Original URL: http://www.theregister.co.uk/2013/09/27/lohan_doomsday_box/

LOHAN twangs BRASTRAP to unfetter mighty orbs

Our flight abort doomsday box will make fire in the sky

By Lester Haines

Posted in SPB, 27th September 2013 15:02 GMT

Pics+Vid Capping a hectic month for the Low Orbit Helium Assisted Navigator (LOHAN) team - in which we revealed the magnificent Vulture 2 spaceplane, rescued our heroic playmonaut from the side of a Spanish mountain and finally got a rocket motor igniter to go bang at 20,000m - we're delighted to report that the Big Red Abort Switch To Release Aerial Payload (BRASTRAP) doomsday box is up and running and ready to make fire in the sky.

To recap, the powers that be decided that anyone intending to mount a rocket-powered spaceplane under a fantastical flying truss, and suspend that from a mighty helium-filled orb, will require the services of an emergency cut-down lest the payload menace a centre of population.

Cue said box of doom, constructed by LOHAN team member Dave Akerman, and named by a popular vote which secured reader Steve Davis a Rock Seven RockBLOCK Iridium satellite comms unit. Here's the BRASTRAP, ready for use by anyone with a black leather swivel chair and a white Persian cat:

Dave Akerman's emergency cut-down box

The BRASTRAP contains a Raspberry Pi...

The interior of the BRASTRAP doomsday box

...programmed to send an abort text message via wireless net connection, the Rock Seven servers, Iridium ground station, Iridium satellite network and finally the airborne RockBLOCK...

Top and bottom views of the RockBLOCK

...which in turn commands an attached Arduino Mini Pro to fire a pyrotechnic cut-down using a MOSFET:

Top and bottom views of the RockBLOCK-Arduino sandwich

There's more on the RockBLOCK-Arduino sandwich, and just how the abort system works, right here, but what you really want to know is, does this impressive rig actually deliver?

The answer, dear readers, is an explosive yes, as ground-based tests last week showed. Here's a sequence of video stills showing what happens to a small cut-down attached to the Arduino, about 60 seconds after you hit the BRASTRAP big red button (click on snap for engorged imagery):

Montage of video stills of the cut-down firing

The cut-down - put together by LOHAN rocket wrangler Paul Shackleton - comprises a stainless steel tube with a hole through which the payload suspension cable passes. A steel bolt inside the tube, driven by explosive charge trigged by E-Match*, simply blasts its way across the cable aperture, severing the cable and cutting free the payload.

Of course, Paul felt obliged to knock up a bigger version of the above, should we find ourselves having to cut steel hawsers, carbon fibre nanontube woven cables or Kevlar-coated titanium rope, and here's the resulting "tube of death" doing the business:

Our large pyro cut-down before and during firing

The stills don't do the cut-downs justice, so try this quick video overview of BRASTRAP and the cut-down system, which features moving pictures of things going bang:

Watch Video

Good stuff. So, that's the emergency cut-down sorted, and we think it's fair to say that never has so much impressive technology been deployed for the simple proposition of cutting a string in the stratosphere. ®

Bootnote

*Both components were tested at altitude during last week's rocket motor igniter flight, so we don't anticipate any problems.


Further LOHAN resources:

LOHAN - A Special Projects Bureau production in association with...

  • 3T RPD logo
  • University of Southampton logo
  • Applied Vacuum Engineering logo
  • Escher Technologies
  • Flashpoint Fireworks logo
  • HAB Supplies logo
  • Rock 7 logo

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