Lakeroadster's "Level One"

Daddyisabar

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Golly kids, if a Quarter inch is the biggest rod you have seen in the upper right and left, then it is time to road trip to the center to witness some Half inch rod, model rocketry - oddroc porn. Like you were told you will go blind, but it is worth it.
20210604_091823.jpg
Yes Mr. RSO, rail buttons won't work on this one.
20210807_100755.jpg
Your level one cert rocket is too complex to fly off the god given rail? Oopsie! Darlin' we're gonna have to shut you down! ;)
 

boatgeek

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Golly kids, if a Quarter inch is the biggest rod you have seen in the upper right and left, then it is time to road trip to the center to witness some Half inch rod, model rocketry - oddroc porn. Like you were told you will go blind, but it is worth it.
View attachment 544634
Yes Mr. RSO, rail buttons won't work on this one.
View attachment 544635
Your level one cert rocket is too complex to fly off the god given rail? Oopsie! Darlin' we're gonna have to shut you down! ;)
MY EYES!!!!

I'm happy to see you wearing a hard hat and probable safety glasses. Those monstrosities deserve all of the precautions. :D
 

Daddyisabar

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MY EYES!!!!

I'm happy to see you wearing a hard hat and probable safety glasses. Those monstrosities deserve all of the precautions. :D
I was the one taking the picture with out protection. That dude is a Top Man looking over the thick rodded abomination.

Pitty the fool who tries to certify with a Cosmodrome Vostok. That beauty needs every bit of the stainless half inch rod. On mine no one noticed the 3/8" rod whip until we slowed down the video. I tried to blame the rod but I know it's my own dern fault. Got in the car and off to Grainger for a high quality, 1/2" stainless rod. Stand offs to multiple 1/2" lugs RULE! Fly the rockets you love and dread not.
 

boatgeek

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I was the one taking the picture with out protection. That dude is a Top Man looking over the thick rodded abomination.

Pitty the fool who tries to certify with a Cosmodrome Vostok. That beauty needs every bit of the stainless half inch rod. On mine no one noticed the 3/8" rod whip until we slowed down the video. I tried to blame the rod but I know it's my own dern fault. Got in the car and off to Grainger for a high quality, 1/2" stainless rod. Stand offs to multiple 1/2" lugs RULE! Fly the rockets you love and dread not.
Though I walk through the valley of the shadow of oddroc, I fear no rod whip, for thy standoffs and stainless comfort me.

[OK, that's enough threadjacking. Back to lakeroadster]
 

Daddyisabar

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The great thing about rear eject is that you could run nice stiff all thread rods through the body tube and make rail button stand offs...IF YER ROCKET WASN'T SO STUBBY! Still might work if they are far enough apart not to bind on the rail.
 

boatgeek

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So let's talk launch rails.
  • I'm assuming T-slotted framing rails?
  • What size?
  • Where's the best place to get them?
The normal standard is the 80/20 1010 section or any of equivalent knockoffs. You can get them from McMaster or your choice of online retailers. Definitely compare and contrast on shipping--that'll really bite you if you have to pay full rate. A 6-foot to 8-foot section is fine for MPR to L1 HPR.
 

jqavins

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Since you're planning to use this for a cert flight, doesn't that mean you'll be going against type and flying with a club? The club will have rail launchers, so you shouldn't need to buy your own.
 

Daddyisabar

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Since you're planning to use this for a cert flight, doesn't that mean you'll be going against type and flying with a club? The club will have rail launchers, so you shouldn't need to buy your own.
Do you have to be at a club (NAR) to certify? Or will a case of beer and two level one certified witnesses suffice? Tripoli is more strict.
 

jqavins

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I think it takes a Level 2 certified witness, but don't hold me to that. I've never heard of anyone doing it outside of a club launch, but maybe that's just me.
 

boatgeek

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Do you have to be at a club (NAR) to certify? Or will a case of beer and two level one certified witnesses suffice? Tripoli is more strict.

