Archive for October, 2008

 

Main Parachute Module + Large PPNC Dummy Module

Main Parachute Module
After the last crash, we decided to split the main parachute module and the PPNC Nosecone.

We used the same design as the drogue parachute module for the main module by shrinking the bottom section of a 1.25L bottle and cutting the top off. The existing nosecone structure and door panel were used. The tomy timer was stuck on top of 3 layers of corrugated plastic to enable the handle section to protrude past the wall of the rocket.

Main Parachute Module

Main Parachute Module

This module weighed in at 54 grams minus the parachute. Click here for other module weights.

Full Size Dummy Nosecone
The dummy nose cone was built from a new bottle. This one is a full height dummy nosecone. A small section was cu tout of the bottom so as not to interfere with the door of the main parachute module. We also decided to fly it without the bubblewrap to see how it would fair in a crash.

Full Size Dummy Nosecone

Full Size Dummy Nosecone

This module weighed in at 23 grams . Click here for other module weights.

Posted by on October 19th, 2008 2 Comments

Launch Abort Test

This weekend we did a few tests of the launch abort system. We used 1 bottle with 700ml of water and pressurized to 100psi. The valve holds the pressure well, we stand on the “T” section just in case the pressure release causes it to fly back up and hit you in the face.

We took a video below. Watch the water level go down in the bottle :)

Posted by on October 18th, 2008 Comments Off

Launch Abort Modification

This is a modification to the launcher to allow us to abort a launch. If we have an emergency or a leak while the wrocket is pressurized we can safely relieve the pressure without a launch.

We decided to put the valve between the pump and the quick release so that we could use it when doing hydrostatic tests.

The valve is sturdy hard plastic ball valve, it has a 15mm thread which we connect to a 13mm tail, a piece of 13mm pipe then to a 13mm T piece into the main line from the pump. The threaded connection into the valve is Teflon taped and tightened, the other 13mm joins all have screw down metal clamps.

It was tested at 110psi tonight and worked as expected. Here is a couple of pics of the valve

Launch Abort Valve

Launch Abort Valve

Launch Abort Valve + Quick Release

Launch Abort Valve + Quick Release

Posted by on October 14th, 2008 Comments Off

Launch Day 9

Launch Day: 9
Date: 11/10/08 Late Afternoon
Location: Montview Oval
Rockets: H2

The intention of today’s launch day was to test the dual parachute deploy.  We had to wait until late in the day to get access to any of the local ovals as the local cricket matches are starting later due to daylight savings …

Here is a pic of H2 ready to fly with dual parachutes

H2 with dual parachutes

H2 with dual parachutes

In fading light we setup and everything was ready to go. Unfortunately we had a pressure leak at 80psi. As we don’t have a launch abort on our launcher yet we had no choice but to launch. As expected the wrocket lawn darted and damaged the PPNC with the main parachute. Here is a pic just before crash down of the drogue deployed trailing behind the wrocket about 0.7s before crash down

crash with late drogue deploy

crash with late drogue deploy

The PPNC was too damaged to fly again although the drogue module looked fine. We also took along one of the dummy nosecones so this was fitted with just the drogue chute and readied to fly again.  The nozzle was tightened and pressurized to 100psi for a launch. This launch was much higher but still no deploy … (scratch head). We looked at the damage and the elastic band was broken but the door still closed. On closer inspection, when fitting the dummy nosecone we had inadvertently taped the door closed :(

We checked the video later and had a flight time of 9.6 seconds, which is pretty good, around 250 – 300 ft

This crash had loosened the tomy timer from the support structure but it was still held in place by the wire although not very well. The rest of the drogue module was fine, just straightened out the dummy nosecone and decided to try again.

Pressurized to 100psi, good flight, again no deploy. The timer due to being loose didn’t detach from the flap. Lawn Dart again. By this time it was almost dark so we called it a day.

Things we learned

  • A simple error of not pressure testing the pressure bottles with its nozzle fitted properly cost us. We will need to pressure test before a flight day in future.
  • The modular approach works well, just be careful taping modules together in the field.
  • We need a launch abort system on the launcher …
  • Crashing the PPNC with parachute lets us develop a main chute module minus the PPNC. Hopefully this will make these modules last more than 1 crash

Posted by on October 14th, 2008 Comments Off