000 psf, some even more (but usually they tweak the design to keep it as low as realistically possible. 400 psf is like the weight of two 200 pound linebackers standing on a 1 foot square paving stone. Imagine having that much weight on your chest. Consider then the number of square feet of surface area on such a fairing which may be several meters in diameter and maybe 10 or so meters long, or longer, which adds up to a LOT of square feet of surface area, and the forces are pretty immense. While they're moving at a pretty good clip (speed of the second stage when they're ejected, basically), they have a lot of surface area and not a huge amount of mass, so after tumbling through the near-vacuum at altitude (90% of Earth's atmosphere is below 20 miles high) despite moving at a good clip they decelerate fairly quickly in even thin air as they fall, making for a longer but lower temperature heat pulse during reentry. It's not like they come screaming back into the dense lower atmosphere at stupid-high velocities, which tends impose huge loads on stuff and makes it blazing hot in a short, very intense heat pulse. Plus, fairings are designed to handle certain heat loads-- I remember reading that the shuttle ET nose heated to around 400 degrees or so during the shuttle's ascent through the upper atmosphere from friction drag. Payload fairings would, depending on the speed and trajectory and acceleration of the rocket vehicle, experience broadly similar heating during ascent.

Because they're a large surface area and relatively lightweight for their size, if they can be weighted to create a "natural stability" (which the parachute package can be conveniently used as stability ballast during the reentry part, and using the air flow's natural dynamics (CG/CP relationship) to stabilize the fairing (like a surfboard or "lifting body" reentry vehicle, so we're not talking "new technology" here... Heck ALL our US spacecraft have had certain levels of "natural stability" in that the CP was behind the CG of the capsule in the proper orientation for reentry and landing-- once the capsule hits the air and starts to decelerate, the force of the air turns the capsule naturally "right side up", which is to say, "heavy side down". The Russians weren't confident in this so they designed their early capsules as spheres with heat shielding all the way around, so no matter which way it entered it was safe. Once they found that they DO naturally turn "heavy side down", they designed the Soyuz capsule with it's famous "headlight shape"). Once you've got your payload fairing halves entering the lower atmosphere stably, then you can deploy your chutes to slow them down and, by the looks of it, put them in a glide that can then be snagged in midair by helicopters.

This idea is nothing new either. Not only was blackshire's comments about possible recovery of Saturn stages correct, but it goes back even further than that. The Corona spysat film buckets that were ejected from the satellite and reentered the atmosphere in a specific location, descended by parachute which were then snagged in midair by C-119 Flying Boxcars, which then reeled in the snagged parachute and film bucket into the back of the aircraft. This was done due to the fear that the top secret film might be suddenly "snagged" from an ocean splashdown by a Soviet submarine BEFORE US recovery forces could retrieve it from the drink, and with the film in their possession they could easily "reverse engineer" the capabilities of the camera systems on the spy sats. Also, NASA has designed some probes to recover sample canisters in reentry vehicles floating under parachutes that were then snagged out of midair by helicopter for a safe and gentle landing, like the Stardust mission, and Genesis mission (which due to a deceleration sensor being installed upside down never deployed its parachute and crashed, but was largely recovered later).

Anyway, it's an interesting idea... and if it works and saves a few million bucks a shot, well, I'd say that's well worth the effort.

Later! OL J R

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I concur--for recovering the Falcon 9 payload fairing halves (in scale models as well as the full-scale vehicles), placing the ballast (such as the parachutes) where the keel would go in a canoe would cause each fairing half to descend as such a ballasted canoe would if dropped from a plane, gently rocking about its axes but stable. And:

MDAC's (McDonnell Douglas Astronautics Corporation's) S-IVB stage recovery study showed the same happy circumstances, because a nearly-empty S-IVB would quickly slow down during re-entry [from *orbit*!] due to its low ballistic coefficient (low mass per frontal area), thus avoiding a long, hot heat pulse. MDAC engineer Philip Bono used this effect to full advantage in his SSTO spaceship designs (one of which was actually a modified S-IVB with an aerospike engine and landing legs, called SASSTO)--Philip Bono's and Kenneth Gatland's book "Frontiers of Space" covers all of his recoverable S-IVB and SSTO designs in considerable detail. Also:

The now-defunct t/Space (Transformational Space Corporation, see: https://www.google.com/#q=transform...ace+corporation ) planned to fly a simple two-stage, air-launched, pressure-fed LOX/propane launch vehicle called QuickReach for orbiting satellites and astronauts, and reducing the ascent dynamic pressure loads was one reason why they chose air-launching. Their Crew Transfer Vehicle, or CXV as it was called for short, was also simple; being an enlarged version of the blunt-cone “bucket”-type re-entry vehicles used in the Discoverer, CORONA, and Biosatellite programs, it was self-stabilizing during re-entry. Although it was to have been equipped with thrusters, it was designed to self-align itself via aerodynamic forces and re-enter safely even if all of its attitude thrusters were disabled. It also had room on its wide, flat rear face for a docking port and deployable and (for re-entry) re-stowable solar arrays. In addition:

A smaller, self-stabilizing re-entry vehicle of this very same type, about the size of the spy satellite film return “bucket” RVs, was proposed for the reusable CHEOPS (Cyclically Harvested Earth Orbital Production System, see: https://www.google.com/#q=CHEOPS+Cy... ction+System), which would return microgravity-produced products to their owners from orbit, via steerable parafoil after re-entry. The CHEOPS vehicles were designed to fly as either "space available" secondary payloads or as primary payloads. This is one of those timeless ideas that will likely be economically viable no matter how advanced reusable launch vehicles become, because the CHEOPS vehicles are so simple and would provide for private (proprietary) microgravity industrial and medical research. (Arthur C. Clarke also wrote that developing such a standard "cargo nose cone," as he called it [he had a larger one of the same shape in mind] would enable a "lunatron" electromagnetic launcher on the Moon to send lunar-made products to Earth more cheaply than cargo aircraft can transport the same masses on Earth! Using PICA-X, such RVs could fly many times before requiring new heat shields.)

