Second Launch of JP-2

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SaskAlex
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Second Launch of JP-2

Post by SaskAlex »

JP-2, or "Just PETE- 2 stage" is the rocket I'm hoping to break the Class B record with. Last night I launched it for the second time, and the first time with onboard video and logging altimeter. The altimeter beeped out 1021 feet, but after looking at the data, it looks like that was part of a false spike. Actual apogee appears to be around 1005 feet.

I think I can still get some more pressure into it, so I've still got a chance at the record. However, I am having some small issues which might require labour-intensive changes to be made. Anyways, here is the onboard footage (shot with an MD-80 clone, http://www.hobbycity.com/hobbyking/stor ... k_Micro_SD, that I'm quite happy with). The parachute is too small to make for a good video on the way down, but I'm more concerned about recovering the rocket. I was at a pretty huge launch site last night, and the rocket almost drifted out of it, even with the small chute.

[youtube][/youtube]
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Re: Second Launch of JP-2

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SaskAlex wrote:JP-2, or "Just PETE- 2 stage" is the rocket I'm hoping to break the Class B record with. Last night I launched it for the second time, and the first time with onboard video and logging altimeter. The altimeter beeped out 1021 feet, but after looking at the data, it looks like that was part of a false spike. Actual apogee appears to be around 1005 feet.

I think I can still get some more pressure into it, so I've still got a chance at the record. However, I am having some small issues which might require labour-intensive changes to be made. Anyways, here is the onboard footage (shot with an MD-80 clone, http://www.hobbycity.com/hobbyking/stor ... k_Micro_SD, that I'm quite happy with). The parachute is too small to make for a good video on the way down, but I'm more concerned about recovering the rocket. I was at a pretty huge launch site last night, and the rocket almost drifted out of it, even with the small chute.

[youtube][/youtube]
Congratulations on breaking 1000 feet 8) using a WRA2 :WRA2: class B legal rocket. :D :D Would you like me to add your "personal best" to our standings page. :mrgreen:

You have joined a very elite group of water rocket scientists who have launched over 1000 feet.

:W Welcome to the 1000 foot club! :W
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SaskAlex
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Re: Second Launch of JP-2

Post by SaskAlex »

Sure, you can put this on the standings page. Better put it down as a 1005 feet though, and not 1021.
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Re: Second Launch of JP-2

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SaskAlex wrote:Sure, you can put this on the standings page. Better put it down as a 1005 feet though, and not 1021.
Done!

Did you know that it also broke the 300 meter milestone too :wink:
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Re: Second Launch of JP-2

Post by Daan.[D&P]Rockets* »

Can you please show me your altimeter data plot please. Because we had the same problem with a peak and a higher outcome of the altimeter. I would like to compare the 2 plots when i downloaded mine.
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Re: Second Launch of JP-2

Post by RaZias »

Congratulations for the record.

Could you post pictures of your rocket and characteristics ?
Like pressure, volume, weight...it´s reinforced by fiber-glass ?
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SaskAlex
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Re: Second Launch of JP-2

Post by SaskAlex »

RaZias wrote:Congratulations for the record.

Could you post pictures of your rocket and characteristics ?
Like pressure, volume, weight...it´s reinforced by fiber-glass ?
I do plan on getting pictures and giving some detailed specs, but I'm a little busy at the moment. Those will come when I either break the record, or give up. For now, I'll just give a little info. There's no fiberglass, just pop bottles (hence the name "Just PETE"). The booster is a 3 x 2L cluster and the sustainer is made from splicing heat shrunk bottles. The sustainer volume is probably around 2L. This last launch was done at 160 psi, and I hope to do the next at about 180.
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U.S. Water Rockets1
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Re: Second Launch of JP-2

Post by U.S. Water Rockets1 »

Congratulations on breaking 1000 feet Alex! Very few people have been able to do what you have done. It is a great accomplishment that you have achieved. The fact you have done it with just plain bottles is something that MANY people have tried to do and failed miserably at. You should be proud to have done something that nobody has ever done before! You are officially a water rocket master!
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thunderrockets
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Re: Second Launch of JP-2

Post by thunderrockets »

can i ask what cind of staging mech. and launcher you use if you don't mind?
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Re: Second Launch of JP-2

Post by SaskAlex »

thunderrockets wrote:can i ask what cind of staging mech. and launcher you use if you don't mind?
Here are some pictures of the launcher. It uses a Clark Cable Tie release for each bottle. The retention rings don't completely cover the cable ties when they are in the locked position, but only go about half way up the tie heads. This means the rings always want to come down on their own, so I don't have to pull them down to release the rocket but rather keep them up to hold onto it. This is achieved with the plexiglass piece which gets pulled out to release the rocket.
DSCI0070.JPG
DSCI0070.JPG (67.62 KiB) Viewed 146 times
Note that all three rings used to be ABS, but I lost one and had to replace it with the grey PVC one. There are two air hoses going to the launcher because the booster and sustainer are pressurized independently.
DSCI0073.JPG
DSCI0073.JPG (62.77 KiB) Viewed 146 times
Locked position
DSCI0071.JPG
DSCI0071.JPG (61.11 KiB) Viewed 146 times
Released position

Note the steel tube in the middle of the launcher. This goes up between the three booster bottles to pressurize the sustainer. It has a small plastic tube (the ink tube from a ball point pen) on the end. This tube fits snuggly into the sustainer nozzle (a bottle cap). Since bottle caps are fairly soft plastic, this actually seals all on its own. I do put a little bit of lube on the pen tube to make it easier to slide the nozzle on, though. The friction between this little tube and the nozzle, as well as the weight of the sustainer, is plenty of force to keep the sustainer on the booster during pressurization.

There really is no staging mechanism on this rocket. The sustainer fires right at launch. The only other important part is the way the booster supports the sustainer. For my spliced rockets, I heat shrink all of my parts over a form. With this method I've made a nice fairing for the sustainer. The booster has another heat shrunk PET piece that fits perfectly over top of this fairing. In other words, the end of the sustainer fits nicely into the top piece of the booster. Have a look at my most recent launch thread, http://www.wra2.org/forum/viewtopic.php ... 1080#p8318, for some pictures. Because of the shape of the fairing and the receiving piece on the booster there is no force holding the sustainer onto the booster, but as long as there is a vertical force between the the two stages, as there is during the thrust of the booster, the sustainer is kept in line with the booster. I can draw something up if that is hard to understand.

Alex
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U.S. Water Rockets1
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Re: Second Launch of JP-2

Post by U.S. Water Rockets1 »

Alex,

It's pretty interesting that the weight of the sustainer is sufficient to keep it from pushing up off the pen tube filler and it also doesn't leak because of the friction. That's not something most people would think to try. Other rocketeers would probably try to cobble some complex sealing scheme with a lathe or something. You're really making a case of the "KISS" (Keep It Simple, Stupid!) methodology.
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