Micro Buttons (RailButtons.com) Beta Test

Introduction

For the last few years, I have toyed with the idea of rail for rockets. The big limiting factor was finding rail that was small enough with the requisite stiffness. I wanted something small enough for LPR but to accommodate some, or perhaps even most, of the MPR range. I spent quite a bit of time searching for something that fit the requirements, but nothing ever seemed to fit the bill.

Enter OpenBeam

When Randy of RailButtons.com broached the idea of smaller rail buttons, I was certainly interested. However, it wasn’t until David Stribling mentioned OpenBeam (link https://www.rocketryforum.com/showthread.php?63585-Interest-in-mini-railbuttons&p=680255#post680255) that I thought the dream could become a reality. After securing some rail from David and micro buttons from Randy, I had the beginnings of a good test in the future.


More to come ...

Greg

The Button Sled

One thing I wanted to do is create a way to test multiple rockets. I didn’t want to permanently mount the buttons, since I didn’t know what the outcome of the test would be. I had the idea that one of the easiest way to do this is to have a removable platform to do this. To make the sled, I took a strip of 1/8” plywood that I purchased from Hobby Lobby, and used my power saw to cut a section to mount the buttons on. The raw button base came in at 2.38 grams (0.084 oz).



I attached one button at the head, which I call the “pilot button”, and the two standard buttons at the tail. I drilled three holes using a #50 drill bit to accommodate the button screws, which is a 2-56 size screw. I then used a 2-56 tap into the hole to assure that the screws had the proper thread pattern. Because the plywood was 1/8” thick, there would be 7 threads holding it inside the wood. The screws extended beyond the plywood, so I used a Dremel grinding shape to grind away the unneeded excess. Because the screws are plastic (not sure what kind) that only took a minute or so. I also shaped the fore and aft portion of the button base to make it a bit more aerodynamic. But micro button sled came in at 2.44 grams (0.086 oz).



More to come ...

Greg

op:

Rocket, Meet Button Sled

I had a scratchbuilt rocket that I thought would be a good candidate for the test. I used a strip of Mylar packing tape to attach it to the rocket, in keeping with the requirement to be used for testing on multiple rockets. The outside diameter of the rocket used was 1.33” and the bottom of the sled was attached near the base of the rocket.



More to come ...

Greg

Test Rocket 1, OpenBeam Pad Seup

Launch day, Saturday, April 12, 2014, Hearne, TX.

The first thing noticeable on this day were the winds. For most of the day, winds were at the limits of what you could fly. They winds were so much that we took down our canopy right after putting it up. There was more than one canopy that had to be actively held by folks when severe.

So I had good reason to go with the 2-meter length of OpenBeam launch rail. The longer length would assure a flight that would not weather-cock as much.

After loading it with an Estes B6-4, the weight on the pad would be 98 grams (3.457 oz).

After bringing the OpenBeam pad pieces to the LPR pad, two of my children helped me setup the pad and rack the rocket. After placing the rocket on the pad, I noticed that there were gaps with the button sled and wished I had used more tape. As I walked away, I took a few pics.










Greg

Test Rocket 1, First Flight

My biggest concern was the join area between the two rails. I relied on the younger eyes of my children rather than my own for this and trusted their judgment. If it past that juncture, I thought we would be home free. If it stalled at mid-rail, it just wasn’t going to be pretty. Regardless, the rocket on the rail rode freely by hand, and while not frictionless, was most likely a lot less friction than the typical lug.

After getting my iPhone in ready for video, it was time for the countdown. While not nervous, I was more concerned about what failure could occur and it probably showed on my face. I braced myself for some disappointment, because after all it’s the first time for a new system. I hate failure.

Finally the count reached zero, the button was pushed, and it was on its way.





Video Link:

https://www.flickr.com/photos/9960539@N07/13812291483/

More to come ...

Greg

GregGleason said:

Test Rocket 1, First Flight

My biggest concern was the join area between the two rails. I relied on the younger eyes of my children rather than my own for this and trusted their judgment. If it past that juncture, I thought we would be home free. If it stalled at mid-rail, it just wasn’t going to be pretty. Regardless, the rocket on the rail rode freely by hand, and while not frictionless, was most likely a lot less friction than the typical lug.

