PDF Review – Page 4 – Aerospace Projects Review Blog

PDF Review: A nuclear flying wing

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Apr 052015

More than sixty years ago, the US government and various aeronautical contractors began examining the application of atomic energy to powering aircraft. A mountain of documentation was produced, much of which has been lost, forgotten or is still locked behind classification. But some things come out from time to time that provide tantalizing hints as to what the designers of the time were thinking.

One such document is a short memo from June, 1948, describing a lecture given to unnamed staff by one William van Zelm of the Glenn L. Martin Corporation, describing aspects of aircraft design for atomic flight. Being simply a description of the lecture, the details are lean, but a sketch was included:

The design, crude and simply reproduced as it is, looks very reminiscent of a number of “stealth” aircraft that have been designed over the years including the A-12 Avenger II and the General Dynamics “Sneaky Pete” concept. This one, of course, was nuclear powered and apparently capable of supersonic speeds. It would be interesting to find more about this particular design.

The memo can be downloaded HERE.

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PDF Review: White Dwarf Dyson Spheres

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Mar 282015

OK, right up front: What Freeman Dyson meant when he first described the concept now called a “Dyson Sphere” was that a civilization sufficiently advanced would build so many space habitats and solar power satellites that the cloud of ’em would blot out the star they orbit. Since the artificial structures would re-radiate the sunlight they receive as lower-energy infra-red (basic physics: if you want to maintain a stable temperature, total energy coming into the system needs to precisely balance total energy leaving), from the outside the Dyson sphere would appear dark… but in infra-red it’d be a great big glowing thing.

The idea of the vast cloud was quickly interpreted as a giant solid “bubble” around the star. This vast construct would absorb all of the suns output, and would result in a monumentally vast place to live. If the star was much like the sun, the Dyson Sphere would need to be at least one AU in radius to keep the temperature roughly Earthlike. But there are of course problems: primary of which is that no material known to science, theorized by science or even guessed at could withstand the stresses involved. Additionally, there’s the problem of gravity. There would be none on the inside of the shell, except for that produced by the star; if you stood on the inside of the shell, you’d fall “up” into the sun. If you stood on the outside of the shell, you’d still have the suns gravity pullign you down… but at 1 AU from the star, that gravity would be miniscule. The gravity added by the sphere itself would be vastly more miniscule, given that its mass would be a tiny fraction of the mass of the star. So to live in or under a Dyson sphere with a Sol-type sun, you’d need artificial gravity habitats, either rotating structures or whatever magical “gravity generators” you can scrape up.

But a new type of Dyson sphere has just been described by two fellers from the Department of Physics of Bogazici University, Bebek, Istanbul, Turkey. Instead of building the shell around a Sun-like star… build it around a white dwarf. The resulting shell will be far smaller if it is to be at the “habitable zone,” since white dwarfs are far less luminous than main sequence stars. But a side benefit here is that the reduced Dyson sphere radius (depending on the white dwarf… from about 2,000,000 km to a bit over 4,000,000 k) results in surface gravities right near Earth normal. So humans would be able to comfortably live on the surface, using energy intercepted within the sphere to provide illumination.

The down side is that the problems of physical stresses within the Dyson sphere, already bad with the 1-AU-type sphere, become much worse at the smaller radius and higher gravity loading. But presumably by the time humans are ready to tear planets apart to build shells around distant stars, we’ll have made important advances in the field of materials science.

Download the PDF file of the paper here:

Dyson Spheres around White Dwarfs

PDF Review: Recent Results in Rocket Flight Technique

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Mar 212015

Eugen Sanger was an Austrian engineer from the early/mid 20th century. While largely forgotten by the vast majority of everybody today, he is remembered, at least in aerospace circles, as the originator of the Silbervogel (“Silverbird”) rocket-powered suborbital bomber. This work was performed during WWII for the German government, and included some substantial rocket testing; the odd thing – though wholly in character for the Nazi regime – was that this work was entirely separate from the development work on the V-2 rocket. Had the efforts been brought together, chances are that German rocketry would have been further advanced by the end of the war.

In 1934, Sanger published a paper on advancement in liquid propellant rocketry, work that would later feed into his Silverbird effort. “Recent Results in Rocket Flight Technique” not only reported upon work done in developing a gas-oil and liquid oxygen burning rocket engine, but also proposals for manned rocket powered aircraft. The paper was originally written in German and granted the catchy title “Neuer Ergebnisse der Raketenflugtechnik,” but it was translated into English by the National Advisory Committee for Aeronautics in April of 1942. Why was it was translated just then? Depending on the speed of the translators, the work may have begun just after the American entry into WWII, which might indicate a bit more interest in German rocketry in certain portions of the US Government than has generally been understood.

