Designing the new WRA2 pop bottle altitude record class

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Designing the new WRA2 pop bottle altitude record class

Postby WRA2 » Sat Jan 05, 2013 12:59 pm

As the poll recently taken shows, we will be replacing the WRA2 altitude challenge competition with a new altitude competition using soda pop bottles to construct the rocket. Please use this thread to comment and make proposals.

The Poll can be viewed at:
viewtopic.php?f=15&t=2068

Proposed changes for discussion will be listed in yellow

There should be separate divisions for reinforced and unreinforced rockets. The unreinforced class should allow lower cost "peak" altimeters. The rockets shall be single stage for either division.



I. WRA2 Altitude Challenge General Design Parameters
I. WRA2 Pop Bottle World Record General Design Parameters

    Division 1 (unreinforced): Rocket must be constructed using an unmodified pop bottle with a volume of no more than 2.0 liters

    Division 2 (reinforced): Rocket must be constructed using an pop bottle with a volume of no more than 2.0 liters but may be reinforced. The bottle must remain (bottle shaped rockets constructed without the bottle inside will not be allowed)

    Rocket must use Water as its primary reaction mass.
    Rocket mass cannot exceed 1,500 grams. This is the total dry weight of all flying components in a flight ready condition including the pressure vessel, fins, nosecone, payload bay, camera, altimeter, flight computer, deployment system, batteries, and nozzle.(no reaction mass)
    Water Rocket must use compressed ambient atmospheric air at no more then 200 PSI (13.79 Bar) as its energy. Other gasses have much higher compression ratios and there needs to be a baseline so the record is fair to all. (see section II for special rules regarding bottled air).
    Water Rocket must use compressed ambient atmospheric air as its energy. Other gasses have much higher compression ratios and there needs to be a baseline so the record is fair to all. (see section II for special rules regarding bottled air).

    Pressure Vessel and Fuselage of Rocket must be constructed from lightweight nonmetallic materials.
    Rocket must be launched from a stationary position on a fixed launcher. (Slingshots,trebuchets, catapults, cannons, and all other forms of launcher boost assist are forbidden). Launch tubes are allowed as long as the internal pressure of the rocket is the only supply of energy.
    Rocket must be completely scratch-built using materials which are not manufactured for model rocket parts. (with the exception of the Camera and Altimeter) Raiding hobby shops for nosecones, or fins, or any other pre-manufactured items is prohibited. (manufactured items that are not designed for rocketry such as wind up toys are allowed)
    Rocket must be completely scratch-built using materials which are not manufactured for model rocket parts. (with the exception of the Bottle, Camera and Altimeter) Raiding hobby shops for nosecones, or fins, or any other pre-manufactured items is prohibited. (manufactured items that are not designed for rocketry such as wind up toys are allowed)

    Rocket must carry onboard a commercially produced altimeter to document the maximum altitude of the flight. Ground based and/or timing based altitude measurements are too error prone and are unacceptable.
    Flight must be recorded by ground-based video to validate flight duration and recovery. It is required proof the flight actually happened. (if using bottled air is used then the 10 minute max pressure hold must be shown).
    Entire flight including apogee must be photographed by an onboard video camera. If using a peak altimeter then the ground video will also show the display of the altimeter as the rocket is recovered following each flight.
    For the pop bottle world record division 1 (un-reinforced) low cost "peak" altimeters will be allowed.
    For the pop bottle world record division 2 (reinforced) logging altimeters will be required.
    Record Altitude is calculated as the average of the two highest flights the rocket achieves within a 2-hour period (note: If using a peak altitude altimeter the average will be for 3 flights in 3 hours). This prevents dumb luck, the “perfect storm” scenario or false readings from giving a false record. Results must be repeatable!
    Division 1 will be allowed the use of "peak" altimeters
    This criteria was inspired by high profile competitions such as the Ansari X-Prize.
    The same rocket must be used for all averaged flights. The only portions of the rocket which can be replaced are expendable or consumable items. (batteries, tape, deployment chemicals, water, etc..) Items which are damaged in any record attempt must be repaired and reused. Any competing rocket must be sturdy enough to survive multiple launches and the recovery system must be robust enough to prevent damage. “Expendable” rockets are disallowed from competing.

