Each flight log entry usually represents a launch or test day, and describes the events that took place.
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Date:  16th May - 1st August 2010
Location: Denzil Joyce Oval, NSW, Australia
Conditions:  Cool, clear skies, wind  >10km/h at times.
Team Members at Events: PK, GK, PaulK, JohnK, MC, RC

The following update is a compilation of 4 different launch events spread over 2.5 months as we developed and test flew the Mk 3. staging mechanism.

Mk 3. Staging Mechanism

A question we are often asked is how to build a simple staging mechanism. The one we normally use on our bigger rockets, is complicated to build, relatively expensive, fairly heavy and is not really suitable for smaller rockets. We normally recommend the crushing sleeve mechanism that has been used for many years, as it is simple and effective. The Mk2 stager was an all mechanical solution, and though it worked (sometimes) it wasn't really practical as it used many custom parts and took a long time to make.

So with the Mk3 stager we decided to take the approach where anyone should be able to build it out of common inexpensive materials without needing special tools. It also had to be suitable for smaller rockets. The other main criteria was that the sustainer should use the standard 9mm Gardena nozzle to allow it to be used with our regular rockets. The Mk3 design is partly based on Richard Wayman's RIG stager that fixed the Gardena collar permanently and allowed the inner mechanism to move. (here are the RIG Stager details) The mechanism activation though is based on a different principle and is independent of pressure as we did in the Mk1. Stager.

How It Works

A full explanation with detailed diagrams is here: Mk3 Stager How It Works.

Construction Tutorial

A full tutorial on how to build the stager is here: Mk3. Construction Tutorial

Testing

For the first 3 sets of trial flights we used a Baryon I booster made out of a single 2.1L spliced pair. The sustainer was made from a single 1.25L bottle without any fins or recovery system. Since we were really only concerned with whether the staging mechanism worked or not, we did not care about the sustainer flight profile. A simple bottle is also a lot easier to replace if the staging mechanism fails.

1st Trials - 16th May 2010 - 7:00am - Denzil Joyce Oval

On this day we flight tested the Mk3. stager for the first time. The stager used the weight of the sustainer alone to keep it locked in place.

The one successful flight was encouraging in showing that the stager can work, but it looked like there wasn't enough force to separate the stages. Since we damaged the only stager we had, we had to stop after the 4th flight.

2nd Trials - 13th June 2010 - 7:30am - Denzil Joyce Oval

Because the sustainer failed to release mid air, we added a stronger spring for the next set of test flights. With the stronger spring there was a higher chance of the light sustainer being released on the pad, so a locking tab was added and tied to the launcher. This is released on launch and the acceleration keeps the sustainer in place.

This was only a minor issue, but we had to abandon the launch attempt as we did not have a way to fix it in the field.

So we replaced the bead with a pen tip and secured it in place with a couple of loops of wire.

3rd Trials - 4th July 2010 - 7:30am - Denzil Joyce Oval

For these launch trials we also secured the non-return valve inside the Gardena coupling with a wire loop to stop it potentially slipping out of the tube. We also replaced the bead with a pen tip and secured it again with wire. These launches also used the locking tab attached to the launcher, as well as the stronger spring.

Water fill on these flights was 700mL for both sustainer and booster. The last flight used 800mL in the booster. Both booster and sustainer used a 9mm nozzle.

These flights were quite successful in releasing the sustainer at about the correct time, when the booster stopped producing thrust. We again used just a simple bottle as the sustainer without fins. It was very evident at how unstable the sustainer was after release.

4th Trials - 1st August 2010 - 7:00-8:30am - Denzil Joyce Oval

This set of tests involved using a larger booster (Baryon IV) and sustainer (Tachyon VIII) to test the stager at higher loads. Originally we were going to take these to Doonside, but because of the launch cancellation we performed the tests at our local park at lower pressures.

The booster has a 3.1L capacity and uses a 9mm nozzle. The sustainer has a 2L capacity and also uses a 9mm nozzle. The better combination would be a 15mm nozzle on the booster and a 7 or 5mm nozzle on the sustainer.

The parachute on the boosters was deployed using the piano hinge method we use on our drop-away boosters. It is a simple and reliable method of deploying the parachute after staging.

On all three flights the stager performed well though one was slightly damaged when it came down stager first and hit the ground. The other was damaged when one of the crew accidentally dropped the booster onto the stager after picking it up off the ground. Both repairs are minor and easily fixed.

Dad also had to make a new adjustable ring brace for the medium launcher as the ones we normally use are too small to fit the larger fins on these boosters.

The sustainer got stuck in a tree on the last flight. It wasn't too far up so we tried using a line with a heavy weight on the end to hook over the branches. After about an hour of trying, we gave up, and came back later in the day with stronger rope to help get the branches bent over far enough. We were happy to get the rocket back in one piece.

Here is a highlights video of some of test flights over the last 2.5 months: