Register here

Author Topic: Mario Zippermayr and his work during WWII  (Read 28528 times)

Offline Orionblamblam

  • Secret Projects Guru
  • Top Contributor
  • CLEARANCE: Top Secret
  • ***
  • Posts: 7043
    • Aerospace Projects Review
Re: Mario Zippermayr and his work during WWII
« Reply #45 on: October 10, 2012, 10:12:07 am »
And it is possible to make such an explosion. When there is enough oxygen around dust, it will ignite. It have happened in some mils in USA, but with flour instead of coal dust.

It's easy to make a coal or flour-dust fire. What's needed is to make a coal-dust *detonation.* Short physics lesson: if you throw a handfull of flamable powder into the air towards a lit flame, you will get a nice impressive fireball. This is - or at least was, before society turned completely cowardly - done in many a middle-school chemistry lab. While the fireball is impressive, and might set some stuff on fire, its usefulness as a weapon is *seriously* limited. It is not an "explosion" in any meaningful sense... the flamefront propagation rate is well below the speed of sound. There is no damaging shockwave. And while there's fire, most of the fire it "up there" away from the target, and the bulk of the heat would be transmitted to the target via radiation. In contrast, a napalm attack would spread the fire directly *on* the target, transmitting heat via conduction. This is *vastly* more effective. The same amount of thermal energy in a napalm attack that may convert a human target into a charcoal briquette might, in a coal-dust fire, simply burn off his eyebrows and set his shirt on fire.
 
Where grain silos become interesting is that they are enclosed volumes that can, however briefly, contain pressure. This means that when the fire starts, the increased air temperature causes the air pressure to increase, and with nowhere for the hot air to go, the air pressure spikes. And as air pressure goes up, the burning rate also goes up, which drives air pressure up... a nice circular death spiral of increasing pressure and burn rate, until the grain silo explodes. This is the same basic process that turns a non-explosive pile of burning black powder into a pipe bomb.
 
Now if you want to weaponize coal dust, you have to do more than release a cloud and set fire to it. You have to release a cloud and cause it to *detonate.* This can be done, but it takes effort. Basicaly, you need to set off not a match, but a series of initiating high explosives. A *true* high explosive (RDX, frex) will, deployed properly, set up a sharp shock wave that passes through the unburnt cloud of coal. At the shock wave boundary, air pressure can be incredibly high (thousands to millions of psi); this increased air pressure will, as in the case described above, cause the burn rate to be incredibly high. If the air pressure is high enough to drive the coal dust fire burn rate high enough to be supersonic, then the coal dust can be said to be truly detonating, and will add its own energy to the shock wave, and it becomes self-propagating.
 
To get *really* nasty, your weaponized coal dust bomb needs to set off not one high explosive initiator, but a series of them. Preferably a ring of small bombs around the cloud of dust. Done properly, they will cause the cloud to detonate from the outside inward; in the center where the shockwaves meet you can get some truly astonishing temperatures and pressures. The sort that cause lungs to be ripped out through the mouth and turned inside out and then set on fire.
 
Gettign the initiator right is, I think, the big challenge with fuel-air explosives.
 
This sort of weapon is great for "soft" targets - buildings, aircraft, people. Not really very effective against hardened targets like bunkers or tanks.
 
Aerospace Projects Review


And so the endless circle of life comes to an end, meaningless and grim. Why did they live, and why did they die? No reason. Two hundred million years of evolution snuffed out, for in the end Nature is horrific and teaches us nothing

Offline viro

  • CLEARANCE: Restricted
  • Posts: 3
  • I really should change my personal text
Re: Mario Zippermayr and his work during WWII
« Reply #46 on: October 10, 2012, 12:17:09 pm »
Thx for that!

