Rail Buttons 2 or 3?

Okay I am building my L3 rocket and have been today to use 3 buttons by some people and 2 by others. What is your take on this? I usually use 3 (2 on the booster and 1 around the e-bay area. If I do 3 they would be 1" from bottom 15" from bottom and 44" from bottom and the overall length of the rocket is 124" and should be around 40 pounds loaded on pad.

Use what you're used to and comfortable with. I normally use 2 but that is not based on any fact, just the way I started doing it and it makes sense to me. Doesn't make it more right or wrong than using 3.

-Aaron

Two is sufficient...getting three to line up with out binding on the rail can be a headache...

Johnnie

I generally use 3 rail buttons. Mainly so that you can increase the effective length of the rail. I pull up 2" from the bottom of the rocket, then pull another 2" from that and put a button at each location. Then I put a button as high up as I can on the booster section - generally 18-24" from the bottom of the rocket.

Edward

2

I always install the buttons into the centering rings and use either 2 or 3 depending on the number of rings. One always goes goes into the aft centering ring, one in the next centering ring forward, and a final one, if possible, in the furthest forward centering ring. The reason for the button in the aft centering ring is that I like to keep control of the rocket with the rail buttons as long as possible. On the other hand the third button is added to improve stability while the rocket is sitting on the rail in windy conditions.

krsconstruction said:

Okay I am building my L3 rocket and have been today to use 3 buttons by some people and 2 by others. What is your take on this? I usually use 3 (2 on the booster and 1 around the e-bay area. If I do 3 they would be 1" from bottom 15" from bottom and 44" from bottom and the overall length of the rocket is 124" and should be around 40 pounds loaded on pad.

Click to expand...

I like 3. But I put the second one about 8 to 10" up from the first. When the two rear buttons are a little closer together, there is less tendency to bind on the rail.

I tend to use 2, but use what you are most comfortable with and hasve used in the past. That is the most likely to work well for you.

A team that I'm involved with resently built a 12+ ft. Coyote rocket and we used 2, she flow beautifully at SOUTHERN THUNDER. We are adding the booster which will make it well over 22ft. and I'm not sure the number we will use or what other creative ideas we might come up with, for that size bird.

IDEAS always welcome for our project.

I agree with those above that say, use what you have had the most success with.

Good Luck
IRV

I use 2 cuz thats what I was told. I believe proper attachment is more important than number--I like barrel nuts epoxied into the CR's. I recently put up a 14' 2 stage rocket on 2 that were only about 3.5' apart on the aft end of the booster. That to me seemed a bit dicey as the nose cone was well above the rail, but in the end worked flawlessly. Since they were different diameter rockets there was no way to pin the sustainer to the rail, but I would have preferred it that way. In these cases I would think three are preferable.

Few answers are universal. Just because something worked for one rocket does not mean it is the appropriate solution for another rocket.

What size buttons? 1010, 1515, Unistruct?

What is the weight distribution of the rocket? (Is it top heavy?) (How far is CG ahead of CP?)

Diameter of rocket?

I will tell you what my level 3 adviser told me before I started building. "don't do anything different from what you are already doing."

Except of course build it big enough for the M motor your using.

In other words, if you have been using 2, keep doing it, if 3 keep doing that.

Thanks everyone for your comments and advice. I will be staying with what I did on my other projects and use 3 buttons. I have had good luck with it in the past so why change a good thing.

Larry_Pollack said:

I will tell you what my level 3 adviser told me before I started building. "don't do anything different from what you are already doing."

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I think that is terrible advise when moving from one level to another, unless your advisor ment that you were doing a terrific job of analysing situations and applying appropriate solutions. If that is not what your advisor ment then the advise is equivalent to recommending the use of 1/2" rod for a 50 pound rocket because that's what you have always used and therefore you should continue to do so.

I will be staying with what I did on my other projects and use 3 buttons.

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If the top button will be on a rotateable section, then it can easily be aligned.

snowman2 said:

I think that is terrible advise when moving from one level to another, unless your advisor ment that you were doing a terrific job of analysing situations and applying appropriate solutions. If that is not what your advisor ment then the advise is equivalent to recommending the use of 1/2" rod for a 50 pound rocket because that's what you have always used and therefore you should continue to do so.




If the top button will be on a rotateable section, then it can easily be aligned.

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Once again, people cut and paste and than take what was posted out of context and/or leap to some odd conclusion.

Did you read my entire post? Had you done that you would have said that I was applying that advice to his question. I suggested to continue to use the same number he already uses.

Why do you think somone would tell me to keep doing what I am already doing but make it the appropriate size, if I was *not* using sound construction and procedures? Dont you think he would suggest changes if I wasent?

Also, please, when quoting one person, dont add in another person's quote without making it clear they are different posts. I never posted

"I will be staying with what I did on my other projects and use 3 buttons. "

The way you quoted it makes it look like I did.

My L3CC recommends using three rail buttons. Two which are closer together because the centering rings are usually closer together. The other further up the rocket. That way, it gives the rocket several more feet of travel before only one button is guiding the rocket.

n3tjm said:

My L3CC recommends using three rail buttons. Two which are closer together because the centering rings are usually closer together. The other further up the rocket. That way, it gives the rocket several more feet of travel before only one button is guiding the rocket.

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Everyone I know who uses two sets them into the bottom two rings. This usually means they are pretty low on the rocket. Than you just make sure that the rail is long enough so that you have aerodynamic stability before the top button clears the top.

Three works fine, my own opinion is that its one extra button.

I also think, dont change what your doing if it works for you. What I mean is...if you use two, and that works, why change. or if you use three and that works, why change.

Or...if its a kit rocket, do what the kit manufacturer says to do.

Heada hit the nail on the head do what your comfortable with....2 is fine and with three they must be "perfectly" aligned or you can as others have said have binding problems...i'd go with 2...my 2 cents...Good luck!