Raw Tournament Times

[jander14indoor]

Top time at Michigan State SO tournament this year 3:40, normal wing, straight time.
Ceiling height was 21 ft and the ceiling was acoustic tiles, fairly smooth and friendly to ceiling bumping.

Didn't see the flight a I was running arbitration in the tournament headquarters. So I can't say if they did anything other than ceiling scrubbing to maximize the time. And I don' know if that team is going to nationals, awards ceremony is probably just wrapping up.

But with 3:40 in that low a site, I'm going to predict it will take more than 4 minutes to win nationals!!

Jeff Anderson
Livonia, MI

[DoctaDave]

Do you think we'll be able to see a 5 minute flight in a sixty foot flying site since so many teams are close to 4 minutes already in 20-30 foot site?

[calgoddard]

Yes, I think there is a good chance that a team will put up a 5+ minute flight at Nationals this year in terms of actual flight time.

However, that team may end up being beaten by a team flying with the small wing chord bonus, as occurred at Nationals in 2010.

Here is a link to the video of the 5+ minute flight that was second place that year:

https://www.youtube.com/watch?v=Wqt-FsekeqE

The highest score wins in Wright Stuff, not the highest flight time.

[bjt4888]

I observed all of the best Wright Stuff flights at the Michigan state championships yesterday and quite a number of teams presented themselves very competitively. It was the team that I was coaching from Holt High School that won the Michigan State Championships with a flight of 3:41 in a 21' 4" ceiling gym. We were lucky to have an excellent event supervisor and ES team. The air was very calm in a very old gym on the Michigan State University campus.

The ES team protected the one entrance/exit door from both sides and didn't allow any entry or exit during flying. The ceiling was flat tile and appeared to be scrubbable, but as the junctures between tiles presented a little unevenness, the best strategy ended up being to fly with only light touches on the ceiling.

The Holt HS team touched the ceiling lightly about 5-6 times. They also flew under the one missing ceiling tile and got punched by a downdraft to lose about 3' of altitude at one point. They flew the Freedom Flight kit with a Harlan bearing and custom rear hook and a "Goins Style" sanded/blade trimmed Ikara propeller with .058g/in 11/2013 Tan SS. Their max torque was about 1.0 in oz with backoff to 0.4 in oz launch torque. They have flown at this high level all year long (they won two of the larger invitationals in Michigan and won a regional that was almost as competitive as the states) and this was a well deserved win.

As with many other students, they put a significant amount of time and energy into their preparation. They had good understanding of the Bernie Hunt design spreadsheet and used it to do "what-if" analysis to determine starting data points for static stability margin. Their success thoughout this year was partly due to use of a relatively conservative ssm of about 19% and a relatively conservative decalage angle of about 1.8 degrees. This along with a minimal amount of left wing washin and a slight increase (over the kit setting) in tailboom offset (for right turn) and stabilizer tilt, gave them an airplane that could be gently and repeatedly touched to the ceiling without losing altitude and maintained a circle of under 25 ft. They routinely fly no-touch 3:45 in their own 28 ft. ceiling height gym. The other top times (unofficial and by my watch) at the Michigan states were: 3:11, 2:57, 2:52, 2:43 and 2:43. Also, my team from Haslett HS was one of the 2:43's for a sixth place (I think this was there place). Several of the teams tried a slightly aggressive ceiling scrubbing technique and at least a couple that I witnessed had a little difficulty with this strategy. The floor dimensions of the gym were 66 ft by 160 ft and the relatively narrow dimension resulted in some teams migrating to the wall while ceiling scrubbing. Hitting the wall resulted in big loss of altitude. I think that at least two or three of the other top teams would have flown similar duration to the Holt team if not for unfortunate wall contact.

If the Holt HS team hadn't had the one downdraft from the missing ceiling tile, they would have flown another 9 or 10 seconds (based upon the average descent rate during the letdown phase).

A significant share of the team's success is due to the excellent Holt HS teacher and the program she has put together over the last 25 years. She gets great turn-out and she energizes the students to seek excellence. The Wright Stuff team had a varsity pair and a JV pair and a number of support students (underclasspersons). This group built six Freedom Flight kits this year and tested many trim styles, propeller types and prop/rubber combinations. The two students that won the state gold medal were the best communicating team that I've ever coached. They made many excellent data evaluations and decisions in the heat of competition over the year. I'm sure that all of the other successful teams around the country had similar experiences and skills.

Thanks to the Science Olympiad organizers. The students had a great experience this year.

Brian T.

[calgoddard]

Brian:

Congratulations to you and your team on their success.

You taught your team the value of good engineering, preparation, and attention to detail.

