Buttons or Conformal Rail Guides

[Okee]

I have a kit that came with conformal rail guides, but I have extra buttons as well. The Conformal look easier, but the buttons are really no problem either. Is there a reason to go one over the other?

 

[Speaknoevil]

If it is a minimum diameter design (and it is not high-performance enough to justify using my launch tower), then conformal rail guides are what I use, otherwise buttons.

 

[Okee]

Reading between the lines - buttons are slightly more aerodynamic?

This is not high performance and the rails seem easier/more forgiving so I'm leaning that way.

 

[cerving]

Conformal rail guides are not very forgiving of misalignment... if you use them, it helps to have a piece of rail handy to align them with.

 

[manixFan]

Conformal guides also have a tendency to pop off it you twist the rocket at all as you are loading it on the rail. I’ve used them and finally settled on JB Weld to keep them in place. Good surface prep is a must, on both the rocket and guides.


Tony

 

[Speaknoevil]

Reading between the lines - buttons are slightly more aerodynamic?

Not quite sure on that. I use a Dremel and cut a single rail guide into two pieces and angle the leading edges so mine are quite a bit smaller than stock.

 

[Okee]

I can get them aligned - but popping off is a whole other level of issue...lol I have extra buttons, so maybe I will standardize on that.

 

[TonyL]

I thought conformal rail guides looked cool [they still do], but after fighting them on almost every single time [even when aligned correctly, the first one on can be quite finicky] and breaking off a couple, I chose to replace them with regular rail buttons rather than put the things back on.

 

[dr wogz]

Buttons. Smaller contact area on the rail.. And, generally made from a more slippery material



and all the stuff the above posters said..

 

[Funkworks]

Depends on the kit and your plans with it.

 

[Okee]

Thanks for all the comments! I've decided that I will put buttons on everything where it is an option.

 

[rvanler65]

Yeah I have conformal lunch lugs on 1 rocket........not a fan!! Have gone back to rail buttons.

 

[Mugs914]

I like rail guides myself. I think they look more like an actual rocket part (I'm kinda weird that way ). I guess they can be a bit finicky to get started on the rail sometimes, but it has never been an issue worth mentioning for me.

I use the Acme aluminum guides and like Speaknoevil said, I cut them in half. I always use JB Weld to stick 'em on the tube. I dremel some fairly major cross-hatch on the back of the guide and strip the tube down to fuzz, or heavily scuff fiberglass. If it is a bigger, heavier or faster rocket I like to drill a couple of holes through the middle of the guide and into the tube so that the JB mashes down in there good and makes a little rivet, just for extra mechanical bond. Never have had one come off yet.

You can see the two little holes (sorta) in this pic.

 

[mbeels]

I've used both, I usually prefer buttons. There are also the rail guides from Wildman that "look" aerodynamic and have a screw hole.

CONFORMAL RAIL GUIDES-2PK

Wildman Rocketry is your best source for rocketry supplies, rocket motors, and rocket kits for Tripoli, NAR, Team America (TARC), IREC, and NASA SLI along with hobby flying.

wildmanrocketry.com

 

[Mugs914]

Haven't seen those before. Those are nice!

 

[wsume99]

I printed my own version of the conformal buttons. Here's a set on my G Force. I doubt they are more aerodynamic than the standard round rail buttons but for me they are definitely cheaper.

 

[AfterBurners]

Conformal rail guides are not very forgiving of misalignment... if you use them, it helps to have a piece of rail handy to align them with.

Draw the line and center them that way. That's how I usually do it

 

[AfterBurners]

I like rail guides myself. I think they look more like an actual rocket part (I'm kinda weird that way ). I guess they can be a bit finicky to get started on the rail sometimes, but it has never been an issue worth mentioning for me.

