Were to Mount an on board camera

[Humma]

I have seen lots of posts of these little key chain cameras that are for video.My question how do you determine were to mount these as not to adjust the CG \Cp ratio.

 

[Fishhead]

I mounted mine close to the top. There was some definite lean during boost, so I might move it down an inch at a time until I find a more neutral spot.
And I'll post pics and videos of the eventual wreckage. ;-)

 

[billspad]

Here are two mounted in the back. It's flown many times with and without cameras and I made no changes to the CG with this arrangement.

Why two cameras? I'm trying to do 3D. I've flown it once and it wasn't a total failure so I'll keep trying until I get something that looks good.

 

[JDcluster]

On bigger rockets: I don't think it makes much of a difference.
I've flown them on my 7.67" Bruiser and one on an old 3.12"scratch rocket.

Here's a pic of my Bruiser with the cam on board.
The camera is under the green tape.



JD

 

[luke strawwalker]

I have seen lots of posts of these little key chain cameras that are for video.My question how do you determine were to mount these as not to adjust the CG \Cp ratio.

The further forward you put it, the more stable your rocket will become (not necessarily a bad thing unless your rocket is borderline OVERSTABLE and your flying in winds which would tend to make it weathercock excessively into the wind.

Simple answer is, if you don't want ANY change in the CP/CG relationship is, MOUNT IT AT THE CG! Balance the rocket in a loop of string tied around the body tube til it hangs level (or on the edge of a ruler or something so it's like a teeter-totter) and wherever it's balanced level is where the CG is. Mount the camera there and you're set-- the CP/CG relationship should be virtually unchanged (there are some SLIGHT aero-effects due to the presence of the thing in the airstream but they're negligible and VERY difficult to model in the computer anyway-- at least accurately).

Adding weight to the back end of the rocket tends to be destabilizing, but if your rocket is big enough and has a good couple calibers of stability or so anyway, it'd probably be ok-- should still either Rocksim it or swing test it to make absolutely sure that the thing is still stable with the extra weight in the back before flying it... Shifting the CG aft by adding weight to the rear end can move the CG behind the CP and make the rocket unstable. That's why adding weight to the front is usually the preferred approach.

Later! OL JR