The abstract & such for the report can be seen on the NASA Technical Report Server HERE. Or it can be directly downloaded as a 33 meg PDF HERE.

Note: my original plan for this writeup was to include verbiage along the lines of “Sorry that the two-bit black-and-white scan quality is so poor, but whatcha gonna do.” But in looking it up, I found that the original bleah-quality scan has been replaced with a higher quality full-color scan. This is a good thing!

Much more aerospace stuff is available via the APR Patreon.

PDF Review: Air Force Slang

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Mar 142015

This one is admittedly a bit different, but might be of some interest and/or use.

AIR FORCE MANUAL OU – 812

4 March 2015

Communications and Information

AIR FORCE SLANG

No, it’s not actually an official USAF manual. But its author(s) seems to know his subject.

PDF Review: Space Settlements, A Design Study

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Mar 022015

NASA SP-413, “Space Settlements, A Design Study,” was published in 1977 and brought together the results of a 1975 NASA-Ames Research Center effort to do a preliminary study of a giant torus space station for several thousand permanent inhabitants. It is a basic text on the subject of space colonies, but obtaining a copy of the printed book of course requires money (but not much… a quick check at abebooks.com shows them going for about $8) and online versions have typically been either black-and-white scan PDFs of indifferent quality, or versions rendered into painful HTML format. Fortunately, someone (it’s unclear to me who, though it seems a professional job) has scanned in the book and all the illustrations and reformatted the text into an all-new, clean PDF version.

The PDF can be downloaded HERE.

Much more aerospace stuff is available via the APR Patreon.

PDF Review: 1973 Senate testimony on Agile

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Feb 262015

A PDF pieced together from scans found on the Secret Projects forum of Senate testimony on the AIM-95 Agile air-to-air missile. Agile was, as the name might suggest, a close-in “dogfighting” missile, an attempt to incorporate the hard lessons learned by the USAF and USN getting their tails kicked in the skies over Viet Nam by scrappy Russian dogfighters pilots by scrappy Vietnamese pilots. The main advantage that the Agile provided over the Sidewinder was that the infra-red seeker was capable of looking further off boresight… in other words, you didn’t need to point the plane at the enemy before the missile could get a lock-on. While the AIM-95 Agile apparently worked just fine, it was simply cheaper to upgrade the Sidewinder.

The AIM-95 would be steered via vectoring the nozzle rather than aerodynamic control fins. Initial targeting was planned to be done by having a sight integrated into the pilots helmet.. where he looked, the missile looked. The AIM-95 was intended for use by the F-14 and then the F-15 as well, but it never entered service.

The PDF file is HERE.

Much more aerospace stuff is available via the APR Patreon.

PDF Review: Unconventional Submarine Propulsion Systems

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Feb 212015

Modern submarines (like the Seawolf and Virgina classes) are often propelled not by propellers, but by pumpjets. These are shrouded turbines with a number of blades, looking much like the inlets and compressors of modern high bypass turbofans. They provide propulsive improvement, but apparently more importantly they are quieter than exposed propellers. However, the details of their designs are often obscure, for the obvious fact that they make submarines stealthier vehicles.

One of the few pumpjets I’ve seen shown in any detail comes from a 1963 General Dynamics report covering unusual propulsion system options for submarines. At this early date it’s safe to assume that the resemblance to a modern pumpjet is probably fairly minimal beyond the overall concept and configuration, but it’s still an interesting look at a rarely seen technology Additionally, the pumpjet is about the *least* unconventional of the concepts shown in detail, which include props that are fitted to a ring at the maximum diameter of the hull and separate, podded propulsion systems (a common enough design feature on many surface vessels today) and cycloidal propulsion systems. All of the systems are compared by assuming they are applied to SSB(N)-616 USS Lafayette, a ballistic missile sub.

DESIGN STUDY REPORT: A SURVEY OF CONVENTIONAL AND UNCONVENTIONAL SUBMARINE PROPULSION SYSTEMS

This report can be downloaded from the Defense Technical Information Center website.

The link to the abstract is here.

The direct link to the PDF file is here.

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PDF Review: “Ignition!”

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Dec 272014

“Ignition! An informal history of liquid rocket propellants” was written by John D. Clark and published by Rutgers University in 1972. It is a classic text on the subject… a text which has not been reprinted since except by some print-on-demand types. If you find a copy of this book for less than several hundred dollars, you’ve lucked out. It’s a good read, both informative and entertaining.

