Feeds

LOHAN fizzles forlornly in REHAB

Rocket motors feel the lack of pressure

  • alert
  • submit to reddit

Next gen security for virtualised datacentres

It's been a lively couple of days down at the Special Projects Bureau, with the first of our Rocketry Experimental High Altitude Barosimulator (REHAB) experiments, designed to determine whether solid propellant rocket motors will fire under simulated high altitude conditions.

Click here for a bigger version of the LOHAN graphicAs we previously explained, we decided to do the low pressure test first without using the dry ice required to bring the motor temperature down to a chilly -60°C.

Our reasoning was pretty simple. If the motors wouldn't fire at low pressure in an out-of-the-box state, then we'd need to address that issue first.

We promised you an impressive location for the first foray into REHAB, and we think we delivered. Here's me and SPB volunteers Federico Buenadicha (our CAD man) and Rui Luz posing in the Plaza de Toros in Béjar - a town in the neighbouring province of Salamanca. Note the official SPB T-shirt and some retro Reg apparel:

The REHAB team: Lester Haines, Federico Buenadicha and Rui Luz

Béjar's bullring is reckoned to be the oldest in Spain, with some of the original stone structure dating back to 1711. We're obliged to the mayor of Béjar, Alejo Riñones Rico, for allowing us the use of this magnificent structure, and to Juan González Castellano – the mayor of the nearby village of La Garganta, in Extremadura – for acting as intermediary in the negotiations.

Here's another snap of Federico and Rui, as we prepared the REHAB rig for a first blast:

Federico Buenadicha and Rui Luz in the bullring in Bejar

So, our two test units were: an AeroTech RC 32/60-100NS – seen here (clockwise from left) with its G-class reload, motor case, sealing ring, end cap and nozzle...

The AeroTech rocket motor components

...and a Cesaroni P29-1G casing, with a 57F59-12A "White Thunder" reload:

The components of the Cesaroni P29-1G motor

First up to the plate was the AeroTech motor. The Copperhead ignitor is, as the rocketeers among you will know, a delicate flower which required careful handling by me and Rui:

Lester and Rui prepare to connect the motor ignitor

Once we'd got the igniter cable connected to the Copperhead with croc clips, we wrapped the whole thing in insulating tape, to prevent a short against the REHAB chamber's metal casing...

Connecting the AeroTech Copperhead ignitor

...and then I carefully lowered the motor into place...

Lester lowers the motor into the REHAB chamber

...and seated the perspex lid on the silcone seal:

The motor in the chamber and the perspex lid in place

The silver thing you can see passing under the blue and brown igniter cable cores is the thermocouple cable, coated in high-temperature-resistant silicone and metal foil, as protection against the rocket exhaust.

In this case, the thermocouple wasn't connected to the motor, since temperature wasn't a consideration. For the record, though, the interior of the chamber was at a balmy 18°C.

We then just had to rig the mirror and monitoring camera, and we were ready to rock'n'roll:

The chamber with the monitoring video camera mounted on its tripod

Here's a closer view of the whole REHAB rig. In the foreground is a vintage piece of SPB kit: the Kodak Zx1 video camera which recorded the famous flight of PARIS's Vulture 1 aircraft:

The complete REHAB rig, ready to roll

Having drawn the short straw, Rui positioned himself to shut off the vacuum gauge isolation valve, as soon as the rocket motor fired:

Rui prepares to shut off if the vacuum pump isolation valve

This precaution was to prevent damage to the gauge caused by a sudden rise in chamber internal pressure, although in the event, there was little risk of that.

With the vacuum pump up and running, and the system at 20mbar, a dramatic countdown culminating in a slightly nervous press of the ignition button resulted in... absolutely nothing.

Or rather, an electrical continuity test showed that the Copperhead igniter had fired, but had failed to set off the motor propellant.

This didn't concern us unduly, since Copperheads have a reputation for being temperamental. Unfortunately, though, the Cesaroni unit behaved in a similar fashion, with the igniter blown and no rocket burn.

Here's what should have happened, as seen in our first run of the AeroTech motor last year:

The question is, why did the igniters fire but the powder fail to burn?

Both motor reloads have their own oxidiser, so the lack of oxygen shouldn't be an issue. Nonetheless, AeroTech president Gary Rosenfield told us last year he wasn't sure "if the motor will ignite reliably at that altitude without a burst plug or other means to retain internal pressure".

This could be the explanation, or more specifically, oxygen might be required to facilitate initial motor ignition.

Suffice it to say, we're going to get straight down to another test, and our first idea to close the end of the motor with a sacrificial silicone seal, which should act as Gary's "burst plug".

As ever, we invite reader comments/suggestions, and let's see if between us we can't crack this hypobaric problem...®

Further LOHAN resources:

  • New to LOHAN? Try this mission summary for enlightenment.
  • You can find full LOHAN coverage right here.
  • Join the expert LOHAN debate down at Reg forums.
  • All the LOHAN and Paper Aircraft Released Into Space (PARIS) vids live on YouTube.
  • For our SPB photo archive, proceed directly to Flickr.
  • We sometimes indulge in light consensual tweeting, as you can see here.

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

  • 3T RPD logo
  • University of Southampton logo
  • Applied Vacuum Engineering logo

Secure remote control for conventional and virtual desktops

More from The Register

next story
Our LOHAN spaceplane ballocket Kickstarter climbs through £8000
Through 25 per cent but more is needed: Get your UNIQUE rewards!
LOHAN tunes into ultra long range radio
And verily, Vultures shall speak status unto distant receivers
NASA to reformat Opportunity rover's memory from 125 million miles away
Interplanetary admins will back up data and get to work
SpaceX prototype rocket EXPLODES over Texas. 'Tricky' biz, says Elon Musk
No injuries or near injuries. Flight stayed in designated area
EOS, Lockheed to track space junk from Oz
WA facility gets laser-eyes out of the fog
Volcanic eruption in Iceland triggers CODE RED aviation warning
Lava-spitting Bárðarbunga prompts action from Met Office
LOHAN Kickstarter push breaks TWELVE THOUSAND POUNDS
That's right, folks, you've stumped up OVER 9,000 beer tokens - and counting
prev story

Whitepapers

Endpoint data privacy in the cloud is easier than you think
Innovations in encryption and storage resolve issues of data privacy and key requirements for companies to look for in a solution.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Advanced data protection for your virtualized environments
Find a natural fit for optimizing protection for the often resource-constrained data protection process found in virtual environments.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Next gen security for virtualised datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.