High Speed Videos

Launch site

This weekend we went out to Doonside to have a look at the site and help out with a bit of mowing to clear a new area for the launch pads. The new area is needed because huge piles of dirt have been pushed up against the permanent pads. Despite there being virtually no rain all week, the road was still impassible as the ground is still saturated with standing water especially near the entrance.

The aeroclub that used to fly on the other side of Doonside has been relocated to our area as well due to the construction, so some co-ordination will be needed but there is plenty of room for everyone so that shouldn't be a problem. Currently the next launch opportunity is July 4th so we are hoping to fly on the day.

High speed video

After seeing the great high speed videos of water rockets made by Dr. Pitan Singhasaneh using a Casio Exilim EX-F1 camera (http://groups.yahoo.com/group/water-rockets/message/9248) We decided to get a high speed camera as well. Unfortunately the F1 is still too expensive here in Australia and so we decided to get it's baby brother the 9MP Casio Exilim FC-100. Overall it's a nice camera with some really cool features. I was really surprised at how small the whole thing is. Other than the 30 fps 1 second burst it can do - which will be great for launches, it can shoot HD video at 30fps, but also high speed video at 210, 420 and 1000 fps. The trade-off is the frame size decreases as fps goes up. The 1000fps is pretty useless due to the tiny frame size but for very specific tasks it may work. For the high speed shots lots of light is necessary otherwise the video is grainy. Both the 210 and 420 fps frame sizes are usable.

I've posted a video of some of the first tests here:
http://www.youtube.com/watch?v=2gIo6iQcRRs

We want to bring the camera with us for launching the big rocket. We have to decide though whether we want to film the launch in HD or high speed. The high speed is likely to be more interesting though.

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Launches on Hold

We are currently in a holding pattern with launches for two reasons: The weather here in Sydney has not been co-operating in the last few weeks and the regular launch site at Doonside is currently undergoing construction. The heavy machinery has torn up the access road and with the rain it has made it impassable.

Here are some recent pictures of the site:
http://www.nswrocketry.org.au/gallery/2009_Launches/Doonside_2009_05/01_photos_May.html

We need to get in and help with the working bee to try to restore the site so it is suitable for launches and parking again, but due to the bad weather this was postponed again. The forecast for this weekend looks more promising with the rain stopping in the next day or so.

Acceleron V

During earlier testing we found that a couple of the 13mm nozzles leaked slightly when the rocket was unpressurised. We are only talking a few drops of water. The o-ring grooves were fractionally too deep, and with the narrow o-rings this is more of an issue. When the boosters were pressurised the o-rings would seal properly. Dad decided to fix the issue and machined up a whole new set of nozzles.

We also decided against a guide rail for this rocket as there is no convenient place to secure it. We could attach it to the outside of one of the boosters, but it could cause more harm than good due to the potential uneven drag on that side of the rocket. The nozzles are quite long ~40mm and the fill tubes are quite a tight fit, so in the absence of a guide rail, the rocket straying from vertical could potentially wedge one of the nozzles on the fill tube causing all sorts of chaos.

We decided to machine out the top 30mm of the nozzle to be about 15mm in diameter and the nozzle hole itself by another 0.5mm. This allows the nozzle to pivot more without seizing on the fill tube. The 0.5mm increase to the nozzle gives about 8% more cross sectional area so we will get a little more thrust on take-off.

Static Tests

While we have been waiting for the weather to clear, we have done more static tests on the test stand of the membrane variable nozzle as a follow up to the tests done in March. We are in the process of putting all the data together at the moment so we will post all the results once they are in a meaningful form. All up there were 19 static firings made last weekend. (14 done in March)

Launch Abort Valve

After recent discussions on the Yahoo water rocket forum we decided to have a go at building a simple, remotely operated launch abort valve. The idea was to try to make it from commonly available components, and no need for special tools. The full details of the launch abort valve are here:

http://www.AirCommandRockets.com/construction_4.htm#AbortValve


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Testing and progress

I've updated the build thread on the Australian Rocketry forum with some of the latest testing and build progress here:

http://www.ausrocketry.com/forum/viewtopic.php?t=1552&start=30

The booster and sustainer are now mostly complete, still with a bunch of little things left to finish. So far the weather forecast looks good for the weekend so we have our fingers crossed.


