Great Photos from Acceleron V flights

Andrew Eltobaji from NSWRA took some great photos of our 2 stage rocket from a month ago. He definitely has great skill in catching fast moving rockets in action.

See some of his other pyro rocket photos here: http://s278.photobucket.com/albums/kk99/elta100/ and click on the NSWRA folders on the left side.

Here are some of his photos from the day. I have included them here in their almost full resolution. (Blogger will not let me upload the full resolution.)  Be sure to click on the photos so you can zoom in and get a good look at the detail. I wish I could take good photos like that!



Flight #2

I'm actually not that close to the rocket ... telephoto lenses are great!

It looks like the red booster is a little late in starting its air pulse.

Blue food colouring in the water is a great way to contrast against the white clouds

Secondary (backup) parachute is being deployed.

Coming in for a gentle landing

Flight #1

Good laminar flow from all of the nozzles during the booster's water phase.

Without the blue colouring, things are less messy on the ground.

Rocket is suspended sideways to cause extra drag and land more gently.

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Fiberglass rocket flights

This week has been a very busy week in trying to get a couple of fiberglass rockets ready for today's Doonside launch. We ended up flying the smaller one four times, with some failures as well as some very good and promising results. There was a very strong wind at the launch site and so we decided not to launch the bigger rocket. We ended up launching the last rocket at 245psi - our highest launch pressure to date.

I'm in the process of putting together a launch day report again, which should hopefully be available in the next couple of days.
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Fiberglass pressure test results

We have now tested a number of glass reinforced spliced-pairs of bottles. The results so far look quite promising in improving the performance of our rockets. The extra weight of the reinforcing requires an extra 30psi to compensate, but the much higher launch pressure should raise the altitude considerably.

Next we need to assemble these into a proper rocket and pressure test it for leaks.

The full update including performance simulations is available here:
http://www.AirCommandRockets.com/day91.htm

The update also includes a progress build on our first MPR pyro rocket.
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Fiberglassing pressure vessels

Yesterday we had our first go at fiber-glassing some bottles in order to be able to safely increase the launch pressure. We wrapped one spliced pair with a single layer of glass and the other with a double wrap.

The bottle on the left has a single layer and the one on the right is double layer. The bottles are only spliced with Sikaflex 11FC glue for an air tight seal. We are going to give the splices a week to fully cure before hydro testing them to destruction. I'll post the results of these tests when they are available.

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Acceleron V flights Update and Video

I have finished doing the launch report for this weekend's 2 stage flights. The update is available here:

http://www.AirCommandRockets.com/day90.htm

The update includes photos, altimeter plots, flight event time lines as well as a highlights video.

Here is a view of the Doonside launch field.

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New personal records

We had a great launch day today at Doonside. We finally got the Acceleron V rocket with Axion IVb sustainer flying properly. ...ie. upwards and also not into pieces. We launched the pair twice on the day at 120 psi.

 Acceleron V taking off on its second flight.

The sustainer reached 787' (239m) on the first flight and 810' (246m) on the second flight. Our previous highest altitude was 637' (194m). We also set our longest water rocket flight time at 1:00 min.We were hoping to break the 200m mark with this flight, and got the 800' mark as well. We are going to have a good look at the data from these flights and see where we can make further improvements.

I will be putting together a main website update over the next few days with more details, video and photos from day.

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Comparing real world data to simulator data

We've uploaded the flight day 89 launch report to our main website here:

http://www.AirCommandRockets.com/day89.htm

The update includes pictures and video from the launch day as well as a comparison of acceleration data from a couple of flights and 3 water rocket simulators.

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Doonside launch

Over the past couple of weeks we have been continuing to build rockets, although a little slower due to other non-rocket related commitments.

This weekend we flew a couple of different experiments at Doonside. We wanted to flight qualify the Acceleron V sustainer testing the jet foaming tornado coupling insert in the process.

We also flew three test flights with Craig's pyro rocket flight computer. It didn't control deployment but was along for the ride to gather flight data. The data from these flights and simulation results for comparison will be published in the next main site update.

I'm still in the process of writing up the full launch report which will take at least a couple more days.

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Dual Deployment

On Saturday we had a good launch day at Doonside. We tested a dual deploy mechanism on a couple of smaller rockets, and even managed to explode one on the pad. We also test flew the MD-80 clone camera on 3 of the flights.

The full update is available here:
http://www.AirCommandRockets.com/day88.htm

The update includes, videos of both water and pyro action from the day. There are also a couple of updates on some of the other things we have been working on.

Photo: Andrew E.

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Acceleron V rebuild

We've made good progress this week in getting Acceleron V back on the launch pad. Early in the week we tested the new narrow nozzle seals to make sure they will hold up to the pressure. This was also a pressure test of the booster side of the launcher. During assembly we noticed that one of the nozzle seals was distorting too much when the bottle was tightened. So dad machined up a new nozzle seal cutter that was a little wider and we made 3 new nozzle seals out of harder rubber. These worked well during assembly and in the pressure test.

Pressure testing the new nozzle seals. You can see the fog in the upper bottles as we let the pressure out.

On Friday we pressure tested the sustainer release mechanism and air supply. During the test we noticed that there was a very minor leak (1 or 2 drops per second) in the release head. On closer inspection it looked like there were a couple of small vertical grooves in the o-ring seat. So we spent today replacing the Gardena release mechanism with a new one. We are letting the epoxy fully cure before doing another test.

We spent the rest of today re-assembling Acceleron back to its normal configuration,.

Attaching the fins with the use of a fin alignment jig.

There are still lots of little jobs to do on the rocket, but it's good to see it back together again. We will do an integration pressure check to around 60psi to make sure there are no leaks in the Tornado couplings without putting too much stress on the entire rocket.

Next major milestones include a re-assembly of the sustainer. Depending on our progress schedule we may fly it at this weeks NSWRA launch day to flight qualify it before it gets used with the Acceleron booster.
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Pressure tests

After a week of curing, yesterday dad hydro tested 5 of the new splices to go into Acceleron V. These ones had a slightly narrower sleeve than the previous 4 for ease of manufacture. The results were all good with the test having the splices hold 140psi for 30 seconds. There were no leaks and no visible stress marks.

I'm happy with the yield rate so far for these splices. We haven't had any leaks in the 10 we have made to date. I'm sure there will be the occasional one that will leak or fail, but so far it's a good start.

We now have enough of the splices to put Acceleron V back together again. We will do a nozzle seal check next by placing the lowest bottles with nozzles on the launcher held down via the baseplate and checking to make sure the new nozzle seals are good. We won't need to remove the nozzles after the test.

Because the new pressure switch is only a SPST type, we can't wire it directly to an LED like last time to tell us that enough pressure is in the booster. When this LED was ON (@~20psi) we knew the switch was activated and the flight computer was safe to arm. I'm going to update the software in the primary computer to give us a pressure switch status indication on the LED display so that we can tell when it's safe to arm it. Although we could get it to arm automatically when the pressure switch activates, I still prefer to keep the human-in-the-loop for these kinds of things in case we need to abort the launch.
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Flight day and progress

Last week we went to the NSWRA launch day as we wanted to see the egg lofting competition. We weren't going to fly rockets on the day as Acceleron V has been taking up all spare time, but we did put a couple of small ones in the back of the car just in case. We ended up flying a couple of them during the day. I'm putting together a couple of videos at the moment. One is just a short one from the day showing the flights, but the cloud cover made it difficult to get a good shot against the white clouds. The other video is a discussion about some of the components going into Acceleron V booster.

I'll do a short write-up over the next couple of days. Otherwise it's been a continuation with splicing all the bottles.

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1st splice phase complete

Last night we finished gluing the 12 x 2L and 10 x 1.25L spliced pairs with the Sikaflex glue. The splices went together quite quickly, but preparation took a bit of time because it included heat shrinking the bottles, curling the edges, cleaning with alcohol, sanding and applying the masking tape before gluing could begin.

 Next we need to glue on the outer sleeves with PL and then re-enforce them with the other bottles and glass strapping tape. This should happen over the next few days.

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Splicing, splicing and more splicing

With the recent flights out of the way, we are now solely concentrating on getting Acceleron V back in the air. The first thing we need to do is make up more of the new spliced pairs we have been testing. Over the last 3 months we have been slowly collecting bottles from friends and family, so now we have some 70 odd bottles ready to splice.

We will be making up a stock pile of spliced pairs, not just for Acceleron V but for other rockets. We are also going to have a go with the 1.25 bottles at making spliced-quads. 4 bottles spliced together with a neck at either end. This will give us ~4L in a 90mm diameter body. We'll still be able to join them using Tornado couplings, but they should give us a little more performance. If they go well in tests we may use them on Acceleron V's sustainer.

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In-line deployment mechanism

We've updated our main website with the rest of the flight day report from 10th January 2010.

http://www.AirCommandRockets.com/day86.htm

The update shows more details of the lightweight deployment mechanism we have been recently testing. The Tomy timer version weighs 35grams.

The update also includes a highlights video from the day.

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Mercury Switch Experiment Results

We've completed the write-up for the experiment. The full results are available here:

http://www.AirCommandRockets.com/day85.htm

I was surprised by some of the results while others were as expected. Included are pictures, altimeter graphs and a video of the entire experiment.

I was going to include the full flight day report from Sunday in this update, but because it was kind of long anyway, I decided to separate it. The rest of the flight report will be done over the next few days including a description of the lightweight deployment mechanism and a video of how it works.


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Flight MicroLab - Mercury Switch Experiment

One of the things we want to fly this weekend at Doonside is a small science experiment. The main intention is to demonstrate how mercury switches behave during flight. It is a very common question we get asked all the time. "Why not use a mercury switch to detect when the rocket tips over at apogee?" ... it's a reasonable question since the system works well on the ground.

I thought video taping what they actually do in flight should give people a better understanding why they don't work the way they think they should.

Experiment setup:

There is a small digital video camera looking through a lens at a set of three mercury switches. Two are mounted the way people would typically mount them and the other is mounted upside down. They are wired to an LED each so you can see when in flight they actually activate. There is also a light source (white LED) above them so the mercury can be clearly seen. There is also a barometric recording altimeter mounted on the side to correlate the activation timing of the switches vs altitude/speed.

The parachute will be set to deploy later than normal so we can see what happens through apogee and somewhat beyond. After we have flown it I'll post the results to our regular website again.



Here is the MicroLab before being installed in the rocket. The rocket will be a Polaron style rocket of around 9.5L. capacity. The rocket is made up of the old Acceleron V bottles so we will be launching it at only about 110psi.

Front view

Back view with power turned on

View from inside the experiment

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Preparation for launch day

Happy new year! Having had a nice break over the Christmas and new year we are back in full swing with rocket development.

The next launch opportunity is on Jan 10, so we are working to have a number of rockets ready for the day. One of the rockets we'll be testing is the new smaller and lighter deployment mechanism. It weighs less than half of the one we have been using.We'll test it on a small rocket first and then if things go well, we'll extend the rocket and try it at higher speeds and altitude.

We are also preparing a Polaron style rocket that will do a number of in-flight experiments.

Dad has finished upgrading one of our air control panels which will now be able to deliver two different pressures each up to 300psi. This will be useful for the upcoming re-enforced rockets to be launched at higher pressures.

Some goals for 2010 include:
- Getting Acceleron V back in the air on a number of flights, and pushing it to its limits.
- Finishing off V1.7 of the flight computer.
- Getting the website extension completed.
- Higher pressure launches.
- More instructional videos and construction instructions.


We hope everyone has many successful flights with their rockets this year.
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Pressure switch testing

I've posted the results of the pressure switch tests here:

http://www.AirCommandRockets.com/day84.htm



The switch seems to be working well so now it's onto finishing the rest of the spliced pairs and getting Acceleron V re-assembled.

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Acceleron V pressure switch

This weekend dad and I worked on the Acceleron V pressure switch. On Acceleron's last flight it did not look like the pressure switch(TDD2) worked properly, and the pressure switch(TDD) we were using before on the earlier Accelerons had been somewhat leaky.

The pressure switch is used by the primary flight computer to initiate the staging of the second stage when the booster stops producing thrust.

So we set out to try to make a more reliable one. (I think this is our 5th attempt at a simple and reliable pressure switch). In the photo below is the prototype. The hose clamps are only temporary for the first pressure tests. Also the cut off bottle neck at the end of the switch is only temporary to support the clamp.

We pressure tested the activation pressure and it was around 30 psi. That means that the switch will activate when pressure falls below 30 psi. This is a good value because the flight computer can delay the staging a little bit until the pressure is around zero.

We ran several low pressure cycles to test how well it activates. And the results were always repeatable. We are now gluing it together properly, removing the hose clamps, and when the glue has dried, we will test the switch to full operational pressure to make sure it can still hold up at the higher pressures.

I would also like to set up one of the booster segments on the thrust stand and simulate a launch with the correct amount of water and pressure. The segment will be fitted with the pressure switch so that we can see when the switch activates in relation to the thrust curve. This should allow us to then calibrate the small staging delay for the primary flight computer.

Once the pressure switch is fully tested, I'll do a full write up of how it works on the main website, but it is simple enough for most people to build.

Acceleron V has also been completely stripped down so we can start replacing the bottles with the new spliced pairs.

Deployment Mechanism development

We have also been working on a new deployment mechanism that uses in-line parachute deployment. The main criteria for this is to reduce the weight. Currently the standard nosecone and side-deployment mechanism we are using on a 90mm bottle weighs around 138 grams without the parachute, but it does include all the mechanical hardware, electronics and battery.

The new nosecone and deployment mechanism currently weigh 37 grams (including a servo motor) with the electronics and battery still to be added. The new electronics (FC V1.7) and battery will add about 20 more grams, so all together the entire nosecone should be around 60grams. The design also allows for potentially large parachutes and is also around 30% shorter than our existing designs.

When we've had a chance to test fly it a number of times, I'll again post full details.
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Day 83 Update

I've posted the flight day report from Doonside on our main website here:

http://www.AirCommandRockets.com/day83.htm

It includes a highlights video and photos from the day as well.

I've also updated the flight day report with findings from last night when I was pulling the rockets apart to give them a clean. (see the Update section) It turns out we had some heat distortion issues that we didn't know about on the day. The Polaron VII rocket also flew with a missing o-ring in one of the Tornado couplings!

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Flight testing new splices

Well it's been quite a while since the last update, but rocket development has been continuing although a little slower due to the holiday season coming up. Today we went out to Doonside to test launch the new spliced pairs to see how they behave under flight and landing conditions, as well as sitting in the sun for a while.

The rocket used all 4 spliced pairs previously tested to 140 psi. The rocket was launched a couple of times at 130psi, and the splices held out well without any significant issues. 5 more of these will now be made and fitted to Acceleron V.

I am doing a write up of the whole day along with a few other foam and flour flights we did on the day. I'll post photos and a highlights video in the next few days.

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Keeping neighbours happy

This weekend we were going to do burst pressure tests on a range of bottles, but blowing up bottles in one's back yard isn't something to get your neighbours excited about. We are always looking for ways to lower the noise during these tests. Having the bottle full of water greatly reduces the noise, but a little bit of air can enter the bottle as it expands and so the resultant explosion can still be very loud.

Sound suppression attempt #1:
We filled the bottle with water, and then placed the whole bottle in a small plastic bathtub, filled it full of water, covered the bottle underwater with a towel and held it down with two bricks. ....
Result: Big boom, tub split in half, lawn received a healthy watering.

Sound suppression attempt #2:

So we drove over to dad's house, filled the next bottle with water and suspended it about 1/2m below the water in the concrete in-ground swimming pool.

Result: Quieter boom but what was amazing was the fact you could feel the concrete shake under your feet with the boom! This was a bottle full of water with about 100mL of air in a large pool and it burst at ~160psi. The slow-mo video standing on a tripod on the side of the pool shows the blur as the shockwave hits shortly later followed by tiny ripples on the surface doing interference patterns for about 1-2 seconds. Obviously the shockwave travelled through the water and echoed around the pool. .... WAY COOOL! ... but not the objective. Could the shock wave damage the pool? Unlikely, but we didn't want to take too many more chances.Tiny ripples on the water are the sound waves bouncing around in the pool

Sound suppression attempt #3:
Dad brought out an old SCUBA cylinder with the bottom cut off. This aluminium tank has a wall thickness of about 1cm, and so we place the bottle in it, stuffed old rags in the hole, placed it up against a rock wall, put a bench, lead weights and seat against it to stop the tank from flying in the other direction, wrapped the tank in two layers of foam and burst the bottle ....
Result: A barely audible thud.
Subsequent tests showed that you really only needed the rags in the end of the tank to suppress pretty much all the noise. There was no need for the foam wrap, or weights to hold the tank down.

Putting the bottle in the SCUBA cylinder

Stuffing in rags to suppress the sound.

Tank is under two layers of foam and bench with weights is meant to stop the tank from flying away.

In the end 9 bottles were blown up, and the neighbours didn't complain one bit.
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So far so good ....

During the week we made up four new spliced-pairs of 2L bottles. Each has a capacity of around 3.15L. The splicing and reinforcing technique seems to be working well so far. The Sikaflex is doing its job sealing the splices.

Today they were all pressure tested to 140psi without any leaks, and the bottles and tape showed no stress marks. We are very happy about that. Having a good yield rate means we can produce more of these with less bottles.


Now they will all be assembled into a Polaron type rocket. The initial target launch pressure will be 130psi with a 15mm nozzle. While we are building this rocket we will continue to make up more spliced pairs for the rest of Acceleron. Some of these will also be converted into boosters.


I think I have an approach too now for the pressure switch, so I'll be doing some prototype work on that soon.
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Investigating water behaviour in flight

At Doonside this weekend we flew the Axion rocket again 3 times with a camera on the boom to try and get a better shot of what is happening in the lowest bottle in flight. We used food colouring to enhance the contrast and no foaming agent this time. We also painted the fins a neutral gray to prevent the auto-iris on the camera making everything else too dark.

The full launch report is available here: http://home. people.net. au/~aircommand/ day82.htm


Acceleron V

Since a few people have now asked about when Acceleron V is going to fly again, I might as well do an update. We are in the process of getting Acceleron V back in the air. There were a couple of issues that we really wanted to solve before trying again. The number one priority is getting the spliced pairs reliable enough to be able to launch with them and not worrying about being very close to the burst limit. The last explosion showed that the spliced pairs just weren't there yet. Even though they were tested to 130psi, they were obviously close to that pressure. Although we could fly the rocket at lower pressure, the rocket's flight envelope was really not designed for anything lower than 110psi. Ideally the rocket needs 130-140psi.

The need for stronger spliced pairs is the reason we have been doing the splice tests recently. If further tests with the new splice technique continue to go well, we are hoping to replace the existing spliced pairs with the new ones on the rocket. We have 4 new spliced pairs curing at the moment and we will hydro test them to 140psi. We will then make a Polaron style rocket and test fly them at 130psi. If the spliced pairs perform well in real life situations then we will make up more to replace those on Acceleron V.

The other issue is the pressure switch. We want to have a reliable pressure switch to detect burnout. The pressure switch we used on the first flight just wasn't reliable enough, and the old pressure switch (TDD) leaks a little. When these issues are resolved, then we will try to put Acceleron V up again.

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Splice test #3 - Sikaflex - Success

We did a successful burst test on the Sikaflex asymmetric splice with a PL attached sleeve. (splice #5) The bottle ends were also reinforced with a jacket made from another PET bottle and held down with glass strapping tape. We learned a couple of things from this test:

The Sikaflex works great as a sealant and the width of the sleeve was more than sufficient to hold the splice together.

The final burst pressure was 190 psi! This is a better result than was expected. The actual failure was due to the strapping tape breaking, weakening the bottle reinforcing and then ultimately bursting the bottle. The sleeve still held though. The normal burst pressure of these bottles is about 165 psi.


This is a photo of the splice under test. The needle on top of the bottle was added to see how much bottle distorts close to the sleeve.

I'll make up three of these splices next and see how reproduceable the results are. I won't be testing them to destruction but pushing them to 140 psi, for an operational pressure of 130psi in actual rockets. If the results can be replicated, it would give us a nice safety margin.

I do have good slow motion video of the bottle's distortion and ultimate burst. I'll post the video with the next main website update, as I am busy the next couple of nights getting ready for this weekend's launch event.
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Splice test #2 - Epoxy

After letting the epoxy splice sit for a week we pressure tested the spliced-pair to destruction today. At around 120 psi a small leak developed. We kept increasing the pressure until the splice failed at ~150psi.

This time it was the PET bottle that failed rather than the splice. It fairly cleanly tore itself off from around the edge of the sleeve. The epoxy glue though separated cleanly from the bottle that flew off. This means that the epoxy did not do as good a job of holding onto the PET, even though the 1cm x 1cm tests showed promising results.

The sleeve was glued on with PL premium.

We are now waiting for the sikaflex and PL to cure on the next splice test.

The reinforcing shells worked well and the bottles did not show any signs of stress in the neck area. We have taken them off again, and will use them on the next splice test.

