Jan 232018

Currently winging their way from Ukraine to yours truly are two vintage brochures on the Antonov 225. These were picked up on ebay, purchases made possible by patrons of the APR Patreon. These brochures will in due course end up on the APR Patreon catalog, to be voted for as possible monthly rewards for the patrons.

If you’re interested in helping to preserve this sort of aerospace artifact, and also interested in getting high-rez scans of them, consider signing on to the APR Patreon.


 Posted by at 7:35 pm
Jan 172018

The Soviet Tsar Bomb, dropped in 1961 and with a yield of around 50 megatons (backed down from the design yield of 100 megatons) is acknowledged as the biggest bomb ever tested. But is it the most powerful bomb ever designed, or ever built? I’ve discovered some snippets of evidence that the US *may* have designed, and even built, an even bigger bomb.

Several frustratingly unenlightening reports give bits and pieces of information on a bomb code-named “Flashback.” This device was apparently air-dropped near Johnston Atoll. “Flashback” was designed by Sandia Labs and flown from Kirtland Air Force Base to Oahu, Hawaii and then to Johnston Atoll. There are some Terrible Quality Photos:

The Flashback bomb was so big that it could not quite fit within the confines of the B-52 bomb bay, and required the removal of the bomb bay doors.

Of course, this could have been purely an aerodynamic shape. Or perhaps it was a large conventional bomb, a giant “Daisy Cutter.” Or perhaps it wasn’t an actual bomb as such, but just some sort of science experiment to be dropped from an aircraft. Lots of possibilities. But those possibilities drop away with some of the hints that are provided, such as:


This came from an electromagnetic radiation effects report, describing – seemingly – the effect of radio emissions from the B-52 upon the electronics of the Flashback bomb. Since the bomb projected well below the belly, it was subject not only to very cold temperatures but also to intense radio transmissions from the antennae below the B-52 fuselage, so it makes sense they’d test for that. You don’t want the B-52’s communications to cause the bombs fuzing to go screwy. In this particular test, the parachute was not packed within the tail of the Flashback; instead test instruments were fitted there. More tellingly, “All HE (high explosive) and nuclear components were deleted.” Emphasis mine. Additionally, “A simulator was used to replace the warhead.”

You don’t have a warhead in a science package. You don’t have nuclear components in a conventional bomb. and if this was simply an aerodynamic and mass simulator of a proposed bomb… you wouldn’t remove the nuclear materials, because you wouldn’t have installed them in the first place. You don’t fill a mockup full of jet fuel, after all.

Such details as the weight of the unit and the yield of the device are seemingly not given. But they can be guessed at. A report on testing of the tailfin has this:

I’m not quite sure how that load of 36,000 pounds would relate to any actual forces applied to an actual bomb, but it *may* indicate the weight.

Other reports list the sizes and weights of items to be shipped to Oahu (and then to Johnston Atoll) for the test. Some of them are intriguing… what is “EMPTV?” TV certainly means “test vehicle.” But does “EMP” mean Electromagnetic Pulse? If so, does that mean another bomb-like unit, or just a science package, meant to be *hit* with an EMP to see how it reacts? Or is it a specific EMP generator, to be dropped out of an aircraft? Whatever it is, it weighed 14,500 pounds and was around 221 inches long and perhaps 59 or so inches in diameter, and was quite classified (SRD = Secret Restricted Data… “Data concerning the design, manufacture, or utilization of atomic weapons; production of special nuclear material; or use of special nuclear material in the production of energy“).

And there’s 38,000 pounds of “test equipment,” which could be anything:

There was also this:

Here, the “BTV” is the “Big Test Vehicle,” 25,000 pounds, 309 inches long by up to 76 inches in diameter, also classified SRD. Big as this is, though, it’s possibly not the device hanging below the B-52’s belly; the BTV is referenced several times in a way that seems to make it distinct from the Flashback Test Vehicle. But perhaps they are the same thing.

