Telling hight of a rocket

Discussions about rockets, construction materials, adhesives, nozzles, nosecones and fin design.
User avatar
dwrrule
WRA2 Member
WRA2 Member
Posts: 134
Joined: Tue Apr 22, 2008 12:33 am

Telling hight of a rocket

Post by dwrrule »

Just wondering is there a way of telling how high a rocket is by a video or a picture?
User avatar
Tim Chen
WRA2 Member
WRA2 Member
Posts: 871
Joined: Wed Jan 31, 2007 1:44 am

Re: Telling hight of a rocket

Post by Tim Chen »

dwrrule wrote:Just wondering is there a way of telling how high a rocket is by a video or a picture?
I have seen it done before but from what I have seen it is not very accurate. The general theory is that you take a photo from apogee that has something visible on the ground like a fence or light posts or houses and you print out the photo and measure the distance with a ruler. Then you take the same camera and take a photo of the same object from a known distance away and print that out and measure it. The ratio of the two measurements can then be applied to the known distance and you can get the unknown distance (the altitude).

The method is probably only accurate to 10% or so because of imperfections in the lenses and the cheap cameras we fly. But it's a good ballpark number.
Tim Chen
Captain, Team Enterprise
User avatar
dwrrule
WRA2 Member
WRA2 Member
Posts: 134
Joined: Tue Apr 22, 2008 12:33 am

Post by dwrrule »

Are the Altitude finders from Estes a good way of finding how high you are?
User avatar
Brian
WRA2 Member
WRA2 Member
Posts: 496
Joined: Fri Feb 08, 2008 6:02 am

Re: Telling hight of a rocket

Post by Brian »

Tim Chen wrote:
dwrrule wrote:Just wondering is there a way of telling how high a rocket is by a video or a picture?
I have seen it done before but from what I have seen it is not very accurate. The general theory is that you take a photo from apogee that has something visible on the ground like a fence or light posts or houses and you print out the photo and measure the distance with a ruler. Then you take the same camera and take a photo of the same object from a known distance away and print that out and measure it. The ratio of the two measurements can then be applied to the known distance and you can get the unknown distance (the altitude).

The method is probably only accurate to 10% or so because of imperfections in the lenses and the cheap cameras we fly. But it's a good ballpark number.
could u do the opsit, take a picture of the water rocket at apogee and then measure it?
Ascender Water Rockets
http://ascenderwaterrockets.weebly.com/
https://www.youtube.com/channel/UCS2NHXS-VFxEux70DCINR0w
User avatar
Brian
WRA2 Member
WRA2 Member
Posts: 496
Joined: Fri Feb 08, 2008 6:02 am

Re: Telling hight of a rocket

Post by Brian »

Tim Chen wrote:
dwrrule wrote:Just wondering is there a way of telling how high a rocket is by a video or a picture?
I have seen it done before but from what I have seen it is not very accurate. The general theory is that you take a photo from apogee that has something visible on the ground like a fence or light posts or houses and you print out the photo and measure the distance with a ruler. Then you take the same camera and take a photo of the same object from a known distance away and print that out and measure it. The ratio of the two measurements can then be applied to the known distance and you can get the unknown distance (the altitude).

The method is probably only accurate to 10% or so because of imperfections in the lenses and the cheap cameras we fly. But it's a good ballpark number.
could u do the opsit, take a picture of the water rocket at apogee and then measure it?
Ascender Water Rockets
http://ascenderwaterrockets.weebly.com/
https://www.youtube.com/channel/UCS2NHXS-VFxEux70DCINR0w
User avatar
Tim Chen
WRA2 Member
WRA2 Member
Posts: 871
Joined: Wed Jan 31, 2007 1:44 am

Post by Tim Chen »

dwrrule wrote:Are the Altitude finders from Estes a good way of finding how high you are?
Can you post a link or tell us what their name of these is so I can look it up? If it's some kind of altimeter I'd like to chek it out. If it's just a protractor glued to a stick then it's probably as accurate as any other toy.
Tim Chen
Captain, Team Enterprise
User avatar
Tim Chen
WRA2 Member
WRA2 Member
Posts: 871
Joined: Wed Jan 31, 2007 1:44 am

Re: Telling hight of a rocket

Post by Tim Chen »

Brian wrote:
Tim Chen wrote:
dwrrule wrote:Just wondering is there a way of telling how high a rocket is by a video or a picture?
I have seen it done before but from what I have seen it is not very accurate. The general theory is that you take a photo from apogee that has something visible on the ground like a fence or light posts or houses and you print out the photo and measure the distance with a ruler. Then you take the same camera and take a photo of the same object from a known distance away and print that out and measure it. The ratio of the two measurements can then be applied to the known distance and you can get the unknown distance (the altitude).

The method is probably only accurate to 10% or so because of imperfections in the lenses and the cheap cameras we fly. But it's a good ballpark number.
could u do the opsit, take a picture of the water rocket at apogee and then measure it?
In theory this would work but in practice the results are poor because the rocket at a distance is very small in the photo and measuring it accurate is difficult. A small error in measuing the rocket in the photo would mean a large error in the results. The larger the object you measure in the pix, the smaller the error in altitude is. That's why people measure stuff on the ground that's big, like a road or a fence or the distance between two trees or something huge that fills up the picture as much as possible.
Tim Chen
Captain, Team Enterprise
User avatar
Brian
WRA2 Member
WRA2 Member
Posts: 496
Joined: Fri Feb 08, 2008 6:02 am

Post by Brian »

dwrrule wrote:Are the Altitude finders from Estes a good way of finding how high you are?
Estes AltiTrak at http://www.estesrockets.com but you can print one out at http://www.grc.nasa.gov/WWW/K-12/TRC/Ro ... cking.html
Ascender Water Rockets
http://ascenderwaterrockets.weebly.com/
https://www.youtube.com/channel/UCS2NHXS-VFxEux70DCINR0w
User avatar
Tim Chen
WRA2 Member
WRA2 Member
Posts: 871
Joined: Wed Jan 31, 2007 1:44 am

Post by Tim Chen »

Brian wrote:
dwrrule wrote:Are the Altitude finders from Estes a good way of finding how high you are?
Estes AltiTrak at http://www.estesrockets.com but you can print one out at http://www.grc.nasa.gov/WWW/K-12/TRC/Ro ... cking.html
Those work okay if you're just looking for a ballpark figure as well. The drawback with them is that you need a person to operate it who can't do anything else because it requires their full attention. I only can count on Mark to be available for launches and between the two of us we have our hands full with the launch and can't be taking measurements at the same time.
Tim Chen
Captain, Team Enterprise