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Bits and pieces

We've updated the main website with some of the things we've been working on over the last month or so:

http://home.people.net.au/~aircommand/day81.htm

The update includes discussion of the splice variants we are currently testing as well as details of my involvement in the rocket challenge on Channel 7's 'Beauty and the Geek - Australia'.

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Splice test 1

I tested the splice yesterday, but it sprung a leak at 130 psi, which was disappointing, but not unexpected for the first attempt. It was only 4 days since I did the splice so it may not have been quite long enough for a full cure of the splice. Except for the leak the splice held well though, and there were no stress marks on the bottles. All up the reinforced double-walled spliced pair was 3.15L and weighed 139 grams.

The reinforcing shells used on both ends of the rocket can be easily removed and reused for the next test since they are not glued, saving a couple of bottles there. They protected the inner bottles well during the test.

Having recently performed the 1cm x 1cm shear tests on the Araldite super strength epoxy, I've made a new splice using this glue last night, and it looks like it has a much better seal. It does not bubble up like the PL. I used very gentle heat from the heat gun to make it flow better into the corners once the splice was assembled. Tonight I'll add the extra outer sleeve and glue it on with PL.

If the epoxy fails, next I'll try the sikaflex on the inner splice for a better seal, and then again use PL for the outer sleeve.

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New Splices

We have been using the same symmetrical splice technique on our 2L bottles for a couple of years now, but I have never quite been happy with it. We have had quite a few failures along the way, and the no-leak yield hasn't been as high as we would like. This meant a lot of wasted bottles and wasted time. The other issue has been the relatively low pressures the spliced pairs could hold. 130psi has been the limit we could practically push them to.

We used to use 2.25L bottles as the sleeve since they fit well over the 2L bottles and no shrinking was required. But recently we have found that some of the 2.25L bottles don't fit as well as they used to so it has been difficult to use them as well. To try to stop the leaks we have been using a different glue to do the sealing in the joint and PL to hold the splice together but this made the process more complex and we still ended up with leaks although less often.

So we are currently trialing a different technique that will hopefully yield better results. The technique is not new but a combination of several different techniques used together. We are using just PL glue for this splice and only the one type of bottle. I'll post the full technique on the main site, but here is a quick run down:

We first heat shrink about 2-3 cm of one of the bottles using hot water so that it fits inside another bottle of the same type. Then curl the edge on a pan. This has the effect of giving a tight seal where the heat shrink section ends and meets the other bottle since they are the same diameter at this point. We sand and glue these sections together. We then make up a sleeve about 4 cm wide made out of the same type of bottle. Because the diameter is the same we simply cut the sleeve to turn it into a strip. We then use another section of sleeve about 4 x 4cm and glue half of it to the sleeve strip to cover the gap. We let the glue dry for a couple of days. Then we glue the sleeve strip over the splice to provide further strength to the splice.

The drawback is that inserting one bottle into the other means that the volume is smaller, but not by too much.

We have had to previously reinforce the necks of the bottles with rings made from other bottles, but it only strengthened the necks not the rest of the bottle. This time we are going to use Richard Wayman's bottle-on-bottle technique to not only strengthen the neck but a significant portion of the rest of the bottle.

Hopefully this technique will yield better sealing results and will be able to take higher pressures.

The glue is curing at the moment so tests will be carried out at the next opportunity.

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It's been a while since the last update because there has only been little rocket related development in the last two weeks.

Crestwood Fair and other stuff

Last Sunday I spent the whole day helping to man NSW rocketry association's stall at the Crestwood fair. David and Neville did a great job of organizing the stall and getting all the display materials together. We had all sorts of rockets on display, and I even brought along a couple of water rockets including the Acceleron V to sit in the corner. It was a fun day talking with people about rockets. Quite a few interested people stopped by for a chat. We gave out close to 50 fliers on the day, so we'll see how many people turn up to the next launch at Doonside.


Over the last two weeks there were also several birthday parties, accountants to see, kid's school concerts, and kids cricket games which meant a lot of time away from the rocket workshop. Now that the dust is settling down, we'll be back to more regular development. Dad is also back from Europe so we'll have more time to spent on developing the next set of rockets.

Work has also been continuing on the website extension. There is just a lot of typing to do, and it's taking a lot longer than I originally expected. There are around 70 pages on there so far.