Perhaps equally important, you taught your team how to evaluate data and make decisions in the heat of competition. In my experience, that skill often provides the winning edge in many SO building events, and particularly, in Wright Stuff.

[bernard]

Brian, congrats to you and your team on an amazing time, even in such a low ceiling!

Did your team have the state wing chord bonus for their flights at the tournament?

[bjt4888]

Bernard,
The 3:41 time i quoted above for the Michigan state champion, Holt High School, was my unofficial time from the watch on my smart phone. I must have been focusing so much on watching their procedures that I didn't start my watch properly. I talked to them a couple of days ago and their official flight time was 3:46 in the 21 ft 4 in ceiling height, w/ 5-6 light touches on a (sort of) scrubbable ceiling. This is a raw flight time and they were using the regional wing.

They did test their state wing airplane quit a bit, but never got it above 3:25 in their home gym (28' ceiling) and 3:25 would be the "break time" that would make the state wing better (205 seconds plus 20.5 = 3:45.5) than the regional wing flying a 3:45. At states, they were planning on flying the state wing plane on their second official flight with a very aggressive ceiling scrubbing strategy if they needed to do this to win. Their half motor tests at 0.8 in oz launch torque with the state wing were about 2:00 flying to a height of 20 ft. (this would produce a 40 ft climb with a full motor, or a very aggressive, long ceiling scrub) This would have given them a theoretical time with bonus of 4:24. Of course, they knew that aggressive ceiling scrubbing works about one time out of five. As their excellent teacher was able to sign-up for the last flight time of the day, the Holt HS team already knew that they didn't need to take the risky, aggressive, state wing with .8 in oz of torque flying approach. They executed their alternate strategy perfectly with a crowd of about 50 people watching.

Hopefully any teams that are going to nationals are doing 1/2 or 1/3 motor testing in their gyms to determine launch torque to fully use the 65 ft ceiling that the University of Nebraska is generously making available. You will note from the pictures of this site that it has a peaked ceiling, so the usable ceiling height may be more like 50 or 55 ft. If our team was going to nationals, they would not be launching at full torque, but at a slight backoff (maybe wind to 1.1 or 1.2 and backoff to .9). Remember, a 65 ft. ceiling is still considered a "low ceiling" site. Unrestricted, full torque flights would probably require a 90 ft. ceiling (or more). Test to confirm as every airplane is a little different.

Brian T.

[someusername]

Regarding Brian T's latest post, I have a few more questions.

My first question is how do you increase your maximum height exactly? The gym at my school is roughly 30' tall, but even at full torque we could maybe get a maximum altitude of 40' (more or less). What variables could we change to increase the height without hurting our time?

Also, would the torque of a motor change much the more it is used? For example, if i test a motor's torque before it's ever been wound up and then test the same motor after its been tested say 10 times, would there be any difference?

And congratulations on your great times at the Michigan State Tournament!

[jander14indoor]

Absolutely, the turns to a given torque change as you use a motor. Generally getting lower for same turns.

But you need to put that in energy terms to understand how to take advantage of that properly. For rubber motors you can calculate energy stored in a motor by plotting the turns on horizontal axis, torque on horizontal axis. The area under that curve is directly proportional to energy. Winding curve is your input energy, unwinding curve is energy available to keep the plane in the air. More energy = longer times.

Others have mentioned they get best results from a motor after it has been used once or twice. That matches with years of experience of AMA flyers.

What's happening is the motor is storing more energy because the torque is falling off slower than the increase in turns. This is particularly true for the first couple of winds where you get a lot more turns and only a little torque drop off.

However, as you continue to use a motor, torque continues to drop, but turns don't continue to increase. You start storing less energy.

PS, I encourage you to challenge all this by collecting some data, it will make MUCH more sense if you do.
Make up 3-5 motors as identical as you can.
Wind one taking torque data vs winds until it breaks. Plot it. This establishes the max torque for those motors
Take a second motor and wind to 90% of breaking torque and unwind taking data both ways. The area under the unwind curve is the energy available to fly.
Wind that motor a second time, same max torque. Plot again. Torque should be lower on unwind, but turns much higher. Figure the area again, see if it is more than first wind.
Repeat that sequence until the motor breaks. Compare results
Do that with a third and fourth and fifth motor (until you patience wins out, but hey, repeatability is a critical issue in science and engineering).

From all that data you should be able to see if you want to fly contests on new, once used, twice used, whatever motors! With NO guessing.

Regards,
Jeff Anderson
Livonia, MI

[bernard]

For those who don't have torque meters or the time/rubber to wind and break some motors for graphs, I've posted some of mine, but I've moved it to the Winding topic since I think it is more relevant to that topic.