After getting my iPhone in ready for video, it was time for the countdown. While not nervous, I was more concerned about what failure could occur and it probably showed on my face. I braced myself for some disappointment, because after all it’s the first time for a new system. I hate failure.

Finally the count reached zero, the button was pushed, and it was on its way.

View attachment 169025



Video Link:

https://www.flickr.com/photos/9960539@N07/13812291483/

More to come ...

Greg

Click to expand...

Greg: I'm still wondering why you think you need to join two rails? talk about excessive!

Results of Test Rocket 1

The results were nominal. In spite of the wind (which you can see affecting the clothes and the hat of the club president) the flight went off the rod straight with no dramatic changes in direction of the flight. Looking at the video, there is a small wiggle beyond the rail, but the flight is essentially straight up. I’d call it a success.

But this was supposed to be the first test in a string. So the next step: MPR.

Greg

Test Rocket 2

The next test was on a mid-power rocket. The OD of the rocket is 2.60”, so it is a larger model rocket. Not only was it much longer (just the nose cone is about as long as the rocket used in test 1), it’s launch mass was 4.5 times greater at 477 grams (16.826 oz or a little over a pound). It’s motor was also an AP motor, a 24/40 RMS case with an E18-4W.

I transferred the button sled from the first rocket to the next one, and taped it using the same clear tape as I had on the first test. However, after racking the rocket the tape began to pull away from the airframe. Well that was frustrating. It was taken off the rack and the faulty tape was removed and secured it with masking tape. It wasn’t going to win any beauty contests, but it was functional and felt secure.



So back to the pad, and test rocket 2 was racked for a second time. The winds continued to be a problem. One thing I had not anticipated is the drag the rail had on a stiff wind. Even though the width is only 15mm (0.59”), when it’s length is 2 meters it will create enough force to knock it over. The good thing is that the join area was with a section of PVC with a chord area cut away. So when it fell the force “broke” at the PVC and didn’t cause any bending loads to go to the rail. I wish I could say it happened exactly the way I planned but I’m not that prescient. So whenever it happened we would stand it back up for launch and then remove the upper rail between launches.

When it was time to launch, I got my phone ready for the event. The button was pushed and the second rocket was away, but my videography of this launch was deplorable.



Video Link:

https://www.flickr.com/photos/9960539@N07/13812273935/

More to come ...

Greg

Standard MPR Rod Launch

In contrast to the laser straight launches using Micro Buttons and OpenBeam, here is my oldest launching his Estes Ventris on an AeroTech F40.



Video Link:

https://www.flickr.com/photos/9960539@N07/13812300953/

More to come ...

Greg

Greg:
Are You testing Micro (2-56 Screw) or Mini (4-40 Screw) buttons. It was my understanding 2-56 binder head screws Did not fit the 15mm Square "OpenBeam" Rails but would work well with Mini 4-40 Screw buttons.

Just want to be sure we're not trying to compare Apples and Oranges.

Micromeister said:

Greg:
Are You testing Micro (2-56 Screw) or Mini (4-40 Screw) buttons. It was my understanding 2-56 binder head screws Did not fit the 15mm Square "OpenBeam" Rails but would work well with Mini 4-40 Screw buttons.

Just want to be sure we're not trying to compare Apples and Oranges.

Click to expand...

Micromeister,

The supplied screws with the Micro Buttons are 2-56, and fit inside the collar or "web" area of the button. I did not do a test of Nylon 4-40 screw/nuts that would act like a button, but I hope to in the future. As an aside, no adhesive (epoxy or CA) or Loctite was used to secure the buttons to the plywood. They are held on solely by the threads of the screw interacting with the tapped plywood.

The purpose of this series of tests was to beta test the Micro Buttons for Randy and report my findings.

Greg

Micromeister said:

Greg: I'm still wondering why you think you need to join two rails? talk about excessive!

Click to expand...