New workshop
We had a long weekend this week, but instead of rockets I decided to concentrate my efforts on making significant progress on the new workshop under the house. The current workshop is just getting too small. Dad and I spent all three days putting up the internal walls, which I'm happy about, because those are done now and the ceiling is next. We had the electricians come in earlier in the week to put in all the power points and lighting, and we'll need them to come back to finish everything off after we have painted. There is probably 3 weeks or so more work on it, because we need to put in new doors, do the little trim bits to finish it off, and then fit it out with benches and shelving.

Coming up
Last week we've also made a booster for Paul's pyro rocket, so we are hoping to fly it this upcoming weekend if the weather improves. It will be our very first two stage pyro rocket launch.


We are bringing a couple of water rockets with us as well of course. We will fly the rocket with the camera mounted on the boom again to see if we can get a clearer view of the water behaviour in the rocket during flight. Acceleron V is currently slated to fly at the end of the month's NSWRA launch.
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A different perspective

We had a good flight day on Sunday at Doonside. Although the wind was fairly strong we managed to get 3 flights in.



The first flight was that of a modified rocket giving us a different perspective of the rocket. We were using the technique to investigate what happens inside the lowest bottle during flight. We mounted the camera on a long boom sticking out the side and looking back at the rocket and nozzle.

The full writeup with pictures and video of the flight is here:
http://www.AirCommandRockets.com/day80.htm

I want to fly this one again, but actually remember to put the food colouring in it this time for better contrast enhancement. The fins also need to be painted a darker colour to work better with the camera's auto-iris.
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Lots of progress, little time to write about it

Here is a quick update as there has been lots of stuff happening in the background but have had little time to do proper write ups on the main website.

Flight Computers
Flight computers V1.7 and 2.0 are coming along well. We are developing two different ones at the same time with different capabilities. V1.7 is aimed at providing a very simple, inexpensive and small solution to parachute deployment. Focus is on least number of components in a lightweight package coupled with a single 3.7g servo and a small 6V battery.

V2.0 is a more advanced version offering expanded functionality over V1.6, with extension modules that are also suitable for pyro rockets. V2.0 also offers a much more flexible programing model capable of sequencing complex operations.

One of the main design criteria for these flight computers is that they can be fully configured in the field without any special external equipment like keypads, displays or a laptop. Both are now using surface mount devices for smaller footprints.

Website Extension
A lot of writeup time has been spent doing work on the website extension. This is mostly why there has been fewer updates on the main site. Currently the plan is to go live with the extension at the end of September. Some of the recent write ups will be available with the extension.

Rocket development
Acceleron V is currently resting until dad gets back from Europe. I've gone and given it a bit of a service clean such as the non-return valve that was showing signs of corrosion, and generally made sure that everything was in order. We need to take two cars full of equipment to the launch site and it takes both of us to set it up and launch it, so it will wait until he gets back.

The new rocket I want to fly this weekend (Sunday) is also close to ready. I'm using the Acceleron launcher, (without boosters) as it already has provisions for the 2 meter guide rail, as the rocket design does not allow us to use our regular launcher.

Other projects
I've also been helping out with prototyping work for a paid rocket project which I can't post about yet, but it has been quite interesting and something different. This has also taken up quite a bit of my time over the last two weeks.

On top of that I am finally working again on the new bigger workshop under the house. I'm hoping the electrician will be able to come in this week for a quote for all the wiring, and then we can put up the wall panels and then it should start looking like a real workshop. :)

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How to make a nozzle tutorial

This weekend we've put together a couple of short video tutorials on how to make a 9mm Gardena nozzle. One of the issues that people have been reporting is that they are unable to get a hold of the older bottle caps with removable seals. The video covers an alternate source of caps that are suitable for making the nozzles:

http://www.youtube.com/watch?v=hiixdmrSEbA

The second video shows how to resolve an issue with some launchers as not all Gardena (and clones) quick connect fittings are created equal. The problem reported by quite a few people is that the nozzle does not lock all the way down into the launcher. The nozzle appears to be locked in position but releases itself as pressure builds. The solution is fairly simple:

http://www.youtube.com/watch?v=y56A9_sIelU


We did not attend the launch at Doonside this week because the weather predictions indicated strong wind and rain. When I woke up in the morning I saw that it was pouring, and decided to skip the hour long drive to the launch site. A number of people attended the launch but said the weather was less than ideal.

