Elastic Launched Glider C

erikb
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Re: Elastic Launched Glider C

Postby erikb » May 23rd, 2013, 7:14 pm

Also, if you make the bonus time somewhat random that's a lot of data collection. A big flight log. Comparable to a good teams GV log.
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elg4
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Re: Elastic Launched Glider C

Postby elg4 » May 23rd, 2013, 7:15 pm

Hey guys, I’ve been reading through this thread and I’m not quite sure why everyone is suggesting all of these potential changes. Like what is the issue with the current rules? I agree that the event is based on luck a little more than it should be. However, I do not believe that the current competition rules are based on who builds the lightest glider, or who gets to trim the longest, or who has to travel the shortest distance to arrive at the competition, or who gets the luckiest with their official flights. If teams want to build a risky ultra-light glider, versus a heavier, safer glider with less potential, then go for it! But they should be willing to accept the risks that go along with that, including potential damage.

As for the kits issue, I wholeheartedly disagree with the claim that kits take like 10 trim flights with “no middle step.” My team used a kit, and must have trimmed during our team practices for AT LEAST 10 hours, launching hundreds of flights. To compare, I saw many teams at nationals with our same kit that was getting less than half of our time. Additionally, the kit we used came with parts for four gliders (we constructed all of them), and only one of them showed potential for 15-20 second flights, proving that kits require this “middle step” and an intense amount of trimming.

Finally, my suggestion to make this event more equal and less based on luck is to leave the current rules as they are, but add a testing (as in examination) portion (similar to maglev). The test could be a “what if” scenario test, including questions like “If your glider begins to stall, what are a few adjustments to make in order to fix this problem?” (answers ranging from add mass to the front of the fuselage to decreasing the up elevator on the horizontal stabilizer). The test could also include some of the aviation vocabulary used on threads and websites so often, such as incidence, pitch vs roll vs yaw, and up elevator. This test could also include questions about aerodynamics equations and concepts, such as Bernoulli's principle.

These are just a few suggestions that I have thought of. I really enjoy competing in this event and I hope it can be just as exciting next year as it was this year. Thanks! :)

erikb
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Re: Elastic Launched Glider C

Postby erikb » May 23rd, 2013, 7:21 pm

I agree with most of your points. The main difference between your suggestion and mine is whether to make target flight(s) separate. The only benefit about making it separate is so that teams are clearly aiming for best time vs target time. However, the top teams should be clearly aiming for one or the other. I like having the freedom to choose in case the one of target flight wasn't exactly as I wanted. At least 2 flights should be given in case some accident happens (you don't want one unlucky thing ruin your score). Then the issue is time since 2 additional flights would be at least 2 minutes.
Even then, I still think your idea is good and better than a prediction or just using more flights to try to compensate for the log.
The problem i see with one or the other is how low the bar should be for the bonus flights to be a reasonable bonus.

It has to be low enough that any team that works at gliders can achieve.

A great time is a drop of 1.2 seconds per foot. A good time is .9
At our state there were three teams at or above a good time. The most were about .5 to .7

One good flight will outscore one bonus flight by nearly double. Hardly worth the bonus.
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erikb
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Re: Elastic Launched Glider C

Postby erikb » May 23rd, 2013, 7:29 pm

Hey guys, I’ve been reading through this thread and I’m not quite sure why everyone is suggesting all of these potential changes. Like what is the issue with the current rules? I agree that the event is based on luck a little more than it should be. However, I do not believe that the current competition rules are based on who builds the lightest glider, or who gets to trim the longest, or who has to travel the shortest distance to arrive at the competition, or who gets the luckiest with their official flights. If teams want to build a risky ultra-light glider, versus a heavier, safer glider with less potential, then go for it! But they should be willing to accept the risks that go along with that, including potential damage.

As for the kits issue, I wholeheartedly disagree with the claim that kits take like 10 trim flights with “no middle step.” My team used a kit, and must have trimmed during our team practices for AT LEAST 10 hours, launching hundreds of flights. To compare, I saw many teams at nationals with our same kit that was getting less than half of our time. Additionally, the kit we used came with parts for four gliders (we constructed all of them), and only one of them showed potential for 15-20 second flights, proving that kits require this “middle step” and an intense amount of trimming.