The Flashback Test Vehicle, fortunately, was shown in a fair diagram of a wind tunnel model. Full scale, it was 297 inches long (not counting parachute pack or what appear to be antennae) and was ~96 inches in diameter. This makes it bigger, and presumably heavier, than the BTV. So 36,000 pounds is not unreasonable.

Other ill-described tests show the Flashback as a much smaller unit than the bomb. This, *perhaps,* is merely the “physics package” of the device. This test, illustrated with one of histories worst-quality photos, was carried out in a very cold high altitude chamber, and shows two more mysteries: the “Companion Test Vehicles,” or CTVs, which are unexplained. Speculating wildly, they might have been designed to have the same ballistic properties as the Flashback, so if you drop them from the B-52 along with the Flashback, they’ll fall along with it, following the same trajectory and staying reasonably close. Perhaps thy had cameras. perhaps they had sensors. Perhaps they had transmitters. Who knows.

And there was also the “UTV.” No further data.

Perhaps the Flashback, BTV, EMPTV and UTV were all different sizes of new gigantic bombs…?

Code names generally have no relationship to the subject, but are chosen essentially at random. One would never know that “Copper Canyon” was a program to develop a scramjet SSTO. Similarly, “Operation Paddlewheel” tells nothing. But perhaps, just barely, “Flashback” might have some meaning. Comparing the Flashback to the Tsar Bomb, it it remarkable how similar they are in terms of both size and shape. One might be forgiven for wondering if Flashback was the end result of someone trying to design a Really Big Bomb based on nothing more than a verbal description of the Tsar Bomb, given, perhaps, by a spy or defector. So *perhaps* this project was a “flash back” to the earlier Soviet design. If so, what was the purpose? Was it to give the United States the same insanely pointless capability? Or was it just to find out what the capabilities and limitations the Soviets had gifted or saddled themselves with?

Using the wind tunnel model diagram, I’ve reconstructed the Flashback to scale with the Tsar Bomb:

As can be seen, the Flashback had much the same configuration, but was substantially “fatter.” Impossible to say if that was because the US designers needed the extra diameter to get the same yield (theoretically 100 megatons), or if Sandia Labs went head and designed themselves an even bigger bang. What use is a 200 megaton bomb? Not much. But then, neither is a 100 megaton bomb, especially one so big that the carrier aircraft essentially has to *lumber* to the target all the while carrying the worlds largest bullseye.

As always, if anyone has any further info, I’d love to see it.

PS: I’ve taken the Flashback model and have turned it into 2D CAD diagrams, including scale comparison with the Tsar and showing it stuffed into the B-52’s belly. This diagram will be one of this months rewards for Patrons of the APR Patreon. A simplified version will be included at the $5 level; the full diagram will be in the $8 level rewards package. So if you’d like access… sign up for the APR Patreon.


It’s good to get a fresh perspective. Sadly, the perspective emailed to me was that the Flashback sure looked like a missile nosecone. So I pulled up the Flashback diagram I made from the wind tunnel model diagrams and put the RV from the Titan II ICBM on top of it. It’s not an exact match, but it’s distressingly close. If it wasn’t for the noticeably larger radius of the Flashbacks nose, I’d say it was spot-on… the outer diameter and angle are incredibly close matches.

So…what would be the point of that? Some sort of science experiment, clearly, rather than a weapons test. But what point would there be in dropping a Titan RV from a B-52? Why dangle it from a chute? Why add the heavy tail & fin assembly?

If it turns out that this was an experiment with the Titan RV, that would be less interesting than the revelation that the US developed a 50 to 100 megaton nuke. But it’s still interesting. Just not *as* interesting.

 Posted by at 9:31 pm
Jan 142018

A 1966 Aerojet concept for a space probe with a nuclear reactor and ion engines. Note the largish thermal radiator “wings;” such things are usually left off spacecraft in science fiction, but they are a vital part of any nuclear spacecraft. Nukes, after all, are simply heat sources; in order to get useful electrical power out of them, the heat must be used to boil a working fluid which runs a turbogenerator; and the hot gas then needs to be condensed back to a liquid by radiating the heat way to space. And thermal radiation is a terribly slow and weak process, necessitating large radiators. Electricity can also be created with thermionic systems, which generate electricity across a thermal differential… hot on one side, cold on the other. But unless the cold side it attached to some radiators, the cold side will soon be just as hot as the hot side, and then… no thermal differential, no power generation.