But all I want is those pics and some extra info if you got some... But that description was awesome thx

Offline Hamzalippischh

  • CLEARANCE: Secret
  • **
  • Posts: 276
    • Shapeways shop
Re: Mario Zippermayr and his work during WWII
« Reply #47 on: December 18, 2012, 08:14:10 am »
Hi folks, here is my artwork about the Pfeil Flugzeug : http://www.secretprojects.co.uk/forum/index.php/topic,16995.0/all.html

hope you enjoy

Regards
"I do not think there is any thrill that can go through the human heart like that felt by the inventor as he sees some creation of the brain unfolding to success... such emotions make a man forget food, sleep, friends, love, everything."
Nikola Tesla

Offline bluedonkey99

  • CLEARANCE: Restricted
  • Posts: 5
Re: Zippermayr Pfeil (Arrow)
« Reply #48 on: April 06, 2018, 04:18:51 am »
OK, here's the scan from the Simon book, along with my own attempt at reconstruction. Feel free to point and laugh... there's every reason to see this attempt as crap, especially the top view. There may be some sweepback on the leading edge, but it's hard to be sure.

Obviously the tail is missing, because it's not shown in the available photo.

As much as I'm a sucker for secret German projects - Its not that convincing as a secret jet plane is it - when viewing the clearer image?

The truss work looks more akin to a WWI box frame fuselage (with wire diagonal bracing to be added?) than even a WWII era approach with diagonal truss bracing ?

The "jet pipe" looks more like a section of rounded/feared fuselage - there inst any obvious place for an engine (if the cockpit is to the right of the object)? - which *may* continue forward, but is obscured by the jig.



Offline riggerrob

  • CLEARANCE: Secret
  • **
  • Posts: 251
  • I really should change my personal text
Re: Mario Zippermayr and his work during WWII
« Reply #49 on: April 07, 2018, 06:19:25 pm »
Fig. 67 looks more like a ground mock-up. As for diagonal bracing ..... the skin carries those loads in a semi-monocoque structure.

That airframe might reach supersonic speeds ..... straight down.

OTOH I highly doubt that that ultra low aspect ratio wing could land at a high angle of attack. Many people have experimented with low aspect ratio wings, but few succeeded. The closest are sharply-swept delta wings on supersonic airplanes. (e.g. Concorde airliner). At high angles of attack, the entire leading edge acts like a huge wing tip generating massive, conical vortexes. Those votexes generate plenty of lift, but also massive amounts of drag. Concorde has to be flown at precise air speeds to avoid getting too deep into the “drag bucket.” .... because it could not power its way out of the drag bucket.
OTOH delta-winged fighters can use after-burners to power their way out of the drag bucket.

Pfeil’s ultra low aspect ratio wing would generate massive amounts of drag, but little lift at high angles of attack.

Offline Hamzalippischh

  • CLEARANCE: Secret
  • **
  • Posts: 276
    • Shapeways shop
Re: Mario Zippermayr and his work during WWII
« Reply #50 on: April 07, 2018, 06:37:05 pm »
Photos of a scale model of the original Pfeil according to Philip Zippermayr, who shared this with me some time ago.
"I do not think there is any thrill that can go through the human heart like that felt by the inventor as he sees some creation of the brain unfolding to success... such emotions make a man forget food, sleep, friends, love, everything."
Nikola Tesla

Offline moin1900

  • CLEARANCE: Secret
  • **
  • Posts: 462
Re: Mario Zippermayr and his work during WWII
« Reply #51 on: June 16, 2018, 07:03:50 am »
Seems that Zippermayr was not the only one who worked on coal dust / fuel-air / FAE bombs.
Patent Nr / Veröffentlichungsnummer: DE680483
Title: Fliegerbombe für Kohlenstaubexplosionen
Inventor: Kurt von Haken
Year: 06.04.1933
The patent shows a sketch of a coal dust parachute bomb.

https://depatisnet.dpma.de/DepatisNet/depatisnet?action=einsteiger

https://patents.google.com/patent/DE680483C
« Last Edit: June 29, 2018, 07:17:24 am by Jemiba »