Per the information in this document, it wasn't excessive at all.

https://www.apogeerockets.com/Wind_Caused_Instability

Greg

GregGleason said:

Per the information in this document, it wasn't excessive at all.

https://www.apogeerockets.com/Wind_Caused_Instability

Greg

Click to expand...

Pretty Nifty Button sled by the way.

6ft or better is very True for MPR particularly on windy days and it is very interesting to see these Micro 2-56 screw Buttons can work for some Mid power models. That Said It was my understanding the original intent for Micro Buttons was for MODEL Rockets from Micro-Maxx to about 1lb. where a single 35.5" or 48" beam are more then sufficient in winds to 20mph.

I was never very happy with the Old ESTES two piece C-Rail because of the ware caused by slight misalignment at the joint. I'd be just as suspect of joining two Aluminum rails of any diameter. While these extruded aluminum channels are pretty close in tolerance there is Always dimensional variance within each piece not to mention extrusions form different billets.

Test Rocket 3

The last test of the day would be on a Wildman Wild Child kit, that I have appropriately called “Test Round”. Originally I wanted to fly on a CTI E75 VMax, but there was some question about the delay, so I put the AeroTech 24/40 RMS case to use again and opted for a less radical E28-4T. The launch weight came in at 547 grams (19.925 oz or 1.2 lbs). While not as radical E75, it still should have a respectable “I’m outta here” factor. The heavier rocket with the higher impulse will be the high watermark for the stress test. If it can pass this test, I will have the confidence that it will be able to fly anything “G” impulse and under. If that turns out to be the case, I should be able to fly any of my LPR/MPR birds using rail when properly outfitted, if I so choose. That is my bottom line goal.

Again, the winds were a bit stiff and the rail wanted to tip over, so I steadied the rail until right before the countdown. The button was pushed and “Test Round” was off.



Video Link:

https://www.flickr.com/photos/9960539@N07/13835148913/

More to come ...

Greg

Test Rocket 3 Rail Button Detail

Since masking tape worked well on Test Rocket 2, I tried to continue the success track by applying it on the last test. This time I was a bit more purposeful and neat about the placement of the tape. I burnished the tape down with the non-blade end of an X-Acto knife.



Greg

Conclusion

I am happy with the results of the test. Not only can the Micro Buttons handle LPR, they can likely cover most of the spectrum of MPR as well.

I can recommend the Micro Buttons as a valid alternative to launch lugs. If there is one criticism, it is that the “web” portion is a bit long for my tastes. I might trim mine in the future so they fit the rail with less slop, but I wanted to test the buttons “stock” so others might know what to expect.

All of the test flights went straight up, in spite of winds at the limits of flying.
One thing I need to do is revamp the launcher base, so it is more wind resisistant. I also need to come up with a better join mechanism for the rail. While it is an acceptable temporary fix, I need to look into something longer term.



A special thanks to Randy of Rail-Buttons.com for giving me opportunity to beta test the Micro Rail buttons.

Greg

Thanks for the thread Greg.

Randy sent me some micro-buttons too, which I hope to do some work with this weekend. Unlike your approach, I intend to mount the buttons "permanently" (ie, no sled). I am hoping to test a set of them on my USR AeroRoc, probably with an F or G.

Jason

Many thanks to Greg and John for the testing they have already done on the microbuttons. Being able to test on a day where wind would have really been a factor on a rod added to the validity of the test.

To address one of the concerns, I've looked into having the spacer part of the buttons custom made to half of the length it currently is which will be 1.5mm or about .06". I've sent out some additional buttons to both John and Greg to see if they can cut trim them down to that size and see if the fit is better. I've done the same and it looks much better, but haven't had a chance to fly one that way yet. If all goes well, I will pursue moving forward with the custom part. BTW, the tooling charge isn't cheap and the minimum run would be 25,000 pieces, so I would like to make sure we get it right the first time and appreciate the patience to get it right.

If there are others with the makerbeam or openbeam that would like to test as well, let em know and I can get some out to you as well.