Note also that even with a substantial powerplant and the sizable bank of ion engines, acceleration is going to be creakingly slow. Thus you can get away with spindly structures. The reactor itself is the tiny little tin can-looking thing, top and centerline; the U-shaped structure around it is a radiation shield protecting the electronics, structure and radiators from the radiation spat out by the reactor.

 Posted by at 2:38 am
Jan 092018

The Curtiss-Wright X-19 was a reasonably successful experimental tilt-prop VTOL aircraft from the first half of the 1960’s. Two aircraft were built; one crashed, one is at the USAF Museum in Dayton (I believe it’s in a restoration facility). The Defense Technical Information Center has two CW documents in PDF format that cover the technology of the X-19 in some detail:





One of the documents includes a fold-out three-view diagram of the X-19, scanned in glorious Extra No color two-bit black and white as two separate pages. I’ve stitched them back together and tried to make the diagram look reasonably good; I’ve uploaded the full-rez result of my effort to the 2018-0 APR Extras folder on Dropbox, available to all APR patrons at the $4 level and higher.

Support the APR Patreon to help bring more of this sort of thing to light!



 Posted by at 12:04 am
Jan 062018

The L-2000 was Lockheed’s entrance into the mid-1960’s FAA contest to design and develop an American supersonic transport. The FAA wanted the US to have an SST substantially better than the Anglo-French Concorde, with up to 250 passengers and a cruise speed of up to Mach 3 (as fast as an SR-71). Interestingly, the Concorde was not expected to be a long0lived design, but rather was simply going to be the *first* SST, a technology demonstrator, a diplomatic endeavor between historic enemies Britain and France, a flying sales brochure for Angle-French industry. And the Tupolev Tu 144 was an attempt to put something, *anything*, into the air first.

In the end, the FAA selected the Boeing 2707 design, ending the L-2000. And after great promise was shown, politics killed the Boeing 2707, ending substantial forward progress in civil aviation. Since then, air flight has gotten cheaper and more efficient, but it has not gotten any faster… and it certainly hasn’t become more comfortable.

This artwork depicts the final or near-final L-2000 concept, a double-delta configuration vaguely like a larger Concorde in shape. The Boeing design started off as a swing-wing configuration but became a fixed, tailed design prior to cancellation.


I’ve uploaded the full rez scans to the 2018-01 APR Extras Dropbox folder, available to all current APR Patrons at the $4 level and above. If you are interested in this and a great many other “extras” and monthly aerospace history rewards, please sign up for the APR Patreon. Chances are good that $4/month is far cheaper than your espresso/booze budget!


 Posted by at 8:09 pm
Jan 042018

A Rocketdyne concept for a space station from the late 1950’s. This was a sphere some 60 feet in diameter, with at least three counter-rotating internal centrifuges (think “2001’s” Discovery) to provide between 0.2 and 0.8 of an Earth-normal gravity. This station was to be parked in geosynchronous orbit, 22,400 miles up, and would weigh 250,000 pounds. The crew was to be a rather surprising 50 men. There are enough questions about the design that it can be safely assumed to either not be an entirely serious design, or to have been artistically greatly altered from the engineering concept. It *appears* to be equipped with:

  1. Possibly a small nuclear power source with attached rectangular radiators, held at some distance.
  2. Some sort of small rocket vehicle… possibly a proble launcher, or, since this was the 1950’s, possibly a nuclear weapon launcher
  3. A parabolic reflector, probably a solar mirror for concentrating sunlight and generating power
  4. An optical telescope
  5. A radar or communications dish that is pointed nowhere near towards Earth


 Posted by at 3:18 am
Jan 012018

This piece of art depicts the McDonnell-Douglas “Drawbridge” orbiter in orbit delivering a satellite. Note that the wing are deployed, even though they would be folded up during entry. The geometry of the craft was such that in order to get the cargo bay door open and payloads safely in and out, the wing needed to fold down out of the way.