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NAR #54895 SR

Remember too that the ORIGINAL space shuttle design, the Faget stubby-winged spaceplane flying on the fully-reusable flyback booster, was going to be 'fluffy' enough (low weight vs. surface area ratio) to reenter without the extreme heat pulse that necessitated a heavy heatshield. It was going to use "hot structures" (high temperature metallic shingles over an aero-elastic structure designed to handle the heat) for reentry, with no need for a traditional heat shield common to much "denser" spacecraft up to that time. (with high weight vs. surface area ratios). In short, since it carried its large hydrogen fuel tanks internally, which were very large, and which were empty at reentry and therefore very light, the vehicle "recovered like a feather" and slowed down rather quickly while still in the very tenuous upper reaches of the outer atmosphere on reentry, lowering the heat pulse maximum temperature to within acceptable limits for a metallic-type hot structures heat shield method and materials.

When the shuttle was enlarged for the Air Force requirements and forced to switch to delta wings for the "once-around" polar orbital missions the Air Force mission requirements spelled out (which were never done anyway) the mass of the vehicle increased at the same time the surface area decreased (due to switching to a non-fully reusable vehicle design with a throw-away External Tank for the hydrogen and oxygen propellants) and so the heat pulse loads during reentry increased to the point that a metallic hot structures heat shield system was no longer adequate-- thus the move to a "reusable" heat shield in the form of heavy, brittle heat tiles glued to the belly of the orbiter.

Later! OL J R

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GEEZ what [edit-retype] silliness.

Those fairings cost about $4-5 million total, which is a big percentage for a $70 million launch.

That's the "easiest" next step for saving costs, after being able to recover and re-use the first stage. The added mass would tend to mainly be the parachute system. For most missions it'd be far more than worth its weight, other than ones with very heavy payloads that push the margins.

- George Gassaway

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Yep, panels or shingles of René 41 (which was used on the sides of the Mercury and Gemini capsules) would have sufficed for covering most of Dr. Maxime Faget's straight-winged, low-crossrange DC-3 orbiter's surface (see: https://en.wikipedia.org/wiki/North_American_DC-3 , http://web.archive.org/web/20120316...elvs/sld022.htm , http://www.pmview.com/spaceodysseyt...elvs/sld029.htm , and http://forum.nasaspaceflight.com/index.php?topic=9004.0 ). I still think it would be a viable--and even more practical, with today's more advanced technology--spacecraft design, because it's a space-adapted airplane rather than a winged spacecraft (the DC-3 orbiter--and its later, larger Phase B design study straight-winged variants--were capable of self-ferrying using internal or bolted-on [in pods] turbofan engines, due to these orbiter designs' low wing loading); their straight-winged boosters also had this self-ferrying capability. Also:

Before NASA (for economic reasons, hoping to satisfy the USAF's requirements that ultimately forced them to adopt the delta configuration and a large payload mass) "super-sized" the Faget orbiter design (which made *all* subsequent orbiter designs--straight-winged as well as delta-winged--more expensive), NASA's favored, smaller versions of it were eminently feasible (as were their smaller straight-winged boosters, which would have self-ferried back to the Cape after landing downrange). A modest Faget-type Shuttle using a kerolox (or LOX/methane) straight-winged booster with a LOX/LH2 straight-winged orbiter could be built today, and several existing rocket engines and turbofan engines could power both stages. In addition:

Max Faget said that his straight-winged orbiter's upward-curved (from the middle, up toward the nose and tail, as viewed from the side) fuselage underside, and its wings' dihedral, made it effectively "an airplane-shaped plan view (as viewed from above) cut out of an Apollo capsule's spherical-section heat shield." In 1969, he built a balsa-and-tissue model of his straight-winged orbiter design and demonstrated its passive re-entry stability by dropping it from a raised platform in a building at the Johnson Space Center. The little orbiter model dropped straight down slowly and stably, in a wings-level (and fuselage-level) attitude. It also glided well when tossed forward. In 1970, a larger (12' long, if memory serves) fiberglass model of his DC-3 orbiter, which was equipped with attitude thrusters, was drop-tested from a Sikorsky Skycrane helicopter several times. It demonstrated the passively stable "belly first" re-entry attitude, and it also successfully transitioned to normal forward-gliding flight. The model (which had no landing gear, for the sake of simplicity and lower cost) was recovered by parachute at the end of each test flight (I got photos of this model from JSC, and Dennis R. Jenkins reproduced them in the third edition of his book "Space Shuttle: The History of the National Space Transportation System--The First 100 Missions" [see: http://www.amazon.com/Space-Shuttle...s/dp/0963397451 - AbeBooks.com booksellers have it, too: http://www.abebooks.com/servlet/Sea...st+100+Missions ]).

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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
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NAR #54895 SR