The LOFTID inflatable aeroshell was apparently a complete success, inflating in space, entering, popping a chute, splashing down and being recovered at sea.
I wonder if this could be conveniently applied to the Falcon 9 second stage.
Nov 112022
Nov 102022
Atlas launch to test inflatable heat shield
A United Launch Alliance Atlas 5 is scheduled to lift off from Vandenberg Space Force Base in California at 4:25 a.m. Eastern Nov. 10. The primary payload of the rocket is the Joint Polar Satellite System (JPSS) 2 weather satellite …
A secondary payload on the launch of JPSS-2 is Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID), a NASA technology demonstration. While JPSS-2 will be deployed nearly a half-hour after liftoff, LOFTID will remain attached to the Centaur until 75 minutes after liftoff, following a deorbit burn of the Centaur.
Shortly before deployment, LOFTID will inflate a reentry shield six meters in diameter. That heat shield will slow down the vehicle from orbital velocity to Mach 0.7 as instruments on board collect data on the performance of the shield. LOFTID will then deploy parachutes to slow it down for the rest of its descent, splashing down in the Pacific east of Hawaii to be recovered by a ship.
Inflatable heat shields have been studied since before humans flew into space. Normal heat shields need to withstand insanely high temperatures, requiring materials that are either insanely expensive and complex, or that involve complex, fragile and heavy active cooling systems (such as water cooling through transpiration), or which are ablative. The latter variety is technologically fairly simple, but ablatives tend to be heavy and they are labor intensive to apply and make reusability difficult.
With temperatures reaching several thousand degrees, inflatable materials would seem inappropriate for heat shields. But those high temperatures are not a mandatory feature of re-entry. To a first hand-wave approximation, the maximum temperature is proportional to the mass-per-surface-area of the re-entry vehicle. A one-ton vehicle is going to have to shed all of its orbital velocity, converting all that kinetic energy into thermal, regardless of the size or shape or cross-sectional area. The way that is done is by compressing the air the vehicle slams into; the heating isn’t due to friction, but to the compression of the gas. If you can spread that heating energy out wider… the gas doesn’t heat up as much per unit surface area. Heating can be reduced from the sort of thing that will melt tungsten to the sort of thing that can be survived by advanced polymer fibers. As a bonus, the inflatable shield, being far larger than the solid shield on the vehicle, provides drag all the way down. In principle it would be possible to dispense with parachutes, wings, retro-rockets, and simply drift down using the shield as an inverted parachute. This was the case for the Douglas “PARACONE” concept from the mid-1960s, designed for, among other uses, as an emergency “life boat” for astronauts in space. It would provide for a safe entry, deceleration and touchdown on either land or water.
Nov 092022
A video tour of the Hughes H-4 Hercules, the “Spruce Goose.” This would have been a hell of a plane had it been made available several years earlier, but by the time it flew it was not only no longer needed, it was obsolete. being made largely of wood, its durability out in the world would be questionable. During wartime this might have been a small issue; they probably couldn’t be expected to have a long lifespan. They’d get taken out by enemy action, by crashes and by wear and tear long before weather and aging would do them in. But in civilian service, the aircraft seems unlikely to have stood up well for long periods.
An all-metal version with turboprops? that might’ve been a hell of a sight to see all through the 1950’s.
Nov 062022
The model AGM-86 Air Launch Cruise Missile began life as a decoy missile, sort of an updated “Quail.” it was decided that the decoy could carry a nuclear warhead, and thus provide a lot more service; this began its development as a cruise missile. As originally envisaged, it had to fit in the some bays that could hold the AGM-69 SRAM missile; this made sense in a lot of ways but strictly limited its capabilities due to the short length. Efforts to increase the range of the missile included adding a droppable belly tank and stretching the fuselage for more internal fuel volume. The latter route was chose, along with making the nose much blunter and more voluminous.Both the external tank and the fuselage stretch meant that it could not long fit in internal SRAM bays, a tradeoff that was deemed worthwhile.
The illustration below dates from mid 1976 at the latest.
