Happy Sunday. I wasn't able to attend my club's launch today, so I am home reviewing some footage from my HPR Level 1 Cert flight. I wanted to get an accurate altitude at apogee. OpenRocket calculated the Hobgoblin -- that weighs 1207g with an H210 onboard -- to reach ~ 797 meters (2,614 ft). The Estes altimeter read back 4,312 ft. From experience, I suspect that the OR value is a bit high and that the Estes value is "SnoopDog" high (I am in Colorado).
However, I do have my onboard footage from the flight and was able to pick out some ground points. From the photos below, I found two points on the ground that are ~ 2,046 feet apart using Google Earth. taking the snapshot from the video, I was able to measure this distance on my monitor at 10 inches. I calculated:
h / d_actual = d_apparent / 1 unit
h / 2047 feet = (10in) or 0.833 feet or
h = 0.8333 ft * 2047 ft; thus
h = 1,705.83~ ft.
***
EDIT:
Camera Used: RunCam2 4k
FieldOfView: 120 degrees
FocalLength: 40mm
***
It has been a long time since doing something like this and I was wondering if anyone can check my method to see if this is the right way to do this and if I am missing something. 1,700' does line up closer with the OpenRocket Sim. Typically, OR is within 20% of the actual result but it was 35% high on this sim. I was pretty detailed in my calculations but there could be various anomalies not accounted for. Also, ChatGPT seems to agree with me but I wanted to check in for some validation of my method to see if this is a viable alternative to calculating altitude.
Thanks for your help.
However, I do have my onboard footage from the flight and was able to pick out some ground points. From the photos below, I found two points on the ground that are ~ 2,046 feet apart using Google Earth. taking the snapshot from the video, I was able to measure this distance on my monitor at 10 inches. I calculated:
h / d_actual = d_apparent / 1 unit
h / 2047 feet = (10in) or 0.833 feet or
h = 0.8333 ft * 2047 ft; thus
h = 1,705.83~ ft.
***
EDIT:
Camera Used: RunCam2 4k
FieldOfView: 120 degrees
FocalLength: 40mm
***
It has been a long time since doing something like this and I was wondering if anyone can check my method to see if this is the right way to do this and if I am missing something. 1,700' does line up closer with the OpenRocket Sim. Typically, OR is within 20% of the actual result but it was 35% high on this sim. I was pretty detailed in my calculations but there could be various anomalies not accounted for. Also, ChatGPT seems to agree with me but I wanted to check in for some validation of my method to see if this is a viable alternative to calculating altitude.
Thanks for your help.
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