I use the Acme aluminum guides and like Speaknoevil said, I cut them in half. I always use JB Weld to stick 'em on the tube. I dremel some fairly major cross-hatch on the back of the guide and strip the tube down to fuzz, or heavily scuff fiberglass. If it is a bigger, heavier or faster rocket I like to drill a couple of holes through the middle of the guide and into the tube so that the JB mashes down in there good and makes a little rivet, just for extra mechanical bond. Never have had one come off yet.

You can see the two little holes (sorta) in this pic.
View attachment 418624

Those look similar to Aerotech guides

 

[JackC]

My experience has been to use the Acme conformal guides if your rocket is minimum diameter. If you draw your lines on your airframe to help you center the guides, you should be fine. I've used them on a 5.5 inch Nike Smoke which has worked for years but my new thinking would be to use rail buttons on non-minimum diameter rockets.

I agree to use the Dremel rough sanding wheel to cross-hatch both the rear surface of the rails and the corresponding area on the rocket to create a proper attachment surface. Then I use JB Weld applied to the surface of the rocket and the rear surface of the rails. Once I've done this, they never pop-off.

If you're using an Acme fin can or a Fisher Max-Q fin can, I recommend using the 2.26 extended Acme conformal guides to create enough clearance between the rocket and the fin can. Apply the lower rail slightly above the top of the fin can to assure clearance.

 

[DRAGON64]

Years ago there was a concern of the conformal rail guides, the aluminum one, were galling the 8020 rails over time. I generally try to stay with buttons of 3D printed conformal guides.

 

[grouch]

You can use a long straight edge placed between the "nubs' of the conformal guides to align them. Glue one on first and center the other one off that once cured.

 

[KenECoyote]

On one of my builds I used both...rail guide in the back and button up front. Seems the best of both worlds (not much fighting to put on the rail) and looked pretty cool imo. If aerodynamics is your thing, I'd think the front button smooths the air for the back rail guide.

 

[cwbullet]

I like rail guides. it has a large attachment point.

 

[David_Stack]

Tim from Apogee did an analysis and paper a few years ago looking at aerodynamic impact of launch lugs, buttons, rail guides, etc:

https://www.apogeerockets.com/downloads/PDFs/launch-lug-drag.pdf

Results somewhat surprising when comparing buttons and rail guides...

 

[JackC]

Tim from Apogee did an analysis and paper a few years ago looking at aerodynamic impact of launch lugs, buttons, rail guides, etc:

https://www.apogeerockets.com/downloads/PDFs/launch-lug-drag.pdf

Results somewhat surprising when comparing buttons and rail guides...

Yes! The Acme rail guides have less drag according to the report.

 

[hobie1dog]

Sounds like a 50-50 mix of Proponents for each design.

 

[hball55]

Reading between the lines - buttons are slightly more aerodynamic?

This is not high performance and the rails seem easier/more forgiving so I'm leaning that way.

Just based on Rocksim results, conformal rail guides outperform rail buttons, though the difference isn’t significant enough to really matter.

 

[Tractionengines]

Here is what I have been using lately. Direct from 80/20. (# 6797 for 1010 rail, and # 6897 for 1515 rail) Low cost raw part. Takes me 20 minutes with hacksaw, sander, and drill press to finish into 1 screw or 2 screw version. Made from UHMW-PE (plastic, very similar to Teflon). So VERY smooth sliding in the rail. (No chance of damage to rails, like Aluminum guides.)
Only issue is you can NOT bond to the UHMW-PE. (Glue or Epoxy) SO SCREWS ARE REQUIRED. I drill out the pilot hole and then countersink for 8-32 flat-head screw.

 

[cwbullet]

Just based on Rocksim results, conformal rail guides outperform rail buttons, though the difference isn’t significant enough to really matter.

I am not surprised. I prefer the long connection of the rail guide over the point connection of the rail button. Rail buttons can allow rotation after the top one leaves the rail.

 

[cls]

Never got a good bond on the rail guide (aluminum), they pop off eventually. Screws and delrin, done.