Port Holes

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Well-Known Member
Jan 17, 2009
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When you drill your port holes do you chamfer the hole or do you just leave the hole square. I like to chamfer mine but was wondering if this may cause any problems with air flow.
I've always left mine flat, without a chamfer, at least on the outside surface. Usually I put some CA in and re-drill and then sand the inside flat with the tube.

The way I do mine, chamfering would be an extra step and I just don't bother. I don't know if it would mess with air flow, it might. Maybe a little venturi affect.
i leave them square, have not thought about air flow issues, i'm too lazy to chamfer them.
I leave my port holes square..Same with my starboard holes..:roll:
I try to make the holes "square" and clean the edges as much as possible. CA does seem to help get those edges nice and smooth. And remember to read the recommendations in your altimeter's technical manual...
Mine are square.

In cardboard tubes, the holes are soaked in CA and drilled again then sanded.
I guess I should explain little more about the type of tubes I am using. All of my DD rockets are glass covered cardboard tubes or they are composite tubes. Also when I am saying about chamfering them it is a very small amout just enough to clean the edge of the hole.

As far as effecting the alt performance I have not seen any ill affects. All of mine have deployed at apogee. It was just something that I was wondering about.
I don't think it would matter. Chamfered or not, as far as portholes go .... size matters.

Did you get my email?
On cardboard I drill the holes then I wick in CA followed by re drilling then sanding. On Phenolic I just drill the holes and sand smooth same with composite covered tubes. I have used a countersink or center drill to clean up the edges.