From my perspective the cheapest way to approach Hybrids is to DIY, especially given exchange rates and shipping costs.

Thanks Drew,

Unfortunately, you need access to some sound machine shop and turning skills beyond what I possess. Some of WA's past members, such as Steven Forth, were active in this field some years ago. They even produced a low-powered assembly based on a disposable N02 canister. This looked identical to the now more common Co2 rechargers and was single-use.

Yes, I know the cylinders above are Co2 and NOT No2, but they look identical. 

I could not find No2 Recharge Cylinders on Amazon today, so I am unsure if they are still made. They were once about $10 for a box of 10, but that made them only about $1 each. While you will never certify on one compared to buying a pack of E motors, you could have a lot of low-powered fun with them.

I also have just looked on Ali-Express, and I can only find Co2 canisters there. (Perhaps they are no longer made.)

The design that Steve had was based on what was called Aerocon's S'Creamer Micro Hybrid. I understand this was a Rene Calsera design, which is ~22mm in diameter. I fly mine in 24mm mounts with a spacer made from a section of 24mm tubing that I cut lengthwise. I'd bet this one is also made from the same .875 standard aluminium tube, but I can't guarantee that. But then, if it were custom, I suspect it would be made to fit standard 24mm mounts perfectly.

BTW, you can always email Bob at Aerocon.

That was back in about 2005, but gee—I am dating myself now. (Little grey cells—don't abandon me now.) I recall it being about the equivalent of a large E motor.

I recall purchasing a Hybrid design manual from https://aeroconsystems.com/ sometime back. However, I can no longer access this or a great selection of publications that once existed on their website. Apart from the following technical manual, which can be downloaded below:

"Introduction to Hybrid Design"

If anyone is interested, I will see if I can dig out my copy.

I do have a copy of the original Rene Caldera micro hybrid designs, but a lathe with the ability to turn aluminium, brass and graphite is needed.

Otherwise, I believe Lee Dexter is still making them to order through www.micronitrorocketry.com. I have two of the micro hybrids that use the 8 gram nitrous oxide canisters (8.5 and 9 gram also fit) but 16 gram canisters are impossible to get as far as I know.

These are by far the absolute cheapest cost per flight though. The 8 and 9 gram canisters are around $1-1.20 each and fuel grains can be made for literally cents. I 3D print my own reloads too, so it’s under $1.50 per flight for me.

the downside is that they are not TRA certified motors and most nitrous canisters are steel, so you’re pretty much limited to private flights only - but given that you’re going to be in the D to E impulse range, there are plenty of suitable locations to fly privately anyway.

Aluminium canisters do exist, but again, hard to find in Australia. I had read somewhere that TRA was considering changing their stance on the steel canister but no idea if that’s still being considered or not.