Old rocket. Convert to rail buttons?

I’ve got several old mid powered rockets. Most are at least 15 yrs old and I used launch lugs on them when I built them. It seems to be more common to use launch rails now. I’ve had one RSO say I should probably put rail buttons on them.

Has anyone else done this conversion on a built rocket? Any pointers? Or is it just shave off the lug and screw in the rail button. I could probably get close to the top centering ring with some careful measuring...give me something to screw into...

Here’s the first patient. A BT80 scratch Interceptor showing some battle scars. It weighs in at 2 lb. 9 oz.

I have converted several old rockets to rail buttons. Screwing into a centering ring is the right idea. That said, I’d leave the Interceptor as is. Great looking rocket and not worth the hassle of buttons. If it was a typical 3FNC that got a lot of rod whip then I’d say it’s worth the trouble. If the Interceptor flies ok off rods then even more reason to leave it alone.


Tony

I agree with Tony on both counts.

If the lugs work, don't fix them.

Really nice bird!

If you’re set on having rail launch as an option a set of conformal rail guides could be a better choice - they’ll probably fit the “look” of an Estes Interceptor nicely and it’s fairly simple to epoxy them on. Just a thought...

Is there room for a rail between all the odd fin angles? I'd check that before chopping off lugs.

(Or use rail button standoffs, that works too)

I agree with Tony, I’d leave the Interceptor as is.

The advantages of rails over rods is that the rails can be very long and there is no rod whip on windy days. You always have the option not to fly it if the rods are bending. For a rocket that size, though, I'd have to agree with others that it probably doesn't make sense to risk that beautiful finish by stripping off lugs and screwing in buttons. Just don't fly it on windy days.

(My opinion, and not even worth two cents. )

I prefer the airfoil shaped rail buttons from Giant Leap. I think they are a little sturdier than plain round buttons. Conformals are fine, but I've learned it can be difficult to rack a heavier rocket if not perfectly straight.

1. That interceptor is beautiful. I agree with everyone else on leaving it alone.

2. For other rockets, your proposed procedure contains an unnecessary step. Forget shaving off the lugs and just add the buttons somewhere else. Then you've got options.

Ok...I’ll leave the Interceptor alone. With all the fins, about the only place to put rail buttons would be right where the lugs are.

The upscale Sprint should be an easy conversion. And the Bomarc could definitely benefit from the rail’s stability on launch.

For those you convert, consider looking for something like this:
https://www.rocketryforum.com/goto/post?id=1924174#post-1924174

There may be a third option.
https://rail-buttons.com/minimicro.html

Sells mini and micro rail buttons.

I am thinking of two dowels, each just big enough to fit inside the current lugs. Each longer than the lugs by about 5mm each end, maybe a tich more,

I think you could put a rail button on the forward end of each dowel.

Drill a cotter pin hole at the opposite end

Alternative is to just use cell tape to hold it in flight, maybe make the aft end a little longer to hold more tape, there should be no stress pulling the dowel FORWARD as long as you gently slide it onto the rail. All the flight forces should be pulling the dowel aft.

Drop the dowels in the lugs with the buttons FORWARD, use the cotter pin or tape to hold the rear end in place,

You can paint the dowel white if you want, although it is only necessary to keep it on during flight.

If the dowels aren’t big enough to support a mini rail button, you could take a small piece of say, basswood, drill a hole in the edge to fit the forward end of the dowel in place, and use that as an attachment point for your rail button. With a little finesse you could probably sand/shape the base so it conforms to the rocket, although I think the dowel buttons would probably work without it.

As a plus, since they are easily removable you could probably use them on your other rockets as well.

Good ideas! Here’s my prototype lug to rail adapter. I think It will look better when it’s painted. It slides on, the the rail button keeps it in place. What do you think?

The side dowels keep it from twisting...may not be necessary.

That is... kind of awesome. Do they feel really secure?

What is the button itself attached to? Is the whole thing removable?

They look great. Are these going to be permanent or removable? If removable, I was thinking have the button FORWARD of the lug makes more sense, both on the rail and during acceleration and during coast and under chute all forces will be pushing the button AFT into the lug.

