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This is crazy

28 Mar 2024

So I'm restarting my pulsejet development work.

In anticipation of this, I set about ordering some raw materials and components that will be used.

Now I expected that many of the electronic items would obviously be cheaper to source from China and indeed, that is exactly the situation -- although the price difference is not as great as I had anticipated.

In fact, I'm presently using the Raspberry Pi Pico dual-core STM-based microcontroller for the early prototyping because it's "cheap enough" and readily available with an abundance of support.

The big shock came when I got down to the more mundane parts I ordered this week.

Ideally, a working pulsejet should be made from a high-temperature nickel alloy such as Inconel but this stuff costs an arm and a leg so for most development work I choose to use stainless steel as a lower-cost alternative.

Unfortunately, even the cheapest stainless steel still has an 8 percent nickel content and with this metal in high demand, due to EV battery manufacturing as much as anything, even stainless is not cheap these days.

Obviously, things such as 2.4m x 1.2m sheets of 0.7mm stainless steel will have to be bought locally -- I'd hate to think of the freight costs associated with shipping just a few sheets of this to NZ from a distant shore!

However, other stainless components such as mandrel-drawn 90 and 180 degree tubing bends are practical to source from places like China, so I took a look on AliExpress to get a comparison with local pricing.

Well smack my gob!

Here in New Zealand, the price of a 90 degree long-elbow made from 70mm 304 stainless tubing is $96

The same fitting, ordered from AliExpress is exactly half the price at $43

Both prices are before freight but AliExpress will only charge me $1.79 for shipping whereas I don't think you can have *anything* shipped within NZ for less than about $8 or so.


How on earth can this be?

I can understand how small, lightweight, low-volume electronic components can be much cheaper when sourced from China -- but chunks of metal?

Okay, to be fair, I did a bit more searching and found some cheaper local sources for these fittings but none of them match the AliExpress price.

The biggest shock however, came when I started looking for some direct-injection fuel injectors, like the ones that are used in many modern ICE cars.

Browse this page from the Repco website and you'll get a feel for the kind of price you'd be paying locally for such components.

Now let's check out what a direct-injeciton fuel injector costs on AliExpress.

Holy crap, that's a *huge* difference.

Yes, the Sino product will almost certainly be inferior but I'm not looking to get 100,000 Km of trouble-free motoring here, I just want something that will work long enough and well enough to do some development work.

I've not finished finalising the total inventory of parts that will be needed over the next few months but suffice to say that by shopping-Sino I'm going to be reducing my capital outlay by a sizeable sum. Of course QC issues will be factored into the total cost because I know that some of what I'll be ordering from China will turn out to be garbage but I fully expect the wins to outweigh the losses.

Stay tuned... this is going to be interesting.

Carpe Diem folks!

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