parallel staging question

[timothyterpsalot]

I came across this link on the forum: https://www.rocketryforum.com/showthread.php?t=8739&highlight=navaho
I was wondering if anyone had attempted to parallel stage two completely seperate rockets like this before. I have never seen anything like this and I am wondering about the stability with the off center thrust.
I dont imagine it would be hard to get them to stage. I had an idea of having rail guides on the upper stage slide into a rail (such as a sliding closet door wheel guide, etc.) on the booster and bend or epoxy off the rear end of it. The two stages would drag sep. after booster burn out that way.
Have any of you seen anything like this before? Thanks!

 

[redsox15]

that was my original post and I asked the same question to myself that you pose. I hope to be successful in my future build of this rocket but ALOT of planning needs to go into this design to make sure the flight is straight up into the air rather than up for 20 feet then the rest of the flight be horizontal.


Matt

 

[bobkrech]

If you have a copy of Stine's "Handbook of Model Rocketry" you will see that parallel staging of model rockets was done in the 60's.

There is a bit of a difference between a parallel stage rocket and a clustered rocket. In a clustered rocket, all motors are attached to a single airframe. By canting the motor tube to point toward or thru the loaded rocket cg, if a motor does not ignite, the rocket will still ascent vertically. In a parallel staged rocket, if a motor does not ignite, it is unlikely that the rocket will ascend vertically and more importantly, depending upon the attachment method, the parallel staged booster could separate making for a very unstable flight.

George Gassaway has flown a parallel staged Space Shuttle many times. A key to success is to really understand the motor ignition process and to use igniters that are capable of simultaneously igniting all engines. Boris Katan is a master at this, but it requires a religious attention to detail, especially if the motors are APCP and of different sized. BP motors are easy to ignite simultaneously, but APCP motors are not. Large APCP motors generally take a longer time to come up to pressure than smaller APCP motors, to any additional ignition delay is a problem.

Certainly in a high power rocket, the CTI ProXX motors with a built-in ignition pellet are the most consistent in terms of prompt ignition in an off-the-shelf motor. You have to purchase Quickburst igniters or make your own igniters for other brands of motors to get prompt ignition.

With BP motors, you probably should use the Quest Q2 igniters as an off-the-shelf solution because they appear to be more consistent than the Estes igniters in terms of prompt ignition.

There a lot of ways to connect the parallel stages to the main rocket. Most would employ a base attachment that serves as a pivot point, and have a tube attachment at the forward attachment point and use the ejection gas from the booster to kick the forward end of the booster away from the main airframe and let the air stream complete the separation. This is not unlike separation process for the SRMs on the Shuttle.

Bob

 

[timothyterpsalot]

Thanks for the information Bob. But my question was focused specifically on the design in the link. Some of the usual parallel staging information doesn't quite apply in this situation.
This design is the staging of two seperate rockets, one being the booster, and one attached to the side of the booster being the sustainer.
Usually parallel staged rockets have small boosters attached, not an entire rocket.
Any thoughts?

 

[WillMarchant]

Parallel staging implies simultaneous ignition. The Navaho (one of my all time favorites, by the way) used a rocket booster to accelerate the ramjet powered cruise missile.

So, if you were to power the cruise missile portion, you'd probably want to start those after the booster burns out. That way you can have the booster motor line of thrust through the CG of the whole stack.

Instead of rocket powering the cruise missile, it should use electric ducted fans and be radio controlled. :2:

https://www.aeroconsystems.com/Navaho.htm has a lot of great info including a photo of a modroc version of the Navaho.

Tim Wilson published plans www.rocketreviews.com/images_descon/navaho.pdf for a parasite boost glide version that is semi-scale-like for DESCON-X.

 

[redsox15]

I have zero experience flying/building R/C planes/gliders but that would be cool as well. If it is possible I would love to make the cruise missile rocket powered but who knows...

Those links are great...in all my searching I did not find either of those.


Matt