Feeds

LOHAN: Reader vacuum pump plans really suck

Top quality amateur boffinry from El Reg spaceplane fans

The smart choice: opportunity from uncertainty

We at El Reg's Special Projects Bureau are, as ever, grateful to all those readers who offered suggestions for the low-cost, garden-shed vacuum pump rig we need for our Rocketry Experimental High Altitude Barosimulator (REHAB) experiment.

Click here for a bigger version of the LOHAN graphicOur bold plan is to stick the proposed power plant for our Low Orbit Helium Assisted Navigator (LOHAN) spaceplane – an AeroTech RC 32/60-100NS rocket motor – into a homemade hypobaric test chamber.

Below is the final concept graphic as to just how that will work, amended from previous versions to take into account your design concerns.

There's more on how the whole thing works here, but for those of you already up to speed on the plan, the only significant change is that the igniter and temperature sensor wires now pass through the top plate rubber seal. This means we don't need to bother with cable feedthroughs screwed into the wall of the inner tube.

Our revised REHAB hypobaric test rig

Note that as as we draw a vacuum, the top plate will be pulled firmly down onto the seal and the wires, and the whole lid should be airtight enough for the short duration of the test.

So, that's all under control, but how are we going to create a vacuum of 15mmHg?

Well, we threw that problem over to you lot, and you can see some of the splendid and ingenious ideas right here.

Your cunning plans ranged from using condensing steam to bloody enormous columns of water, via Magdeburg hemispheres and vehicle air con pumps.

There were plenty of votes for water-powered aspirator pumps, but a quick shufti online revealed that to get a decent vacuum we'd have to shell out a wad of cash – something we're trying to avoid here.

Which is why, of course, we don't buy buy a proper vacuum pump and be done with it.

This leads us to by far the most popular and cost-effective suggestion: the second-hand fridge compressor, which can be bodged to suck and, according to some of you, will deliver the required vacuum.

We shall see, because said compressor is going to be our first line of attack. Rather handily, my local fridge-fixing chaps have promised a couple of units for free, having immediately grasped just what the mad Englishman intended to do with them, and agreeing with Reg readers that the idea has legs.

So, it's a case of suck it and see. If it doesn't work, we'll have a rethink and come up with a fall-back solution, so some of your more esoteric concepts may yet see the light of day. ®

Bootnote

I'd like to offer a very big ta very much to those readers who offered kit they happened to have lying around in the shed for our REHAB experiment. The problem is, you're all in the UK and the US, and I'm in Spain, so it'd end up costing us more to get the stuff here than bodge something locally.

Nonetheless, it's much appreciated.

The Power of One Infographic

More from The Register

next story
World Solar Challenge contender claims new speed record
One charge sees Sunswift travel 500kms at over 100 km/h
SMELL YOU LATER, LOSERS – Dumbo tells rats, dogs... humans
Junk in the trunk? That's what people have
The Sun took a day off last week and made NO sunspots
Someone needs to get that lazy star cooking again before things get cold around here
Boffins discuss AI space program at hush-hush IARPA confab
IBM, MIT, plenty of others invited to fill Uncle Sam's spy toolchest, but where's Google?
Bad back? Show some spine and stop popping paracetamol
Study finds common pain-killer doesn't reduce pain or shorten recovery
Forty-five years ago: FOOTPRINTS FOUND ON MOON
NASA won't be back any time soon, sadly
Jurassic squawk: Dinos were Earth's early FEATHERED friends
Boffins research: Ancient dinos may all have had 'potential' fluff
prev story

Whitepapers

Top three mobile application threats
Prevent sensitive data leakage over insecure channels or stolen mobile devices.
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.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
Build a business case: developing custom apps
Learn how to maximize the value of custom applications by accelerating and simplifying their development.