Bottle Rocket B

[A Person]

Yes, you can.

actually, no you can't. You can't have any part of the rocket move while inflight.

Ah, wait. Wow, misread what he said, mainly the second part about nothing coming off.

I really hope I didn't mess anyone up.

[SenseiSushi]

In response to some comments above, parachutes and other recovery systems are not "banned" per se, but rules prohibiting any "change of shape" pretty much eliminate any parachutes, spinning blades, streamers, deployed wings etc - from the looks of previous competitions, backsliding is the way to go. Someone posted a great description of their backslider several posts back.

Note: I don't have the official rules in front of me now, but your team should when they're building. Last year, some of my students built a rocket from a big Smart-water bottle - ignoring the rule requiring the bottle be from a carbonated beverage. That was a pretty big one they missed, and there are other, smaller details to be aware of.

Has anyone had success with a glider-type rocket? We watched an interesting video where a bottle rocket resembling the space shuttle went into a perfect slow spiral descent. Seems like a neat idea, but is it easy to achieve stability? Internal gyroscopes are (hopefully) beyond the realm of division B...

I'm not exactly sure what you mean by "glider type" rockets but most teams I have seen design their rockets to rotate/spin in mid-air to slow their descent.

[SPP SciO]

I'm not exactly sure what you mean by "glider type" rockets but most teams I have seen design their rockets to rotate/spin in mid-air to slow their descent.

https://www.youtube.com/watch?v=s_dHGZPN9dg This is what I was referring to

[SenseiSushi]

I'm not exactly sure what you mean by "glider type" rockets but most teams I have seen design their rockets to rotate/spin in mid-air to slow their descent.

https://www.youtube.com/watch?v=s_dHGZPN9dg This is what I was referring to

Okay, now I see what you mean. I myself have not seen this style at any invitational, regional, state, or national competition. Most teams go the traditional route, but this might be a good alternative.

[calgoddard]

The space shuttle bottle rocket is very cool looking.

Glider rockets are not a good choice for SciOly Bottle Rocket competitions.

Like Elastic Launched Gliders the wing incidence (angle) required for high speed ascent (without looping) is not optimum for a low speed glide.

The flight time of the space shuttle bottle rocket in the video is only about 20 seconds. Many 2L backslider rockets can beat that time by a considerable margin (5 - 7 seconds) if they don't carry an egg. Many teams at the SoCal state finals last year got over 25 seconds per flight in the Bottle Rocket event.

Plus, the space shuttle bottle rocket shown in the video has a Gardena fitting on the bottle. This constricts the water stream, lowering the force of the thrust but extending the duration of the thrust. A Gardena fitting is not legal under the 2016 Bottle Rocket rules.

Expect lower times this year in Bottle Rocket than last year as the weight of the egg will lessen the height at apogee and speed the rate of descent.

The winner at 99%, if not all, SciOly Bottle Rocket competitions this year will utilize the standard back slider configuration.

[SPP SciO]

The space shuttle bottle rocket is very cool looking.

Glider rockets are not a good choice for SciOly Bottle Rocket competitions.

Like Elastic Launched Gliders the wing incidence (angle) required for high speed ascent (without looping) is not optimum for a low speed glide.

The flight time of the space shuttle bottle rocket in the video is only about 20 seconds. Many 2L backslider rockets can beat that time by a considerable margin (5 - 7 seconds) if they don't carry an egg. Many teams at the SoCal state finals last year got over 25 seconds per flight in the Bottle Rocket event.

Plus, the space shuttle bottle rocket shown in the video has a Gardena fitting on the bottle. The constricts the water stream, lowering the force of the thrust but extending the duration of the thrust. A Gardena fitting is lot legal under the 2016 Bottle Rocket rules.

Expect lower times this year in Bottle Rocket than last year as the weight of the egg will lessen the height at apogee and speed the rate of descent.

The winner at 99%, if not all, SciOly Bottle Rocket competitions this year will utilize the standard back slider configuration.

Thanks for the analysis - it seems like it's worth playing around with, but I'd bet you're right. It seems somewhat unfortunate though - out of all the build events, this seems to have the most restrictions on effective designs, yet the outcome is likely swayed by uncontrollable variables, like whatever the air is doing when it's your turn to launch.

[calgoddard]

SPP SciO -

It is definitely true that if two back slider bottle rockets at the same competition are both well designed and well constructed, the longest flight time of these two rockets will often be determined by ambient air conditions in the launch area at the time of launch. These ambient air conditions can vary significantly in just a few seconds.

In the hobby/sport of outdoor free flight model airplanes, at serious competitions, sophisticated electronic equipment is used to monitor local ambient air conditions on a real time basis, and to determine the precise optimum moment for launch. Use of such electronic equipment (and delaying your launch for 5 - 10 minutes while you monitor ambient air conditions) would likely not be tolerated by an Event Captain at a Science Olympiad Bottle Rocket competition.

All you can do is build the best bottle rocket you can, and prove that it performs well on a consistent basis with practice launches. Then you must hope for a little luck at the competition. Keep in mind that a well designed and constructed back slider bottle rocket launched in poor ambient air conditions can often beat a poorly designed and/or constructed back slider bottle rocket launched in good ambient air conditions.

The prohibitions in the 2016 Bottle Rocket rules against the rocket changing shape or deploying any type of recovery system leaves the back slider as the only viable design for winning the Bottle Rocket event this year.

By way of background, I estimate that I have personally observed over 300 bottle rocket launches.

[12565853]

I'm having trouble finding bottles with 2.2 cm necks instead of the reduced 2.1 size. Does anyone have a suggestion for finding the right size bottle?

[Boombloxer]

Do you guys know anything good to use as a nose thing? I've been using ping pong balls and they're working fine, but I'm wondering if there is anything better.

Thanks- Boombloxer

[Fanglin]

I'm having trouble finding bottles with 2.2 cm necks instead of the reduced 2.1 size. Does anyone have a suggestion for finding the right size bottle?

I don't know what launcher you are using, but I always use a Mtn Dew 2L bottle, because of it's reduced weight, and simple design. Actually a lot of soda companies make bottles like that, but Mtn Dew is most common. Here is an image