II. Bottled Air Rules

    Only bottled atmospheric air is allowed. No exotic gasses, cryogenics or combustibles.
    Tanks must be certified. (copies of tank certifications will be provided and filling station receipt).
    All local laws must be complied with for handling pressurized tanks as well as any certifications that the operator may need will also be provided upon a record submission.
    To prevent "stomp rockets" the rocket must remain pressurized to full launch pressure (200PSI or 13.79bar) for a period of no less then ten (10) minuets. (The ground view camera will show both the tank and rocket on the launcher during this 10 minute period).
    Bottled air pressure source must be located at the minimum safe distance of 50 Feet (15 meters) from the launcher (this allows the bottle air pressure source to be safely controlled in the event of an emergency).

III. Safety Rules

    All WRA2 Water Rocket Safety Rules must be followed.
    All launched parts of rocket which travel over 6 meters (20 feet) in altitude must have a recovery system which limits their descent rate at time of touchdown at ground level to a maximum velocity of 10 meters/second (33 feet per second) This includes all pieces which separate or are shed off in flight. Fast falling rockets, boosters, debris, or rocket parts can be very dangerous. Recovery system malfunctions for any part will disallow any record flights.

IV. Pressure Vessel Rules

    Pressure vessel must be entirely fabricated by the rocket builder.
    Division 1 will require an unmodified pop bottle with a maximum volume of 2.0 liters
    Pressure Vessel cannot be constructed using any portion of an existing high pressure enclosure. (i.e. no Paintball tanks, CO2 tanks, SCUBA tanks, Propane Tanks, etc.). The object is to engineer and build your rocket yourself.
    Pressure Vessel and all external parts of the rocket may not be fabricated from metal. (see the WRA2 water rocket safety rules).

V. Reaction Mass Rules

    Reaction Mass must be primarily ordinary tap water.
    Thrust must come from expelling reaction mass, not from air discharge. That would be considered an Air Cannon projectile.
    Water Reaction Mass must fill a minimum of 20% of the volume of the Pressure Vessel. Token amounts of water added in an attempt to qualify an air cannon projectile as a water rocket are not allowed.

VI. Filing a Record Claim

    All record claims must be filed to the WRA2 Contest Submissions for public review.
    Items required:
    · Onboard video for all submitted flights
    · Ground videos for all submitted flights (including altimeter display upon recovery if using a peak altitude altimeter)
    · Raw altimeter data for both submitted flights (if using a logging altimeter)
    · Time and date for each flight
    · If using bottled air: copies of the tank and operator certifications

    Optional Items:
    · Design drawings
    · Detailed still photos
    · Simulator data
    Maximum file size 20MB per file
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Re: Designing the new WRA2 pop bottle altitude record class

Postby U.S. Water Rockets1 » Sat Jan 05, 2013 11:52 pm

This should be a really interesting new contest!
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Re: Designing the new WRA2 pop bottle altitude record class

Postby SaskAlex » Sat Jan 12, 2013 12:42 pm

I seriously think we should leave a pressure limit in place. Especially for the unreinforced class. And honestly, I think it should be around 100psi. The problem is that bottles vary considerably from region to region. In places in europe, super thick bottles are available that can handle high pressure. In Canada, all our bottles are thin walled, and you won't find a common 2L bottle that can handle much more than 100psi.

