Launch Day 7

Launch Day: 7
Date: 20/09/08 Afternoon
Location: Berry Oval
Rockets: H2

Hottest Day of the year today 33 degrees C, so blue sky’s were not a problem, but as the afternoon grew longer the wind started to pickup. We were fairly keen to get a launch in today to test the parachute deployment. We tried a few of the bigger parks, but cricket and baseball are into full swing and the big parks were in use.

We ended up at Berry oval which is always empty in the afternoon, but its a little small. We have flown H2 here before and its always landed in the park so we decided to go for a launch.

We setup as usual, put H2 on the launch pad, setup the timer for 1 wind and waited for the wind to die down a little. We pressurized to 100psi waited another 2 minutes or so until the tops of the trees were still then launched. Here is the video

As you can see, the side deploy nosecone worked really well. Although its not really visible in the video I can clearly remember seeing the rolled up parachute falling alongside the rocket briefly before it opened and the main section of the rocket fell underneath the parachute.

Our jubilation was quickly overshadowed as it started to become obvious the  wind up high was really blowing harder than on the ground or the tops of the trees. The parachute and wrocket drifted out of the park, over the road and into thick bushland.

The search was on … from previous golfing experience I knew to improve the chances of finding it we would have to pick a landmark on the line where we last lost sight of it, which in this case was a tree sticking up higher than the rest .. and we aimed for that, although how far in it landed we weren’t sure.

We scaled a wire fence and headed in through thick bush, always looking up to see if we could see H2 stuck in the tree tops , stamping our feet to scare way any snakes and using sticks to brush spider webs out of the way. (When you have 16 of the worlds top 20 most poisonous snakes and the worlds most deadly spider this is good practice).  It was hard at this stage to even spot the large tree were were aiming for, after a few minutes the trees opened up, the ground was more open and we scaled a hill where the tree we were aiming for was. We looked around from this vantage point and couldnt see the bright yellow chute.

We went past the big tree and the ground sloped down to a fence, again through thick bush to the expressway that we could hear below. It was at this stage that I though we would be building a new wrocket when Mark called out he could see it.

It was hanging in trees about 4m up. There were lots of thin dead trees so getting a long pole wasnt a problem, so after a bit of shaking H2 was back with us … with no apparent damage. The search for the wrocket had been more of an adventure than launching it :)

Here is a picture we took from Google Earth showing where it was launched and where we recovered it (click pic for a larger view).

H2 Flight Path

H2 Flight Path

As you can see Goggle Earth estimated the landing spot at 195m from the launch site, about half of that through thick bush. You can also see how close to going on the expressway it was. Here is a pic from Google Streetview of where it landed, there is a 2m fence between where we were and the edge of the cliff (not visible in the pic) so we were not in any danger of going over the cliff. H2 landed a few meters back from the fence, the treeline you can see is pretty much the fence line.

H2 landing location

H2 landing location

We put the numbers into Cliffords water rocket simulator and came up with ~ 80m (260 feet), which wouldn’t be too far off the money.  Here is a pic after recovery, you can see how thick the bush was here.

Mark with H2 after recovery

Mark with H2 after recovery

Things we learned

  • Make sure you have a big area to launch in when there is wind around. In this instance I think we may have outgrown Berry Oval
  • Looking at the treetops is not always a good indication of how fast the wind is blowing further up
  • We may need to look at a 2 chute deployment system with a smaller drogue chute deploying then the main chute later or possibly just deploying the main chute further past apogee
  • The parachute deploy and PPNC seems to work well, we will continue to test before we fly a camera and an altimeter but we are heading in the right direction
  • The robinson coupling worked perfectly, no leaks and the wrocket sat on the launch pad at full pressure for at least 2minutes without loosing any noticable pressure
  • The wrocket flew very straight, again I was able to see it backside from apogee for the first few metres before the chute deployed

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