Unome wrote: ↑
September 7th, 2019, 1:56 pm
Jeff knows from personal experience. It's possible some events have rules written primarily by one or two people, but I know that doesn't happen for Physics events at least, and very confident that the same is true for Tech events given what I've heard.
I'm a member of the tech committee. Before rewriting events, we spend 2 days or so reviewing the results from the previous year, FAQs, clarifications, and tournament feedback. The committee typically reaches a consensus on the overall changes for the next year. Then 3-4 people take that input and write a first draft of the rules. After they've been written, they are reviewed again by the 20 odd members of the committee. Further reviewed by the senior leadership. Then dry runned at SOSI where we get the input from folks who HAVEN'T been part of the rules writing, incorporating suggestions as appropriate. Then final draft and final review before publishing.
All that's part of the reason I'm so careful about answering clarification questions with LOTS of caveats and as undefinitively as possible. Even when I'm the event supervisor I'm only ONE of the people who help make the decision.
Also why I caution folks not to worry too much about the details of next year rules. They aren't even finalized till sometime in August.
SO, now, lets discuss how you deal with the rules this year
, cause they are what you have to work with!
Typically these planes are trimmed by multiple twists and turns on various parts to maintain a steady turn through the varying power from the prop. What are these, and which can you change on the floor?
Classically we have these planes turn left to deal with the prop torque. This means we typically have the following settings.
Prop thrust down and left.
Wing longer on left side than right.
Left wing washed in wrt the right.
Rear stab tilted left side high.
Now, which of those can you change on the floor, and how?
- Prop thrust. I see this one as hard. So much force you typically have to lock it down pretty tight. So what do you do? Not sure, but I'd probably trial no left thrust.
- Wing longer on left. How hard to change depends on the design and how you mount the wings. I typically use tissue tubes on the fuse with wing posts firm to wing. I could see a design change that fixes the posts to the fuselage and has two sets of tissue tubes on the wings providing appropriate offset for each direction. Alternatively, keep the tissue tubes, but two sets, one on left side of fuse, one on right. Maybe with an spacer to get more change.
- Wing wash in. Same design change would allow you to change this. Tilt the tubes on the wings such that they twist the wing as needed.
- Rear stab tilt. I've designed planes in the past with adjustable stab tilt. Tail boom was attached to fuse with a tissue tube. Two choices. One, make it a round tube you could adjust as needed. I don't like that, too easy to get it wrong in heat of competition. Alternative, two 'square' tissue tubes. Again, pre-tilted as needed.
- Left rudder. I actually fix the rudders on my designs. left rudder is from the angle of the tail boom. Previous solution would allow this.
How to go about figuring correct settings. Frankly, I wouldn't try to make the first plane that complicated, even for an experienced builder.
I'd build two planes. Trim one to turn left, the other right. Figure out appropriate trim settings to optimize flight time. Then use that info to build the 'adjustable' plane.
Oh, and yes, for first time competitors, focus on making a conventional plane turn left and maximizing its time. Only move onto right turns AFTER you have the experience to do that.