rail button question

Hey guys had a question, this is my Horizon54 and if your not farmiliar with the kit it's from BSD 67" tall and a 4" BT. My question is this is my first time using rail buttons and was wondering if this placement looked ok? one is just above aft CR and the other is 16" up from the bottom, I debated three but alot of people said for this size rocket two was fine and three also increases rail binding problems so I wanted some opinions from my fellow rockeholics...thanks.

Drew

Looks ok to me from the picture.

You don't want to add three if you don't need to (real long
rocket might need three). They will bind if not all in-line.

William

Yup. Button placement looks good to me, too.

Originally posted by irishwebber01
Hey guys had a question, this is my Horizon54 and if your not farmiliar with the kit it's from BSD 67" tall and a 4" BT. My question is this is my first time using rail buttons and was wondering if this placement looked ok? one is just above aft CR and the other is 16" up from the bottom, I debated three but alot of people said for this size rocket two was fine and three also increases rail binding problems so I wanted some opinions from my fellow rockeholics...thanks.

Drew

Click to expand...

The bottom rail button should be into the aft centering ring and the top button should be one to two calipers below the center of gravity when it's loaded like it would be on the pad. If the rocket weighs more then a few pounds then the top rail button should really be into a centering ring as well or some other type of positive retention.

Three buttons are OK to use but they have to be aligned dead on straight or you may have problems.

Andrew

I usually put on at the CG and one in the bottom CR, usually screwed into a threaded insert. 2 is definitely enough for a rocket this size - I wouldn't use 3.

Three is the count, no more, no less....

Anchor them into CR's for good strength if you can.

Remember - guidance stops as soon as you have only one rail button engaged. If you only use two and the forward one is pretty far forward, you will have substantially less useful rail to work with.

Let's say you have a six foot rail and a rocket with two buttons three feet apart - you in effect only have 3 feet of rail.

I put one in the aft CR.
I put one in the CR that I always use at the top of my fins.
I put one further up the rocket, in a CR, where convienient.

With my average short-finned rocket, the aft two buttons are less than a foot apart - costing me less than 1 foot of rail guidance.

Yes, they all need to be aligned.
Yes, they all need to be aligned even if you only use two....otherwise you get the Gambler effect.

On the rare rocket where I can only use two, I still put them at into the CR's at the top and bottom of the fins. This places a lot of twisting torque on the buttons, but is a workable solution if you make their mounting strong!

I used 2 8" apart on my Nike Apache since it has a transistion and it actually id one of my straightest flying rockets!

Ben

Thanks for all the great hints, I drilled the holes ran epoxy down into the hole and on the surface then screwed them in, theres about 1/8" of screw through the other side so I hope between the screw and epoxy they should be ok, seem really sturdy. it's a 54mm MMT so they protrude into the mmt cavity, which has been foamed with pml foam as well but they are not in to the CR's.

Location looks fine.

Most important thing is anchoring them. As others have mentioned, CR's are a good anchor. Personally, I'm not precise enough to find them through the wall.

If you're like me, use a fender washer and hex-nut.

Don't rely on epoxy. One day, you'll be out at the pad and sliding the rocket down the rail and something will lever it away from the rail and POP! out come the rail buttons.

I've seen it 4 times with others and did once on a rocket that had a tailcone. The tailcone rested against the blastplate standoff and became a lever to rip the un-anchored-buttons right off...

This works for me I hate lining up to a CR. If you rip this out you have other problems LOL!

Those lok pretty cool !! Yah if you tear one of those out there are deffinitely issues with the rocket.