decalage for gym with AC on

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jinhusong
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decalage for gym with AC on

Post by jinhusong » March 24th, 2019, 11:42 pm

Hi,

Just heard our state gym the air drift is so bad that last year the champion has to complain to discard the Wright Stuff scores.

What is the strategy for gym with AC on? I know we should have larger decalage, like 5 or 10 even? Move CG forward a lot? How about launching torque? Anything other tricks?

Thanks for your help in advance,

Jinhu

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Re: decalage for gym with AC on

Post by jander14indoor » March 25th, 2019, 7:38 am

Flying in clean air is nice, but as a former state tournament director I can tell you it can't always be arranged. Some sites don't allow it for bureaucratic reasons, some don't have the right personnel on site, some have computer controlled systems only addressable from a central location, etc. The typical response for such an appeal is 'equally unfair to all'. For those unfamiliar with SO practices. At most tournaments, instead of throwing out an event (and all the work the students put into it), the director will generally keep it if all teams have the same disadvantage.

Instead of fearing it, learn how do deal with it, as you are in asking the question. Several things you can do, some strategy, some trim.

First, understand how the air is moving overall. Don't fly first! If there is a practice session, use it to study the air. Maybe don't fly your best plane, but fly something that you can see how it is impacted by the air. Watch how other planes behave. If there is a lot of drift, figure out where to launch to give you as much time/room as possible before you hit a wall. If there isn't so much drift, look for where the vents are that cause a lot of movement, sideways OR down. Avoid launching so that you fly THROUGH those spaces.You should be doing this even when the air is off, because there is always SOME drift, but is especially important if there is a lot of air movement. At the regional I attended this weekend, the air was off, but it was amazing the number of students I saw who launched their plans directly under the lowest hanging obstruction in the gym! Lost at least two feet of ceiling height.

Second, consider trim changes with the following in mind. Narrow the circle slightly to give more distance from the walls. Adjust CG/decalage to give a more robust stability margin. When you do hit something you want to recover fast not lose a lot of altitude. You'll lose time, but increase the likelihood of a full flight.

Third, practice in a site with AC on. See how it affects your plane. Learn how to execute some of the above BEFORE a competition.

Fourth, the following strategy becomes even more important. For your first flight make sure you trim and launch to get a dependable, solid time, first time, every time. Even though your plane may be capable of say 2:30 under ideal conditions, its better to have at least one official flight at 2:00 and take second or third than to have NO flights above 30 seconds! Once you have that, GO for it on your second official. Open up that circle. Bang into those rafters. Take chances. You might get lucky and get that 2:45 you've been searching for. Note, times are just an example of the concept, not targets for your plane and venue.

Good luck,

Jeff Anderson
Livonia, MI
Last edited by jander14indoor on March 26th, 2019, 8:40 am, edited 1 time in total.

jinhusong
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Re: decalage for gym with AC on

Post by jinhusong » March 25th, 2019, 9:04 am

Thanks Jeff.

I printed it out and will study more and follow it.

Jinhu

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Re: decalage for gym with AC on

Post by coachchuckaahs » March 25th, 2019, 10:01 am

All great advice from Jeff.

While one would like a one size fits all solution, the air motion will be different in every room. Our regional was in a ball room, the vents blew straight down. Not terrible drift, but it was a small room, so any drift was bad. The main effect was a loss of several feet as the plane passed the vent on each lap. No way to avoid. No matter how much torque or how thick our rubber, we could not reach the 20' ceiling.

Last year, it was in a gym with angled blowers. We reached the rafters, but it was highly bouncy and unpredictable. Small circles were the best solution, but adding torque was not.

Be ready to make adjustments, use your data, and study the room.

Coach Chuck
Coach, Albuquerque Area Home Schoolers Flying Events
Nationals Results:
2016 C WS 8th place
2018 B WS 2nd place
2018 C Heli Champion
2019 B ELG 3rd place
2019 C WS Champion
AMA Results: 3 AAHS members qualify for US Jr Team in F1D, 4 new youth senior records

jinhusong
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Re: decalage for gym with AC on

Post by jinhusong » April 7th, 2019, 1:21 pm

Update:

We went to NorCal state yesterday and got second place, 2:53 raw time.

We prepared 2 planes. One with 5.0 degree decalage and very tight circle, the other 2.99 degree.

The AC is on and it blows 45 degree downward from many outlet on the ceiling. Ceiling height 32, clear 26.

We studied the air and watched like 5 people flew before us. Because schedule conflict, we cannot pick afternoon time slots.

We flew the 5.0 degree one first, hoping it can bounce down from ceiling or get push down from the air blow. Before it hit the ceiling, it got blew to side and and ended hanging on the only cable there. Just 1:46.

Second plane no touch, flew maybe 23' height, blowed up down and around, landed on a chair holding the yellow tape.

I was there almost all day, felt only Mountain View did excel job to study the field. They have drawing to mark the air flows and picked quite good location to launch. They also got very good luck. Both their planes barely missed the basketball stuff. One time, just went through a gap of less than 1 foot. They got around 2:40 fly time.

I missed watching Albany, probably they flew while I went to see our Boomilever next door. They got first place. I heard the time is quite close.

Overall, the strategy from you guys worked. I saw a few team used similar strategy as our first plane, they work pretty well. Morning slots were most empty and most team tried to get late slots.

Thanks,


Jinhu

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Re: decalage for gym with AC on

Post by Rossyspsce » April 7th, 2019, 1:47 pm

what should I be doing if my coach is forcing me to go and fly first for my state competition? The most I could hope for is getting a practice flight in first or another team beating us to the room. He is making me do this so that the varsity team can watch what happens with our plane, and so that I do not beat varsity by being able to study the room properly

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Re: decalage for gym with AC on

Post by klastyioer » April 7th, 2019, 1:59 pm

Rossyspsce wrote:what should I be doing if my coach is forcing me to go and fly first for my state competition? The most I could hope for is getting a practice flight in first or another team beating us to the room. He is making me do this so that the varsity team can watch what happens with our plane, and so that I do not beat varsity by being able to study the room properly
for one i would try to fly b4 the comp even starts but stay conservative for the time being
itll at least get some trims out of the way and give you a layout on where the drafts are
also you can fly two planes at once the rules never state that you cant so if you cant fly b4 the comp trim one plane get it up in the air and then wind as thats up in the air for the next plane
when the first comes down wind for a first official and then when the second plane comes down launch it
it sounds confusing but its somewhat manageable
you could just trim if u rly need to but thats up to you just try to do the best you can
it's not about the medals; go out there and have fun. make progress, learn a few things and have one heck of a time; that's all that matters.

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