The good news is that NSWRA now has permission to launch 2 times a month at Doonside. So the wait time for doing bigger test flights is reduced.
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Acceleron Photos from 4th July

A big thanks goes to Andrew from NSWRA for shooting the following photos of the Acceleron V booster in flight. We didn't get any still photos of the launch on the day as we were busy shooting video. (click on the images for a higher res version)

In the first one you can see the turbulent flow from the red and blue nozzles, whereas the green nozzle has very nice laminar flow (seen further down the plume).

The second photo is my favorite one with the air pulse starting and the sun reflecting from the sustainer.

The last one shows the rocket shortly after staging occurred. The black fins of the sustainer are about to clear the nose of the booster.


I'll post some of the other photos of the flight in next main page update.

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Development continues

It's been a while since the last update so I thought I'd post about what we've been up to. In the last few weeks I've been catching up mostly on non-rocket related matters, but development has been progressing.

Acceleron Vc
The rocket is now mostly repaired. The broken ring brace was easily repaired with a bit of epoxy glue, and a new coat of paint. New separator rings have also been made and are currently having the servo and camera fitted. The only thing that needs to be done is for the whole rocket to be pressure tested again and re-assembled.

We are also making up a whole bunch of new spliced pairs of 2L bottles (we are processing about 40 bottles) to have spare ones ready in case some of the original pairs fail during testing. These will also be used for the Polaron rockets and new bigger boosters.

New rocket
We have also been building a new smaller rocket (not named yet) to try to better understand how foam and foam generation behaves during flight. This rocket was built small so that we can fly it at our local park. I'll post full details in the next main website update.

I've also been working on an extension to our website that hopefully will go live in the next month or two because there is still lots of information to enter and format.
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Day 79 Flight day report

We've updated our main website with the latest launch day report here:

http://www.AirCommandRockets.com/day79.htm

Included are pictures from the day and a couple of videos. We also discuss the new mini video camera we bought to replace the broken FCO2, and additional thermal testing we did on black Tornado couplings.

Photo: David Kelleher

I'm still putting together the pyro rocket highlights video which will be ready in the next day or so.

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Acceleron Vb CATO

We just had a fun weekend at Doonside. The weather was perfect for launching and so we set up Acceleron Vb with all the modifications for the next test flight. About 10 seconds from launch the booster exploded on the pad. It was quite an impressive boom to say the least. One of the spliced bottles came apart. Although quite a few pieces came off, surprisingly there was little damage caused to the booster and sustainer. Repairs are already under way to get it ready again for the next flight.

We got good high speed footage of the explosion (over the years we have learned to keep the camera rolling while pressurising). Photos and video will be posted on the main website soon.

Other than that we ended up flying Axion V three times with foam and all the flights went really well with good onboard video and altimeter data. We were a little dissapointed that Acceleron V did not get to fly (as a cohesive unit :) ) this time, but at least the repair bill will be under $5.
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Modifications Update

During the week we've continued to make the necessary modifications to the Acceleron V rocket.

The new nozzles are now finished and internally polished for better efficiency. The new nozzle seats and fill tubes are completed also. The new pressure switch is about half completed. Depending on how tests go with it this week we may need to use the old Acceleron pressure switch as a back up.

We still need to do pressure tests on the sustainer (today) as it has many new bottles. We will also do additional pressure tests on the new nozzle seats and nozzles.

We made a new fin alignment jig last week that is fully adjustable allowing fins of any dimension to be aligned with the rocket axis while they are glued in place. As a result the sustainer now has 3 new larger fins well aligned. The surface area of the fins is about 3x larger than the previous set.

We are now doing the final preparation for the next launch day coming up this week. The weather outlook for the next few days looks good, so we are hoping that will extend into the weekend.

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Acceleron V first flight

We've updated our main website with details of Acceleron V's first test flight here:

http://www.AirCommandRockets.com/day78.htm

The update includes photos and a video of the flight.


Although the flight didn't quite go according to plan, there were a lot of positives we got out of it, and obtained some valuable data about the rocket's performance. Reviewing the altimeter and video data we think we know what happened. We now have a plan for what changes we will need to make by the second test flight in a few weeks time. Luckily they are only minor changes.

Complex rockets take time to sort through the various issues as there are many things that can go wrong. Without flights like these we don't learn what works and what doesn't. Overall we consider the flight mostly a success.

I've also uploaded a highlights video of the pyro rockets from the launch day here:

http://www.youtube.com/watch?v=JBEqzpBVFV0

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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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