Flyaway rail guide

DeltaVee wrote:

They look great! Have you tried them out yet? I've toyed with the idea of fly-away lugs/guides etc. but I worry about fin damage if the spring loading isn't high enough (with balsa fins of course).

Thanks...so the spring loading is rather clever here...it was one of my design parameters and I believe I have a good, albeit rather old fashioned solution. It is an adjustable loading to suit the flier's needs and can be set really high...this thing snaps open like a mouse trap, thus the need for a damper to prevent hinge failure.

I probably would not use a fly away with balsa fins, but I am toying with a design precisely for delicate fin situations and fin strikes.

I do note that the fly-away, pushes itself away from the airframe upon opening. It's part of the design. However, with high initial thrust motors, and big fins, strikes are going to happen, have to weigh the pros and cons of the fly away before use.

I concur! However, the screws holding the rods are not going to be used frequently, and indeed, I would probably lock-tight them for a first use. The screws on the rail buttons however will likely see more use, you may notice that I kept the nuts for the button screws. What happens is the spring tension tends to flat out the inner diameter of the two buttons, since they are opposing themselves while on the rail. I have also tentatively (untested) addressed this issue too by using rollers, instead of one piece buttons. That was also a design parameter, I hope it works...we'll see.

curtisheisey wrote:

Nice design. "sudden slam open distance".



How about the 4 inch version/1515 rail?

LOL, it was late, coffee was not an option, perhaps "extending over time the sudden change in angular momentum" would have been a better choice but I own sudden slam open distance now, and my well that's my story and I'm sticking to it!

So this one would easily scale up, but yeah, that is a plan...I am going to design a 3 rod, instead of a 5 rod version. I don't really see the benefit that 5 rods provide over 3. But for some reason, I had 5 in my head, and 6 rods from the old broken one. But I guess, with 3, I could have made two of them...lol...again, coffee

BDB wrote:

This looks great! I broke my fly-away guide launching on Lake Winnipesaukee in March. I assume the cold weather made the printed parts more brittle. I'd be interested in a smaller version for my 38 mm minimum diameter rocket.

Because Winnipesaukee looks to be the future (for the foreseeable future) of HP in New England I am also looking to test during cold weather and will be researching cold weather suitable plastics. I would imagine some sort of reinforced TPU would work in this instance. Also a CF reinforced PC. I can print all of those. TPU will take forever though. (It prints really slowly).

I wonder how some of the wood infused PLA would work too? Might be funky looking, and tempting to throw on the campfire, but I have some research. But PLA is a very bad choice for outside as it is hydroscopic.

For now, until I find something more suitable though, PETG is going to be my default. It is pretty strong, it's dimensionally far superior to any of the other filaments (on my printer within 0.05mm tolerance...which is great for parts that needs precision.), and is a good choice for outside all weather use.

Plus, I feel that the design has greatly reduced the issue with these snapping, but you are correct, the extreme cold adds a new dimension to consider.