If I'm looking at this right, the fore of the middle dowel has a ring all the way round, to which are glued the outriggers.

The aft of the middle dowel has a hole which receives the railbutton screw, but also prevents it from sliding forward.

dhbarr is correct. Here are a few more pics. It seems very secure to me.

Yeah, I was right, that *is* awesome.

Could probably use that as a basis for a 3D-printed solution that would be really slim.

I've never seen this exact technique -- can we name it after Turbo ? :-D

EDIT: On re-read I see BABAR's contribution, mea culpa.

EDIT2: If you 3d printed these, make the tines of the launchfork overlong, and print continuous pilot holes in the flatted center? So fit, mark, trim, screw, fly.

That IS an awesome idea!!!
I have my pre-built w/lugs Estes PS IIs...4 of em, and was wondering for a solution to add buttons...
Your idea is BRILLIANT!!!
Yes....I'm going to steal it! LOL

I think I'll make the forward "catch/anti-twist" section out of thick epoxy (thinking "Fixit" Clay)....
Again...Brilliant!!!
Kudos!!!

And that is a NICE looking rocket!!!!

Really slick!

The "Turbo Button"???

mbeels said:

Really slick!

The "Turbo Button"???

Click to expand...

lugbut [emoji23]

dhbarr said:

EDIT: On re-read I see BABAR's contribution, mea culpa.

Click to expand...

That's true, he seems to have originated the idea.

dhbarr said:

If I'm looking at this right, the fore of the middle dowel has a ring all the way round, to which are glued the outriggers.

The aft of the middle dowel has a hole which receives the railbutton screw, but also prevents it from sliding forward.

Click to expand...

dhbarr said:

I've never seen this exact technique -- can we name it after Turbo ? :-D

EDIT: On re-read I see BABAR's contribution, mea culpa.

EDIT2: If you 3d printed these, make the tines of the launchfork overlong, and print continuous pilot holes in the flatted center? So fit, mark, trim, screw, fly.

Click to expand...

I missed the forward ring! That and the outriggers make this secure fore and aft AND take out the wobble. Should be as strong as the original lug and relatively easily removable. About the only weak spot is that the screw hole may wear out with multiple insertions and removals.

I have no experience with3D printing, but seems like you could make something like this, maybe a few version, adapter specifically for 1/8 and 3/16 lugs and maybe customized to more popular body tube sizes. Could be made fairly aerodynamic

It was fun being part of this!

Hope you get straight trails!

Tom

@OKTurbo , this would make a nice post on the Techniques section of the forum, maybe also on the 3D printing section!

LOL! Lug-Butt...nice!

Necessity is the mother of invention. This was a group effort...I just made the first prototype.

I'll try to get a few more made to try this coming weekend at the Tulsa Rocketry launch and report back.

There are quite a few variables...lug diameter and length. Straight cut or tapered like on the Interceptor. And the rocket body tube diameter.

BABAR said:

About the only weak spot is that the screw hole may wear out with multiple insertions and removals.

Click to expand...

One could harden the screw hole with thin CA or some sort of penetrating epoxy. Insert and remove the screw once to establish threads than apply hardener.

Or use a threaded insert, such as an embedded nut, and use a machine screw. That would be easy on a 3D printed version.

Lugbut option 3.1

KISS principle

Single dowel length of lug plus 5 mm.
Screw hole forward end.
Insert dowel until hole just forward of lug.
Insert button so rear edge overlaps front of lug. Tighten so button rear edge pinches lug between button and dowel.

Option 3.2

Dowel exact length of dowel.
Insert dowel into lug.
Drill pilot hole at mid lug level through lug opposite body tube, through outer surface of lug into dowel.
Remove dowel.
Harden hole in dowel with CA
At forward end of dowel place small ink at the "top" where the hole is so you know where the hole is when you stick dowel in lug.
Re insert dowel.
Place button screw through hole in lug into hole in dowel for use.
Of course when you remove the button for display you have a tiny hole which detracts from cosmetic appearance. Can't have that

Have @neil_w design a decal to go AROUND the hole, something like
"LOX Access Hatch"

"AUX Plasma Vent"