L3 Project Build Thread - Performance Rocketry Competitor 4

I hope anyone attempting an L3 doesn't find drilling three holes in a line challenging.

Guidance ends when the penultimate button leaves the rail.
Two buttons down low can extend guidance as long as possible, but then there is a lot of torque on the buttons as the rocket sits on the pad "twisting" in the wind.
A third button further forward helps relieve this stress.

neond7 said:

I agree that three buttons provide better guidance. As soon as the first rail button comes off the rail, that rear button isn't doing much.....

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Exactly - as soon as you're down to one button on the rail you lose guidance.

chuck5395 said:

Looking good Wilson. At least one of us is moving forward with our planned winter projects.

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Thank you Chuck! What's your winter project gong to be?

neond7 said:

As far as installation technique for the third button, its pretty easy. I just use a long piece of angle iron and butt it up against the upper and lower buttons. Then I place the third button against the angle iron and hold it in place while I drill the pilot hole. Since all three buttons are physically aligned with the angle iron, they will be straight and not bind. Trying to eyeball them in place would be asking for trouble.

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I use that exact same method, with the angle iron.

FredA said:

I hope anyone attempting an L3 doesn't find drilling three holes in a line challenging.

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Good point!

FredA said:

I hope anyone attempting an L3 doesn't find drilling three holes in a line challenging.

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I don't know Fred, maybe they documented that the holes might not be lined up.... Wouldn't make it OK? :lol:

AlnessW said:

Thank you Chuck! What's your winter project gong to be?

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I am working on a 4" X-Plane SST.
https://www.rocketryforum.com/showthread.php?60234-X-Plane-SST-in-BlueTube

I also have plans for a night flyer and I'm actively working on acquiring two more kits (one of which is a Binder Design Lighting-Bolt).

maybe they documented that the holes might not be lined up.... Wouldn't make it OK?

Chuck you crack me up.
Yes -- buttons anywhere should be fine if documented....

Wilson - don't fly off of Quadzilla. Use one of our towers with the supported rail -- much more vertical flight.

I suppose I didn't phrase my question properly... Wildman kits, to the best of my knowledge, dont include rail buttons, or a way to attach them. How are you attaching the buttons and how will you ensure the buttons are square to the tube. With weld nuts, it's generally not a problem, but if you're drilling into wood, what's your setup to ensure you don't drill at an angle?

Do not use 3 buttons.

2 points define a line. You can't mis-align 2 buttons. You can easily mis-align 3. Two 1010 buttons are plenty for a C4. I have flown mine a couple dozen times with a few L and M flights - two 1010 buttons. Put them both down low on your booster. No problem. Back them with nuts if you can - that makes for a solid, straight attachment.

--Lance.

You can't mis-align 2 buttons.

What???
Two points form a line - but is it the line you need????

You NEED the guidance aligned with the rocket....no other alignment will do...or you get the "Gambler Effect" of a corkscrew off the pad.
Once you draw the PROPER line, how hard is it to drill three holes instead of two???

TNuts work well for installing railbuttons.
The tines are just about a wall thickness short of the threaded body.
Insert them from behind with a good dollop of epoxy on the tines and then pulled into position with a screw from the outside.

Yes, I have plenty of rockets with only two buttons -- but that's because there were reasons for only two (like no mounting spot for the third) -- for a rocket without such limitations, I'll always add a third button.

If you can't get the proper line drawn or drill three holes on that line, I suggest you back away from the rocket workbench.....

FredA said:

You can't mis-align 2 buttons.

What???
Two points form a line - but is it the line you need????

You NEED the guidance aligned with the rocket....no other alignment will do...or you get the "Gambler Effect" of a corkscrew off the pad.
Once you draw the PROPER line, how hard is it to drill three holes instead of two???

TNuts work well for installing railbuttons.
The tines are just about a wall thickness short of the threaded body.
Insert them from behind with a good dollop of epoxy on the tines and then pulled into position with a screw from the outside.

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Yes, but you have a margin of error to work with (whereas with 3 buttons you don't). In my experience (granted, with much smaller rockets), the buttons don't need to be 100% in line with the rocket to be effective. Usually I just eyeball them (though I do have a pretty good eye for that stuff... I am able to divide a long straight line in half just by eyeballing it to within + or - 1mm)

FredA said:

Yes, I have plenty of rockets with only two buttons -- but that's because there were reasons for only two (like no mounting spot for the third) -- for a rocket without such limitations, I'll always add a third button.

If you can't get the proper line drawn or drill three holes on that line, I suggest you back away from the rocket workbench.....

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Fred, You do what you think you need to do, but I guarantee you you are in the deeply out-numbered minority. It is easy to draw the proper line but much more difficult to get 3 buttons installed at exactly the correct angle. Most people are going to have to hand-drill the holes, introducing lack of precision. I'm not a fine craftsman, why would I introduce that frustration when it is completely unnecessary?

I have seen flyers remove that third button at the field, but never install a third one.

--Lance.

I have often been at odds with Fred's opinions, especially with regard to redundant electronics (as a former Reliability Engineer) but with the three buttons, I'm OK. I have about a half dozen rockets with three buttons. I will use a third button if I have a large, heavier (typically 7.5" dia and above) rocket and the CR's available for attachment are low on the airframe. I also will use three buttons on two-stage builds when I have a sustainer that I want to fly independently. I have also used three buttons on a 4" rocket that had a primo paint job (once you get those bottom two buttons inserted in the rail you have far less chance of scratching / smudging paint on the final higher button). I have never had an issue with alignment of three buttons, in fact it is quite easy.

