Fly-away Rail Guides with Stand-off

[jqavins]

My Slova Ukraini rocket has an onion top nose cone, so it needs stand-offs for its launch guides. I built it with lugs on stand-offs, but it turns out it's too heavy for my club's rids. So I need rail buttons with stand-offs, right? But those are even uglier than lugs on stand-offs, and the rocket isn't built to take buttons anyway.

So the answer in my mind is fly-away rail guides (FARGs) made or modified to incorporate the needed stand-off distance. These could be 3D printed, but my design process for such things is slow, and my friend's printer is down, and getting to a maker space to do the printing is a PITA.

My first thought was Apogee's FARGs, since they are all plywood and would be easy enough to modify. Apogee doesn't seem to sell them in the size I need, which is 66 mm (BT-80).

Addative Aerospace sells FARGs for 66 mm tube, and they look like they'd be a lot easier to modify than Apogee's (because they have buttons attached to the 3D printed part with screws, so all one would need would be standard hardware). But those cost a whopping $65! Nope.

has anyone else got a good idea?

 

[frogglicker]

My Slova Ukraini rocket has an onion top nose cone, so it needs stand-offs for its launch guides. I built it with lugs on stand-offs, but it turns out it's too heavy for my club's rids. So I need rail buttons with stand-offs, right? But those are even uglier than lugs on stand-offs, and the rocket isn't built to take buttons anyway.

So the answer in my mind is fly-away rail guides (FARGs) made or modified to incorporate the needed stand-off distance. These could be 3D printed, but my design process for such things is slow, and my friend's printer is down, and getting to a maker space to do the printing is a PITA.

My first thought was Apogee's FARGs, since they are all plywood and would be easy enough to modify. Apogee doesn't seem to sell them in the size I need, which is 66 mm (BT-80).

Addative Aerospace sells FARGs for 66 mm tube, and they look like they'd be a lot easier to modify than Apogee's (because they have buttons attached to the 3D printed part with screws, so all one would need would be standard hardware). But those cost a whopping $65! Nope.

has anyone else got a good idea?

Good morning, Joe. I found this on Thingiverse: https://www.thingiverse.com/thing:3706482

I'm not sure if this is what you need or not, but I'm sure it is modifiable to meet your needs. The author can make changes or if they are straightforward, I or others here would be happy to assist. Hope this helps.

 

[jqavins]

What I'm looking for is something like that, but with the buttons on stand-offs. It may be I could assemble this from the printed parts by adding pieces of tube and using longer screws to attach the buttons.


I'm not sure, but I may be better off designing a stand-off variant of Apogee's style of FARG, which is all laser cut plywood, and much easier to assemble.

 

[frogglicker]

let me see if I can augment this design for you. I wanted to this morning but... well, work. I'll post up the design tonight if I can get it done.

Looks like you need a stand-off of about 25mm or so.

 

[frogglicker]

I was also thinking about a nylon spacer/standoff like this: https://www.digikey.com/en/products/detail/raf-electronic-hardware/1133-6-N/7680665.
That would allow you to use one that is already built, but give you the "Get my Rocket away from the rail" distance. I just don't know that much about rails or fly-away harnesses since I have less than 10 launches off the rail. The weight of the rocket/fly-away would need to be considered when bolting everything together.

 

[jqavins]

The standoffs I drew are NOT to scale. I'll elaborate in the morning.

 

[frogglicker]

I took from the files (see above) the 70mm A and B sections and scaled them down by 94.29% which "should" get it to 66mm. Mother untested. Kid unapproved. You should be able to add an appropriate length standoff with rail buttons. I think that there are several ways to get the standoffs but resizing it to BT80 (66mm) is the real task here. I'll print it sometime this week and verify that it will work for this.

Here, I am demonstrating a cylinder of 66mm inside the clamp. The fit is perfect.

Have a great evening.

 

[jqavins]

Thank you very much.

 

[mh9162013]

I think one would need to be careful when adding stand-offs to away rail guides (FARG) with heavy rockets due to the torque. While I'm sure the FARGs can be built strong enough, I imagine the added torque from longer stand offs would add a lot more friction between the buttons and rail negating much (or all?) of the performance benefits from using the FARGs.

 

[jqavins]

That would be no worse, I think, than it is with launch lugs on stand-offs, which is the alternative in my current situation.