Launch Rod Compatability Question

[simbarat]

First time poster, this is a great forum. :jaw:

I know the answer I’m going to get here, but want to throw it out there anyway.

I have a Mantis launch pad and my largest build thus far has been a Loc Precision starburst which I have launched on it successfully twice (using two E9s both times) using the supplied 1/4” launch rod.

I just got a Loc 4-29ss (slightly bigger/heavier than a starburst) which to my surprise has a 1/2” launch lug. The mantis doesn’t support a rod any bigger than 1/4” so I’m in a bind. Is it ‘safe’ to either:
A) Epoxy the supplied 1/2" lug on the 4-29ss and send her up on the 1/4" rod I have
Or
B) Get one, better yet two 1/4” lugs and put it on the rocket using the rod I have
Or
C) Newb!... Your pushing the limits of the mantis with that rocket, you need a better launch system.

Thanks

If ‘C’ can someone direct me online where I can get some larger rods/launch systems.

 

[WillMarchant]

I think if you feel you need a launch rod larger than 1/4" then you are probably better off with a rail. See https://www.railbuttons.com/rb/faq.asp for more info.

 

[jadebox]

I just got a Loc 4-29ss (slightly bigger/heavier than a starburst) which to my surprise has a 1/2” launch lug. The mantis doesn’t support a rod any bigger than 1/4” so I’m in a bind. Is it ‘safe’ to either:
A) Epoxy the supplied 1/2" lug on the 4-29ss and send her up on the 1/4" rod I have
Or
B) Get one, better yet two 1/4” lugs and put it on the rocket using the rod I have
Or
C) Newb!... Your pushing the limits of the mantis with that rocket, you need a better launch system.

It's no so much the weight, but the power of the motors. You really need a sturdy launch pad to handle a cluster of four 29mm motors. And, you'll need a good launch controller that supplies enough current for four igniters.

Some combinations of motors for that rocket might take you into high-power territory where you'll need Level 1 certification to fly it and you'll need to notify the FAA when flying it.

So ... you might want to look into joining a local club. They will most likely have launch pads and controllers that will handle the larger rocket. Plus, they will handle everything with the FAA. And, you get to see a lot of other rockets fly.

As far as your own launch pad, making one isn't too hard. It can be as simple as driving a long launch rod into the ground and sliding a metal blast deflector over it. Search the web and you'll find lots of examples from ones made of PVC pipe to ones crafted from camera tripods.

You'll also find plans for launch controllers. A simple one powered by a car or motorcylce battery would be able to handle a cluster of four motors.

-- Roger

 

[H_Rocket]

a 4-29SS is somewhat larger and more intense a flight than a Starburst. It's 20" longer and uses 4 29mm mounts as opposed to 2 24mm mounts. I would not begin to fly that off a Mantis. In contrast to what Roger indicated the Mantis is not really appropriate for that rocket and the main reason is it is just way too heavy to allow for a stable CG that would prevent it from tipping over or bending the rod. I agree with Roger that a rail is a way better solution here. By the way - The 4-29SS absolutely rocks on 4 X G77R. I would like to try 4 x H165 at some point, and down the road 4 x I1200.

 

[simbarat]

Thanks everyone. I’ll investigate the rail option and any info on builds is appreciated.

I don’t foresee myself ever putting 4 Gs in the thing.

I have a portable car battery for juice and an aerotech controller.

 

[shreadvector]

https://www.doug79.com/stuff/HPR_metric9c.pdf

 

[H_Rocket]

I don’t foresee myself ever putting 4 Gs in the thing.

Oh c'mon -> no guts no glory!

It's only about a 2,500' flight. The 4-29SS is a rather draggy flyer.

 

[Zeus-cat]

You could check out this thread. A friend of mine used a Mantis to launch a 2 pound rocket with a G71 motor. He had some problems as the pad just wasn't beefy enough to handle that rocket and motor combo.

https://www.rocketryforum.com/showthread.php?t=4357