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.

_________________________________

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.

_______________________________

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.

__________________________________________________

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.

________________________________________

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.

_______________________________________

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.
__________________________________________

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.
______________________________________________

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.

______________________________________

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.

__________________________________________

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.

____________________________________________________

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.

_________________________________________________

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.


________________________________________________

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

______________________________________________

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.
____________________________________

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.

________________________

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.
____________________________________________

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!

_____________________________________

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.

___________________________________________

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.
___________________________

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.
__________________________________