I think it takes a Level 2 certified witness, but don't hold me to that. I've never heard of anyone doing it outside of a club launch, but maybe that's just me.
NAR allows you to certify with a single L2 or L3 witness for an L1 cert. It doesn't have to be at a club launch--my L2 wasn't. It's just usually easier to get a launch site and waiver (if not Class 1) at an organized launch.
 

lakeroadster

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Since you're planning to use this for a cert flight, doesn't that mean you'll be going against type and flying with a club? The club will have rail launchers, so you shouldn't need to buy your own.

I want to create a cad file of the rail, so I can determine clearances and the feasibility of using one on this design. I think the conical fairings may result in the need for pretty long rail guides.

Sticking with the launch rod probably makes sense. But I really don't like the idea of a launch lug on the rocket that is bigger than 3/8" from an aesthetics perspective.

For me, making a CAD model gives me the visual to analyze the most logical path forward.

I'd kind of like to start using a rail anyway for these heavier rockets... plus the rail follows my Hell-For-Stout philosophy.
 
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lakeroadster

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NAR allows you to certify with a single L2 or L3 witness for an L1 cert. It doesn't have to be at a club launch--my L2 wasn't. It's just usually easier to get a launch site and waiver (if not Class 1) at an organized launch.
An H97-6 wouldn't require a waiver, correct? And the rocket only Apogee's at 1333 feet.
 

kalsow

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I want to create a cad file of the rail, so I can determine clearances and the feasibility of using one on this design. I think the conical fairings may result in the need for pretty long rail guides.

 

Sandy H.

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I want to create a cad file of the rail, so I can determine clearances and the feasibility of using one on this design. I think the conical fairings may result in the need for pretty long rail guides.

Sticking with the launch rod probably makes sense. But I really don't like the idea of a launch lug on the rocket that is bigger than 3/8" from an aesthetics perspective.

For me, making a CAD model gives me the visual to analyze the most logical path forward.

I'd kind of like to start using a rail anyway for these heavier rockets... plus the rail follows my Hell-For-Stout philosophy.
Maybe a custom fly-off rail guide? https://www.additiveaerospace.com/products/fly-away-rail-guides

Not sure if he would do a custom or not and I've never used one, but a solid guy for sure.

Sandy.
 

boatgeek

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Is it true that the only place I can fly motors with more power than a G80-7 is at a HP event, due to waivers?
No, it’s a little more complicated than that. You only need a waiver for >125 g propellant or >1500 g pad mass. There are a few baby H motors less than 125g. Most of the 3 grain CTI 29mm motors are but I don’t know about the AT options.
 

dhbarr

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No, it’s a little more complicated than that. You only need a waiver for >125 g propellant or >1500 g pad mass. There are a few baby H motors less than 125g. Most of the 3 grain CTI 29mm motors are but I don’t know about the AT options.

H238T
H128W
H210R
H180W
H220T

EDIT: should all be no-haz, <125g
 
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Daddyisabar

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Looks are the most important so I would go with a stubby rocket with a boatload of tiny fins and maybe some Greebles to hide a hefty launch lug. Just say: "Dude, it's way too wank to fit on the rail, but even if I have to use an old dude thick rod, I am maxing out the club site with a 38mm, 125g propellant AT H242 blue thunder! Maxing out the weight too with some nose weight. Dude, I am pushing the envelope to the max, soooo cool!" Kickin' that stubby into the air at break neck speed off the rod! Rear eject rules! Swing tested, Mother approved." With the 38mm case you can then load for bear at the High Power site. High power rocks!
 

jqavins

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No, it’s a little more complicated than that. You only need a waiver for >125 g propellant or >1500 g pad mass. There are a few baby H motors less than 125g. Most of the 3 grain CTI 29mm motors are but I don’t know about the AT options.
But note that does mean you'll need a waiver in place for that H97. From what I've read here, the waiver process does not require a club, but clubs that get them routinely have an easy time; they've climbed the learning curve, so you don't have to.

You'll also need a waiver for nearly all motors that you get access to with this certification accomplishment. So things will probably go a lot easier for you, now and in the future, if you join up.
 