I'm not sure how many hours we've put into the rocket so far, but it is more than I had anticipated when we started the build. It is probably approaching around100 hours now. A lot of the time is spent thinking about how to solve particular problems, so hopefully the second time around a build should be much faster.
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3 Years

3 years ago today, dad and I built our first horizontal launcher, hooked it up to a scuba tank and launched our very first coke bottle in the back yard. A few days earlier after seeing a Mythbusters episode trying to disprove the Japanese video of a guy getting launched across the water, we looked up water rockets on the net and discovered a whole world of water rocketeers building all kinds of water rockets. And so the fun started....

Before we started collecting detailed flight data for each flight, we did about 60 launches of basic single bottle rockets. Since we started keeping records there have been a further total of 406 firings -

• 5 of which have been pyro rocket flights
• 3 flour rocket flights
  
• 67 static tests
• 331 water rocket flights ( 23 multi-stage/booster flights )

We are still enjoying the hobby, and have a long list of things we still want to try. A big thank you goes to the great water and pyro rocket communities that have prooved to be a very valuable resource in helping to design, build, test and fly rockets.
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Rings, fins and other things

We had quite a busy weekend working on the rocket. The following has been completed:

• The ring brace is now fiberglassed, sanded and painted
• The wiring connections to the servos and pressure switches are complete
• The parachute deployment mechanisms are complete
• The fins are complete
• The sustainer is finished
• The flight computers have been attached
  

Still left to do:

• Painting
• More pressure testing of various components and bottle assemblies.
• Simulations
• Attaching various things like parachutes and the ring brace to the bottles.
• Mounting a camera and altimeter in the booster
  
• Bunch of little fiddly things
• Full integration testing of the entire system at 20 psi
• Launch abort loop and hook
  

One of the main problems we've had is improving the yield of the splices at the 130psi range. Dad pressure tested the 9 spliced pairs to 130psi for 2 minutes during the week. Out of the 9, five were good. Two had very minor leaks of a few drops and a couple had more significant leaks. Dad had a go at sealing them from the inside with silicone and we are waiting to re-test them on Wednesday. We have about 7 spliced pairs currently that we need to test and get 4 good ones out of those. Otherwise there are still 2 good ones we have in the Polaron rocket should we need them.

There are still minor things to finish during the week, but most of the long lead time things are done.
The new ring brace can be seen in the image below (red with white stripes). The red Velcro strips around the bottles and lower section are only temporary at this stage to hold the rocket together as we work on it. It makes it easy to remove bits as needed and put them back.

In the photo below the rocket is still unpainted, but you can see the flight computer compartment on the right, and one of the parachutes on the left.


The new sustainer is a little shorter (about 6 inches) than the photo posted earlier in the month because we decided to put a Robinson coupling in the lowest bottle to generate foam in flight for a longer and more visible burn.

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Acceleron V stager testing

We've updated our main website with more details and photos of the Acceleron V build. There is short video that shows a couple of the pressure tests of the staging mechanism.

http://www.AirCommandRockets.com/day77.htm

There is still lots to do before the next NSWRA launch. We're currently working on the parachute deployment mechanisms. We decided to use two of our existing parachutes for the booster so we will save some time there.
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A little bit of pyro

We bought our 10 year old son a bigger pyro rocket for his birthday this year. He wanted something a little bigger than the Thunderbee he has flown several times on a 1/2A3. We bought him the Praetor from Suburban Rocketry.

Slowly over the last few weeks he actually built most of it himself, with a little help to get things lined up from dad. He did learn quite a bit about how a pyro rocket gets put together and the different materials and construction techniques needed compared to water rockets. He also learned quite a bit about the painting and extensive sanding process. It was just as much interesting for me to see how pyro rockets are put together. He chose the following colour scheme and spray painted it also mostly himself:


We had some decals from old model planes so we put those on to give the rocket a bit more character. We're hoping to launch it this upcoming NSWRA launch event on a C6-5.
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Staging mechanism assembly

This week we have been continuing with the staging mechanism of the Acceleron V booster. We've also made the non-return valve that fits inside the long PVC pipe. The valve was adapted from the old Acceleron booster that was mounted in a bottle cap.


More information and photos of the build can be found on the Australian rocketry forum here: http://ausrocketry.com/forum/viewtopic.php?t=1552

It hasn't all been smooth sailing though. After test assembling the base plate in the launcher with the actual booster segments fitted with their nozzles we discovered that the central mechanism couldn't go down far enough to lock into the mechanism. Not wanting to machine up a whole new central nozzle, we decided to put a thick plastic washer underneath it on the base plate, and using somewhat longer screws to hold it all in place was enough to resolve the issue.

