Test Tanks

Test Tanks

Postby Peter (Nebula) » Mon Sep 21, 2009 2:19 pm

I said I'd post a picture of the fuel and oxidiser tanks for the prototype engine test rig a while ago, so I've written a small article on the Nebula Aerospace site (http://www.nebula-aerospace.com).

Paul - if you'd like to use any of the pictures currently in the gallery (http://www.nebula-aerospace.com/multime ... allery.asp) to send to wired please feel free. Next up is a team photo just as soon as the boys' boiler suits arrive, followed by an article on the engine rig itself.

Best

Peter
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Re: Test Tanks

Postby pauldear » Wed Sep 23, 2009 6:14 pm

Hi Peter, many thanks for the offer of use of the photos.

Also, a question on the tanks: are they fully custom made, or cunning adaptations of something off-the-shelf?
Cheers,
Paul
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Re: Test Tanks

Postby Peter (Nebula) » Thu Sep 24, 2009 8:18 am

No probs.

In keeping with the spirit of the challenge, I'm trying to use reclaimed parts where possible and the cost savings are enormous.

Lets take the tanks as an example: To get a tank made up from scratch (two parts formed then welded together) would have first involved the making of a stamp tool at a cost of around £2.5K. Although I could then have had an unlimited number of tanks made, for small volumes (<1000) they would have worked out at around £70 each if the tool cost wasn't amortised in the price.

The alternative was to take a trip to Asda (other supermarkets are available!) and buy two 450psi 'Happy Time' helium cannisters complete with balloons. Helium is a scarce resource so we waited until a couple of birthday parties had passed before I could get to grips with them. The cost of the two tanks, helium and balloons was a grand total of £60 so as Richard would say - QED. Some drilling, welding, brazing, plumbing fixtures and painting later and I have my engine test tanks.

I'm adopting the same strategy with as much of the mechanics I can, and ScrewFix and eBay have become my new best friends. Even the combustion chambers of the engines themselves are made from ex CO2/Argon gas cannisters with some bespoke engineering for the throat and nozzles. The fuel filters are heating oil filters, the actuated valves are made from standard plumbing fitments coupled with high-torque radio control servos, the ignition coils are from 2 Ford Focuses etc. etc.

Of course its not always possible to use existing kit - the engine test stand is made from scratch, as is all of the electronics - but I've found you certainly don't need to keep on reinventing the wheel as kit with the specs needed is already there. This may seem obvious, but its come as a bit of a revalation to me.

Sorry, I appear to have gone on a bit. More photos soon.

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Peter
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Re: Test Tanks

Postby pauldear » Thu Sep 24, 2009 9:35 pm

Excellent! That is exactly what I hoped would happen here - creative reporpoising. I'm with you 100%; the components in modern consumer goods are so well-honed in terms of cost and design that it's hard to beat them. A Coke-can is probably better developed and refined, from an engineering perspective, than most of the things that got Mr. Armstrong to the moon. (Actually, the modern consumer may be better developed and refined than Mr. Armstrong, too, but that's a different matter.)
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Re: Test Tanks

Postby Iain » Sat Sep 26, 2009 10:47 pm

Looks good there Peter!
Looking foward to how your engine testing goes.

but I've found you certainly don't need to keep on reinventing the wheel as kit with the specs needed is already there. This may seem obvious, but its come as a bit of a revalation to me.



I found exactly the same thing! Came in to this with big ideas but soon found, why change something thats already been proven, stick with what works and go with it, and I must say if it wasn't for various people walking through the shed asking me what I'm doing (who don't know rockets so to speak) I might still be trying to reinvent the wheel, if they had not offered me an idea!


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