CG/CP question

[Starfire73]

This is my first totaly scratch built/original design rocket called: DX-1.

I flew it yesterday on a B6-4. It was an excellent flight. However, it (almost imperceptably) wiggled just a little bit the first 10 to 20' off the pad, then flew high and straight as an arrow.

I was wondering what the slight wiggle at the start might indicate (if anything).

We had a SSE wind at about 6 - 8 mph. Launch rod was about 5-10 degrees into the wind.

Check out the pics on my website:

https://webpages.charter.net/starfire73/MiscPhotos.htm

One of them shows where the CG is, and yes, I did a swing test with perfect results before launching.

There are 5 lead BBs in the nose cone. I put those in there to compensate for the forward fins. The rocket weighs 2.3 oz at lift off.

Does the CG look right? Where do you suppose the CP is? Would a slight wiggle at take off indicate under stable, or over stable?

 

[lessgravity]

I've seen the wiggle in a few of my very stable rockets caused by two things. Wind gust during liftoff and launch rod whipping. Your rocket seems stable enough but could one of these items be the possible cause?

 

[Starfire73]

Originally posted by lessgravity
...but could one of these items be the possible cause?

Sure could be. Of course, I've only had one test flight so far, so it's kinda' hard to tell a lot from only one flight. I'll do another launch or two as is, and if it does it again... I'll try either adding nose weight or removing nose weight. I'm just not sure which to try first - adding or removing - if it does do it again.

 

[TeenRocketNerd]

I really can't imagine that a design such as that would require more nose weight. I could be wrong tho, but in any case, awesome design!

 

[Philosophico]

Nice looking bird

Kinda Blackbird looking, cool.

 

[Stymye]

nice design.! the wiggle could be from the fin slightly flexing.