Finally, my suggestion to make this event more equal and less based on luck is to leave the current rules as they are, but add a testing (as in examination) portion (similar to maglev). The test could be a “what if” scenario test, including questions like “If your glider begins to stall, what are a few adjustments to make in order to fix this problem?” (answers ranging from add mass to the front of the fuselage to decreasing the up elevator on the horizontal stabilizer). The test could also include some of the aviation vocabulary used on threads and websites so often, such as incidence, pitch vs roll vs yaw, and up elevator. This test could also include questions about aerodynamics equations and concepts, such as Bernoulli's principle.

These are just a few suggestions that I have thought of. I really enjoy competing in this event and I hope it can be just as exciting next year as it was this year. Thanks! :)
Trust me when i say this. My team would love to not have any changes to the rules.

You have already seen one post on here that it is a bad idea.

The discussion is how to get it more congruent with a scientific event where there is data collection and results. Then those results are used to compete.
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Poudre High School, Fort Collins CO.

jander14indoor
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Re: Elastic Launched Glider C

Postby jander14indoor » May 23rd, 2013, 7:39 pm

Hmm, popular discussion. Several posts since I started typing this. To late to re edit, so I'll post as is. This really belongs about 5 or 6 posts back up the stream. Looks still relevant though.

As the guy (as i remember, it did come from a multi sided conversation on how to get the importance data collection and analysis across without saying it) who first suggested flight logs I'll take a stab.

Good engineers and scientists use test logs because the recognize the critical nature of data. As mentioned already, the goal of this event is to get students to take and effectively use data. And if you look closely that's true of many of the tech and physics rules. So, we added the logs to the rules. Other events took other approaches. We still haven't really figured it out for bridges/tower/boom, but it is just as important there.

Once that was done the problem came in how to reward/punish behavior without making the ES task too difficult. Frankly we liked how easy it was to score the flying events. High time wins. Easy to measure, easy to rank. No fussy calculations. And we really weren't sure how it would work the first few years. Not sure what was important. And we didn't want to coach through the rules. So, we set a minimum requirement to get the idea across and a reasonably low penalty. Again, easy to score.

As chalker7 stated, it has worked pretty well, good teams have good logs and do well on average. Teams without logs seldom do well anyway. Its kind of self penalizing.

Now, we've done it for what, at least 5+ years now. Is it time to get more rigorous based on that experience? Maybe, lets hear suggestions.

But we should also agree on criteria to judge the suggestions before getting too attached to a proposal. When I'm writing rules I like to start with the goal of the rules before I get too far. Otherwise it's easy to get lost in details of an idea and forget why you started the journey. Its also easy, as already demonstrated, to get into unresolvable arguments without realizing you aren't even talking about the same thing!

Here are some I'd suggest:
Keep it simple to score, complicated calculations are subject to errors that only penalize students in the long run.
Keep it relevant to the task of duration.
Frankly, keep the score impact low until it has been proven.
Make sure it rewards the behavior we want to reinforce. What is that behavior?
Keep scoring open ended. Perfect scores just result in ties at nationals and I hated having to resolve a 8 or so way tie in robots last year, thus the height task!
Probably others. Your ideas?

Jeff Anderson
Livonia, MI

sr243
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Re: Elastic Launched Glider C

Postby sr243 » May 23rd, 2013, 7:51 pm

The problem i see with one or the other is how low the bar should be for the bonus flights to be a reasonable bonus.

It has to be low enough that any team that works at gliders can achieve.

A great time is a drop of 1.2 seconds per foot. A good time is .9
At our state there were three teams at or above a good time. The most were about .5 to .7

One good flight will outscore one bonus flight by nearly double. Hardly worth the bonus.
Yeah, I think around .4-.6 of the ceiling height is fine so like 8-12 s in a 20 ft gym. That way most top teams would have to calculate and practice to get that time while the middle teams would have to get at least get a good launch. Otherwise 5-10 seconds for regionals, 10-15 for states, and 15+ for nats seems fine to me. I think the bonus shouldn't be enough to make or break a team but push a team that practice a lot and mastered their glider over a team with a slightly better glider without much practice besides enough to get a good time. I think 10 seconds/points is enough. Since most good scores for 2 flights are around 30-60 seconds, 10 seconds is actually quite significant, enough to bump a team up a few spots. I don't think that just getting target time once should outweigh getting 2 very good flights.

