Introduction

This is the continuation build log of our previous rocket project called "The Shadow". The log is in chronological order so to see the most recent post you need to Jump To The Bottom. You may need to refresh this page to see any latest updates.

CAUTION: If you are going to attempt to build rockets such as these, please exercise extreme care when testing and flying them. This rocket uses high pressures that can potentially cause severe injury to yourself and those around you. Always double check your equipment and review safety procedures before every test and flight. See more information on Safety Guidelines.

Build Log

14 February 2012 - Spent some time looking for the cause of the deployment mechanism failure. See the "what went wrong?" section in the Day 115 flight report for more details. At this stage we will most likely try an alternative way of ejecting the parachute, though we haven't made any decisions yet.

Deployment mechanism as it came out of the ground.

Testing the servo timer and servo.

16 February 2012 - We mixed up some detergent and water and poured it into the aft end of the rocket and swirled it around so that all the walls were coated and lubricated. We then pushed the nozzle back into place with a 2m long wooden pole. The integrity of the seal will need to be re-checked in a pressure test.

Before ...

Nozzle pushed back into place

14 April 2012 - After a bit of a break from rockets, we started repairing the Shadow again. We recovered what components we could from the debris. There were actually quite a few we could re-use. We straightened out the lever arm as well as the deployment mechanism end brackets. Really only the balsa wood components and the piston needed to be replaced. All the fasteners, springs etc were still usable. We already had spare balsa wood sandwiches made from before so it was an easy task to just cut out the required components.

16 April 2012 - A busy day. We trimmed the end of the damaged body tube and cut it square. Only about 12cm of the end of the body tube was damaged. We then took one of the couplers we made earlier that was a little tight and sanded it until it fit in the body tube.

The we took a piece of the 60mm PVC and machined a new retainer ring with grooves for the glue. Having made one earlier and having the tech drawings to go with it made it so much easier. We cleaned the end plug as it had dirt on it from the impact. Thankfully this was intact without any damage. This is a critical component and is made to tight tolerances.

We made another piston guide for the ejection mechanism. These are just made from old aluminium knitting needles. They telescope well into the aluminium tubing we use for the piston. We epoxy a small machine screw into the end of it so we can mount it easily.

In the afternoon we made a new nosecone using 6 x 200gsm and 6 x 85gsm cloth gores. We spaced them out more evenly this time which gave a more uniform wall thickness.

We also machined a new deployment mechanism support ring from PVC that the entire deployment assembly rests on.

End of the damaged body tube has been trimmed.

New coupler, and retaining rings.

Fiberglass gores ready to make up a new nosecone

Nosecone plug mounted in the chuck of a cordless drill to make it easy to turn by hand as the glass is applied.

All layed up and waiting for the epoxy to cure.

17 April 2012 - We took the nosecone off the plug today. It came off very easily due to the three layers of balloons with silicone grease between them, but the outer most balloon did not want to come away from the fiberglass very easily at all. The rubber looked like it bonded well with the epoxy. I'm not sure why that is, but the problem did not occur last time. We removed most of it except in the top third where it really doesn't matter.

We then sanded the whole nosecone with coarse sandpaper. I always find it easier sanding it under a running tap as you don't get the dust and it washes the dust from the sandpaper.

We attached the straightened-out end brackets to a new piece of balsa sandwich.

Straightened brackets mounted to the a new balsa sandwich.

Nosecone removed from the plug. The blue is some balloon left stuck inside.

18 April 2012 - Today we glued in the nosecone tip which we recovered undamaged from the previous nosecone. We also epoxied the locking ring on ejection piston tube. The lever arm locks against this ring. We glued the bulkhead into the nosecone coupler.

Nosecone coupler.

19 April 2012 - We made the bulkheads for deployment mechanism today. They were just cut from the balsa sandwich.

New bulkheads attached to the mechanism

The ejection piston still needs to be cut to length.

21 April 2012 - Made a new fiberglass body tube approximately 700mm long. Part of this tube will be the payload section and the other will be the pressure chamber body. Although the payload bay tube may be a little heavier than needed because it is not pressurised, it was just easier to make both of them at the same time. After we rolled the tube and had it on the rotisserie for a while, we dry brushed the surface to remove little bubbles that sometimes form from the roller. This makes for a much smoother tube and less sanding.