The full rez scan has been uploaded to the 2022-11 APR Extras folder on Dropbox for $4 and up APR Patrons/subscribers.
Nov 052022
An artists rendering of the Republic A-10 circa 1971. This is very nearly the final design, but it differs in details; the cockpit canopy is a little off, for instance.
Nov 032022
An Aerojet rendering, unfortunately not in color, of the Small ICBM (MGM-134 “Midgetman”) from the 80’s. This was a single-warhead missile meant specifically to be carried by and launched from an off-road truck/trailer capable of withstanding a reasonably nearby nuclear blast. The image hear focuses on the second stage; like all post-Minuteman US ICBM’s, the SICBM was solid fueled. The USSR gave up the ghost and as a consequence the SICBM program was cancelled in 1992.
Nov 012022
The October 2022 rewards are available for APR Patrons and Subscribers. This latest package includes:
Large format art: A Bell Aerospace painting of the D188A VTOL fighter/bomber
Document: “Standard Aircraft Characteristics – Convair Class VF Seaplane Night Fighter (SKATE)” diagrams and data for seaplane jet fighter
Document: “21St Century Aerospace – The 20th Century Challenge,” General Dynamics presentation, late 80’s about hypersonics/NASP. From photographs.
Document: “Prototype X-14 VTOL Aircraft,” Bell Aerospace presentation, 1971, on the “SeaKat” operational naval VTOL. From photos, but art and diagrams were also scanned for clarity.
CAD Diagram ($5 and up): XB-70 Valkyrie forward fuselage configuration
If you would like to help fund the acquisition and preservation of such things, along with getting high quality scans for yourself, please consider signing on either for the APR Patreon or the APR Monthly Historical Documents Program. Back issues are available for purchase by patrons and subscribers.
Oct 302022
The YouTube channel “Found and Explained” just released a video on the 4,000 ton Orion Battleship, with the model used based on my reconstruction from issue V2N2 of “Aerospace Projects Review.” The video was sponsored by a “Star Trek” video game, so there are a *lot* of Star Trek references in the video.
For more information on the project, including blueprints, be sure to check out issue v2N2.
Oct 292022
A Boeing concept from 1983 for an Orbital Transfer Vehicle. This vehicle would change the orbit of the payload not only propulsively, but by using aerodynamic drag to slow the vehicle at perigee. When returning a payload from geosynchronous orbit, it would dive into the upper atmosphere and use aerodynamic lift and drag to slow into a much lower orbit, with propulsive adjustments to put it into a circular orbit for rendezvous with a space Shuttle for recovery or servicing. This particular design was inflatable (creating a lifting body akin to a stretched-out “ASSET” shape) and used an extendable/stowable nozzle. Note that it is entering “upside down” so that the lift forces generated are trying to force it *closer* to Earth, rather than trying to bounce off the atmosphere.
Orbital velocities at geosynchronous are slower than in low Earth orbit… about half the speed. So a relatively small change in velocity at geosynchronous will turn the circular orbit into a sharply elliptical one, with a perigee close to Earth. But that velocity at perigee is much faster than circular orbit velocity, so shedding speed using “free” aerodynamic forces makes sense… if you can pull it off.
Oct 282022
Currently on ebay is an aluminum model of a lifting body. The rear of the vehicle is that of the M1 or M2, but the nose is distinctly conical. The lack of useful volume leads me to think that if this is a legit wind tunnel model (rather than something someone just knocked out at a machine shop for giggles), then it’s not a design for a manned vehicle, either test or operational space logistics. Rather it would be something like:
1) A basic subscale research vehicle like ASSET
2) A concept for a maneuverable entry vehicle for a military system. An ICBM warhead, perhaps designed to glide either for range extension, to avoid incoming ABMs, or to maneuver to avoid tracking systems and come in from unexpected directions.
3) Or it’s just a vague, generic “let’s look at everything” shape.
The nose of the model does not inspire a great deal of confidence… it looks a bit unfinished, with some sharp-ish corners that don’t seem like they should be there.
If anyone knows better, by all means speak up…
