Inevitable, isn't it? We come up with fun project ideas, order a bunch of stuff, and spend the next week anxiously watching a collection of UPS tracking numbers, agonizing over whether or not we bought the right components. Here's what I've got coming my way (you'll be happy to know I figured out HaD's text editor, so the links are inline):
- Contra-rotating propeller assembly: I ordered this before changing the design around a bit, and it's still not here (since I accidentally ordered it from HK's "global warehouse"). Probably still useful, I'll definitely check the motor thrust and so forth.
- Electronic speed controllers for above: 25 amp rating means they may not be adequate for the final design, but they'll be handy for testing purposes. Also, cheap.
- CFRP Sample 1 and CFRP Sample 2: The local waterjet outfit I'll likely use wanted a few chunks to try. I also want to fiddle around with it a bit; might try to rig up some kind of a cheap bend test apparatus. Incidentally, last night I ran the numbers on the current GB design and it looks like this stock will likely be too thick to hit my weight requirements. Oh well, it will still be useful for SOMETHING.
- ARM Cortex M4 eval boards: I could have sworn I ordered these from DK late last month but now I can't find an email record. I'll give it a few days and get another one if necessary.
- Brushless motor for thruster: Based on extensive use of the FlyBrushless database, I've pieced together what I believe could be a good motor for the GB thruster assembly. The site does a fair amount of real-world testing using props and a DIY thrust gauge, and it looks like these units (combined with the props I ordered below) could get me the 1kg thrust each I'm looking for.
- Props for the above thruster: Again, based on FlyBrushless tests. Pitch is a bit greater than the FB tests (4.5 vs 4), but this will give us a decent baseline. Hopefully.
- ESCs: Yeah, I have 25 amp units on the way, but it's kinda tough to say when those will arrive. I bought a set of 30amp units to be on the safe side and to give me plenty of headroom with the motors.
- Aluminum tube stock: Picked up a 4' length of this (one of the smaller sizes) to build a cheap thrust gauge. Discount Steel is right down the street, so I can grab this locally once they have it cut.
So... more updates to come when goodies start to arrive. I'm midway through the v04 CAD model, which integrates actual dimensions of the above parts (along with some other changes) into the design. I did a few tests on the space glue that showed up earlier this week and it seems like good stuff; we'll see how well it bonds to roughed-up CFRP plate.
Random gripe: The RC world is a pain in the ass. Motor specs are ostensibly designed to make selection easier, but looking at posted real-world results of thrust measurement, current draw, and V/RPM it's clear that they are often driven by the marketing department. Also, all the suppliers and brand names are new to me; the flashy graphics and bright decals seem to get in the way of substance. I get the feeling that a lot of brands are just relabeled, and all of the stuff actually comes out of the same factory. We'll see how the first run of tests goes.
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