If there is no pressure limit on the reinforced class, it will become the same thing as class A- who can work with carbon fiber or other exotic materials and create a super high pressure rocket. There really would be very little difference between the two classes, except for shape and size of the rockets (and I believe USWR's X-16 only has a volume of around 2L, so it's really only shape that's different).
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Re: Designing the new WRA2 pop bottle altitude record class

Postby SaskAlex » Sat Jan 12, 2013 2:41 pm

Oh, and I think we should change it from "pop bottle" to "plastic beverage bottle". Do we really want to exclude juice and water bottles? Many of them do come in bottles that can withstand pressure. And many of them actually have better shapes. Here in canada, all of Coke's products have gone to oddly shaped 2L bottles with no straight sides. Not good for rockets. Sometimes you don't have that many choices for good bottles, and I don't think we should exclude any more in the rules.
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Re: Designing the new WRA2 pop bottle altitude record class

Postby WRA2 » Sat Jan 12, 2013 3:20 pm

SaskAlex wrote:I seriously think we should leave a pressure limit in place. Especially for the unreinforced class. And honestly, I think it should be around 100psi. The problem is that bottles vary considerably from region to region. In places in europe, super thick bottles are available that can handle high pressure. In Canada, all our bottles are thin walled, and you won't find a common 2L bottle that can handle much more than 100psi.

If there is no pressure limit on the reinforced class, it will become the same thing as class A- who can work with carbon fiber or other exotic materials and create a super high pressure rocket. There really would be very little difference between the two classes, except for shape and size of the rockets (and I believe USWR's X-16 only has a volume of around 2L, so it's really only shape that's different).


Hi Alex,

Welcome back and thanks for "breaking the ice" for this discussion (people are shy this year). You do bring up an interesting point about the Euro refillable bottles being thicker and able to hold more pressure. Remember that the thicker bottle will also weigh more than the thin walled ones. Since soft drinks also come in various shaped bottles, part of the challenge for this class will be to find the correct shape bottle to use. Will someone find a soft drink bottle that is taller and thinner and have an aero advantage? Will someone come up with an ideal nozzle size and shape to make their rocket fly the highest. Will the competitors in Europe complain that all they can get are thick walled bottles and that they are at a weight disadvantage if a pressure limit is desired for the unreinforced class. Pressure limit can be added to the discussion for the unreinforced class. The idea is to encourage participation by keeping construction time, cost, and effort down.

There should be a lot of difference between the "Class A" and the "reinforced bottle" classes. For the new reinforced bottle competition a unmodified soft drink container will need to be used to construct the rocket. No splicing, or stretching, shrinking of the bottle would be allowed. Since only bottles will be allowed, FTC, tubes, pipe, etc will not be allowed. Think of the bottle that Anti Gravity Research used to fly 1242 feet. It was a standard Canadian 2 liter bottle which was reinforced with carbon fiber. As a matter of fact the 1242 foot flight will probably be the target altitude to beat to set a new record for this class. The purpose for this class is to give people without access to FTC a class to compete in. Competitors in this class would have to use the bottle as part of their rocket pressure vessel (removing the bottle from a carbon fiber bottle shaped "shell" to save weight would not be allowed.

For both classes, a photo and description of the bottle used (with label still attached) should be required as part of the submission criteria.
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Re: Designing the new WRA2 pop bottle altitude record class

Postby U.S. Water Rockets1 » Sun Jan 13, 2013 12:10 am

SaskAlex wrote:Oh, and I think we should change it from "pop bottle" to "plastic beverage bottle". Do we really want to exclude juice and water bottles? Many of them do come in bottles that can withstand pressure. And many of them actually have better shapes. Here in canada, all of Coke's products have gone to oddly shaped 2L bottles with no straight sides. Not good for rockets. Sometimes you don't have that many choices for good bottles, and I don't think we should exclude any more in the rules.


