3' vs 4' launch rod

[bobbyg23]

Is there any benefit or negative to using a 4' launch rod over a 3' launch rod?

 

[Daddyisabar]

Longer better, especially for oddrocs.

 

[KennB]

The longer rod will give you a higher velocity before loss of guidance. On the down side, the longer rod will tend to whip more with a heavier, larger diameter rocket.

 

[bobbyg23]

The longer rod will give you a higher velocity before loss of guidance. On the down side, the longer rod will tend to whip more with a heavier, larger diameter rocket.

I was wondering about rod whip.

 

[GregGleason]

Yes. It's slightly heavier. And has a longer arm to whip when a bending moment is applied. The problem is more pronounced on larger diameter rockets (nozzle to rod distance: closer is better). Tool steel is a bit stiffer than stainless and carbon steel (modulus of elasticity). Tool steels and carbon steels have less corrosion resistance than stainless steels (although stainless steels can rust, albeit at a much reduced rate).

If there is no rod whip, then the 4' is better than the 3'.

Greg

 

[DaHabes]

I use 1010 rail buttons for all MPR and HPR as well as LPR clusters (example - NCR Cluster Duck is 1x24mm and 6x18mm). If you want low and slow, realistic takeoffs, you need both length and rigidity. Only a rail will give you both. Joining multiple short rails give you many options. I have one 6' and two 4' rail sections, giving me rail options of 6', 8', 10' and 14'. Sim it out, find how long of a rail you need, join sections. Just like the erector set I had as a kid.

 

[bobbyg23]

I use 1010 rail buttons for all MPR and HPR as well as LPR clusters (example - NCR Cluster Duck is 1x24mm and 6x18mm). If you want low and slow, realistic takeoffs, you need both length and rigidity. Only a rail will give you both. Joining multiple short rails give you many options. I have one 6' and two 4' rail sections, giving me rail options of 6', 8', 10' and 14'. Sim it out, find how long of a rail you need, join sections. Just like the erector set I had as a kid.

I only have lpr right now so I just use a rod. Maybe someday I will step up to a rail.

 

[neil_w]

I do like 3’ for 1/8”, 4’ for 3/16” (longer heavier rockets).

 

[bobbyg23]

I do like 3’ for 1/8”, 4’ for 3/16” (longer heavier rockets).

Perfect. I have 4' in the 3/16 size. I will go with that and leave my 1/8" pad a 3 footer. That is what I was thinking, just wanted to confirm.

 

[neil_w]

Longer better, especially for oddrocs.

Sometimes. Short rods are good for spinning saucers.

 

[CalebJ]

What's involved in aligning sections of rail - is it a pain to get it precise enough for the guide/button to travel through clearly?

 

[GregGleason]

I use OpenBeam 1515 for modrocs. I have a 6' rail. Amazing straight flights. I use small nylon screws as the rail buttons. It is 15mm x 15mm.

https://www.makerbeam.com/openbeam/openbeam-15x15mm-profile-lengths-anodised-in-black/

Greg

 

[GregGleason]

Here is a liftoff shot of my rail rig.

 

[Daddyisabar]

Sometimes. Short rods are good for spinning saucers.

And then there are some you light with a fuse that need no rod at all. But we may not speak of those here.

 

[crossfire]

What's involved in aligning sections of rail - is it a pain to get it precise enough for the guide/button to travel through clearly?

It's not hard at all

 

[crossfire]

My 1515 rail has 3 plates that slid in the 3 slots not being used. You just slide the 3 plates 1/2 way on the 2 rail sections and tighten screws. As screws tighten the rail self aligns. It's very easy. Where ever you buy the rail they should sell some type of rail extension plates

 

[Ez2cDave]

I use OpenBeam 1515 for modrocs. I have a 6' rail. Amazing straight flights. I use small nylon screws as the rail buttons. It is 15mm x 15mm.

https://www.makerbeam.com/openbeam/openbeam-15x15mm-profile-lengths-anodised-in-black/

Greg

https://www.makerbeam.com/2000mm-1p-black-makerbeamxl-15mmx15mm.html

 

[NateB]

And then there are some you light with a fuse that need no rod at all. But we may not speak of those here.

I'm working in one that we can talk about here. I'll start to share details on the small prototype soon. I have an idea for launching that should be RSO approved, if not I'll work out the details with D engines in a park.

 

[bobbyg23]

I tried the 4' rod today and it worked great!

 

[neil_w]

Outstanding. Were those C11s again?

 

[bobbyg23]

Outstanding. Were those C11s again?

Yup. That is all I have right now. I need some D12-5's to try out.

 

[Ez2cDave]

And then there are some you light with a fuse that need no rod at all. But we may not speak of those here.

Because they come from "C-h-i-n-a" ???

LOL !

Dave F.

 

[Daddyisabar]

Because they come from "C-h-i-n-a" ???

LOL !

Dave F.

With the current anti CHICOM environment that gag restriction could be lifted. BUT they are still illegal in most jurisdictions so the law and order gag would still apply, unless we are in THE GREAT STATE OF WYOMING! Additionally, anything leaving the ground without a rod or rail is not family friendly on this forum. Spinning things are also very scary.

 

[Ez2cDave]

With the current anti CHICOM environment that gag restriction could be lifted. BUT they are still illegal in most jurisdictions so the law and order gag would still apply, unless we are in THE GREAT STATE OF WYOMING! Additionally, anything leaving the ground without a rod or rail is not family friendly on this forum. Spinning things are also very scary.

What if we "tower launched" them and used Estes "Starters" ?

Some flights could qualify as "Featherweight Recovery".

"Spinning things" could be okay, too, since we fly "Mono-copters".

Dave F.

 

[BABAR]

I tried the 4' rod today and it worked great!

Perfect small field rocket flight!

 

[Daddyisabar]

What if we "tower launched" them and used Estes "Starters" ?

Some flights could qualify as "Featherweight Recovery".

"Spinning things" could be okay, too, since we fly "Mono-copters".

Dave F.

I'd like to see a soaring diamond on some starters!

 

[Ez2cDave]

I'd like to see a soaring diamond on some starters!

We might need to dip them . . . LOL !

Dave F.