The nosecone was sprayed with filler putty and the nosecone bulkhead was made and glued into the nosecone coupler.

Laying up a new body tube.

Baking on the rotisserie.

Spray painting the nosecone with putty.

22 April 2012 - The servo motor and STII were attached the deployment mechanism. We machined a new ejector plate adaptor for the piston as this was also damaged in the crash.

Servo and STII mounted.

Piston cut to length with Ejector plate adaptor.

New tube removed from mandrel.

24 April 2012 - Today we sanded and trimming the body tube and cut it to length. We also decided to use one of the existing couplers that we made earlier but was a little over size. We just sanded it back down until it fit snugly. The coupler was glued into the pressure chamber.

11th June 2012 - Today we glued the body tube extension onto the pressure chamber. We also looked at how easily the nosecone coupler could slide out of the payload bay tube and it was sticking a little, The fiberglass on fiberglass friction is fairly high and if you angled the nose a little it would wedge, So this time we are going to make the coupler from the PVC pipe that we use for the mandrel. Because the PVC is thicker than it needs to be we machined out the center of it to make it lighter. This way we also made a small shoulder for the bulkhead to rest against. It seems like it slides better in the payload bay tube.

18th June 2012 - The end plug was glued in with the retaining ring today. We always use a little soapy water to get the o-ring to slide into the tube rather than silicone grease because we don't want any of the grease on the bonding surface. We then thoroughly dry and sand the bonding surface before applying the epoxy. We also made and attached the nosecone bulkhead into the nosecone coupler. And lastly we glued the CF tube into the payload bay tube that will be the main attachment point for the parachute.

Pressure chamber extension and end plug glued in place.

CF tube attached to payload bay.

New PVC coupler and glued bulkhead.

19th June 2012 - Today we attached the ejection mechanism to payload bay with 6 screws. The screws attach the payload bay through the PVC ring at the base of the mechanism.

Drilling holes for payload bay.

The rocket just fits onto the bench

20th June 2012 - We cut slot in nosecone coupler to make room for the CF tube and glue. The nosecone was also painted. The payload bay was also attached to the pressure chamber by drilling and tapping 8 holes in the retainer ring.

Tapping 8 holes for the screws

Nosecone with glued in coupler.

Ready for painting

Final coat of paint.

23rd June 2012 - Today we  started working on the payload bay framework. This framework sits right up against the pressure chamber and below the parachute ejection mechanism.

We also did the first parachute ejection tests with the new mechanism. The first two test went fine with plenty of power ejecting the parachutes, but on the third attempt the nosecone was wedged at an angle and did not deploy. This would have been resulted in a crash. I carefully removed the nosecone to see why and it was caused by the parachute being packed long and thin. The bottom of the parachute was on one side, while the top of the parachute was pushing against the other side of the nosecone. This may be in fact what happened during the crash.

So I repacked the parachute to be short squat and round to more evenly distribute the load and the next few tests were fine. We will test it quite a few more times before the launch to make sure that this different packing technique is fine.

24th June 2012 - Today we did a hydro pressure test of the rocket's pressure chamber. We were happy that it held 400psi (27.5 bar) This will be the target launch pressure for the next launch. The test also showed that the lower part of original pressure chamber was undamaged during the crash. The nozzle bulkhead that had moved half way down during the crash was also okay and the o-ring seal was undamaged.

We also finished making most of the payload bay framework that holds the batteries, camera, and altimeter.

Hydro pressure test to 400psi.

Payload framework. The camera buttons are painted white for easier viewing inside the rocket body.

26th June 2012 - Drilled out the holes to access all the components inside the rocket, The payload bay tube now looks like Swiss cheese. We also ran a number of simulations to figure out how much of a delay to set on the timer.

Rocket assembled.

27th June 2012 - Painted the undercoat on the payload bay as well as the pressure chamber extension.

28th June 2012 - We painted the rocket in the afternoon and had to sit it in front of the heater for most of the night so that it would dry by the next day. This paint normally takes about 4 or 5 days to dry completely.

29th June 2012 - Final preparation and testing of the ejection mechanism. It was discovered that the nosecone to got wedged again. We added about 1cm of padding in the nosecone to allow the piston to have a shorter travel and sanding the PVC coupler allowed the system to eject the parachute cleaner. the #16 HD camera had also packed it in, so we had to replace it with the #11 as that was the only one we had spare.