So 2 bonus flights of up to 10 points for getting close of the target time sounds fine. Calculation would be easy, 10 - (percent error x 10). Another idea is just to incorporate the target times in the flights themselves so competitors have to choose whether to get closer to the target time or improve on their best time (makes the teams think about their options).

_HenryHscioly_
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Re: Elastic Launched Glider C

Postby _HenryHscioly_ » May 23rd, 2013, 9:24 pm

why was there no minimum weight this year?
Past flying events all had minimum mass required, right?
Doesn't that help, in that teams won't have to worry about spending money on buying the best balsa?

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Re: Elastic Launched Glider C

Postby wlsguy » May 24th, 2013, 3:57 am

As for the kits issue, I wholeheartedly disagree with the claim that kits take like 10 trim flights with “no middle step.” My team used a kit, and must have trimmed during our team practices for AT LEAST 10 hours, launching hundreds of flights. To compare, I saw many teams at nationals with our same kit that was getting less than half of our time. Additionally, the kit we used came with parts for four gliders (we constructed all of them), and only one of them showed potential for 15-20 second flights, proving that kits require this “middle step” and an intense amount of trimming.
The extensive use of kits was one of the things I noticed at Nationals.
The Freedom Flight kit was the most popular and the data analysis suggests they do not provide any advantage.
This is probably due to the time required to trim them properly.
Of the 24 teams using them the rankings were everywhere between top 5 and next to last with an equal dispersion throughout.

Analysis of the individual flights also showed some interesting points.
As the number of scored flights increased, the likelyhood of the rankings changing also increased.
This indicates many teams have good repeatable gliders when 2/5 flights are counted but this quickly drops when 4/5 flights are counted.

Since the goal is to have repeatable flights while maintaining maximum performance would it be better to award the win to the team who can make 4- 15 second flights in a row or the team who can make 2- 20 second flights combined with 2- 3 second flights. I would suggest the team with the lower performing but more consistant glider should win. What are everyones else's thoughts?

On the subject of ceiling heights; have teams been seeing this event run in short (less than 20') ceilings? I feel this is rare but have no data to support the opinion.

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Re: Elastic Launched Glider C

Postby chalker7 » May 24th, 2013, 5:30 am

why was there no minimum weight this year?
Past flying events all had minimum mass required, right?
Doesn't that help, in that teams won't have to worry about spending money on buying the best balsa?
Because there isn't really a benefit to getting as light as possible in this event. If you go too light, the glider isn't strong enough to be capable of being launched. You can easily reach the minimum effective weight with hobby shop balsa and go well below it by using foam.
In general, we prefer to have the rules be as open as possible and not ban things if there isn't a good reason. Having a minimum mass (in this event) is just a red herring teams would have to deal with and another thing supervisors would have to check.
National event supervisor - Wright Stuff, Helicopters
Hawaii State Director

erikb
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Re: Elastic Launched Glider C

Postby erikb » May 24th, 2013, 6:13 am

why was there no minimum weight this year?
Past flying events all had minimum mass required, right?
Doesn't that help, in that teams won't have to worry about spending money on buying the best balsa?
A sheet of 4.5# balsa that makes two 30cm wing span gliders is around $3.50 and easy to come by.
A sheet of under #4 balsa is around $7 and nearly impossible to find.

Yes, between the two the difference is a good glider vs. a great glider in the AMA world. But i would also point out that if you have the skills to work with any balsa that is under #4 you should be allowed to use it. It has little structural integrity and is extremely fragile. Especially if you are going to launch it.

If you look at WIF7 all that carbon tow reinforcement is because the wing would explode on launch without it. This year the kids at poudre got to the point where they understood and could work with 4.2# wood but, there were many heart breaks. 8 hours of sanding wasted because the edge of the sanding block or a fingernail gouged the wing. The first launch the wings exploding or a crash that ends the glider.

My only concern is without a minimum weight their might be too much parent/coach involvement. It's the rarity of the wood not the cost that makes me wonder if a kid was the one that built the wing. You don't get a lot of practice with a very rare wood. But, after thinking about it. There are just a handful of people in america that can work with balsa that light and make a competitive glider. And i think i would be unlikely they would build for a team.
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