Those Coke bottles have been here in the USA for a couple of years. None of them have a straight side, and every one has some kind of molded pattern or texture that makes splicing them impossible.
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Re: Designing the new WRA2 pop bottle altitude record class

Postby bugwubber » Wed Jan 16, 2013 12:17 am

For the unreinforced class, can you use multiple 20/24 oz bottles spliced together to create a rocket with a total volume of 2 liters? Or by unmodified, do you mean the pressure vessel must consist of 1 intact bottle (with no splices, no reinforcing with PET bands etc) that must remain in the form it was originally manufactured in? I'm all for a 1 bottle pressure vessel but two 20oz bottles connected with a robinson coupling tye splice can hardly be considered reinforced. Splicing two bottle halves together on the other hand, would meet the definition of reinforced.
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Re: Designing the new WRA2 pop bottle altitude record class

Postby bugwubber » Wed Jan 16, 2013 12:32 am

Setting the pressure limit above the common burst pressure for un-reinforced bottles seems to just be forcing everyone to push the pressure up each flight until the bottle fails. Using a lower pressure would allow everyone to focus on design. That does open the issue of gauge accuracy/tampering though.
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Re: Designing the new WRA2 pop bottle altitude record class

Postby WRA2 » Wed Jan 16, 2013 9:04 pm

bugwubber wrote:For the unreinforced class, can you use multiple 20/24 oz bottles spliced together to create a rocket with a total volume of 2 liters? Or by unmodified, do you mean the pressure vessel must consist of 1 intact bottle (with no splices, no reinforcing with PET bands etc) that must remain in the form it was originally manufactured in? I'm all for a 1 bottle pressure vessel but two 20oz bottles connected with a robinson coupling tye splice can hardly be considered reinforced. Splicing two bottle halves together on the other hand, would meet the definition of reinforced.


For the unreinforced class, the original intention was to use a single beverage container that was unmodified (aside from attaching fins, payload and recovery system), splicing, joining, reinforcing in any way would not be allowed. This is still up for discussion though. The idea for this class was that a competitor could easily and cheaply build a class legal rocket. Innovation would be through searching for the best shaped or lightest bottle, the best nozzle design or the lightest payload.

As I said before, this discussion is to get an idea of what people would want for a competition so none of the rules are set in stone yet. We will look at all the suggestions presented.

For a definition of reinforced, it should mean anything added to the bottle to allow pressures higher than the bursting point of the bottle alone. Examples would be wrapping in fiberglass tape, putting a second bottle over the first one, or wrapping with carbon fiber, fiberglass, or Kevlar cloth and epoxy).
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Re: Designing the new WRA2 pop bottle altitude record class

Postby WRA2 » Wed Jan 16, 2013 9:11 pm

bugwubber wrote:Setting the pressure limit above the common burst pressure for un-reinforced bottles seems to just be forcing everyone to push the pressure up each flight until the bottle fails. Using a lower pressure would allow everyone to focus on design. That does open the issue of gauge accuracy/tampering though.


Pressure limit is an interesting idea.Someone else mentioned it too based on the fact that some countries use "refillable" bottles which unmodified can hold more pressure than the standard bottles and that teams using them would have an advantage. What pressure limit would teams think was fair for everyone?
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Re: Designing the new WRA2 pop bottle altitude record class

Postby teper » Thu Jan 17, 2013 10:00 pm

A good Pressure limit is 100, but I agree with what someone said earlier about tampering with gauges.

Also, No matter what we do, it will put SOMEONE at a disadvantage.
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Re: Designing the new WRA2 pop bottle altitude record class

Postby bugwubber » Sat Jan 19, 2013 5:56 pm

I like the idea of specifying the pressure vessel can only be made up of 1 bottle for the unmodified div.

I would go so far as to say (for Div 1) "The only modifications allowed to the pressure bottle are 1. attachment of fins or other flight guidance structures; 2. Attachment of rocket body/nosecone in such a way that does not reinforce the pressure bottle; 3. attachment of a nozzle or launchpad mating device. Any other modifications to the pressure bottle are prohibited."

I think it makes sense to expressly prohibit that which is not said so that nothing falls into a grey area.

