Astronomyguy wrote: ↑February 4th, 2023, 8:50 pm
I don't have any specific questions for this post but I feel like posting a progress update/venting about our performance at the Princeton Invitational today (I was at the same competition as CypherKat). Any general advice regarding my flights would be welcomed, though.
1. I've been practicing pretty much every day since my last update, and they have more or less been in the 40-80 second range. I polished up the imperfections on my plane one day (fixed rips with scotch tape, made a new HS with less loose mylar, etc. and found that it no longer flew well with my previous washin setting, combined with the fact that I did not precalibrate the decalage and CG from before the fix. The next day, I was able to hit an amazing time of 2:26 with the improved plane (CG, decalage, washin fixed) despite the plane being harassed by the HVAC system. I think it could have gone over 3 with a better venue in those settings. On the very next flight, the HVAC blew our plane into the basketball hoop, where it remained for a couple of hours until someone was able to get it down at the end of the school day, but then someone stepped on it and broke the plane in a couple of areas.
2. I fixed it up later that day (our last day before the invitational) but did not get to test the plane until the invitational itself. Using the plane's behavior from a couple of dud flights, I was able to get it up and running, but I did not have much time to practice as the 10-minute official time blocks took up the entire block back to back, with no space in between. In a large ceiling (30 ft) and necessitating a tight turn, I tried to trim my plane so that it would climb well. For my first official flight, the circle ended up shifting and the plane crashed and broke. Using CA I repaired it within 2 minutes and got a second official flight in. I moved the CG back and it had a better climb, but the circle shifted and it crashed again. Both times were around 1:10/1:20, but the second one definitely could have neared 2 minutes if not over it had it not crashed.
Here are a couple of things I noticed:
1. One of our rubber bands (Apparently, our only near-max mass one with a proper knot, bad decision to use and mix up my rubber previously) broke after I tied and winded it. I don't think this was a lube problem, it was one strand that repeatedly broke free from the knot or snapped (not sure which). I had to borrow rubber from our A team and constructed a good rubber band from .094 weighing 1.95. I wound and unwound it twice to break into it (is this the right thing to do?) and that was how our official flight was saved.
2. Our plane couldn't climb more than a couple of feet above where it was thrown. I think this is just a CG/decalage not being optimized issue, as well as torque not being optimized (we finally got our torque meter assembled but couldn't get it to work)
3. Circle shifting. Really is a sucker; the plane usually settles after a circle from launch and it remains stable until it suddenly shifts by 2 ft + in one circle, then crashes into something the next few. The plane seems unaffected during these shifts. I think I could start with a smaller circle, but the circle always gets wider as the torque decreases. How can I keep the circle constant during the cruise/descent? HS tilt is the obvious solution but it cannot be readily adjusted in competition. Would adding some clay on the inside edge work to lessen the circle by inducing roll? Plane stability could also be increased but because it would involve moving the CG more backward than optimal and lessening the decalage, the plane would fail to make use of the monster 30 ft it has. Preferably the plane should be able to climb to the ceiling and start a slow descent in a tight, unmoving circle. How would I trim for this?
I'm pretty angry because I knew that our plane was better, and we were just one place away from placing. Adding a minute (or maybe even 90 seconds) to our flight time wouldn't have been impossible if our luck had been better (plane wasn't broken the day before, more time to test, and rubber bands cooperating). But this happens, and it wasn't the worst of all outcomes so I'm satisfied. Just a bummer that this was the last invitational and we didn't get the gold.
Flight Log is now privated and sent to the coaches (times nearing 2:30 are too valuable to share the trimming for!!)
Flight Videos:
https://drive.google.com/drive/folders/ ... share_link
(Best flight at the invitational was not recorded but it was basically the first one except it climbed higher and crashed higher, in a different spot)
Note that the 2:26 in the school gym also had a significant circle shift. We got extremely lucky that it did not crash into anything, most flights of that caliber in that venue aren't as lucky.
We also had another flight that was probably even better than the 2:26 - it was a 1:27 that clipped the ceiling of the gym before losing all of its altitude, somehow avoiding all obstacles along the way. This was unrecorded, and yet again circle shift was the culprit of the altitude loss.
Thanks for the advice though. I got the same climb problem but de-winding helps even if it is ridiculously a lot. Only thing with small places is circle drifting (it's mild, not worried about it), but even a little bit and it will crash into walls and stuff.
and I think also trying different rubber and stuff but I just wanted to confirm the trim settings I have now aren’t going to haunt me later