Just gotta Vent...LOL

[Steward]

Where do I need to go to find information on venting...???
I see it occasionally here on the forum but not enough to understand...When and what circumstances would this be needed...??? Does it fall into the high MPR end...???

Really just trying to increase the old learning curve here....

THANKS in advance.....Steward

 

[Micromeister]

Stewart
If I understand your question correctly, Venting is usually associated with Gap staging, or Staging where the motors are seperated by several inches but still want to use the hot and flaming particles from the booster motor to ignite the sustainer or upper stage motor. Venting reliefs the pressure build up inside the motor tubes while directing the hot particles into the nozzle of the engine above. If you can get your hands on a copy (any edition) of G. Harry Stines "the Handbood of model rocketry" there is a section devoted to this practice, the how's and why's.
Hope this helps

 

[PGerringer]

Or, are you talking about venting the airframes so the changing pressure outside the rocket doesn't cause the pressure inside the rocket to cause a pre-mature separation? Or, are you talking about venting an altimeter bay? Or, are you talking about the venting of a hybrid. Seriously, what exactly are you trying to do that requires venting?

Putting physics hat on...

 

[Austin]

Steward,

I am not sure if you are looking for Micro's explaination or if you are talking about vent holes in body tubes.

If it is Vent Holes, their primary purpose is to provide pressure equalization during flight; this is so the pressure inside the tube remains the same as the air outside. As a rocket ascends, the outside air pressure drops...this can pose a problem if the pressure inside the body tube is still at ground level. The higher inside pressure can actually "Push" the nosecone or payload section apart during flight, which is a bad thing.

To help prevent this problem, pressure relief/vent holes are drilled in the body chamber so pressure can equalize during flight. Drilling a 1/8" - 3/16" hole for a 2" - 4" body tube is all it takes...just make sure you drill it a couple inches away from the nosecone base on a basic model or from the coupler if using a payload model.

Hope this helps,

Carl

 

[eugenefl]

I think this answers part of your original question, but I think this would go in the "Techniques" forum. I suppose it could work in the High Power forum too. Aren't you glad you asked?

 

[Steward]

NAW..I'm not about to poke any holes in any of my rockets...not yet...!!! No..I'm just learning(I hope) for a better understanding as I move into a higher power situation...I think that what I was looking for was the instance of higher pressure in the body tubes...but you all have great info for us...

And I guess this should have gone in the MPR or HPR threads...even though I'm not quite there....Thanks again...!!!

 

[Mike]

Out of interest what kind of altitude is it recomended that you start cutting vent holes?

 

[PGerringer]

Personally anything larger than an estes gets an airhole as far as I'm concerned. No matter how high it flies. It could be unnecessary but it also doesn't hurt to have one. The only estes size that I put an airhole in was when I glassed a supershot. I was launching it on Fs...