I finally got a chance to try this out today. I put a couple of the micro buttons on a Quest PayloaderOne last night (unmodified except for shortening the screws). Two flights today were arrow straight off the 900 mm Makerbeam - though the conditions were pretty benign and so not much of a challenge for the arrangement. I will be trying some more as soon as I decide which other rocket to equip with the other pair of micro buttons Randy sent me.

To mount the MakerBeam I went really simple. I simply drilled out one of the threaded ends to 1/8 inch and then epoxied in a short length of Estes 1/8 inch launch rod. This was then inserted in our club rack just like any other 1/8 inch rod, but I let the end of the beam rest on the ceramic tile base. I'm still trying to figure out the best arrangement for a blast deflector on my personal GSE...but I will come up with something.

Added: I will say that the one flight I got good altimeter data from was considerably lower than usual for this model (on the order of 20%) on the same motor and carrying the same payload (a PerfectFlite Pnut). I wouldn't think that the buttons added that much drag (I left the launch lug on). But I also noticed loading/unloading for the picture that if the model is canted such that the axis of the button is at an angle to the slot it can bind up pretty good. If the distance between the screw head and the flange on the spacer was much closer to the actual thickness of the metal forming the slot in the beam, this could not happen. So I will add my voice to those who say that a shorter shank on the spacer for the micro buttons would be a good idea.

I will shorten the shanks on the other pair of buttons before installation on another model. I'm thinking about putting them on my well-worn Nova Payloader (which had its 57th flight today) but I also am thinking of finding a model that would benefit more from the straighter, more rigid guide. The NP has plenty of stability margin.

OK, adding to this thread rather than starting my own.

Randy sent me two sets of the 2-56 microbuttons that fit the Makerbeam. I wanted to test them at both the low and high extremes of how I would envision most fliers might use them. So I prepped out my Estes Astron Elliptic with a set of the buttons by simply drilling a small hole for each, adding a drop of ca glue, and screwing the buttons down into place. Motor of choice as the mighty 1/2A3-2T. The second test mule was my USR Aero-Roc with buttons secured the same way, which as you can see in the pics is definitely as big as you would want to go with the 900mm length of Makerbeam. The plan was to fly the Aero-Roc with a succession of motors, from mild to wild.

Test flights were conducted on a gusty day with winds 6-12 MPH. First up was the Elliptic...nice straight flight. I had been concerned about a little bit of a binding feel as I placed the rocket on the rail but is sure did seem to fly normally.

Next was my Aero-Roc with an AeroTech E20-7. Nice straight flight, but a bit of a walk to recover with wind drift. So for the next flight I tilted the rail to probably 8 degrees or so into the wind. I am through and through an AeroTech guy, but had recently ended up trading another rocketeer for a CTI F240 and that was used for flight #2 on the Aero-Roc. Lift-off was more like an explosion (bear in mind that the Aero-Roc wieighs about 14 oz loaded and that F240 is pumping out 50 ish pounds of thrust). Straight, high flight. This motor is really close to a miniature high power motor and the stresses upon the rail/buttons encountered on this flight would be very comparable to say a H238 in a similar rocket. The only issue I saw is that upon recover the buttons had backed off a little. I straightened them back out, good as new.

Next motor was an AeroTech E11 (again in the Aero-Roc), which is on the extreme low end for this rocket. It started billowing smoke immediately but did not come up to pressure for a good 3 seconds. When it did, it flew in a pretty lazy arch. Recovery was OK, thanks the the 3 sec delay, but this most definitely would have been better with two lengths of the rail joined together.

Last flight was with Estes F15. Again, it arched pretty good, but keep in mind that the thrust to weight was pretty low and the angle of attack into the wind was pretty high. Rocket recovered nominally.

To sum it up - I like these microbuttons. They obviously have a wide range of applications looking at both model size and ranges of thrust. While I was happy with complete lack of rod whip (the biggest advantage of rails IMO), it is obvious to me that on the lower thrust to weight lift-offs a longer rail is needed. Oh one more thing...they look a lot cleaner than lugs.

rail-buttons said:

Many thanks to Greg and John for the testing they have already done on the microbuttons. Being able to test on a day where wind would have really been a factor on a rod added to the validity of the test.

