Where to put camera and how to get a shot of the ground at apogee

[Carter12]

Tldr: How would you do, fast rocket goes high makes it harder.

I want to make a L2 rocket that goes up to a high altitude and has a video feed that includes the ground so that I can calculate the altitude about ground and compare it to apogee data from barometer and altimeter. My goal is at least 15000ft with camera feed, barometer, CO2 concentration, tracker(s), and temperature. I am restricted by budget and L2, but if I can get a tube sponsor I can probably hit well over 20000ft

My original idea was a camera that would rotate around the rocket body using gravity, but since the rocket is in free fall at that point gravity would have no effect.

The biggest challenge to this is the rocket could very well approach velocities of close to mach 2, so an external camera is sketchy to me. Ideas that have popped into my head thusfar is a camera hole and hoping I get a good frame of the ground at some point. Maybe not at apogee but I should be able to match the time with altimeter data. The other option is attach a parachute, tracker, and noisy alarm to the camera and release it at apogee and hope to retrieve it.

Do you all have any ideas on how to achieve this? Feel free to ask more questions if you need or want more information.

 

[Handeman]

Depending on the camera, you can make or buy shrouds that will protect the camera during flight.
You can also determine altitude by the image from the camera, but it won't be easy. You will need to know exactly what the field of view and image sizes are for the camera and you will also need to catch an image of something on the ground of a known size and dimension and the angle from vertical that the image was take at.
The spy satellites have been doing this since Corona was dropping film buckets over the Pacific in the 1960s. You should be able to find info online on how to do the calculations and what info you will need to get accurate numbers. The spy satellites where at a known altitude and known camera lens dimensions to calculate sizes on the ground, but altitude is just another variable and if you know the size on the ground, you should be able to calculate altitude.

 

[atestani]

As has been said, calculating altitude from video will be really hard. I would add that the video through apogee will be a bit dizzying due to pitch, yaw, and roll of the rocket as it ascends. Once ejection occurs it will definitely make you dizzy watching it.

If you are interested in video of the ground as the rocket ascends and the ground after the chute deploys, you could simply have two cameras.

I do this on all my flights and it works quite well. I am using SQ11 cameras which are about 1 inch cubes with "shrouds" as in this post:
https://www.rocketryforum.com/threads/video-camera-holder-opinions-please.183594/ The shrouds are conformal to the body tube and are screwed into a fiberglass body tube so they are quite rigid. I would only use these on a cardboard tube if they were screwed into centering rings or bulkheads. I have flown these on many flights including my L1 and L2 cert flights but I have not flown them supersonic yet. I'll being doing that in May.

If anyone is interested in the STL files for either of the shrouds, just PM me. There are other shrouds available for sale and also on 3D printing sites.

 

[teepot]

If you put the camera inside the BT, you might be able to use a mirror to get your ground pictures. I haven't tried it, but I know it's been done.

 

[Maxhiker14]

Have you seen the tiny fpv racing cameras (like the runcam split)? The sensor/lens is separate from the board. I would just securely mount the lens externally pointing down and put a shroud above. I think it's low enough profile that it should be fine. Also, if you're looking for a good rocket to get you up there- the Wildman Mach 2 might be a great option. It's affordable and can easily get over 20k on L2 motors.