ejection baffles

[Chad]

I have used both pistons and baffles in low-mid power rockets. Baffles are a partial solution, but do what they are intended to do- trap hot particles and cool the gases. I still use kevlar blanket or wadding with a baffle, but I see much less scorching and need less cleaning with a baffle.

I have a Swift upscale where the ejection charge is 1″ from the chute, but I have a skinny baffle in between with copper mesh inside. With only minimal wadding (there isn’t room for a nomex blanket) the chute is OK. Copper or brass mesh is essential for cooling the gasses. Don’t use steel wool as it will catch fire.

I find the sinuous baffles less effective and am afraid they would blow apart with too strong of an ejection charge.

I’ve used mesh filled baffles up to 2.5″ airframes, but think I would steer away from a baffle on larger diameters as the volume of air moving through is higher and the pressure lower with larger airframes.

Pistons are a more elegant solution, but I’ve been nervous about using them in paper tubes commonly found in low and mid power. I haven’t had any of my two piston rockets get a stuck piston, but I can easily see it happening. As others have posted, they would seem to be more reliable with smooth sided tubes.

What I like most about baffles is that they can be easily integrated into a coupler used with a mid-ejection design (to prevent zippering). Here is an example:
http://www.vatsaas.org/rtv/construction/antizip/anti-zipper.aspx

[Bruce R. Schaefer]

Don’t use steel wool as it will catch fire.

Steel wool, with the proper oxidizer, can be used as a fuel in amateur rocketry—not to be confused with what we do. Good thing you pointed this out, Chad. You probably saved someone some grief.

[greywolves]

Thanks for all the replies. New rocket is almost done. Very happy with build so far, still needs color. Excited to see new design this weekend.

3,2,1, Launch!!!!!!!!!!!!!!!!

David

[Author]

Posts