To address one of the concerns, I've looked into having the spacer part of the buttons custom made to half of the length it currently is which will be 1.5mm or about .06". I've sent out some additional buttons to both John and Greg to see if they can cut trim them down to that size and see if the fit is better. I've done the same and it looks much better, but haven't had a chance to fly one that way yet. If all goes well, I will pursue moving forward with the custom part. BTW, the tooling charge isn't cheap and the minimum run would be 25,000 pieces, so I would like to make sure we get it right the first time and appreciate the patience to get it right.

If there are others with the makerbeam or openbeam that would like to test as well, let em know and I can get some out to you as well.

Click to expand...

I came up with a quick way to trim the beta buttons...check here in the main thread (#322)

I got the other pair (trimmed down in a rather more haphazard fashion) on my well-worn Nova Payloader tonight. It's supposed to be breezy to over-the-limit windy at the launch I'm going to this weekend, so it should be a good test environment.

anybody got an idea of what practical size limit these little guys could handle? I am tempted to stick some on my Leviathan but my Openbeam rails are 1000mm length (longest I can find)...I am cogitating on how to join two of these bad boys to make a 6 ft rail for PSII-sized rockets...Greg did you say you joined yours end-to-end?

rocketguy101 said:

anybody got an idea of what practical size limit these little guys could handle? I am tempted to stick some on my Leviathan but my Openbeam rails are 1000mm length (longest I can find)...I am cogitating on how to join two of these bad boys to make a 6 ft rail for PSII-sized rockets...Greg did you say you joined yours end-to-end?

Click to expand...

David,

I think OpenBeam could take up to a baby "H" impulse. It looked like it wasn't breaking a sweat with the "E" impulse motors.

Regarding the joining the rails, I cobbled together a "quick and dirty" solution by placing 2 x 5/16's brass rods into the slots as guides surrounded by a "C" sectioned piece of PVC pipe. It worked "OK", but I spent some time last night working on another join solution with some cheap angled aluminum and M5 bolts and wingnuts. I hope to mill some today to see how they fit. If they work great, then I will report back.

The nice thing is that the OpenBeam rail looks like they run with pretty tight tolerances, which lends itself to a precision join.

Greg

rocketguy101 said:

anybody got an idea of what practical size limit these little guys could handle? I am tempted to stick some on my Leviathan but my Openbeam rails are 1000mm length (longest I can find)...I am cogitating on how to join two of these bad boys to make a 6 ft rail for PSII-sized rockets...Greg did you say you joined yours end-to-end?

Click to expand...

Makerbeam will be coming out with 1500mm rails in July.

rail-buttons said:

Makerbeam will be coming out with 1500mm rails in July.

Click to expand...

I saw that in your other thread...thats the 10mm rail, isn't it?

rocketguy101 said:

I saw that in your other thread...thats the 10mm rail, isn't it?

Click to expand...

yes.

OK here is what I am thinking for my Openbeam pad...starting with the tilt head I designed a couple years ago, I am going to make a longer support and attach the beam with a couple screws and add some support guides. I have a good buddy w/ sheet metal equipment that can make the blast deflector

View attachment MPR_VerticalBlock_RailConfig.PDF

I built two rockets to test the micro buttons with. I figure the smallest I will fly would be an Alpha-class. The other is an Estes Monarch, which represents a medium-sized LPR. The rail buttons look really good on these birds!!! I first poked a small hole with a compass point, put a drop of CA in the hole, and let it wick into the tube. After the CA hardened, I drilled a #46 hole which is a little smaller than the screw OD. I threaded the rail button in place, removed it, put a drop of 5 min epoxy in the hole and re-tightened the rail button screw. On the Alpha, the lower rail button is going into the centering ring, just like the big boys

My launcher is complete, so if the weather holds out Saturday, I will fly these!

If the Openbeam rail was 4 ft, I would stick a couple of these micro buttons on my Leviathan and fly it too, but with an effective length of 36" or so, I don't want to chance it.