The other issue we had was while trying to fit the hose on the end of this central nozzle we found it a little difficult, so we decided to machine down the hose connector a little bit to make it easier. While machining the small thin tube caught on the knife and unceremoniously bent, and was damaged. While trying to straighten it, as suspected it snapped off. Dad came to the rescue and machined off what was left, then proceeded to cut a thread into the mechanism and made a new separate hose connector component that simply screwed into the end. We epoxied it in place and all was good again.

We've also had discussions about how we are going to make the top bracket that holds the boosters together. It's going to involve steam.... but more on that later. :)
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Building continues

We have been continuing with the development of the booster. Here we test assembled some of the components to check for clearances and get an overall idea of how it will go together. The nice thing is that it just fits inside the house. (one inch from the ceiling)

One thing that was very evident is how high the top payload is, and we are going to have to move the flight computer down, or at least extend the Arm button down where it can be reached.


Pictured along with the rocket is a standard sized kid. Simulation says that the booster alone would lob him about 4 meters into the air. :)

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Acceleron V construction

Most of this week has been spent making the base plate for Acceleron V. Here it is partially assembled:
The sustainer air supply and retention mechanism still needs to be machined, which will be done soon.

The bottle splicing is also complete, although the bottles still need reinforcing around their necks. They also all need to be pressure tested. We made a number of spare spliced bottle pairs should any of these leak. We will give all the splices at least 1 week to fully cure.


We used PL for the splicing and Sikaflex for sealing the joints as we had leak issues when making spliced pairs for the Polaron rocket a couple of months back.

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Launch Report update

We've posted an update from the last launch day on our main website here:

http://www.AirCommandRockets.com/day76.htm

There are a number of photos from the day as well as some more design details of the Acceleron V booster build. We are pretty much now focused on getting the Acceleron booster completed. While we are aiming to have it ready for launch at the next NSWRA launch event, it may likely slip until the next one.
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Windy

We only flew a couple of smaller water rockets this weekend at the NSWRA launch day event, mostly due to the high wind conditions. A few of the pyro rocketeers lost their rockets somewhere over the adjoining suburb, so we decided to call it quits a little earlier too.

I'm putting together the launch report at the moment which should be available in the next few days. It also includes a progress update on the Acceleron V booster.

We did launch a couple of small pyro rockets with the boys and safely recovered those. During the week we bought a bigger pyro rocket kit from Suburban Rocketry so we are now building it with the boys in between all the other rocket stuff. I can see we'll probably be building a few of these as they are fun to build, but the cost of motors is pretty high when compared to air and water. :)

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Acceleron V modelling

This weekend we spent a bit of time modeling Acceleron V to scale in 3DS Max in order to figure out the spacial relationships of the new release mechanism and the position of the staging mechanism. We now have a clear idea how to build the base support mechanism and what clearances are needed. The images below include the second stage, although the colour scheme will most likely be different.

The length of the second stage has not been determined yet but will be such that the entire two stage rocket is stable in flight.

The rocket is designed to be launched from our drop away booster launcher.


Detail of the release mechanism and the location of the staging pod. The pod contains one of our flight computers and uses a standard 9mm Gardena release mechanism to release the second stage. Depending on the length of the second stage, the pod can be moved further up the rocket.


Fabrication of the booster segments continues, and we now have a materials list for the release mechanism so we can start construction on that as well. The staging pod is already finished. I'll post actual build pictures next time.

We've also been preparing our rockets for the next NSWRA launch day. There are no major new rocket changes although there are some experiments we want to run in getting more stable descent video as well as flying the whistling nozzle. After the last crash the Axion rocket has been rebuilt.
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Acceleron V Redesign

We've been collecting 2L bottles from friends and family over the last couple of months to make up more spliced pairs for the new Acceleron booster. After we had a few leak problems with the last spliced-pair batch we're now trying the sikaflex glue as a sealant in the joint area but PL premium as the main glue that holds the splice together.

Some of the 2L bottles ready for processingBottles cleaned, trimmed and curled ready for sanding.

All up Acceleron V has three segments in the cluster and each segment uses 3 x 2L spliced pairs giving a total volume of almost 33 liters. Up until now we have been using 10mm nozzles on the Acceleron boosters but with the larger volume and larger weight of water we have decided to go with the larger 13mm nozzles we use with our drop away boosters. Including the second stage, the total liftoff weight is now going to be approaching 16 kilos. Switching to the new nozzles would have also meant that we would have to machine new nozzle seats for the old Acceleron launcher.