Fortunately, someone went to the bother of scanning the whole thing and posting it as a PDF. I’m honestly unclear about the copyright implications, if any… but the scan has been openly and freely available for some years, so…

http://library.sciencemadness.org/library/books/ignition.pdf

Hmmm. It seems that I’ve completely flaked out on the PDF reviews for quite a while. And nobody said anything. Makes me wonder if maybe there’s just no interest in these? Shrug, oh well, moving on…

As always: check out the APR Patreon for info on how to help, and how to get rewards.

PDF Review: A Method of Reaching Extreme Altitudes

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Oct 312014

This is the fourth of four “PDF Reviews” I plan to have in October, to make up for the lack of any in September. The idea is to present interesting online resources for those interested in the sort of aerospace oddities that you can find in the pages of Aerospace Projects Review. This little project is supported through my Patreon campaign; at current levels, I’ll post two such reviews per month. If you’d like to see more, or just want to contribute to help me along, please consider becoming a patron.

A work of no small importance in the history of spaceflight is “A Method of Reaching Extreme Altitudes” by Robert Goddard. Published in 1919 while his early rocketry work was being funded by the Smithsonian, “Method” is one of the major works of rocket engineering of the 20th century. At this time of writing, Goddard had experimented only with solid rockets; liquid rockets still being in the future. But in “Method” Goddard began to show what rockets could be capable of. In his last section he discussed what would be needed to launch a rocket not just to high altitude, but to escape velocity and beyond, with some discussion of how much flash powder would be needed to be detected impacting (and flashing) on the darkened surface of the moon.

It was that last bit that caused all the trouble.

Goddard was not by nature a publicity hound. And the press of the time, once they got hold of the report, savaged him for what they – incorrectly – saw as a sensational proposal to actually build a moon rocket, coupled with a flawed understanding of physics on the part of some reporters and editorial writers. The resulting firestorm in the press served to popularize Goddards work and inspire rocketeers around the world… but it also inspired Goddard to be even more of a recluse. Had this not been published, or had it escaped the notice of the press, it’s interesting to speculate how history might have been different. Many German rocket scientists might not have been as inspired, while Goddard might have been less reclusive and thus more open to accepting assistance. The result *might* have been that WWII would have ended not with German rocketeers being sought all over the world, but American rockeeters in the same position… but victorious. The result of *that* would have been to potentially move the march to space forward by five to ten years, while denying to the Soviets much of the expertise of the Germans.

The Internet Archive has a scan of a Smithsonian copy of the report. Their copy has a number of hand-written corrections and notations, and appears to be a proof copy rather than one of the final published versions.

Link to the abstract page:

https://archive.org/details/methodreachinge00Godd

And directly to the PDF:

https://archive.org/download/methodreachinge00Godd/methodreachinge00Godd.pdf

PDF Bonus: Docking an XF-85 Goblin

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Oct 232014

This is the third of four “PDF Reviews” I plan to have in October, to make up for the lack of any in September. The idea is to present interesting online resources for those interested in the sort of aerospace oddities that you can find in the pages of Aerospace Projects Review. This little project is supported through my Patreon campaign; at current levels, I’ll post two such reviews per month. If you’d like to see more, or just want to contribute to help me along, please consider becoming a patron.

One of the odder American aircraft in the immediate post-war period was the McDonnell XP-85 “Goblin.” This was essentially the smallest jet fighter possible to build with the technology of the time… small so that it could be carried within the bomb bay of the Convair B-36. The B-36 could reach far, far beyond the range of any conceivable escort fighter, leaving it at the mercy of defending Soviet fighters; if it could carry a fighter jet with it, it might stand a chance. of course the idea was fairly ridiculous; the Goblin was the biggest plane that could be carried internally, yet would almost certainly stand little chance against a conventional fighter.

Dropping the fighter from the bomb bay would be fairly easy and straightforward. But getting it back was understood to be a challenge. The Goblin would rendezvous with a “trapeze” projected well below the bomb bay, outside of the turbulent airflow around the bombers fuselage. Once docked to the trapeze, it would be mechanically stabilized, the wings would fold up and the trapeze would retract, safely drawing the fighter into the bomb bay. That, at least, was the plan; actual testing with a B-29 showed that the docking rendezvous was far more difficult than envisioned.

This difficulty was not wholly unforeseen. In 1947, the Langley Aeronautical Lab ran a series of wind tunnel tests of a 1/10 scale model of the Goblin and the forward fuselage of a B-36. Tests were conducted with both “power off” and “power on” models; the power off models were well behaved when docked to the trapeze, but the power on models quickly underwent violent flailing. The tests were filmed, with small still images included in the test report; the power-on model response is dramatic, to say the least.

Stability and Control Characteristics of a 1/10-Scale Model of the McDonnell XP-85 Airplane While Attached to the Trapeze

Here’s the link to the NASA-NTRS abstract of the report.

And here’s the DIRECT LINK TO THE PDF.