Monday, October 10, 2016

Rocketober 10

All this month I'm posting photos on Twitter for #Rocketober. They'll appear here with slightly expanded text.


Still under the weather, I've only taken a few more steps on construction of Sky Wolf.

The rocket comes with two inch-long launch lugs for a 1/4 inch launch rail. Simply gluing on the lugs would be the simplest option, but I also consider using launch rail buttons.

Why? Well, a couple of reasons. The first is that a launch rail is a nice and sturdy launch platform. Last fall, I had some trouble with a few heavier rockets which was partly due to some wobbly launch rods. That probably wouldn't be an issue for this rocket, as those were clusters. But the rod-based launch pads my club uses can be a little tricky sometimes. The bases of them are metal fence posts hammered into the ground, and the heads are on a swivel. Sometimes I have trouble getting the launch rod to point where I want it to. Either I can't make it cooperate and angle it into or away from the wind direction as I'd like, or I try to get the rod perfectly vertical and I can't do that.

The NAR recently recommended angling all launch rods and rails away from spectators rather than launching vertically. However, this is a guideline, rather than a rule. Sometimes, depending on the direction of the wind or the proximity of the spectators, launching vertically may be preferable. You have to use good judgment for safety - as well as to minimize risk of losing the rocket (so long as you observe safety first). I have had a few rockets go nearly horizontal because they weren't launched vertically (mostly two-stagers) and leave the field. So I want the option.

Our rail pads are easier to control.

Most high power rockets use the 1010 rail button for a 1-inch wide launch rail. While people do put 1010 buttons on smaller-diameter rockets such as this one, they're a bit big for my liking on a rocket this size.


Another option is the "mini button" from rail-buttons.com. This is a launch button for the smaller metric rail, sometimes called a 2020 rail. Still very sturdy, but with a much smaller button. My Ventris uses these buttons.


On a rocket the size of Sky Wolf, the mini button is less obtrusive. It doesn't even stick out as far as the launch lugs supplied with the kit.


A third button option is the "micro button," also from rail-buttons.com. It's for use with a MakerBeam launch rail, and is really small.


Micro buttons do stick out further than they need to for the MakerBeam rail, but can be trimmed with a hobby knife.


Sky Wolf is pretty small, and not very heavy, so the micro button might work just fine. But if I fly the rocket with an H motor, I'm just not sure. So I decide this time to go with the mini button.

I drill two pilot holes into the airframe, directly into the forward and aft centering rings, offering more support for the rail button screw. A drop of thin CA - cyanoacrylate (superglue) - into the holes will stiffen the paper fibers.


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