Sandy H.

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Started making the basswood ply... not very exciting, but it is a means to the end.

View attachment 544789 View attachment 544790 View attachment 544791 View attachment 544792

With all the cool woodworking and interesting designs you do, I'm curious if you have a vacuum pump? I have made laminates similar to your method and also by putting the platens in a vacuum bag and pulling vacuum. The force with the bag was way more than the clamps and there was less warping of the ply. Both ways work fine, but for some reason, I like doing the bag method better. If you don't have a vacuum pump, though, it likely wouldn't be worth the cost for just this type of project. Once you had one, though, I bet you'd figure out some other cool methods and techniques to make more neat oddrocs. While I've never done it, I bet you could bend ply into shapes etc. with the help of vacuum and shaped platens.

Sandy.
 

lakeroadster

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With all the cool woodworking and interesting designs you do, I'm curious if you have a vacuum pump? I have made laminates similar to your method and also by putting the platens in a vacuum bag and pulling vacuum. The force with the bag was way more than the clamps and there was less warping of the ply. Both ways work fine, but for some reason, I like doing the bag method better. If you don't have a vacuum pump, though, it likely wouldn't be worth the cost for just this type of project. Once you had one, though, I bet you'd figure out some other cool methods and techniques to make more neat oddrocs. While I've never done it, I bet you could bend ply into shapes etc. with the help of vacuum and shaped platens.

Sandy.
Nope, no vacuum pump. I'm a low tech guy... and frugal.
 

lakeroadster

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I created a cad model of the t-slot. Since this is a rear eject, I'm going to plan on using the 5/16" launch rod, launch it with the G motor, and evaluate if that will be sufficient for the HP motor. I can always add rail buttons at a later date.

What's the hive opinion in regard to placement of rail buttons?

Level One Launch Dwg Sht 1 of 1.JPG
 
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boatgeek

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I created a cad model of the t-slot. Since this is a rear eject, I'm going to plan on using the 5/16" launch rod, launch it with the G motor, and evaluate if that will be sufficient for the HP motor. I can always add rail buttons at a later date.

What's the hive opinion in regard to placement of rail buttons?

View attachment 544828
The hive mind is a little like a kicked-over anthill on the topic of rail buttons. There is a distinct lack of consensus. Like makers of garam masala and adobo spice mixes (not to mention epoxy partisans on TRF), I feel like many people are absolutely convinced of the rightness of their position and the wrongness of everyone else's position, and none of them are really wrong.

I like to have the aft rail button as far aft as possible. I put the forward rail button a couple of body tube diameters forward of that*. My thinking is that I want them as low as possible to maximize the amount of time guided by the rail. There's more torque on the rail buttons this way, especially if there's some wind, but I've also never seen a rail button failure (I use weld nuts behind the buttons).

There are those who put the upper rail button at the CP and the lower one as low as possible. Others put the upper one at the CG.

Your rocket is so short I wouldn't have any heartburn with having the rail buttons as shown. Do make sure to update your OR sim with the rail/rod length as the distance between the top rail button and the top of the rail. That will give you more accurate rail exit velocities.

* Except when I forget to install the upper rail button before gluing in the upper centering ring. Then I put the upper rail button as far as I can reach down the tube.
 

Sandy H.

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My opinion matches @boatgeek pretty much. I think mounting the rear button/guide as low as practical is best and I personally mount the upper either close to the CG, or if it is a really long rocket, maybe a bit behind.

Given your rocket's length, I would put the bottom button as close to the back as possible and I would put the forward button near the CG, but still on the rocket body. I've never mounted one to the nosecone. I know CG drifts depending on motor selection, which might be why some people prefer using CP, not sure.

The fact that you're doing rear ejection might make all of the conventional methods completely moot, though. I assume you want the back-side of the inside of the rocket smooth so there is zero chance for snags. A rail button screw and nut might be bad in that case. . .I know some people use surface (conformal?) rail guides, but I have not, just buttons.

Sandy.
 
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