I have 2 large rockets with 3 rail buttons and have never had a problem. I seen flyers use 2 buttons that have the buttons so far out of line they can barley get the rocket on the rail. Just need to do a good job putting the 3 buttons on.

chuck5395 said:

I am working on a 4" X-Plane SST.
https://www.rocketryforum.com/showthread.php?60234-X-Plane-SST-in-BlueTube

I also have plans for a night flyer and I'm actively working on acquiring two more kits (one of which is a Binder Design Lighting-Bolt).

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Very cool! I'm thinking about one of the new Binder Kits as well, with Mike Fisher's Holiday Special and all...

FredA said:

Wilson - don't fly off of Quadzilla. Use one of our towers with the supported rail -- much more vertical flight.

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Roger - David has also offered me the use of his tower. Much appreciated!

emckee said:

I suppose I didn't phrase my question properly... Wildman kits, to the best of my knowledge, dont include rail buttons, or a way to attach them. How are you attaching the buttons and how will you ensure the buttons are square to the tube. With weld nuts, it's generally not a problem, but if you're drilling into wood, what's your setup to ensure you don't drill at an angle?

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You are correct - Wildman kits do not include rail buttons, in fact all that's included are the fiberglass parts. See the photo I took early on of the contents of the box. I am attaching the buttons using the T-Nut method that Fred described. This way, they are secure and reinforced from the inside. I would also like to echo his comment of how drilling 3 holes in a straight line should not be that difficult.

Building is on hold for now while I'm visiting family in Tahoe for Christmas. Will post more photos as soon as I return and progress resumes!

Forged eyebolts installed on the av-bay lids. Way overpriced, but worth the extra strength.


Booster section cut to length.


Test-fitting the rail buttons using Fred's T-Nut attachment system.


Making sure all 3 buttons are aligned. (Note, to all concerned: It wasn't that difficult.)

Great build thread. .

Since the top button is so close to the top of the body tube, won't it interfere with the av-bay coupler?

neond7 said:

Great build thread. .

Since the top button is so close to the top of the body tube, won't it interfere with the av-bay coupler?

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Thank you Jeff. Yes, what I'll need to do with the top button is bend the T-Nut tines in a little ways, and install the button right through the anti-zipper coupler. Slightly more work, but I wanted the top and middle buttons to be further apart if possible. (The photo I posted was just the dry-fit, nothing has been glued together yet.)

"Box of goodies" in the mail from Jack at What's Up Hobbies. SkyAngle Cert-3 drogue chute, shockcord, and the anti-zipper coupler.


Assembled drogue compartment with av-bay secured via sheet metal screws.


Von Karmon nosecone with coupler glued in place. Looking more and more like a rocket by the day!

More photos will follow soon. Been setting fins this weekend!

Setting the fins. Apparently no one over at Wildman thought it would be a good idea to make sure the fin slots were wide enough to accept the fins. They weren't. This meant lots and lots of sanding to get them to fit. If I had a functional Dremel, I would have just widened the fin slots a bit...


All 3 fins attached. Now it really looks like a rocket! Next up - fillets and expanding foam.

Looks good .. cant wait to see the foamed up pics

L3 for the win !

Kenny

Sent from my SPH-L710 using Rocketry Forum mobile app

KenRico said:

Looks good .. cant wait to see the foamed up pics

L3 for the win !

Kenny

Sent from my SPH-L710 using Rocketry Forum mobile app

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Thank you Kenny! Yep, hoping to pour the foam this weekend. Can't wait for launch day, either!

AlnessW said:

Thank you Kenny! Yep, hoping to pour the foam this weekend. Can't wait for launch day, either!

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Will you be doing internal fillets as well?

Looking good. One question though, are you worried about having the recovery system get hung up on the t-nut holding the rail button at all? Is that going to be behind the anti zipper bulkplate?

I only use 2 on most of my rockets.
My only exception for using three would be; a 2 stage rocket.
Thus topic has been debated before nor too long ago......


JD

rocketgeek101 said:

Will you be doing internal fillets as well?

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Yes, internal fillets and then expanding foam.

RocketGeekInFL said:

Looking good. One question though, are you worried about having the recovery system get hung up on the t-nut holding the rail button at all? Is that going to be behind the anti zipper bulkplate?

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Correct, the forward-most rail button will be behind the anti-zipper bulkplate/coupler.

I will agree that 3 buttons can be a challange and the way I do 3 buttons now is to have the top one on a section of the body that can be twisted to align with the rail and the lower 2 buttons on the lower unit. In fact I had my 7.5"dia 10' tall L3 cert rocket only with 2 buttons set up on two different sections that I could twist align when sliding it on the rail.
Just my 2.5 cents.
Good Luck with your L3 fight.

Anti-zipper coupler epoxied in place.

Did the first set of internal fillets, as well. With the low viscosity of this epoxy, it flows quite nicely down the length of the fins when poured from the aft end.

It's looking good Wilson!

chuck5395 said:

It's looking good Wilson!

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Thanks Chuck! How's that blue tube rocket of yours coming along?

AlnessW said:

Thanks Chuck! How's that blue tube rocket of yours coming along?

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Sadly it is not moving along at all. I hope February will see me spending more time working on my rockets.

chuck5395 said:

Sadly it is not moving along at all. I hope February will see me spending more time working on my rockets.

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I hope so too!

Did the last set of internal fillets today. Oh yeah, I also need to start thinking about a clever name for this vehicle...

AlnessW said:

I hope so too!

Did the last set of internal fillets today. Oh yeah, I also need to start thinking about a clever name for this vehicle...

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How about naming it "Fred"?