Launch Day 8

Launch Day: 8
Date: 23/09/08 Afternoon
Location: Montview Oval
Rockets: H2

Today was another test day. After our last adventure with the parachute deploying and nearly loosing the wrocket, we decided to try a late main parachute deploy to see how it would hold up to opening whilst returning to earth quite fast.

We launched H2 at 100psi and had the timer set for approx 6.4-6.8 seconds (2 winds). There was a bit of wind about so we angled the launcher into the wind. The simulators told us a flight time of about 8.8 seconds which is what he had verified on other flights. In hindsight the 6.4 seconds was a little too late and H2 crashed down without a deploy. We ran the video through virtualdub our video editing s/w frame by frame and we only ended up with a flight time of 7.1 seconds.  This didnt leave enough time to deploy the chute. The smaller flight time than anticipated was probably due to the wind.

Here is the video .. roll the video tape .. I mean stream the bits !

H2 did sustain a bit of damage and the mounting of the tomy timer came off the nosecone structure which meant we didnt get a chance to test with the chute again. So seeing as the nosecone shell was a write off anyway we put it back on the stand and launched twice more at 110psi, which is our highest launch pressure to date.

I will go ahead and build the dual chute deploy system with a drogue chute and the main chute. This will need a new nosecone design and extension as well as a second tomy timer. I have ordered 5 today that should arrive before the weekend. so it looks like no launches this weekend but a lot of building.

Things we learned

  • Predicting the exact deploy time for a late deployment is quite hard, there is not much margin for error. A better system (I think) will be a dual deploy with a drogue at apogee and a main chute later.

This entry was posted on Tuesday, September 23rd, 2008 at 11:30 pm and is filed under Launch Days. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

 
 

2 Responses to “Launch Day 8”

  1. George Says:

    Sorry to hear about the crash. :( Sounds like the deploy was just a tad too late. Keep in mind that depending on your parachute packing technique, the time from timer release to the time the parachute actually fully opens and slows the rocket down to it’s terminal velocity can take one or two seconds.

  2. todd Says:

    George,
    Yes I got it a little wrong. Im not too worried about the crash that all part of testing and learning. I would have been more annoyed if the chute deployed at apogee again and I had to go looking for it in the bush again.

    The late deploy is quite hard it seems, as the rocket is traveling a lot of distance every tenth of a second by that stage and there is only a small window to get it right ..

    -todd-