Launch report 7,5 liter rocket Team.[D&P] Rockets*

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Daan.[D&P]Rockets*
Current WRA2 Flight Duration World Record Holder
Current WRA2 Flight Duration World Record Holder
Posts: 138
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Launch report 7,5 liter rocket Team.[D&P] Rockets*

Post by Daan.[D&P]Rockets* »

Hi,

Here is our latest flight with our 7,5 liter rocket:

[youtube][/youtube]

But in some kind of way the altimeter beeped out 1252 feet. Instead of around 620 feet.. :?
I heard from aircommand that it could be due to a vacuum created on inside the rockets body. Causes to get a failure altitude. The altimeter we used is an alt 15 K from perfect flight.

But its kind of strange because we never had such weird altitude measurement mistake..

Sadly we could not launch a second time that day to see if it was a once in a lifetime mistake ;)

Gr Team.[D&P]Rockets*
SaskAlex
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Re: Launch report 7,5 liter rocket Team.[D&P] Rockets*

Post by SaskAlex »

I take it 620 is the expected altitude from some simulator work? Do you guys have the PC data connection kit so you can look at the flight curve?
air.command
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Re: Launch report 7,5 liter rocket Team.[D&P] Rockets*

Post by air.command »

Hi Daan,

A few more things that could potentially give erroneous readings with the altimeter, some are more likely, while others less likely:

1) I've heard that temperature changes or direct sunlight on the sensor could cause it to give false readings though I am not sure by how much.
2) Perhaps somehow the altimeter was mis-calibrated prior to launch.
3) If the port hole for the altimeter is located in such a way that it is near a low pressure area of the rocket such as just below the nosecone.
4) As I said before this is quite a common source of false readings: Parachute ejection event creating a temporary vaccum.
5) Landing event - potential bottle/payload bay compression and spring back can cause a brief lowering of pressure inside the bay.
6) Low battery?
7) Payload bay components moving in the payload bay during launch. You mentioned this was a higher pressure launch, and perhaps the altimeter mount settled more.

Without seeing a full plot of the altimeter readings it is hard to determine at what point that reading was obtained. Are you able to download the altitude plot from the altimeter? Flying it again should hopefully help resolve that issue.

- George
http://www.AirCommandRockets.com
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Daan.[D&P]Rockets*
Current WRA2 Flight Duration World Record Holder
Current WRA2 Flight Duration World Record Holder
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Joined: Fri Jan 11, 2008 4:19 pm

Re: Launch report 7,5 liter rocket Team.[D&P] Rockets*

Post by Daan.[D&P]Rockets* »

Thanks,

I havn't been able yet to download the plot. Because my brother got my cable ant took it to his home.. :roll:
When I've downloaded the data I will post it here and we can discuss further.

Gr Daan