Some other thoughts-
Specify launch platform max height? Or perhaps just that the altimeter have ground level set while on the launchpad? (I haven't used one yet so not exactly sure how they are set)
Require pressure guage to be installed in the launch platform?
Can GPS chips be used to document height?
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Re: Designing the new WRA2 pop bottle altitude record class

Postby WRA2 » Tue Jan 22, 2013 5:26 pm

bugwubber wrote:I like the idea of specifying the pressure vessel can only be made up of 1 bottle for the unmodified div.

I would go so far as to say (for Div 1) "The only modifications allowed to the pressure bottle are 1. attachment of fins or other flight guidance structures; 2. Attachment of rocket body/nosecone in such a way that does not reinforce the pressure bottle; 3. attachment of a nozzle or launchpad mating device. Any other modifications to the pressure bottle are prohibited."

I think it makes sense to expressly prohibit that which is not said so that nothing falls into a grey area.

Some other thoughts-
Specify launch platform max height? Or perhaps just that the altimeter have ground level set while on the launchpad? (I haven't used one yet so not exactly sure how they are set)
Require pressure guage to be installed in the launch platform?
Can GPS chips be used to document height?


These comments are very helpful TH:

A few answers to your suggestions:

Altimeters (barometric pressure which are most common) determine ground by measuring the barometric pressure while it is on the launch pad and not moving so even if you launched the rocket from a rooftop or hill, "ground" would be from there and not where the actual ground was in relation to the launch pad.

Requiring a pressure gauge that is visible when the launch is filmed is a good suggestion. I believe we required it for the "altitude challenge" competition.

Use of GPS systems would have to be discussed and taken on a case by case basis based on their accuracy. Most barometric altimeters have a resolution of 3-5 feet. If competitors wishing to use GPS systems we would need to see the specifications and decide if they are accurate enough to be used or if there was a "margin of error" "handicap" for using one.
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Re: Designing the new WRA2 pop bottle altitude record class

Postby WRA2 » Sun Feb 03, 2013 3:10 pm

Hello everyone,

The 1st drafts are up for the new bottle competitions:

Unreinforced Bottle
http://www.wra2.org/WRA2_Unreinforced_bottle_Rules.php

Reinforced Bottle
http://www.wra2.org/WRA2_Reinforced_Bottle_Rules.php

Comments?

Also does anyone have suggestions for better names for the competitions.
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Re: Designing the new WRA2 pop bottle altitude record class

Postby SaskAlex » Sun Feb 03, 2013 7:18 pm

A minor grammatical error- "no more then 100psi" should be "no more than 100psi" (in the unreinforced comp.) and "no less then 10" should be "no less than 10 minutes" (under bottled air in both competitions). No big deal, but if we are reviewing, might as well change it.

More importantly- unreinforced class mentions "unmodified beverage container" while reinforced does not mention "unmodified". I think this was just because the reinforcement is considered a modification, but we should also consider whether or not the bottle can be modified in other ways. Can it's shape be modified with a heat gun? Can excess material, such as the threads on the bottle neck be removed? Allowing such modifications opens the door for anti-gravity style "stretched" bottles, which could end up looking more like an FTC if someone really got a technique worked out. On the other hand, rounding the bottom with a heat gun and a little pressure inside is something anyone can do, and it can be very useful. I think we should probably try to allow a basic modification like that. And while I'm on that note- should we allow bottom rounding in the unreinforced class? Like I said, anyone can do it. Also, it can allow you to use certain water bottles with flat bottoms, which would otherwise be unusable. Finally, many bottles will change the shape of their bottom significantly, just from being highly pressurized. We wouldn't want to disallow that, would we? I know it makes the rules more complicated, but we could say something like "the only modifications allowed are to alter the shape via internal pressure and the application heat (such as from a heat gun or hot water). The bottle may not be inserted into any type of mould when altering its shape". Just a thought.

As for names of the classes, I think simple is better. How about something like "bare bottle" and "open bottle"?