 

Final payload bay components.

Final ejection mechanism

30th June 2012 - Launch day. We had a great day launching the rocket today. Here is the full flight report from the day. The rocket flew twice, once at 400psi and again at 420psi. It flew to an altitude of 1173 feet on the first flight and to 1239 feet on the second flight.

 

First flight

Stills taken from video of launch

Second flight

Landing.

5th January 2013 - Today we replaced the two LiPo batteries in the payload section. A couple of months ago I had accidentally left the power on to the altimeter which completely drained them to 0V. They also puffed up a bit so we replaced them with a fresh pair.

Puffed up LiPo batteries

Replaced with new pair

6th January 2013 - We made a couple of launcher improvements today. The first was to add a lever extension to the release arm. After a couple of difficult launches to get off the pad, with this extension we are hoping things will be easier. We have also made a new base plate that the whole launcher attaches to so that it makes it easier to swap on launch day with our regular release mechanism. The new plate just slides into place and is bolted down.

Because the base plate is adjustable allowing us to change the rocket diameter we need to set it in the right position for the Shadow. Rather than loading the whole rocket on and off each time, we made a small template that has a rail button and a hole the size of the nozzle so that we can check for clearances and alignment. We had to use a couple of shims under the release mechanism in order to point the launch tube exactly on center.

Extension arm on the release lever.

Release heads are now easy to swap

Release head slides in and is secured with a pair of screws.

Small rocket stand-in template to get the correct spacing for the release head.

9th January 2013 - I reattached the video camera to the payload section. We also shortened about 16 screws that attach the payload bay and ejection mechanism, (because I misplaced the box with the originals). A Dremmel tool with a cut-off disk works a treat to get through them cleanly and quickly. :)

Re-attached camera. The whitened buttons makes them more visible inside the rocket.

Shortened screws

26th January 2013 - Launch day. Shadow II flies to 1248 feet (380m). See the full flight report from day 129 for more details.

Prepping the rocket

Set up and ready to go

Fast launch

420psi

10th February 2013 - Shadow II CATOs. For full flight report including failure analysis please see Day130 Flight Report.

Filling with 1.7L of water

Almost ready to go

Pressurised to 440psi - BOOM

Fiberglass confetti

21st April 2013 - We trimmed the lower and upper sections of the rocket and removed the two couplers. we also had to remove a lot of dirt from inside the rocket from where it landed.

23rd April 2013 - We bought a new roll of 84 gsm glass cloth so we could repair the rocket body. 15m x 550mm wide cost $53

30th April 2013 - Today we rolled the new tube to replace the broken section. We used 6 pumps of the epoxy again which was just right. Back on the rotisserie it went to cure.

4th May 2013 - Rolled a new coupler today from 200gsm cloth. The cloth was 120cm long and about 16cm wide. One pump of the epoxy was enough for the entire roll. We also pulled the pressure chamber off the mandrel and again it came off cleanly.

5th May 2013 - We rolled the second coupler today. We can only roll one coupler at a time because we only have the one small diameter mandrel.

7th May 2013 - Trimmed the couplers and sanded them down to fit snugly into the tubes. We had to do quite a bit of sanding as the couplers turned out a little thicker than expected. This may have been caused by using a brush instead of a roller so the layers didn't compact quite as much.

12th May 2013 - Glued the couplers into the forward bulkhead section and the fin section. These were suspended vertically to allow the glue to flow back under gravity over the internal joint. We again used the super strength 2 part epoxy.

13th May 2013 - Glued the forward bulkhead section to the new tube. We used 3 angle brackets attached with rubber bands to keep the sections aligned. We stood it upright to let the glue flow back over the joint.

14th May 2013 - Glued the top section of the rocket to the fin section. We again attached the angle brackets to keep things aligned and stood it on its end.

15th May 2013 - Spray painted the rocket body with putty. This helps fill in some of the gaps and also gives the paint a good surface to adhere to.

16th May 2013 - Sanded the putty with 400 grit sandpaper and then finished with 1000 grit sandpaper. We then spray painted the rocket with the bright orange paint. We applied about 4 coats and left it to dry.

19th December  tested shadow II standing up to 350psi

Feb 25 - S2 attach camera - S2 attach altimeter with plastic pocket - altimeterone - find S2 screws