This points out one of the reasons why you don’t often see a whole lot of “cool” stuff in aerospace… everything has tradeoffs. And needing the wings to constantly go up and down is a bit of a headache. When it comes to spacecraft, mass is a primary priority; the mechanisms needed to deploy the wings weight a lot… never mind the mechanisms needed to retract the wing again. As an example, the real space shuttle orbiter had no landing gear retraction system. And why should it? The landing gear is hardly something the Orbiter would ever need to retract. That could be done by the ground crew without adding weight and complexity to the craft itself.

Note that the Orbiter and the payload here seem to have not NASA markings, but Red Cross markings. I suspect that a number of variants of this piece of art would have been produced with several different markings (NASA and Pan Am being the obvious ones), but why exactly Red Cross? Dunno.

Also note that this might not be an actual “Drawbridge” design, as no extension mechanism for the wing s in evidence. This might be an oversight on the part of the artist; it might be that this was a fixed-wing design. Given the RCS thrusters on the wingtips, this is most likely *not* a Drawbridge.

I’ve uploaded the high-rez version of this artwork (11.2 megabyte 6271×4763 pixel JPG) to the APR Extras Dropbox folder for 2018-01, available to all APR Patrons at the $4 level and above. If you are interested in accessing this and other aerospace historical goodies, consider signing up for the APR Patreon.




 Posted by at 3:59 pm
Dec 302017

The rewards for APR Patrons have been issued. This month:

CAD Diagram: Marquardt hypersonic burning ramjet booster

Diagram: Convair Class VP Airplane High Performance Flying Boat

Document 1: Apollo Exploration Shelter System

Document 2: Chrysler Work Station Capsule (“work pod” for astronauts)

Document 3: Sikorsky S-97 “Raider” brochure


If you are interested in helping to preserve (and get copies of) this sort of thing, consider signing up for the APR Patreon.



 Posted by at 12:06 pm
Dec 252017

This piece of art depicts the McDonnell-Douglas “Drawbridge” orbiter staging off the manned flyback booster, showing the wings still folded against the sides of the fuselage. The wings served no purpose during ascent; they would only be used after-re-entry. Of course, in the event of a mission abort shortly after launch, the wings would need to deploy fairly quickly. There are no doubt numerous abort scenarios where the orbiter would be left intact after separation from a presumably stricken booster (or after a main engine failure on the orbiter stage), but would nevertheless still be doomed due to inability to get the wings deployed in time.

I’ve uploaded the high-rez version of this artwork (5 megabyte 3951×2121 pixel JPG) to the APR Extras Dropbox folder for 2017-12, available to all APR Patrons at the $4 level and above. If you are interested in accessing this and other aerospace historical goodies, consider signing up for the APR Patreon.



 Posted by at 4:18 pm
Dec 212017

The early development of the Space Shuttle was filled with bizarre designs, attempts to jam capabilities into existing technologies. One such unconventional concept came from McDonnell-Douglas: a low-cross-range orbiter atop a flyback booster. The orbiter, unlike the Shuttle Orbiter actually built, contained considerable internal propellant; the booster would get it up to high altitude and velocity, but the bulk of the actual delta V would come from the Orbiters own propulsion. The vehicle had small, straight wings that would fold up against the side of the fuselage for launch and for re-entry… but they would have to deploy on-orbit to allow the payload bay doors to open, and they’d deploy again once the craft had entered the atmosphere.

I’ve uploaded the high-rez version of this artwork (8 megabyte 5598×4529 pixel JPG) to the APR Extras Dropbox folder for 2017-12, available to all APR Patrons at the $4 level and above. If you are interested in accessing this and other aerospace historical goodies, consider signing up for the APR Patreon.







 Posted by at 9:23 pm