Instead we decided to adapt the booster launcher to work with the Acceleron rocket. The old Acceleron rocket uses a speargun release mechanism, so we are replacing this with custom made aluminium gardena nozzle mounted on the baseplate that holds the cluster together. This nozzle will fit into the existing Gardena central release head.

Because this launcher's minimum nozzle spacing does not allow the three segments to be up against each other like in the old Acceleron rocket, we are going to separate the cluster segments further from each other. This will require a new baseplate for the cluster. This again will be made from aluminium and reinforced with fiberglass. By separating the cluster segments we will be able to lower the second stage release mechanism pod further down in between the segments allowing the second stage to also sit lower in the booster. This will help partially solve one of the problems we've been having with the old Acceleron rockets, namely the stability of the second stage on the end of the staging mechanism. The length of the Acceleron booster and the location of the staging mechanism prevented us from making the second stage any longer. If the second stage had been much longer there was the danger of snapping the rocket at the staging mechanism during the boost phase. By lowering the second stage between the segments, we can use the segments themselves as guide rails for the second stage. This will allow us to build a second stage around the length of an Axion or Hyperon rocket.

The second stage will be pressurised through the central release head allowing it to use a different pressure to the 1st stage. The Acceleron parachute(s) will now be located in the space between the spliced pairs.

With the second stage supported by the segments, it will also mean that the second stage can have a boat tail for better drag efficiency.

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Parachute Detachment Mechanism

In chatting to Mat G. this week, he described how his rocket got stuck in a tree flying one of the computers. I thought that the FC should at least be able to try to help in such a situation. Snagging a parachute on trees is a very common problem, especially when the wind carries the rocket beyond the designated range.

We put together a Parachute Detachment Mechanism prototype (DetMech) that allows the rocket to automatically let go of the parachute cord after a predetermined time.

The full details of the mechanism are available here:

http://www.AirCommandRockets.com/howitworks_3.htm

We want to test fly it next to see how the clamp holds up under high speed deploys. ... yup just another excuse to fly more rockets. :)


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FC V2.0 Development

With the last of V1.6 sold yesterday, we are using the proceeds of the sales on the development of the next version of the FC. The new version is quite different and includes a lot of new functionality some of which is intended for use on pyro rockets.

We are also aiming to reduce the overall footprint and weight of the FC by using surface mount components. Circuit design is about 2/3rds done but the software spec for this version is only about 1/4 complete. The core is still based around the PIC16F628A but will have a few more support chips to offload some of the functionality.

The expected time to completion is likely to be around 6 months as there is a lot of new code to write, but that may be pushed back further depending on time allocation priorities on all other projects currently under way. I'll post progress updates and more details when significant milestones are achieved.

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Flour Rockets

We've had a bit of fun this weekend with the kids launching rockets powered with flour rather than water.

The full write up of the days events is here:
http://www.AirCommandRockets.com/day74.htm

Included are photos and a highlights video.


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Variable Nozzle Testing

This weekend we pulled out the static test stand and continued with more testing. Before the tests we spent a couple of hours making the flexible nozzle membranes and the tools to make them.
Dad machined up the stamp tool that cuts the membrane out of the rubber sheet to the exact size (the brass component), and then the hole punch alignment tool, that allowed us to center the hole punch in exactly the middle.

We ran about 14 tests with different materials and different sized holes. We haven't had a proper look at the data yet, as that will again take a couple of weeks to analyze and write up. One interesting surprise we did get was during one particular test the nozzle made a pretty loud whistling noise. We might fly that one on the next launch day just for fun.

We'll post the full data on the nozzles when the analysis is complete.
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Day 73 - Highlights

We've posted an update on our main website with the highlights from day 73. The update includes photos and a video of the days' events.

http://www.AirCommandRockets.com/day73.htm

.... now it's back to the workshop....
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2 great flights, 2 crashes

We had an overall great day at NSWRA's launch event on Saturday. We got to fly the newly rebuilt Polaron VIb rocket that hadn't flown since May last year. Both flights were almost perfect with very nice vertical flights, and no spin which made for great stable ascent video. Although we had tested the bottles to 130psi, we only launched at 120psi to be on the safe side. During testing earlier in the week, we had 3 out of 4 spliced-pairs leak. So only the bottles that had withstood the full 130psi were used in the rocket. We were very happy with the performance of the rocket, and were glad that the stability improving changes we made had been effective.

While other NSWRA members were drilling holes in the clouds (literally) with their impressive pyro rockets we were busy taking core samples near the launch pad. One was the FTC rocket and the other was Axion II. Full details of the crashes will also go in the update.
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